29 January 2020

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CAD/CAM or conventional ceramic materials: which last longer?

Co-author: Allegra Comba

Lorenzo Breschi

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When discussing about restorative dentistry and prosthodontics, rehabilitations with CAD/CAM high performance materials are an alternative to traditional techniques because of the easy accessibility of chairside fabrication of the final restoration.
Use of CAD/CAM technology has become more and more common in recent years, with an increased number of bridges, crowns, onlays, and inlays placed every year. Furthermore, there has been a considerable increment in the number of available chairside systems and one of the main reasons for this is that intraoral scanners have become increasingly better, smaller, and faster, while the design software has become more and more user-friendly. Many work steps are now automated, and a very large range of materials is now available for dental chairside applications. However, even if CAD/CAM technology has significantly improved over time and has been shown to be more time efficient in ceramic prosthesis fabrication than the conventional method, other factors like adaptation and quality of the manufactured should be taken into consideration.

A recent review by Becker Rodrigues et al, from Brazil, reported that the estimated five-year survival of all-ceramic crowns ranges between 90.7% and 96.6% (feldspathic/silica based ceramics and leucite or lithium-disilicate reinforced glass ceramics), whereas the clinical performance of CAD/CAM single tooth restorations is attested around 91.6% after five years. In that context, the purpose of the research conducted by the group of the Federal University of Rio Grande do Sul was to evaluate the longevity of conventional and CAD/CAM techniques for tooth-supported ceramic prosthesis (single crown, multipleunit or partial ceramic crown) and to identify the complication types associated with the main clinical outcomes.

MATERIALS AND METHODS
The authors included in the review and meta-analysis only studies evaluating the survival of milling or CAD/ CAM prostheses after a minimum of two years of follow-up time. Two reviewers independently assessed the titles and abstracts of all of the selected articles. The articles were first reviewed by title and abstract and subsequently by a full text reading. Electronic database searches from all sources (PubMed, SCOPUS, LILACS and Web of Science) identified 1897 publications. After evaluating the titles and abstracts, 159 publications were selected for full text reading. In the end, fourteen studies (published between 1966 to October 10th, 2017) were included in the systematic review and seventeen comparisons groups were included in the meta-analysis (one publication presented one test and three control groups). This interesting paper provided an overview on the longevity of ceramic restorations according to techniques (conventional or CAD/CAM) using a tooth-supported single crown, multiple-unit and partial single crown.

RESULTS
The result obtained suggested that CAD/CAM system resulted in more chances to fail compared to conventional manufacturing of a ceramic restoration, considering losses of follow-up as failures or as successes. Furthermore, the results of the meta-analysis suggested that the longevity of tooth-supported single crown, multiple unit or partial ceramic crowns made by CAD/CAM is lower than that of crowns made by conventional techniques.

CONCLUSIONS
The authors concluded that the material type and process were the most frequent reasons for CAD/CAM failures and suggest a more in-depth analysis to evaluate the difference between CAD/CAM generations and software limitations to elucidate the reasons that CAD/CAM results in a higher risk of failure.  

(Photocredit: Dr Edoardo Mancuso, Dr Emanuele Bergantin)

For more information: CAD/CAM or conventional ceramic materials restorations longevity: a systematic review and meta-analysis.