• Journal of Technologic Dentistry
• /
• v.38 no.2
• /
• pp.57-62
• /
• 2016

Purpose: The purpose of this study was to assess precision of crown prostheses that were fabricated by using 2 kinds of bur or 3 kinds of bur. Methods: The crowns were fabricated by using the first molar of the right maxillary in this study. The abutments that were prepared were scanned by using a scanner and designed by using CAD software. Based on the crown design, NC data were created with CAM software. The created NC data were used while fabricating the crown prostheses by using 5-axis milling machine. Scanning was done for the internal and external surface of the completed crown prostheses and 3-dimensional measurement was conducted for precision assessment. Results: The $RMS{\pm}SD$ value for the external surface of the crown prostheses that was fabricated by using two burs and three burs were $28.5{\pm}4.1{\mu}m$ and $19.1{\pm}2.8{\mu}m$, respectively; and the value for two burs were bigger than that for three burs with statistical significance (p<0.001). The $RMS{\pm}SD$ value for the internal surface of the crown prostheses that was fabricated by using two burs and three burs were $14.9{\pm}1.9{\mu}m$ and $13.3{\pm}2.5{\mu}m$, respectively; and the value for two burs were bigger than that for three burs but with no statistical significance. Conclusion: Based on this study, the prostheses that were fabricated by using 3 bur presented better stability compared to those that were fabricated by using 2 bur and statistically significant difference was found only in the external surface.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.34 no.6
• /
• pp.404-412
• /
• 2012

Purpose: The purpose of this study was to evaluate postsurgical facial hard tissue stability after orthognathic surgery with/without posterior impaction in skeletal class III malocclusion patients, and to evaluate the horizontal relapse tendency, according to changes in anteroposterior discrepancy and occlusal planes. Methods: Ninety patients, who had undergone orthognathic surgery in Pusan National University Dental Hospital, were enrolled in this study. Three main groups were classified as follows: Thirty patients underwent mandibular setback bilateral sagittal split ramus osteotomy (BSSRO) only (BSSRO group, BG); another thirty patients underwent mandibular setback BSSRO and Le Fort I osteotomy with posterior impaction (posterior impaction group, PG); and another thirty patients underwent mandibular setback BSSRO and Le Fort I osteotomy without posterior impaction (non-posterior impaction group, NPG). Preoperative (T0), immediate postoperative (T1) and six-month follow-up period (T2) lateral cephalograms were taken, and various parameters were measured. The analyses were done by linear and angular measurements between T0-T1 and T1-T2, to evaluate postsurgical facial hard tissue stability. Results: Mean horizontal relapse rates were distributed from 11.81% to 19.08%, and there were significant postsurgical changes (0.52 mm~2.44 mm) at the B point in all 3 groups. But, there were no statistical differences on relapse rate among BG, PG and NPG patients. Conclusion: In this study, the postsurgical stabilities of BSSRO and Le Fort I osteotomy with/without posterior impaction in skeletal class III malocclusion patients were acceptable. There were no significant statistical differences in mandibular stability according to changes in anteroposterior discrepancy and occlusal planes.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.29 no.6
• /
• pp.485-493
• /
• 2007

Introduction: Although several types of calcium-phosphate coumpound have been frequently applied to osseous defects at maxillofacial area for many years, there is a controversy about its efficiency on bone conductivity comprared to xenograft bone substitute. Alloplastic carbonapatite has been introduced to improve disadvantages of hydroxyapatite and to mimic natural bone containing carbon elements. However, a preclinical study about its efficiency of osteoconductivity has not been reported. This study was performed to evaluate the early osteoconductive potential of synthetic carbonapatite with multiple pores relative to anorganic bovine xenograft. Materials and methods: Total 5 beagle dogs were used for maxillary augmentation model. The control (anorganic bovine xenograft) and experimental groups (synthetic carbonapatite) were randomly distributed in the mouth split design. After bone graft, all animals were sacrificed 4 weeks after surgery. Histological specimens with Masson Trichrome staining were made and histomorphometrically analysed with image analyser. The statistical analysis was performed using paired t-test. Results: In both groups, all animals had no complications. The experimental group showed relatively much new bone formation around and along the bone substitutes, whereas it was clearly reduced in the control group. The ratios of new bone area to total area, to material area and to the residual area excluding materials were higher in the experimental group ($0.13{\pm}0.03,\;0.40{\pm}0.13,\;0.20{\pm}0.06$ respectively) than in the control group ($0.01{\pm}0.01,\;0.03{\pm}0.02,\;0.03{\pm}0.03$, respectively). And the differences between both groups were statistically significant (p<0.001, <0.01, <0.01, respectively), while the ratio of material area to total area in two groups was not significant. Conclusion: Carbonapatite showed a high osteoconductivity in the early stage of bone healing compared to bovine derived anorganic bone substitute. This study suggests that this bone materials can be applied as a reliable bone substitute in the clinical treatment.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.29 no.6
• /
• pp.509-512
• /
• 2007

Purpose: The Le Fort I osteotomy is a commonly performed maxillary procedure for dentofacial deformity. One of the risks of this procedure is major hemorrhage resulting from injury to the descending palatine artery. So it is very important to know the exact position of the descending platine artery. An increased understanding of the position of this artery can minimize the intra-operative bleeding while allowing extension of the bone cuts to achieve exact positioning maxilla. The aim of this investigation was to study the position of the descending palatine artery as it relates to the Le Fort I osteotomy. Methods and patients: Total 40 patients who underwent Le Fort I osteotomy in SNUDH OMFS were studied in this study. We measured the distance from the pyriform aperture to the descending palatine artery (DPA distance) using a ruler. We investigated the relationship between DPA distance, the distance from A point to the McNamara line on lateral cephalography and the patient's body height. Results: The average distances from the pyriform rim to the descending palatine artery were 35.3 mm on the right (range: $30{\sim}40mm$) and 33.7mm (range: $30{\sim}41mm$) on the left in males. Those in females were 33.4 mm on the right (range: $28{\sim}40mm)$ and 32.8mm (range: $27{\sim}38mm$) on the left. The significances between the distance the DPA distance, the body height and the distance from A point to McNamara line were not found. Conclusion: Injury to the descending palatine artery during Le Fort I osteotomy can be minimized by not extending the osteotomy more than 30 mm posterior to the pyriform aperture in mal, and 27 mm in female.

• Journal of Korean Academy of Nursing
• /
• v.26 no.3
• /
• pp.688-696
• /
• 1996

The purpose of this study was to investigate the fluid balance of the patients who were either on soft fluid diet or total parenteral nutrition. We studied 19 patients with neurologic disorders and 22 patients with oromaxillary surgery who were admitted to either D university hospital in Choognam or S general hospital in Seoul between May and November 1995. The mean age for the patients who had oromaxillary surgery was 24 years and their average hospital stay was 9 days. The mean age of the patients with neurologic disorders was 54 years and they were bedridden for average of 71 days. For the maxillary bone surgery patients we did not limit the range of their activities in the ward during data collection period. The patients with neurological disorders were bedridden and did not move around the ward. They were all either on soft fluid diet, or total parenteral nutrition. The findings of this study are as follows ; 1) The difference of the triceps skinfold thickness between the baseline and the final measurement was 0.4cm for neurologic patient group and 0.5cm for oromaxillary surgery patient group. The difference was not statistically significant in each group. 2) In the oromaxillary surgery patient group, the daily intake of fluid in the form of pure water, other beverages, fluid diet as well as IV fluid was 4581m1 while urine output was 2979ml. The difference between fluid intake and output was statistically significant, indicating that fluid intake was far more than urine output. In neurologic patient group, the daily intake of fluid including water from fluid diet and IV fluid was 2701m1 whereas urine output was 2253m1 and they were statistically significant. 3) For a more accurate assessment we adjusted the fluid balance based on weight changes during data collection period. In the oromaxillary surgery patient group. the difference between fluid intake and output was 1238m1 after weight changes being adjusted. The difference was statistically significant, suggesting fluid overload in this patient group. In neurologic patient group, the difference between fluid intake and output considering weight changes was 124ml. The difference was not statistically significant, suggesting that the fluid intake and output was well balanced in this patient group.

• The korean journal of orthodontics
• /
• v.15 no.1
• /
• pp.123-140
• /
• 1985

Variation in the facial pattern and effect of the rotational jaw growth on the facial proportion were studied in serial cephalometric radiographs of 40 Korean children (25 boys, 15 girls) ranging in age from 6 to 13 years. According to Y-axis (N-S-Gn) growth change during the 7 years of period, the subject who had exhibited 'wave-like' manner of Y-axis growth change within ${\pm}\;2^{\circ}$ was classified to the Parallelwise group and the subject who had exhibited Y-axis increase more than $+2^{\circ}$ was classified to the Clockwise rotation group and the subject who had exhibited Y-axis decrease more than $-2^{\circ}$ was classified to the Counterclockwise rotation group. For the comparison of each group, a total of 22 morphologic variables were employed and the data were analyzed by means of computer morphometrics and statistical methods. On the basis of the finding of this study, the following trends were established. 1. The Parallelwise group was $75\%$, the Clockwise rotation group was $12.5\%$ and the Counter-clockwise rotation group was $12.5\%$. 2. The growth pattern of cranial base was related to the rotation of mandible. 9. Maxillary prognathism was occured in the Counterclockwise rotation group and the rotation of palatal plane was occured in the Clockwise rotation group. 4. Mandibular prognathism was occured in the Parallelwise and the Counterclockwise rotation groups, especially in the Counterclockwise rotation group. 5. The degree of maxillo-mandibular divergency was constant in the Clockwise rotation group but decreased in the Counterclockwise rotation and the Parallelwise groups, especially in the Counterclockwise group. 6. There were no differences in the size of the anterior upper facial height (N-ANS) and the posterior lower facial height ((Go-Me)-PNS) but there were differences in the size of the anterior lower facial height (ANS-Me) and the posterior upper facial height ((S-N)-PNS) between each group. 7. The growth increment and the size of the facial depth was not related to the growth pattern of the face but the growth increment and the size of the facial height was related to the growth pattern of the face. 8. Proportional change due to the facial growth rotation was concentrated in the anterior lower face. 9. The most apparent difference between each group was happened in the size of the posterior cranial base (S-Ba) and the facial length (S-Gn).

• The korean journal of orthodontics
• /
• v.34 no.2 s.103
• /
• pp.121-129
• /
• 2004

The purpose of this study was to photoelastically visualize 4he distribution of fortes transmitted to the alveolus and surrounding structures using three different types of headgear for the distal movement of the upper molars. A photoelastic maxillary model was made and three different directional forces applied, which were high-pull, straight-pull, and cervical-pull. Stress distribution was recorded through circular polariscope, and two-dimensional photoelastic stress analysis was performed according to isochromatic fringe characteristics. The results were as follows: 1. In the case of high-pull headgear bodily movement occurred in the medium- length outer bow, stress distribution in the apical region was 1st molar, 2nd premolar, lst premolar in sequence and there was no apparent difference. 2. In the case of straight-pull headgear, bodily movement occurred in the long outer bow and stress distribution in the apical region was heavy in the 1st molar, 2nd premolar, 1st premolar in sequence. But. there were no apparent differences according to the length of the outer bow. 3. In the case of cervical- pull headgear, bodily movement also occulted in 4he long outer bow, and apical stress of the premolar region was heaviest among other cases and apical stress of the 2nd premolar was heaviest in the short outer bow. In clinical situations, to achieve bodily movement of the upper 1st molars without modifying outer bow height, applying an outer bow length as long as the inner bow length in high-pull headgear and applying an outer bow length longer than the inner bow length in straight-pull, cervical-pull headgear are recommended.

• The korean journal of orthodontics
• /
• v.32 no.1 s.90
• /
• pp.1-7
• /
• 2002

The purposes of this study were to observe the compensation pattern of human female adults with openbite tendency and to provide the decision criteria of the diagnosis and treatment planning for those patients. Fifty patients with anterior openbite and fifty-five Patients without anterior openbite patients were selected as a control and a test group. ODI of the all patients was below 66. Mean ages of the control and the test group were 23.88 ${\pm}$ 4.53 and 24.7 ${\pm}$ 6.20 years, respectively. Lateral cephalograms were taken and forty-one variables were measured. To identify the morphological differences between the groups, statistical analyses were performed. Statistically significant differences were found in the measured variables of lower face height, N-Me, ANS-Me, ANS-Me/N-Me ratio, Mx1-SN, Mx1-FH, Mx1-NA(mm), Mx1-APo, PP to Mx6, Mn1-NB(degree), Mn1-NB(mm). The test group showed decreased lower face height, N-Me, ANS-Me, ANS-Me/N-Me ratio, more uprighted and retruded maxillo-mandibular incisors. Overeruption of the maxillary first molar was found in the control group.

• The korean journal of orthodontics
• /
• v.50 no.3
• /
• pp.157-169
• /
• 2020

Objective: The aim of this retrospective study was to evaluate the pre- and postsurgical bone densities at alveolar and extra-alveolar sites following two-jaw orthognathic surgery. Methods: The sample consisted of 10 patients (mean age, 23.2 years; range, 18.0-27.8 years; 8 males, 2 females) who underwent two-jaw orthognathic surgery. A three-dimensional imaging program (Invivo 5) was used with multidetector computed tomography images taken pre- and postoperatively (obtained 32.3 ± 6.0 days before surgery and 5.8 ± 2.6 days after surgery, respectively) for the measurement of bone densities at the following sites: (1) alveolar bone in the maxilla and mandible, (2) extra-alveolar sites, such as the top of the head, menton (Me), condyle, and the fourth cervical vertebrae (C4). Results: When pre- and postsurgical bone densities were compared, an overall tendency of decrease in bone density was noted. Statistically significant reductions were observed in the densities of cancellous bone at several areas of the maxillary alveolar bone; cortical and cancellous bone in most areas of the mandibular alveolar bone; cortical bone in Me; and cancellous bone in C4. There was no statistically significant difference in bone density in relation to the depth of the alveolar bone. In a comparison of the bone densities between groups with and without genioplasty, there was almost no statistically significant difference. Conclusions: Accelerated tooth movement following orthognathic surgery may be confirmed with reduced bone density. In addition, this study could offer insights into bone metabolism changes following orthognathic surgery, providing direction for further investigations in this field.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.25 no.2
• /
• pp.399-408
• /
• 1995

The purpose of this study was to obtain information on the clinical and radiographic features of the dentigerous cysts in the jaws. For this study, the authors examined and analysed the clinical records and radiographs of 233 patients who had lesions of dentigerous cyst diagnosed by clinical and radiographic or histopathological examinations. And the obtained results were as follows: 1. Dentigerous cysts occurred the most frequently in the 2nd decade(38.2％) and occurred more frequently in males(67.4％) than in females(32.6％). 2. The most common clinical symptom was swelling of the jaw(33.9％), and the lesions were treated by the method of surgical removal. 3. The type of lesions was mainly observed as central type(72.5％), and size of the lesion was most frequently observed 2 - 2.9cm in the widest length. 4. The lesions were most frequently observed well-defined outline with hyperostotic border(49.8％), and smooth margin(73.4％), and homogeneous lesional radiolucency(79.4％). 5. Cortical thinning and expansion of the lesions(82.0％) were observed, and their direction were most frequently observed toward buccal side(64.0％). 6. The effect on the causative tooth were observed as tooth displacement(41.2％) and delayed root development(l9.3％), and the distance between cemento-enamel junction and lesional wall attachment of the causative tooth was mainly observed as below 2mm(79.6％). 7. The effect on the adjacent tooth were observed as loss of lamina dura(66.8％), root resorption(33.9％), and tooth displacement(31.5％). 8. The effects on the adjacent anatomic structures were observed as displacement of the mandibular canal(46.5％) and maxillary sinus or nasal cavity(72.2％).