External root resorption evaluated by CBCT 3D models superimposition.

INTRODUCTION: The literature reports the association of external root resorption (ERR) with orthodontic movement. In cases of premolars extractions, orthodontic movement of anterior teeth is usually quite expressive, which are precisely the most susceptible teeth to suffer from ERR. OBJECTIVE: The aim of this study was to assess the root morphology of maxillary canines and incisors in patients submitted to four premolar extraction and orthodontic retraction of the anterior teeth, by means of 3D surface models superimposition and mapping. METHODS: The sample consisted of six adult patients, five female and one male, with a mean age of 23.5 ± 6.5 years, who underwent orthodontic treatment. All patients presented bimaxillary dental protrusion, with indication of maxillary and mandibular first premolar extractions, followed by the retraction of anterior teeth and space closure. Cone beam CT scans were performed before the beginning of the treatment (T0) and right after space closure (T1). 3D models were built at both times and superimposed to identify the root changes for the given period. RESULTS: All average differences were close to zero and, even when evaluating the extreme values, the observed changes were always smaller than the accuracy of the CBCT. CONCLUSION: A mild resorption trend was observed, although it was not clinically significant, with values lower than the tomography accuracy.

Do low-cost 3-dimensional printers produce suitable dental models?

INTRODUCTION: When choosing a 3-dimensional printer for dental models, the cost-benefit ratio should be evaluated. The purpose of this study was to evaluate the accuracy, precision, cost, and time taken to prepare and print using different low-cost techniques (2 digital light processing [DLP] and 1 fused filament fabrication [FFF] printer) compared with the reference proven to be clinically accepted (PolyJet). METHODS: For this purpose, the upper and lower virtual models of 5 patients were printed using: (1) DLP printer Moonray, (2) DLP printer Anycubic, (3) DLP printer Moonray with Anycubic resin, (4) Filament printer UpMini 2 (FFF), and (5) Polyjet printer Objet Eden500V. One of the virtual models was also printed 4 consecutive times on each printer to allow consistency assessment. Afterward, the 14 printed resin models were scanned, and their accuracy was evaluated by model superimposition using Geomagic Qualify software (3D Systems, Rock Hill, SC). A digital caliper was also used to obtain linear measurements. All measurements were carried out by a calibrated examiner. RESULTS: The results showed that all printers produced similar results, although Moonray with Anycubic resin showed loss of accuracy and Anycubic showed inconsistent vertical dimensions. The printing cost and time consumed from each pair of models were calculated for the overall printing process, analyzing which would have the best cost-benefit ratio. CONCLUSIONS: Polyjet printing was considered the fastest method but with the highest cost. FFF printing was the lowest printing and input cost but was considerably more time-consuming. There was a balance in both DLP printers, and they were considered the best cost-benefit ratio for small independent dental offices.

External root resorption evaluated by CBCT 3D models superimposition

ABSTRACT Introduction: The literature reports the association of external root resorption (ERR) with orthodontic movement. In cases of premolars extractions, orthodontic movement of anterior teeth is usually quite expressive, which are precisely the most susceptible teeth to suffer from ERR. Objective: The aim of this study was to assess the root morphology of maxillary canines and incisors in patients submitted to four premolar extraction and orthodontic retraction of the anterior teeth, by means of 3D surface models superimposition and mapping. Methods: The sample consisted of six adult patients, five female and one male, with a mean age of 23.5 ± 6.5 years, who underwent orthodontic treatment. All patients presented bimaxillary dental protrusion, with indication of maxillary and mandibular first premolar extractions, followed by the retraction of anterior teeth and space closure. Cone beam CT scans were performed before the beginning of the treatment (T0) and right after space closure (T1). 3D models were built at both times and superimposed to identify the root changes for the given period. Results: All average differences were close to zero and, even when evaluating the extreme values, the observed changes were always smaller than the accuracy of the CBCT. Conclusion: A mild resorption trend was observed, although it was not clinically significant, with values lower than the tomography accuracy.

RESUMO Introdução: A literatura relata a associação de reabsorção radicular externa (RRE) com a movimentação ortodôntica. Nos casos de extrações de pré-molares, a movimentação ortodôntica costuma ser bastante expressiva nos dentes anteriores, que são justamente os dentes mais suscetíveis à RRE. Objetivo: O objetivo do presente estudo foi avaliar a morfologia radicular de caninos e incisivos superiores em pacientes submetidos à extração de quatro pré-molares e retração ortodôntica dos dentes anteriores, por meio da sobreposição e mapeamento de modelos 3D. Métodos: A amostra foi composta por seis pacientes adultos, cinco do sexo feminino e um do masculino, com média de idade de 23,5 ± 6,5 anos, submetidos a tratamento ortodôntico. Todos os pacientes apresentavam biprotrusão dentária, com indicação de extração dos primeiros pré-molares superior e inferior, seguida de retração dos dentes anteriores e fechamento do espaço. A tomografia computadorizada de feixe cônico (TCFC) foi realizada antes do início do tratamento (T0) e logo após o fechamento de espaços (T1). Modelos 3D foram construídos em ambos os momentos e sobrepostos para identificar as mudanças nas raízes dentárias no período determinado. Resultados: Todas as médias das diferenças foram próximas de zero e, mesmo avaliando os valores extremos, as mudanças observadas foram sempre menores que a sensibilidade da TCFC. Conclusão: Observou-se tendência de leve reabsorção, embora não clinicamente significativa, com valores inferiores à sensibilidade tomográfica.