Mechanical influence of thread pitch on orthodontic mini-implant stability

The aim of this study was to evaluate the effect of pitch distance on the primary stability (PS) of orthodontic mini-implants (MIs) in artificial bone. Twenty experimental MIs were allocated to two groups, according to their geometric design: G1(30oX 0.6 mm) and G2(45o X 0.8 mm), and inserted into artificial bone of different densities: D1 (0.32 g/cm3) and D2 (0.64 g/cm3). The maximum insertion torque (IT) and removal torque (RT) values were recorded in N.cm. Loss of torque (LT) values were obtained by calculating the difference between the IT and RT. MI mobility was measured by means of a Periotest assessment. Normality and homogeneity were determined by means of the Kolmogorov-Smirnov and Shapiro-Wilk tests, respectively. A two-way ANOVA was used to detect differences between the mini-implant design and density factors. The ANOVA/Tukey tests were used to determine the intergroup difference. Higher IT values were observed for G2 (p ≤ 0.05) in D2. No statistical difference for RT was observed between the groups, whereas G2 presented higher values only for LT (p ≤ 0.05). The Periotest values (PTV) were higher for G1, in comparison with G2, in D1. G1 presented better PS in D2 (IT, RT and LT), whereas G2 was found to be more stable in D1, after evaluation with Periotest.

The influence of orthodontic fixed appliances on the oral microbiota: A systematic review

Objective: To investigate whether there is scientific evidence to support the hypothesis that the presence of orthodontic fixed appliances influences the oral microbiota. Methods: The search for articles was conducted in PubMed; ISI Web of Knowledge and Ovid databases, including articles published in English until May 17th, 2012. They should report human observational studies presenting the following keywords: "fixed orthodontic appliance" AND "microbiological colonization"; OR "periodontal pathogens"; OR "Streptococcus"; OR "Lactobacillus"; OR "Candida"; OR "Tannerella forsythia"; OR "Treponema denticola"; OR "Fusobacterium nucleatum"; OR "Actimomyces actinomycetemcomitans"; OR "Prevotella intermedia", OR "Prevotella nigrescens"; OR "Porphyromonas gingivalis". Articles were previously selected by title and abstract. Articles that met the inclusion criteria were analyzed and classified as having low, moderate or high methodology quality. A new detailed checklist for quality assessment was developed based on the information required for applicable data extraction for reviews. The study design, sample, follow-up period, collection and microbial analysis methods, statistical treatment, results and discussion were assessed. Results: The initial search retrieved 305 articles of which 33 articles were selected by title and abstract. After full-text reading, 8 articles met the inclusion criteria, out of which 4 articles were classified as having low and 4 as moderate methodological quality. The moderate methodological quality studies were included in the systematic review. Conclusions: The literature revealed moderate evidence that the presence of fixed appliances influences the quantity and quality of oral microbiota. .

Objetivo: investigar se há evidências científicas para comprovar a hipótese de que a presença de aparelhos ortodônticos fixos influencia a microbiota bucal. Métodos: a busca por artigos foi realizada nas bases de dados do PubMed, ISI Web of Knowledge e Ovid, incluindo artigos publicados em inglês até 17 de maio de 2012. Esses deveriam relatar estudos observacionais humanos que apresentassem as palavras-chave: "aparelho ortodôntico fixo" e "colonização microbiológica"; ou "patógenos periodontais"; ou "Streptococcus"; ou "Lactobacillus"; ou "Candida"; ou "Tannerella forsythia"; ou "Treponema denticola"; ou "Fusobacterium nucleatum"; ou "Actimomyces actinomycetemcomitans"; ou "Prevotella intermedia"; ou "Prevotella nigrescens"; ou "Porphyromonas gingivalis". Artigos foram previamente selecionados pelo título e resumo. Artigos que atenderam aos critérios de inclusão foram analisados e classificados como de baixa, moderada ou alta qualidade metodológica. Uma nova lista de verificação detalhada para avaliação da qualidade foi desenvolvida, com base na informação necessária para a extração de dados aplicáveis para as revisões de literatura. O desenho do estudo, a amostra, o período de acompanhamento, coleta e métodos de análise microbiana, o tratamento estatístico, resultados e discussão foram avaliados. Resultados: a busca inicial encontrou 305 trabalhos. Em seguida, 33 artigos foram selecionados pelo título e resumo. Após a leitura do texto completo, apenas oito artigos preencheram os critérios de inclusão. Desses, quatro foram classificados como artigos com baixa qualidade metodológica e quatro como moderados. Os estudos de qualidade metodológica moderada foram incluídos na revisão sistemática. Conclusão: a literatura ...

Tomographic mapping of the hard palate and overlying mucosa

The aim of this study was to measure the thickness of the hard palate and its overlying mucosa using cone-beam computed tomography (CBCT), for purposes of miniscrew placement. The sample comprised 36 CBCT scans of patients aged 12 to 52 years from a database of the Orthodontics Department of the Federal University of Rio de Janeiro. Paracoronal views of the palatal region were reconstructed at 4, 8, 16 and 24 mm posterior to the incisive foramen. In each reconstruction measurements were taken at the suture, 3 mm and 6 mm bilaterally to it. Wilcoxon's test verified the differences between the selected regions. Total bone height decreased from the anterior to the posterior region. In cross sections 4, 16 and 24, bone height decreased from the suture laterally to the 3 mm region and then increased in the 6 mm region. The cortical thickness does not seem to be a concern because it presented a mean thickness of at least 1 mm at all sites evaluated. The measurements of the mucosa thickness decreased from lateral to median and from anterior to posterior regions. The most suitable areas for miniscrew placement in the palate are located 4 mm posterior to the incisive foramen, in the median or paramedian regions 3 mm adjacent to the suture.

Microbial colonization in orthodontic mini-implants

Peri-implant inflammation contributes for loss of secondary stability of orthodontic mini-implants. The investigation of microbial colonization in this area would benefit its control, and consequently favor the long-term success of mini-implants. Therefore, the aim of this study was to determine the establishment and the evolution of microbial colonization process in orthodontic mini-implants for 3 months, since the time of their installation. One-hundred and fifty samples collected from 15 mini-implants were investigated from baseline up to 3 months. The biological material was obtained from peri-implant area using paper points. Nonspecific, Streptococcus spp, Lactobacillus casei and Candida spp colonizations were analyzed by cell growth methods. Porphyromonas gingivalis colonization was observed by 16S rDNA-directed polymerase chain reaction. Data from cell growth were submitted to the Wilcoxon sign rank test and results from molecular analysis were presented in a descriptive way. There was no significant difference in the microbial colonization among the examined time intervals, except for Streptococcus spp, between baseline and 24 h, which characterized the initial colonization in this time interval. Lactobacillus casei and Candida spp colonizations were insignificant. No Porphyromonas gingivalis was detected among the analyzed samples. The microbial colonization of mini-implants did not significantly change during the study. However, it should be monitored by orthodontists, since it is an important factor for mini-implants success.

A inflamação peri-implantar contribui para a perda da estabilidade secundária dos mini-implantes ortodônticos. A investigação da colonização microbiana desta área beneficiaria o seu controle e, consequentemente, favoreceria o sucesso dos mini-implantes a longo prazo. Portanto, o objetivo dos autores foi determinar o estabelecimento e evolução do processo de colonização microbiana em mini-implantes ortodônticos por três meses desde a instalação. Cento e cinquenta amostras coletadas de 15 mini-implantes foram investigadas desde o tempo inicial até 3 meses. O material biológico foi obtido da área peri-implantar com auxílio de cones de papel absorvente. As colonizações inespecíficas de Streptococcus spp, Lactobacillus casei e Candida spp foram analisadas por métodos de crescimento celular. A colonização por Porphyromonas gingivalis foi observada por meio da reação em cadeia da polimerase 16S rDNA. Os dados do crescimento celular foram submetidos ao teste de Wilcoxon sign rank e os resultados da biologia molecular foram apresentados de modo descritivo. Não houve diferença estatisticamente significante da colonização microbiana entre os intervalos de tempo avaliados, exceto para Streptococcus spp entre os tempos inicial e 24 h, o que caracterizou o início da colonização neste intervalo de tempo. As colonizações por Lactobacillus casei e Candida spp foram insignificantes. Não foi detectada a presença de Porphyromonas gingivalis nas amostras analisadas. A colonização microbiana nos mini-implantes não se alterou significativamente durante o estudo. No entanto, deve ser monitorada por ortodontistas, uma vez que é um fator importante para o sucesso dos mini-implantes.

Frictional resistance of orthodontic wires tied with 3 types of elastomeric ligatures

The aims of this study were to determine and compare frictional resistance obtained by low-friction and conventional elastomeric ligatures in the presence of artificial saliva, and observe whether this variable changed after 21 days. Super Slick® low-friction elastomeric ligatures and conventional ligatures of the brands TP conventional® and Unitek® were placed on standard edgewise maxillary central incisor metal brackets, slot .022" × .028" tying rectangular orthodontic wires .018" × .025". Three experimental groups were arranged according to the type of ligature and a control group in which no wires were used. The friction values obtained between the bracket/wire/ligature set were measured using a Universal Test Machine at a speed of 20 mm/minute, at two experimental time intervals: T0 - immediately after specimen fabrication; and T1 - 21 days after fabrication and immersion in artificial saliva at 37 ºC. Conventional Unitek ligatures and the low-friction ligature (Super Slick) showed the lowest friction values at T0. After 21 days (T1), however, conventional Unitek ligatures presented the lowest value. All groups assessed from T0 to T1 showed a numerical reduction in friction values, suggesting that time, heat and humidity may cause elastic degradation, however this was not verified statistically (P > 0.05).