Abstract Background: The marginal fit of zirconia computer-aided design and computer-aided manufacturing (CAD/CAM) endocrowns (ECs) is critical for restoration success. This digital microscope study was aimed to measure and compare the vertical marginal adaptation (VMA) of CAD-/CAM-made zirconia ECs cemented on maxillary and mandibular molar and premolar teeth with and without the presence of proximal mesial and distal boxes. Materials and Methods: Sixty-four periodontically compromised extracted human teeth were collected and randomly divided into 2 groups, comprising 32 samples on the basis of arch type (maxillary or mandibular) and teeth type (molar or premolar). Further, four subgroups ( n = 8) were made with and without proximal boxes (remaining axial height 3 mm and intrapulpal extension 2 mm). ECs were fabricated from multilayer zirconia using CAD/CAM and cemented according to the manufacturer’s recommendations. Specimens were tested for VMA at the four axial interfaces using a digital stereomicroscope under ×40. The data were analyzed using Mann–Whitney U and Kruskal–Wallis H tests. P ≤ 0.05 was considered statistically significant. Results: All ECs demonstrated VMA within clinically acceptable limits (<120 μm). The highest VMA was recorded at the lingual/palatal surfaces of maxillary premolars (38.5 ± 11.72 μm) and molars (15.9 ± 2.22 μm). Significant differences ( P < 0.001) were observed between arch types, tooth types, and EC surfaces. Conclusion: Zirconia CAD/CAM ECs exhibited acceptable V MA across all evaluated groups. The incorporation of proximal boxes influenced VMA and was marginally higher at the mesial and distal sides with proximal boxes.
Nasser M. Al Ahmari (Tue,) studied this question.