Effect of Tooth Position on Molar Zirconia Crown Restoration with a Modified Dental Measurement Software

This study employed a modified digital technique to evaluate parameters of molar preparations for monolithic zirconia crown restoration, investigating whether clinical preparations with different tooth positions influence restorative outcomes. A total of 238 prepared posterior abutments were analyzed using an intraoral scanner, with parameters including total occlusal convergence (TOC) angle, margin perimeter, and mean abutment height assessed for statistical analysis. The results revealed that the average TOC angle of each posterior tooth exceeded 6°, with the maximum average observed in the mandibular left second molar (35.96 ± 20.21°) and the minimum in the maxillary right first premolar (10.97 ± 6.84°). Statistically significant differences were found in the TOC angle of homonymous second premolars (p < 0.05), where the mandibular left second molar was significantly larger than the other homonymous teeth. Additionally, significant differences existed between teeth in the same quadrant with different positions (p < 0.05), showing a linear increase in TOC angle as the tooth position moved backward. A positive correlation was observed between TOC angle and margin perimeter, while a negative correlation existed between TOC angle and mean abutment height. The findings indicate that clinical zirconia crown preparations often deviate from theoretical TOC recommendations, particularly requiring tailored criteria for mandibular teeth. The developed software integrates digital acquisition with clinical analysis, demonstrating its relevance in prosthodontic practice and education.