• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.1
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• pp.48-54
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• 2005

This is to evaluate the postoperative cephalometric changes of the chin advanced by the genioplasty. Thirty-eight patients who underwent advancement genioplasties at Ewha Womans University Mokdong Hospital between January of 2001 and February of 2003. They were followed up for at least 12 months with lateral cephalographs. The remodelling changes of the horizontal linear measurement between the Pogonion and Perpendicular line to FH plane were measured and analysed by Independent sample tests. The chin advancement resulted in $1.3{\pm}0.3mm$ resorption (28.2% of advancement) after 6 months, but in $1.4{\pm}0.2mm$ after 1 year. If the chin was advanced less than 3 mm, remodelling followed by $1.2{\pm}0.2mm$ reduction, but $1.3{\pm}0.3mm$ reduction followed after chin advanced over 4 mm. There were no significant differences in the amount of bone resorption by the gender, number of genial cut-steps and acompanied osteotomies.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.2
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• pp.206-216
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• 2000

Predictional study for lateral change between pre- and post-orthognathic surgery has been emphasized mainly on anterior area of lateral profile; upper lip, lower lip and chin et al. So interest for lateral profile change has been less in posterior area of lateral profile and literature analyzing gonial angle change is rare. The purpose of this study is to make prediction for gonial angle change possible and to offer somewhat treatment guidance for gonial angle to be improved by investigating overall gonial angle change between pre- and post-orthognathic surgery and inquiring into factors influencing on pattern of genial angle change. For this study 35 patients were selected retrospectively. Lateral cephalometric radiographs were taken in just pre-op time, pod 1 day, pod 1 year. They were analyzed and genial angles were measured. The results were as follows : 1. Gonial angle at pod 1 day was decreased about $9.3^{\circ}$ than pre-op and gonial angle at pod 1 year was increased about $4.0^{\circ}$ than pod 1 day. So genial angle at pod 1 year was decreased about $5.3^{\circ}$ than pre-op genial angle(p<0.01). 2. Mean pre-op gonial angle was $129.4^{\circ}$, showing significantly high value than normal and mean gonial angle at pod 1 year was $124.1^{\circ}$, showing value near to normal. 3. Mean gonial angle change between pre-op and pod 1 year was decreased about $5.4^{\circ}$ in female and $5.3^{\circ}$ in male. There was no statistically significant difference between male and female(p>0.05). 4. Principal factor influencing on decreased gonial angle in gonial angle change between pre-op and pod 1 year was amount of mandibular setback. 5. Principal factor influencing on increased gonial angle in gonial angle change between pod 1 day and pod 1 year was % horizontal relapse, and it was thought that resorption and bone remodelling on posterior area in mandibular distal segment also were related to increased gonial angle. 6. It is thought that sagittal split ramus osteotomy in mandibular prognathic patients with high value of gonial angle is effective to improvement of gonial angle, and In patients who have normal range of gonial angle and are required with excessive mandibular setback, short lingual cut method, additional resection of posterior margin of distal segment, Obwegeser II method will be considerd. 7. More prudent operation and careful post-op management will be responsible for maintenance of postoperative stable gonial angle.