Is the main goal of mastication achieved after orthodontic treatment? A prospective longitudinal study

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.

Avaliação do dimorfismo sexual e da relação entre as características craniofaciais, dos arcos dentários e do músculo masseter na fase de dentição mista / Evaluation of sexual dimorphism and the relationship between craniofacial, dental arch and masseter muscle characteristics in mixed dentition

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. .

Pain, masticatory performance and swallowing threshold in orthodontic patients

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.

Characteristics of masticatory muscles in children with unilateral posterior crossbite

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.

Evaluation of mandibular length in subjects with Class I and Class II skeletal patterns using the cervical vertebrae maturation

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.

Estudo da reabsorção radicular apical após o uso de aparelho extrabucal no tratamento da má oclusão do tipo Classe II, 1ª divisão dentária / Study of apical root resorption after occipital headgear wear on the treatment of dental Class II, division 1 malocclusion

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.

The effect of repeated bracket recycling on the shear bond strength of different orthodontic adhesives

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 Tukey’s 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.

Influence of ethanol and morphine on pain perception evoked by deep tissue injury

The aim of this study was to evaluate the effect of ethanol and morphine on nociceptive behavioral responses evoked by the injection of formalin into the temporomandibular joint region of rats (the TMJ formalin test). In experiment 1, animals were given an ethanol solution (6.5 por cento) or tap water to drink for 4 and 10 days, before the procedure for TMJ pain. In the group treated for 4 days, significant analgesia was observed in the TMJ formalin test, whereas the group treated for 10 days did not show this effect, revealing the development of tolerance to ethanol antinociceptive effects. In experiment 2, animals were submitted to chronic regimen of ethanol (6.5 por cento for 10 days did not show this effect, revealing the development of tolerance to ethanol antinociceptive effects...