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Abstract The aim of study was to evaluate periodontal conditions of upper canines and second premolars with and without proximal contact of individuals undergoing orthodontic treatment associated to extractions of the upper first premolars. The study selected upper canines and premolars of individuals undergoing orthodontic treatment without extractions (30 hemiarches - control group), or with extraction of the upper first premolars and whose canines and second premolars had interproximal contact (16 hemiarches - group 1) or diastema (17 hemiarches - group 2). Clinical (plaque index, probing depth, gingival bleeding index, height of the gingival margin, clinical attachment loss and gingival clefts) and radiographic (crest height, bone height and bone-crest discrepancy) parameters of the distal surfaces of canines and mesial surfaces of premolars were evaluated. Group 1 had worse results when compared to the control group for the levels of plaque in canines and premolars and for probing depth in canines (distal and mean) and in premolars (lingual and mean), as well as increasing tendency of clinical attachment loss (lingual and mean) in premolars. Plaque level in canines in group 1 was also significantly higher than in group 2. There was no difference between group 2 and the control group. The lack of proximal contact between canines and second premolars did not significantly affect their periodontal characteristics.

Resumo A extração de dentes para obtenção de espaço nos arcos dentários é uma estratégia rotineiramente utilizada em Ortodontia, porém a movimentação de dentes para os locais de extrações pode estar associada à falhas na estabilidade dos dentes e abertura do ponto de contato, gerando prejuízo aos tecidos periodontais. Objetivo: Avaliar a condição periodontal de caninos e segundos pré-molares superiores com e sem ponto de contato entre si de indivíduos submetidos ao tratamento ortodôntico associado à extração dos primeiros pré-molares superiores. Foram selecionados caninos, primeiros e segundos pré-molares superiores de indivíduos submetidos ao tratamento ortodôntico sem extração (30 hemiarcos - grupo controle) ou com extração dos primeiros pré-molares superiores cujos caninos e os segundos pré-molares apresentavam contato interproximal (16 hemiarcos - grupo 1) ou diastema (17 hemiarcos - grupo 2). Nas superfícies distal dos caninos e mesial dos pré-molares foram avaliados parâmetros clínicos e radiográficos para determinar o efeito da movimentação dos dentes para o local de extração e da ausência de ponto de contato interproximal nos tecidos periodontais. Os grupos não apresentaram diferença significativa para a idade e o tempo de pós-tratamento. O grupo 1 apresentou valores mais desfavoráveis em relação ao grupo controle para o índice de placa em caninos e pré-molares e para a profundidade de sondagem em caninos (distal e média) e em pré-molares (lingual e média), além de uma tendência de maior perda de inserção clínica (lingual e média) nos pré-molares. O índice de placa nos caninos do grupo 1 também foi significativamente maior do que no grupo 2. Os grupos 2 e controle não apresentaram diferença significativa. A ausência de ponto de contato entre os caninos e os segundos pré-molares superiores não afetou significativamente a situação periodontal desses dentes.

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The aim of study was to evaluate periodontal conditions of upper canines and second premolars with and without proximal contact of individuals undergoing orthodontic treatment associated to extractions of the upper first premolars. The study selected upper canines and premolars of individuals undergoing orthodontic treatment without extractions (30 hemiarches - control group), or with extraction of the upper first premolars and whose canines and second premolars had interproximal contact (16 hemiarches - group 1) or diastema (17 hemiarches - group 2). Clinical (plaque index, probing depth, gingival bleeding index, height of the gingival margin, clinical attachment loss and gingival clefts) and radiographic (crest height, bone height and bone-crest discrepancy) parameters of the distal surfaces of canines and mesial surfaces of premolars were evaluated. Group 1 had worse results when compared to the control group for the levels of plaque in canines and premolars and for probing depth in canines (distal and mean) and in premolars (lingual and mean), as well as increasing tendency of clinical attachment loss (lingual and mean) in premolars. Plaque level in canines in group 1 was also significantly higher than in group 2. There was no difference between group 2 and the control group. The lack of proximal contact between canines and second premolars did not significantly affect their periodontal characteristics.

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INTRODUCTION: This study aimed to simulate the different positions of the hyrax appliance expander screw and evaluate tooth displacement and the stress distribution standard on the periodontal ligament using the finite element method. METHODS: Part of the maxilla with anchorage teeth, periodontal ligament, midpalatal suture, and the hyrax appliance was modeled, and finite element method models were created to simulate 6 different screw positions. There were 2 vertical positions at distances of 20 mm and 15 mm from the occlusal plane. Another position was anteroposterior, the center of the screw placed between and equidistant from the mesial face of the first molar and the distal face of the first premolar, aligned to the center of the crown of the first molar, with the anterior edge of the screw aligned to the distal face of the first molar. A 1 mm activation of the expander screw was simulated. The displacement (total, vertical, and buccolingual) and the stress distribution on the periodontal ligament of supporting teeth in each model were registered. RESULTS: The model simulating the expander screw in a more occlusal and anterior position presented higher displacement values and higher stress concentration, followed by the model with the screw in a more posterior but same vertical position. With the exception of the first premolar, the teeth presented cervical-apical displacement in the vestibular face and apical-cervical displacement in palatal faces. This displacement is compatible with the vestibular inclination associated with the activation of the expander screw. The first premolar presented an atypical tendency for the mesial and lingual displacement of the vestibular surface and counterclockwise rotation. CONCLUSIONS: The supporting teeth presented a tendency for vestibular crown displacement and lingual root displacement associated with compression areas in the vestibular-cervical region and tensile strength in the linguoapical region. Placing the expander screw in a more occlusal and anterior position generated more mechanical stress transfer, resulting in greater dental displacement.

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INTRODUCTION: Our objective was to evaluate the stress and deformation distribution patterns on the maxillary bone structure using the finite element method by simulation of different vertical and anteroposterior positions of the expansion screw on the hyrax expander appliance. METHODS: Part of the maxilla with anchorage teeth, midpalatal suture, and the hyrax appliance were modeled, and 6 distinct finite element method models were created to simulate different positions of the expansion screw. There were 2 vertical positions at distances of 20 and 15 mm from the occlusal plane. Another 3 positions were anteroposterior, with the center of the screw placed between and equidistant from the mesial face of the first molar and the distal face of the first premolar, aligned to the center of the crown of the first molar, and the anterior edge of the screw aligned to the distal face of the first molar. The initial activations of the expanders were simulated, and the stress distributions on the maxilla in each model were registered. RESULTS: The stress was concentrated in the anterior region of the models, close to the incisive foramen, dissipating through the palate in the posterior and lateral orientations, in the direction of the pterygoid pillar, diverting from the midpalatal suture region. When the expander screw was simulated closer to the occlusal plane and in a more anterior position, more stress was located around the incisive foramen and distributed through the midpalatal suture to its posterior portion. More posterior positions resulted in concentrated stress around the pterygoid pillars. At all simulations, the midpalatal suture showed a V-shaped expansion, with the vertex superior in the coronal view and posterior in the axial view. CONCLUSIONS: Different positions of the expander screw interfered with stress intensity and distribution patterns. When the expansion screw was simulated in a more occlusal and anterior position, it was more efficient to transfer the mechanical effects from the appliance to the bone structures.

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PURPOSE: To determine the effect of field of view (FOV) size on gray values in cone beam computed tomography (CBCT) and multislice computed tomography (MSCT) images. MATERIAL AND METHODS: A phantom made up of 3 cylinders containing distilled water, plaster, and motor oil was constructed and inserted into an acrylic cylinder filled with distilled water. The phantom was scanned with a CBCT and MSCT device using 3 FOV sizes. Gray value of each material was evaluated in 40 axial slices, and the comparison between the results obtained with the same FOV size was made. RESULTS: In CBCT examinations, there was significant difference between the gray values of different FOVs for the 3 materials. In the MSCT, there was significant difference for the oil. Gray values showed significant difference between the CBCT and MSCT examinations for the 3 materials in the 3 different FOV sizes. CONCLUSIONS: Gray values determined in CBCT images are significantly influenced by the FOV size. Although the gray values obtained in MSCT have shown statistically significant differences between some acquisitions, the analysis of those differences seems to indicate low clinical relevance.

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BACKGROUND: Pain, a common experience reported by patients under orthodontic treatment, results from force application to the teeth and trauma caused by attrition of brackets and wires against the underlying oral mucosa. The main protection of the mucosa is secretory immunoglobulin A (sIgA), which may play a fundamental role in integrity maintenance and whose production may be reduced as a result of the stress of orthodontic treatment. The aim of this study was to assess sIgA levels in the saliva and their correlation with oral pain intensity in adults and children after the installation of fixed orthodontic appliances. MATERIAL/METHODS: Twenty patients (10 children, age 11-13 years; 10 adults, age 18-37 years) were assessed before treatment, after bracket bonding, and after initial arch wire insertion. Saliva was sampled for sIgA analysis, and oral pain was assessed through a visual analog scale. RESULTS: Although there was a trend toward reduction of the salivary sIgA levels during the initial arch phase in the children, and during the bonding and initial arch phases in the adults, this finding was not significant. CONCLUSIONS: There was a trend toward a negative correlation of oral pain intensity and salivary sIgA levels in the children, which may indicate the importance of sIgA for oral protection during orthodontic treatment, interfering with the pain experienced by the patients.

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