Objectives: There are many ways to produce all-ceramic crowns. Computer-aided design and computer-aided manufacturing (CAD/CAM) procedures compete against conventional fabricated restorations. As different methods of production may produce variable results, this study aims to compare chairside and laboratory-based CAD/CAM systems to conventional crowns regarding their similarity to original tooth morphology, number of occlusal contacts, occlusal adjustment time, and subjective aesthetic perception.
Material and methods: Impressions of caries-free jaws were taken, and the resulting gypsum casts were scanned with a laboratory scanner. Preparations for all-ceramic full crowns were performed on first molars, and three different restorations were made: CEREC restorations (CER), laboratory-produced CAD/CAM crowns (LABCAD), and conventional waxed-up/pressed ceramic crowns (CONV). Time for occlusal adaptation and the number of occlusal contacts were noted. Two dentists performed aesthetic gradings of restorations. Statistical analysis included one-way ANOVA with least significant difference (LSD) post hoc test, t test, and Kruskal-Wallis test.
Results: Metrical deviations of the re-scanned crowns to the original, unprepared tooth surface were 220.55 ± 54.31 μm for CER, 265.94 ± 61.39 for LABCAD, and 252.44 ± 68.77 μm for CONV group. One-way ANOVA showed significant lower deviations for the CER group. LABCAD crowns showed significantly more occlusal contacts, whereas CONV crowns required the least time for occlusal adaptation and showed excellent aesthetic gradings.
Conclusion: All three methods had pros and cons regarding different parameters. Further improvements of CAD/CAM software shall lead to restorations comparable to conventional restorations in all aspects, especially in aesthetics.
Clinical relevance: All tested methods of production for all-ceramic crowns produced clinically acceptable results. Thus, in an individual case, the method chosen can be determined by the dentist's preference.
Keywords: CAD/CAM; Crowns; Morphology; Occlusion.