Effect of Magnification during Post Space Preparation on Root Cleanness and Fiber Post Bond Strength.

The aim of this study was to evaluate the effect of magnification during post space preparation on root cleanness and on fiber post bond strength. Methods: Thirty human central upper incisors with similar root canal in size and shape were selected, decoronated to 15 mm and endodontically filled. The teeth were assigned into 3 groups (n=10), according to the method of magnification during post space preparation inspection: Control, using naked eye; loupe, using a dental surgical 3x magnifying glass; surgical microscope, using a 6x surgical microscope. The roots were scanned by using micro-CT before and after post space preparation for residue remnants evaluation. Fiber posts were cemented using self-adhesive resin cement (Rely X U200, 3M-ESPE). Two 1-mm-thick slices from the cervical, medium and apical thirds were submitted to a push-out test (PBS). Failures modes were classified. PBS data were analyzed by using two-way ANOVA with repeated measurement and the Tukey test. The significance level was set at 5%. The method of visualization had no effect on PBS (p=0.556). The cervical region had higher values than apical region irrespective of the inspection method (p=0.012). Adhesive failure between the resin cement and dentin was the prevalent failure mode for all groups. Micro-CT analysis showed no difference on root cleanness into the root canal after post space preparation. The use of magnification devices as loupe and microscope while performing post space do not improve the PBS and did not affect sealer remain of decoronated anterior teeth.

Effect of Resin Cement Porosity on Retention of Glass-Fiber Posts to Root Dentin: An Experimental and Finite Element Analysis

The aim of this study was to evaluate the effect of porosity of self-adhesive resin on the stress distribution, post retention and failure mode of fiber post cemented to human root dentin. Ten human central upper incisors with circular root canal were selected. They were sectioned with 15 mm and were endodontically filled. The roots were scanned using micro-CT after post space preparation for root filling remaining evaluation. Fiber posts were cemented using self-adhesive resin cement (Rely X U200, 3M-ESPE). Two 1-mm-thick slices from the cervical, medium and apical thirds were scanned for resin cement bubbles volume measurements and submitted to a push-out test (PBS). Three operators using stereomicroscopy and confocal laser microscopy classified the failure mode. Stress distributions during the push-out test were analyzed using 3D finite element analysis. PBS values (MPa) were submitted to one-way ANOVA and Tukey's post hoc tests and the failure modes using the Kappa coefficient to assess inter-operator agreement. Chi-square test was used to determine significant differences between the methods ( = 0.05). Push-out bond strength was significantly affected by the bubbles presence in all root depth (p<0.05). The stress concentration was higher when the bubbles were present. Adhesive dentin/resin cement interface failure was the most frequent type of failure. Confocal microscopy was better than stereomicroscopy for failure analysis. Bubbles generated during resin cement insertion into the root canal negatively affect the stress distribution and the bond strength. The use of confocal microscopy is recommended for failure analysis.

Resumo O objetivo deste estudo foi avaliar o efeito da integridade do cimento resinoso autoadesivo, expresso pela presença de bolhas, sobre a distribuição de tensão, resistência adesiva e modo de falha de pinos de fibra cimentados à dentina radicular humana. Dez incisivos centrais superiores humanos com canais radiculares circulares foram selecionados. Os mesmos foram seccionados com 15 mm e tratados endodonticamente. As raízes foram digitalizadas utilizando micro-CT após preparo do pino para avaliação de remanescentes de material obturador. Pinos de fibra foram cimentados utilizando cimento autoadesivo (Rely X U200, 3M-ESPE). Duas fatias de 1 mm de espessura dos terços cervical, médio e apical foram escaneados para mensuração do volume de bolhas no cimento resinoso e submetidos ao teste de push-out. Três operadores classificaram o modo de falha utilizando microscopia confocal à laser e lupa estereoscópica. Distribuição de tensão foi analisada pelo método de elementos finitos 3D. Os valores de resistência adesiva (MPa) foram submetidos ao teste ANOVA em fator único seguido do teste de Tukey. Foi utilizado o coeficiente de Kappa para avaliar a concordância entre operadores. O teste Qui-quadrado foi utilizado para determinar diferenças significativas entre os métodos (α=0,05). A resistência adesiva foi significativamente afetada pela presença de bolhas independentemente da profundidade radicular (p<0,05). A concentração de tensão foi maior na presença de bolhas. Maior frequência de falha adesiva ocorreu na interface cimento/dentina. A microscopia confocal foi melhor do que estereomicroscopia para análise de falhas. A presença de bolhas afetou negativamente a distribuição de tensão e a resistência de união. Recomenda-se uso de microscopia confocal para análise de falhas.

Influence of different load application devices on fracture resistance of restored premolars

This in vitro study analyzed the effect of different load application devices on fracture resistance and failure mode of maxillary premolars restored with composite resin. Sixty human maxillary premolars received standardized mesio-occluso-distal cavity preparations and were restored with composite resin. The specimens were randomly divided into 6 groups (n=10). Compressive loading was applied using 6 different metallic devices: S2: 2-mm sphere; S6: 6-mm sphere; C2: 2-mm cylinder; C6: 6-mm cylinder; WS: wedge shape device; and MAT: individualized metallic antagonist tooth. Data were analyzed statistically using one-way ANOVA and Tukey's test (α=0.05). The failure mode was recorded based on the 4 sequential levels. Statistical analysis revealed that WS presented significantly higher fracture resistance than S6 and C6. No significant difference was found among MAT, C2, S2 and S6. Sphere and cylinder with 6 mm were similar, with the lowest values of all groups. MAT presented the least number of catastrophic failures while C2, S2 and WS presented the highest. The type of load application device influences significantly the behavior of the teeth-restoration complex during mechanical fracture resistance test.

Este estudo avaliou o efeito de diferentes tipos de dispositivos de aplicação de carga na resistência à fratura de pré-molares superiores restaurados com resina composta. Sessenta pré-molares humanos receberam preparo mésio-ocluso-distal padronizado e as cavidades foram restauradas com resina composta. As amostras foram aleatoriamente divididas em 6 grupos (n=10). Carregamento de compressão foi realizado usando seis diferentes dispositivos metálicos de aplicação de carga: S2 e S6: esfera de 2 mm e 6 mm de diâmetro respectivamente; C2 e C6: cilindro de 2 mm e 6 mm de diâmetro respectivamente; WS: lâmina de faca e MAT: antagonista individualizado em metal. Os resultados foram submetidos à análise de variância e teste de Tukey (p<0,05). O modo de falha foi classificado em 4 níveis e estão apresentado em porcentagem. O dispositivo WS resultou em maior resistência a fratura de pré-molares que S6 e C6. Não houve diferença estatística entre os grupos MAT, C2, S2 e S6. Menor resistência foi verificada com o uso de S6 e C6. O dispositivo MAT resultou em menor número de falhas catastróficas enquanto nos grupos C2, S2 e WS essas falhas foram significativas. O tipo de dispositivo de aplicação de carga influenciou significativamente no comportamento do complexo dente-restauração durante o teste de resistência à fratura.

Influence of different load application devices on fracture resistance of restored premolars.

This in vitro study analyzed the effect of different load application devices on fracture resistance and failure mode of maxillary premolars restored with composite resin. Sixty human maxillary premolars received standardized mesio-occluso-distal cavity preparations and were restored with composite resin. The specimens were randomly divided into 6 groups (n=10). Compressive loading was applied using 6 different metallic devices: S2: 2-mm sphere; S6: 6-mm sphere; C2: 2-mm cylinder; C6: 6-mm cylinder; WS: wedge shape device; and MAT: individualized metallic antagonist tooth. Data were analyzed statistically using one-way ANOVA and Tukey's test (α=0.05). The failure mode was recorded based on the 4 sequential levels. Statistical analysis revealed that WS presented significantly higher fracture resistance than S6 and C6. No significant difference was found among MAT, C2, S2 and S6. Sphere and cylinder with 6 mm were similar, with the lowest values of all groups. MAT presented the least number of catastrophic failures while C2, S2 and WS presented the highest. The type of load application device influences significantly the behavior of the teeth-restoration complex during mechanical fracture resistance test.

Avaliação clínica de clareamento caseiro com gel de peróxido de carbamida industrializado e manipulado em farmácia / Tooth bleaching clinical evaluation with industrialized and drugstore manipulated carbamide peroxide gel

Este trabalho objetivou avaliar clinicamente o uso de clareamento dental caseiro com peróxido de carbamida 10% industrializado e manipulado. Quarenta pacientes foram selecionados com indicação de receber clareamento caseiro e divididos em dois grupos: G1- peróxido de carbamida 10% com Carbopol manipulado em drogaria e G2- peróxido de carbamida 10% com Carbopol industrializado (Whiteness-FGM-Joinvile-SC-Brasil). A análise se baseou nos parâmetros: variação do grau de escurecimento dental por meio de escala de cores (Vita Classic); satisfação pessoal do paciente; sensibilidade pós-operatória, irritação gengival e vitalidade pulpar. Os dados obtidos foram analisados qualitativamente mediante distribuição por freqüência. Os resultados foram: alteração de cor após uma semana de uso do gel clareador: G1- redução de um nível de saturação e G2- redução de dois níveis de saturação e após duas semanas de uso do gel clareador; satisfação do paciente: G1- 68,0% e G2- 82,7%; sensibilidade pós-operatória: G1- 40,0% e G2- 10,0%; irritação gengival: G1-10,0% e G2- 5,0%. Não houve alteração na vitalidade pulpar com o uso dos dois produtos analisados. Pôde-se concluir que os dois materiais apresentaram desempenhos diferenciados, sendo o produto industrializado o mais eficiente para o uso clínico.

The aim of this study was to realize the clinical follow-up of vital tooth bleaching realized with manipulated and industrialized 10% carbamide peroxide gel. Forty patients were selected with indication to receive tooth bleaching and divided in two groups: G1-Twenty patients received drugstore manipulated 10% carbamide peroxide with carbopol, and G2- twenty patients received industrialized 10% carbamide peroxide (Whiteness-FGM-Joinvile-SC-Brasil). The analysis if based on the parameters: degree of tooth discoloration before and after treatment, using Vita shade guide; personal satisfaction of patients; post-operative tooth sensibility; gingival irritation and pulp vitality. The data were analyzed qualitatively by frequency distribution. The results showed: color alteration after one week of use of the gel: G1- reduction of a level of saturation and G2- reduction of two levels of saturation; e after two weeks of use of the gel: satisfaction of the patient: G1- 68.0% and G2- 82,7%; post-operative tooth sensibility: G1- 40.0% and G2- 10,0%; gingival irritation: G1-10,0% and G2- 5,0%. It did not have alteration in the pulp vitality with the use of the two analyzed products. It can conclude that the manipulated and industrialized 10% carbamide peroxide showed different results, been industrialized gel more efficient to clinical usage.