• 대한치과교정학회지
• /
• 제21권2호
• /
• pp.353-366
• /
• 1991

This study was performed to analyze the effects of forces to the alveolar bone by various molar uprighting spring such as helical uprighting spring. T-loop spring, Modified T-loop spring and open coil spring. The simplified two-dimensional photoelastic model was constructed with a lower left posterior quadrant containing the second molar, the first and second premolars and the canine, with the first molar missing. Several molar uprighting springs were fabricated from 0.017 by 0.022 inch blue Elgiloy and applied to the photoelastic model. Two-dimensional photoelastic stress analysis was performed, and the stress distribution was recorded by photography The results obtained were as follows; 1. In all the kinds of the springs, the center of rotation of the mandibular second molar was oserved at the apical 1/5-1/6 between the alveolar crest and the root apex. 2. In all the kinds of the spring, the stress induced in the mesial root surface of the mandibular second molar was relatively homogeneous but there was some difference in the magnitude of the stress. 3. In the kinds of the springs, the distal crown tipping moment of the second molar was increased in turn as open coil spring, helical uprighting spring, T-loop spring, and modified T-loop spring. 4. The largest extrusive force was occured in the T-loop spring, intrusive force was occured in Modified T-loop spring only, and the largest distal tipping force was occured in open coil spring. 5. In the T-loop spring with activation, the stress induced in the mesial root surface of the second molar was increased gradually from the root apex to the alveolar crest and highly concentrated in the alveolar crest.

• 대한치과교정학회지
• /
• 제26권6호
• /
• pp.691-703
• /
• 1996

Three-dimensional finite element model was made from adult skull to find desirable direction of retraction force to treat skeletal class II malocclusion. The retraction force of 400g was applied to the first molar. The direction of the force application was $23^{\circ}$ downward, parallel, $23^{\circ}$ upward and $45^{\circ}$ upward to the occlusal plane. The stress distribution and the displacement within the maxilla were analyzed by three-dimensional finite element method. The findings obtained were as follows: 1. Maxillary first molar was displaced posteriorly and inferiorly in $23^{\circ}$ downward, parallel, $23^{\circ}$ upward retraction but it was displaced posteriorly and superiorly in $45^{\circ}$ upward retraction. 2. ANS, A point and prosthion were moved posteriorly and inferiorly and pterygomaxillary fissure was moved posteriorly and superiorly. Clockwise rotation of maxilla occurred when retraction force was applied. 3. The degree of clockwise rotation of maxilla was greatest when the force was applied $23^{\circ}$ upward to the occlusal plane and was least when the force was applied $23^{\circ}$ downward to the occlusal plane. 4. Large tensile stress appeared in maxillary first molar and alveolar bone and the infraorbital region of maxilla when the force was applied $23^{\circ}$ downward to the occlusal plane. Tensile stress was smaller as the direction of force move upward. 5. Large compressive stress was appeared in maxillary first molar and infraorbital region in $45^{\circ}$ upward case and large compressive stress occurred in the posterior part of maxilla as the retraction force was upward.

• 대한치과교정학회지
• /
• 제53권2호
• /
• pp.125-136
• /
• 2023

Before progress was recently made in the application of temporary anchorage devices (TADs) in bio-mechanical design, orthodontists were rarely able to intrude molars to reduce upper posterior dental height (UPDH). However, TADs are now widely used to intrude molars to flatten the occlusal plane or induce counterclockwise rotation of the mandible. Previous studies involving clinical or animal histological evaluation on changes in periodontal conditions after molar intrusion have been reported, however, studies involving human histology are scarce. This case was a Class I malocclusion with a high mandibular plane angle. Upper molar intrusion with TADs was performed to reduce UPDH, which led to counterclockwise rotation of the mandible. After 5 months of upper molar intrusion, shortened clinical crowns were noticed, which caused difficulties in oral hygiene and hindered orthodontic tooth movement. The mid-treatment cone-beam computed tomography revealed redundant bone physically interfering with buccal attachment and osseous resective surgeries were followed. During the surgeries, bilateral mini screws were removed and bulging alveolar bone and gingiva were harvested for biopsy. Histological examination revealed bacterial colonies at the bottom of the sulcus. Infiltration of chronic inflammatory cells underneath the non-keratinized sulcular epithelium was noted, with abundant capillaries being filled with red blood cells. Proximal alveolar bone facing the bottom of the gingival sulcus exhibited active bone remodeling and woven bone formation with plump osteocytes in the lacunae. On the other hand, buccal alveolar bone exhibited lamination, indicating slow bone turnover in the lateral region.

• 대한치과교정학회지
• /
• 제45권2호
• /
• pp.82-88
• /
• 2015

Objective: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. Methods: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. Results: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. Conclusions: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

• 대한치과교정학회지
• /
• 제24권3호
• /
• pp.555-567
• /
• 1994

The purpose of this study is to observe the effect of high pull headgear on the craniofacial structures of mixed dentition with Class II malocclusion. The cephalometric headplates of 16 children treated by high pull headgeaar during 6 months and 18 children during 12 months were traced, digitized and statistically analyzed. The results were as follows. 1. Inhibition of foreward growth of maxilla was observed in both group. 2. Clockwise rotation of maxilla was observed in both group. 3. There were distal movement of maxillary 1st molar and inhibition of alveolar bone growth of maxilla. 4. There was compensatory extrusion on mandibular 1st molar. 5. The ratio of anterior facial height to posterior facial height was almostly not changed. In the treatment plan of C II malocclusion by high pull headgear, ire must prevent the mandibulasr 1st molar from extruding and for orthopedic effect, at least 6 months is needed.

• 대한치과교정학회지
• /
• 제31권6호
• /
• pp.559-566
• /
• 2001

본 연구는 설측 이소맹출된 하악 제2대구치의 협측 반대교합을 개선하기 위해 사용되는 mandibular posterior crossbite appliance에 의해 하악 제2대구치의 치근단과 그 주위의 치조골에 발생되는 응력분포를 알아보기 위해 광탄성법을 이용하여 분석하였다. 하악의 치조골을 재현하기 위해 PL-3 형의 epoxy resin과 PL-3 보다 경질인 레진치아를 사용하여 설측 이소맹출된 하악 제2대구치를 광탄성모형으로 재현하였다. 광탄성 모현상에 mandibular posterior crossbite appliance를 적용하고 힘을 가하기 전과후의 응력 분포를 알아보기 위해 원형편광기 를 사용하여 모형의 전후방에서 관찰하였다. 이상의 연구를 통해 얻어진 결과는 다음과 같다. 1. 하악 제2대구치의 협측면에 힘을 가한 경우, 설측 치조정과 치근첨 부위에 응력이 집중되어 나타났고 회전중심이 치근 협측면의 중간 1/3부위와 치근첨 부위에 발생하였으며 이로 인해 제 2대구치에 협측으로의 비조절성 경사이동 및 회전력이 발생하였다. 2. 하악 제2대구치의 설측면에 힘을 가한 경우에는 협측면에 힘을 가한 경우 보다 치근첨에 더 많은 응력이 발생하였다. 또한 치근하방의 치조골 부위에 응력이 증가하였으며 치근의 협측면과 치근첨 부위의 회전중심도 없어져 이로 인한 협측으로의 조절성 경사 이동 및 함입력이 관찰되었다. 3. 하악 제2대구치의 협측이나 설측에 힘을 가한 경우, 고정원인 제1대구치의 치근첨 부위는 힘을 가하기 전의 초기 응력상태와 비교할 때 응력의 증가는 보이지 않아 구치부 협측 반대 교합의 개선시 하악의 설측 호선은 효과적인 고정원으로 사용될 수 있다. 이상의 연구 결과는 설측 이소맹출된 하악 제2대구치의 구치부 협측 반대교합을 개선하기 위해 사용되는 mandibular posterior crossbite appliance를 적용할 때, 제2대구치의 협측면보다는 설측면에서 힘을 부여하는 것이 교합장애를 야기시킬 수 있는 비조절성 경사이동과 구치의 회전을 피하면서 협측으로의 조절성 경사이동 및 함입력을 적용시킬 수 있음을 의미한다.

• 대한치과교정학회지
• /
• 제18권2호
• /
• pp.367-385
• /
• 1988

In case of skeletal Class III malocclusion with underdeveloped maxilla, the extraoral orthopedic force for the stimulation of maxillary growth or anterior reposition of the maxilla has been used clinically for the improvement of facial skeletal relationship. The purpose of this investigation was to examine the initial reaction of maxillofacial complex to the maxillary protraction by using extraoral orthopedic force. The dried human skull was used and this investigation was done by means of double exposure holographic interferometry. The protraction forces placed on the canine or the first molar were parallel, $10^{\circ}$ downward, $20^{\circ}$ downward to the occlusal plane. Fringe pattern of each protraction condition was compared and analized. The results were as follows: 1. Each maxillofacial bone displaced saparately. 2. More displacement was shown at the area of the teeth and the alveolar bone. 3. A counterclockwise rotation of the maxilla wa decreased by downward protraction and especially 20 degree downward protraction from the canine showed least rotation. 4. On the zygomatic arch, outward bend was observed and this effect was decreased by downward protraction. 5. On the zygomatic bone, the counter clockwise rotation was increased by the downward protraction. 6. When maxillary expansion was applied at the same time, outward and upward displacement with counterclockwise rotation was observed on the maxilla. 7. The lateral pterygoid plate of sphenoid bone was affected by maxillary protraction.

• 대한소아치과학회지
• /
• 제37권1호
• /
• pp.130-135
• /
• 2010

이소맹출은 치아가 비정상적인 위치로 맹출하는 경우를 말하며, 주로 상악 제1대구치, 하악 측절치, 상악 견치에서 발생하며 하악 제1대구치에서는 드물게 발생한다. 제1대구치의 이소맹출은 흔히 제2유구치의 비정상적인 치근흡수를 야기하며, 이를 방치하게 되면 제2유구치의 조기상실, 제1대구치의 근심경사 및 회전, 제2소구치의 맹출 공간 부족 및 교합문제 등을 야기하게 되므로 이소맹출로 진단될 경우 조기 치료가 추천된다. 이소맹출은 대개 통상적인 방사선검사를 통해 발견되나, 간혹 제2유구치의 치근흡수가 심할 경우 치수가 감염되어 동통을 야기하는 경우도 있다. 이소맹출의 치료는 제2유구치를 보존하면서 제1대구치의 맹출 방향을 바로 잡아 주는 것으로 크게 치간이개(interproximal wedging)와 원심경사이동(distal tipping)을 이용한 방법을 사용한다. 본 증례들은 하악 제1대구치의 이소맹출을 보이는 환아들로, Humphrey appliance와 Halterman appliance를 이용하여 양호한 치료 결과를 얻었기에 보고하는 바이다.

• 대한치과교정학회지
• /
• 제47권4호
• /
• pp.268-274
• /
• 2017

The purpose of this article is to introduce a simple appliance that uses a setup model and a nickel-titanium (Ni-Ti) wire for correcting the mesial rotation and drift of the permanent maxillary first molar. The technique involves bonding a Ni-Ti wire to the proper position of the target tooth on a setup model, followed by the fabrication of the transfer cap for indirect bonding and its transfer to the patient's teeth. This appliance causes less discomfort and provides better oral hygiene for the patients than do conventional appliances such as the bracket, pendulum, and distal jet. The treatment time is also shorter with the new appliance than with full-fixed appliances. Moreover, the applicability of the new appliance can be expanded to many cases by using screws or splinting with adjacent teeth to improve anchorage.

• 대한치과교정학회지
• /
• 제20권2호
• /
• pp.355-361
• /
• 1990

This study was undertaken to finish the design of the adequate preadjusted bracket in Korean. The labio-lingual & bucco-lingual width of tooth & in-and-out of the bracket base was studied in normal occlusion of 17 males & 17 females. The following results were obtained. 1. The in-and-outs of the bracket base in Korean were obtained (table 2). 2. The in-and-outs of the premolar & molar were no significant due to variation according to arch wire shape in clinical practice, so the more adjustment of arch wire was required. 3. The more amount of offset was required at lateral-canine offset than at central-lateral offset in 1st order bending, due to difference of the in-and-out. 4. The degrees of the anti-rotation in molar were obtained (table 3).