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Journal of Prosthetic Dentistry

Composite resin CAD-CAM restorations for a midline diastema closure: A clinical report

Published:November 25, 2020DOI:https://doi.org/10.1016/j.prosdent.2020.07.022

      Abstract

      A diastema between the maxillary central incisors affects an esthetic smile and has been treated in various ways. Precise diagnosis is essential to guide the choice of the most appropriate treatment. This clinical report describes closing a maxillary midline diastema with a computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin.
      The presence of space between one or more adjacent teeth is an obstacle to obtaining a proper smile,
      • Anderson K.M.
      • Behrents R.G.
      • McKinney T.
      • Buschang P.H.
      Tooth shape preferences in an esthetic smile.
      • Noureddine A.
      • Fron Chabouis H.
      • Parenton S.
      • Lasserre J.F.
      Laypersons esthetic perception of various computer-generated dia- stemas: a pilot study.
      • Machado A.W.
      10 commandments of smile esthetics.
      • Parini S.
      • Rossini G.
      • Castroflorio T.
      • Fortini A.
      • Deregibus A.
      • Debernardie C.
      Laypeople's perceptions of frontal smile esthetics: a systematic review.
      and maxillary midline diastemas greater than 0.5 mm are classified as malocclusion.
      • Kabbach W.
      • Sampaio C.S.
      • Hirata R.
      Diastema closure: a novel technique to ensure dental proportion.
      ,
      • Sen N.
      • Iselr S.
      Multidisciplinary management of a severe maxillary midline diastema: a clinical report.
      Although for laypeople, spaces around 1.00 mm can be acceptable,
      • Del Monte S.
      • Afrashtehfar K.I.
      • Emami E.
      • Nader S.A.
      • Tamimi F.
      Lay preferences for dentogingival esthetic parameters: a systematic review.
      this clinical condition is a frequent esthetic complaint from patients.
      • Kabbach W.
      • Sampaio C.S.
      • Hirata R.
      Diastema closure: a novel technique to ensure dental proportion.
      ,
      • Baum A.T.
      The midline diastema.
      • Bernabe E.
      • Flores-Mir C.
      Influence of anterior occlusal characteristics on self-perceived dental appearance in young adults.
      • Spear F.M.
      • Kokich V.G.
      A multidisciplinary approach to esthetic dentistry.
      The etiology of diastemas may include an atypical upper lip frenulum attachment, a discrepancy in the shape or size of teeth, agenesis of the lateral incisors, periodontal disease, and hereditary or ethnic characteristics.
      • Sen N.
      • Iselr S.
      Multidisciplinary management of a severe maxillary midline diastema: a clinical report.
      ,
      • Chu C.H.
      • Zhang C.F.
      • Jin L.J.
      Treating a maxillary midline diastema in adult patients: a general dentist’ s perspective.
      • Lin W.S.
      • Harris B.T.
      • Phasuk K.
      • Llop D.R.
      • Morton D.
      Integrating a facial scan, virtual smile design, and 3D virtual patient for treatment with CAD-CAM ceramic veneers: a clinical report.
      • Barros de Campos P.R.
      • Maia R.R.
      • Menezes L.R.
      • Barbosa I.F.
      • Carneiro da Cunha A.
      • da Silveira Pereira G.D.
      Rubber dam isolation key to success in diastema closure technique with direct composite resin.
      An appropriate treatment plan may involve multiple dental specialties.
      • Kabbach W.
      • Sampaio C.S.
      • Hirata R.
      Diastema closure: a novel technique to ensure dental proportion.
      ,
      • Sen N.
      • Iselr S.
      Multidisciplinary management of a severe maxillary midline diastema: a clinical report.
      ,
      • Barros de Campos P.R.
      • Maia R.R.
      • Menezes L.R.
      • Barbosa I.F.
      • Carneiro da Cunha A.
      • da Silveira Pereira G.D.
      Rubber dam isolation key to success in diastema closure technique with direct composite resin.
      ,
      • Romero M.F.
      • Babb C.S.
      • Brenes C.
      • Haddock F.J.
      A multidisciplinary approach to the management of a maxillary midline diastema: a clinical report.
      Orthodontic correction, even though the most conservative treatment, presents difficulties because of a tooth-shape discrepancy,
      • Bolton W.A.
      Disharmony in tooth size and its relation to the analysis and treatment of malocclusion.
      • Bolton W.A.
      The clinical application of a tooth-size analysis.
      • Wise R.J.
      • Nevins M.
      Anterior tooth site analysis (Bonton Index): how to determine anterior diastema closure.
      which can result in residual space at the end of treatment.
      • Barros de Campos P.R.
      • Maia R.R.
      • Menezes L.R.
      • Barbosa I.F.
      • Carneiro da Cunha A.
      • da Silveira Pereira G.D.
      Rubber dam isolation key to success in diastema closure technique with direct composite resin.
      ,
      • Romero M.F.
      • Babb C.S.
      • Brenes C.
      • Haddock F.J.
      A multidisciplinary approach to the management of a maxillary midline diastema: a clinical report.
      ,
      • Signore A.
      • Kaitsas V.
      • Tonoloni A.
      • Angiero F.
      • Silvestrini-Bavati A.
      • Benedicenti S.
      Sectional porcelain veneers for a maxillary midline diastema closure: a case report.
      ,
      • Saratti C.M.
      • Krejci I.
      • Rocca G.T.
      Multiple diastema closure in periodontally compromised teeth: how to achieve an enamel-like emergence profile.
      In addition, orthodontic treatments can be prolonged and, therefore, declined as an option by some patients, especially adults.
      • Kabbach W.
      • Sampaio C.S.
      • Hirata R.
      Diastema closure: a novel technique to ensure dental proportion.
      ,
      • Signore A.
      • Kaitsas V.
      • Tonoloni A.
      • Angiero F.
      • Silvestrini-Bavati A.
      • Benedicenti S.
      Sectional porcelain veneers for a maxillary midline diastema closure: a case report.
      Direct composite resins are often used to close diastemas
      • Kabbach W.
      • Sampaio C.S.
      • Hirata R.
      Diastema closure: a novel technique to ensure dental proportion.
      ,
      • Barros de Campos P.R.
      • Maia R.R.
      • Menezes L.R.
      • Barbosa I.F.
      • Carneiro da Cunha A.
      • da Silveira Pereira G.D.
      Rubber dam isolation key to success in diastema closure technique with direct composite resin.
      ; however, the material may not be color stable, and obtaining an emergence profile without creating a step close to the gingival margin is challenging.
      • Calamia V.
      • Pantzis A.
      Simple case treatment planning: diastema closure.
      Thus, the use of a computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin is an excellent option, as it presents advantages when compared with direct restorations and even in relation to partial ceramic veneers.
      • Lebon N.
      • Tapie L.
      • Vennat E.
      • Mawussi B.
      Influence of CAD/CAM tool and material on tool wear and roughness of dental prostheses after milling.
      ,
      • Mainjot A.K.J.
      The one step-no prep technique: a straightforward and minimally invasive approach for full-mouth rehabilitation of worn dentition using polymer-infiltrated ceramic network (PICN) CAD-CAM prostheses.
      While dental ceramics can be easily etched, predictably bonded, color stable, and wear resistant,
      • Signore A.
      • Kaitsas V.
      • Tonoloni A.
      • Angiero F.
      • Silvestrini-Bavati A.
      • Benedicenti S.
      Sectional porcelain veneers for a maxillary midline diastema closure: a case report.
      ,
      • Peumans M.
      • Van Meerbeek B.
      • Lambrechts P.
      • Vanherle G.
      Porcelain veneers: a review of the literature.
      the properties of the CAD-CAM composite resins enable thin designs, with less possibility of chipping of the margins and less milling time than ceramics.
      • Lebon N.
      • Tapie L.
      • Vennat E.
      • Mawussi B.
      Influence of CAD/CAM tool and material on tool wear and roughness of dental prostheses after milling.
      ,
      • Mainjot A.K.J.
      The one step-no prep technique: a straightforward and minimally invasive approach for full-mouth rehabilitation of worn dentition using polymer-infiltrated ceramic network (PICN) CAD-CAM prostheses.
      ,
      • Tsitrou E.A.
      • van Noort R.
      Minimal preparation designs for single posterior indirect prostheses with the use of the Cerec system.
      • Schlichting L.H.
      • Maia H.P.
      • Baratieri L.N.
      • Magne P.
      Novel-design ultra-thin CAD/CAM composite resin and ceramic occlusal veneers for the treatment of severe dental erosion.
      • Awada A.
      • Nathanson D.
      Mechanical properties of resin-ceramic CAD/CAM restorative materials.
      • Schlichting L.H.
      • Magne P.
      Double-milled CAD-CAM composite resin restorations: a proof-of-concept approach to producing histo-anatomic bilaminar restorations.
      In addition, they can be repaired and characterized easily.
      • Schlichting L.H.
      • Magne P.
      Double-milled CAD-CAM composite resin restorations: a proof-of-concept approach to producing histo-anatomic bilaminar restorations.
      This clinical report describes the replacement of composite resin direct restorations for maxillary midline diastema closure with indirect CAD-CAM composite resin restorations.

      Clinical report

      A 25-year-old woman, without significant medical history, attended a private dental office concerned about the esthetics of her smile and recurrent gingival inflammation (Fig. 1). The clinical examination showed aged restorations with rough surfaces and disharmony with the contour of the surrounding tissues, creating oral hygiene difficulties. She had an Angle Class I occlusion, absence of carious lesions, and good periodontal condition, except in the region of the maxillary midline papilla. The gingival margins of the maxillary lateral incisors were asymmetric as seen in Figure 1B.
      • Mattos C.M.
      • Santana R.B.
      A quantitative evaluation of the spatial displacement of the gingival zenith in the maxillary anterior dentition.
      The radiographs revealed a lack of symmetry of the mesiodistal widths of the maxillary central incisors, causing the diastema that had been restored with composite resin. After the advantages and disadvantages of different treatment options had been explained, she opted for composite resin CAD-CAM restorations.
      Figure thumbnail gr1
      Figure 1Patient dissatisfied with her smile esthetics. Aged restorations with rough surfaces and improper contour caused gingival inflammation. A, Smile view. B, Intraoral frontal view.
      Maxillary and mandibular impressions were made with irreversible hydrocolloid (HydroPrint Premium; Coltène) and poured with Type IV dental stone (Fuji Rock; GC Corp) to make trays for at-home bleaching with 16% carbamide peroxide (Coltène) for 4 hours a day for 20 days.
      A tungsten carbide bur (H283; Komet Dental) was used to remove the existing restorations, exposing a 3.0-mm midline diastema. The mesiobuccal line angles were slightly flattened with abrasive paper disks (SofLex; 3M 3Oral Care) to smooth the transition between the tooth and the definitive restoration (Fig. 2). A 2-step impression was made with polyvinyl siloxane (President The Original Putty Super Soft + President The Original Light Body; Coltène) by using the double cord technique (#000 + #1 Ultrapak; Ultradent Products, Inc), and solid definitive casts
      • Magne M.
      • Bazos P.
      • Magne P.
      The alveolar model.
      were poured with Type IV dental stone (Fuji Rock; GC) to reduce the amount of dimensional distortion.
      • Anusavice K.J.
      • Shen C.
      • Rawls H.R.
      Phillips’ science of dental materials.
      The gingival design and emergence angles in the maxillary midline papilla were reshaped on the stone cast, and the indirect restorations were planned to optimize soft tissue contour.
      • Clavijo V.
      • Sartori N.
      • Phark J.H.
      • Duarte Jr., S.
      Novel guidelines for bonded ceramic veneers: Part 1. Is tooth preparation truly necessary?.
      The casts were scanned (TRIOS 4; 3Shape A/S), and the restorations were designed by using a software program (exocad dental CAD; exocad GmbH) (Fig. 3). After she had approved the restoration designs, they were milled from composite resin blocks (Brilliant Crios HT A1; Coltène) (Fig. 4).
      Figure thumbnail gr2
      Figure 2After removing previous restorations, mesiobuccal line angles flattened with abrasive disks (SofLex; 3M).
      Figure thumbnail gr3
      Figure 3Contour of restorations developed digitally (exocad Dental CAD).
      Figure thumbnail gr4
      Figure 4Stone cast and milled composite resin restorations evaluated after finishing and polishing.
      Before definitive adhesive luting, the intaglio surfaces of the partial veneers were airborne-particle abraded with aluminum oxide (25 to 50 μm at 0.15 MPa), followed by the application of a thin layer of universal adhesive (One Coat 7; Coltène) and left unpolymerized.
      • Spitznagel F.A.
      • Vuck A.
      • Gierthmuhlen P.C.
      • Blatz M.B.
      • Horvath S.D.
      Adhesive bonding to hybrid materials: an overview of materials and recommendations.
      A dental dam was placed, and the enamel was airborne-particle abraded with aluminum oxide (25 to 50 μm at 0.15 MPa). The maxillary central incisors were conditioned with 37% phosphoric acid (Magic Acid; Coltène) for 30 seconds, washed with water, and dried with air jets. A thin layer of universal adhesive (One Coat 7; Coltène) was applied, the excess removed with a gentle air stream, and the adhesive left unpolymerized.
      The luting agent, a microhybrid composite resin (Brilliant EverGlow BL Trans; Coltène), was preheated to 69 °C (CalsetTM; AdDent Inc). The veneers were also preheated, the luting agent placed, and the veneers seated with ultrasonic vibration (Pyon 2; W&H) and light polymerized for 20 seconds (Valo; Ultradent Products, Inc) as seen in Figure 5. Abrasive paper disks (SofLex; 3M) and a polishing system (Diacomp Plus; EVE, American Inc) were used to finish the restorations.
      Figure thumbnail gr5
      Figure 5Restorations bonded with dental dam isolation.
      After removing the dental dam, the gingival margin of the maxillary right lateral incisor was repositioned through a flapless crown lengthening procedure.
      • Joly J.C.
      • Mesquita C.P.F.
      • Carvalho S.R.
      Flapless aesthetic crown lengthening: a new therapeutic approach.
      The height of the alveolar bone crest was reduced through osteoplasty with a microchisel (Ochsenbein; Hu-Friedy) (Fig. 6).
      Figure thumbnail gr6
      Figure 6After flapless crown lengthening of right lateral maxillary incisor. Height of alveolar bone crest recontoured with microchisel (Ochsenbein; Hu-Friedy)
      One week later, soft tissue healing and repositioning of the maxillary midline papilla was observed. The esthetics and contour of the restorations and the periodontium were satisfactory (Fig. 7).
      Figure thumbnail gr7
      Figure 7Healthy periodontal tissue after 7 days. A, Intraoral frontal view. B, Smile view.

      Summary

      The direct composite restorations had unsatisfactory contours, had worn, and were associated with an unaesthetic gingival contour and maxillary midline papilla. The stone casts allowed a modification of the gingival architecture so that indirect restorations could be designed for this revised architecture, achieving an improved emergence profile. The choice of CAD-CAM composite resin permitted veneers with minimal thickness, ensuring periodontal tissue health.

      Acknowledgments

      The authors thank MW Dental Studio CDT, Rio de Janeiro, Brazil for the definitive restorations.

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