Benefits of Pre-restorative Orthodontic treatments on Veneer Preparations

Objective: The benefits of pre-restorative alignment has been well documented. These characteristics are of particular interest in cases where patients with mal-aligned dentition who are seeking prosthetic rehabilitation. The question arises whether complete or partial orthodontic alignment is necessary when managing these cases. The purpose of this investigation was to measure the impact of pre-restorative orthodontic treatment on veneer preparation depth and the amount of orthodontic movement necessary to maximize outcome. Methods: 30 arches class I crowding cases requiring 12 months of orthodontic treatment for complete alignment of the anterior teeth were simulated in ClinCheck. Little's index of irregularity was determined on the 3D models to quantify crowding. Models were created from each case at 0, 6, and 12 month of orthodontic treatment for crowded dentition using set-ups. Diagnostic wax up for six anterior veneers was made for each time point, and silicone preparation guides were fabricated. Four different clinicians then prepared the study models for veneers for each time point. A total of 540 teeth were prepared. All prepared arches were scanned and the amount of tooth reduction was determined by 3D software. Results: There was a significant direct correlation between Little's index of irregularity with the percent of teeth being over prepared. Conclusions: Orthodontic treatment time reduced crowding and amount of variance of labial preparation. Little's index of irregularity is a significant predictor of preparation depth and coefficient of variance in preparation depth.