• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권3호
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• pp.370-375
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• 2008

Sagittal split ramus osteotomy (SSRO) is widely used in treatment of dentofacial deformities. But, many complications can occur including unfavorable fractures during osteotomy. To prevent these complications, it is necessary to understand comprehensively the anatomy of the mandiular ramus. The purpose of this study was to evaluate the morphology of the madibular ramus in manibular prognathism patients by computed tomography comparing with normal control group. The study group consisted of 33 skeletal class III patients (20 males, 13 females) and the control group consisted of the 52 patients without dentofacial deformities (32 males, 20 females). The mean age of study group was 22.0-year old, and that of control group was 37.1-year. For the CT examination, following scan parameters was used: 1mm slice thickness, 0.5 second scan time, 120kV and 100mA/s. The axial scans of the head were made parallel to the mandibular occlusal plane. The anteroposterior length of the ramus, the distance from anterior border of the ramus to lingula, the relative distance from the anterior border of the ramus to lingula compared to the anteroposterior length of the ramus, the thickness of anterior and posterior cortical plate, the thickness of medial cortical plate of the ramus at lingula level, the thickness of cancellous bone of the ramus at lingula level were measured. The skeletal class III mandibular prognathism patients exhibited shorter anteroposterior length of the ramus, thicker anterior and posterior cortical plate, thinner mediolateral cancellous bone thickness. The lingula has a relative stable anteroposterior position in ramus in all groups. There was higher possibility of fusion of medial and lateral cortical plate at lingula level in the mandibular prognathism group. In conclusion, the mandibular prognathism patients have narrow rami with scanty cancellous bone, which means that careful preoperative examination including CT scan can prevent undesirable fractures during osteotomy.

• 대한치과의사협회지
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• 제37권3호통권358호
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• pp.170-173
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• 1999

• 대한치과의사협회지
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• 제37권4호통권359호
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• pp.239-241
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• 1999

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권5호
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• pp.265-271
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• 2003

Skeletal relapse is known as a complication following orthognathic surgery of mandibular prognathism and occurring during intermaxillary fixation period. Therefore relapse of teeth and skeleton during intermaxillary fixation period is considered as a important problem of orthognathic surgery. In this study, cephalolateral radiographs taken at pre-operation, immediate post-operation and after release of intermaxillary fixation were measured for evaluation of dental and skeletal relapse in 30 cases. The cases were classified as screw fixation group and plate fixation group, then we compared magnitude of dental and skeletal changes of each group. The results were as follows 1. The $\underline{1}$ SN angle increased at immediate post-operation with a mean value of $0.12^{\circ}$ and at intermaxillary fixation period with a mean value of $0.43^{\circ}$ (p>0.05). 2. The $\overline{1}$ MP angle decreased with a mean value of $0.14^{\circ} at immediate post-operation and with a mean value of $1.28^{\circ} during intermaxillary fixation period but there were not significant difference(p>0.05). 3. There were not significant difference in magnitude of dental position changes between screw fixation group and plate fixation group(p>0.05). 4. Gonial angle increased with a mean value of $0.62^{\circ} during intermaxillary fixation period. Each group showed changes of gonial angle during intermaxillary fixation period but there were not significant difference(p>0.05).

• Imaging Science in Dentistry
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• 제54권2호
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• pp.181-190
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• 2024

Purpose: This study compared sequential changes in skeletal stability and the pharyngeal airway following mandibular setback surgery involving fixation with either a titanium or a bioabsorbable plate and screws. Materials and Methods: Twenty-eight patients with mandibular prognathism undergoing bilateral sagittal split osteotomy by titanium or bioabsorbable fixation were randomly selected in this study. Lateral cephalometric analysis was conducted preoperatively and at 1 week, 3-6 months, and 1 year postoperatively. Mandibular stability was assessed by examining horizontal (BX), vertical (BY), and angular measurements including the sella-nasion to point B angle and the mandibular plane angle (MPA). Pharyngeal airway changes were evaluated by analyzing the nasopharynx, uvula-pharynx, tongue-pharynx, and epiglottis-pharynx (EOP) distances. Mandibular and pharyngeal airway changes were examined sequentially. To evaluate postoperative changes within groups, the Wilcoxon signed-rank test was employed, while the Mann-Whitney U test was used for between-group comparisons. Immediate postoperative changes in the airway were correlated to surgical movements using the Spearman rank test. Results: Significant changes in the MPA were observed in both the titanium and bioabsorbable groups at 3-6 months post-surgery, with significance persisting in the bioabsorbable group at 1 year postoperatively (2.29°±2.28°; P<0.05). The bioabsorbable group also exhibited significant EOP changes (-1.21±1.54 mm; P<0.05) at 3-6 months, which gradually returned to non-significant levels by 1 year postoperatively. Conclusion: Osteofixation using bioabsorbable plates and screws is comparable to that achieved with titanium in long-term skeletal stability and maintaining pharyngeal airway dimensions. However, a tendency for relapse exists, especially regarding the MPA.

• 대한치과교정학회지
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• 제50권1호
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• pp.52-62
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• 2020

This case report presents the orthodontic treatment of a 25-year-old patient with skeletal Class II and severe maxillary arch crowding, moderate mandibular arch crowding, anterior crossbite, and a missing lower incisor. He was treated with molar distalization using a modified C-palatal plate and temporary anchorage devices to create sufficient space for retraction. The total treatment duration was 21 months. After treatment, his occlusion and smile esthetics showed significant improvement. The modified C-palatal plate represents a treatment modality that enhances the prospects of non-extraction treatment and reduces the need for extraction.

• 대한치과교정학회지
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• 제52권5호
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• pp.362-371
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• 2022

Orthognathic surgery is the primary treatment option for severe skeletal discrepancy. However, orthodontic camouflage should be considered as an alternative treatment option, considering the risks of surgery. A 19.5-yearold man presented with a severe prognathic mandible with a Class III molar relationship and an anterior crossbite. Orthognathic surgery could be considered because of his severe skeletal discrepancy and mandibular prognathism. However, the anesthetist for orthognathic surgery did not recommend surgery under general anesthesia because of risk factors associated with the patient's aplastic anemia, including bleeding and infections. Thus, a camouflage treatment to promote backward rotation of the mandible via orthodontic extrusion of the posterior teeth was planned. An anterior bite plate, intermaxillary elastics, and fixed orthodontic appliances were used to extrude the posterior teeth and to align the dentition. After 17 months of nonsurgical orthodontic treatment, normal occlusion was achieved, and the facial profile was dramatically improved. This case report describes the dentoskeletal and soft-tissue effects of mandibular rotation and its long-term stability.

• Archives of Reconstructive Microsurgery
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• 제24권2호
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• pp.68-74
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• 2015

Purpose: The reconstruction of femur and tibia defects following tumor resection remains a surgical challenge. The clinical outcome of free vascularized fibula graft (VFG) reconstruction with locking plate for massive femur and tibia defects of more than 10 cm that were secondary to skeletal tumor resection is reported. Materials and Methods: Thirteen patients with a mean follow-up of 3.3 years were reviewed. Seven patients received vascularized fibula grafts in the femur and six in the tibia. The mean bony defect of the femur and tibia was more than 10 cm and the length of the grafted fibula was more than 15 cm. All defects were stabilized with long locking plates. Results: All patients were free of disease at final follow-up; All VFGs were transferred successfully. All patients had a successful outcome with bony union. Stress fractures of the grafted fibula had occurred but the locking plate stabilized the fracture and healed until the last follow-up. All patients were able to walk without a brace after a mean of 9 months postoperatively. Conclusion: VFG with locking plate is a reliable reconstructive procedure for massive femur and tibia defects.

• KCI Concrete Journal
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• 제12권2호
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• pp.55-72
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• 2000

This paper proposes a mechanical model to describe the load-deformation responses of the reinforced concrete plate members under service load state. An Analytical method is introduced on the basis of the rotating crack model which considers equilibrium, compatibility conditions, load-strain relationship of cracked member, and constitutive law for materials. The tension stiffening effect in reinforced concrete structures is taken into account by the average tensile stress-strain relationship from the load-strain relationship for the cracked member and the constitutive law for material. The strain compatibility is used to find out the crack direction because the crack direction is an unknown variable in the equilibrium and compatibility conditions. The proposed theory is verified by the numerous experimental data such as the crack direction, moment-steel strain relationship, moment-crack width relationship. The present paper can provide some basis for the provision of the definition of serviceability for plate structures of which reinforcements are deviated from the principal stresses, because the present code defines the serviceability by the deflection, crack control, vibration and fatigue basically for the skeletal members. The proposed theory is applicable to predict the service load state behavior of a variety of reinforced concrete plate structures such as skew slab bridges, the deck of skew girder bridges.

• Journal of Species Research
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• 제5권3호
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• pp.483-497
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• 2016

Nine new species of genus Ircinia (Demospongiae: Dictyoceratida: Irciniidae) from Jejudo Island, Korea are described. All of the new species are distinguished from the others reported species of Ircinia by the skeletal structure, especially massive fasciculate primary fibres. The characters of genus Ircinia have primary fibres cored with foreign debris and no cored secondary fibres. Primary fibres are not easy to distinguish from secondary fibres if they are not cored. Secondary web has perforated plate or meshed net. All new species have loosely arranged skeletal fibres network.