Minimally invasive vertical preparation design for ceramic veneers: a multicenter retrospective follow-up clinical study of 265 lithium disilicate veneers

The esthetic treatment of the anterior teeth has always presented a challenge in clinical practice. With the improvement of dental materials, many restorative options such as resin composites, all-ceramic crowns, and ceramic veneers have become available. The current challenge in reconstructive dentistry is how to obtain excellent esthetic results while preserving the biological structures involved as much as possible. Thanks to the introduction of high-strength etchable dental ceramics, clinicians and technicians now have materials and procedures at their disposal that allow for the restoration of esthetics and function through a minimally invasive approach. New-generation, all-ceramic restorations and adhesive systems allow greater preservation of residual hard tooth structures, especially with regard to single elements. Purpose: To evaluate the clinical performance of lithium disilicate (LiDiSi) veneers with a feather-edge finish line margin. Materials and methods: A total of 265 LiDiSi veneers were cemented with resin cement after fluoridric acid and silane surface treatment and observed by different clinicians. These veneers were placed in 53 (32 female, 21 male) patients between October 2009 and April 2015, with a mean observation period of 54.4 months. Of these, 211 veneers were placed in the maxilla (77 central incisors, 65 lateral incisors, 49 canines, 12 first bicuspids, 5 second bicuspids, 2 first molars, 1 second molar), and 54 in the mandible (16 central incisors, 14 lateral incisors, 13 canines, 6 first bicuspids, 1 second bicuspid, 2 first molars, 2 second molars). The clinical evaluation used the modified California Dental Association (CDA) and Ryge criteria after recalling all patients between January and March 2017. The clinical parameters evaluated were color matching, quality of the ceramic surface, the presence of marginal discoloration, and marginal integrity. The data were analyzed through descriptive statistical analysis. Results: The clinical survival of the 265 veneers over the follow-up period was 99.63%. One restoration showed adhesive failure due to a traumatic event after 3 years of clinical service. The color matching parameter was classified as Alfa in 93.9% (248/265) and Bravo in 6.4% (17/265) of the restorations, with no Charlie or Delta ratings recorded. The ceramic surface was rated as Alfa in 97.7% (259/265) and Bravo in 2.2% (6/265), marginal discoloration as Alfa in 97.3% (257/265) and Bravo in 3% (8/265), and marginal integrity as Alfa in 96.9% (256/265) and Bravo in 3.4% (9/265) of the restorations. Conclusion: In this retrospective analysis, LiDiSi veneers with a vertical finish line showed good clinical performance in terms of color matching, ceramic surface, marginal discoloration, and marginal integrity. Despite the present results, further clinical studies are needed in order to investigate the long-term performance of this type of restoration.