Methods: Practice-based controlled clinical trial, 23 dentists, 91 monolithic ceramic test restorations (BruxZir, e.maxCAD 12.5min processing and 27min processing) and control (Swiss SF PressCeram veneer over Metoxit zirconia). Graded in vivo: margins, contacts, esthetics, plaque retention, gingival health, caries, sensitivity, endo, retention. Graded in vitro (gold sputtered dies 8x, SEM images, measurement instrumentation): cracks, chips, breaks, wear, glaze durability, wear facets on opposing dentition from crowns and on crowns from opposing dentition. Statistics: Test of proportions and ANOVA.
Results: 97% 2-year recall.
Test Crowns: No cracks, breaks, or overall wear; 1% chips, 1% surface degradation.
Control Crowns: No overall wear or surface degradation; 6% cracks, 6% chips, 35% breaks requiring replacement.
Test and Control Crowns:
(1) Crown materials all wore opposing dentition ≥90%. Wear facet progression year 1-2: BruxZir 6%, PressCeram and e.maxCAD 27min 4%, e.maxCAD 12.5min 3% (p=0.6235). Overall mean facet area increase year 1-2: 4.3%.
(2) Opposing materials (amalgam, composite, enamel, cast gold, porcelain) all wore BruxZir with enamel worst at 100%. E.maxCAD 12.5 min not worn by amalgam or composite, porcelain worst at 100%. E.maxCAD 27min not worn by composite, gold worst at 100%. PressCeram not worn by amalgam, porcelain worst at 100%. Overall mean facet area increase year 1-2: 4.2%.
(3) Glaze loss e.maxCAD 27min 4%, e.maxCAD 12.5min 13%, PressCeram 14%, BruxZir 29%.
Graded variables with no problems and no differences: margins, contacts, plaque retention, gingival health, caries, sensitivity, endo, retention, e.maxCAD 12.5min vs. 27min processing.
Conclusions: At 2 years full zirconia and lithium-disilicate CAD-CAM monolithic restorations had 100% clinical survival which was statistically superior (p=<0.001) to control crowns at 63% survival. With all materials tested occlusal wear facets were present in both directions, but were small and shallow.