Chewing performance in orthodontic patients treated with extraction of premolars

Jang, Insan; Jang, Eunhye; Choi, Dong Soon; Cha, Bong Kuen

Abstract

The purpose of the present study was to evaluate the kinematic parameters of the chewing cycles in patients who had undergone comprehensive orthodontic treatment with extraction of premolars and to compare these parameters with those of a non-extraction group. The samples for this retrospective study consisted of kinesiographic recordings obtained from patients who had undergone comprehensive orthodontic treatment without orthognathic surgery. They were divided into a non-extraction group (n=19) and an extraction group (n=40) depending on whether their premolars were extracted for orthodontic treatment. Mandibular kinesiography was recorded using Bio-EGN before (T1) and after (T2) the treatment, and chewing cycle time, velocity, the position of turning point, and the lateral width of the cycle were measured. No significant difference was found in most of the kinematic parameters between the extraction and non-extraction groups at T1 and in those between T1 and T2 in the non-extraction group. In the extraction group, on the other hand, opening and closing velocities significantly decreased and the turning point of the chewing cycle was significantly more superior at T2 than at T1. The chewing cycle time did not significantly differ between T1 and T2 in the extraction group. Patients who have undergone orthodontic treatment with premolar extraction have chewing cycles that are shorter and slower than those before the treatment, and their chewing movement may differ from that of those who have not undergone extraction.