Preparation designs and ceramic materials for premolar veneers: Effects on marginal adaptation and failure load.

PURPOSE: To evaluate the effects of different preparation designs and ceramic materials on the marginal adaptation and failure load of laminate veneer restorations (LVRs) on premolars.

METHODS

Premolar LVRs (0.4 mm thickness) were fabricated using featheredge (F) and butt-joint (B) preparations and four ceramics; Cerec Tessera (CT), Vita Enamic (VE), IPS e.max CAD (EmC), and IPS e.max Press (EmP) (n= 80). Marginal gap (MG) was measured by silicone replica technique. After cementation on epoxy resin dies and 5,000 thermal-cycles, failure load (FL) was tested at the buccal cusp (0.5 mm/minute). Data were analyzed with a two-way ANOVA, Tukey, t-test, (P< 0.05), and fracture types were classified.

RESULTS

Preparation design and ceramic material had statistically significant effects on MG and FL (P< 0.001). B design showed significantly better MG and FL values than F design (P< 0.05). VE exhibited the lowest MG for both preparations, whereas EmP showed the highest MG for B, and EmP and CT for F (P< 0.05). CT showed significantly higher FL than EmP for both preparations (P< 0.05). All failures were catastrophic.

CLINICAL SIGNIFICANCE: The findings of this study provide clinical guidance for the selection of preparation design and ceramic material on premolar LVRs for smile design treatments. The results suggest that butt-joint preparation offers better mechanical strength and marginal adaptation, while CAD-CAM ceramics outperform pressed ceramics.