INVESTIGATION THE EFFECT OF RESTORATIONS FABRICATED WITH CAD/CAM TECHNOLOGY, THE HEAT-PRESS TECHNIQUE, AND TYPE OF RESIN CEMENT ON MARGINAL AND INTERNAL ADAPTATION OF ALL CERAMIC CROWNS.

Statement of the problem: the use of pressable and CAD/CAM ceramics have been lately frequently used in fixed prosthodontics. However, information about their marginal fit and internal adaptation are is little. Purpose: Marginal adaptation and internal adaptation are an important factor affecting the longevity of all ceramic restorations, so the purpose of the study was to evaluate the effect of restorations fabricated with CAD/CAM technology, the heat-press technique ceramic and luting agent on the Marginal Fit and Internal Adaptation of all Ceramic crowns. Materials & methods: A total of 20 mandibular Second premolars teeth were used in this study and divided into two groups according to technique of fabrication of ceramic crowns as follow: Machinable ceramics (M). IPS E-max CAD blocks have used for fabrication of ceramic crowns. (n=10), Pressable ceramics (P). IPS E-max press ingots have used for fabrication of ceramic crowns. (n=10).Each group is divided into two subgroups according to the type of resin cement used as follow: Group T: Ceramic crowns are cemented with total etch Cement-it resin cement (n=5). Group S: Ceramic crowns are cemented with Rely-x self-adhesive resin cement (n=5).A silicone replica was obtained to measure marginal and internal adaptation of each all-ceramic crown before luting, and they were sectioned vertically in mesiodistal direction. Marginal and internal adaptations were measured using computerized light microscope at 100 × magnification. Data were presented as mean and standard deviation (SD) values. Regression model with repeated measures Analysis of Variance two ways (ANOVA) was used in testing significance for the effect of ceramic type and cement type. Results: related to marginal gap, it was found that press group recorded statistically significant (P<0.05) higher vertical marginal gap mean value (55.07 ± 1.1 ?m) than CAD group (49.99± 5.57 ?m) as indicated by two way ANOVA followed by pair-wise Tukey’s post-hoc tests. it was found that vertical marginal gap mean value of self-adhesive cement was statistically non-significant (P>0.05) higher (54.77± 0.8 ?m) than total etch cement (50.3± 5.88 ?m).while related to internal adaptation, totally it was found that CAD group recorded statistically significant (P<0.05) higher internal gap mean value (87.45 ± 15.4 ?m) than press group (36.64± 5.15 ?m) and it was found that internal gap mean value of total etch cement was statistically significant (P<0.05) higher (67.24± 11.14 ?m) than self-adhesive cement (56.85± 9.4 ?m). Conclusion: Within the limitation of this study, The CAD group recorded statistically significant high vertical marginal fit than press group. The cement type has no effect on the marginal fit. The press group recorded statistically significant high internal fit than CAD group.