견치유도 형태에 따른 저작근 활성도 비교

Abstract

Lateral incisal guidance angle is the angle between the pathway of mandibulr canine which slides the lingual surface of maxillary canine and horzontal plane. There is a need for resetting standard of this angle in case of artificial changes such as full mouth prosthetic rehabiltation. This study was to analyze the activity of masticatory muscles with lateral incisal guidance angle changes. 17 adults(Male :12, Female :5, mean age: 32.0) with normal class I occlusion, no TMD and missing teeth except for a 3rd molar were selected. Each subject’s maxilla and mandible models were impressed and mounted to semi-adjustable articulator using face-bow transfer. With the working model of upper dentition, a clear acrylic occlusal stabilizing devices were fabricated. The devices were adjusted before the test to be passively fit to the subject’s maxillary dentition. Electrodes were attached on masseter and anterior temoralis muscles to measure electromyograms in the CR position as the noise of the electromyography was supposed to be excluded. And then, in the following situations and lateral movement, activities of those muscles were measured. At test 1, a group function guided lateral movement with canine (type 1), a group function guided lateral movement without canine(type 2) and a canine guided occlusion(type 3) were tested. At test 2,a lateral movement with 15 degree lower lateral incisal guidance angle(type 4), a lateral movement with own lateral incisal guidance angle(type 5) and a lateral movement with 15 degree higher lateral incisal guidance angle(type 6) were tested. The mean lateral incisal guidance angles of right and left were 32.7° and 34.6°, respectively. In terms of the mean muscle activation of temporalis and masseter muscle, there was decreasing tendency in order of type 2, type 1 and type 3 in unique lateral incisal guidance angle at test 1. There was a decreasing tendency of the mean muscle activation of temporalis and masseter muscle in order of type 4, type 5 and type 6 at test 2. The following result was derived from comparing masticatory muscle activation with artificially adjusted lateral incisal guidance angle using reversible occlusal stabilizing device. Muscle activation with canine guidance occlusion was lower than that of group function guidance occlusion and with slightly higher angle than individual unique lateral incisal guidance angle, the muscle activation was the lowest