Quintessence of Dental Technology 2021-2022

Volume 44
1. Auflage 2022
ISBN: 978-1-64724-132-2
Verlag: Quintessence Publishing Co, Inc
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, Band 44, 256 Seiten

Reihe: Volume

QDT 2021-2022 introduces new digital concepts and novel treatment strategies that are sure to inspire the laboratory technician and restorative clinician. Original articles describe the digital alveolar support technique, digital impression strategies for more predictable final restorations, a modified All-on-4 concept that retains teeth for natural dentofacial esthetics, and a new crown-lengthening approach for optimal soft tissue healing. 'Biomaterials Update' explores gradient multilayered zirconia for expanding the indication of monolithic zirconia to the esthetic zone. These are but a sampling of the information-packed articles in this beautifully produced annual publication.

Dr. Sillas Duarte, Jr., is associate professor and Chair, Division of Restorative Sciences, Ostrow School of Dentistry University of Southern California, Los Angeles, California. Dr. Duarte is the Director of the Advanced Program in Operative Dentistry at USC and the Editor-in-Chief of Quintessence of Dental Technology (QDT). Dr. Duarte has served on the editorial boards of other journals, and has lectured and performed hands-on courses nationally and internationally on esthetic dentistry and adhesion. He has been involved in teaching cutting-edge clinical techniques and technologies related to aesthetic and adhesive dentistry. Dr. Duarte's scientific work has been supported by governmental and commercial grants and he serves as a consultant for several manufacturers. His research and clinical work focus on bonding to dental structures, composites, and ceramics.

Leseproben

Masterpiece Healing Guided by Design: The Crown-Lengthening Procedure Revisited Eric Van Dooren, DDS1 Florin Cofar, DDS2 Ioana Popp, CDT2 Ioan Cofar, DDS2 Marcelo Giordani, DDS3 Gustavo Giordani, DDS4 Victor Clavijo, DDS, MS, PhD5 1Private Practice limited to prosthodontics, implants, and periodontal plastic surgery, Antwerp, Belgium. 2DENTCOF, Timisoara, Romania. 3Alpha-Alpha Taboré Odontologia, São Paulo, Brazil. 4Studio Giordani, São Paulo, Brazil. 5Private Practice, Indaiatuba, Brazil; Visiting Professor, Advanced Program in Operative and Restorative Dentistry, Division of Restorative Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA. Correspondence to: Dr Eric Van Dooren, Tavérnierkaai 2, 2000 Antwerp, Belgium. Email: [e-mail] The success of any anterior implant surgery comes partly from the surgical procedure and partly from the prosthetic design to support the tissue. This lesson learned from implant dentistry can be important in terms of rethinking how we manage natural teeth scenarios. Unlike implants, in which the provisional or final restorations are used to guide the soft tissue during healing, dental restorations are placed in fully healed periodontal tissues. This means that once a crown-lengthening surgery is performed, it seldom has the final prosthetic restorative support—and no restorative guidance or limited provisional guidance. The final restoration is then fabricated after the periodontal healing phase. This reactive approach to tissue healing often leads to modifications in the restoration design to accommodate the changes that occurred during the healing process. Due to advancements in digital dentistry, specifically in the speed of manufacturing and library-based design, which allow a more consistent and predictable fabrication of well-designed restorations, a new narrative is emerging: the use of digital design based on natural teeth morphology, similar to the way it currently is used for implant-supported restorations. Library-based design can be used to support and act as a scaffold of healing for both crown lengthening and grafting procedures. It allows less invasive crown-lengthening techniques. The following case describes and illustrates an innovative crown-lengthening approach guided by the final restorative design for optimal healing of the periodontal tissues. PATIENT PRESENTATION Fig 1 The patient presented with traumatized maxillary anterior dentition with fractures and cracks in addition to uneven gingival tissues. Fig 2 Left and right preoperative views. The maxillary central incisors previously suffered trauma and were restored with composite resin. The existing tooth shape is inadequate and crown length too short. To adequately restore the morphology of the maxillary anterior teeth, soft and hard tissue management was necessary. Fig 3 Endodontic treatment immediately after trauma (Dr Alexander Schryvers, Antwerp, Belgium). Fig 4 CBCT evaluation of the maxillary anterior teeth. DIGITAL DESIGN Design in Smilecloud is, in essence, an artificial intelligence (AI)-powered natural shapes search engine that is able to render unique compositions into virtual lifelike smile designs. It has a double value: (1) for communication with both the patient and the technician, acting like a visual order system, and (2) for searching shapes that match 3D without the need for extensive adjustments, thus maintaining natural morphology. Fig 5 The patient’s images were uploaded in a digital design tool (Smilecloud software, www.smilecloud.com). The evaluation of the ideal tooth shape for the maxillary anterior teeth revealed the need for crown lengthening, but more specifically provided the amount of crown lengthening required for each tooth. The algorithm in the software uses a selection of natural tooth forms, and the goal during treatment was to keep the natural tooth forms selected by the algorithm for all maxillary anterior teeth to serve as a guide for both clinical crown lengthening and prosthetic design. This reverse planning allowed for precise, fast, and predictable treatment. The final goal was to complete the treatment—from initial documentation to bonding of the final restorations—within 5 business days. CROWN LENGTHENING Fig 6 After the patient was anesthetized, the amount of crown lengthening was measured clinically following the digital design. Clinical decision-making for crown lengthening will depend on many factors, such as remaining attached gingival tissue after surgery (minimally 2 to 3 mm); presence of enamel, dentin, or root surface as a bonding surface; and the future zenith position. On the CBCT it was evident that after crown lengthening of the right lateral incisor, the bonding surface would remain on enamel. However, the root surface of both central incisors could be exposed. Fig 7a For the two central incisors, a probing perforation was done at the new zenith level. Fig 7b Gingivectomy was accomplished with an internal beveled incision (no. 15 scalpel) performed at the facial aspect of the involved teeth and following the digitally designed gingival contour to create a new gingival zenith and outline. Figs 7c and 7d Thick retraction cord is used to displace the gingiva and form the new gingival contour. Fig 7e Probing is also performed on the right lateral incisor. For this tooth specifically, the new approach will be used. Fig 7f The technique involves using a releasing incision to connect the existing zenith with the future zenith, followed by flapless bone recontouring. This technique can be used up to a maximum of 1.5 mm. Fig 7g Thick retraction cord (Pascal #9) is used to displace the tissue and allow the operator to achieve the preparation finishing margin location according to the digital design. Fig 8 Frontal view after clinical crown lengthening with retraction cords in place and before initial preparation. Note the immediate improvement of the gingival architecture and teeth proportions. TEETH PREPARATION Fig 9 Preparation finishing margins should follow the library design and not the displaced soft tissue. When the provisional or final restoration is in place, the displaced tissue will migrate interproximally, allowing for a better papillae/gingival line angle relationship from a sagittal perspective and papillae/contact area relationship from a frontal perspective. Fig 10 After final preparation, the new biologic width was restored by osteotomy and osteoplasty using a piezoelectric device (CVDentus, CVD Vale). This procedure is done in a flapless, atraumatic, and non-invasive way as possible in order to have minimal trauma and fast healing. A distance of 3.0 mm between the bone crest and cementoenamel junction (CEJ) was obtained. Fig 11 Final preparations with retraction cords in place and after the design-guided crown-lengthening procedure. During the preparation it is important to keep the finishing margins supragingival at the mesial and distal line angles of the preparation; the zenith is the only area that should be intrasulcular. This will maintain the integrity of the soft tissue and papillae. Both digital and polyvinyl siloxane impressions were made. Fig 12 Occlusal view of the final preparations. Note the difference between the central incisors with gingivectomy and the right lateral incisor with the minimal vertical incision. FABRICATION OF RESTORATIONS Fig 13 Provisional restorations based on the design were fabricated to keep the gingival tissue at the expected location and allow for initial healing. The patient is asked to brush with high concentration of active oxygen gel (Blue M, Blue M Care) at the restorative-periodontal interface. Note the color difference between the central and lateral incisors as a result of the difference in material thickness and substrate shade. The slight discoloration of the teeth needs to be addressed when fabricating the monolithic restorations. Fig 14 Using the initial design, leucite-reinforced glass-ceramic veneers were milled (Empress CAD Multi, Ivoclar Vivadent). Note the gingival contour of the right lateral incisor veneer (highlighted in blue). The details and precision of the milling following the initial digital design will condition the healing and positioning of the marginal soft tissue after bonding. Fig 15 Monolithic CAD/CAM restorations were finished, stained, and polished. Fig 16a Preoperative situation of right lateral incisor. Fig 16b Day 1: Crown lengthening (incision with flapless osseous correction) and preparation. Fig 16c Day 4: Initial healing of soft tissue and after removal of the provisional bridge...