• Archives of Craniofacial Surgery
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• v.21 no.6
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• pp.384-386
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• 2020

This report describes osteotomy and iliac bone graft for malunion caused by failed mandibular fracture reduction. A 27-year-old man was referred 3 months after a motor vehicle accident. At another hospital, two operations had been performed for symphyseal fracture using two resorbable plates. Malocclusion was noted, and panoramic radiography and computed tomography revealed a misaligned dental arch, with a 9.37-mm gap between the central and the lateral incisor of the left mandible. A wafer was made from the patient's dental model, and a maxillary arch bar was applied. Through a lower gingivolabial incision, osteotomy was performed between the malunited symphyseal fracture segments. Both segments were reduced to their original position using the wafer and fixed with titanium miniplates via intermaxillary fixation (IMF). The intersegmental gap was filled with cancellous bone from the iliac crest. The gingival defect was covered with a mucosal transposition flap from the gingivolabial sulcus. IMF and the wafer were maintained for 5 and 9 weeks, respectively. At postoperative week 13, the screws were removed from the mandible and satisfactory occlusion was noted. His mouth opening improved from 2.5 to 3 finger breadths (40 mm). This case demonstrates the need for sufficient IMF when using resorbable plates.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.4
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• pp.308-315
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• 2023

In the case of a patients who have lost the centric stop and have a staggered occlusion of the residual teeth, various movements occur when the denture is loaded. Implant placement is necessary to reinforce the retention, support, and stabilization elements to reduce denture movement. However, in this case, considering the patient's age, aversion to surgery, and bone loss, implants were not placed and restoration was performed with a removable partial denture. In this case, it is important to set the correct mandibular position for restoration because the patient has a habit of chewing with the remaining teeth. In this case, a stable mandibular position was established using a gothic arch tracing, and good results were obtained by restoring with partial dentures, so this is reported.

• Journal of the korean academy of Pediatric Dentistry
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• v.7 no.1
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• pp.53-61
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• 1980

The purpose of this study was to statistically evaluate the spacing of primary dentition according to whether or not a space existed and measurement of amount of space in 205 children (male 114, female 91) from 2 to 6 years of age. The results were as follows; 1. In the incidence of interdental space on each region, spacing between the primary lateral incisors and primary canine in maxilla and between the primary canine and 1st primary molar in mandible showed the highest percentage, on the other hand, spacing between the 1st and 2nd primary molars in both jaw showed the lowest percentage. 2. In the kinds of interdental space, the state of primate space and other space together showed the highest percentage, and in the degree of spacing, $S_2$ showed the highest percentage in both jaw. 3. In the incidence of primate space, maxillary primate space showed higher percentage than mandibular primate space in bilateral case. 4. In the type of arch form, spaced arch showed higher percentage than closed arch and about the half of closed arch showed crowding. 5. In both Jaw, available space showed incisor segments, canine segments, and premolar segments in order of amount, and there were not statistically significant differences of sex or jaws in the amount of available space.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.3
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• pp.507-512
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• 1999

In the mixed dentition, many children have mild crowding of anterior dentition on the mandibular arch and mesial tilting of mandibular molar. Lip bumper have been used to gain arch length for the alignment of mild to moderate crowded dental arches. As such, they may provide an alternative to extraction therapy. The claimed therapeutic effect of the lip bumper is bodily forward incisor movement, flaring of the lower incisors, and distal tipping of the molar. The dental changes can be attributed to removal of lip pressure on the lower anterior dentition and the distal forces exerted at the molar abutment. The purpose of this study is to show more easily method of treatment for mild anterior crowding of mandible.

• The korean journal of orthodontics
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• v.50 no.2
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• pp.120-128
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• 2020

Objective: The aims of the present study were to evaluate the changes in the maximum lip-closing force (MLF) after orthodontic treatment with or without premolar extractions and verify the correlation of these changes with dentoskeletal changes. Methods: In total, 17 women who underwent nonextraction orthodontic treatment and 15 women who underwent orthodontic treatment with extraction of all four first premolars were included in this retrospective study. For all patients, lateral cephalograms and dental models were measured before (T0) and after (T1) treatment. In addition, MLF was measured at both time points using the Lip De Cum LDC-110R^® device. Statistical analyses were performed to evaluate changes in clinical variables and MLF and their correlations. Results: Both groups showed similar skeletal patterns, although the extraction group showed greater proclination of the maxillary and mandibular incisors and lip protrusion compared to the nonextraction group at T0. MLF at T0 was comparable between the two groups. The reduction in the arch width and depth and incisor retroclination from T0 to T1 were more pronounced in the extraction group than in the nonextraction group. MLF in the extraction group significantly increased during the treatment period, and this increase was significantly greater than that in the nonextraction group. The increase in MLF was found to be correlated with the increase in the interincisal angle and decrease in the intermolar width, arch depth, and incisor-mandibular plane angle. Conclusions: This study suggests that MLF increases to a greater extent during extraction orthodontic treatment than during nonextraction orthodontic treatment.

• The korean journal of orthodontics
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• v.12 no.1
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• pp.21-26
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• 1982

This study was undertaken to document relations between facial skeletal pattern and dental occlusion. The data in .this study were collected from pretreatment cephalometric radiographs and study models of patients' records present in the files of Orthodontic Department, Seoul National University Hospital. Patients were selected on the basis of a mandibular plane-sella nasion angle equal to or greater than $38^{\circ}$ (high SN-MP angle) or equal to or less than $26^{\circ}$ (low SN-MP angle). Patients in the mixed dentition and with missing permanent teeth were excluded for ease of assessing tooth size / arch circumference relationships and then 30 high SN-MP and 11 low SN-MP patients were selected among them. The mean age of these two groups of patients was high SN-MP, $12.8{\pm}1.23$ years and low SN-MP, $13.0{\pm}1.48$ years. The following conclusions were obtained. 1. In the maxilla and mandible the mean tooth size of high SN-MP patients was nearlly identical to the low SN-MP patients. 2. The mean maxillary arch circumference was increased in low SN-MP group compared with high SN-MP group and a smilar, but smaller, mean increase was present in mandible. 3. The difference between the mean maxillary circumference required and the mean maillary circumference present ranged from -4.8mm in the high SN-MP group to -1.3mm in the low SN-MP group. A small range of means occurred in the mandible (high SN-MP: -4.0mm to low SN-MP: -1.8mm). 4. In the maxilla and mandible the mean arch length was nearly identical in the high and low SN-MP groups. 5. The mean incisor inclination was increased as the SN-MP angle decreased in the maxilla and mandible. 6. The men distance of the maxillary first molar from anterior border of the pterygomaxillary fissure was nearly similar between high and low groups. 7. The mean mandibular intermolar width was increased from high SN-MP to low SN-MP patients.

• The korean journal of orthodontics
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• v.47 no.1
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• pp.39-49
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• 2017

Objective: This retrospective, cross-sectional study aimed to establish reference data for normal crown and root lengths and the root-crown ratios (R/C ratios) for the mature maxillary and mandibular incisors in a Korean population by using cone-beam computed tomography (CBCT). Methods: We included 672 Korean patients (141 men and 531 women; mean age, $27.2{\pm}7.7years$) who underwent CBCT examinations during various dental treatments. Crown and root lengths and the R/C ratios of the maxillary and mandibular incisors were measured using CBCT data, which were analyzed to detect significant differences between demographic factors as well as sagittal and vertical skeletal or occlusal relationships. Results: Teeth of the same type in each half-arch were symmetrical. The mean R/C ratios varied from 1.1 to 1.2 for the maxillary incisors and from 1.3 to 1.4 for the mandibular incisors. Crown and root lengths were greater in men than in women, regardless of tooth type. Root lengths and R/C ratios for the mandibular incisors were significantly greater in patients with skeletal Class II malocclusion or an excessive overjet than in the other patients. The R/C ratios for the mandibular incisors were lower in patients with an open bite than in those with a normal or deep bite. Moreover, the R/C ratios for the mandibular incisors increased with age. Conclusions: The data obtained in our study can serve as reference values for crown and root lengths and the R/C ratios for the maxillary and mandibular incisors in the Korean population.

• The Journal of Advanced Prosthodontics
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• v.14 no.1
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• pp.32-44
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• 2022

PURPOSE. Mandibular flexure is a crucial phenomenon that may affect the success of rigid bilateral mandibular prosthetic treatment. The aim of this study was to determine the amount of median mandibular flexure (MMF) that occurs during mouth opening from anterior to posterior mandible in seven different regions, in different age and gender groups of both dentulous and edentulous subjects, using an intraoral digital scanner. MATERIALS AND METHODS. In this study, the mandibular arch of 56 dentulous and 35 edentulous individuals were scanned with an intraoral scanner at both the minimum mouth opening (MnMO) and the maximum mouth opening (MxMO). MMF values were calculated by subtracting the distance value at the MxMO from the distance between the reference points at the MnMO at seven different mandibular regions of dentulous and edentulous subjects. In addition, the left and right side MMF values were measured. All data were analyzed statistically (α = .05). RESULTS. MMF value increased linearly from anterior to posterior mandible in both dentulous and edentulous individuals. The differences in MMF values were not statistically significant according to side (left/right), age, or gender (P > .05). No significant differences were found between the mean MMF values of the same region in both dentulous and edentulous individuals (P > .05). CONCLUSION. MMF was seen in different regions of the mandibles of both edentulous and dentulous individuals measured at the MxMO. Mandibular flexure should be considered for the success and prognosis of the long-span and rigid prostheses.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.17 no.2
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• pp.171-179
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• 1995

The conservative treatment of the condylar fracture has been used for a long time because of its simplicity, good prognosis and less complication. Traditionally the conservative treatment has been carried out by maxillomandibular fixation using arch bar and wire. But a simplified technique of maxillomandibular fixation introduced here is a procedure that 4 bone screws are placed above the apecies of the maxillary and mandibular canines and then ipsilaterally placed maxillary and mandibular bone screws are linked by a loop of wire each other. This procedure has several advantages compared with the traditional maxillomandibular fixation method. 1) it provides simplicity for the operators. 2) it sustains maxillomandibular fixation more rigidly compared with arch bar technique. 3) it keeps stable maxillomandibular fixation in the region of the anterior teeth so that anterior open bite tendency can be remarkably minimized. 4) it does not injure the periodontal tissue because the teeth are not engaged and causes less discomfort to the patient. 5) it decreases the possibility of operator's AIDS infection through inadvertent skin puncture. 6) it is highly recommended for the patients whose teeth are available for maxillomandibular fixation. The two male patients were diagnosed as bilateral condylar and symphyseal fracture of the mandible. They restored stable occlusion and functional mandibular movement only by a simplified technique of maxillomandibular fixation.

• The korean journal of orthodontics
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• v.19 no.2
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• pp.130-143
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• 1989

The purpose of this study was to assess the early effect of FR III on the growing patients with anterior cross-bite. The lateral cephalograms and models were obtained from 7 patients at the time of pretreatment and correction of anterior cross-bite. The results were as follows: 1. A slight tendency of rotation toward anterosuperior direction and the growth to anterior direction were shown in maxilla. 2. There were a little change of mandibular vertical position and increase in lower facial height although some variations existed. 3. The bodily or labial tipping movement was shown in maxillary incisors. 4. The lingual tipping of mandibular incisors was shown in all cases. 5. Maxillary arch width increased while mandibular arch width usually changed a little although some variations existed. But it was difficult to summary in a word because variable responses were noted according to a wide variety of skeletal type, growth, and malocclusion.