Effect of orthodontic treatment on occlusal condition and masticatory function

Change in occlusion and masticatory function after orthodontic treatment was investigated by a follow-up study in a group of 14 patients with malocclusion (3 men, 11 women, aged 12-46 years). All completed a food questionnaire and underwent occlusal force evaluation using a pressure-sensitive sheet at pre-treatment, post-treatment, and during the retention phase. The number of foods identified as difficult to eat decreased at post-treatment in all patients. The mean occlusal force was 646.6±223.5 N at pretreatment, 401.1±109.1 N at post-treatment, and 530.6±183.6 N during the retention phase. The mean occlusal contact area was 14.1±5.9 mm(2) at pre-treatment, 6.5±1.7 mm(2) at post-treatment, and 9.8±3.8 mm(2) during the retention phase. The mean average occlusal pressure was 47.6±6.6 MPa at pre-treatment, 62.2±5.7 MPa at post-treatment, and 55.4±6.7 MPa during the retention phase. A Dental Prescale film evaluation revealed that occlusal force and occlusal contact area increased over the 1-year retention phase. An improvement in level of satisfaction with mastication ability was reported at post-treatment and during the retention phase. Average occlusal pressure at post-treatment increased significantly (p <0.01), which may account for the observed increase in the ability of the patients to bite through food. These results suggest that an increase in average occlusal pressure improves level of satisfaction with mastication ability.