Use of auxiliary devices during retreatment of direct resin composite veneers.

The removal of direct composite veneers, when the retreatment is necessary, represents a challenge to the clinician, since the healthy dental structure must be preserved. Thus, the aim of this study was to compare the accuracy provided by different auxiliary devices during retreatment of direct composite veneers. Seventy-five bovine teeth were prepared for direct composite veneers, scanned (T1), and restored. Specimens were divided into 5 groups for retreatment: conventional high-speed handpiece without auxiliary device (WD); high-speed handpiece with a white LED (WL); high-speed handpiece with an UV light (UL); electric motor and multiplier 1/5 handpiece (EM); and conventional high-speed handpiece using magnifying loupe (ML). After retreatments, other scanning was performed (T2). Changes on dental wear or composite residues areas, as well as, the average between wear and presence of residues were measured. Data were submitted to Kruskal-Wallis and Dunn's post-test (p≤ 0.05). There were greater areas of wear for ML, being statistically superior to WD and EM groups. The ML presented smaller residues areas, being statistically lower than the WD and EM groups. Regarding the average between wear and the presence of resin residues, additional wear occurred after re-preparation, regardless of the group. Magnifying loupe promoted greater areas of wear and smaller areas of resin residues than conventional high-speed handpiece and electric motor. Both techniques using light accessories did not differ from other ones.

Efeito do uso de dispositivos auxiliares na precisão do retratamento de facetas diretas / Effect of the use of auxiliary devices on the accuracy of retreatment of direct veneers

A remoção de facetas de resina composta quando o retratamento se faz necessário representa um desafio ao clínico no sentido de preservação do remanescente dental. Sendo assim, o objetivo deste estudo foi avaliar dispositivos auxiliares na precisão dos retratamentos de facetas diretas, por meio de escaneamento digital. Setenta e cinco espécimes de dente bovino (10 x 8 mm ­ cor A1) foram selecionados, e então foi realizado o escaneamento inicial (T0). Em seguida, os espécimes foram preparados para faceta de resina composta e novamente escaneados (T1) para verificação da padronização dos preparos. As superfícies dentárias foram então restauradas com sistema adesivo e resina composta. Os espécimes foram divididos em 5 grupos (n=15): remoção sem dispositivo auxiliar (CN ­ grupo controle), remoção com alta rotação com LED branco (AL), remoção com alta rotação com luz ultra-violeta (UV), remoção com motor elétrico e multiplicadora 1/5 (MT) e remoção com uso de lupa de aumento 2,5x (MN). A remoção das facetas e o re-preparo dos espécimes foi feito por outro operador, sendo então realizado um novo escaneamento (T2). A alteração volumétrica entre T2 e T1, assim como, as áreas de desgaste dentário e/ou presença de resíduos de resina composta foram avaliados. A média entre desgaste e presença de resíduos entre T2 e T1 foi também realizada. Os dados foram submetidos aos testes estatísticos de Kruskal-Wallis e pós teste de Dunn ao nível de significância de 5%. Não foi encontrada diferença estatística entre os grupos entre T1 e T0, com uma média de desgaste de 0,28 mm (± 0,07), p ≥ 0.05. Somente houve diferença entre os grupos para as análises referentes às áreas de desgaste e de presença de resíduos (p ≤ 0,05). Ocorreu maiores áreas de desgaste para o grupo MN, sendo estatisticamente superior aos grupos CN e MT (p≤ 0,05). O oposto ocorreu para áreas de resíduos, sendo que o grupo MN apresentou as menores áreas de resíduos, sendo estatisticamente inferior aos grupos CN e MT (p≤ 0,05). Considerando a média entre desgaste e resíduos, ocorreu um desgaste adicional após o re-preparo, indepedente do grupo (p≥ 0,05). Apesar do uso de lupa odontológica ser mais efetivo para remoção da resina composta durante o retratamento de faceta direta, este proporciona maior desgaste da estrutura dentária. A similaridade da fluorescência entre a resina composta e o substrato dentário minimizou os benefícios do dispositivo com luz UV(AU)

The removal of direct composite veneers when the retreatment is necessary represents a challenge to the clinician in the sense of dental preservation. Thus, the aim of this study was to evaluate auxiliary devices, in the precision of direct composite veneers retreatments, through digital scanning. Seventy-five bovine tooth specimens (10 x 8 mm - A1 shade) were selected and the initial scanning (T0) was performed. Then, the specimens were prepared for direct composite veneer and rescanned (T1) to verify the standardization of the preparations. The dental surfaces were then restored with adhesive system and composite resin. The specimens were divided into 5 groups (n=15): removal without auxiliary device (CN - control group), removal with a hand piece with a white LED (WL), removal with a hand piece with an UV light source (UV), removal with electric motor and multiplier 1/5 hand piece (MT); and removal with the use of a 2.5x dental loupe (MN). The removal of the restorations and the re-preparation of the specimens were done by another operator, and a new scanning (T2) was performed. The volumetric change between T2 and T1, as well as the areas of additional dental wear and presence of composite resin residues were evaluated. The mean considering additional wear and the presence of residues between T2 and T1 were also performed. The data were submitted to Kruskal-Wallis and Dunn's as post-test, at significance level of 5%. No statistical difference among the groups were found between T1 and T0 with a wear mean of 0.28 mm (±0.07), p≥ 0.05. There were only statistical differences between the groups for the analyses related to the areas of wear and presence of residues (p≤ 0.05). There were greater areas of wear for MN group, being statistically superior to CN and MT groups (p≤ 0.05). The opposite occurred for areas of presence of residues, with the MN group presenting smaller areas of residues, being statistically lower than the CN and MT groups (p≤ 0.05). Considering the average between wear and residues, additional wear occurred after re-preparation, regardless of the group (p≥ 0.05). Although the use of dental loupe is more effective for removal of composite resin during the retreatment of direct composite veneers, it provides greater wear of the dental structure. The fluorescence similarity between the composite resin and the dental substrate minimized the benefits of UV light device(AU)