The influence of protective varnish on the integrity of orthodontic cements.

OBJECTIVE: The aim of the present study was to assess the influence of saliva contamination over the structural strength and integrity of conventional glass-ionomer cements used for cementing orthodontic bands in the absence and presence of a surface-protecting varnish. METHODS: 48 samples were prepared by inserting 3 types of glass-ionomer cements into standardized metallic matrixes with 10 mm of diameter and 2 mm of depth. The cements used were: Meron (VOCO), Ketac-Cem (3M ESPE) and Vidrion C (DFL), all of which comprised groups A, B and C, respectively. Subgroups A1, B1 and C1 comprised samples with no surface protection, whereas subgroups A2, B2 and C2 comprised samples of which surface was coated with Cavitine varnish (SS White), after cement manipulation and application, in order to protect the cement applied. All samples were stored in artificial saliva for 24 hours at 37°C. A Vickers diamond micro-durometer was used to produce indentations on the non-treated group (non-varnished) and the treated group (varnished). RESULTS: Varnished materials had significantly higher microhardness values in comparison to non-varnished materials. Ketac-Cem had the highest microhardness value among the varnished materials. CONCLUSIONS: Varnish application is necessary to preserve the cement and avoid enamel decalcification. Glass-ionomer cements should be protected in order to fully keep their properties, thus contributing to dental health during orthodontic treatment.

The influence of protective varnish on the integrity of orthodontic cements

OBJECTIVE: The aim of the present study was to assess the influence of saliva contamination over the structural strength and integrity of conventional glass-ionomer cements used for cementing orthodontic bands in the absence and presence of a surface-protecting varnish. METHOD: 48 samples were prepared by inserting 3 types of glass-ionomer cements into standardized metallic matrixes of 10 mm of diameter and 2 mm of depth. The cements used were: Meron (VOCO), Ketac-Cem (3M ESPE) and Vidrion C (DFL), all of which comprised groups A, B and C, respectively. Subgroups A1, B1 and C1 comprised samples with no surface protection, whereas subgroups A2, B2 and C2 comprised samples of which surface was coated with Cavitine varnish (SS White), after cement manipulation and application, in order to protect the cement applied. All samples were stored in artificial saliva for 24 hours at 37ºC. A Vickers diamond micro-durometer was used to produce indentations on the non-treated group (non-varnished) and the treated group (varnished). RESULTS: Varnished materials had significantly higher microhardness values in comparison to non-varnished materials. Ketac-Cem had the highest microhardness value among the varnished materials. CONCLUSION: Varnish application is necessary to preserve the cement and avoid enamel decalcification. Glass-ionomer cements should be protected in order to fully keep their properties, thus, contributing to dental health during orthodontic treatment.

OBJETIVO: avaliar a influência da contaminação salivar na resistência estrutural e integridade de cimentos de ionômero de vidro convencionais utilizados para cimentação de bandas ortodônticas na ausência e na presença de um verniz protetor de superfície. MÉTODOS: quarenta e oito corpos de prova foram confeccionados a partir de três cimentos ortodônticos, com auxílio de matrizes metálicas padronizadas com 10mm de diâmetro e 2mm de altura. Os cimentos utilizados foram: Meron (Voco), Ketac-Cem (3M ESPE) e Vidrion C (DFL), compondo os grupos A, B e C, respectivamente. Metade dessas amostras não recebeu nenhum tipo de proteção superficial, constituindo os subgrupos A1, B1 e C1, enquanto, os subgrupos A2, B2 e C2 tiveram suas superfícies isoladas com verniz Cavitine (SS White) após manipulação e aplicação do cimento, com intuito de proteger a superfície do cimento. As amostras foram armazenadas em saliva artificial por 24 horas a 37ºC. Foi realizado um ensaio de microdureza (Vickers) para avaliação da dureza de superfície do grupo não-tratado (sem isolamento) e do grupo tratado (agente protetor). RESULTADOS: os materiais previamente isolados com o verniz obtiveram valores de microdureza significativamente maiores que os não-isolados. O cimento Ketac-Cem apresentou, estatisticamente, a maior microdureza entre os materiais protegidos. CONCLUSÃO: o isolamento com verniz mostrou-se necessário para preservação do cimento e, consequentemente, de sua capacidade de evitar possíveis desmineralizações dentárias. Os cimentos de ionômero de vidro devem ser protegidos para manutenção de sua integridade, contribuindo para saúde dental durante o tratamento ortodôntico.

Angle Class III malocclusion treated with mandibular first molar extractions.

A Class III malocclusion associated with dental asymmetry is a complex diagnostic and treatment problem in orthodontics. The goals of maintaining or improving the facial profile and achieving good function are decisive factors when considering whether to plan a surgical or a nonsurgical treatment approach. A fixed appliance in combination with extractions could be considered for nonsurgical management of this type of malocclusion in the permanent dentition. This article presents the results of an orthodontic approach to a Class III subdivision malocclusion in an adult treated with mandibular first molar extractions. The extractions provided the space needed to correct the overjet and overbite and to improve the intercuspation.

Effects of induced precocious puberty on cranial growth in female Wistar rats.

This investigation examined the effects of pharmacologically induced precocious puberty on cranial growth in Wistar rats. Forty-eight female newborn Wistar rats were divided into two groups: a control group (C) and an experimental group (E), with four subgroups of six animals each. The time interval from birth until sacrifice differed between the subgroups, and was set at 30, 60, 90, and 120 days. An intramuscular single dose (300 µg) of steroid hormone danazol was administered on day 5 after birth, as a means of inducing precocious puberty. Alizarin (2 mg/100 g) was administered to three animals in each subgroup three days prior to sacrifice. Body mass and dates corresponding to the beginning of the oestrous cycle were recorded. Craniometric measurements were undertaken. Histological analysis using light and fluorescence microscopy was then carried out to qualitatively and quantitatively evaluate the spheno-occipital synchondrosis and to visualize bone deposition patterns. The results were analysed with a Student's t-test and analysis of variance. Precocious puberty was effectively induced and differences between groups denoted an earlier maturation in the experimental rats. In qualitative analysis, a significant increase of total synchondrosis width was noted only in group E60, in comparison with C60, and an increase in the E90 subgroup cortical bone width compared with the C90 subgroup. Histomorphometrically, a statistical difference between total width values of subgroups E60 (434.3 µm) and C60 (323.5 µm) was detected. However, body mass and macroscopic measurements did not show statistically significant differences. An appropriate model for studying bone growth associated with precocious puberty in Wistar female rats was not achieved using steroid hormone danazol, when evaluated at 30 day intervals.

Adenoid hypertrophy and open bite

Aim: To evaluate if the constricted airway passage, measured by the nasopharyngeal (NP) and oropharyngeal (OP) width, has a correlation to anterior open bite. Methods: Lateral cephalometric radiographs of 43 patients with anterior open bite (26 with mixed dentition and 17 with permanent dentition) and 30 patients with overbite (15 with mixed dentition and 15 with permanent dentition) were obtained from de Department of Pediatric Dentistry and Orthodontics of the Federal University of Rio de Janeiro for examination. Eight patients with syndromes were excluded from study. Cephalometric measurements were carried out using Dolphin Imaging & Management SolutionsTM software (Chatsworth, CA, USA). Measures of NP and OP were evaluated according to the McNamara’s soft tissue analysis and were correlated with the presence of open bite or overbite. Student’s t test and chi-square were used to assess statistical differences in continuous and dichotomic variables, respectively. Kruskal-Wallis test was employed to compare multiple variables. Results: Open bite patients showed significant decreased mean NP and OP values compared to overbite patients. Lack of labial seal was observed in all open bite patients. When patients with mixed and permanent dentitions were analyzed separately, the mean NP value was still significantly smaller in the open bite group. However, the mean OP values were smaller in the open bite group in both dentitions analysis, but were not statistically different. Conclusions: All patients with anterior open bite had reduced NP and OP measures compared to overbite patients, in spite of dentition.

Ceramic surface polishing techniques after removal of orthodontic adhesive.

OBJECTIVE: Verify the in vitro effectiveness of different porcelain surface polishing systems used after orthodontic debonding. MATERIALS AND METHODS: Restorations were simulated by 52 metallic samples covered with glazed feldspathic porcelain. Four of these intact samples composed the control group (C). The remaining samples were divided into four groups (n = 12), according to the surface preparation they were to receive: no surface treatment (G1); roughened with a diamond bur (G2); etched with 10% hydrofluoric acid (G3); and sandblasted with aluminum oxide (G4). All experimental samples were treated with silane and bonded with a primer and standardized amount of adhesive. After composite removal, each group was divided into subgroups randomly (n = 4), according to the porcelain polishing system used: Edenta (P1); Identoflex (P2); and Komet (P3). All 52 sample-surfaces were evaluated quantitatively with a profilometer, and a mean roughness profile (Ra) value was determined for each sample. Both control and experimental specimens were evaluated qualitatively using a scanning electron microscope (SEM) to assess surface morphology. RESULTS: Statistical analysis with analysis of variance (ANOVA) and post-hoc Tukey multiple comparisons test showed statistical differences between surface preparation groups (G1 not equal G2 = G3 = G4), at alpha = .05 level of significance; as for polishing protocols, no statistical difference was found. CONCLUSIONS: The surface preparation was the determinant for final surface texture. No combination between surface preparation and polishing system was able to reestablish the original glazed porcelain smoothness.

Avaliação cromática do esmalte submetido à clareação dentária com peróxido de hidrogênio a 35% após tratamento ortodôntico / Colour evaluation of enamel submitted to 35 % hydrogen peroxide thooth whitening after orthodontic treatment

Objetivo: avaliar as possíveis alterações cromáticas ocorridas na superfície dos dentes (pré-tratamento ortodontico; pós-descolagem e acabamento, e pós-clareação com peróxido de hidrogênio a 35 %), bem como verificar o grau de diferença de cor entre a área que sofreu intervenção ortodôntica e a que não sofreu. Metodologia: trinta peças confeccionadas com dentes bovinos foram divididas em grupo controle (I) e experimental (II), sendo igualmente preparadas e armazenadas em saliva artificial, em estufa (37ºC), durante todo o experimento. No grupo II, os acessórios ortodônticos foram colocados em resina fotopolimeralizável, seguido da descolagem e remoção da resina remanescente. Em seguida, nos dois grupos, foi realizada a clareação com peróxido de hidrogênio a 35 %, seguindo as especificações do fabricante. Um espectrofotômetro computadorizado foi utilizado para os testes colorimétricos nos grupos I (T1 - início; T3 - pós-clareação) e II (T1 - início; T2 - pós-descolagem; T3 - pós-clareação) e os valores avaliados pelo sistema CIELAB, sendo usados apenas os valores de L* (escurecimento ou clareação do dente, numa escala de 0-100) e grau de amarelo. Resultados: houve um aumento nos valores de L* (luminosidade) entre T1/T3 para ambos os grupos e entre T2/T3 para o grupo II, e uma diminuição nos valores de grau amarelo ente T1/T3 em ambos os grupos e entre T2/T3 para o grupo II. Conclusão: não houve diferença de resposta à clareação dentária, imediatamente após a remoção do aparelho, entre dentes submetidos à colagem ortodôntica e dentes não colados, não sugerindo haver influência do provável remanescente resinoso na coloração dentária imediata.

Puberdade precoce: informações de interesse para o ortodontista / Early puberty: information of interest to the orthodontist

A puberdade é um período de modificações biopsicossociais intensas, pelo qual os indivíduos passam até que alcancem a maturidade sexual. Pode ser diagnosticada, clinicamente, por meio do surgimento das características sexuais secundárias. Nesse período, ocorrem as taxas de crescimento mais significativas da face, constituindo um momento de grande interesse para o ortodontista, no manejo das desarmonias esqueléticas faciais. Algumas crianças atingem a puberdade em idade anterior à média populacional, o que é denominado puberdade precoce. Este trabalho visa apresentar uma revisão da literatura sobre puberdade normal e puberdade precoce, direcionada ao diagnóstico ortodôntico, ilustrando idades dentária e esquelética precoces, em relação à idade cronológica, em uma paciente de 8 anos de idade. A idade óssea é a forma mais indicada para determinar o melhor momento de intervenção ortopédica na face, inclusive em pacientes portadores de puberdade precoce, nos quais o crescimento puberal pode ser finalizado antes mesmo de ser completada a troca dos molares decíduos.

Mordida cruzada posterior funcional: uma alternativa de tratamento / Posterior functional crossbite: an alternative of treatment

O objetivo deste trabalho é apresentar uma revisão da literatura sobre mordida cruzada posterior funcional e seu tratamento interceptador, mostrando, a seguir, dois casos clínicos de pacientes tratados na clínica de Graduação de Ortodontia da Faculdade de Odontologia da Universidade Federal do Rio Grande do Sul no período de 2001 a 2003. Nesses pacientes corrigiram-se as inclinações dentárias através de placa ortodôntica superior removível em acrílico com parafuso expansor, adequando as dimensões transversais dos arcos. Entretanto, em função do componente muscular, ambos persistiram desviando a mandíbula durante o fechamento. Houve, então, a necessidade da utilização de outro aparelho ortodôntico removível com uma extensão vertical como guia para o fechamento e, conseqüentemente, para a desprogramação da musculatura. Foi observado que, após a utilização deste aparelho, os pacientes não mais apresentavam um padrão de fechamento mandíbular com desvio. Considerando que as correções das mordidas cruzadas, após o período de tratamento e contenção, são estáveis, está indicada a intervenção o quanto antes, pois, além de permitir o crescimento e o desenvolvimento normais, melhora a mastigação e evita desgastes dentários