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Journal of Prosthetic Dentistry

Comparative assessment of complete-coverage, fixed tooth-supported prostheses fabricated from digital scans or conventional impressions: A systematic review and meta-analysis

      Abstract

      Statement of problem

      Intraoral scanners have significantly improved over the last decade. Nevertheless, data comparing intraoral digital scans with conventional impressions are sparse.

      Purpose

      The purpose of this systematic review and meta-analysis was to determine the impact of impression technique (digital scans versus conventional impressions) on the clinical time, patient comfort, and marginal fit of tooth-supported prostheses.

      Material and methods

      The authors conducted a literature search based on the Population, Intervention, Comparison, and Outcome (PICO) framework in 3 databases to identify clinical trials with no language or date restrictions. The mean clinical time, patient comfort, and marginal fit values of each study were independently extracted by 2 review authors and categorized according to the scanning or impression method. The authors assessed the study-level risk of bias.

      Results

      A total of 16 clinical studies met the inclusion criteria. The mean clinical time was statistically similar for digital scan procedures (784 ±252 seconds) and for conventional impression methods (1125 ±159 seconds) (P>.05). The digital scan techniques were more comfortable for patients than conventional impressions; the mean visual analog scale score was 67.8 ±21.7 for digital scans and 39.6 ±9.3 for conventional impressions (P<.05). The mean marginal fit was 80.9 ±31.9 μm and 92.1 ±35.4 μm for digital scan and conventional impressions, respectively, with no statistically significant difference (P>.05).

      Conclusions

      Digital scan techniques are comparable with conventional impressions in terms of clinical time and marginal fit but are more comfortable for patients than conventional impression techniques.
      Clinical Implications
      Digital scanning offers significant benefits in terms of patient comfort but remains comparable with conventional impressions in terms of clinical time and marginal fit.
      An accurate dental impression is the first step in the fabrication of indirect restorations.
      • Markovic D.
      • Puskar T.
      • Hadzistevic M.
      • Potran M.
      • Blazic L.
      • Hodolic J.
      The dimensional stability of elastomeric dental impression materials.
      Computer-aided design and computer-aided manufacturing (CAD-CAM) technology has become popular in prosthodontics and is expected to completely digitize the prosthesis fabrication process.
      • Ting-Shu S.
      • Jian S.
      Intraoral digital impression technique: a review.
      As the first step, intraoral scanning should be as accurate as and less time-consuming and more comfortable for patients than conventional impression making.
      Restorations made with CAD-CAM technology have been reported to have marginal accuracy similar to that obtained with the conventional impression technique.
      • Chochlidakis K.M.
      • Papaspyridakos P.
      • Geminiani A.
      • Chen C.J.
      • Feng I.J.
      • Ercoli C.
      Digital versus conventional impressions for fixed prosthodontics: a systematic review and meta-analysis.
      • Tsirogiannis P.
      • Reissmann D.R.
      • Heydecke G.
      Evaluation of the marginal fit of single-unit, complete-coverage ceramic restorations fabricated after digital and conventional impressions: a systematic review and meta-analysis.
      • Joda T.
      • Zarone F.
      • Ferrari M.
      The complete digital workflow in fixed prosthodontics: a systematic review.
      • Ahlholm P.
      • Sipilä K.
      • Vallittu P.
      • Jakonen M.
      • Kotiranta U.
      Digital versus conventional impressions in fixed prosthodontics: a review.
      • Nagarkar S.R.
      • Perdigao J.
      • Seong W.-J.
      • Theis-Mahon N.
      Digital versus conventional impressions for full-coverage restorations: a systematic review and meta-analysis.
      However, digital scanning has been reported to be faster than conventional impression making
      • Patzelt S.B.
      • Lamprinos C.
      • Stampf S.
      • Att W.
      The time efficiency of intraoral scanners: an in vitro comparative study.
      while increasing the effectiveness of the treatment.
      • Polido W.D.
      Digital impressions and handling of digital models: the future of dentistry.
      Patients have been reported to prefer digital scans because they are more comfortable and less time-consuming.
      • Gallardo Y.R.
      • Bohner L.
      • Tortamano P.
      • Pigozzo M.N.
      • Laganá D.C.
      • Sesma N.
      Patient outcomes and procedure working time for digital versus conventional impressions: a systematic review.
      • Burhardt L.
      • Livas C.
      • Kerdijk W.
      • van der Meer W.J.
      • Ren Y.
      Treatment comfort, time perception, and preference for conventional and digital impression techniques: a comparative study in young patients.
      • Burzynski J.A.
      • Firestone A.R.
      • Beck F.M.
      • Fields H.W.
      • Deguchi T.
      Comparison of digital intraoral scanners and alginate impressions: time and patient satisfaction.
      Despite the many advantages of CAD-CAM systems, there are still obstacles and deficiencies to address. Some systems require a layer of powder on the tooth surface, and scanner movement during the scanning process may affect accuracy.
      • Ting-Shu S.
      • Jian S.
      Intraoral digital impression technique: a review.
      Biases at different levels have been identified in previous systematic reviews comparing the 2 recording techniques.
      • Chochlidakis K.M.
      • Papaspyridakos P.
      • Geminiani A.
      • Chen C.J.
      • Feng I.J.
      • Ercoli C.
      Digital versus conventional impressions for fixed prosthodontics: a systematic review and meta-analysis.
      • Tsirogiannis P.
      • Reissmann D.R.
      • Heydecke G.
      Evaluation of the marginal fit of single-unit, complete-coverage ceramic restorations fabricated after digital and conventional impressions: a systematic review and meta-analysis.
      • Joda T.
      • Zarone F.
      • Ferrari M.
      The complete digital workflow in fixed prosthodontics: a systematic review.
      • Ahlholm P.
      • Sipilä K.
      • Vallittu P.
      • Jakonen M.
      • Kotiranta U.
      Digital versus conventional impressions in fixed prosthodontics: a review.
      • Nagarkar S.R.
      • Perdigao J.
      • Seong W.-J.
      • Theis-Mahon N.
      Digital versus conventional impressions for full-coverage restorations: a systematic review and meta-analysis.
      ,
      • Gallardo Y.R.
      • Bohner L.
      • Tortamano P.
      • Pigozzo M.N.
      • Laganá D.C.
      • Sesma N.
      Patient outcomes and procedure working time for digital versus conventional impressions: a systematic review.
      These reviews included both in vivo and in vitro studies, with some being randomized or only descriptive while others concerned implant-supported prostheses. These differences do not allow relevant conclusions to be drawn regarding the differences between the 2 techniques. The purpose of this systematic review and meta-analysis was to compare conventional impression making and digital scanning techniques in terms of clinical time, patient comfort, and the marginal fit of fixed tooth-supported prostheses. The null hypothesis was that conventional impression making and digital scanning techniques would result in restorations of fixed tooth-supported prostheses with similar clinical time, patient comfort, and marginal fit.

      Material and methods

      The protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO) (http://www.crd.york.ac.uk/PROSPERO) under the number CRD42019137141. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.
      • Liberati A.
      • Altman D.G.
      • Tetzlaff J.
      • Mulrow C.
      • Gøtzsche P.C.
      • Ioannidis J.P.A.
      • et al.
      The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration.
      The Population, Intervention, Comparison, and Outcome (PICO) framework was used to formulate the following 3 questions: Are digital scans made with intraoral scan systems less time-consuming than conventional impressions (PICO 1)? Do digital scan techniques cause significantly less discomfort to patients than conventional impression techniques (PICO 2)? Are digital scans more accurate than conventional impression methods in terms of marginal fit (PICO 3)?
      The Medline/PubMed, Cochrane Library, and Science Direct databases were used to carry out an electronic search for articles published through 2020 with no date and language restrictions. Within the databases, the following keyword combinations (medical subject headings [MeSH] and free-text terms) were used: “clinical efficiency”/“patient comfort”/“patient preference”/“digital workflow”/“conventional workflow”/“systematic review”/“meta-analysis”/“internal fit”/“marginal fit”/“randomized controlled trials”/“fixed dental prosthesis”/“prospective study”/“comparative study”/“time work” AND/OR “conventional impression”/“dental impression techniques”/“digital scans”/“computer-aided design”/“computer-aided manufacturing”/“intraoral scanner” to identify prospective or randomized controlled clinical studies concerning fixed tooth-supported prostheses and those in which the authors compared conventional impression techniques with digital scans. The articles were selected based on the following inclusion criteria: controlled and randomized clinical trials, as well as prospective comparative studies; comparison between conventional and digital scan techniques for complete-coverage, fixed, tooth-supported prosthetic rehabilitations; and studies evaluating clinical time, patient comfort, and marginal fit.
      Meta-analyses or literature reviews, in vitro studies or those without available data, fixed prosthetic rehabilitations that were not tooth-supported, noncontrolled clinical studies, clinical case reports or duplicate publications on the same subject with the same participants, studies that did not compare conventional and digital scan techniques, clinical case series, and studies with fewer than 10 participants were excluded.
      Bibliographic research was performed by one of the authors (O.N.B.). All references found in the 3 databases were imported into a reference management software program (Zotero; Corporation for Digital Scholarship) for article management, including removal of duplicate articles. In the software program, 2 reviewers (P.L.B., O.N.B.) analyzed the studies independently in 3 phases by searching the titles, analyzing the abstracts, and identifying full-text articles. Supplemental manual searches were performed on all the eligible articles to enlarge the list of retained articles. Disagreements were resolved through discussion. An identifier was assigned to each included study.
      Data extraction and synthesis were performed independently by the authors (P.L.B., O.N.B.) with a spreadsheet (Excel 2010; Microsoft Corp). Missing data or additional study information were requested by contacting the studies’ corresponding authors. If additional data were not received after 3 contact attempts, the study was excluded from the quantitative aspect and included in the qualitative aspect of the review. The author and year of publication, country, sample size, study design, study group, type of material covering the crown, variables evaluated, evaluation method, and main results were extracted.
      Bias risks were evaluated for all included studies by the 3 authors of the review (P.L.B., O.N.B., A.G.) in accordance with the criteria proposed in the Cochrane Handbook regarding randomized controlled studies. This evaluation concerned the generation of the randomization sequence (selection bias), concealment of the allocation (reporting bias), blinding of the investigator and the participant (confusion bias), blind evaluation of the results (performance bias), management of missing data (attrition bias), selection of the reporter, and other types of bias. From these criteria, the bias risk level was determined to be low, unclear, or high.
      A qualitative synthesis of the findings from the included studies, structured around different outcomes, was conducted. The intervention effects for each study were summarized by calculating the mean differences for continuous outcomes or risk ratios (for dichotomous outcomes). However, when studies used the same type of intervention and comparison groups with the same outcome measure, the results were pooled by using a random-effects model (DerSimonian and Laird method),
      • DerSimonian R.
      • Laird N.
      Meta-analysis in clinical trials.
      with mean differences for continuous outcomes and risk ratios for dichotomous outcomes and calculated 95% confidence intervals and P values for each outcome. Heterogeneity between the studies was assessed by using the Higgins I2 statistic.
      • Higgins J.P.T.
      • Thompson S.G.
      Quantifying heterogeneity in a meta-analysis.
      An I2 value of 50% or more was considered the presence of substantial heterogeneity. A sensitivity analysis based on the risk of bias of the included studies (low risk of bias versus high or unclear risk of bias) was conducted. A stratified (subgroup) meta-analyses was used to explore heterogeneity in effect estimates according to the study design. Evidence of publication bias was also assessed by using the extended trim-and-fill method. When the study authors had used several scanners, the scanner with the greatest error was used for data pooling.

      Results

      Electronic searches, complemented by manual searches, identified 4959 articles, of which 52 were duplicates and 4868 were excluded after reading the titles and/or the summaries. The texts of the 39 eligible articles were read in their entirety to select those that corresponded to the inclusion and exclusion criteria. According to these criteria, 23 articles were excluded,
      • Chochlidakis K.M.
      • Papaspyridakos P.
      • Geminiani A.
      • Chen C.J.
      • Feng I.J.
      • Ercoli C.
      Digital versus conventional impressions for fixed prosthodontics: a systematic review and meta-analysis.
      • Tsirogiannis P.
      • Reissmann D.R.
      • Heydecke G.
      Evaluation of the marginal fit of single-unit, complete-coverage ceramic restorations fabricated after digital and conventional impressions: a systematic review and meta-analysis.
      • Joda T.
      • Zarone F.
      • Ferrari M.
      The complete digital workflow in fixed prosthodontics: a systematic review.
      • Ahlholm P.
      • Sipilä K.
      • Vallittu P.
      • Jakonen M.
      • Kotiranta U.
      Digital versus conventional impressions in fixed prosthodontics: a review.
      • Nagarkar S.R.
      • Perdigao J.
      • Seong W.-J.
      • Theis-Mahon N.
      Digital versus conventional impressions for full-coverage restorations: a systematic review and meta-analysis.
      ,
      • Gallardo Y.R.
      • Bohner L.
      • Tortamano P.
      • Pigozzo M.N.
      • Laganá D.C.
      • Sesma N.
      Patient outcomes and procedure working time for digital versus conventional impressions: a systematic review.
      • Burhardt L.
      • Livas C.
      • Kerdijk W.
      • van der Meer W.J.
      • Ren Y.
      Treatment comfort, time perception, and preference for conventional and digital impression techniques: a comparative study in young patients.
      • Burzynski J.A.
      • Firestone A.R.
      • Beck F.M.
      • Fields H.W.
      • Deguchi T.
      Comparison of digital intraoral scanners and alginate impressions: time and patient satisfaction.
      ,
      • Grünheid T.
      • McCarthy S.D.
      • Larson B.E.
      Clinical use of a direct chairside oral scanner: an assessment of accuracy, time, and patient acceptance.
      • Flügge T.V.
      • Schlager S.
      • Nelson K.
      • Nahles S.
      • Metzger M.C.
      Precision of intraoral digital dental impressions with iTero and extraoral digitization with the iTero and a model scanner.
      • Schaefer O.
      • Decker M.
      • Wittstock F.
      • Kuepper H.
      • Guentsch A.
      Impact of digital impression techniques on the adaption of ceramic partial crowns in vitro.
      • Almeida e Silva J.S.
      • Erdelt K.
      • Edelhoff D.
      • Araújo É.
      • Stimmelmayr M.
      • Vieira L.C.
      • et al.
      Marginal and internal fit of four-unit zirconia fixed dental prostheses based on digital and conventional impression techniques.
      • Alfaro D.P.
      • Ruse N.D.
      • Carvalho R.M.
      • Wyatt C.C.
      Assessment of the internal fit of lithium disilicate crowns using micro-CT.
      • Solaberrieta E.
      • Otegi J.R.
      • Goicoechea N.
      • Brizuela A.
      • Pradies G.
      Comparison of a conventional and virtual occlusal record.
      • Afify A.
      • Haney S.
      • Verrett R.
      • Mansueto M.
      • Cray J.
      • Johnson R.
      Marginal discrepancy of noble metal-ceramic fixed dental prosthesis frameworks fabricated by conventional and digital technologies.
      • Cave V.
      • Keys W.
      Digital and conventional impressions have similar working times.
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      • Mühlemann S.
      • Benic G.I.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Sailer I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic posterior fixed partial dentures. Part II: time efficiency of CAD-CAM versus conventional laboratory procedures.
      • Sailer I.
      • Benic G.I.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Mühlemann S.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part II: CAD-CAM versus conventional laboratory procedures.
      • Batisse C.
      • Bessadet M.
      • Decerle N.
      • Veyrune J.L.
      • Nicolas E.
      Ceramo-metal crown or CAD-CAM rehabilitation: patient and practitioner appraisal.
      • Berrendero S.
      • Salido M.P.
      • Ferreiroa A.
      • Valverde A.
      • Pradíes G.
      Comparative study of all-ceramic crowns obtained from conventional and digital impressions: clinical findings.
      • Al Hamad K.Q.
      • Al Rashdan B.A.
      • Al Omari W.M.
      • Baba N.Z.
      Comparison of the fit of lithium disilicate crowns made from conventional, digital, or conventional/digital techniques.
      and the reasons for their exclusion are presented in Table 1. Ultimately, only 14 randomized controlled crossover studies or parallel groups and 2 prospective comparative studies were included.
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      ,
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      ,
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Accuracy of crowns based on digital intraoral scanning compared to conventional impression—a split-mouth randomised clinical study.
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      • Zeltner M.
      • Sailer I.
      • Mühlemann S.
      • Özcan M.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit.
      • Rödiger M.
      • Heinitz A.
      • Bürgers R.
      • Rinke S.
      Fitting accuracy of zirconia single crowns produced via digital and conventional impressions-a clinical comparative study.
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      • Boeddinghaus M.
      • Breloer E.S.
      • Rehmann P.
      • Wöstmann B.
      Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients.
      • Zarauz C.
      • Valverde A.
      • Martinez-Rus F.
      • Hassan B.
      • Pradies G.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions.
      • Pradíes G.
      • Zarauz C.
      • Valverde A.
      • Ferreiroa A.
      • Martínez-Rus F.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      • Syrek A.
      • Reich G.
      • Ranftl D.
      • Klein C.
      • Cerny B.
      • Brodesser J.
      Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling.
      The bibliographic research flow chart is presented in Figure 1, and the characteristics of the included studies, the main parameters, and the results of the 16 articles are shown in Table 2.
      Table 1Characteristics of excluded studies
      StudyReason for Exclusion
      Chochlidakis et al,
      • Chochlidakis K.M.
      • Papaspyridakos P.
      • Geminiani A.
      • Chen C.J.
      • Feng I.J.
      • Ercoli C.
      Digital versus conventional impressions for fixed prosthodontics: a systematic review and meta-analysis.
      Tsirogiannis et al,
      • Tsirogiannis P.
      • Reissmann D.R.
      • Heydecke G.
      Evaluation of the marginal fit of single-unit, complete-coverage ceramic restorations fabricated after digital and conventional impressions: a systematic review and meta-analysis.
      Nagarkar et al
      • Nagarkar S.R.
      • Perdigao J.
      • Seong W.-J.
      • Theis-Mahon N.
      Digital versus conventional impressions for full-coverage restorations: a systematic review and meta-analysis.
      Systematic review and meta-analysis
      Joda et al,
      • Joda T.
      • Zarone F.
      • Ferrari M.
      The complete digital workflow in fixed prosthodontics: a systematic review.
      Ahlholm et al,
      • Ahlholm P.
      • Sipilä K.
      • Vallittu P.
      • Jakonen M.
      • Kotiranta U.
      Digital versus conventional impressions in fixed prosthodontics: a review.
      Gallardo et al,
      • Gallardo Y.R.
      • Bohner L.
      • Tortamano P.
      • Pigozzo M.N.
      • Laganá D.C.
      • Sesma N.
      Patient outcomes and procedure working time for digital versus conventional impressions: a systematic review.
      Cave and Keys
      • Cave V.
      • Keys W.
      Digital and conventional impressions have similar working times.
      Systematic review
      Burhardt et al,
      • Burhardt L.
      • Livas C.
      • Kerdijk W.
      • van der Meer W.J.
      • Ren Y.
      Treatment comfort, time perception, and preference for conventional and digital impression techniques: a comparative study in young patients.
      Burzynski et al,
      • Burzynski J.A.
      • Firestone A.R.
      • Beck F.M.
      • Fields H.W.
      • Deguchi T.
      Comparison of digital intraoral scanners and alginate impressions: time and patient satisfaction.
      Grünheid et al
      • Grünheid T.
      • McCarthy S.D.
      • Larson B.E.
      Clinical use of a direct chairside oral scanner: an assessment of accuracy, time, and patient acceptance.
      Orthodontic patients
      Flügge et al
      • Flügge T.V.
      • Schlager S.
      • Nelson K.
      • Nahles S.
      • Metzger M.C.
      Precision of intraoral digital dental impressions with iTero and extraoral digitization with the iTero and a model scanner.
      Not prosthodontic treatment
      Schaefer et al,
      • Schaefer O.
      • Decker M.
      • Wittstock F.
      • Kuepper H.
      • Guentsch A.
      Impact of digital impression techniques on the adaption of ceramic partial crowns in vitro.
      Almeida e Silva et al,
      • Almeida e Silva J.S.
      • Erdelt K.
      • Edelhoff D.
      • Araújo É.
      • Stimmelmayr M.
      • Vieira L.C.
      • et al.
      Marginal and internal fit of four-unit zirconia fixed dental prostheses based on digital and conventional impression techniques.
      Alfaro et al,
      • Alfaro D.P.
      • Ruse N.D.
      • Carvalho R.M.
      • Wyatt C.C.
      Assessment of the internal fit of lithium disilicate crowns using micro-CT.
      Solaberrieta et al,
      • Solaberrieta E.
      • Otegi J.R.
      • Goicoechea N.
      • Brizuela A.
      • Pradies G.
      Comparison of a conventional and virtual occlusal record.
      Afify et al
      • Afify A.
      • Haney S.
      • Verrett R.
      • Mansueto M.
      • Cray J.
      • Johnson R.
      Marginal discrepancy of noble metal-ceramic fixed dental prosthesis frameworks fabricated by conventional and digital technologies.
      In vitro study
      Sailer et al,
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      Benic et al
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      Double publication by same authors
      Mühlemann et al,
      • Mühlemann S.
      • Benic G.I.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Sailer I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic posterior fixed partial dentures. Part II: time efficiency of CAD-CAM versus conventional laboratory procedures.
      Sailer et al
      • Sailer I.
      • Benic G.I.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Mühlemann S.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part II: CAD-CAM versus conventional laboratory procedures.
      Laboratory procedures
      Batisse et al,
      • Batisse C.
      • Bessadet M.
      • Decerle N.
      • Veyrune J.L.
      • Nicolas E.
      Ceramo-metal crown or CAD-CAM rehabilitation: patient and practitioner appraisal.
      Berrendero et al
      • Berrendero S.
      • Salido M.P.
      • Ferreiroa A.
      • Valverde A.
      • Pradíes G.
      Comparative study of all-ceramic crowns obtained from conventional and digital impressions: clinical findings.
      No data available
      Al Hamad et al
      • Al Hamad K.Q.
      • Al Rashdan B.A.
      • Al Omari W.M.
      • Baba N.Z.
      Comparison of the fit of lithium disilicate crowns made from conventional, digital, or conventional/digital techniques.
      One patient
      Table 2Characteristics of included studies and main results
      IDStudy ReferenceStudy DesignStudy GroupSample Size Restoration MaterialParameters EvaluatedEvaluation MethodMain Results
      1
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      Koulivand et al, 2019, IranPCS, crossover

      2-armed design
      CG (n=15): one-step impression technique (PVS)+casts+EOS

      GT (n=15): TRIOS
      30 MCCMarginal gap (PICO3)

      Clinical time (CT) (PICO1)
      Marginal fit measured with RT under stereomicroscope at ×50 magnification

      CT steps for CI and DS: selection tray, adhesive/uploading patient information, putty preparation, maxillary/madibular impression/scan, placement cord, occlusion record, cord removal and writing laboratory prescription
      Marginal gap in digital technique (GT) significantly lower than values in CI (CG) and digital technique superior in terms of impression time.
      2
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Accuracy of crowns based on digital intraoral scanning compared to conventional impression—a split-mouth randomised clinical study.
      Haddadi et al, 2019, DenmarkRCT, crossover

      2-armed design
      CG (n=19): one-step impression technique (PVS)+stone casts+EOS

      GT (n=19): TRIOS
      38 LDCsMarginal gap (PICO3)Marginal fit evaluated with RT using Macroscope M420 at ×40 magnification on computer screen.Comparing to CI (CG), crowns based on IOS (GT) significantly better marginal adaptation at all points except at cusp tip.
      3
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      Haddadi et al, 2018, DenmarkRCT, crossover

      2-armed design
      CG (n=19): one-step impression technique (PVS)

      GT (n=19): TRIOS
      38 LDCsClinical time (PICO1)

      Patient comfort (PICO2)
      Steps of CI and DS CT: tray selection and adhesive, maxillary/mandibular impression/scan, interocclusal record, shade selection

      Patient perception associated with each method recorded using visual analog scale (VAS) scored 0-100, with 100 indicating maximum discomfort.
      DS (GT) less time consuming and caused significantly less discomfort to patients than CI (CG) made with PVS in complete-arch tray.
      4
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      Sailer et al, 2018, SwitzerlandRCT, crossover

      4-armed design
      CG (n=10): polyether impression

      GT I (n=10): Lava C.O.S

      GT II (n=10): iTero

      GT III (n=10): Bluecam
      NAClinical time (PICO1)

      Patient comfort (PICO2)
      CT's steps: powdering, impressions, occlusal registration and number of impression remakes.

      Participant perceptions of comfort of both impressions rated by means of VAS scored 0 “very uncomfortable” to 100 “comfortable.”
      CI (CG) procedures objectively less time consuming and subjectively preferred by participants over digital scan procedures (GT I, II, II).

      System without need for powdering preferred to systems with powdering.
      5
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      Benic et al, 2018, SwitzerlandRCT, crossover

      4-armed design
      CG (n=10): polyether impression+ stone casts+LWT

      GT I (n=10): Lava C.O.S

      GT II (n=10): iTero

      GT III (n=10): Bluecam
      30 PFZFPDs

      10 MFPDs
      Marginal fit (PICO3)Marginal discrepancy evaluated in 4 different regions of interest with RT using light microscope at ×200 magnification with replica technique.Digitally (GT I, II, III) fabricated zirconia frameworks for 3-unit fixed dental prostheses have similar or better marginal fit than that of conventionally fabricated metal frameworks (CG).
      6
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      Sakornwimon and Leevailoj, 2017, ThailandRCT 2- parallel groupsCG (n=8): One-step/double–mix impression technique (PVS)+casts+EOS

      GT (n=8): Lava C.O.S
      16 MZCsMarginal fit (PICO3)

      Patient comfort (PICO2)
      Marginal fit assessed by RT using stereomicroscope at ×40 magnification.

      VAS scores ranging from 0 “not satisfactory” to 10 “very satisfactory” used to assess patient comfort.
      VAS scores for DS (GT) significantly higher than those for PVS impressions (CG) in every topic, except for occlusal registration. No differences found in clinical marginal fit of zirconia crowns fabricated from either DS compared with PVS impressions.
      7
      • Zeltner M.
      • Sailer I.
      • Mühlemann S.
      • Özcan M.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit.
      Zeltner et al, 2017, SwitzerlandRCT, crossover

      5-armed design
      CG (n=10): PVS impressions+stone casts+LWT

      GT I (n=10): Lava C.O.S

      GT II (n=10): iTero

      GT III (n=10): Bluecam

      GT IV (n=10): Bluecam
      50 MLDCsMarginal discrepancy (PICO3)Dimensions of marginal discrepancy assessed RT using light microscopy at ×200 magnification.LDCs fabricated with digital workflows (GT I, II, III, IV) similar marginal fit to that of conventionally (CG) fabricated LDCs.

      Differences between treatment modalities not statistically significant (P>.05).
      8
      • Rödiger M.
      • Heinitz A.
      • Bürgers R.
      • Rinke S.
      Fitting accuracy of zirconia single crowns produced via digital and conventional impressions-a clinical comparative study.
      Rödiger et al, 2017, GermanyPCS, crossover

      2-armed design
      CG (n=20): one-step impression technique (PVS)+stone models+EOS

      GT (n=20): TRIOS
      20 ZCsMarginal fit (PICO3)Marginal fit measured with RT on digital photographs captured by integrated camera of light microscope with magnification factor of ×35 and special measuring software program (Axio Vision LE 4.8; Carl Zeiss Microscopy GmbH).Zirconia single crowns produced with both digital (GT) and traditional (CG) impression techniques showed no significant differences in terms of marginal fit between 2 groups.
      9
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      Gjelvold et al, 2016, SwedenRCT 2-parallel groupsCG (n=24): one-step impression technique (polyether) GT (n=24): TRIOS13 LDCs

      16 ZCs

      19 MCCs
      Marginal fit (PICO3)

      Clinical time (PICO1)

      Patient comfort (PICO2)
      Marginal fit evaluated using explorers with defined tip diameters of 150 μm DS and CI CT's steps: cord placement, choice tray, entry patient data, laboratory requisition, impression time, interocclusal registration.

      Patients conveyed their assessments on nonnumerical 100-mm line ranging from 0 “not uncomfortable” at all to 100 “very uncomfortable.”
      Digital scanning technique (GT) less time consuming and more convenient for patients.
      10
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      Berrendero et al, 2016, SpainRCT, crossover

      2-armed design
      CG (n=30):2-step impression technique (PVS)+master cast+EOS

      GT (n=30): TRIOS
      60 PFZCsMarginal fit (PICO3)Marginal fit measured with RT at different areas using stereomicroscopy at ×40 magnification.Ceramic crowns fabricated using IOS (GT) comparable to elastomer conventional impressions (CG) in terms of marginal fit. Mean marginal fit in both groups within limits of clinical acceptability.
      11
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      Ahrberg et al, 2016, GermanyRCT, crossover

      2-armed design
      CG (n=25): monophase impression technique (polyether)+stone models+EOS

      GT (n=25): Lava C.O.S
      34 PFZCs

      16 PFZFPDs
      Marginal fit (PICO3)

      Clinical time (PICO1)
      Marginal fit recorded using RT under light microscope at ×64 magnification

      DS and CI CT's steps: powdering/stock tray individualization; maxillary/mandibular impressions or scan and occlusal registration
      Significantly better marginal fit noted with direct digitalization (GT). Intraoral digital scans also less time consuming for patient than CI (CG).
      12
      • Boeddinghaus M.
      • Breloer E.S.
      • Rehmann P.
      • Wöstmann B.
      Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients.
      Boeddinghaus et al, 2015, GermanyRCT, crossover

      4-armed design
      CG (n=24): 2-step impression technique (polyether)+master model+EOS

      GT I (n=24): Omnicam

      GT II (n=24): Lava Tdef

      GT III (n=24): TRIOS
      49 PFZCsMarginal fit (PICO3)Marginal fit evaluated with RT using microscope with ×40 magnification, built-in CCD camera (M420; Leica) and digital measuring devices attached (Digimatic Micrometer Head; Mitutoyo).Digital scan (GT I, II, III) can be alternative to conventional impression (CG) with consecutive digital workflow when finish line clearly visible and possible to keep it dry.
      13
      • Zarauz C.
      • Valverde A.
      • Martinez-Rus F.
      • Hassan B.
      • Pradies G.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions.
      Zarauz et al, 2015, SpainRCT, crossover

      2-armed design
      CG (n=20): one-step impression (PVS)+master models+EOS

      GT (n=20): iTero
      52 PFZCsMarginal gap (PICO3)Marginal misfit measured with RT in micrometers using stereomicroscopy with magnification of ×40.Ceramic crowns fabricated from intraoral digital scans (GT) demonstrated significantly better marginal fit than crowns from traditional impressions (CG).
      14
      • Pradíes G.
      • Zarauz C.
      • Valverde A.
      • Ferreiroa A.
      • Martínez-Rus F.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.
      Pradíes et al, 2014, SpainRCT, crossover

      2-armed design
      CG (n=32): 2-step impression technique (PVS)+master cast+EOS

      GT (n=32): Lava C.O.S.
      60 PFZCsMarginal fit (PICO3)Marginal fit evaluated with RT by means of stereomicroscope (M-80; Leica) at magnification factor ×40, with built-in charge-coupled camera (Hitachi CCTV HV-720E; Hitachi).Digital scans obtained from Lava C.O.S can be used for manufacturing ceramic crowns in normal clinical practice with better marginal fit than conventional impressions with elastomers.
      15
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      Yuzbasioglu et al, 2014, TurkeyRCT, crossover

      2-armed design
      CG (n=24): monophase impression technique (polyether)

      GT I (n=24): Omnicam
      48 PFZCsClinical time (PICO1)

      Patient comfort (PICO2)
      CI and DS CT steps: tray selection and adhesive/intering patient information, laboratory prescription, maxillary/mandibular impression/scan, occlusal registration.

      VAS scored 0 “uncomfortable” to 100 “very comfortable” used to assess patient preferences and self-concerns.
      Digital scans (GT) resulted in more time-efficient technique than conventional impressions (CG).

      Patients stated that digital scans more comfortable than conventional techniques.
      16
      • Syrek A.
      • Reich G.
      • Ranftl D.
      • Klein C.
      • Cerny B.
      • Brodesser J.
      Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling.
      Syrek et al, 2010, GermanyRCT, crossover

      2-armed design
      CG (n=20): 2-step impression technique (PVS)+master model+EOS

      GT (n=20): Lava C.O.S.
      Marginal fit (PICO3)Marginal fit measured with RT by means of stereomicroscope (Stemi SVII; Zeiss) at ×66 magnification at buccal, lingual, mesial, and distal margin.Crowns from IOS (GT) revealed significantly better marginal fit than crowns from silicone impressions (CG). Marginal discrepancies in both groups were within limits of clinical acceptability.
      CG, control group; CI, conventional impression; CT, clinical time; DS, digital scan; EOS, extraoral scanner; GT, group test; IOS, intraoral scanner; LDCs, lithium disilicate ceramic crowns; LWT, lost-wax technique; MCC, metallo-ceramic crowns; MFPD, metal fixed partial denture; MLDCs, monolithic lithium disilicate ceramic crowns; MZC, monolithic zirconia crowns; NA, not applicable; PCS, prospective comparative study; PFZFPD, porcelain fused to zirconia fixed partial denture; PVS, polyvinyl siloxane; RCT, randomized controlled clinical trial; RT, replica technique; VAS, visual analog scale; ZC, zirconia single crown.
      Lava Chairside Oral Scanner (C.O.S); TRIOS (3Shape A/S); iTero (Align Technology); CEREC Bluecam (Dentsply Sirona); Cerec Omnicam (Dentsply Sirona).
      The details of the answers to the 3 questions asked are summarized as follows:
      The PICO 1 question (clinical time) was studied in 6 investigations by using a stopwatch to measure this parameter.
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      ,
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      ,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      ,
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      ,
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      ,
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      Data pooling showed no statistically significant difference between the 2 techniques (digital scans: 784 ±252 seconds; conventional impressions: 1125 ±159 seconds) (P>.05) (Table 3). The PICO 2 question (patient comfort) was evaluated in 5 studies by using a visual analog scale (VAS) to assess the comfort level or preferences of participants during the procedure.
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      ,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      ,
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      ,
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      ,
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      A harmonization of this scale from “0=uncomfortable” to “100=very comfortable” was carried out to facilitate the synthesis of the data. The mean VAS score was lower in participants who received conventional impressions (39.6 ±9.3) rather than digital scans (67.8 ±21.7), and the difference was statistically significant (P<.05) (Table 4). These results show that patients preferred intraoral scanning over conventional impression methods.
      Table 3Mean time recording for scanning with digital system scans and conventional impression material
      Study ReferenceNo. Procedures Evaluated/-GroupIntraoral ScannersDS secCI∗ secMD sec, 95% CIP
      MeanSDMeanSD
      1
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      25TRIOS631NR1167NR-536<.05
      3
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      19TRIOS311NR1119NR-808<.05
      4
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      10Lava C.O.S1091523658181433<.05
      9
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      24TRIOS8733271242342-369<.05
      11
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      25Lava C.O.S1548NR1960NR-412<.05
      15
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      24Omnicam2492360524-356<.05
      Total mean time (sec)7842521125159-341 (CI, -974; 291)>.05
      CI∗, conventional impressions; CI, confidence interval; DS, digital scans; MD, mean difference; No., number; NR, not reported; SD, standard deviation; sec, seconds.
      Lava Chairside Oral Scanner (C.O.S); TRIOS (3Shape A/S); Cerec Omnicam (Dentsply Sirona); significant at P<.05.
      Table 4Visual analog scale average characterizing patient comfort during digital scanning and conventional impressions
      Study ReferenceNo. PatientsIntraoral ScannersDSCI∗MD, 95% CIP
      MeanSDMeanSD
      3
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      19TRIOS62NR8.4NR53.6<.05
      4
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      10iTero73177424-1>.05
      6
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      16Lava C.O.S80.310.960.810.419.5<.05
      9
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      48TRIOS6558.726.72.738.3<.05
      15
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      24Omnicam5937.728.118.430.96<.05
      Total67.821.739.69.328.2 (CI, -1.1; 57.5)<.05
      CI∗, conventional impressions; CI, confidence interval; DS, digital scans; MD, mean difference; NR, not reported; No., number of; SD, standard deviation.
      TRIOS (3Shape A/S); iTero (Align Technology); Lava Chairside Oral Scanner (COS); Cerec Omnicam (Dentsply Sirona); significant at P<.05.
      The PICO 3 question (marginal fit) was evaluated in 13 articles that measured the perpendicular distance from the internal surface at the margin of the restoration to the preparation finish line through the silicone replica technique or a 150-μm-diameter explorer.
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      ,
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      ,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Accuracy of crowns based on digital intraoral scanning compared to conventional impression—a split-mouth randomised clinical study.
      ,
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      • Zeltner M.
      • Sailer I.
      • Mühlemann S.
      • Özcan M.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit.
      • Rödiger M.
      • Heinitz A.
      • Bürgers R.
      • Rinke S.
      Fitting accuracy of zirconia single crowns produced via digital and conventional impressions-a clinical comparative study.
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      • Boeddinghaus M.
      • Breloer E.S.
      • Rehmann P.
      • Wöstmann B.
      Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients.
      • Zarauz C.
      • Valverde A.
      • Martinez-Rus F.
      • Hassan B.
      • Pradies G.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions.
      • Pradíes G.
      • Zarauz C.
      • Valverde A.
      • Ferreiroa A.
      • Martínez-Rus F.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.
      ,
      • Syrek A.
      • Reich G.
      • Ranftl D.
      • Klein C.
      • Cerny B.
      • Brodesser J.
      Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling.
      To observe the gaps between the prosthesis and the tooth margin, 5 studies used a light microscope,
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      ,
      • Zeltner M.
      • Sailer I.
      • Mühlemann S.
      • Özcan M.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit.
      ,
      • Rödiger M.
      • Heinitz A.
      • Bürgers R.
      • Rinke S.
      Fitting accuracy of zirconia single crowns produced via digital and conventional impressions-a clinical comparative study.
      ,
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      ,
      • Boeddinghaus M.
      • Breloer E.S.
      • Rehmann P.
      • Wöstmann B.
      Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients.
      7 used a stereomicroscope,
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      ,
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      ,
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      ,
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      ,
      • Zarauz C.
      • Valverde A.
      • Martinez-Rus F.
      • Hassan B.
      • Pradies G.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions.
      ,
      • Pradíes G.
      • Zarauz C.
      • Valverde A.
      • Ferreiroa A.
      • Martínez-Rus F.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.
      ,
      • Syrek A.
      • Reich G.
      • Ranftl D.
      • Klein C.
      • Cerny B.
      • Brodesser J.
      Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling.
      1 used a macroscope,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Accuracy of crowns based on digital intraoral scanning compared to conventional impression—a split-mouth randomised clinical study.
      and 1 used an explorer.
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      The average marginal fit values were lower for digital scanning techniques (80.9 ±31.9 μm) than for conventional impressions (92.1 ±35.4 μm), but the difference was not statistically significant (P>.05) (Table 5). These results were clinically acceptable, as the values were below the 100 μm typically cited.
      • Nagarkar S.R.
      • Perdigao J.
      • Seong W.-J.
      • Theis-Mahon N.
      Digital versus conventional impressions for full-coverage restorations: a systematic review and meta-analysis.
      The studies were heterogeneous, so a meta-analysis on this endpoint would have had little relevance.
      Table 5Data on measurements of marginal fit between conventional impression and digital scanning techniques
      Study ReferenceNo. Protheses EvaluatedIntraoral ScannersDS μmCI∗ μmMD μm, 95% CIP
      MeanSDMeanSD
      1
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      30TRIOS60.1NR97NR-36.9<.05
      2
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Accuracy of crowns based on digital intraoral scanning compared to conventional impression—a split-mouth randomised clinical study.
      38TRIOS72NR83NR-11<.05
      5
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      10infiniDent108.393.8117.7129.4-9.4>.05
      6
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      16Lava C.O.S61.55.8156.335.2>.05
      7
      • Zeltner M.
      • Sailer I.
      • Mühlemann S.
      • Özcan M.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit.
      10iTero127.858.390.466.137.4>.05
      8
      • Rödiger M.
      • Heinitz A.
      • Bürgers R.
      • Rinke S.
      Fitting accuracy of zirconia single crowns produced via digital and conventional impressions-a clinical comparative study.
      20TRIOS87.491.282.275.25.2>.05
      10
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      30TRIOS106.669.6119.960-13.3>.05
      11
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      33Lava C.O.S61.124.870.428.7-9.3<.05
      13
      • Zarauz C.
      • Valverde A.
      • Martinez-Rus F.
      • Hassan B.
      • Pradies G.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions.
      26iTero80.326.2133.548.8-53.2<.05
      14
      • Pradíes G.
      • Zarauz C.
      • Valverde A.
      • Ferreiroa A.
      • Martínez-Rus F.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.
      34Lava C.O.S76.365.391.572.2-15.1<.05
      16
      • Syrek A.
      • Reich G.
      • Ranftl D.
      • Klein C.
      • Cerny B.
      • Brodesser J.
      Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling.
      20Lava C.O.S49247139-22<.05
      Total26780.931.992.135.4-11.1 [CI, -32.5; 10.4]>.05
      μm, micrometers; CI∗, conventional impressions; CI, confidence interval; DS, digital scans; MD, mean difference; NR, not reported; No., number; SD, standard deviation.
      TRIOS (3Shape A/S); Cerec infiniDent (Dentsply Sirona); Lava Chairside Oral Scanner (COS); iTero (Align Technology); significant at P<.05.
      Only 2 studies compared the conventional impression and digital scan techniques regarding practitioner difficulties,
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      ,
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      and 9 analyzed the internal fit of the prostheses by measuring the distance between the die and the intaglio surface of the crown.
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      ,
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      ,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Accuracy of crowns based on digital intraoral scanning compared to conventional impression—a split-mouth randomised clinical study.
      ,
      • Zeltner M.
      • Sailer I.
      • Mühlemann S.
      • Özcan M.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit.
      ,
      • Rödiger M.
      • Heinitz A.
      • Bürgers R.
      • Rinke S.
      Fitting accuracy of zirconia single crowns produced via digital and conventional impressions-a clinical comparative study.
      ,
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      ,
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      ,
      • Zarauz C.
      • Valverde A.
      • Martinez-Rus F.
      • Hassan B.
      • Pradies G.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions.
      ,
      • Pradíes G.
      • Zarauz C.
      • Valverde A.
      • Ferreiroa A.
      • Martínez-Rus F.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.
      For practitioner difficulties, the authors’ findings were contradictory, and the 2 techniques were comparable in terms of internal fit values.
      Among the studies included in this review, 9 presented an elevated risk of bias because of the absence of blinded investigators and participant or result evaluation. However, 7 studies showed an unclear to low risk of bias (Fig. 2). The overall quality of evidence was low in all studies.
      Figure thumbnail gr2
      Figure 2Risk of bias of included studies. Yellow indicates low risk of bias, gray indicates unclear risk of bias, and blue indicates high risk of bias.

      Discussion

      This systematic review included 16 clinical studies that compared digital scanning and conventional impression techniques in terms of clinical time, patient comfort, and marginal fit.
      The null hypothesis was rejected for patient comfort but not for clinical time or marginal fit.
      For the clinical time, the findings were divergent. Sailer et al
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      reported that conventional impression procedures were objectively less time-consuming than digital scanning procedures (P<.05). Nevertheless, other authors
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      ,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      ,
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      ,
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      ,
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      reported that the digital scan was a more time-efficient technique than conventional impressions (P<.05). The steps used to evaluate this parameter differed among studies, which explains the variability in the results. In addition, the learning curve and practitioner experience seemed to play a decisive role in impression-making duration. However, Haddadi et al
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      suggested that the operator has the option to “repair” a scan if a certain area is assessed as substandard. With the conventional technique, a defect is discovered only after complete polymerization of the impression material. If a defect is present, the only option is to remake the impression. It would seem wise to standardize the steps of the clinical time to draw pertinent conclusions in favor of one technique or the other.
      Patient comfort was evaluated in 5 studies,
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      ,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Evaluation of operating time and patient perception using conventional impression taking and intraoral scanning for crown manufacture: a split-mouth, randomized clinical study.
      ,
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      ,
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      ,
      • Yuzbasioglu E.
      • Kurt H.
      • Turunc R.
      • Bilir H.
      Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes.
      and pooled data showed that the digital scan technique was more comfortable than conventional impression making (P<.05). However, one factor reducing the comfort for the patients was the need to powder the intraoral environment for some of the digital scanners.
      • Sailer I.
      • Mühlemann S.
      • Fehmer V.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: time efficiency of complete-arch digital scans versus conventional impressions.
      This explains why today scanners such as Itero, Cerec Omnicom, and TRIOS that do not use powder present advantages in terms of clinical time and patient comfort compared with conventional impressions.
      The replica technique was used in 12 studies
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      ,
      • Koulivand S.
      • Ghodsi S.
      • Siadat H.
      • Alikhasi M.
      A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time.
      ,
      • Haddadi Y.
      • Bahrami G.
      • Isidor F.
      Accuracy of crowns based on digital intraoral scanning compared to conventional impression—a split-mouth randomised clinical study.
      ,
      • Sakornwimon N.
      • Leevailoj C.
      Clinical marginal fit of zirconia crowns and patients’ preferences for impression techniques using intraoral digital scanner versus polyvinyl siloxane material.
      • Zeltner M.
      • Sailer I.
      • Mühlemann S.
      • Özcan M.
      • Hämmerle C.H.F.
      • Benic G.I.
      Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit.
      • Rödiger M.
      • Heinitz A.
      • Bürgers R.
      • Rinke S.
      Fitting accuracy of zirconia single crowns produced via digital and conventional impressions-a clinical comparative study.
      • Gjelvold B.
      • Chrcanovic B.R.
      • Korduner E.-K.
      • Collin-Bagewitz I.
      • Kisch J.
      Intraoral digital impression technique compared to conventional impression technique. a randomized clinical trial.
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      • Ahrberg D.
      • Lauer H.C.
      • Ahrberg M.
      • Weigl P.
      Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial.
      • Boeddinghaus M.
      • Breloer E.S.
      • Rehmann P.
      • Wöstmann B.
      Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients.
      • Zarauz C.
      • Valverde A.
      • Martinez-Rus F.
      • Hassan B.
      • Pradies G.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions.
      • Pradíes G.
      • Zarauz C.
      • Valverde A.
      • Ferreiroa A.
      • Martínez-Rus F.
      Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.
      ,
      • Syrek A.
      • Reich G.
      • Ranftl D.
      • Klein C.
      • Cerny B.
      • Brodesser J.
      Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling.
      to measure the marginal fit of the crown before cementation. No statistically significant differences were found in terms of the marginal fit of tooth-supported prostheses based on conventional and digital scan techniques. These results are consistent with those reported by Nagarkar et al,
      • Nagarkar S.R.
      • Perdigao J.
      • Seong W.-J.
      • Theis-Mahon N.
      Digital versus conventional impressions for full-coverage restorations: a systematic review and meta-analysis.
      who noted no significant differences between the mean marginal gap values of the 2 techniques. However, the studies included in this review had heterogeneous study designs, the use of different types of restorations or different laboratory fabrication techniques, and the methods used to measure the marginal fit (light microscope, stereomicroscope, macroscope, or explorer). Furthermore, the authors used the silicone replica technique to reproduce the marginal fit. The process requires the manipulation of elastomers that can lead to imprecisions. To avoid this inconvenience, the authors recommended the use of optical coherence tomography, which allows for the measurement of the gap directly on the gypsum casts.
      • Al-Imam H.
      • Michou S.
      • Benetti A.R.
      • Gotfredsen K.
      Evaluation of marginal and internal fit of acrylic bridges using optical coherence tomography.
      Concerning the difficulties of the practitioner in conventional versus digital scan techniques, additional studies are required to assess this aspect.
      • Benic G.I.
      • Sailer I.
      • Zeltner M.
      • Gütermann J.N.
      • Özcan M.
      • Mühlemann S.
      Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: marginal and internal fit.
      ,
      • Berrendero S.
      • Salido M.P.
      • Valverde A.
      • Ferreiroa A.
      • Pradíes G.
      Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns.
      Limitations of this systematic review and meta-analysis included the small number of studies per parameter and the small number of participants included in each study. The evidence level remained low for the studies that were otherwise heterogeneous. Therefore, these results should be interpreted with caution.

      Conclusions

      Based on the findings of this systematic review and meta-analysis, the following conclusions were drawn:
      • 1.
        No statistically significant difference was found between the 2 recording techniques in terms of clinical time.
      • 2.
        Digital scan procedures are more comfortable for patients than conventional impressions.
      • 3.
        Crowns or 3-unit fixed partial dentures fabricated by using intraoral scan techniques are comparable with conventional impressions in terms of their marginal fit.

      Acknowledgments

      The authors thank Carmela Olivia Yankey for her help in translating the article into English.

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