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1.
Orthod Craniofac Res ; 24 Suppl 1: 31-38, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33652500

RESUMO

INTRODUCTION: The purpose of this study was to evaluate the long-term position of erupted third molars after maxillary total arch distalization using modified C-palatal plates (MCPPs) in adolescents and to identify factors associated with these positions. SETTING AND SAMPLE POPULATION: Sixty-two third molars (male: 20, female: 42) in Class II patients treated with MCPPs and thirty-nine teeth for the Control group (male: 22, female: 17). MATERIALS AND METHODS: Samples were analyzed using panoramic radiographs taken initially (T0), after treatment (T1) and after >3 years retention (T2). Third molars were classified as downward (Group A, N = 31; males: 12, females: 19) and upward (Group B, N = 31; males: 8, females: 23) based on their vertical position after treatment. Analysis of variance and multiple logistic regression analysis were performed. RESULTS: The vertical position of the third molars of Group A, Group B, and the Control showed a 2.2, 3.5 and 2.7 mm downward movement at T2. However, there was no difference in the amount of third molar eruption among the groups. Regarding factors affecting the vertical distance of the third molar, Age, C8-OP, ∠8-OP and D7-T at the initial affected vertical position of the third molars after molar distalization (P < .05). CONCLUSIONS: Group A and B showed no difference in the third molar eruption during retention after total arch distalization. This study suggests that it might be unnecessary to extract the developing third molar before molar distalization in Class II adolescents.


Assuntos
Má Oclusão de Angle Classe II , Dente Serotino , Adolescente , Cefalometria , Feminino , Humanos , Masculino , Maxila/diagnóstico por imagem , Dente Molar/diagnóstico por imagem , Dente Serotino/diagnóstico por imagem , Dente Serotino/cirurgia , Técnicas de Movimentação Dentária
2.
Artigo em Inglês | MEDLINE | ID: mdl-33736907

RESUMO

INTRODUCTION: The purpose of this study was to analyze and clarify tooth movement during mesialization of the whole maxillary dentition with various force angulations (FAs). METHODS: A finite element method was used to simulate the long-term orthodontic movement of the maxillary dentition by accumulating the initial displacement of teeth produced by elastic deformation of the periodontal ligament. A mesial force of 3 N was applied to the maxillary second molar at 5 different FAs (-30°, -15°, 0°, 15°, and 30°) to the occlusal plane. RESULTS: At an FA of 28°, the line of action of the force passed through the center of resistance of the maxillary whole dentition. With all FAs, the central incisors and molars tipped labially and mesially, respectively. The tipping angles gradually decreased as the FAs shifted from -30° to 30°. The molars tipped lingually with FAs of -30° and -15°, whereas they tipped buccally with FAs of 0°, 15°, and 30°. The molars tended to rotate mesiolingually more as the angle of force increased toward an FA of 30°. The occlusal plane rotated counterclockwise with FAs of -30°, -15°, and 0°, whereas it rotated clockwise with FAs of 15° and 30°. With an FA of 30°, buccal tipping and mesiolingual rotation of the molars, and the change in the occlusal plane angle decreased when the transpalatal arch (TPA) was fixed to the first molars and decreased, even more when the TPA was fixed to the second molars rather than the first molars, when a thicker TPA was used, and when the TPA was fixed to both molars rather than a single molar. CONCLUSIONS: There was a correlation between tooth movement during mesialization of the whole maxillary dentition and the angle at which the force was applied.

3.
Am J Orthod Dentofacial Orthop ; 159(4): 470-479, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33558030

RESUMO

INTRODUCTION: The aims of this study were to evaluate the long-term skeletodental effects, the volume of maxillary tuberosity, and airway space changes after maxillary molar distalization using modified C-palatal plate (MCPP) in adolescents with Class II malocclusion. METHODS: The sample consisted of 20 adolescent patients (MCPP group; mean age, 12.9 ± 1.0 year) who underwent bilateral distalization of their maxillary dentition and 20 subjects as a control group. In the MCPP group, cone-beam computed tomography images were taken before distalization, at the end of the treatment, and during retention with a minimum of a 3-year posttreatment follow up period. Repeated measures ANOVA followed by post-hoc analysis with the Bonferroni test were used to identify significant differences between time points. RESULTS: After the long-term observation period, sagittal skeletal and dental relationships were maintained (there were no significant changes in ANB, occlusal plane angle, and overjet postretention). The vertical skeletal dimension did not change during treatment and was stable at the long-term follow-up (the mandibular plane angle and ANS-Me were relatively well maintained). The volume of the maxillary tuberosity showed no significant change during long-term retention. However, the volume was significantly smaller in the treatment group than in the control group (P <0.0001). There were no significant airway space changes after distalization and the postretention period. In addition, there was no significant difference between the MCPP and control groups. CONCLUSIONS: Improved sagittal skeletal and dental relationships because of treatment were maintained in the long-term evaluation. There was no negative long-term effect on airway space associated with the maxillary arch distalization. Therefore, these findings might be beneficial for clinicians in diagnosis and treatment planning for Class II malocclusion in adolescents.


Assuntos
Má Oclusão de Angle Classe II , Técnicas de Movimentação Dentária , Adolescente , Cefalometria , Criança , Tomografia Computadorizada de Feixe Cônico , Humanos , Má Oclusão de Angle Classe II/diagnóstico por imagem , Má Oclusão de Angle Classe II/terapia , Maxila/diagnóstico por imagem , Desenho de Aparelho Ortodôntico
4.
Am J Orthod Dentofacial Orthop ; 159(2): 234-245, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33546828

RESUMO

Autotransplantation of a mature premolar in adults can be a treatment of choice for tooth replacement when combined with well-planned orthodontic treatment. This case report describes the successful treatment of a 39-year-old patient with severe crowding and a hopelessly fractured tooth on the maxillary left side. Maxillary dental crowding was relieved by extraction of a premolar on the right side, and this extracted tooth was autotransplanted to replace the fractured tooth. A mandibular incisor was extracted to correct anterior crossbite. The total treatment period was 20 months. The treatment results showed a good long-term prognosis after transplantation of a mature premolar with normal surrounding alveolar bone level for over 6 years of follow-up. Occlusion and periodontal health were excellent in the long term.


Assuntos
Fraturas dos Dentes , Adulto , Dente Pré-Molar/cirurgia , Humanos , Incisivo , Mandíbula , Maxila , Fraturas dos Dentes/diagnóstico por imagem , Fraturas dos Dentes/cirurgia , Transplante Autólogo
5.
Orthod Craniofac Res ; 24 Suppl 1: 103-112, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33484608

RESUMO

OBJECTIVES: The aim of this systematic review is to assess the treatment effects (amount of distalization, distal tipping and vertical movement) of buccally versus palatally placed temporary skeletal anchorage devices (TSADs) on maxillary first molars during distalization. MATERIALS AND METHODS: Medline and Scopus databases were searched up to September 2020 for randomized controlled trials (RCTs) and non-randomized prospective cohort studies on maxillary molar distalization using TSADs in patients with Class II malocclusion. After study selection, data extraction and risk of bias assessment, meta-analyses were performed for the amount of distalization, distal tipping and intrusion of first molars. RESULTS: Nine studies (2 RCTs and 7 prospective studies) were included. The risk of bias of the RCTs was low to unclear. The non-randomized studies were of moderate quality. In five studies, the TSADs were placed in the infrazygomatic process while in two studies, they were placed in the buccal inter-radicular spaces, and in two studies, they were placed in the midpalatal region. The first molar distalization was 2.75 mm when buccal inter-radicular TSADs were used, but 4.07 and 4.17 mm with palatal and infrazgomatic TSADs. The palatal appliances were associated with 11.17° of distal tipping of the first molar while infrazygomatic and buccal inter-radicular TSADs resulted in 3.99° and 1.70° of tipping, respectively. CONCLUSIONS: Inter-radicular TSADs resulted in less distal tipping but also in less distalization. Palatal TSAD-supported appliances showed the greatest amount of distal tipping. Further RCTs or prospective studies on the effect of various designs of TSAD-supported distalization are warranted.


Assuntos
Má Oclusão de Angle Classe II , Procedimentos de Ancoragem Ortodôntica , Cefalometria , Humanos , Maxila , Dente Molar , Desenho de Aparelho Ortodôntico , Aparelhos Ortodônticos , Técnicas de Movimentação Dentária
6.
Angle Orthod ; 91(1): 22-29, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-33339047

RESUMO

OBJECTIVES: To compare the dental and skeletal treatment effects after total arch distalization using modified C-palatal plates (MCPPs) on adolescent patients with hypo- and hyperdivergent Class II malocclusion. MATERIALS AND METHODS: The study group included 40 patients with Class II malocclusion (18 boys and 22 girls, mean age = 12.2 ± 1.4 years) treated with MCPPs. Fixed orthodontic treatment started with the distalizing process in both groups. Participants were divided into hypo- or hyperdivergent groups based on their pretreatment Frankfort mandibular plane angle (FMA) ≤22° or ≥28°, respectively. Pre- and posttreatment lateral cephalograms were digitized, and 23 variables were measured and compared for both groups using paired and independent t-tests. RESULTS: The hyper- and hypodivergent groups showed 2.7 mm and 4.3 mm of first molar crown distalizing movement, respectively (P < .001). The hypodivergent group had a slight 2.2° crown distal tipping of first molars compared with 0.3° in the hyperdivergent group. After distalization, the FMA increased 3.1° and 0.3°, in the hypodivergent and hyperdivergent groups, respectively (P < .001). SNA decreased in the hypodivergent group, while other skeletal variables presented no statistically significant differences in the changes between the groups. CONCLUSIONS: The hypodivergent group showed more distal and tipping movement of the maxillary first molar and increased FMA than the hyperdivergent group. Therefore, clinicians must consider vertical facial types when distalizing molars using MCPPs in Class II nonextraction treatment.


Assuntos
Má Oclusão de Angle Classe II , Desenho de Aparelho Ortodôntico , Adolescente , Cefalometria , Feminino , Humanos , Masculino , Má Oclusão de Angle Classe II/diagnóstico por imagem , Má Oclusão de Angle Classe II/terapia , Maxila , Técnicas de Movimentação Dentária
7.
Angle Orthod ; 2020 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-33289781

RESUMO

OBJECTIVES: To compare the dental and skeletal treatment effects after total arch distalization using modified C-palatal plates (MCPPs) on adolescent patients with hypo- and hyperdivergent Class II malocclusion. MATERIALS AND METHODS: The study group included 40 patients with Class II malocclusion (18 boys and 22 girls, mean age = 12.2 ± 1.4 years) treated with MCPPs. Fixed orthodontic treatment started with the distalizing process in both groups. Participants were divided into hypo- or hyperdivergent groups based on their pretreatment Frankfort mandibular plane angle (FMA) ≤22° or ≥28°, respectively. Pre- and posttreatment lateral cephalograms were digitized, and 23 variables were measured and compared for both groups using paired and independent t-tests. RESULTS: The hyper- and hypodivergent groups showed 2.7 mm and 4.3 mm of first molar crown distalizing movement, respectively (P < .001). The hypodivergent group had a slight 2.2° crown distal tipping of first molars compared with 0.3° in the hyperdivergent group. After distalization, the FMA increased 3.1° and 0.3°, in the hypodivergent and hyperdivergent groups, respectively (P < .001). SNA decreased in the hypodivergent group, while other skeletal variables presented no statistically significant differences in the changes between the groups. CONCLUSIONS: The hypodivergent group showed more distal and tipping movement of the maxillary first molar and increased FMA than the hyperdivergent group. Therefore, clinicians must consider vertical facial types when distalizing molars using MCPPs in Class II nonextraction treatment.

8.
J World Fed Orthod ; 9(3): 129-136, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32873518

RESUMO

OBJECTIVE: The aim of this study was to compare the facial esthetic standards between Paraguayan and Korean beauty pageant contestants as well as to evaluate the deviation in Farkas proportion indexes (PI) from the golden ratio for each group using three-dimensional (3D) stereophotogrammetric analysis. METHODS: 3D soft tissue images of 34 Miss Paraguay (MP) and 54 Miss Korea (MK) pageant contestants were obtained. The 3D images were digitized and 52 measurements and ratios were calculated. One-way multivariate analysis of variance was applied to compare the two groups. One-sample t-test was applied to assess the differences between the PI of each group and the golden ratio. RESULTS: The MP group showed greater mouth width, total vermilion perimeter, and lower lip protrusion (P < 0.001) than the MK group. Meanwhile, the MK group showed longer forehead height and total facial height (P = 0.002 and P < 0.001, respectively). All Farkas PIs in each group showed significant differences from the golden ratio except for PI19 (upper/lower vermilion heights). CONCLUSIONS: Paraguayans favor rectangular faces with wide mouths and large lips, especially the lower lips, whereas Koreans prefer long tapered faces with small mouths and lips. All proportion indexes were significantly different from the golden ratio except for PI19. Therefore, it would be beneficial for clinicians to consider the differences in ethnic preferences in facial esthetics during diagnosis and treatment planning.

10.
J Clin Pediatr Dent ; 44(3): 202-208, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32644891

RESUMO

Objectives: The aim of study was to evaluate skeletodental and soft tissue treatment effects and the amount of maxillary molar distalization with modified C-palatal plates vs. Greenfield molar distalizer appliances in adolescents. Study design: The samples consisted of pre- and posttreatment lateral cephalograms collected from 39 patients with Class II malocclusion. The MCPP group was comprised of 21 patients (mean age: 11.7 ± 1.3 years) treated with MCPP appliances while the GMD group included 18 patients (mean age: 11.2 ± 0.9 years) treated with GMD. Fixed orthodontic treatment started with the distalization process in both groups. From each cephalograpm, twenty-nine variables were measured for analysis and then the two groups were compared. Descriptive statistics, a paired t-test, and multivariate analysis of variance were performed to compare the treatment effects within and between the groups. Results: There was significant treatmentrelated change in the sagittal position of the maxilla and the mandible within each group. However, there were no statistically significant inter-group differences. The mean maxillary first molar distalization was 3.96 mm in the MCPP group vs. 2.85 mm in the GMD group. Both groups showed minimal distal tipping, but the maxillary incisors were significantly extruded by 3.04 ± 0.89 mm (P < .001) in GMD group. There was no significant difference in treatment duration between the groups. Conclusions: The maxillary first molars of both the MCPP and GMD groups were effectively distalized and there were significant skeletal changes in the maxilla. However, the maxillary incisors were significantly extruded in the GMD group.


Assuntos
Má Oclusão de Angle Classe II , Procedimentos de Ancoragem Ortodôntica , Adolescente , Cefalometria , Criança , Humanos , Maxila , Dente Molar , Desenho de Aparelho Ortodôntico , Aparelhos Ortodônticos , Técnicas de Movimentação Dentária
11.
Korean J Orthod ; 50(2): 120-128, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32257937

RESUMO

Objective: The aims of the present study were to evaluate the changes in the maximum lip-closing force (MLF) after orthodontic treatment with or without premolar extractions and verify the correlation of these changes with dentoskeletal changes. Methods: In total, 17 women who underwent nonextraction orthodontic treatment and 15 women who underwent orthodontic treatment with extraction of all four first premolars were included in this retrospective study. For all patients, lateral cephalograms and dental models were measured before (T0) and after (T1) treatment. In addition, MLF was measured at both time points using the Lip De Cum LDC-110R® device. Statistical analyses were performed to evaluate changes in clinical variables and MLF and their correlations. Results: Both groups showed similar skeletal patterns, although the extraction group showed greater proclination of the maxillary and mandibular incisors and lip protrusion compared to the nonextraction group at T0. MLF at T0 was comparable between the two groups. The reduction in the arch width and depth and incisor retroclination from T0 to T1 were more pronounced in the extraction group than in the nonextraction group. MLF in the extraction group significantly increased during the treatment period, and this increase was significantly greater than that in the nonextraction group. The increase in MLF was found to be correlated with the increase in the interincisal angle and decrease in the intermolar width, arch depth, and incisor-mandibular plane angle. Conclusions: This study suggests that MLF increases to a greater extent during extraction orthodontic treatment than during nonextraction orthodontic treatment.

12.
Korean J Orthod ; 50(1): 52-62, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32042720

RESUMO

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.

13.
Am J Orthod Dentofacial Orthop ; 156(6): 832-839, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31784017

RESUMO

INTRODUCTION: The purpose of this study was to evaluate skeletal, dentoalveolar, and soft tissue changes at 3 years posttreatment in patients with Class II Division 1 malocclusion treated with modified C-palatal plates (MCPPs). METHODS: The sample consisted of 69 lateral cephalograms of 23 patients Class II Division 1 malocclusion (9 men, 14 women; average age, 20.1 years) who underwent bilateral distalization of their maxillary dentition. The lateral cephalograms were taken immediately before the placement of the MCPPs (T1); at the end of orthodontic fixed appliance therapy (T2); and at the posttreatment observation period (3 years posttreatment; T3). Twenty-three variables were measured. Repeated measures ANOVA followed by post hoc analysis using Bonferroni test was used to identify significant differences between time points. RESULTS: Maxillary first molars showed a distal movement of 3.44 ± 1.08 mm (P <0.001) distal crown tipping of 2.35° ± 6.74°, and intrusion of 1.42 ± 1.12 mm from T1 to T2. However, from T2 to T3, there was an average of 0.41 ± 0.25 mm of mesial movement, 0.50 ± 0.46 mm of extrusion, and insignificant mesial crown tipping (0.92° ± 2.46°; P = 0.06). The nasolabial angle increased 9.36° ± 6.04° from T1 to T2 (P <0.001) but then decreased 1.55° ± 1.54° from T2 to T3. CONCLUSIONS: MCPPs are a viable treatment option for maxillary total arch distalization with minimal changes in treatment effects 3 years posttreatment.


Assuntos
Má Oclusão de Angle Classe II , Técnicas de Movimentação Dentária , Cefalometria , Feminino , Humanos , Masculino , Má Oclusão de Angle Classe II/terapia , Maxila , Dente Molar , Desenho de Aparelho Ortodôntico , Adulto Jovem
14.
Medicina (Kaunas) ; 55(9)2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31484416

RESUMO

Background and objectives: This study investigated the morphology of the labial and palatal bony wall of the maxillary central and lateral incisors using cone-beam computed tomography (CBCT). The difference between males and females and the measurement between right and left sides were measured. Materials and Methods: Twenty participants, consisting of 11 females and 9 males having normal occlusion, were used for the analysis. The mean age was 21.9 ± 3.0 years. The thickness of the labial bony wall and palatal bony wall, perpendicular to the long axis of the root, were evaluated at 3 and 5 mm apical from the cemento-enamel junction (CEJ) and at the root apex. The available bony wall below the apex of the central and lateral incisors, and the angulation between the long axis of the tested tooth and outer surface of the labial bone were measured. Results: The mean labial bony wall thickness at the 3 and 5 mm apical from the CEJ were 1.1 ± 0.3 mm and 1.0 ± 0.4 mm for central incisors, respectively, as well as 1.2 ± 0.4 mm and 1.0 ± 0.4 mm for lateral incisors, respectively. The mean palatal bony wall thickness at 5 mm from the CEJ was above 2 mm in the central and lateral incisors. The percentage of labial bony wall thickness 2 mm or greater at the root apex in central incisors was higher than in lateral incisors (62.5% vs. 55.0%). The percentage of palatal bony wall thickness ≥2 mm at 3 mm apical from the CEJ in the central incisors was higher than in the lateral incisors (37.5% vs. 15.0%). The results on the left and right sides did not show statistically significant differences, except in the labial and palatal bony wall thickness at 3 mm from the CEJ in the lateral incisor. Generally, no significant differences were seen between males and females, but males had a significantly higher labial bony wall thickness at 3 and 5 mm from the CEJ in the central and lateral incisors when compared with females. Conclusions: This study showed that a majority of the cases of Korean participants had less than 2 mm of labial bony wall thickness at 3 and 5 mm apical from the CEJ at central and lateral incisors, and this should be kept in mind while performing dental practices, including tooth extraction or immediate implantation in anterior regions. Preoperative analysis using CBCT may be beneficial for establishing the treatment plan.


Assuntos
Perda do Osso Alveolar/classificação , Oclusão Dentária , Incisivo/patologia , Adolescente , Tomografia Computadorizada de Feixe Cônico/métodos , Feminino , Humanos , Masculino , Maxila/patologia , Adulto Jovem
16.
Korean J Orthod ; 49(4): 205-213, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31367575

RESUMO

Objective: The aim of this study was to evaluate the amount of tooth movement and histologic changes with different corticotomy designs and micro-osteoperforation in rabbits. Methods: The sample consisted of 24 rabbits divided into three experimental groups (triangular corticotomy [TC] and indentation corticotomy [IC] with flap, and flapless micro-osteoperforations [MP]) and a control. A traction force of 100 cN was applied by connecting the first premolars to the incisors. The amount of tooth movement was measured. Kruskal-Wallis test was used to assess differences in tooth movement between the groups. Micro-computed tomography, hematoxylin and eosin staining, and tartrate-resistant acidic phosphatase (TRAP) analysis were performed. Analysis of variance was applied to assess differences in TRAP-positive osteoclast count between the groups. Results: The amount of tooth movement increased by 46.5% and 32.0% in the IC and MP groups, respectively, while the bone fraction analysis showed 69.7% and 8.5% less mineralization compared to the control. There were no significant intergroup differences in the number of TRAP-positive osteoclasts. Conclusions: The micro-osteoperforation group showed no significant differences in the amount of tooth movement compared to the corticotomy groups, nor in the TRAP-positive osteoclast count compared to both corticotomy groups and control.

17.
Korean J Orthod ; 49(3): 188-193, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31149609

RESUMO

Objective: The aim of this finite element study was to clarify the mechanics of tooth movement in palatal en-masse retraction of segmented maxillary anterior teeth by using anchor screws and lever arms. Methods: A three-dimensional finite element method was used to simulate overall orthodontic tooth movements. The line of action of the force was varied by changing both the lever arm height and anchor screw position. Results: When the line of action of the force passed through the center of resistance (CR), the anterior teeth showed translation. However, when the line of action was not perpendicular to the long axis of the anterior teeth, the anterior teeth moved bodily with an unexpected intrusion even though the force was transmitted horizontally. To move the anterior teeth bodily without intrusion and extrusion, a downward force passing through the CR was necessary. When the line of action of the force passed apical to the CR, the anterior teeth tipped counterclockwise during retraction, and when the line of action of the force passed coronal to the CR, the anterior teeth tipped clockwise during retraction. Conclusions: The movement pattern of the anterior teeth changed depending on the combination of lever arm height and anchor screw position. However, this pattern may be unpredictable in clinical settings because the movement direction is not always equal to the force direction.

18.
Orthod Craniofac Res ; 22(4): 329-336, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31230415

RESUMO

OBJECTIVES: To clarify the mechanics of tooth movement in mesialization of the whole mandibular dentition when changing the force angulation. SETTING: A finite element method was used to simulate long-term movements of the whole mandibular dentition. MATERIAL AND METHODS: Tooth movement was simulated by accumulating the initial displacement, which was produced by elastic deformation of the periodontal ligament. Mesial forces of 3 N were applied to the second molar bracket at -30°, -15°, 0°, 15° and 30° to the occlusal plane. RESULTS: The whole dentition and occlusal plane were rotated depending on the direction of the force with respect to the centre of resistance (CR). At a force angulation of -30°, the line of action of the force passed near the CR, and the whole dentition translated without rotation of the occlusal plane. The second molar tipped buccally due to a clearance gap between the archwire and bracket slot. When increasing a force angulation from -30°, the line of action of the force passed above the CR, and thereby, the occlusal plane rotated clockwise. This rotation of the whole dentition induced tipping of the individual teeth. Buccal tipping of the molar due to an elastic deformation of the archwire was prevented by using a lingually pre-bent archwire. CONCLUSIONS: Careful selection of force angulation and biomechanics is essential to obtain proper tooth movement in total mesialization of the mandibular dentition.


Assuntos
Dentição , Dente , Análise de Elementos Finitos , Dente Molar , Técnicas de Movimentação Dentária
19.
Am J Orthod Dentofacial Orthop ; 155(3): 388-397, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30826042

RESUMO

INTRODUCTION: The aim of this finite element study was to analyze and clarify the mechanics of tooth movement patterns for total distalization of the mandibular dentition based on force angulation. METHODS: Long-term orthodontic movement of the mandibular dentition was simulated by accumulating the initial displacement of teeth produced by elastic deformation of the periodontal ligament. RESULTS: Displacement of each tooth was caused by movement of the whole dentition, elastic deflection of the archwire, and clearance gap between the archwire and bracket slot. The whole dentition was rotated clockwise or counterclockwise when the line of action of the force passed below or above the center of resistance. Elastic deflection of the archwire induced a lingual tipping of the anterior teeth. It became larger when increasing the magnitude of angulation. The archwire could be rotated within the clearance gap between the archwire and the bracket slot, and thereby the teeth tipped. CONCLUSIONS: Mechanics of total mandibular distalization was clarified. Selective use of force angulation with a careful biomechanical understanding can achieve proper distalization of the whole mandibular dentition.


Assuntos
Análise de Elementos Finitos , Má Oclusão de Angle Classe III/terapia , Mandíbula/fisiologia , Técnicas de Movimentação Dentária , Processo Alveolar/fisiologia , Fenômenos Biomecânicos , Módulo de Elasticidade , Humanos , Braquetes Ortodônticos , Fios Ortodônticos , Ligamento Periodontal/fisiologia
20.
Am J Orthod Dentofacial Orthop ; 155(2): 191-197, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30712690

RESUMO

INTRODUCTION: Our objectives were to evaluate changes in the position of maxillary third molars with cone-beam computed tomography images in adolescents after total arch distalization using a modified C-palatal plate (MCPP) and to compare them with the changes in a matched control group. METHODS: We included 68 maxillary third molars of 40 adolescent patients (mean age, 12.6 years). They were divided into MCPP and control groups. Cone-beam computed tomography images were taken before and after molar distalization (mean duration, 14.4 months) in the MCPP group and also in the control group (mean duration, 12.9 months). The changes in the position, angulation, and rotation of the third molars were assessed, and the volumes of maxillary tuberosity were measured. RESULTS: After distalization, the third molars moved backward (1.2 mm) and upward (0.5 mm) in the MCPP group with a significant difference (P <0.003), and they moved downward and forward in the control group. The changes in rotation and angulation were insignificant. The volumes of maxillary tuberosity increased in both groups. CONCLUSIONS: Maxillary total arch distalization caused unerupted third molars to move backward and upward, with an insignificant difference in the posttreatment volume of maxillary tuberosity. Therefore, it may be possible to perform maxillary total arch distalization in adolescents with unerupted third molars without a germectomy, at least in the short term.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Maxila/diagnóstico por imagem , Dente Serotino/diagnóstico por imagem , Técnicas de Movimentação Dentária , Adolescente , Criança , Feminino , Humanos , Masculino , Estudos Retrospectivos , Fatores de Tempo , Técnicas de Movimentação Dentária/métodos
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