• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.4
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• pp.327-339
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• 1992

This study was undertaken to investigate the effect of orthognathic surgery on occlusal force. The maximum bite force was measured in 26 dentofacial deformity patients, aged 14-26(mean age 20.3) years, before surgery and at IMF removal, 3, 6, and 12months postsurgery. To grope the correlation of bite force and skeletal change after orthognathic surgery, the cephalometric headplates were measured, tabulated and statistically analyzed. The results were as follows. 1. The presurgical maximum bite force was 13.7kg in upper first molar(rt. Side 12.7kg, it. Side 14.6kg). There was remarkable difference with that of normal occlusion. 2. The recovery of bite force was very significant in according to the operation method and the duration of IMF that was 7.6kg at IMF removal, 14.2kg at 3 months, 19.7kg at 6 months. 26.1kg at 12 months postsurgery. 3. To fasten the recovery and to increase the bite force after orthognathic surgery, the long IMF time and the injury to the masticatory muscle should be avoided by the internal rigid fixation and early physical exercise. 4. The bite force was positively correlated to the changes of mandibular plane angle, the angle between platatal plane and mandibular plan, the angle between occlusal plane and mandibular plane, and negatively correlated to the changes of mandibular body length in craniofacial structure. 5. There was no correlationship between bit force and mesial inclination of tooth long axis of first molar in this subject. 6. There was no correlation between the changes of bite force and the changes of mechanical advantage of the temporal and masseter muscle.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.455-474
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• 1993

Degenerative joint disease(DJD) has hun known as one of the diseases which affect the middleor old-aged people. But as orthodontists are getting interested in the adult orthodontics, it is not rare for them to meet the open-bite patients with the TMJ DJD in their clinics. The purpose of this article is to investigate the cephalometric characteristics of the open-bite cases with TMJ DJD. Twelve TMJ DJD patients($15.1\~39.5$ years old) were selected from the patients who visited Department of Orthodontics, Seoul National University Hospital. Cephalograms were taken and means from 60 measurements were compared by t-test with those of the fifty four healthy adults($20.0\~26.7$ years old) who have normal occlusion and TMJ. In this study male and female are compared respectively, for in the normal samples 26 measurements showed significant differences between the male and the female. The results and conclusions axe as follows: 1 In DJD group, ANB and Angle of convexity decreased, which means the retruding of the mandible. The interincisal angle was smaller than that of the normal group. The means of the overbite were -2.1mm in male and -3.0mm in female, and the means of the overjet were 5.6mm in male and 6.7mm in female. The profile was similar to that of Angle's Class II div.1 open-bite. 2. SN-GoMe and FMA increased in DJD but SN-PP and FH-PP did not show any significant difference. In TMJ DJD open-bite cases, the bony structure lower than the palatal plane seemed to play an important role in developing open-bite. 3. In DJD group, PH-ArGo, SArGo and Y-sxis angle increased significantly, but genial angle showed no significant difference. The means of hか were 50.1mm in male and 40.2mm in female, which were significantly smaller than those of the normal(56.5mm in male, 50.9mm in female). These findings seemed to indicate the posterior rotation of mandible resulted from the shortening of the ramus height. 4. Anterior faical height(AFH), upper anterior facial height(UAFH) and lower anterior facial height (LAEH) of DJD showed no significant increase as compared with those of the noraml group. There was no significant difference in the ratio of upper anterior facial height to lower anterior facial height(UAFH/LAFH). But, lower posterior facial height(LPFH) was significantly smaller than that of the normal group. 5. It was thought that the peculiar profile of the TMJ DJD open-bite was resulted from the posterior rotation of mandible as the ramus became short following the degerative destruction of of the condylar head and neck.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.3
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• pp.293-299
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• 2008

Bite force is created by the force of adjacent teeth accompanied with tension of masticatory muscle. The bite force value is greater in male than in female and ha maximum value at first molar. Masseter muscle is associated with bite force and during muscle contraction the electric signal is expressed in EMG form. The aim of the study is to assess recovery time for masseter muscle activity and according to each part of bite force after open reduction with internal fixation when mandibular angle fracture and subcondyle fracture occurred. And to determine the appropriate period for mandibular fracture patients to have normal masticatory activity. 30 patients with normal bite condition was selected for control group and from April, 2007 to September, 2007, 20 patients who visited our department of oral and maxillofacial surgery of Dankook University, were selected for the study and were diagnosed as mandibular angle fracture and subcondyle fracture. For control group, the bite force for incisors, canine, premolars and molars and activity of the masseter muscle was measured and compared for 1, 2, 3, 4, 6 and 8 weeks. That was divided as fracture side and normal side. Mann-Whitney U test was performed for significant difference and the following result was obtained. 1. The maximum voluntary bite force for incisors, canine, premolars and molars portion were 0.113 kN, 0.182kN, 0.295kN and 0.486kN and the masseter muscle activity was 0.192 volts in the control group. 2. The maximum bite force at fracture side was recovered by 4th weeks for incisors, 6th weeks for canine and premolars and 8th weeks for molars and the masseter muscle activity was recovered by 6th weeks in the experimental group. 2. The maximum bite force at normal side was recovered by 4th weeks for incisors, 6th weeks for canine, premolars and molars and the masseter muscle activity was recovered by 3rd weeks in the experimental group. 3. The method for internal fixation by 2.0mm miniplates at both superior and inferior border had no complications according for twenty patients and had a satisfactory recovery. According to the result, patient with mandibular angle fracture and subcondyle fracture, 8 weeks was required for bite force recovery. Therefore, patients with open reduction and internal fixation under general anesthesis, it can be assumed that 8 weeks was needed after operation in order to have normal bite force and masseter muscle recovery.

• The korean journal of orthodontics
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• v.52 no.3
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• pp.210-219
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• 2022

Objective: The purpose of this study was to examine the effectiveness and mechanism of clear aligner therapy for the correction of anterior open bite in adult nonextraction cases. Methods: Sixty-nine adult patients with anterior open bite were enrolled and classified into Angle's Class I, II, and III groups. Fifty patients presented with skeletal open bite (mandibular plane angle [MPA] ≥ 38°), whereas 19 presented with dental open bite. Fifteen cephalometric landmarks were identified before (T1) and after (T2) treatment. The magnitudes of planned and actual movements of the incisors and molars were calculated. Results: Positive overbite was achieved in 94% patients, with a mean final overbite of 1.1 ± 0.8 mm. The mean change in overbite was 3.3 ± 1.4 mm. With clear aligners alone, 0.36 ± 0.58 mm of maxillary molar intrusion was achieved. Compared with the Class I group, the Class II group showed greater maxillary molar intrusion and MPA reduction. The Class III group showed greater mandibular incisor extrusion with no significant vertical skeletal changes. Conclusions: Clear aligners can be effective in controlling the vertical dimension and correcting mild to moderate anterior open bite in adult nonextraction cases. The treatment mechanism for Class III patients significantly differed from that for Class I and Class II patients. Maxillary incisor extrusion in patients with dental open bite and MPA reduction with mandibular incisor extrusion in patients with skeletal open bite are the most significant contributing factors for open bite closure.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.3
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• pp.229-237
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• 1993

This study was intended to evaluate a post-operative relapse tendency in mandibular prognathism patients with open-bite. 18 patients with or without open-bite have undergone sagittal split ramus osteotomy and were investigated radiologically with cephalogram. The results were as following 1. The preoperative anterior facial height, mandibular plane angle and mandibular gonial angle were larger in open-bite patients than in nonopen-bite patients.(p>0.05) 2. There was significant correlation between surgical change of SNA, mandibular plane length and long-term relapse.(p<0.01). 3. There was relatively stable postoperative anterior facial height in open bite patients. 4. There was no significant correlation between the surgical change of mandibular plane angle, amount of mandibular setback and long-term relapse.(p>0.01) 5. This study showed that horizontal relapse was more significant than vertical relapse.

• The korean journal of orthodontics
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• v.15 no.2
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• pp.249-259
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• 1985

To analyze the skeletal characteristics of the open bite, the faces of normal occlusion and open bite were measured using a cephalogram. The factors which were greatly different from normal occlusion were selected. The effects of these factors on the incisal overbite and correlation on these factors were studied. The following results were obtained: 1. The 13 factors which comprised the characteristics of the open bite were obtained. (Table 5) 2. The cause and amount of the open bite were dependent on the skeletal angulation than skeletal length. 3. For determining the incisal overbite, most highly correlated single factor was the interincisal angle. 4. The correlation on the selected 13 factors which comprised the characteristics of the open bite was obtained. (Table 6) 5. The open bite was due to combination of various factors than due to single factor. (Table 3,4).

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.4
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• pp.188-192
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• 2013

Post-traumatic anterior open bite can occur as a result of broken balance among the masticatory muscles. The superior hyoid muscle group retracts the mandible downward and contributes to the anterior open bite. Denervation of the digastric muscle by injection of botulinum toxin type A (BTX-A) can reduce the power of the digastric muscle and help to resolve the post-traumatic anterior open bite. A patient with a bilateral angle fracture had an anterior open bite even after undergoing three operations under general anesthesia and rubber traction. Although the open bite showed some improvement by the repeated operation, the occlusion was still unstable six weeks after the initial treatment. To eliminate the residual anterior open bite, BTX-A was injected into the anterior belly of the digastric muscle. Following injection of BTX-A, the anterior open bite showed immediate improvement. Complication and relapse were not observed during follow-up. Long-standing post-traumatic open bite could be successfully corrected by injection of BTX-A into the anterior belly of the digastric muscle without complication.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.88-95
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• 1997

This study provides the useful actual data instead of the experience data using in industrial fields. Especially, values of each components of cutting force are effective in the rake angle, setting angle and cutting area. Many researches have been made on the work piece materials, kinds of bite materials, rake angle, nose radius and depth of cut, but a few on the bite setting angle. In order to select optimal cutting speed, it was summarized the following results are achieved; A chieved that an affect of cutting resistance on the setting angle is a little under giving experimental conditions and therefore a worker can be choose the value of it randomly.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.3
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• pp.103-110
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• 1997

This study provides the useful actual data instead of the experience data using in industrial fields. Especially, values of each components of cutting force are effective in the rake angle, setting angle and cutting area. Many researches have been made on the work piece materials, kinds of bite materials, rake angle, nose radius and depth of cut, but a few on the bite setting angle. In order to select optimal cutting speed, it was summarized the following results are achieved; A chieved that an affect of cutting resistance on the setting angle is a little under giving experimental conditions and therefore a worker can be choose the value of it randomly.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.13-21
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• 2004

Recently several techniques have been reported for the treatment of anterior open bite in adults characterized by molar intrusion with skeletal anchorage. In this study, five adult patients who had anterior open bite malocclusion were selected to undergo upper molar intrusion with midpalatal miniscrew to close the open bite. The aim of this study is (1) to validate true intrusion of molars in adults (2) to test the usefullness of midpalatal miniscrews as anchorage for intruding upper molars (3) to evaluate the skeletal and dental changes of open bite closure. The results are as follows. (1) All had true intrusion of the maxillary molars. Mean amount of molar intrusion was 3.4mm(range 1.5-5mm). (2) No movement of midpalatal miniscrew occurred during their use. (3) Open bite closure was achieved for all 5 patients. The mandible closed and B-point rotated anteriorly and upward. The mandibular plane angle and the occlusal plane angle decreased.