The quantitative evaluation of process dependent internal adaptation of zirconia crown copings is an important aspect in dentistry. Particularly with regard to the utilized materials for replica production internal adaptation is important for reconstructions with an adequate lifetime. Until now, limited data on these topics have been reported. Aim of this study was to evaluate the process dependent internal adaptation of zirconia crown copings using different materials for replica production.
Methods:
A metal master die of maxillary first right molar was manufactured and 15 silicone impressions were taken. Adjacent master casts of each impression were produced with a standardized procedure using different materials (n=5) (Implantat-Rock (A), Picodent_camtec-rock (B), Esthetik_Base_Gold (C), Superstone_Nature (D), Modralit_3K (E)). Afterwards master casts were scanned with an optical scanner (CEREC inLab). The data were input to a computer and the crown copings were designed using the CEREC tooth database. Presintered zirconia blocks were milled in the CAM unit. The internal adaptation was evaluated by a replica technique. After removal from the master casts, the replicas were segmented, and measurements of the film thickness were performed with a light microscope. Descriptive statistics and a one‑way analysis of variance with Bonferroni adjustment was used to analyze the differences in the inernal gap (Alpha=0.005).
Results:
The internal adaptation of zirconia crown copings regarding different replica materials are (Material:mean,SD,Min,Max)[µm]: (A:102,58,1,1752);(B:95,50,4,1235);(C:106,66,3,1234);(D:95,45,7,286);(E:96,60,4,1524). Significant differences could only be detected between the materials A vs. B,C,D,E and B vs. C and C vs D,E.
Conclusions:
Within the limitations of this in vitro – study, following conclusions were drawn: The mean internal adaptation was in a clinical acceptable range when the aforementioned materials were used.