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BACKGROUND: Previous clinical observational studies have suggested that orthodontic tooth movement (OTM) is related, at least partly, to the mass and/or capabilities of the masticatory muscles. OBJECTIVES: Our study aimed to examine the influence of masticatory muscle mass on the OTM in an animal experimental model in which the masseter muscle was modulated by botulinum neurotoxin type A (BTX) injection. METHODS: Eighteen Wistar rats were equally divided into two groups: BTX injection and control. BTX was injected bilaterally into the masseter muscles. Three days after the injection, the maxillary left first molars were orthodontically moved for 14 days. At the end of the experiment, micro-computed tomography was performed to evaluate the rate of OTM and bone morphometry. The masseter muscles were weighed and prepared for histological analyses. RESULTS: The masseter muscle mass in the BTX group was less than that in the control group, and histological findings showed atrophy of muscle fibres. The rate of OTM was significantly higher in the BTX group than in the control group. Furthermore, a negative correlation was detected between masseter muscle mass and OTM in the BTX group. Bone morphometry showed no difference between the control and BTX groups. CONCLUSION: Decreased masseter muscle mass was found to be closely related to an increase in the rate of OTM in rats using BTX injection to modify the masseter muscle mass. Masseter muscle mass could be a predictive factor for OTM in rats injected with BTX.
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Toxinas Botulínicas Tipo A , Músculo Masseter , Animais , Toxinas Botulínicas Tipo A/farmacologia , Músculo Masseter/diagnóstico por imagem , Músculo Masseter/patologia , Ratos , Ratos Wistar , Técnicas de Movimentação Dentária , Microtomografia por Raio-XRESUMO
Objectives: The purpose of this study was to evaluate the relationships among the volume of bone cut during corticotomy, amount of tooth movement, volume of root resorption, and volume of the resultant alveolar bone resorption after tooth movement. Methods: Ten-week-old female Wistar rats were distributed into the corticotomy groups and a control group that underwent sham corticotomy. Two experiments employing two different orthodontic forces (10 or 25g) and experimental periods (14 or 21 days) were performed. The volumes of the bone cut by corticotomy were 0.1, 1.0, and 1.7mm3 in the 25g groups, and 1.0 and 1.7mm3 in the 10g groups. Nickel-titanium closed-coil springs were set on the maxillary left first molars to induce mesial movement. After orthodontic tooth movement, the amount of tooth movement, volume of root resorption, and volume of alveolar bone resorption were measured. Results: Despite differences in the volume of bone cut among the different corticotomy groups, there were not significant differences in the amount of tooth movement and volume of root resorption between the control group and any of the corticotomy groups. However, higher volume of bone cut during corticotomy was significantly related to the decreased alveolar bone volume-in particular, to the reduced height of the alveolar bone crest after tooth movement. Conclusions: The volume of the alveolar bone cut during corticotomy does not affect tooth movement or root resorption in 10-week-old female Wistar rats; however, it may increase alveolar bone loss after tooth movement.
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Perda do Osso Alveolar/etiologia , Processo Alveolar/cirurgia , Osso Cortical/cirurgia , Reabsorção da Raiz/etiologia , Técnicas de Movimentação Dentária/métodos , Perda do Osso Alveolar/patologia , Processo Alveolar/patologia , Animais , Osso Cortical/patologia , Feminino , Dente Molar , Ratos Wistar , Técnicas de Movimentação Dentária/efeitos adversosRESUMO
Objectives: The purpose of this preliminary study was to determine the differences between planned and actual maxillary molar movements after the completion of treatment with an initial set of clear aligners including sequential maxillary molar distalization. Methods: The data records of 14 non-growing patients who completed orthodontic treatment with sequential maxillary molar distalization using clear aligners were retrospectively evaluated (n= 14, 4 males and 10 females, 33.61 ± 8.57 years). Data on planned tooth movements were obtained from ClinCheck software (ClinCheck Pro version 5.3). The amounts of actual tooth movements were obtained by performing superimposition of lateral cephalograms taken before and after treatment. The amounts of distal translation and tipping between planned and actual maxillary molar movements were compared with the paired Student's t-test. Results: The statistically significant differences between planned and actual translation movements of maxillary first and second molars were shown after completing treatment with the first series of aligners (p < 0.05). The average actual amount of molar distalization on maxillary first molars was less than the planned amount by 1.32 ± 0.42 mm. Similarly, the average actual amount of molar distalization on maxillary second molars was less than the planned amount by 1.57 ± 0.45 mm. The accuracy for molar distalization, namely, the percentage of actual distal translation to planned movement, was 40.11% for maxillary first molars and 35.39% for maxillary second molars. However, the difference between the planned and actual angulation movements was not significant (p > 0.05). Conslusions: In conclusion, the amounts of actual distal translation of maxillary molars through the utilization of clear aligners were significantly lower than planned. However, there were no statistically significant differences between the degrees of actual and planned molar angulation movement.
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Increasing demand for adult orthodontic treatment using clear aligners has highlighted challenges in bonding clear aligner attachments to various restorations. Specifically, the bond strength of clear aligner attachments to glazed monolithic zirconia has not been extensively studied. This study aims to compare the shear bond strength (SBS) and mode of failure (MOF) of conventional bonding methods versus Superbond C&B (4-META/MMA-TBB resin cement) for clear aligner attachments on glazed monolithic zirconia. Fifty sintered and glazed zirconia samples were divided into five groups and attached with clear aligner attachments: Si (silane), B (bonding agent), SiB (bonding agent and silane), SU (Superbond C&B), and SiSU (silane and Superbond C&B). SBS and MOF of these samples were analyzed. Results indicated a significant difference in bond strength among the groups. SiSU exhibited the highest bond strength, followed by SU, while B had the lowest bond strength. SEM analysis revealed that SiSU and SU predominantly exhibited mixed failure, indicating high bond strength without affecting the glazed layers of the zirconia. In contrast, B exhibited only adhesive failure at the interface, resulting in insufficient bond strength for effective orthodontic treatment. In conclusion, using 4-META/MMA-TBB resin cement provides high bond strength for clear aligner attachments on glazed zirconia with minimal material damage during debonding.
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OBJECTIVES: To determine the effect of orthodontic pressure on periodontal ligament (PDL) compression in rats and assess correlation between PDL compression and orthodontically induced root resorption (OIRR). MATERIALS AND METHODS: Eight female Wistar rats aged 10 weeks underwent surgery to place 2 mini-screws at the center of the palatal plate. 25 cN coil springs connecting the maxillary first molars and mini-screws were applied bilaterally to generate mesial force. Maxillary first molars were assigned to undergo either bodily or tipping movements. Micro-computed tomography (µCT) scans were taken on days 0, 3, 7, and 14, and histological sections were taken on day 14. OIRR was measured from histological sections, and the corresponding PDL compression ratio was quantified using µCT images. RESULTS: The PDL was compressed by approximately 76% in tipping movement and 55% in bodily movement after 3 days, and by approximately 47% in bodily and tipping movements after 7 days of orthodontic force application. The extent of OIRR in tipping movement was significantly greater than that in bodily movement. A strong positive correlation between OIRR and PDL compression ratio was observed on day 3; however, no correlation was observed on day 7. CONCLUSIONS: A strong correlation between PDL compression ratio and OIRR was observed at an early stage after the application of orthodontic force regardless of the tooth movement type (bodily or tipping), implying the importance of early stage PDL compression in the induction of OIRR.
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Reabsorção da Raiz , Ratos , Feminino , Animais , Reabsorção da Raiz/diagnóstico por imagem , Reabsorção da Raiz/etiologia , Ratos Wistar , Ligamento Periodontal/diagnóstico por imagem , Microtomografia por Raio-X/métodos , Técnicas de Movimentação Dentária/efeitos adversos , Técnicas de Movimentação Dentária/métodosRESUMO
OBJECTIVES: To investigate whether the inhibition of 12/15-lipoxygenase (12/15-LOX), one of the core enzymes of the arachidonic acid cascade, suppresses orthodontically induced root resorption (OIRR), and examine the involvement of the hyaline degeneration of periodontal ligament cells and odontoclast differentiation. MATERIALS AND METHODS: The left maxillary first molars of 10-week-old male Wistar rats were moved mesially for 14 days using a closed-coil spring (25 cN) inserted between the first molar and incisor. The rats were intraperitoneally administered with a 12/15-LOX specific inhibitor (ML-351; 0.05 mmol/kg) daily in the experimental group or vehicle (dimethyl sulfoxide) in the control group. Tooth movement was measured using microcomputed tomography on day 14. The appearance of OIRR, hyaline degeneration, osteoclasts, and odontoclasts was evaluated via histological analysis. Immunohistochemical staining for receptor-activated NF-kB ligand (RANKL) and osteoprotegerin was performed. RESULTS: OIRR observed on day 14 in the control group was strongly suppressed by ML-351 treatment. Hyaline degeneration observed on the compression side on day 3 and the appearance of osteoclasts and odontoclasts on days 3 and 14 were significantly suppressed by ML-351. RANKL expression on day 3 was significantly suppressed by ML-351. These key processes in OIRR were substantially suppressed by ML-351 treatment. CONCLUSIONS: Inhibition of 12/15-LOX reduced OIRR by suppressing hyaline degeneration and subsequent odontoclast differentiation.
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Araquidonato 12-Lipoxigenase , Araquidonato 15-Lipoxigenase , Inibidores de Lipoxigenase , Osteoclastos , Ratos Wistar , Reabsorção da Raiz , Técnicas de Movimentação Dentária , Animais , Masculino , Técnicas de Movimentação Dentária/métodos , Reabsorção da Raiz/etiologia , Reabsorção da Raiz/prevenção & controle , Reabsorção da Raiz/patologia , Ratos , Araquidonato 15-Lipoxigenase/metabolismo , Araquidonato 12-Lipoxigenase/metabolismo , Inibidores de Lipoxigenase/farmacologia , Inibidores de Lipoxigenase/uso terapêutico , Osteoclastos/efeitos dos fármacos , Microtomografia por Raio-X , Ligante RANK/metabolismo , Diferenciação Celular/efeitos dos fármacos , Ligamento Periodontal/efeitos dos fármacos , Ligamento Periodontal/patologia , Osteoprotegerina/metabolismo , Dente MolarRESUMO
OBJECTIVES: To create an orthodontic anchor screw (OAS)-loosening model and to investigate whether filling the bone hole with beta-tricalcium phosphate (ß-TCP) can fix the OAS against orthodontic force. MATERIALS AND METHODS: Bone holes with different diameters (1.6, 2.1, or 2.5 mm) were drilled in the tibias of 11-week-old male Wistar rats, and an OAS (3.0 mm in length and 1.2 mm in diameter) was inserted. After a healing period of 2 or 4 weeks, orthodontic force was applied, and the diameter of the bone hole appropriate for the loosening model was determined. Subsequently, under the loosening model, the bone hole was filled with ß-TCP, orthodontic force was applied, and movement of the OAS and surrounding tissue changes were evaluated by micro-computed tomography images and histological specimen analysis. RESULTS: The bone hole of 1.6 mm in diameter was employed as the OAS-loosening model. When ß-TCP was inserted into the bone hole, the linear distance and mesial tipping angle of the OAS movement decreased markedly. Furthermore, the values of bone morphometry significantly increased with ß-TCP filling. CONCLUSIONS: An OAS-loosening model was established in rats and demonstrated that the loosening OAS was stabilized by ß-TCP filling through bone formation. ß-TCP may be useful for fixation of a loosening OAS.
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INTRODUCTION: The effect of zoledronic acid, a potent and novel bisphosphonate, on tooth movement and orthodontically induced root resorption in osteoporotic animals systemically treated with zoledronic acid as similarly used in postmenopausal patients has not been elucidated. Therefore, this study was undertaken. METHODS: Fifteen 10-week-old female Wistar rats were divided into 3 groups: ovariectomy, ovariectomy + zoledronic acid, and control. Only the ovariectomy and ovariectomy + zoledronic acid groups underwent ovariectomies. Two weeks after the ovariectomy, zoledronic acid was administered only to the ovariectomy + zoledronic acid group. Four weeks after the ovariectomy, 25-g nickel-titanium closed-coil springs were applied to observe tooth movement and orthodontically induced root resorption. RESULTS: There were significant differences in the amounts of tooth movement and orthodontically induced root resorption between the ovariectomy and the control groups, and also between the ovariectomy and the ovariectomy + zoledronic acid groups. There was no statistically significant difference in tooth movement and orthodontically induced root resorption between the ovariectomy + zoledronic acid and the control groups. Zoledronic acid inhibited significantly more tooth movement and significantly reduced the severity of orthodontically induced root resorption in the ovariectomized rats. The ovariectomy + zoledronic acid group showed almost the same results as did the control group in both tooth movement and orthodontically induced root resorption. CONCLUSIONS: Zoledronic acid inhibits excessive orthodontic tooth movement and also reduces the risk of severe orthodontically induced root resorption in ovariectomized rats.
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Conservadores da Densidade Óssea/farmacologia , Difosfonatos/farmacologia , Imidazóis/farmacologia , Osteoporose/tratamento farmacológico , Pós-Menopausa , Reabsorção da Raiz/prevenção & controle , Técnicas de Movimentação Dentária/efeitos adversos , Animais , Modelos Animais de Doenças , Feminino , Osteoporose/complicações , Ratos , Ratos Wistar , Reabsorção da Raiz/etiologia , Ácido ZoledrônicoRESUMO
Periosteal fasciitis (PF), a subtype of nodular fasciitis, is an uncommon benign soft-tissue mass that originates from the periosteum or tissues adjacent to bones. PF has rarely seen in children, especially involving in the mandible. This case report presents a rare case of PF originating from the periosteum of the mandible in an 11-year-old girl. She was referred to our hospital with fast-growing painless swelling in her left mandible. Computed tomography revealed an exophytic juxtacortical mass eroding the lower part of the left mandible and lower mandibular cortex with a periosteal reaction. The mass showed low signal intensity on T1-weighted magnetic resonance imaging (MRI) and high signal intensity on T2-weighted MRI. The apparent diffusion coefficient (ADC) of the lesion found to be moderate. Dynamic contrast-enhanced MRI revealed a gradual increment pattern in the central region of the mass. On 18F-fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT), relatively high 18F-FDG uptake was observed on the early scan and the 18F-FDG uptake was declined on the delayed scan. The clinical and conventional radiological findings of the mass were suggestive of malignancy. However, the findings of ADC and dynamic MRI and dual-time-point FDG-PET/CT favored benign etiology over malignant etiology. Histological and immunohistochemical findings along with reactive ossification of the periosteum confirmed the diagnosis of PF. Currently, comprehensive examinations, such as clinical, imaging, and histopathological examinations, are recommended for the definitive diagnosis of PF, while MRI and dual-time-point FDG-PET/CT could have a potential usefulness to differentiate from malignancy.
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Fasciite , Neoplasias , Criança , Fasciite/diagnóstico por imagem , Fasciite/patologia , Feminino , Fluordesoxiglucose F18 , Humanos , Mandíbula/diagnóstico por imagem , Mandíbula/patologia , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Compostos RadiofarmacêuticosRESUMO
OBJECTIVES: To examine whether lithium suppresses orthodontically induced root resorption (OIRR) via two mechanisms (prevention of hyalinization in periodontal tissue and suppression of odontoclasts) and to investigate the changes in the periodontal tissue and alveolar bone, focusing on the appearance of cell death, hyalinization, and odontoclasts. MATERIALS AND METHODS: The maxillary first molars of 10-week-old male Wistar rats were moved mesially by a closed-coil spring for 14 days. Lithium chloride (LiCl; 0.64 mM/kg) or saline (control) was administered intraperitoneally daily. Tooth movements were measured using micro-computed tomography. Appearances of cell death, hyalinization, and odontoclasts were evaluated by histological analysis. RESULTS: OIRR observed on day 14 in the control group was suppressed strongly by LiCl administration. Apoptotic cells observed on day 1 in the compression area were gradually diminished on days 2 and 3 and transformed to hyalinization tissue in the control group. LiCl administration remarkably suppressed this cell death and subsequent hyalinization. Also, the appearance of odontoclasts in the compression area observed on day 7 was significantly suppressed by LiCl administration. Accordingly, these degenerative processes to OIRR were suppressed substantially by LiCl treatment. CONCLUSIONS: Lithium reduces OIRR through the suppression of periodontal ligament cell death, hyalinization, and odontoclast formation.
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Reabsorção da Raiz , Animais , Morte Celular , Lítio/metabolismo , Lítio/farmacologia , Masculino , Osteoclastos/patologia , Ratos , Ratos Wistar , Reabsorção da Raiz/etiologia , Reabsorção da Raiz/metabolismo , Reabsorção da Raiz/prevenção & controle , Técnicas de Movimentação Dentária/efeitos adversos , Técnicas de Movimentação Dentária/métodos , Microtomografia por Raio-X/métodosRESUMO
INTRODUCTION: Even though the beneficial effects of fluoride on enamel and root caries have been well documented, limited data are available concerning the effect of fluoride on orthodontically induced root resorption and tooth movement. Our objective was to investigate the effect of systemic fluoride administered from birth to 12 weeks on orthodontically induced root resorption and tooth movement in rat molars. METHODS: Fifty male Wistar rats were randomly divided into 5 groups. The negative control group received no sodium fluoride and had no tooth movement. The positive control group received no sodium fluoride but had tooth movement. Three experimental groups received sodium fluoride at 45 ppm from birth to 2, 4, and 12 weeks, respectively. At week 10, a 50-g nickel-titanium coil spring was applied to the maxillary left first molar for 2 weeks. The rats were killed at 12 weeks of age. Movement of the maxillary first molars was measured in relation to the maxillary second molar on digitized cephalometric radiographs. Mesial and distal roots were examined by using scanning electron and 3-dimensional laser microscopes. RESULTS: Fluoride reduced the depth, volume, and roughness of the resorption craters in the experimental groups. However, the area was similar to that in the positive control group. Regarding the duration of fluoride intake, the longer fluoride was administered via drinking water, the smaller the amount of tooth movement observed. CONCLUSIONS: Fluoride in drinking water from birth reduced the severity of orthodontically induced root resorption, but the amount of tooth movement was also decreased.
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Remodelação Óssea/efeitos dos fármacos , Reabsorção da Raiz/prevenção & controle , Fluoreto de Sódio/administração & dosagem , Técnicas de Movimentação Dentária , Animais , Análise do Estresse Dentário , Relação Dose-Resposta a Droga , Ingestão de Líquidos , Masculino , Distribuição Aleatória , Ratos , Ratos Wistar , Reabsorção da Raiz/etiologia , Técnicas de Movimentação Dentária/efeitos adversos , Técnicas de Movimentação Dentária/instrumentaçãoRESUMO
INTRODUCTION: Root resorption is a side effect of orthodontic treatment that occurs with the removal of hyalinized tissue. Studies have shown that a reparative process in the periodontium begins when the applied orthodontic force is discontinued or reduced below a certain level. However, quantitative 3-dimensional evaluation of root resorption repair has not been done. The aim of this study was to quantitatively assess the 2- and 3-dimensional changes of root resorption craters after 2 weeks of continuous mesially applied orthodontic forces of 50 g on rat molars and 2- to 16-week retention periods. METHODS: We used 60 male Wistar rats (10 weeks old). Nickel-titanium closed-coil springs were used to apply 50-g mesial forces for 2 weeks to move the maxillary left first molars. The rats were randomly allocated to 6 groups. Those in the zero-week retention group were killed after force application. In the remaining 5 groups, the interdental spaces between the maxillary first and second molars were filled with resin to retain the molars. The molars were extracted after periods of retention from 2 and 16 weeks. The maxillary right molars were used as the controls. Mesial and distal roots (distobuccal and distopalatal) were examined by using scanning electron and 3-dimensional scanning laser microscopes. The surface area, depth, volume, and roughness of the root resorption craters were measured. RESULTS: The area, depth, and volume of the craters decreased gradually and showed similar trends over the retention time, approaching a plateau at the 12th week. After 16 weeks of retention, the volumes of the resorption craters of the distobuccal and distopalatal roots reached recovery peaks of 69.5% and 66.7%, respectively. Small pits on the mesial roots showed recovery of 62.5% at the 12th week. The healing patterns in distal roots with severe resorption and mesial roots with shallow resorption had no significant differences. CONCLUSIONS: The resorption and repair processes during the early stages of retention are balanced, and most of the reparative process occurs after 4 weeks of passive retention after the application of orthodontic force. Frequent orthodontic reactivations should be avoided to allow recovery and repair of root surface damage.
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Imageamento Tridimensional/métodos , Dente Molar/fisiopatologia , Reabsorção da Raiz/fisiopatologia , Técnicas de Movimentação Dentária/instrumentação , Raiz Dentária/fisiopatologia , Animais , Ligas Dentárias , Cemento Dentário/fisiopatologia , Cemento Dentário/ultraestrutura , Masculino , Maxila , Microscopia Confocal/métodos , Microscopia Eletrônica de Varredura/métodos , Dente Molar/ultraestrutura , Níquel , Odontometria/métodos , Contenções Ortodônticas , Fios Ortodônticos , Distribuição Aleatória , Ratos , Ratos Wistar , Reabsorção da Raiz/patologia , Estresse Mecânico , Fatores de Tempo , Titânio , Colo do Dente/fisiopatologia , Colo do Dente/ultraestrutura , Técnicas de Movimentação Dentária/efeitos adversos , Raiz Dentária/ultraestrutura , Cicatrização/fisiologiaRESUMO
INTRODUCTION: The purpose of this study was to evaluate the efficacy of the Schwarz appliance with a new method of superimposing detailed cone-beam computed tomography (CBCT) images. METHODS: The subjects were 28 patients with Angle Class I molar relationships and crowding; they were randomly divided into 2 groups: 14 expanded and 14 nonexpanded patients. Three-dimensional Rugle CBCT software (Medic Engineering, Kyoto, Japan) was used to measure 10 reference points before treatment (T0) and during the retention period of approximately 9 months after 6 to 12 months of expansion (T1). Cephalometric and cast measurements were used to evaluate the treatments in both groups. Also, the mandibular widths of both groups were measured along an axial plane at 2 levels below the cementoenamel junction from a CBCT scan. Differences between the 2 groups at T0 and T1 were analyzed by using the Mann-Whitney U test. RESULTS: The dental arch (including tooth root apices) had expanded; however, alveolar bone expansion was only up to 2 mm below the cementoenamel junction. There was a statistically significant (P <0.05) difference between the groups in terms of crown, cementoenamel junction, root, and upper alveolar process. However, no significant (P >0.05) differences were observed in the interwidths of the mandibular body, zygomatic bones, condylar heads, or mandibular antegonial notches. In the mandibular cast measurements, arch crowding and arch perimeter showed statistically significant changes in the expanded group. The buccal mandibular width and lingual mandibular width values had significant changes as measured from a point 2 mm below the cementoenamel junction. CONCLUSIONS: The findings suggest that the Schwarz appliance primarily affected the dentoalveolar complex, but it had little effect on either the mandibular body or any associated structures. In addition, the molar center of rotation was observed to be below the root apex.
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Cefalometria/métodos , Tomografia Computadorizada de Feixe Cônico/métodos , Má Oclusão Classe I de Angle/terapia , Mandíbula/diagnóstico por imagem , Desenho de Aparelho Ortodôntico , Aparelhos Ortodônticos , Processo Alveolar/diagnóstico por imagem , Criança , Arco Dental/diagnóstico por imagem , Feminino , Seguimentos , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Masculino , Má Oclusão Classe I de Angle/diagnóstico por imagem , Côndilo Mandibular/diagnóstico por imagem , Maxila/diagnóstico por imagem , Dente Molar/diagnóstico por imagem , Técnica de Expansão Palatina , Ápice Dentário/diagnóstico por imagem , Colo do Dente/diagnóstico por imagem , Coroa do Dente/diagnóstico por imagem , Raiz Dentária/diagnóstico por imagem , Resultado do Tratamento , Zigoma/diagnóstico por imagemRESUMO
OBJECTIVE: The purpose of this research was to evaluate a new method of superimposing detailed cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: This study used 5 different software programs to transform the digital imaging and communication in medicine (DICOM) data from CBCT image into polygon data. The data conversion errors from different software programs were verified by the poly-acetal ball test and the dry skull test. The iterative closest point (ICP) method was used for precise superimposition. To evaluate changes related to growth, three different domains were superimposed in order to investigate appropriate areas for evaluation by the ICP method. RESULTS: The ICP method in the cranial base (excluding the peripheral zone) was indicated as the most reliable surface in this research. There were no measurement errors in converting the image data between software programs. CONCLUSION: The ICP method in the cranial base (excluding the peripheral zone) is one of the most accurate methods for superimposition when the mandibular rotation or displacement has not occurred during growth or treatment. This 3-dimensional (3D) superimposition technique can be used for a valid and reproducible assessment of treatment outcomes for growing subjects. This method is considered to be of clinical value because of the manageability and 3D accuracy of the data comparison with multi planar reconstruction (MPR) images.
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Cefalometria/métodos , Tomografia Computadorizada de Feixe Cônico/métodos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Desenvolvimento Maxilofacial/fisiologia , Acetais , Criança , Feminino , Humanos , Masculino , Mandíbula/anatomia & histologia , Mandíbula/diagnóstico por imagem , Côndilo Mandibular/anatomia & histologia , Côndilo Mandibular/diagnóstico por imagem , Órbita/diagnóstico por imagem , Ortodontia Corretiva , Imagens de Fantasmas , Polímeros , Crânio/anatomia & histologia , Base do Crânio/diagnóstico por imagem , Software , Resultado do TratamentoRESUMO
OBJECTIVE: To test the efficacy of an animal model of pain and stress and evaluate the effects of celecoxib administered when orthodontic force is applied. MATERIALS AND METHODS: A 20-g reciprocal force was applied via an orthodontic appliance to the maxillary left first and second molars of 7-week-old male Sprague-Dawley rats. Rat behavior was evaluated at 5, 24, and 48 hours after the appliance was set. Behavior was assessed in a test field by the number of lines crossed in the first 30 seconds and 5 minutes following force application; number of lines crossed to the center; rearing time; and facial grooming time. Experimental group 1 received intraperitoneal administration of 30 mg/kg celecoxib before every behavioral test. Experimental group 2 received 90 mg/kg before the first behavioral test, and physiologic saline was administered before the remaining behavioral tests. Control groups received saline before every behavioral test and were given passive (passive control group) and active (active control group) appliances, respectively. RESULTS: Parameters related to pain increased in the active controls, whereas the parameters in the experimental groups decreased to the level seen in the passive controls. Statistically significant differences in pain-related behavior between control and experimental groups were found at 5 and 24 hours after placing the appliance. Stress-related behavior was significantly less in the experimental groups compared to the active control group during experimental periods. CONCLUSIONS: The administration of celecoxib relieves pain- and stress-related behavior evoked by orthodontic tooth movement in the rat. This model might be a useful tool for the evaluation of pain and stress.
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Anti-Inflamatórios não Esteroides/uso terapêutico , Inibidores de Ciclo-Oxigenase 2/uso terapêutico , Dor/prevenção & controle , Pirazóis/uso terapêutico , Estresse Psicológico/prevenção & controle , Sulfonamidas/uso terapêutico , Técnicas de Movimentação Dentária/efeitos adversos , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Comportamento Animal/efeitos dos fármacos , Fenômenos Biomecânicos , Celecoxib , Inibidores de Ciclo-Oxigenase 2/administração & dosagem , Modelos Animais de Doenças , Comportamento Exploratório/efeitos dos fármacos , Asseio Animal/efeitos dos fármacos , Injeções Intraperitoneais , Masculino , Atividade Motora/efeitos dos fármacos , Fios Ortodônticos , Pré-Medicação , Pirazóis/administração & dosagem , Ratos , Ratos Sprague-Dawley , Estresse Mecânico , Sulfonamidas/administração & dosagem , Fatores de Tempo , Técnicas de Movimentação Dentária/instrumentaçãoRESUMO
OBJECTIVE: To investigate the precise longitudinal change in the periodontal ligament (PDL) space width and three-dimensional tooth movement with continuous-force magnitudes in living rats. MATERIALS AND METHODS: Using nickel-titanium closed-coil springs for 28 days, 10-, 25-, 50-, and 100-g mesial force was applied to the maxillary left first molars. Micro-CT was taken in the same rat at 0, 1, 2, 3, 10, 14, and 28 days. The width of the PDL was measured in the pressure and tension sides from 0 to 3 days. Angular and linear measurements were used to evaluate molar position at day 0, 10, 14, and 28. The finite element model (FEM) was constructed to evaluate the initial stress distribution, molar displacement, and center of rotation of the molar. RESULTS: The initial evaluation of PDL width showed no statistical differences among different force magnitudes. Tooth movement was registered 1 hour after force application and gradually increased with time. From day 10, greater tooth movement was observed when 10 g of force was applied. The FEM showed that the center of rotation in the molar is located in the center of five roots at the apical third of the molar roots. CONCLUSION: The rat's molar movement mainly consists of mesial tipping, extrusion of distal roots, intrusion of mesial root, palatal inclination, and mesial rotation. Although the initial tooth movement after the application of different force magnitudes until day 3 was not remarkably different, 10 g of force produced more tooth movement compared with heavier forces at day 28.
Assuntos
Análise do Estresse Dentário , Ligamento Periodontal/fisiologia , Técnicas de Movimentação Dentária , Raiz Dentária/fisiologia , Animais , Análise do Estresse Dentário/métodos , Análise de Elementos Finitos , Imageamento Tridimensional , Masculino , Dente Molar/fisiologia , Ligamento Periodontal/diagnóstico por imagem , Ratos , Ratos Wistar , Microtomografia por Raio-X/métodosRESUMO
OBJECTIVE: To test the hypothesis that the administration of aspirin, acetaminophen, meloxicam, celecoxib, and prednisolone have no effect on root resorption and tooth movement. MATERIALS AND METHODS: A mesial force of 50 g was applied to the left maxillary first molars of sixty 10-week-old male Wistar rats using nickel titanium closed coil springs attached to the cervical area of the incisors. The rats were randomly divided into 12 groups of 5 each. High and low doses of aspirin, acetaminophen, meloxicam, celecoxib, and prednisolone were administered via drinking water for 2 weeks. The experimental control group had tooth movement but received no drug. The negative control group received neither tooth movement nor drugs. The amount of tooth movement was measured on digitized lateral cephalometric radiographs. Rats were sacrificed after 2 weeks. Mesial and distal roots (distobuccal and distopalatal) were examined using scanning electron and three-dimensional (3D) scanning laser microscopes. The surface area, depth, volume, and roughness of the root resorption craters were measured. RESULTS: When compared with experimental control rats, only prednisolone- and high-dose celecoxib-treated groups showed significantly less root resorption and less tooth movement. Although low dose celecoxib-treated group significantly decreased the tooth movement, root resorption was similar to the control group. Furthermore, resorption craters showed a smoother surface in the prednisolone-treated rats. CONCLUSIONS: The hypothesis was rejected. Administration of prednisolone and high-dose celecoxib reduces root resorption and interferes with tooth movement in rats. Both drugs may interfere in the arachidonic acid cascade depending on dose thresholds.
Assuntos
Anti-Inflamatórios não Esteroides/administração & dosagem , Glucocorticoides/administração & dosagem , Reabsorção da Raiz/prevenção & controle , Técnicas de Movimentação Dentária , Animais , Cefalometria , Inibidores de Ciclo-Oxigenase/administração & dosagem , Relação Dose-Resposta a Droga , Masculino , Distribuição Aleatória , Ratos , Ratos WistarRESUMO
OBJECTIVE: To investigate by behavioral methods the relationship between emotional stress and pain during experimental tooth movement in rats. MATERIALS AND METHODS: Sixteen male Sprague-Dawley rats (210 to 250 g) were divided into two groups. The experimental group was treated with an active Ti-Ni appliance, and the control group received a passive appliance. A force of 20 gf was delivered by the active appliance between the maxillary first and second molars for 3 days. During this period the rat's behavior was evaluated eight times by means of open-field test and resistance-to-capture test. The specific parameters of animal activity were facial grooming, rearing, and locomotor activity, movement into the center of the open field, and response to capture. RESULTS: Parameters related to stress and pain were higher in the group carrying active appliance, compared to the group with a passive appliance. Statistically significant differences in stress-related behavior between control and experimental groups were found 8 hours after placing the appliance and were most evident on the second day. Pain-related behavior was significantly greater in the experimental group than in the control group at 24 hours. CONCLUSIONS: The increase in emotional stress evoked by orthodontic tooth movement may precede the appearance of periodontal pain.
Assuntos
Comportamento Animal/fisiologia , Dor/psicologia , Estresse Psicológico/psicologia , Técnicas de Movimentação Dentária/instrumentação , Animais , Ligas Dentárias , Reação de Fuga/fisiologia , Comportamento Exploratório/fisiologia , Asseio Animal/fisiologia , Locomoção/fisiologia , Masculino , Níquel , Desenho de Aparelho Ortodôntico , Fios Ortodônticos , Dor/fisiopatologia , Ratos , Ratos Sprague-Dawley , Estresse Mecânico , Estresse Psicológico/fisiopatologia , Fatores de Tempo , Titânio , Técnicas de Movimentação Dentária/psicologiaRESUMO
OBJECTIVE: To test the hypothesis that there is no difference in the effect of different continuous moderate to very heavy forces on root resorption or amount of tooth movement. MATERIALS AND METHODS: In the study, 10, 25, 50 and 100 g mesial force were applied to the maxillary first molars of rat using nickel titanium closed-coil springs for 3 days, 14 days, and 28 days. The molars were extracted and the surface areas of the root resorption craters were measured using scanning electron microscope. The depths of the root resorption craters were measured using a three-dimensional laser scanning microscope. Tooth movement of the maxillary first molar was measured in relation to the maxillary second molar on digitized lateral cephalometric radiographs. RESULTS: Three days after force application, the tooth movement was not proportionally related to force magnitude. However, 14 days of force application resulted in significantly more tooth movement in the 10, 25, and 50 g force groups than in the 100 g force group. A force application of 10 g produced significantly more tooth movement at 28 days than all the other three force applications. The largest and deepest resorption craters were observed in the disto-buccal root followed by disto-palatal, middle-buccal, middle-palatal, and mesial root. Root resorption and tooth movement increased over time from 3 to 28 days. As heavier forces were applied, greater root resorption occurred. CONCLUSION: The hypothesis is rejected. The light mesially oriented forces, as applied in this study, produced more tooth movement and less root resorption compared with heavier forces.
Assuntos
Dente Molar/patologia , Reabsorção da Raiz/etiologia , Técnicas de Movimentação Dentária/métodos , Animais , Cefalometria/métodos , Ligas Dentárias , Cemento Dentário/patologia , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Masculino , Maxila , Microscopia Confocal/métodos , Microscopia Eletrônica de Varredura , Níquel , Fios Ortodônticos , Ratos , Ratos Wistar , Reabsorção da Raiz/patologia , Estresse Mecânico , Fatores de Tempo , Titânio , Técnicas de Movimentação Dentária/efeitos adversos , Raiz Dentária/patologiaRESUMO
OBJECTIVE: To investigate the influence of lithium chloride (LiCl) on orthodontic tooth movement (OTM), orthodontically induced root resorption (OIRR), and bone morphometry. MATERIALS AND METHODS: Ten-week-old female Sprague Dawley rats (n = 32) were divided into four groups based on the concentration of LiCl administered daily per kilogram body weight: 0 (control group), 0.32, 0.64, and 1.28 mM/kg body weight. The maxillary left first molars were moved mesially by a 10 cN coil spring for 14 days. Micro-computed tomography, scanning electron microscope, and scanning laser microscope images were taken to measure the amount of OTM, the volume of OIRR, and bone morphometry. RESULTS: OIRR clearly decreased depending on the amount of LiCl administered, although OTM moderately decreased. The tooth inclined mesially and the root apex moved distally in the control and 0.32 mM groups. On the other hand, the tooth inclination angle became smaller and the root apex moved mesially in the 0.64 and 1.28 mM groups. In bone morphometry, the cortical bone mineral content and bone volume increased because of LiCl administration, and the trabecular bone measurements decreased. OIRR negatively correlated to the cortical bone measurements, and the amount of OTM significantly correlated to the cortical bone morphometry. CONCLUSIONS: In rats, LiCl reduced OIRR, which induced mesial movement of the tooth root apex. OIRR positively correlated to cortical bone morphometry.