The Effect of Molar Bite Raising on Anterior Overbite.

Purpose: To evaluate first and second molar bite raising effect on anterior incisal overbite using steel bearing balls of predefined dimensions.

Materials and methods: The study involved twenty-three young adults (mean age 25, range 22-34) and was composed of two parts, pre-clinical and clinical. a) Pre-clinical: initial evaluations were conducted on dental casts of the participants mounted on a fully adjustable articulator. Stainless-steel bearing balls (2mm and 3mm diameter respectively) were temporarily positioned in the occlusal central groove of the lower first or second molars. Photographs assessed changes in anterior overbite. b) Clinical: subsequent evaluations used intraoral scans on the same participants, excluding those with molar restorations, before and after applying 2mm-diameter stainless-steel bearing balls on lower first molars. Overbite measurements were performed digitally. Reliability was defined through repeated measurements using intraclass correlation coefficients (ICC).

Results: Pre-clinical measurements showed a 2.8±0.5mm overbite decrease with 2mm-diameter bearing balls on the lower first molars and 3.6±0.5mm on the lower second molars. For 3mm-diameter bearing balls, the decrease was 3.7±0.5mm on the first molars and 4.5±0.5mm on second molars. ICC showed excellent reliability. Clinical intraoral scans revealed a mean overbite decrease of 2.7±0.4mm with 2mm-diameter bearing balls on the lower first molars. No significant difference was found between clinical and pre-clinical results for the same participants.

Conclusions: Larger bite raisers and more posterior placement result in greater overbite reduction. The ratio of bite raising to anterior overbite decrease was 1.6 for 2mm-diameter and 1.4 for 3mm-diameter raisers. Considerable inter-individual variability was noted.