Analysis of Estrogen Effects on Eruption of Rat Molars / Análisis de los Efectos del Estrógeno en la Erupción de Molares de Rata

ABSTRACT: Tooth eruption requires resorption of the alveolar bone interposed between the tooth germ and the oral mucosa (coronal bone). The cells responsible for bone resorption are the osteoclasts and their activity can be reduced or inactivated by estrogen hormone. We aimed to investigate the effects of estrogen on the process of tooth eruption in rats. Thirty-three Wistar rats, aged two-to-17-days, were divided into control, sham and estrogen-treated groups. After daily injections with estrogen, the animals were euthanized and the jaws removed and processed for histological analysis. We performed clinical examination, morphological analysis, quantification of the number of osteoclasts on the surface of the coronal bone and immunohistochemical analysis of estrogen receptor type alpha (ERα). Estrogen therapy was effective, which could be confirmed by the higher estrogen plasma levels on treated animals. However, it had no effect on tooth development or tooth eruption. Progressive bone resorption was observed and the number of osteoclasts on coronal bone was not affected on hormoneinjected animals, allowing tooth to erupt at the same time observed in untreated animals. Immunohistochemistry for ERα confirmed the presence of this type of receptor in osteoclasts, osteoblasts and osteocytes. Taken together, our results showed that estrogen stimulation was not sufficient to decrease the number of osteoclasts on the coronal bone, supporting the idea that, although estrogen may have a protective activity on bone resorption, this may not apply to the alveolar bone that is meant to be resorbed during eruptive process.

RESUMEN: La erupción dental requiere la resorción del hueso alveolar interpuesto entre el germen dental y la mucosa oral (hueso coronal). Las células responsables de la resorción ósea son los osteoclastos y su actividad puede reducirse o inactivarse por la hormona del estrógeno. Objetivos: apuntamos a investigar los efectos del estrógeno en el proceso de la erupción dental en ratas. Treinta y tres ratas Wistar, de dos a 17 días de edad, se dividieron en grupos de control, Sham y se trataron con estrógenos. Los animales fueron eutanizados después del tratamento con estrógeno y se procesaron las mandíbulas para el análisis histológico. Se realizó el examen clínico, el análisis morfológico, la cuantificación del número de osteoclastos en la superficie del hueso coronal y el análisis inmunohistoquímico del tipo de receptor de estrógeno alfa (ERα). La terapia de estrógeno fue eficaz, lo que podría ser confirmado por los niveles plasmáticos más altos de estrógeno en los animales tratados. Sin embargo, no se observó ningún efecto sobre el desarrollo de los dientes o la erupción dental. Se observó una resorción ósea progresiva y el número de osteoclastos en el hueso coronal no se vio afectado en los animales inyectados con hormonas, permitiendo que el diente erupcionó durante el mismo período de tiempo observado en animales no tratados. La inmunohistoquímica para el ERα confirmó la presencia de este tipo de receptor en los osteoclastos, osteoblastos y osteocitos. Nuestros resultados mostraron que la estimulación del estrógeno no fue suficiente para reducir el número de osteoclastos en el hueso coronal confirmando que, si bien el estrógeno puede tener una actividad protectora en la resorción ósea, esto puede no se aplica al hueso alveolar que está destinado a ser rerecurrido durante el proceso eruptivo.

Avaliação digital tridimensional da movimentação dentária com alinhadores transparentes / Three-dimensional digital assessment of tooth movement with transparent aligners

O objetivo deste estudo foi avaliar a concordância das medidas obtidas em modelos sobrepostos em dois programas com as medidas propostas pelo software ClinCheck; além de avaliar a eficácia da movimentação dentária obtida por alinhadores dentários, por meio de sobreposições de modelos digitais. Sete pacientes foram submetidos a tratamento ortodôntico com o sistema Invisalign. Os modelos digitais iniciais e finais fornecidos pela Align Technology foram sobrepostos nos programas 3D Slicer 4.6.2 e GOM Inspect 2017 para mensurar as movimentações dentárias e comparar com as que foram propostas pelo software ClinCheck; os modelos iniciais e finais obtidos clinicamente foram digitalizados e sobrepostos no software GOM Inspect 2017 para mensurar os movimentos dentários obtidos clinicamente e comparar com as medidas propostas pelo software ClinCheck. Posteriormente, os dados das sobreposições dos modelos iniciais e finais fornecidos pelo Align Technology foram comparados pela Análise de Concordância de BlandAltman. No programa GOM Inspect 2017, houve concordância em dois dos seis movimentos avaliados; já no programa 3D Slicer 4.6.2, foi encontrada concordância em três dos seis movimentos. Já os dados das sobreposições dos modelos iniciais e finais obtidos clinicamente foram comparados pelo teste de Wilcoxon. Os movimentos de extrusão, translação vestibular e translação mesial na maxila não apresentaram diferença estatisticamente significativa. Todos os movimentos na mandíbula e os movimentos de intrusão, translação lingual e translação distal na maxila apresentaram diferença estatisticamente significante. Apesar de clinicamente a diferença encontrada entre os softwares analisados e o ClinCheck ser desprezível, não podemos substituir o ClinCheck por outros softwares. Desta forma, para substituir um método por outro, o ideal seria que todas as análises apresentassem concordância com o software ClinCheck. Já para a comparação da movimentação dentária obtida clinicamente com a que foi proposta pela Align Technology, percebemos que movimentos dentários na mandíbula são imprecisos. Os movimentos de extrusão, translação vestibular e translação mesial na maxila foram identificados como precisos. As diferenças obtidas foram clinicamente desprezíveis considerando os movimentos isolados, mas significantes quando consideramos todos os movimentos propostos para um grupo de dentes. (AU)

The aim of this study was to evaluate the agreement of measures obtained by superimposition of models in two different programs with the measures proposed by the ClinCheck software; besides evaluating the efficacy of tooth movement obtained by dental aligners, through superimposition of digital models. Seven patients underwent orthodontic treatment with the Invisalign system. The initial and final digital models provided by Align Technology were superimposed on 3D Slicer 4.6.2 and GOM Inspect 2017 software to measure dental movements and compare with those proposed by the ClinCheck software; the initial and final models clinically obtained were digitized and superimposed on the GOM Inspect 2017 software to measure clinically obtained dental movements and compare with the measures proposed by the ClinCheck software. Subsequently, the superimposition data of the initial and final models provided by Align Technology were compared by the Bland-Altman Concordance Analysis. In the GOM Inspect 2017 software, there was agreement in two of the six movements evaluated; nevertheless, in the 3D Slicer 4.6.2 program, concordance was found in three of the six movements. The superimposed data of the initial and final models obtained clinically were compared by the Wilcoxon test. The movements of extrusion, vestibular translation and mesial translation in the maxilla did not present a statistically significant difference. All mandible tooth movements and the movements of intrusion, lingual translation and distal translation in the maxilla presented a statistically significant difference. Although clinically the difference found between the analyzed software and ClinCheck is negligible, we can not replace ClinCheck with other software. Thus, to substitute one method for another, ideally all analyzes would agree with ClinCheck software. In order to compare the dental movement obtained clinically with that proposed by Align Technology, we noticed that dental movements in the mandible are imprecise. The movements of extrusion, vestibular translation and mesial translation in the maxilla were identified as accurate. The differences obtained were clinically negligible considering the isolated movements, but significant when considering all the proposed movements for a group of teeth. (AU)

Mini-implant selection protocol applied to MARPE.

INTRODUCTION: Rapid maxillary expansion (RME) is the therapy of choice to correct skeletal transverse dimension in children and adolescents, associating orthopedic and dental effects. In an attempt to prevent the undesirable dentoalveolar effects and optimize the potential of skeletal expansion in individuals in advanced stages of skeletal maturation, the miniscrew-assisted rapid palatal expander (MARPE) was proposed by Lee et al. in 2010. OBJECTIVE: This paper presents a systematized protocol for selection of miniscrews indicated for MARPE, by the evaluation of cone-beam computed tomographies (CBCT). Variables related with the bone and soft tissue thicknesses at the palatal regions of interest, as well as in relation to the fixation rings of miniscrews of the palatal expander are analyzed and discussed to provide better performance in the clinical practice.

Mini-implant selection protocol applied to MARPE

Abstract Introduction: Rapid maxillary expansion (RME) is the therapy of choice to correct skeletal transverse dimension in children and adolescents, associating orthopedic and dental effects. In an attempt to prevent the undesirable dentoalveolar effects and optimize the potential of skeletal expansion in individuals in advanced stages of skeletal maturation, the miniscrew-assisted rapid palatal expander (MARPE) was proposed by Lee et al. in 2010. Objective: This paper presents a systematized protocol for selection of miniscrews indicated for MARPE, by the evaluation of cone-beam computed tomographies (CBCT). Variables related with the bone and soft tissue thicknesses at the palatal regions of interest, as well as in relation to the fixation rings of miniscrews of the palatal expander are analyzed and discussed to provide better performance in the clinical practice.

Resumo Introdução: a expansão rápida da maxila (ERM) é a terapia de escolha para a correção da dimensão transversa esquelética em crianças e adolescentes, associando-se efeitos ortopédicos e dentários. Com a finalidade de prevenir os efeitos dentoalveolares indesejáveis e otimizar o potencial de expansão esquelética em indivíduos com estágios avançados de maturação esquelética, a técnica de expansão rápida da maxila assistida por mini-implantes (MARPE) foi proposta por Lee e colaboradores em 2010. Objetivo: o presente estudo apresenta um protocolo sistematizado para seleção de mini-implantes indicados para a MARPE, mediante avaliação de imagens de tomografia computadorizada de feixe cônico (TCFC). Variáveis relacionadas à espessura de tecido ósseo e tecido mole nas regiões de interesse do palato, bem como em relação ao anel de fixação dos mini-implantes do parafuso expansor, são analisadas e discutidas para proporcionar melhor desempenho na prática clínica.