ABSTRACT
After bimaxillary orthognathic surgery for correction of facial deformity, the factors influencing stability of bone segment are the amount of bone segment, surgical technique, fixation technique, rotation of proximal segment. The aim of this study is to analyze the significance of the factors influencing skeletal relapse after bimaxillary orthognathic surgery. From March 1994 to march 2003, 11 patients who underwent bimaxillary procedures without genioplasty or any other orthognathic surgical procedures were included for sample. Lateral cephalograms were analyzed before surgery, 1 month and 12 months after surgery respectively. Vertical, horizontal, angular and dental measurements were obtained from each tracing using the horizontal and vertical reference lines. The mean amount of bone movement and relapse was 7.03mm, 2.44mm (35%) respectively at pogonion and 3.41mm, 0.6mm (18%) respectively at point A. After statistical analysis of collected data, the amount of skeletal movement, fixation technique were significantly related to relapse, but rotation of proximal segment, surgical procedures were not significantly related to relapse. Then we suggest that when operation is planned, 20-30% overcorrection was recommended at the time of bimaxillary surgery.
Subject(s)
Humans , Congenital Abnormalities , Genioplasty , Orthognathic Surgery , Orthognathic Surgical Procedures , RecurrenceABSTRACT
The purpose of this study is to evaluate the amount of correction and relapse after orthognathic surgery in patients with facial asymmetry and prognathism by means of the frontal cephalogram. Out of twenty prognathism patients who had been diagnosed as having skeletal facial asymmetry in need of orthognathic operation at our institute during last 6 years, only thirteen patients with pre-existing pre-operative(T0), immediate postoperative (T1) and long term follow up(T2) frontal cephalograms were included in the study. The population was divided according to the kind of surgical operation and severity of asymmetry. The midline sagittal reference line (MSR) was drawn and four basic landmarks were marked on the frontal T0, T1 and T2 cephalograms. Radiographic facial asymmetry was found most obviously in the lower jaw(Deviation from MSR: 2.21mm at ANS, 8.34mm at menton). Facial asymmetry was corrected to minimal degree(1.34 at menton) with orthognathic procedures. On long-term follow up, the correction of deviation was maintained as 1.98mm. The relapse rate was 24.1% at menton. The contributing factor was searched and the amount of asymmetry correction and the amount of prognathism correction proved to have statistical significance (p<0.05). In conclusion, asymmetry could be corrected with orthognathic procedures, which could be maintained with minimal degree of relapse. However, in preoperative planning, the degree of relapse should be considered to maximize the aesthetic outcome.
Subject(s)
Humans , Facial Asymmetry , Follow-Up Studies , Orthognathic Surgery , Prognathism , RecurrenceABSTRACT
Sagittal split ramus osteotomy(SSRO) has become one of the most popular procedure for correction of mandibular prognathism. Rigid fixation is favored for its stability and patient comfort. But there were few data presented about skeletal stability and factors contributing to relapse for sagittal split ramus osteotomy with rigid fixation. From August 1997 to August 2002, eleven patients, who underwent sagittal split osteotomy with rigid fixation, were studied. Patients with genioplasty or any other orthognatic surgical procedures were excluded from sample. Lateral cephalograms were analyzed before surgery, 1 month after surgery, and 12 months after surgery. The mean amount of surgical setback was 6.29 mm at pogonion and the mean amount of skeletal relapse was 1.29 mm at pogonion. The mean postoperative horizontal change of soft tissue pogonion was 5.66 mm posteriorly, vertical change of menton was 1.83 mm superiorly, and angular change of ramus inclination was 5.88 degree increased. The mean amount of postoperative movement was 1.9 mm anteriorly at soft tissue pogonion, 2.13 mm superiorly at menton, 0.8 degree was decreases at ramus inclination. The amount of skeletal relapse is related to the amount of setback. The results of this study present that the bilateral sagittal split osteotomy with rigid fixation has many advantages and stable procedure for the correction of mandibular prognathism.
Subject(s)
Humans , Genioplasty , Osteotomy , Osteotomy, Sagittal Split Ramus , Prognathism , RecurrenceABSTRACT
Despite orthodontic treatment(tooth moving) is dynamic act, many orthodontists have used mainly static evaluation method for evaluating effectiveness of the orthodontic appliances. They want to find which is better appliance, especially in the treatment results and treatment period, when they chose one appliance from sugessted appliances for obtaining same treatment goal. The author and colleagues invented and manufactured new machine for getting information about the relative effectiveness from many suggested orthodontic appliances and we named it Calorific machine. We used this Calorific machine to find the relative differences about tooth moving mechanism and tooth moving time between the Burstone's PLA(single force mechanism) and Molar-up's PLA(couple mechanism) for correcting the posterior cross bite. We measured the distance of tooth moving on the occlusal X-ray film and recorded the moving time of the anchored(control elct o-thermal tooth) and lingually tipped lower second molars(experimental electro-thermal tooth) and then processed paired t-est by SAS program The results were as follows. 1. Molar-up's PLA showed more extrusive and horizontal movement than Burstone's PLA at the lingually tipped molar(p=0.0000). 2. There is no finding of tooth movement by Molar-up's PLA at the uprighted molar(p=o.3475) but Burstone's PLA showed a little change(02 mm) at the same molar(p=O.0001). 3. Burstone's PLA took 17.8 minutes for tooth moving but Molar-up's PLA took only 3.8 minutes(p=0.0001)