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INTRODUCTION: The orthodontic correction of periodontally compromised dentitions constitutes a huge challenge in the clinical practice of adult orthodontics. The biological and physical distinct features of these conditions require a carefully designed mechanical plan for the successful treatment of these complex cases. SETTING AND SAMPLE POPULATION: A segment of a human maxilla containing the central and lateral incisors, obtained from autopsy, was scanned with microcomputed tomography, and a finite element (FE) model was generated to represent an intact periodontal dentition. Based on this model, three additional models simulating a mild, moderate and severe bone alveolar loss were created as well. MATERIALS AND METHODS: Two loading scenarios for the application of intrusive and retraction mechanics with a three-piece base arch appliance were evaluated in a series of FE analyses. The tooth displacements and strains in the periodontal ligament (PDL) were calculated and compared for the four FE models. RESULTS: The periodontal reduced dentitions exhibited a similar axis of resistance for intrusive mechanics, but the axis of resistance for retraction movements was significantly dependent on the degree of alveolar bone loss. The tooth displacements and PDL loads were higher in the reduced dentitions for both intrusive and retraction mechanics. CONCLUSIONS: A reduction in the force levels applied to periodontal reduced dentitions is indicated, and a customized selection of appropriate points of force application is needed according to the specific amount of alveolar bone loss.
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Incisivo , Técnicas de Movimiento Dental , Adulto , Fenómenos Biomecánicos , Simulación por Computador , Análisis de Elementos Finitos , Humanos , Maxilar/diagnóstico por imagen , Modelos Biológicos , Ligamento Periodontal/diagnóstico por imagen , Estrés Mecánico , Microtomografía por Rayos XRESUMEN
INTRODUCTION: In addition to their cholesterol-lowering effects, the statin class of drugs appears to enhance osteogenesis and suppress bone resorption, which could be a clinical concern during orthodontic treatment. In this animal study, we aimed to determine whether atorvastatin (ATV) affects orthodontic tooth movement (OTM) through osteoclast inhibition. Furthermore, we analyzed the potential adverse effects of ATV on long-bone turnover and endochondral ossification. METHODS: Rats were administered ATV (15 mg/kg) or saline solution via gavage (n = 12 animals/group), starting 2 weeks before initial OTM. Tooth displacement was measured after 7, 14, and 21 days. Histologic sections of the maxilla and femur were obtained after 14 and 21 days of OTM and stained (hematoxylin and eosin; TRAP assay) for histomorphometric analysis. RESULTS: ATV was associated with significant (P <0.05) reductions in OTM and osteoclast counts. Independently of drug administration, OTM increased the number of osteoclasts and reduced the bone-volume ratio compared with the control maxillae without OTM. Long-term statin administration did not appear to affect femoral endochondral ossification. CONCLUSIONS: This experimental study showed that the long-term use of ATV can significantly promote osteoclast inhibition and slow the OTM in the first week in rats. Under physiologic conditions, the drug did not affect bone turnover and endochondral ossification.
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Atorvastatina/farmacología , Osteogénesis/efectos de los fármacos , Técnicas de Movimiento Dental , Animales , Atorvastatina/efectos adversos , Remodelación Ósea/efectos de los fármacos , Masculino , Ratas , Ratas WistarRESUMEN
OBJECTIVE:: To investigate the masticatory and swallowing performances in patients with malocclusions before and after orthodontic treatment, comparing them to an age- and gender-matched control group with normal occlusion. METHODS:: Twenty-three patients with malocclusions requiring orthodontic treatment were included in this prospective study. One month after appliance removal, seventeen patients completed a follow-up examination and the data were compared with those of a control group with thirty subjects with normal occlusion. Masticatory performance was determined by the median particle size for the Optocal Plus® test food after 15 chewing strokes, and three variables related to swallowing were assessed: a) time and b) number of strokes needed to prepare the test-food for swallowing, and c) median particle size of the crushed particles at the moment of swallowing. RESULTS:: At the baseline examination, the malocclusion group had a significantly lower masticatory performance and did not reach the particle size reduction at the moment of swallowing, when compared with the control group. After treatment, the masticatory performance significantly improved in the malocclusion group and the particle size reduction at swallowing reached the same level as in the control group. CONCLUSIONS:: The present results showed that the correction of malocclusions with fixed appliances can objectively provide positive effects in both mastication and deglutition processes, reinforcing that besides aesthetic reasons, there are also functional indications for orthodontic treatment.
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Deglución/fisiología , Maloclusión/terapia , Masticación/fisiología , Ortodoncia Correctiva , Femenino , Humanos , Estudios Longitudinales , Masculino , Estudios Prospectivos , Resultado del Tratamiento , Adulto JovenRESUMEN
ABSTRACT Objective: To investigate the masticatory and swallowing performances in patients with malocclusions before and after orthodontic treatment, comparing them to an age- and gender-matched control group with normal occlusion. Methods: Twenty-three patients with malocclusions requiring orthodontic treatment were included in this prospective study. One month after appliance removal, seventeen patients completed a follow-up examination and the data were compared with those of a control group with thirty subjects with normal occlusion. Masticatory performance was determined by the median particle size for the Optocal Plus® test food after 15 chewing strokes, and three variables related to swallowing were assessed: a) time and b) number of strokes needed to prepare the test-food for swallowing, and c) median particle size of the crushed particles at the moment of swallowing. Results: At the baseline examination, the malocclusion group had a significantly lower masticatory performance and did not reach the particle size reduction at the moment of swallowing, when compared with the control group. After treatment, the masticatory performance significantly improved in the malocclusion group and the particle size reduction at swallowing reached the same level as in the control group. Conclusions: The present results showed that the correction of malocclusions with fixed appliances can objectively provide positive effects in both mastication and deglutition processes, reinforcing that besides aesthetic reasons, there are also functional indications for orthodontic treatment.
RESUMO Objetivo: investigar as performances mastigatória e de deglutição em pacientes com má oclusão, antes e após o tratamento ortodôntico, comparando-os com um grupo controle com oclusão normal, equiparado por idade e sexo. Métodos: vinte e três pacientes com má oclusão requerendo tratamento ortodôntico foram incluídos neste estudo prospectivo. Um mês após a remoção dos aparelhos, dezessete pacientes completaram os exames de acompanhamento, e seus dados foram comparados com aqueles de um grupo controle com trinta indivíduos com oclusão normal. A performance mastigatória foi determinada pelo tamanho mediano das partículas do alimento teste Optocal Plus® após 15 ciclos mastigatórios, e três variáveis relacionadas à deglutição foram avaliadas: a) tempo e b) número de ciclos necessários para preparar o alimento teste para deglutição, e c) tamanho mediano das partículas trituradas no momento da deglutição. Resultados: no exame inicial, o grupo com má oclusão apresentou uma menor performance mastigatória e não atingiu a redução do tamanho das partículas no momento da deglutição, quando comparado com o grupo controle. Após o tratamento, a performance mastigatória aumentou significativamente no grupo com má oclusão, e a redução do tamanho das partículas no momento da deglutição atingiu o mesmo nível do grupo controle. Conclusões: os resultados demonstraram que a correção das más oclusões com aparelhos fixos pode, objetivamente, proporcionar efeitos positivos nos processos de mastigação e deglutição, reforçando que, além de razões estéticas, existem também indicações funcionais para o tratamento ortodôntico.
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Humanos , Masculino , Femenino , Adulto Joven , Ortodoncia Correctiva , Deglución/fisiología , Maloclusión/terapia , Masticación/fisiología , Estudios Prospectivos , Estudios Longitudinales , Resultado del TratamientoRESUMEN
The present study aimed to compare the main objective parameters of mastication among individuals with different body mass indexes. One hundred and sixty participants matched for gender and age were divided in the following groups according to their body mass index (BMI): Obese group (30 ≤ BMI < 35), Overweight group (25 ≤ BMI < 30), normal range group (18.5 ≤ BMI < 25) and underweight group (17 ≤ BMI < 18.5). Each group was composed by forty subjects. The maximum bite force, the masticatory performance, chewing rate and three variables related to swallowing (number of chewing cycles, chewing time, and median particle size) were assessed in all groups. The oral conditions, including the number of teeth, number of occlusal units and salivary flow (unstimulated and stimulated) were also evaluated. Regardless of the BMI, males had a larger bite force and better masticatory and swallowing performances than females. They also chewed faster than females. Individuals of the obese group had the largest median particles sizes (both after 20 chewing cycles and at the moment of swallowing), which indicates a less good masticatory performance. The median particle sizes were negatively correlated with the number of teeth and number of occlusal units in the obese group. We did not observe large differences in masticatory performance and swallowing variables among the four weight groups, although there was a tendency that individuals of the obese group swallowed larger particles. The results of this study do not support the existence of an "obese chewing style".
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Peso Corporal , Deglución/fisiología , Conducta Alimentaria/fisiología , Masticación/fisiología , Obesidad/fisiopatología , Adolescente , Adulto , Fuerza de la Mordida , Índice de Masa Corporal , Peso Corporal/fisiología , Femenino , Humanos , Masculino , Saliva/metabolismo , Caracteres Sexuales , Factores de Tiempo , Adulto JovenRESUMEN
Objetivo avaliar o dimorfismo sexual e a relação entre as características morfológicas craniofaciais, dos arcos dentários e do músculo masseter na fase de dentição mista. Métodos 32 crianças, com idade entre 6-10 anos (14♀/18♂) com oclusão normal, compuseram a amostra. Características morfológicas craniofaciais, dos arcos dentários e espessura do masseter foram avaliadas por meio de radiografia cefalométrica posteroanterior, modelos em gesso e ultrassonografia, respectivamente. Os resultados foram analisados utilizando testes Shapiro-Wilk, Mann-Whitney/teste “t” e regressão linear múltipla para avaliar a relação entre a largura da face e idade, gênero, índice de massa corporal, espessura do masseter, distâncias intermolares e intercaninos (entre cúspides e pontos cervicais) e larguras nasal, maxilar, mandibular e intermolar. Resultados a espessura do masseter não diferiu significativamente entre os lados esquerdo e direito. A comparação entre os gêneros mostrou diferença significativa apenas na largura da face (maior em meninos). O modelo de regressão mostrou que a largura da face relacionou-se positivamente com o índice de massa corporal, espessura do masseter, distâncias intermolares (cúspides) e intercaninos (cervicais) inferiores e largura intermolar maxilar; e negativamente com a distância intermolares superiores (cúspides) e inferiores (cervicais) e intercaninos inferiores (cervicais). Ou seja, quando as demais variáveis foram adicionadas ao modelo, a variável explanatória gênero não alcançou valor significativo. Conclusão na amostra avaliada, a espessura do masseter e dimensões dos arcos dentários não diferiram entre gêneros; além disso, a largura da face mostrou relação ...
Purpose to evaluate sexual dimorphism and the relationship between craniofacial characteristics, dental arch morphology and masseter muscle thickness in children in the mixed dentition stage. Methods the study sample comprised 32 children, aged 6-10 years (14♀/18♂) with normal occlusion. Craniofacial characteristics, dental morphology and masseter muscle thickness were evaluated by means of posteroanterior cephalometric radiographs, dental cast evaluation and ultrasound exam, respectively. The results were analyzed using Shapiro-Wilk test, Mann-Whitney/t-test and stepwise linear regression to assess the relation between face width and age, gender, body mass index, masseter thickness, distances between first molars and canines on dental casts (between cusps/cervical points), nasal, maxillary, mandibular and intermolar widths. Results masseter thickness showed no significant difference between the sides left/right. The comparison between genders showed significant difference only in face width, being larger in boys. The regression model showed that face width was positively related with body mass index, masseter thickness, mandibular first molar distances (cusps), mandibular canine distances (cervical points), and maxillary intermolar width; and negatively with maxillary (cusps) and mandibular molar distances (cervical points) and mandibular canine distances (cusps). That is, when the other studied variables were considered, the explanatory variable gender did not reach a significant value. Conclusion in the studied sample, the dimensions of the dental arches and masseter thickness did not differ between boys and girls; moreover, face width showed significant relationship with body mass index, masseter thickness, and dimensions of dental arches; but gender did not contribute significantly to face width variation. .
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OBJECTIVE: The aim of this study was to assess pain, masticatory performance and swallowing threshold of patients undergoing orthodontic treatment. METHODS: Ten patients of both genders (mean age of 17.25 ± 5.21 years), with complete permanent dentition, who underwent orthodontic treatment with fixed appliances were evaluated. The masticatory performance and the swallowing threshold were assessed by patient's individual capacity of fragmenting an artificial test food (Optocal) which was chewed and had the resulting particles processed by a standardized sieving method, presenting the median particle size (MPS) of crushed units. The intensity of pain / discomfort during chewing was evaluated by means of a visual analog scale. All tests were performed at the following times: T0 - before activating the orthodontic appliance; T1 - 24 hours after activation, and T2 - 30 days after activation. RESULTS: The results showed a significant increase in pain at T1 (T0 = 0.60 ± 0.70 mm; T1 = 66.2 ± 34.5 mm), returning to baseline values at T2 (3.20 ± 3.82 mm). Masticatory performance was also reduced in T1 (MPS = 10.15 ± 1.1 mm2) in comparison to T0 (MPS 7.01 ± 2.9 mm2) and T2 (MPS 6.76 ± 1.3 mm2). However, particle size was not affected in the swallowing threshold test (T0 = 5.47 ± 2.37 mm2; T1 = 6.19 ± 2.05 mm2; T2 = 5.94 ± 2.36 mm2). CONCLUSIONS: The orthodontic appliances did not interfere in the size of the particles that would be swallowed, even in the presence of pain.
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Deglución/fisiología , Masticación/fisiología , Aparatos Ortodóncicos , Dimensión del Dolor , Adolescente , Aleaciones Dentales/química , Elastómeros/química , Femenino , Estudios de Seguimiento , Humanos , Masculino , Níquel/química , Alambres para Ortodoncia , Dolor/fisiopatología , Tamaño de la Partícula , Umbral Sensorial/fisiología , Acero Inoxidable/química , Factores de Tiempo , Titanio/químicaRESUMEN
OBJECTIVE: The aim of this study was to assess pain, masticatory performance and swallowing threshold of patients undergoing orthodontic treatment. METHODS: Ten patients of both genders (mean age of 17.25 ± 5.21 years), with complete permanent dentition, who underwent orthodontic treatment with fixed appliances were evaluated. The masticatory performance and the swallowing threshold were assessed by patient's individual capacity of fragmenting an artificial test food (Optocal) which was chewed and had the resulting particles processed by a standardized sieving method, presenting the median particle size (MPS) of crushed units. The intensity of pain / discomfort during chewing was evaluated by means of a visual analog scale. All tests were performed at the following times: T0 - before activating the orthodontic appliance; T1 - 24 hours after activation, and T2 - 30 days after activation. RESULTS: The results showed a significant increase in pain at T1 (T0 - 0.60 ± 0.70 mm; T1 - 66.2 ± 34.5 mm), returning to baseline values at T2 (3.20 ± 3.82 mm). Masticatory performance was also reduced in T1 (MPS 10.15 ± 1.1 mm²) in comparison to T0 (MPS 7.01 ± 2.9 mm²) and T2 (MPS 6.76 ± 1.3 mm²). However, particle size was not affected in the swallowing threshold test (T0 - 5.47 ± 2.37 mm²; T1 - 6.19 ± 2.05 mm²; T2 - 5.94 ± 2.36 mm²). CONCLUSION: The orthodontic appliances did not interfere in the size of the particles that would be swallowed, even in the presence of pain.
OBJETIVO: o objetivo desse estudo foi avaliar a dor, a performance mastigatória e o limiar de deglutição em pacientes submetidos ao tratamento ortodôntico. MÉTODOS: foram avaliados dez pacientes de ambos os sexos (idade média 17,25 ± 5,21 anos), com dentição permanente completa, submetidos ao tratamento ortodôntico com aparelhos fixos. A performance mastigatória e o limiar de deglutição foram avaliados pela capacidade individual de fragmentação de um alimento teste artificial (Optocal), o qual foi mastigado e as partículas resultantes processadas por um método padronizado com peneiras, apresentando o tamanho mediano das partículas (TMP) das unidades trituradas. A intensidade da dor/desconforto foi avaliada com o uso de uma escala analógica visual. Todos os testes foram realizados nos seguintes momentos: T0: antes da ativação do aparelho ortodôntico; T1: 24 após a ativação, e T2: 30 dias após a ativação. RESULTADOS: os resultados demonstraram um aumento significativo na dor em T1 (T0: 0,60 ± 0,70mm; T1: 66,2 ± 34,5mm), retornando aos valores basais em T2 (3,20 ± 3,82mm). A performance mastigatória também foi reduzida em T1 (TMP: 10,15 ± 1,1mm²) comparada a T0 (TMP: 7,01 ± 2,9mm²) e T2 (TMP = 6,76 ± 1,3 mm²). Entretanto, o tamanho das partículas não foi afetado no teste do limiar de deglutição (T0: 5,47 ± 2,37mm²; T1: 6,19 ± 2,05mm²; T2: 5,94 ± 2,36mm²). CONCLUSÃO: os aparelhos ortodônticos não interferiram no tamanho das partículas que seriam deglutidas, mesmo na presença da dor.
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Adolescente , Femenino , Humanos , Masculino , Deglución/fisiología , Masticación/fisiología , Aparatos Ortodóncicos , Dimensión del Dolor , Aleaciones Dentales/química , Elastómeros/química , Estudios de Seguimiento , Níquel/química , Alambres para Ortodoncia , Tamaño de la Partícula , Dolor/fisiopatología , Umbral Sensorial/fisiología , Acero Inoxidable/química , Factores de Tiempo , Titanio/químicaRESUMEN
The aim of this study was to detect possible differences in the EMG (electromyography) activity, chewing rate (CR), cycle duration (CD) and preferred chewing side (PCS) between children with and without unilateral posterior crossbite. Thirty-seven children aged from 7 to 10 years were selected from the clinic of the Department of Pediatric Dentistry, Piracicaba Dental School, Brazil, and divided into two groups: unilateral posterior crossbite (UPCB group, n = 17), and normal occlusion (NOccl group, n = 20). The PCS was determined using a visual spot-checking method. The EMG activity was recorded during mastication, and two chewing sequences of 20 s were evaluated to establish each subject's CR (cycles/sec) and CD. UPCB and NOccl groups did not have a PCS. The EMG activity and the cycle characteristics did not differ between the groups. The correlations between CD, CR and EMG activity were statistically significant for the masseter and anterior temporalis muscles only in the NOccl group, in which there was also a significant correlation between the EMG activity of masseter and anterior temporalis. In conclusion, these findings suggest that although children with and without UPCB presented a bilateral masticatory pattern with similar CR and CD, balanced EMG activity of masseter and anterior temporalis muscles was observed only in the NOccl group. These results indicate that in children, UPCB can alter the coordination of masticatory muscles during mastication.
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Maloclusión/fisiopatología , Masticación/fisiología , Músculos Masticadores/fisiología , Niño , Electromiografía , Lateralidad Funcional/fisiología , Humanos , Músculo Masetero/fisiología , Músculo Temporal/fisiologíaRESUMEN
OBJECTIVE: To systematically review the relationship between malocclusions and masticatory performance. In addition, we will perform a qualitative analysis of the methodological soundness of the studies. MATERIALS AND METHODS: A literature survey was done by applying the Medline database ( www.ncbi.nim.nih.gov ) in the period from January 1965 to June 2009, using the "Medical Subject Headings" term malocclusion crossed with various combinations of the following terms: masticatory performance, masticatory efficiency, and chewing efficiency. The articles were separated into two main topics: (1) the influence of malocclusion treatment (orthognathic surgery) and (2) the influence of malocclusion type and severity. RESULTS: The search strategy used identified 78 articles. After selection according to the inclusion/exclusion criteria, 12 articles qualified for the final analysis. The research quality and methodological soundness were high in one study, medium in 10 studies, and low in one study. The most serious shortcomings comprised the clinical trials and controlled clinical trials designs with small sample sizes and inadequate description of selection criteria. Lack of method error analysis and the absence of blinding in measurements were other examples of shortcomings. CONCLUSIONS: Malocclusions cause decreased masticatory performance, especially as it relates to reduced occlusal contacts area. The influence of malocclusion treatment (orthognathic surgery) on masticatory performance is only measurable 5 years after treatment.
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Maloclusión/fisiopatología , Masticación/fisiología , Ensayos Clínicos como Asunto , Ensayos Clínicos Controlados como Asunto , Humanos , Maloclusión/clasificación , Maloclusión/cirugía , Procedimientos Quirúrgicos OrtognáticosRESUMEN
The aim of this study was to detect possible differences in the EMG (electromiography) activity, chewing rate (CR), cycle duration (CD) and preferred chewing side (PCS) between children with and without unilateral posterior crossbite. Thirty-seven children aged from 7 to 10 years were selected from the clinic of the Department of Pediatric Dentistry, Piracicaba Dental School, Brazil, and divided into two groups: unilateral posterior crossbite (UPCB group, n = 17), and normal occlusion (NOccl group, n = 20). The PCS was determined using a visual spot-checking method. The EMG activity was recorded during mastication, and two chewing sequences of 20 s were evaluated to establish each subject's CR (cycles/sec) and CD. UPCB and NOccl groups did not have a PCS. The EMG activity and the cycle characteristics did not differ between the groups. The correlations between CD, CR and EMG activity were statistically significant for the masseter and anterior temporalis muscles only in the NOccl group, in which there was also a significant correlation between the EMG activity of masseter and anterior temporalis. In conclusion, these findings suggest that although children with and without UPCB presented a bilateral masticatory pattern with similar CR and CD, balanced EMG activity of masseter and anterior temporalis muscles was observed only in the NOccl group. These results indicate that in children, UPCB can alter the coordination of masticatory muscles during mastication.
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Niño , Humanos , Maloclusión/fisiopatología , Masticación/fisiología , Músculos Masticadores/fisiología , Electromiografía , Lateralidad Funcional/fisiología , Músculo Masetero/fisiología , Músculo Temporal/fisiologíaRESUMEN
The temporomandibular joint (TMJ) formalin test was used to evaluate the effects of acute restraint stress on the nociceptive behavioral responses of female rats during proestrus and estrus phases of the estrous cycle. Rats were subjected to one session of restraint stress (15, 30 min or 1 h). They were then either immediately killed to allow the collection of blood for hormonal radioimmunoassay determinations or subjected to TMJ formalin test to evaluate nociception. All stress protocols significantly raised the plasma concentrations of corticosterone. The performance of rats subjected to 15 and 30 min of restraint stress was similar to that of control rats, whereas rats that were stressed for 1 h showed a decrease in nociceptive responses, during both proestrus and estrus phases. The stress-induced analgesia (SIA) was greater in the proestrus phase. To evaluate the role of kappa-opioid receptors, the selective receptor kappa-opioid antagonist nor-binaltorphimine (nor-BNI; 200 microg or saline) was injected into the TMJ 24 h prior to the 1 h stress period and the TMJ formalin test. The local administration of nor-BNI partially reversed the SIA during the proestrus phase. These findings suggest that (1) acute stress for 1 h can produce analgesia both during proestrus and estrus phases; this effect is greater during the proestrus phase and (2) kappa-opioid receptor activation is involved in the SIA observed in the proestrus phase.
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Nociceptores/fisiología , Dimensión del Dolor , Dolor/fisiopatología , Estrés Fisiológico/fisiología , Trastornos de la Articulación Temporomandibular/fisiopatología , Enfermedad Aguda , Animales , Conducta Animal/efectos de los fármacos , Conducta Animal/fisiología , Estro/fisiología , Femenino , Formaldehído/farmacología , Naltrexona/análogos & derivados , Naltrexona/farmacología , Antagonistas de Narcóticos/farmacología , Nociceptores/efectos de los fármacos , Dolor/inducido químicamente , Proestro/fisiología , Ratas , Ratas Wistar , Receptores Opioides/fisiología , Restricción Física , Articulación Temporomandibular/efectos de los fármacos , Articulación Temporomandibular/fisiología , Trastornos de la Articulación Temporomandibular/inducido químicamenteRESUMEN
The aim of this study was to compare the mandibular size in boys and girls with Class I and Class II skeletal patterns, taking into consideration the bone maturation stage, as defined by the cervical vertebrae maturation. One hundred and sixty cephalometric radiographs were obtained from subjects (aged between 7 and 12 years) with Class I or Class II skeletal patterns, according to the ANB angle and WITS appraisal. The Class I sample consisted of 80 subjects (40 boys, 40 girls). The Class II sample also consisted of 80 subjects (40 boys, 40 girls). On a cross-sectional basis, mandibular length (Co-Gn) was compared between groups and genders. The between-stages changes were also evaluated, with the cervical vertebrae analysis used for establishing the bone maturation stages at CS2, CS3, CS4 and CS5. The results were statistically analyzed by the Kruskal-Wallis test. The mandibular length differed between skeletal patterns only at the earlier stages of development. In the Class I pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS4 and CS5, whereas in the Class II pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS3 and CS4. The present results indicate a sexual dimorphism in the mandibular length at almost all stages of bone maturation, in exception of the CS5 stage in Class II.
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Vértebras Cervicales/crecimiento & desarrollo , Maloclusión Clase II de Angle/diagnóstico por imagen , Maloclusión Clase I de Angle/diagnóstico por imagen , Mandíbula/anatomía & histología , Desarrollo Maxilofacial , Cefalometría , Niño , Estudios Transversales , Femenino , Humanos , Masculino , Tamaño de los Órganos , Radiografía , Factores Sexuales , Estadísticas no ParamétricasRESUMEN
The aim of this study was to compare the mandibular size in boys and girls with Class I and Class II skeletal patterns, taking into consideration the bone maturation stage, as defined by the cervical vertebrae maturation. One hundred and sixty cephalometric radiographs were obtained from subjects (aged between 7 and 12 years) with Class I or Class II skeletal patterns, according to the ANB angle and WITS appraisal. The Class I sample consisted of 80 subjects (40 boys, 40 girls). The Class II sample also consisted of 80 subjects (40 boys, 40 girls). On a cross-sectional basis, mandibular length (Co-Gn) was compared between groups and genders. The between-stages changes were also evaluated, with the cervical vertebrae analysis used for establishing the bone maturation stages at CS2, CS3, CS4 and CS5. The results were statistically analyzed by the Kruskal-Wallis test. The mandibular length differed between skeletal patterns only at the earlier stages of development. In the Class I pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS4 and CS5, whereas in the Class II pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS3 and CS4. The present results indicate a sexual dimorphism in the mandibular length at almost all stages of bone maturation, in exception of the CS5 stage in Class II.
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Niño , Femenino , Humanos , Masculino , Vértebras Cervicales/crecimiento & desarrollo , Desarrollo Maxilofacial , Maloclusión Clase I de Angle , Maloclusión Clase II de Angle , Mandíbula/anatomía & histología , Cefalometría , Estudios Transversales , Tamaño de los Órganos , Factores Sexuales , Estadísticas no ParamétricasRESUMEN
A modified in situ model to assess enamel demineralization around orthodontic devices was developed and a pilot study was conducted to evaluate two types of archwire ligation. Enamel blocks were placed in palatal removable appliances where orthodontic brackets were bonded. The brackets on one side of the appliance were ligated with elastomeric rings and those on the other side with stainless steel wires. Four volunteers (two males, two females), mean age 27 years, wore the appliances for 14 days during which time a 20 per cent sucrose solution was dripped eight times a day onto the enamel blocks. The biofilm formed around the brackets was collected for microbiological analyses and the mineral loss around the brackets was determined by cross-sectional microhardness measurement. The ligatures evaluated did not differ significantly from each other regarding biofilm weight, total bacteria, total streptococci, mutans streptococci, or lactobacilli counts (P > 0.05, Wilcoxon paired test). Enamel demineralization was also not different around the brackets for the different ligation methods (P > 0.05, split-split-plot analysis of variance). However, a statistical power analysis based on the data showed a trend to higher demineralization around brackets ligated with elastomeric rings. The developed modified in situ model may be suitable to assess the caries potential of clinical procedures used in orthodontic treatment.
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Caries Dental/etiología , Esmalte Dental/patología , Soportes Ortodóncicos , Alambres para Ortodoncia/clasificación , Desmineralización Dental/etiología , Adulto , Animales , Biopelículas , Cariogénicos/administración & dosificación , Bovinos , Recuento de Colonia Microbiana , Aleaciones Dentales/química , Caries Dental/microbiología , Esmalte Dental/microbiología , Materiales Dentales/química , Elastómeros/química , Femenino , Dureza , Humanos , Lactobacillus/aislamiento & purificación , Masculino , Proyectos Piloto , Acero Inoxidable/química , Streptococcus/aislamiento & purificación , Streptococcus mutans/aislamiento & purificación , Sacarosa/administración & dosificación , Desmineralización Dental/microbiologíaRESUMEN
OBJETIVO: o presente estudo verificou o efeito do uso do aparelho extrabucal (AEB) sobre a intensidade da reabsorção radicular apical nos primeiros molares permanentes superiores submetidos à ação do aparelho. MÉTODOS: foram avaliadas as radiografias periapicais da região dos primeiros molares permanentes superiores, bilateralmente, de 19 jovens leucodermas, do gênero feminino, com idades entre 8 e 10 anos, com má oclusão do tipo Classe II, 1ª divisão dentária, pré e pós-tratamento com AEB de tração alta. As 76 radiografias foram divididas em dois grupos, de acordo com o grau de formação radicular. O grupo A consistiu de 18 radiografias com formação radicular incompleta, com exceção da raiz palatina, ao início do tratamento e 18 ao final. O grupo B consistiu de 20 radiografias com formação radicular completa ao início do tratamento e 20 ao final. Mensurou-se os comprimentos radiculares utilizando um paquímetro digital e submeteu-se as medidas obtidas ao teste de erro do método e à análise estatística (teste t de Student) para verificar as diferenças no comprimento radicular antes e após o tratamento com o AEB. RESULTADOS: no grupo A ocorreu um aumento significativo dos comprimentos radiculares, enquanto no grupo B as diferenças dos comprimentos radiculares não foram significativas. As medidas pós-tratamento no grupo A não diferiram das medidas pré-tratamento no grupo B, ou seja, os dentes com formação radicular incompleta ao início do tratamento apresentaram crescimento radicular normal durante o tratamento ativo. CONCLUSÃO: concluiu-se que o uso do AEB não influenciou negativamente na formação radicular e não provocou reabsorção apical nos molares submetidos à ação do aparelho, sugerindo que o AEB não apresentou riscos à estrutura e formação radicular quando corretamente indicado e aplicado.
AIM: The aim of this study was to verify the effect of occipital headgear wear on the intensity of apical root resorption of the upper first permanent molars submitted to the action of the appliance. METHODS: Were evaluated periapical X-rays of 19 leucoderms young female - with ages between 8 and 10 years, with dental Class II, division 1 malocclusion, before and after orthodontic treatment, using high-pull headgear. The 76 X-rays were divided into two groups according to their root formation. Group A consisted of 18 X-rays with incomplete root formation, except for the palatine root, before treatment and 18 after treatment. Group B consisted of 20 X-rays where root formation was completed before treatment and 20 after treatment. The root lengths were measured with digital caliper and the registered measures were submitted to the error of the method and statistical analysis, Student t test, to verify the differences regarding the root length before and after the treatment with occipital headgear. RESULTS: In group A, there was a significant increase of the root lengths, while in the group B the differences were not significant. Posttreatment Group A showed no significant differences with the mean root lengths of pretreatment group B, in other words, teeth with incomplete root formation at onset of orthodontic treatment presented normal root growth during the active treatment. CONCLUSION: Therefore, it was concluded that high-pull headgear didn't influence negatively in the root formation and it didn't provoke apical resorption of the molars submitted to the action of the appliance, suggesting that occipital headgear doesn't present risks to the root structure and formation when correctly indicated and applied.
Asunto(s)
Humanos , Femenino , Niño , Diente Molar , Maloclusión Clase II de Angle , Aparatos Ortodóncicos , Resorción RadicularRESUMEN
OBJECTIVE: To assess, by systematically reviewing the literature, the functional changes of the masticatory muscles associated with posterior crossbite in the primary and mixed dentition. MATERIALS AND METHODS: A literature survey from the Medline database covering the period from January 1965 to February 2008 was performed. Randomized controlled trials, controlled clinical trials, and clinical trials that evaluated bite force, surface electromyography, and signs and symptoms of temporomandibular disorders (TMD) were included. Two reviewers extracted the data independently and assessed the quality of the studies. RESULTS: The search strategy resulted in 494 articles, of which 8 met the inclusion criteria. Children with posterior crossbite can have reduced bite force and asymmetrical muscle function during chewing or clenching, in which the anterior temporalis is more active and the masseter less active on the crossbite side than the noncrossbite side. Moreover, there is a significant association between posterior crossbite and TMD symptomatology. CONCLUSION: The consequences of the functional changes for the growth and development of the stomatognathic system deserves further investigation.
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Maloclusión/fisiopatología , Músculos Masticadores/fisiopatología , Fuerza de la Mordida , Ensayos Clínicos como Asunto , Ensayos Clínicos Controlados como Asunto , Dentición Mixta , Electromiografía , Humanos , Masticación/fisiología , Ensayos Clínicos Controlados Aleatorios como Asunto , Trastornos de la Articulación Temporomandibular/fisiopatología , Diente PrimarioRESUMEN
The aim of this study was to improve the mustard oil (MO) induced temporomandibular joint (TMJ) nociception model and to investigate the potential analgesic activity of systemic dipyrone and tramadol on the nociceptive behavioral responses induced by injection of low concentrations of the MO into the rat TMJ region. TMJ injection of 2.5% MO produced a significant nociceptive behavior expressed by head flinching and orofacial rubbing. This activity was related to the MO injection since mineral oil (vehicle) did not elicit response. Local application of the lidocaine N-ethyl bromide quaternary salt, QX-314 (2%) and systemic administration of morphine (4 mg/kg) significantly reduced the MO-induced nociceptive responses, validating the nociceptive character of the behaviors. The pretreatment with systemic dipyrone (19, 57 or 95 mg/kg) as well as tramadol (5, 7.5 or 10 mg/kg) was effective in decreasing the nociceptive behavioral responses induced by the injection of MO into the rat TMJ. In conclusion, TMJ injection of low concentrations of MO in rats produces well defined and quantifiable nociceptive behaviors constituting a reliable behavioral model for studying TMJ pain mechanisms and testing analgesic drugs. The results also suggest that dipyrone and tramadol could be effective analgesic options in the management of TMJ pain.
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Analgésicos no Narcóticos/farmacología , Analgésicos Opioides/farmacología , Conducta Animal/efectos de los fármacos , Dolor/inducido químicamente , Dolor/psicología , Aceites de Plantas/farmacología , Articulación Temporomandibular/efectos de los fármacos , Anestésicos Locales/farmacología , Animales , Antiinflamatorios no Esteroideos/farmacología , Dipirona/farmacología , Relación Dosis-Respuesta a Droga , Lidocaína/análogos & derivados , Lidocaína/farmacología , Morfina/farmacología , Planta de la Mostaza , Ratas , Tramadol/farmacologíaRESUMEN
OBJECTIVES: To determine if systemic stress affects the biological reactions occurring during orthodontic tooth movement. METHODS: Four groups of male 10 week-old Wistar rats were used. Group A animals (N=10) were restrained for one hour per day for 40 days; Group B animals (N=10) were restrained for one hour per day for three days; Group C (N=10) and Group D (N=8) animals were unrestrained. The upper left first molars in the rats in Groups A (long-term stress), B (short-term stress) and C (control) were moved mesially during the last 14 days of the experiment. The animals in Group D (N=8) were used for body weight and hormonal dosage comparisons only. They were not subjected to any stress and did not have appliances fitted. All animals were killed at 18 weeks of age and blood collected for measurement of plasma corticosterone. Tooth movement was measured with an electronic caliper. The right and left hemi-maxillae of five rats from each group were removed and the number of tartrate-resistant acid phosphatase (TRAP) positive cells, defined as osteoclasts, adjacent to the mesial roots of the upper first molars counted. The contralateral side in each animal served as the control (split-mouth design). RESULTS: Corticosterone levels were significantly higher in the stressed groups (Groups A and B) than in the control group (Group C). Tooth movement was significantly greater in Group A (long-term stress) compared with Group B (short-term stress) and Group C (control), which did not differ from each other. There were significantly more osteoclasts in the long-term stress group than in the short-term stress and control groups. CONCLUSION: Persistent systemic stress increases bone resorption during orthodontic tooth movement. Systemic stress may affect the rate of tooth movement during orthodontic treatment.
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Pérdida de Hueso Alveolar/fisiopatología , Análisis del Estrés Dental , Estrés Fisiológico/fisiología , Técnicas de Movimiento Dental , Proceso Alveolar/fisiología , Animales , Remodelación Ósea/fisiología , Recuento de Células , Corticosterona/sangre , Masculino , Enfermedades Maxilares/fisiopatología , Osteoclastos , Ratas , Ratas Wistar , Factores de TiempoRESUMEN
Aim: The aim of this study was to evaluate the effect of two consecutive recycling procedures on the shear bond strength of different orthodontic adhesives. Methods: Edgewise brackets were bonded to the buccal surfaces of 40 bovine incisors using the following bonding materials: Concise (group I), Transbond XT (group II), Smart Bond (group III) and Fuji Ortho (group IV). The teeth were stored in water at 37°C for 24 h, thermocycled between 5 and 55°C, and debonded using an Instron machine at a crosshead speed of 0.5 mm/min. In all groups, the bonded brackets were detached and rebonded after recycling by 50-µm particle aluminum oxide blasting. After the second recording of retentive strengths, the recycling procedure, the rebonding and the shear bond strength test were repeated. Data were analyzed statistically by ANOVA and Tukeys test at 5% significance level. Results: The results showed that repeated recycling did not interfere in retention of brackets, regardless of the adhesive used. The highest shear bond strength values were obtained after bonding with Transbond XT, independent of the recycling procedure. Conclusion: Repeated bracket recycling using 50-µm aluminum oxide particle air abrasion did not affect the shear bond strength of metallic brackets bonded with different orthodontic adhesives.