Surface Topography, Gloss and Flexural Strength of Pressable Ceramic After Finishing-Polishing Protocols.

This study evaluated the effect of different finishing-polishing protocols on surface roughness, gloss, morphology and biaxial flexural strength of pressable fluorapatite glass ceramic. Thirty ceramic discs (12x1 mm) were produced and divided into five groups (n=6): CT: control (glaze); DA: fine grit diamond bur; DG: DA + new glaze layer; DP: DA + felt disk with fine grit diamond paste; DK: DA+ sequential polishing with silicon abrasive instruments, goat hair brush and cotton wheel. The specimens were analyzed for surface roughness (Ra) under profilometry and atomic force microscopy (AFM). Gloss was measured with spectrophotometry and micromorphology with scanning electron microscopy (SEM). Flexural strength was assessed by biaxial flexural strength test. Data were analyzed using one-way ANOVA and Tukey's post hoc test (a=0.05). DK showed the lowest surface roughness values and DA presented the highest in the perfilometer analysis. No significant differences were observed in the AFM for the CT, DG and DK groups, which presented the lower surface roughness; DA and DP had the higher Ra values. The DA, DP and CT showed the lowest surface gloss values, and the reflectance was significantly different from those observed for DK and DG groups. SEM analysis revealed the smoothest surface for DK group, followed by DG and CT groups; DA and DP groups exhibited variable degrees of surface irregularities. No significant differences were observed among groups for the biaxial flexural strength. The polishing protocol used in DK group can be a good alternative for chairside finishing of adjusted pressable fluorapatite glass ceramic surfaces.

Surface topography, gloss and flexural strength of pressable ceramic after finishing-polishing protocols

Abstract This study evaluated the effect of different finishing-polishing protocols on surface roughness, gloss, morphology and biaxial flexural strength of pressable fluorapatite glass ceramic. Thirty ceramic discs (12x1 mm) were produced and divided into five groups (n=6): CT: control (glaze); DA: fine grit diamond bur; DG: DA + new glaze layer; DP: DA + felt disk with fine grit diamond paste; DK: DA+ sequential polishing with silicon abrasive instruments, goat hair brush and cotton wheel. The specimens were analyzed for surface roughness (Ra) under profilometry and atomic force microscopy (AFM). Gloss was measured with spectrophotometry and micromorphology with scanning electron microscopy (SEM). Flexural strength was assessed by biaxial flexural strength test. Data were analyzed using one-way ANOVA and Tukey's post hoc test (a=0.05). DK showed the lowest surface roughness values and DA presented the highest in the perfilometer analysis. No significant differences were observed in the AFM for the CT, DG and DK groups, which presented the lower surface roughness; DA and DP had the higher Ra values. The DA, DP and CT showed the lowest surface gloss values, and the reflectance was significantly different from those observed for DK and DG groups. SEM analysis revealed the smoothest surface for DK group, followed by DG and CT groups; DA and DP groups exhibited variable degrees of surface irregularities. No significant differences were observed among groups for the biaxial flexural strength. The polishing protocol used in DK group can be a good alternative for chairside finishing of adjusted pressable fluorapatite glass ceramic surfaces.

Resumo O objetivo deste estudo foi avaliar o efeito de diferentes protocolos de acabamento e polimento na rugosidade da superfície, brilho, resistência à flexão biaxial e morfologia de cerâmica prensada. Trinta discos de cerâmica (12x1 mm) foram produzidos e divididos em cinco grupos (n=6): CT- controle (glaze); DA- ponta diamantada de granulação fina; DG: DA + nova camada de glaze; DP: DA + disco de feltro com pasta de diamante de granulo fino; DK: DA + polimento sequencial com instrumentos abrasivos de silício, escova de cabra e roda de algodão. Os espécimes foram analisados quanto à rugosidade da superfície (Ra) sob profilometria e microscopia de força atômica (AFM). O brilho foi medido com espectrofotometria e a micromorfologia com microscopia eletrônica de varredura (SEM). A resistência à flexão foi avaliada pelo teste de resistência à flexão biaxial. Os dados foram analisados ​​usando ANOVA um fator e teste post hoc de Tukey (a=0,05). DK mostrou mais baixos valores de rugosidade da superfície e DA apresentou o maior na análise do perfilômetro. Não foram observadas diferenças significativas no AFM para os grupos CT, DG e DK, que apresentaram a menor rugosidade de superfície; DA e DP apresentaram os maiores valores Ra. O DA, DP e CT mostraram valores de brilho superficial mais baixos, e a reflectância foi significativamente diferente da observada para os grupos DK e DG. A análise de SEM revelou a superfície mais homogênea para o grupo DK, seguido de grupos DG e CT; Os grupos DA e DP exibiram graus variáveis de irregularidades da superfície. Não foram observadas diferenças significativas entre os grupos quanto à resistência à flexão biaxial. O protocolo de polimento utilizado no grupo DK pode ser uma boa alternativa para o acabamento em consultório das superfícies de cerâmicas prensadas após ajustes.

A multidisciplinary direct restorative approach for recovering crown-root fractures in young patients: a case report / Tratamento multidisciplinar restaurador direto para reabilitação de fraturas corono-radiculares em pacientes jovens: relato de caso

The aim of this article is to describe a step-by-step protocol for emergency care of a young patient with multidisciplinary direct restorative approach for recovering crown-root fractures. Fractures of maxillary incisors are a frequent consequence of trauma in children and teenagers. Glass fiber post associated with composite resin restoration represents a conservative approach for this rehabilitation. This paper presents a case of a 14-year-old male patient with a crown-root fracture in a left maxillary lateral incisor. The patient was submitted to a periodontal surgery for coronal lengthening. After that, the post luting and restoration technique was performed. Finally, a mouthguard was made for preventing new trauma. The multidisciplinary treatment described for crown-root fracture rehabilitation is simple, providing esthetics and function with a conservative approach in younger patients.

O objetivo deste artigo é descrever passo a passo, um protocolo para tratamento de emergência de pacientes jovens, com abordagem multidisciplinar e restauração direta em resina composta para a reabilitação de fraturas corono-radiculares. Fraturas de incisivos superiores são uma consequência frequente de traumas em crianças e adolescentes. Pinos de fibra de vidro associados às restaurações em resina composta representam abordagem conservadora para este tipo de situação. Este artigo apresenta caso clinico de um paciente do sexo masculino de 14 anos de idade, com fratura corono- radicular em incisivo lateral superior esquerdo. Inicialmente,o paciente foi submetido à cirurgia periodontal para aumento de coroa clínica. Depois, foi realizada cimentação do pino de fibra de vidro, seguido de restauração direta em resina composta. Por fim, um protetor bucal foi confeccionado para prevenir novo trauma. O tratamento multidisciplinar descrito para reabilitação de fraturas corono-radiculares é simples, proporcionando estética e função com uma abordagem conservadora em pacientes jovens.

Effect of specimen gripping device, geometry and fixation method on microtensile bond strength, failure mode and stress distribution: laboratory and finite element analyses.

OBJECTIVES: Innumerous modifications have been proposed for the microtensile test since its introduction; however, testing parameters are not often well described and wide variations in bond strength are commonly reported. The aim of this study was to evaluate the effect of the test specimen's gripping device, specimen geometry and fixation method on microtensile bond strength, failure mode, and stress distribution when using an etch-and-rinse 2-step adhesive system bonded to human dentin. METHODS: Resin-based composite bonded to occlusal dentin from 21 human molars was used to fabricate dumbbell- and stick-shaped test specimens which were divided into three groups: Di - dumbbell-specimens placed in a Dircks device; GeS - stick-specimens gripped in a Geraldeli's device with Superglue; GeZ - stick-specimens gripped in a Geraldeli's device with Zapit. Specimens were tested to failure in tensile mode and the failure mode was examined under stereomicroscopy and fracture initiation sites were verified by scanning electron microscopy and energy dispersive X-ray spectroscopy. Three-dimensional models of each device/specimen were created and finite element calculations were performed. RESULTS: The effect of the gripping devices on the bond strength was not significant, unless the bond test areas were normalized. The failure mode was influenced by the type of device. Dircks device was less sensitive to human error than Geraldeli's, and produced a more uniform stress distribution at the dumbbell specimen adhesive layer than did the Geraldeli's device at the stick layer. SIGNIFICANCE: Microtensile testing parameters can directly influence the results and consequently inter-study comparisons.