Bite Force Level, Contact Point Tightness and Lower Anterior Crowding

Objectives: The purpose of this study was to define the change in the anterior component of force (ACF) when heavy vs. light bite forces are applied, and to examine whether non-contact at contact point (CP) CP3-2 or CP4-3 reduces the amount of lower anterior crowding (LAC). Methods: The tightness of dental contact point (TDCP) was measured on 30 young women (mean age 25 ± 4.3) at CP6-5, CP5-4, CP4-3, CP3-2, and CP2-1 using a TDCP device without occlusal load, and while biting on a bite force device at 50% and 25% of the maximum bite force (MBF) at the first molar, first premolar and canine. For each CP, the ACF was calculated by subtracting the TDCP value without occlusal load from the TDCP value with load. LAC was measured on 124 young women (mean age 23.47 ± 4.7) with a caliper and spaced/normal/tight CP was measured with a metal strip (0.03 mm) at CP3-2 or CP4-3. Results: Significant differences in the ACF (p<0.001) were found when high vs. low bite forces were applied. Non-CP at CP3-2 and CP4-3 similarly reduced LAC, but crowded and normal CP4-3 contributed more to LAC than CP3-2. Conclusions: Normal chewing (below MBF) is a physiologic mechanism that prevents LAC. The canine plays an important role in the dissipation of the ACF. Spaces in the lower arch between the canine and lateral incisor negate LAC, thus presenting another physiologic protective mechanism for lower anterior alignment. An unnatural anterior bite pattern, i.e., in the premolar instead of molar region, bear the risk of LAC.