• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제36권5호
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• pp.375-379
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• 2010

Introduction: In the management of dentofacial deformities, variable movement of the maxilla can be made possible by a Le Fort I osteotomy. Posterior impaction of the maxilla necessary for rotation of the maxillomandibular complex enhances the functions and esthetic results. In cases of posterior impaction of the maxilla, an increase in the figure of the occlusal plane angle and incisor inclination can occur. This study reports the relationship between the amount of posterior impaction and the change in the occlusal plane angle and incisor inclination in a Le Fort I osteotomy by preoperative and postoperative lateral cephalograms. Materials and Methods: Twenty patients who had undergone orthognathic surgery in Dong-A University Medical Center participated in this study. Lateral cephalometrics, within 3 weeks prior to surgery and 3 days after surgery, were used for analysis. Pre and postoperative measurements of the occlusal plane angle and incisal inclination based on the Frankfort horizontal (FH) plane were performed. X and Y were defined as the amount of vertical change in the upper incisor tip and the amount of vertical change in the upper first molar mesial cup tip through the operation. The amount of final posterior maxillary impaction was determined by subtracting Y from X, which is the difference in vertical height. According to the amount of posterior maxillary impaction, the change in the occlusal plane angle and incisal inclination was measured. Results: The average posterior maxillary impaction was 2.91 mm and the average change in the occlusal plane angle and incisal inclination was $6.54^{\circ}$after surgery. As a result, each mm of posterior maxillary impaction changed the occlusal plane angle and incisal inclination by $2.25^{\circ}$. Statistically, there was high significance. Two cases were observed: one with the same amount of posterior maxillary impaction performed on both the right and left showing $2.20^{\circ}$, and the other with a different amount of posterior maxillary impaction performed showing $2.35^{\circ}$. In this case, there was no significance difference between the two cases. Conclusion: Each mm of posterior maxillary impaction changes the occlusal plane angle and incisal inclination by an average of $2.25^{\circ}$. In posterior maxillary impaction, there was no significant difference in the amount of change in the occlusal plane angle and incisal inclination regardless of whether there was an equal amount of posterior maxillary impaction on both sides. This study is expected to help in the presurgical orthodontic preparation and presurgical treatment planning.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권6호
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• pp.404-412
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• 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.

• 대한치과교정학회지
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• 제50권4호
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• pp.249-257
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• 2020

Objective: To evaluate the changes in the nose in three dimensions after Le Fort I osteotomy in patients with skeletal Class III malocclusion. Methods: The subjects were 40 adult patients (20 females and 20 males; mean age, 20.3 ± 3.0 years; range, 17.0 to 31.1 years) who underwent one-piece Le Fort I osteotomy with maxillary advancement and impaction treatment for maxillary hypoplasia. The mean maxillary advancement was 4.56 ± 1.34 mm, and the mean maxillary impaction was 2.03 ± 1.04 mm. Stereophotogrammetry was used to acquire three-dimensional images before and at least 6 months after surgery. Results: Alare (Al) and alare curvature (Ac) points had moved vertically and anterolaterally postoperatively. A significant increase was observed in the nasal ala width and alar base width, and no changes were noted in the columellar length, nasolabial angle, and nasal area. There was a significant relationship between maxillary impaction and nasal ala width and horizontal and sagittal positions of the bilateral Al and Ac. The only relationship found was between maxillary advancement and postoperative sagittal location of the subnasale and pronasale. Conclusions: Nasal soft tissues were highly affected by the vertical movement of the maxilla; however, the soft tissue responses were individual-dependent.

• 대한치과의사협회지
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• 제10권5호
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• pp.277-278
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• 1972

The author have reported 2 cases for the unusual transmigration of Canine in maxillary and mandible. Transmigrated Tooth was the left buccal side between normal canine & 1st premoral in lower, and the right horizontal impaction on normal canine in upper.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제33권2호
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• pp.185-189
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• 2011

Tooth impaction represents the stop of eruption by clinical and radiographical disturbance in eruption path or the dislocation of tooth germ. The most common factor in tooth eruption disorders are spacial deficiency with other causes reported to be odontogenic tumors, periodontal ligament injury, etc. Impaction of the mandibular second molar is relatively rare and reported in about 3 out of 1,000 people. Because the second molars tend to erupt in a mesial direction, this situation can lead to serious problems if untreated, including dental caries, periodontal disease and root resorption of the first molar. Treatment of this problem includes, surgical repositioning and orthodontic forced eruption. Because each procedure have the definite advantages and disadvantages, and influenced by circumferential environment, these have limits for successfu1 recovery as independent treatment. In a case at St. Mary's Hospital, we performed successful correction of a horizontal impacted mandibular second molar using a miniplate skeletal anchorage system. We introduce this treatment as a valid method for an impacted second molar and consider a oromaxillofacial surgeon's role in tooth movement treatment.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제22권3호
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• pp.310-318
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• 2000

The purpose of this study was to assess the soft tissue changes of upper lip & nose using 38 patients who treated with Le Fort I osteotomy for the correction of dentofacial deformities. Patients were devided into three groups. One was advancement group of maxilla(Group I, N=14), another was impaction group of maxilla(Group II, N=12) and the other was combination group(advancement & impaction)(Group III, N=12). Preop. and 1 month postop. (T1), preop. and 6 months postop.(T2) were analyzed and compared. The results obtained were as follows : 1. The upper lip thickness(UL-VP) moved anteriorly approximately 62% of the horizontal maxillary change and this was significant in the advancement group(Group I) 2. The upper lip length(Stm-Sn) and the lower border of upper lip(Stm) moved superiorly 25%, 40% of the maxillary impaction group(Group II) (P<0.05) 3. There was significancy in the upper lip thicness(UL-VP) approximately 56% of the combination group(Group III) (P<0.05) 4. The nasolabial angle decreased in all groups, but there were no significancy.

• 한국분무공학회지
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• 제1권4호
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• pp.40-45
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• 1996

This Paper addresses to spray characteristics in w-shaped diesel engine combustion chamber which has impingement parts for 4 sprays injected from an injector. The two-dimensional shapes have been chosen to avoid the difficulties for analysing the spray dynamics in the real chamber. The simple shapes are reproduced with same geometries in vertical or horizontal sections through the impingement lands. The spray developments are visualized with a high speed drum camera and shadowgraphy optical system, and the droplet sizes are measured by Malvern system. The detailed discussions m made for the two different combustion chamber shapes, which are new w-shape using spray wall impaction and general w-shape. The results show that the spray characteristics of the new shape are superior to those of the general w-shape.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권3호
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• pp.155-158
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• 2022

Objectives: The aim of this study was to observe the relationship between impacted mandibular third molars and development of temporomandibular joint (TMJ) disorders. Knowledge of the factors that have an adverse effect on the TMJ is necessary for proper diagnosis, treatment, and prognosis of TMJ disorders. Materials and Methods: The study was performed on 80 patients aged between 20 and 60 years with impacted mandibular third molars, over a period of two months. The patients were examined clinically and radiologically to determine the type of impaction and detect the associated TMJ symptoms or disorders. Results: In the 80 patients, 63.8% (51/80) of TMJ disorders were found in the horizontal group, 46.3% (37/80) in the mesioangular group, 42.5% (34/80) in the distoangular group, and 30.0% (24/80) in the vertical group of impacted mandibular third molars. Conclusion: The study concluded that type of impacted mandibular third molar is factor in the development of temporomandibular disorders.

• 한국입자에어로졸학회지
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• 제18권4호
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• pp.129-136
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• 2022

The line width of circuits in semiconductor devices continues to decrease down to a few nanometers. Since nanoparticles attached to the patterned wafer surface may cause malfunction of the devices, it is crucial to remove the contaminant nanoparticles. Physical cleaning that utilizes momentum of liquid for detaching solid nanoparticles has recently been tested in place of the conventional chemical method. Dropwise impaction has been employed to increase the removal efficiency with expectation of more efficient momentum exchange. To date, most of relevant studies have been focused on drop spreading behavior on a horizontal surface in terms of maximum spreading diameters and average spreading velocity of drop. More important is the local liquid velocity at the position of nanoparticle, very near the surface, rather than the vertical average value. In addition, there are very scarce existing studies dealing with microdroplet impaction that may be desirable for minimizing pattern demage of the wafer. In this study, we investigated the local velocity distribution in spreading liquid film under various impaction conditions through the CFD simulation. Combining the numerical results with the particle removal model, we estimated an effective cleaning diameter (ECD), which is a measure of the particle removal capacity of a single drop, and presented the predicted ECD data as a function of droplet's velocity and diameter particularly when the droplets are microns in diameter.

• 대한소아치과학회지
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• 제47권2호
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• pp.219-227
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• 2020

치아 맹출은 치조골을 통해 치낭의 위치로부터 구강 내의 최종적인 교합 위치까지 치아가 이동해가는 복잡한 발육 과정이다. 치아의 맹출 장애는 맹출 일련의 단계 중 어느 단계에서도 일어날 수 있으며, 하악 제2유구치의 일차성 만기잔존과 하악 제1대구치의 수평 매복이 동시에 발생한 증례는 매우 드물다. 이번 연구의 목적은 제2유구치의 일차성 만기잔존이 동반된 하악 제1대구치의 수평매복의 두 증례에 대한 치료를 제시하는 것이다. 일차성 만기잔존으로 맹출 지연된 하악 제2유구치는 발치하였고, 수평매복된 하악 제1대구치는 교정적 견인을 시행하였다. 이후 계승 소구치의 맹출 공간을 위해 공간획득을 도모하였고 계승 소구치의 변위가 개선되었으며 제1대구치는 정상적인 맹출이 유도되었다.