Effect of oral exposure on chemical, physical, mechanical, and morphologic properties of clear orthodontic aligners

The dental industry is heavily committed to developing more esthetic solutions for orthodontic treatments. Invisalign is a system of transparent orthodontic aligners introduced as an alternative to conventional orthodontic fittings with brackets and metal wires. This study aimed to assess the chemical, physical, mechanical and morphologic changes in these polymeric aligners after exposure to the oral environment. Twenty-four Invisalign orthodontic aligners were equally divided into 2 groups: an in vivo aged group in which patients used aligners for 14 days and the reference group, unexposed to the oral environment. Different experimental techniques were used to study the chemical structure, the color changes and translucency, the density and subsequent volume of the aligners, mechanical properties, surface roughness, morphology and elemental composition. The data were subjected to several statistical analyses. Clear orthodontic aligners exhibit chemical stability but undergo a statistically significant optical change in color and translucency. There was a gradual increase in the water absorption rate and the dimensional variation of the polymer, indicating a strong correlation among these factors. The mechanical properties of the polymer showed a statistically significant decrease in its elastic modulus and hardness. There was a slight tendency toward increased surface roughness of the material, but no statistical differences were found between reference and aged groups. The surface morphology of the used aligners demonstrates microcracks, distortions and biofilm formation. Intraoral aging adversely affected the physical, mechanical, and morphologic properties of the Invisalign appliance.

Effect of oral exposure on chemical, physical, mechanical, and morphologic properties of clear orthodontic aligners.

INTRODUCTION: The dental industry is heavily committed to developing more esthetic solutions for orthodontic treatments. Invisalign is a system of transparent orthodontic aligners introduced as an alternative to conventional orthodontic fittings with brackets and metal wires. This study aimed to assess the chemical, physical, mechanical and morphologic changes in these polymeric aligners after exposure to the oral environment. METHODS: Twenty-four Invisalign orthodontic aligners were equally divided into 2 groups: an in vivo aged group in which patients used aligners for 14 days and the reference group, unexposed to the oral environment. Different experimental techniques were used to study the chemical structure, the color changes and translucency, the density and subsequent volume of the aligners, mechanical properties, surface roughness, morphology and elemental composition. The data were subjected to several statistical analyses. RESULTS: Clear orthodontic aligners exhibit chemical stability but undergo a statistically significant optical change in color and translucency. There was a gradual increase in the water absorption rate and the dimensional variation of the polymer, indicating a strong correlation among these factors. The mechanical properties of the polymer showed a statistically significant decrease in its elastic modulus and hardness. There was a slight tendency toward increased surface roughness of the material, but no statistical differences were found between reference and aged groups. The surface morphology of the used aligners demonstrates microcracks, distortions and biofilm formation. CONCLUSION: Intraoral aging adversely affected the physical, mechanical, and morphologic properties of the Invisalign appliance.

Efeito da fumaça de cigarro sobre alinhadores ortodônticos transparentes / Effect of cigarette smoke on clear orthodontic aligners

O objetivo deste trabalho foi investigar as alterações nas propriedades ópticas de cor e de luz transmitida e na rugosidade de superfície do polímero constituinte de alinhadores transparentes após a exposição à fumaça de cigarro. A amostra foi constituída de 20 superfícies das faces vestibulares de incisivos centrais superiores obtidas através de 10 alinhadores de alinhadores ortodônticos (Invisalign®). As amostras foram divididas igual (n=10) e aleatoriamente em 2 grupos: grupo controle (GC) e grupo experimental (GE). Para a exposição do GE à fumaça de cigarro foi utilizado um dispositivo de acrílico hermeticamente fechado, onde as amostras foram expostas a 21 ciclos de fumaça e posteriormente armazenadas em saliva artificial à 37ºC por 15 dias. O GC foi exposto somente à saliva artificial nas mesmas condições, pelo mesmo período. Para avaliar as mudanças de cor e transmitância foi utilizado um espectrofotômetro calibrado pelo sistema cores CIE (L*a*b*) e utilizado o National Bureal of Standards (NBS) para classificação clínica da alteração de cor. A diferença total de cor (∆E) e o NBS entre os grupos foi calculado. Foram feitas medidas de cor e transmitância inicial (T0), ou seja, antes da exposição à fumaça de cigarro e à saliva artificial e final (T1), registradas após a exposição ao cigarro e à saliva. A rugosidade foi avaliada através do rugosímetro digital e foram medidas a rugosidade em T0 e T1. Foram utilizados os parâmetros de rugosidade Ra (rugosidade média) e Rz (rugosidade de profundidade média). Para comparar os valores dos parâmetros de cor, transmitância e rugosidade entre GC e GE foi utilizado o teste t para amostras independentes. Para comparar os valores dos parâmetros analisados intragrupo ao longo do tempo (T0 e T1) foi utilizado o teste t para amostras pareadas. Em todas as análises foi estabelecido um nível de significância de 0,05. Para todos os parâmetros de cor em T1 houve diferença (p<0,05) quando comparados GC (L: 87,400 ± 0,681; a: 0,746 ± 0,094; b: 3,393 ± 0,171) com GE (L: 77,208 ± 3,337; a: 1,576 ± 0,025; b: 6,747 ± 0,557). O ΔE do GC (2,39) e GE (14,27) apresentaramse diferentes (p=0,002), ao converter tais valores para a escala NBS, resultaram em um valor de 2,20 e 13,13. Ao comparar os grupos houve diminuição da transmitância (p=0,014) sendo de maior magnitude no GE. Em T1 entre GC e GE houve diferença (p=0,046) para Ra (GC: 0,122 ± 0,002; GE: 0,139 ± 0,007), sendo maiores os valores no GE. Para Rz, quando comparados GC (0,616 ± 0,021) e GE (0,741 ± 0,026), em T1, também houve diferença (p=0,002), sendo também maiores os valores encontrados no GE. No GC não houve diferença estatisticamente significativa de Ra (p=0,807) e Rz (p=0,231) quando comparadas as amostras ao longo do tempo T0 e T1. No GE ocorreu tanto aumento de Ra (p=0,003) e de Rz (p=0,014). Conclui-se, portanto, que os alinhadores se tornaram mais escuros, amarelados, diminuíram sua transmissão de luz, tornando-se opacos e tiveram sua rugosidade superficial aumentada, tanto no parâmetro Ra quanto Rz. (AU)

The aim of this study was to investigate the changes in the optical properties of color and transmitted light and in the surface roughness of the constituent polymer of clear aligners after exposure to cigarette smoke. The sample consisted of 20 surfaces of the buccal surfaces of the upper central incisors of aligners (Invisalign®). The samples were divided equally (n=10) and randomly into 2 groups: control group (CG) and experimental group (EG). For the exposure of the EG to cigarette smoke, a hermetically closed acrylic device was used, where the samples were exposed to 21 smoke cycles and later stored in artificial saliva at 37ºC for 15 days. The CG was only exposed to artificial saliva under the same conditions, for the same period. To evaluate changes in color and transmittance, a spectrophotometer calibrated by the CIE color system (L*a*b*) was used and the National Bureau of Standards (NBS) was used for clinical classification of the color change. The total difference in color (∆E) and NBS between groups was calculated. Initial (T0) color and transmittance measurements were taken, that is, before exposure to cigarette smoke and artificial saliva, and final (T1), recorded after exposure to cigarettes and saliva. Roughness was evaluated using a digital roughness meter and roughness was measured at T0 and T1. The roughness parameters Ra (mean roughness) and Rz (mean depth roughness) were used. To compare the values of color, transmittance and roughness parameters between GC and EG, the t test for independent samples was used. To compare the values of the parameters analyzed within the group over time (T0 and T1), the t test for paired samples was used. In all analyses, a significance level of 0.05 was established. There was a difference (p<0.05) for all color parameters in T1 when comparing GC (L: 87.400 ± 0.681; a: 0.746 ± 0.094; b: 3.393 ± 0.171) with GE (L: 77.208 ± 3.337; a: -1.576 ± 0.025; b: 6.747 ± 0.557). The ΔE of the GC (2.39) and GE (14.27) were different (p=0.002), when converting these values to the NBS scale, resulted in a value of 2.20 and 13.13. Comparing the groups there was a decrease in transmittance (p=0.014), with greater magnitude in the GE. At T1, there was a difference (p=0.046) between GC and GE for Ra (GC: 0.122 ± 0.002; GE: 0.139 ± 0.007), with higher values in EG. For Rz, when comparing GC (0.616 ± 0.021) and GE (0.741 ± 0.026), at T1, there was also a difference (p=0.002), with higher values found in GE. In the CG, there was no statistically significant difference in Ra (p=0.807) and Rz (p=0.231) when comparing samples over time T0 and T1. In the GE, there was both an increase in Ra (p=0.003) and Rz (p=0.014). It is concluded, therefore, that the aligners became darker, yellowish, reduced their light transmission, becoming opaque and had their surface roughness increased, both in the Ra and Rz parameters. (AU)

Anterior open bite treated with palatine crib: a case report with cephalometric, speech and electromyography analyses

This case report describes an interceptive treatment of anterior open bite (AOB) with fixed palatine grid using clinical, cephalometric, electromyographic and speech analysis data. Case report: An 8-year-old girl, Angle Class I malocclusion presenting AOB. The complete orthodontic documentation was obtained and the perioral muscles were evaluated using the electromyography during blowing, sucking and smiling activities, before and after treatment. Speech acoustic evaluation was performed through the frequencies of the formants to assess the position of the tongue. Results: The AOB was corrected in six months with reduction of vertical transpass, decrease of cephalometric Angles 1: NA and 1: NB and increase of interincisal angle. During the smile movement, it was possible to observe the decrease of the muscular activity of the superior orbicularis muscle and the increase of the muscular activity of the inferior orbicularis. In the blow movement, there was a tendency to decrease muscle activity. Opposite directions were observed at the time of installation of the grid in the frequencies of the formants. When the grid was removed, the tongue was lowered and posteriorized in relation to the installation time. When compared the final and initial moments, it was noted a predominance of tongue lower position, besides posteriorization in some vowels and anteriorization in others. Conclusion: After the use of the fixed palatine crib as an interceptive treatment for AOB, the bite was closed and it was possible to observe an harmony in the patient profile and improvement in periorbital musculature and tongue positioning.

Objetivo: Este relato de caso descreve um tratamento interceptivo da mordida aberta anterior (MAA) com grade palatina fixa usando dados clínicos, cefalométricos, eletromiográficos e de fala. Relato do caso: Menina de 8 anos de idade apresentando maloclusão Classe I de Angle e MAA. A documentação ortodôntica completa foi obtida e os músculos periorais foram avaliados pela eletromiografia durante as atividades de sopro, sucção e sorriso, antes e após o tratamento. A avaliação acústica da fala foi realizada através das frequências dos formantes para avaliar a posição da língua. Resultados: O MAA foi corrigida em seis meses com redução do transpasse vertical, diminuição dos ângulos cefalométricos 1: NA e 1: NB e aumento do ângulo interincisivo. Durante o movimento do sorriso, foi possível observar a diminuição da atividade muscular do músculo orbicular superior e o aumento da atividade muscular do orbicular inferior. No movimento do sopro, houve uma tendência a diminuir a atividade muscular. Direções opostas foram observadas no momento da instalação da grade nas frequências dos formantes. Quando a grade foi removida, a língua foi abaixada e posteriorizada em relação ao tempo de instalação inicial do aparelho. Quando comparados os momentos final e inicial, observou-se predomínio da posição inferior da língua, além de posteriorização em algumas vogais e anteriorização em outras. Conclusão: Após o uso da grade palatina fixa como tratamento interceptivo para a MAA, a mordida foi fechada e foi possível observar harmonia no perfil da paciente e melhora da musculatura periorbital e posicionamento da língua.

Influence of cigarette smoke on enamel color stability after orthodontic debonding: an in vitro study

Objective: The aim of this study was to evaluate the color stability of dental enamel exposed to cigarette smoke after orthodontic debonding. Methods: Thirty-two bovine incisors were allocated into control (C1 and C2) and experimental groups (n=8) according to distinct bonding protocols: with adhesive (B1) and without adhesive (B2) and exposure to cigarette smoke. Samples from B1, B2 and C2 were exposed to ten cycles of smoke in a specific and hermetic chamber while the C1 remained stored in artificial saliva. Color analysis was performed with a spectrophotometer according to the L*a*b* system. Intergroup comparisons and effect of time were estimated with ANOVA/Tukey and paired Student t tests, respectively (a=0.05). Results: Statistically significant color changes have not been observed in C1 (L*: -0.69 ± 0.80; a*: 0.36 ± 0.23; b*: 0.17 ± 0.50) and without adhesive (B2) (L*: -3.74 ± 2.85; a*: 0.93 ± 0,73; b*: 1.13 ± 1.16) through the study time (p>0,05). However, the group with adhesive (B1) presented significant color changes in L*:-5.55 ± 2.28, a*: 2.33 ± 0.77 and b*: 3.30 ± 1.37, what means, darker, greener and more yellow, respectively (p<0,05) and the control group that was exposed to the cigarette smoke (C2) presented significant color changes in L*: -1.72 ± 0.28 e b*: 1.82 ± 0.22, what means, darker and more yellow, respectively. Conclusion: Enamel color stability was affected by exposure to cigarette smoke after orthodontic debonding, especially when bonding protocolcomprised the application of primer adhesive.

Objetivo: O objetivo deste estudo foi avaliar a estabilidade da cor do esmalte dentário exposto à fumaça de cigarro após a descolagem ortodôntica. Métodos: Trinta e dois incisivos bovinos foram alocados nos grupos controle (C1 and C2) e experimental (n = 8) de acordo com protocolos de colagem ortodôntica distintos: com adesivo (B1) e sem adesivo (B2) e expostos à fumaça de cigarro. Amostras do B1, B2 e C2 foram expostas a dez ciclos de fumaça em uma câmara específica e hermética, enquanto o C1 permaneceu armazenado em saliva artificial. A análise da estabilidade de cor foi realizada com um espectrofotômetro de acordo com osistema L* a* b*. As comparações intergrupos e o efeito do tempo foram verificados com ANOVA / Tukey e testes t de Student, respectivamente (a=0,05). Resultados: Não foram observadas alterações de cor estatisticamente significativas no C1 (L*: -0,69 ± 0,80; a*: 0,36 ± 0,23; b*: 0,17 ± 0.50) e sem adesivo (B2) (L*: -3,74 ± 2,85; a*: 0,93 ± 0,73; b *: 1,13 ± 1,16) durante o tempo de estudo (p>0,05). No entanto, o grupo com adesivo (B1) apresentou alterações significativas de cor em L*: - 5,55 ± 2,28, a*: 2,33 ± 0,77 eb*: 3,30 ± 1,37, o que significa, mais escuro, mais verde e mais amarelo, respectivamente (p<0,05) e o grupo controle exposto à fumaça de cigarro (C2) apresentou alterações significativas de cor em L*: -1,72 ± 0,28 e b*: 1, 82 ± 0,22, o que significa, mais escuro e mais amarelo, respectivamente. Conclusão: A estabilidade da cor do esmalte foi afetada pela exposição à fumaça de cigarro após a descolagem ortodôntica, principalmente quando o protocolo de colagem incluía a aplicação de adesivo.

Cleidocranial dysostosis: a report on two familial cases / Disostose cleidocraniana: relato de dois casos familiares

Cleidocranial dysostosis is a rare genetic syndrome with an autosomal dominant inheritance pattern. The most common manifestations include clavicular aplasia or hypoplasia, open fontanelles and abnormal dentition. The present report describes two familial cases whose late diagnosis was made by means of clinical and radiographic findings. The treatment was radical, with complete surgical teeth extraction and making of total dental prosthesis.