MARGINAL ADAPTATION OF VARIOUS CAD/CAM ALL-CERAMIC SUPERSTRUCTURES CEMENTED ON READY AND CUSTOM MADE ZIRCONIA ABUTMENTS

Statement of the problem: In spite of the varied materials and techniques available for fabricating implant-supported superstructures, reaching an abutment/crown combination that provides standardized results and an accurate fit is still of utmost importance for the success of implant-supported restorations.
Purpose of the study: This study aimed to evaluate the marginal adaptation of various CAD/CAM fabricated all-ceramic superstructures cemented on both ready and custom made zirconia abutments.
Materials and methods: A total of 30 implant samples were divided into two main groups (n=15) according to the received zirconia abutment design as follows; Group I: readymade zirconia abutments with scalloped 0.5 mm chamfer finish line and Group II: custom made zirconia abutments with uniform 1mm deep chamfer finish line. According to the received ceramic superstructure material each group was further subdivided into three subgroups (n=5) namely; subgroup1: Vita Enamic, subgroup2: IPS e. max CAD and subgroup3: Zirconia. Vertical marginal gap measurements for different groups were carried before cementation using a digital microscope; measurements were repeated again after cementation of the superstructures each on its corresponding abutment. Data were statistically analyzed.
Results: Regardless of ceramic superstructure material or cementation, it was found that the ready-made abutments recorded a statistically significant higher mean vertical marginal gap than the custom made abutments. Regardless of abutment designs or superstructure material; it was found that there was a statistically significant increase in mean marginal gap distance after cementation at P-value ≤ 0.05.
Conclusions: Based on the clinical acceptability of 120 μm as a marginal gap, the results of the three all-ceramic superstructures were within the acceptable range for both tested abutments. Marginal gap values increased after cementation of various superstructures on different abutments.