Journal of Prosthetic Dentistry
Systematic Review| Volume 125, ISSUE 5, P732-745, May 2021

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Long-term outcomes of different loading protocols for implant-supported mandibular overdentures: A systematic review and meta-analysis


      Statement of problem

      Evidence provided by implant-supported mandibular overdenture research on different loading protocols is important. However, methodological inconsistency, as well as inadequate reporting of results, hampers a consistent decision in terms of clinical applicability.


      The purpose of this systematic review and meta-analysis was to evaluate whether immediate or early loading protocols can achieve comparable clinical outcomes when compared with a conventional loading protocol in edentulous patients rehabilitated with mandibular overdentures.

      Material and methods

      In accordance with the Participant, Intervention, Comparison, Outcome strategy, prospective clinical studies without restrictions as to language or follow-up period were included. The Cochrane collaboration and ROBINS-I tools were used for quality assessment and risk-of-bias evaluation. The follow-up for the different outcomes ranged from 3 to 168 months, with the focus on implant success and survival rates, marginal bone loss, bleeding on probing, probing depth, plaque index, and the implant stability quotient. Statistical analyses in which standard mean differences were applied with a 95% confidence interval when continuous data were included were performed. For dichotomous data, risk difference was adopted.


      The search strategy resulted in 14 234 references. Twenty-three studies fulfilled the inclusion criteria. Meta-analysis showed statistically significant differences for plaque index at 12 months (standard mean difference=0.284 [0.022, 0.545], P=.033, I2=35%), probing depth at 36 months (standard mean difference=0.460 [0.098, 0.823], P=.013, I2=0%), and on pooled results for plaque index (standard mean difference=0.157 [0.031, 0.284], P=.015, I2=18%) in which the conventional loading protocol presented lower indices than those of immediate loading protocol or early loading protocol. Implant stability quotient presented a statistically significant difference only at 3 months (standard mean difference=0.602 [0.309, 0.895], P<.001, I2=0%) with higher values for the conventional loading protocol. For the other parameters, statistically significant differences (P>.05) were not found.


      Immediate loading protocol or early loading protocolfor mandibular overdentures has been determined to be a well-established treatment and worthy of consideration in clinical practice.
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        • Al-Zubeidi M.I.
        • Alsabeeha N.H.M.
        • Thomson W.M.
        • Payne A.G.T.
        Patient satisfaction and dissatisfaction with mandibular two-implant overdentures using different attachment systems: 5-year outcomes: patient satisfaction and dissatisfaction with mandibular two-implant overdentures using different attachment systems.
        Clin Implant Dent Relat Res. 2012; 14: 696-707
        • Geckili O.
        • Bilhan H.
        • Bilgin T.
        Impact of mandibular two-implant retained overdentures on life quality in a group of elderly Turkish edentulous patients.
        Arch Gerontol Geriatr. 2011; 53: 233-236
        • Passia N.
        • Att W.
        • Freitag-Wolf S.
        • Heydecke G.
        • von Königsmark V.
        • Freifrau von Maltzahn N.
        • et al.
        Single mandibular implant study - denture satisfaction in the elderly.
        J Oral Rehabil. 2017; 44: 213-219
        • Vercruyssen M.
        • Quirynen M.
        Long-term, retrospective evaluation (implant and patient-centred outcome) of the two-implant-supported overdenture in the mandible. Part 2: marginal bone loss.
        Clin Oral Implants Res. 2010; 21: 466-472
        • Zhang S.
        • Wang S.
        • Song Y.
        Immediate loading for implant restoration compared with early or conventional loading: a meta-analysis.
        J Craniomaxillofac Surg. 2017; 45: 793-803
        • Marcello-Machado R.M.
        • Faot F.
        • Schuster A.J.
        • Bielemann A.M.
        • Nascimento G.G.
        • Del Bel Cury A.A.
        How fast can treatment with overdentures improve the masticatory function and OHRQoL of atrophic edentulous patients? A 1-year longitudinal clinical study.
        Clin Oral Implants Res. 2018; 29: 215-226
        • Bielemann A.M.
        • Marcello-Machado R.M.
        • Schuster A.J.
        • Chagas Júnior O.L.
        • Del Bel Cury A.A.
        • Faot F.
        Healing differences in narrow diameter implants submitted to immediate and conventional loading in mandibular overdentures: A randomized clinical trial.
        J Periodontal Res. 2018; 54: 241-250
        • de Souza Batista V.E.
        • Vechiato-Filho A.J.
        • Santiago J.F.
        • Sonego M.V.
        • Verri F.R.
        • dos Santos D.M.
        • et al.
        Clinical viability of single implant-retained mandibular overdentures: a systematic review and meta-analysis.
        Int J Oral Maxillofac Surg. 2018; 47: 1166-1177
        • Banu R.F.
        • Veeravalli P.T.
        • Kumar V.A.
        Comparative evaluation of changes in brain activity and cognitive function of edentulous patients, with dentures and two-implant supported mandibular overdenture-pilot study.
        Clin Implant Dent Relat Res. 2016; 18: 580-587
        • Griffitts T.M.
        • Collins C.P.
        • Collins P.C.
        Mini dental implants: An adjunct for retention, stability, and comfort for the edentulous patient.
        Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005; 100: e81-e84
        • Brånemark P.I.
        • Adell R.
        • Albrektsson T.
        • Lekholm U.
        • Lundkvist S.
        • Rockler B.
        Osseointegrated titanium fixtures in the treatment of edentulousness.
        Biomaterials. 1983; 4: 25-28
        • Roberts W.E.
        • Smith R.K.
        • Zilberman Y.
        • Mozsary P.G.
        • Smith R.S.
        Osseous adaptation to continuous loading of rigid endosseous implants.
        Am J Orthod. 1984; 86: 95-111
        • Junker R.
        • Dimakis A.
        • Thoneick M.
        • Jansen J.A.
        Effects of implant surface coatings and composition on bone integration: a systematic review.
        Clin Oral Implants Res. 2009; 20: 185-206
        • Soares P.B.F.
        • Moura C.C.G.
        • Chinaglia C.R.
        • Zanotto E.D.
        • Zanetta-Barbosa D.
        • Stavropoulos A.
        Effect of titanium surface functionalization with bioactive glass on osseointegration: an experimental study in dogs.
        Clin Oral Implants Res. 2018; 29: 1120-1125
        • Cochran D.L.
        • Morton D.
        • Weber H.-P.
        Consensus statements and recommended clinical procedures regarding loading protocols for endosseous dental implants.
        Int J Oral Maxillofac Implants. 2004; 19: 109-113
        • Gallucci G.
        • Benic G.
        • Eckert S.
        • Papaspyridakos P.
        • Schimmel M.
        • Schrott A.
        • et al.
        Consensus statements and clinical recommendations for implant loading protocols.
        Int J Oral Maxillofac Implants. 2014; 29: 287-290
        • Schimmel M.
        • Srinivasan M.
        • Herrmann F.
        • Müller F.
        Loading protocols for implant-supported overdentures in the edentulous jaw: a systematic review and meta-analysis.
        Int J Oral Maxillofac Implants. 2014; 29: 271-286
        • Alsabeeha N.
        • Atieh M.
        • Payne A.G.T.
        Loading protocols for mandibular implant overdentures: a systematic review with meta-analysis.
        Clin Implant Dent Relat Res. 2009; 12: e28-e38
        • Kawai Y.
        • Taylor J.A.
        Effect of loading time on the success of complete mandibular titanium implant retained overdentures: a systematic review.
        Clin Oral Implants Res. 2007; 18: 399-408
        • Booth A.
        • Clarke M.
        • Dooley G.
        • Ghersi D.
        • Moher D.
        • Petticrew M.
        • et al.
        The nuts and bolts of PROSPERO: an international prospective register of systematic reviews.
        Syst Rev. 2012; 1: 2
        • Moher D.
        • Liberati A.
        • Tetzlaff J.
        • Altman D.G.
        • PRISMA Group
        Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement.
        PLoS Med. 2009; 7: e1000097
        • Roos J.
        • Sennerby L.
        • Lekholm U.
        • Jemt T.
        • Gröndahl K.
        • Albrektsson T.
        A qualitative and quantitative method for evaluating implant success: a 5-year retrospective analysis of the Brånemark implant.
        Int J Oral Maxillofac Implants. 1997; 12: 504-514
        • Sterne J.A.
        • Hernán M.A.
        • Reeves B.C.
        • Savović J.
        • Berkman N.D.
        • Viswanathan M.
        • et al.
        ROBINS-I: a tool for assessing risk of bias in non-randomised studies of.interventions.
        BMJ. 2016; 355: i4919
        • Borenstein M.
        • Hedges L.V.
        • Higgins J.P.T.
        • Rothstein H.R.
        Introduction to meta-analysis.
        1st ed. John Wiley & Sons, Chichester2009: 59-86
        • Ryan R.
        • Hills S.
        How to grade the quality of the evidence. Cochrane Consumers and Communication Group.
        (Available at:)
        • Røynesdal A.K.
        • Amundrud B.
        • Hannaes H.R.
        A comparative clinical investigation of 2 early loaded ITI dental implants supporting an overdenture in the mandible.
        Int J Oral Maxillofac Implants. 2001; 16: 246-251
        • Aunmeungtong W.
        • Kumchai T.
        • Strietzel F.P.
        • Reichart P.A.
        • Khongkhunthian P.
        Comparative clinical study of conventional dental implants and mini dental implants for mandibular overdentures: a randomized clinical trial.
        Clin Implant Dent Relat Res. 2017; 19: 328-340
        • Cannizzaro G.
        • Leone M.
        • Esposito M.
        Immediate versus early loading of two implants placed with a flapless technique supporting mandibular bar-retained overdentures: a single-blinded, randomised controlled clinical trial.
        Eur J Oral Implantol. 2008; 1: 33-43
        • Elsyad M.A.
        • Elsaih E.A.
        • Khairallah A.S.
        Marginal bone resorption around immediate and delayed loaded implants supporting a LOCATOR-retained mandibular overdenture. A 1-year randomized controlled trial.
        J Oral Rehabil. 2014; 41: 608-618
        • Schincaglia G.
        • Rubin S.
        • Thacker S.
        • Dhingra A.
        • Trombelli L.
        • Ioannidou E.
        Marginal bone response around immediate- and delayed-loading implants supporting a LOCATOR-retained mandibular overdenture: a randomized controlled study.
        Int J Oral Maxillofac Implants. 2016; 31: 448-458
        • Zygogiannis K.
        • Aartman I.H.A.
        • Parsa A.
        • Tahmaseb A.
        • Wismeijer D.
        Implant mandibular overdentures retained by immediately loaded implants: a 1-year randomized trial comparing the clinical and radiographic outcomes between mini dental implants and standard-sized implants.
        Int J Oral Maxillofac Implants. 2017; 32: 1377-1388
        • Tawse-Smith A.
        • Payne A.G.T.
        • Kumara R.
        • Thomson W.M.
        Early loading of unsplinted implants supporting mandibular overdentures using a one-stage operative procedure with two different implant systems: a 2-year report.
        Clin Implant Dent Relat Res. 2002; 4: 33-42
        • Assad A.S.
        • Hassan S.A.
        • Shawky Y.M.
        • Badawy M.M.
        Clinical and radiographic evaluation of implant-retained mandibular overdentures with immediate loading.
        Implant Dent. 2007; 16: 212-223
        • Chiapasco M.
        • Abati S.
        • Romeo E.
        • Vogel G.
        Implant-retained mandibular overdentures with Brånemark system MKII implants: a prospective comparative study between delayed and immediate loading.
        Int J Oral Maxillofac Implants. 2001; 16: 537-546
        • Kern M.
        • Att W.
        • Fritzer E.
        • Kappel S.
        • Luthardt R.G.
        • Mundt T.
        • et al.
        Survival and complications of single dental implants in the edentulous mandible following immediate or delayed loading: a randomized controlled clinical trial.
        J Dent Res. 2018; 97: 163-170
        • Payne A.G.T.
        • Tawse-Smith A.
        • Duncan W.D.
        • Kumara R.
        Conventional and early loading of unsplinted ITI implants supporting mandibular overdentures.
        Clin Oral Implants Res. 2002; 13: 603-609
        • Romeo E.
        • Chiapasco M.
        • Lazza A.
        • Casentini P.
        • Ghisolfi M.
        • Iorio M.
        • et al.
        Implant-retained mandibular overdentures with ITI implants: a comparison of 2-year results between delayed and immediate loading.
        Clin Oral Implants Res. 2002; 13: 495-501
        • Stephan G.
        • Vidot F.
        • Noharet R.
        • Mariani P.
        Implant-retained mandibular overdentures: a comparative pilot study of immediate loading versus delayed loading after two years.
        J Prosthet Dent. 2007; 97: S138-S145
        • Turkyilmaz I.
        • Tumer C.
        Early versus late loading of unsplinted TiUnite surface implants supporting mandibular overdentures: a 2-year report from a prospective study.
        J Oral Rehabil. 2007; 34: 773-780
        • Acham S.
        • Rugani P.
        • Truschnegg A.
        • Wildburger A.
        • Wegscheider W.A.
        • Jakse N.
        Immediate loading of four interforaminal implants supporting a LOCATOR-retained mandibular overdenture in the elderly. Results of a 3-year randomized, controlled, prospective clinical study.
        Clin Implant Dent Relat Res. 2017; 19: 895-900
        • Elsyad M.A.
        • Al-Mahdy Y.F.
        • Fouad M.M.
        Marginal bone loss adjacent to conventional and immediate loaded two implants supporting a ball-retained mandibular overdenture: a 3-year randomized clinical trial: Marginal bone loss adjacent to conventional and immediate loaded two implants.
        Clin Oral Implants Res. 2012; 23: 496-503
        • Komagamine Y.
        • Kanazawa M.
        • Sato D.
        • Minakuchi S.
        A preliminary comparison of masticatory performances between immediately loaded and conventionally loaded mandibular two-implant overdentures with magnetic attachments.
        Clin Implant Dent Relat Res. 2019; 21: 130-137
        • Maryod W.H.
        • Ali S.M.
        • Shawky A.F.
        Immediate versus early loading of mini-implants supporting mandibular overdentures: a preliminary 3-year clinical outcome report.
        Int J Prosthodont. 2014; 27: 553-560
        • Ter Gunne L.P.
        • Dikkes B.
        • Wismeijer D.
        • Hassan B.
        • Gunne L.P.
        • Dikkes B.
        • et al.
        Immediate and early loading of two-implant-supported mandibular overdentures: Three-year report of loading results of a single-center prospective randomized controlled clinical trial.
        Int J Oral Maxillofac Implants. 2016; 31: 1110-1116
        • Turkyilmaz I.
        • Tozum T.F.
        • Fuhrmann D.M.
        • Tumer C.
        Seven-year follow-up results of TiUnite implants supporting mandibular overdentures: early versus delayed loading.
        Clin Implant Dent Relat Res. 2012; 14: e83-e90
        • Kourtis S.
        • Madianos P.
        • Patras M.
        • Andrikopoulou E.
        Rehabilitation of the edentulous mandible with implant-supported overdentures on telescopic abutments and immediate loading. A controlled prospective clinical study.
        J Esthet Restor Dent. 2018; 30: 369-377
        • Alfadda S.A.
        • Chvartszaid D.
        • AlFarraj Aldosari A.
        Clinical outcomes of immediately loaded implant-supported overdentures: A long-term prospective clinical trial.
        J Prosthet Dent. 2019; 121: 911-915
        • Lorenzoni M.
        • Pertl C.
        • Zhang K.
        • Wegscheider W.A.
        In-patient comparison of immediately loaded and non-loaded implants within 6 months.
        Clin Oral Implants Res. 2003; 14: 273-279
        • Elsyad M.A.
        • Mahanna F.F.
        • Elshahat M.A.
        • Elshoukouki A.H.
        LOCATORs versus magnetic attachment effect on peri-implant tissue health of immediate loaded two implants retaining a mandibular overdenture: A 1-year randomised trial.
        J Oral Rehabil. 2016; 43: 297-305
        • Pae A.
        • Kim J.-W.
        • Kwon K.-R.
        Immediate loading of two implants supporting a magnet attachment-retained overdenture: one-year clinical study.
        Implant Dent. 2010; 19: 428-436
        • Akça K.
        • Cavusoglu Y.
        • Sagirkaya E.
        • Cehreli M.C.
        Early-loaded one-stage implants retaining mandibular overdentures by two different mechanisms: 5-year results.
        Int J Oral Maxillofac Implants. 2013; 28: 824-830
        • Zinsli B.
        • Sägesser T.
        • Mericske E.
        • Mericske-Stern R.
        Clinical evaluation of small-diameter ITI implants: a prospective study.
        Int J Oral Maxillofac Implants. 2004; 19: 92-99
        • Brägger U.
        • Häfeli U.
        • Huber B.
        • Hämmerle C.H.
        • Lang N.P.
        Evaluation of postsurgical crestal bone levels adjacent to non-submerged dental implants.
        Clin Oral Implants Res. 1998; 9: 218-224
        • Papaspyridakos P.
        • Chen C.-J.
        • Singh M.
        • Weber H.-P.
        • Gallucci G.O.
        Success criteria in implant dentistry: A systematic review.
        J Dent Res. 2012; 91: 242-248
        • Jepsen S.
        • Berglundh T.
        • Genco R.
        • Aass A.M.
        • Demirel K.
        • Derks J.
        • et al.
        Primary prevention of peri-implantitis: managing peri-implant mucositis.
        J Clin Periodontol. 2015; 42: S152-S157
        • Baab D.A.
        • Oberg P.A.
        The effect of cigarette smoking on gingival blood flow in humans.
        J Clin Periodontol. 1987; 14: 418-424
        • Sakallioğlu E.
        • Sakallioğlu U.
        • Lütfioğlu M.
        • Pamuk F.
        • Kantarci A.
        Vascular endothelial cadherin and vascular endothelial growth factor in periodontitis and smoking.
        Oral Dis. 2015; 21: 263-269
        • Marzola R.
        • Scotti R.
        • Fazi G.
        • Schincaglia G.P.
        Immediate loading of two implants supporting a ball attachment-retained mandibular overdenture: A prospective clinical study.
        Clin Implant Dent Relat Res. 2007; 9: 136-143
        • Egger M.
        • Smith G.D.
        • Schneider M.
        • Minder C.
        Bias in meta-analysis detected by a simple, graphical test.
        BMJ. 1997; 315: 629-634
        • Gapski R.
        • Wang H.L.
        • Mascarenhas P.
        • Lang N.P.
        Critical review of immediate implant loading.
        Clin Oral Implants Res. 2003; 14: 515-527