Xerox copy of the dental cast for analysis of the stability of mandibular osteotomy

• Published in: Journal of cranio-maxillo-facial surgery Vol. 16; no. 2; pp. 69 - 75
• Main Authors: Ueda, Ken, Kobayashi, Tadaharu, Nakajima, Tamio, Sasakura, Hitoshi, Hanada, Kohji
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.02.1988; Elsevier
• Subjects: Biological and medical sciences; Cephalometry; Copying Processes; Dental Arch - anatomy & histology; Dental Models; Dentistry; Facial bones, jaws, teeth, parodontium: diseases, semeiology; Forecasting; Humans; Mandible - anatomy & histology; Mandible - surgery; Mandibular prognathism; Medical sciences; Movement in the horizontal plane; Non tumoral diseases; Osteotomy - methods; Otorhinolaryngology. Stomatology; Postoperative stability; Prognathism - pathology; Prognathism - surgery; Recurrence; Xerox copy of dental cast; Movement in the horizontal plane; Mandibular prognathism; Xerox copy of dental cast; Postoperative stability; Human; Stability; Malformation; Osteotomy; Stomatology; Surgery; Inferior maxillary; Prognathism
• ISSN: 1010-5182; 1878-4119
• DOI: 10.1016/S1010-5182(88)80021-0

Stability of the mandible was analysed with a Xerox copy of the dental cast in 35 cases of mandibular prognathism corrected by ramus osteotomies. The occlusal relationship in the Xerox copy was illustrated by superimposing two contact points on the upper and lower dental arches and the change in the position of the lower dental arch in relation to the upper dental arch was obtained by superimposing the latter on preoperative predicted postoperative, and six months postoperative occlusions. The stability of the mandible was analysed by measuring the movement of five landmarks (two posterior, two molar and one incisor points) set around the lower dental arch to represent the movement of the mandible. The relapse was estimated by the movements of the landmarks from the predicted postoperative occlusion to the six months postoperative occlusion. The mean estimated anterior relapses at the posterior and molar points with the larger predicted movement and the incisor point were between 0.9 mm. and 2.0 mm. at six months postoperatively, whereas on the side with the smaller predicted movement, the points moved posteriorly by 0.6 mm. and 0.5 mm. Despite the fact that the amount of the predicted lateral movement was much smaller than that of the predicted posterior movement at operation, the posterior points were estimated to relapse laterally by 2.0 mm. and 1.7 mm. Thus, although there were significant correlations between the predicted movement at operation and estimated relapse at six months at all landmarks except for the anteroposterior movement at the incisor point, the highest correlation with correlation coefficients of more than 0.86 was seen in the lateral movement at the posterior points. The large movement at the incisor point was stable unless it was accompanied by large lateral movement at the posterior points. The results indicate the importance of avoiding large lateral movements at the osteotomy site in planning the postoperative occlusion, to minimize relapse in ramus osteotomies.