• 한국기계가공학회지
• /
• 제12권6호
• /
• pp.77-83
• /
• 2013

Orthodontics is a branch of dentistry that is concerned with the study and treatment of malocclusion, which may result from tooth irregularities, disproportionate jaw relationships, or both. Orthodontic devices consist of brackets, archwire connected to each bracket, and bends and hooks for auxiliary functions. Basically, orthodontics involves the interaction of brackets and archwire. It should be noted that uncontrolled tipping can occur due to unwanted movement of the teeth. The bending of an archwire can control the angle of an archwire and the rotation of a tooth. In this study, we predict the relationship between the bending angle of an archwire and the rotation of a tooth using the Kriging interpolation method. Also, we calculate the angle of an archwire that occurs at the minimum value of tooth rotation.

• 대한치과교정학회지
• /
• 제49권6호
• /
• pp.393-403
• /
• 2019

Objective: Sliding mechanics using orthodontic miniscrews is widely used to stabilize the anchorage during extraction space closure. However, previous studies have reported that both posterior segment displacement and anterior segment displacement are possible, depending on the mechanical properties of the archwire. The present study aimed to investigate the effect of archwire stiffness and friction change on the displacement pattern of the maxillary posterior segment during anterior segment retraction with orthodontic miniscrews in sliding mechanics. Methods: A three-dimensional finite element model was constructed. The retraction point was set at the archwire level between the lateral incisor and canine, and the orthodontic miniscrew was located at a height of 8 mm from the archwire between the second premolar and first molar. Archwire stiffness was simulated with rectangular stainless steel wires and a rigid body was used as a control. Various friction levels were set for the surface contact model. Displacement patterns for the posterior and anterior segments were compared between the conditions. Results: Both the anterior and posterior segments exhibited backward rotation, regardless of archwire stiffness or friction. Among the conditions tested in this study, the least undesirable rotation was found with low archwire stiffness and low friction. Conclusions: Posterior segment displacement may be unavoidable but reducing the stiffness and friction of the main archwire may minimize unwanted rotations during extraction space closure.

• 융복합기술연구소 논문집
• /
• 제7권2호
• /
• pp.17-20
• /
• 2017

Orthodontic treatment is accomplished by attaching an archwire to a bracket on tooth. The shape of the archwire is usually planned from 3-D scanned data of patient's teeth. It is manufactured by bending a metal wire and there have been some researches in progress to automate it. In this paper, we propose a method to obtain the bending angle at the bending point from the shape data of the archwire and verify it by simulation using actual archwire data.

• 대한치과의사협회지
• /
• 제55권12호
• /
• pp.850-860
• /
• 2017

Orthodontic treatment with premolar extraction is usually performed to correct bialveolar protrusion. These methods require the use of stiff rectangular working archwire which requires lengthy alignment and leveling before insertion. In this case report, interproximal reproximation was performed instead of extraction. To establish clearance between the archwire and resin domes fixing the archwire, an archwire was inserted into a water-soluble tube before fabricating resin domes. This tube is solved away by the saliva. During fabrication of resin domes, the archwire was deflected intentionally reflecting the displacement of teeth from their ideal position. This can be called as deflection-based bonding (DBB) technique. DBB is different from conventional method of positioning the brackets on its ideal position and then inserting an archwire to align the brackets. Because the orthodontic force of the archwire comes from its deflection from passive configuration, deflecting an archwire as needed can move the teeth more predictably than just bonding brackets on its ideal position. Also, areas with good alignment before orthodontic treatment can be maintained simply by not deflecting the archwire during bonding in these areas. After initial alignment, interproximal reproximation was performed to create 4.8 mm space in the maxillary arch and 4.2 mm space in the mandibular arch. These spaces were closed using orthodontic mini-implant anchorage thus retracting the maxillary incisors 4 mm posteriorly accompanied with 0.7 mm and 0.3 mm distal movement of right and left molars. By using interproximal reproximation and water-soluble tube with DBB, mild bialveolar protrusion was successfully treated without extraction.

• 대한치과교정학회지
• /
• 제30권4호
• /
• pp.377-386
• /
• 2000

경미하거나 중등도의 골격성 비대칭을 동반한 치열 정중선 불일치를 치료할 때 진단시 간과한 경우 교정치료의 마무리시기에 발견하여 치료기간이 더 길어지거나 만족스럽지 못한 결과를 초래하게 된다. 이때 비대칭 악간 고무줄을 사용한 통상적인 방법으로 장기간 치료하면 교합평면이 변화되거나 치아가 경사 이동되는 등 여러 가지 부작용들이 발생할 수 있다. 이를 예방하기 위해 초진시부터 세심한 진단과 정확한 역학의 적용이 필요하다. Dr. Burstone이 제안한 three-piece basal archwire는 posterior anchorage unit, anterior segment와 intrusion arch 로 구성된다. Three-piece basal archwire는 전치부 함입과 후방견인을 동시에 도모할 수 있으며, 기울어진 전치부 교합평면의 개선도 가능하다. 편측으로만 견인력을 적용하여 치열 정중선을 개선할 때 절치가 경사이동되는 것을 방지하기 위해 Three-piece basal archwire를 응용하여 견인하는 방향의 반대측에 모멘트를 부가하면 절치의 편측 치체 이동을 도모할 수 있다. 이러한 방법으로 치열 정중선 불일치를 개선한 치료 증례를 살펴보고자 한다.

• 대한치과교정학회지
• /
• 제27권3호
• /
• pp.401-409
• /
• 1997

부정교합은 전후방, 측방, 수직적 부조화로 분류할 수 있는 데, 수직적인 부조화 중 과개 교합을 해소하기 위하여 환자의 상태에 따라 구치부의 정출 혹은 전치의 intrusion이 시도되고 있으며, intrusion은 여러 선학들에 의해 다양한 방법들이 사용되어지고 있다. 본 연구는 전치의 intrusion 방법으로 임상에서 많이 사용되어지고 있는 utility archwire, Burstone intrusion archwire, "J" hook headgear에 의한 상악 전치부intrusion시 초기 응력 상태를 광탄성법으로 비교 연구하기 위하여 치아와 치조골 모형을 광탄성물질로 대체시키고 wire와 bracket을 주어진 조건으로 위치시킨 후 편광판을 이용하여 초기 응력 상태를 분석하였고, 아래와 같은 결과를 얻었다. 1. utility archwire에서는 중등도의 응력이 전치부의 치근단 부위에서 비교적 균일하게 나타났고, 제1대구치의 치근단 부위에서는 집중되어 나타났다. 2. Burstone의 3-piece intrusion archwire에서는 중등도의 응력이 전치부와 구치부의 치근단 부위에서 비교적 균일하게 나타났다. 3. "J" hook headgear에서는 강한 응력이 치조골 전반과 전치부 치근단 부위에 넓게 분포되어 나타났고, 특히 중절치와 측절치 사이 치조골 부위에 가장 강한 응력을 나타냈다. 다른 군과는 달리 전체 치아의 periodontal ligament space를 따라 약한 응력이 나타났다.

• 한국기계가공학회지
• /
• 제9권6호
• /
• pp.95-100
• /
• 2010

For orthodontic treatment, most commonly, an archwire is inserted into orthodontic brackets that can be made from stainless steel. Then, the archwires interact with the brackets to move teeth into the desired positions. However, the activation of an archwire may induce undesirable rotation of a tooth due to the moment application. An appropriate magnitude of the gable bends of an archwires prevents its rotation. However, it is not easy to predict the relationship between the rotation and the gable bend. This study presents the numerical approach to predict the rotation of a tooth with respect to the gable bend in the activation of an archwire. To predict the rotation of a tooth, the kriging interpolation method is introduced.

• 대한치과교정학회지
• /
• 제25권5호
• /
• pp.525-541
• /
• 1995

상악치열에서 제 1 소구치를 발거하고, 이 위치로 견치를 후방이동시킨 상태에서 retraction archwire를 사용하여 상악 4절치를 한 묶음으로 후방견인시켰을 때 초기에 나타나는 모든 힘 체계와 개개치아의 이동양상을 살펴보고 바람직하지 않은 치아이동을 감소시키기 위한 방안을 모색하고자 본 연구를 시행하였다. 먼저 유한요소법을 이용하여 상악 치아와 치근막의 해부학적 형태 및 생체적 특성을 컴퓨터로 재현시키고 모형화된 브라켓을 부착시킨 후, beam요소를 사용하여 5종의 retraction loop를 하나씩 부여한 다섯 가지의 탄선을 모형화하고, 브라켓과 탄선간에는 gap요소를 사용하여 모형화함으로써 전체 유한요소 모형을 완성하였다. loop의 형태, activation 의 양, gable bend와 torque의 조건에 따른 차이를 검토하기 위해, 각 조건을 변화시켜 loop를 activation시켰을 때 탄선이 발휘하는 힘과 모멘트, 치아이동의 변위를 3차원적으로 정량적 및 가시적으로 평가하고 비교, 분석한 결과 다음과 같은 결론을 얻었다. 1. tear-drop loop archwire사용시 각 치아의 근원심이동 및 설측이동이 발치공간 폐쇄에 도움이 되었으나, 바람직하지 못한 상하이동과 각 방향으로의 회전이동이 부가적으로 나타났다. 2.다섯 가지의 retraction archwire중 T-loop archwire에서 공간폐쇄에 도움이 되는 치아이동이 가장 작게 나타났으며, 각 방향으로의 회전이동 역시 가장 작게 나타났다. 3. tear-drop loop archwire에서 activation양을 증가시킴에 따라 공간폐쇄에 도움이 되는 치아이동이 점차 증가했으나, 바람직하지 못한 상하이동과 각 방향으로의 회전이동이 함께 증가했다. 4. tear-drop loop archwire에서 loop의 전후방에 gable bend부여시 전치에서 근원심방향의 치체이동에 도움이 되었으나, 모든 치아에서 상하이동과 각 방향으로의 회전이동이 함께 증가했다. 5. tear-drop loop aichwire의 절치부에 치근 설측 torque 부여시 이들 치아의 순설경사를 개선시키는 효과를 얻었으나, 그 반작용으로 견치 치관의 설측회전이 크게 증가했으며, 전치의 상하이동과 모든 치아에서 각 방향으로의 회전이동이 증가했다.

• 대한치과교정학회지
• /
• 제45권1호
• /
• pp.13-19
• /
• 2015

Objective: This study aimed to compare the frictional force (FR) in self-ligating brackets among different bracket-archwire angles, bracket materials, and archwire types. Methods: Passive and active metal self-ligating brackets and active ceramic self-ligating brackets were included as experimental groups, while conventional twin metal brackets served as a control group. All brackets were maxillary premolar brackets with 0.022 inch [in] slots and a $-7^{\circ}$ torque. The orthodontic wires used included 0.018 round and $0.019{\times}0.025$ in rectangular stainless steel wires. The FR was measured at $0^{\circ}$, $5^{\circ}$, and $10^{\circ}$ angulations as the wire was drawn through the bracket slots after attaching brackets from each group to the universal testing machine. Static and kinetic FRs were also measured. Results: The passive self-ligating brackets generated a lower FR than all the other brackets. Static and kinetic FRs generally increased with an increase in the bracket-archwire angulation, and the rectangular wire caused significantly higher static and kinetic FRs than the round wire (p < 0.001). The metal passive self-ligating brackets exhibited the lowest static FR at the $0^{\circ}$ angulation and a lower increase in static and kinetic FRs with an increase in bracket-archwire angulation than the other brackets, while the conventional twin brackets showed a greater increase than all three experimental brackets. Conclusions: The passive self-ligating brackets showed the lowest FR in this study. Self-ligating brackets can generate varying FRs in vitro according to the wire size, surface characteristics, and bracket-archwire angulation.

• 대한치과교정학회지
• /
• 제51권4호
• /
• pp.270-281
• /
• 2021

Objective: The aim of this in vitro study was to evaluate the changes in friction between orthodontic brackets and archwires coated with aluminum oxide (Al₂O₃), titanium nitride (TiN), or chromium nitride (CrN). In addition, the resistance of the coatings to intraoral conditions was evaluated. Methods: Stainless steel canine brackets, 0.016-inch round nickel-titanium archwires, and 0.019 × 0.025-inch stainless steel archwires were coated with Al₂O₃, TiN, and CrN using radio frequency magnetron sputtering. The coated materials were examined using scanning electron microscopy, an X-ray diffractometer, atomic force microscopy, and surface profilometry. In addition, the samples were subjected to thermal cycling and in vitro brushing tests, and the effects of the simulated intraoral conditions on the coating structure were evaluated. Results: Coating of the metal bracket as well as nickel-titanium archwire with Al₂O₃ reduced the coefficients of friction (CoFs) for the bracket-archwire combination (p < 0.01). When the bracket and stainless steel archwire were coated with Al₂O₃ and TiN, the CoFs were significantly lower (0.207 and 0.372, respectively) than that recorded when this bracket-archwire combination was left uncoated (0.552; p < 0.01). The friction, thermal, and brushing tests did not deteriorate the overall quality of the Al₂O₃ coatings; however, some small areas of peeling were evident for the TiN coatings, whereas comparatively larger areas of peeling were observed for the CrN coatings. Conclusions: Our findings suggest that the CoFs for metal bracket-archwire combinations used in orthodontic treatment can be decreased by coating with Al₂O₃ and TiN thin films.