In vitro performance and fracture resistance of CAD/CAM fabricated implant supported molar crowns
ObjectivesThe aim of this study is to investigate the performance and fracture resistance of different CAD/CAM ceramic and composite materials as implant or tooth supported single crowns with respect to the clinical procedure (screwed/bonded restoration).Materials and methodsOne hundred twenty crowns were fabricated on implants or human molar teeth simulating (a) chairside procedure [CHAIR] implant crown bonded to abutment) (b) labside procedure [LAB] abutment and implant crown bonded in laboratory, screwed chairside) and (c) reference [TOOTH] crowns luted on human teeth) Four materials were investigated: ZLS (zirconia reinforced lithium silicate ceramic; Celtra Duo, Degudent: polished (P)/crystallized (C) RB (resin based composite; Cerasmart, GC) and RIC (resin infiltrated ceramic; Enamic, Vita Zahnfabrik) LiS (lithiumdisilicate; Emax CAD, Ivoclar Vivadent) served as reference. Combined thermal cycling and mechanical loading (TCML) was performed simulating a 5 year clinical situation. Fracture force was determined. Data were statistically analyzed (Kolmogorov Smirnov test, one way ANOVA; post hoc Bonferroni, a 0.05).ResultsOne crown of ZLS_C[LAB] (1,200,000 cycles) and RB[CHAIR] (890 cycles) failed during TCML. Fracture values varied between 977.7 N(RB) and 3070.4 N(LiS)[CHAIR] 1130.6 N(RB) and 2998.1 N(LiS)[LAB] and 1802.4 N(ZLS) and 2664.3 N(LiS)[TOOTH] Significantly (p 0.003) different forces were found between the materials in all three groups. ZLS_C, RIC, and RB showed significantly (p 0.014) different values for the individual groups.ConclusionsPartly ceramic and resin based materials performed differently on implant or tooth abutments. The insertion of a screw channel reduced the stability for individual crown materials. Insertion of the screw channel should be performed carefully.Clinical relevanceAll restorations were in a range where clinical application seems not restricted, but insertion of a screw channel might reduce stability of individual materials.
Clinical Oral Investigations