Evaluation of root external temperature during the application of ultrasound in removal of intraradicular posts.

This study evaluated the temperature rise on external root surfaces by simulating the removal of metallic posts by applying ultrasound, with or without refrigeration and at different times. The crowns of 30 healthy maxillary central incisors were removed and the roots were treated endodontically. The prosthetic spaces were prepared and impressions were taken with self-curing acrylic resin. After casting with a copper-aluminum alloy, the posts were blasted with aluminum oxide and cemented with resin cement. The specimens were randomly assigned to three groups according to the time of ultrasonic vibration (30, 60, or 120 seconds) and were subdivided into two groups, those cooled with and without water refrigeration. A thermocouple connected to a digital thermometer was positioned on the root external surface and the maximum temperature was recorded. Data were submitted to ANOVA and Tukey's test. Analysis of the results revealed statistical difference among groups (p < 0.01). Ultrasound (with and without water spray) increased root temperature significantly, reaching values of more than 50 degrees C. The exception was the group that used 30 seconds of ultrasound with refrigeration; root temperature reached 35.4 degrees C, making it the only tested condition that remained below the critical value (50 degrees C).

Retention of radicular posts varying the application technique of the adhesive system and luting agent

This study evaluated in vitro the retention of intracanal cast posts cemented with dual-cure resin varying the application method of the primer/adhesive solution and luting agent in the prosthetic space prepared to receive the posts. Sixty endodontically treated maxillary canines had their crowns discarded, and their roots were embedded in acrylic resin. The prosthetic spaces were prepared with Largo burs mounted on a low-speed handpiece coupled to a parallelometer in order to maintain length and diameter of intraradicular posts constant and to guarantee that the preparations were parallel after casting. Two groups (n = 30) were randomly formed according to the device used to apply the adhesive system: microbrush or standard bristle brush (control). Each group was divided into 3 subgroups (n = 10) according to the technique used to place the luting agent into the root canal: using only a lentulo spiral before setting the post, applying it onto the post surface, or combining both methods. After 72 hours, the tensile force required to dislodge each post was determined by a universal testing machine (Instron 4444) set at a speed of 1 mm/min. The results indicated that the use of the microbrush yielded higher bond strength values (0.1740 ± 0.04 kN) than those recorded for the bristle brush tip (0.1369 ± 0.04 kN, p < 0.001). Bonferroni's test demonstrated a higher retention (p < 0.001) in radicular post cemented with the technique that combined both methods (lentulo + post: 0.1787 ± 0.03 kN) than that obtained with lentulo (0.1461 ± 0.065 kN) or post (0.1416 ± 0.03 kN) alone. The interactions between the adhesive system and luting agent application techniques presented statistical difference (p < 0.001). It was concluded that the best performance in terms of tensile strength among the tested conditions was obtained when the adhesive system was applied with a microbrush and the luting agent was taken into the root canal with lentulo...

O objetivo deste trabalho foi avaliar in vitro a retenção de pinos intra-radiculares variando-se a técnica de aplicação do agente adesivo e do cimento resinoso dual no espaço protético preparado para a recepção do pino. Sessenta caninos superiores tratados endodonticamente tiveram as coroas descartadas e as raízes incluídas em resina acrílica. Os espaços protéticos foram preparados com broca de Largo acionada por micromotor acoplado a um paralelômetro, a fim de manter constantes o comprimento e diâmetro dos pinos intra-radiculares e o paralelismo dos preparos após a fundição. Os pinos foram divididos aleatoriamente em 2 grupos (n = 30) conforme a técnica de aplicação do agente adesivo: com "microbrush" ou com pincel (controle). Cada grupo foi subdividido em três subgrupos (n = 10) segundo a técnica de aplicação do agente cimentante: com o próprio pino, com broca de lentulo previamente ao posicionamento do pino ou associação dos dois modos. Após 72 horas do processo de cimentação, os pinos foram tracionados pela Máquina Universal de Ensaios (Instron 4444) à velocidade de 1 mm/min. Os resultados mostraram diferença estatística significante (p < 0,001) entre as técnicas de aplicação do agente adesivo com "microbrush" (0,1740 ± 0,04 kN) e pincel (0,1369 ± 0,04 kN). Em relação à técnica de aplicação do cimento no interior do espaço protético, a da associação entre lentulo e pino (0,1787 ± 0,03 kN) foi estatisticamente diferente (p < 0,001) das do lentulo (0,1461 ± 0,065 kN) e do pino (0,1416 ± 0,03 kN) isoladamente. As interações entre as técnicas de aplicação do agente adesivo e do agente cimentante apresentaram diferença estatística (p < 0,001). Concluiu-se que as interações entre as técnicas de aplicação do agente adesivo com "microbrush" e aplicação do agente cimentante com lentulo (0,1961 ± 0,04 kN) e com lentulo e pino associados (0,1911 ± 0,02 kN) propiciaram os maiores valores da força de tração.

Retention of radicular posts varying the application technique of the adhesive system and luting agent.

This study evaluated in vitro the retention of intracanal cast posts cemented with dual-cure resin varying the application method of the primer/adhesive solution and luting agent in the prosthetic space prepared to receive the posts. Sixty endodontically treated maxillary canines had their crowns discarded, and their roots were embedded in acrylic resin. The prosthetic spaces were prepared with Largo burs mounted on a low-speed handpiece coupled to a parallelometer in order to maintain length and diameter of intraradicular posts constant and to guarantee that the preparations were parallel after casting. Two groups (n = 30) were randomly formed according to the device used to apply the adhesive system: microbrush or standard bristle brush (control). Each group was divided into 3 subgroups (n = 10) according to the technique used to place the luting agent into the root canal: using only a lentulo spiral before setting the post, applying it onto the post surface, or combining both methods. After 72 hours, the tensile force required to dislodge each post was determined by a universal testing machine (Instron 4444) set at a speed of 1 mm/min. The results indicated that the use of the microbrush yielded higher bond strength values (0.1740 +/- 0.04 kN) than those recorded for the bristle brush tip (0.1369 +/- 0.04 kN, p < 0.001). Bonferroni's test demonstrated a higher retention (p < 0.001) in radicular post cemented with the technique that combined both methods (lentulo + post: 0.1787 +/- 0.03 kN) than that obtained with lentulo (0.1461 +/- 0.065 kN) or post (0.1416 +/- 0.03 kN) alone. The interactions between the adhesive system and luting agent application techniques presented statistical difference (p < 0.001). It was concluded that the best performance in terms of tensile strength among the tested conditions was obtained when the adhesive system was applied with a microbrush and the luting agent was taken into the root canal with lentulo spirals alone (0.1961 +/- 0.04 kN) and combining both methods (lentulo + post: 0.1911 +/- 0.02 kN).

Efficacy of ultrasound in removal of intraradicular posts using different techniques.

The efficacy of ultrasound in removing cast metal posts was evaluated in this in vitro study using one or two ultrasound units and ultrasonic vibration for various lengths of time. The crowns of 30 healthy maxillary canines were removed, the roots were embedded in acrylic resin blocks, and the root canals were treated endodontically. The canals were prepared and their impressions were taken with self-curing acrylic resin. After casting with copper-aluminum alloy, the posts were blasted with aluminum oxide and cemented with Panavia F resin cement. The specimens were divided into five groups. In groups I and II, only one ultrasound unit was used for 30 and 60 s, respectively; in groups III and IV, two ultrasound units were used simultaneously for 30 and 60 s, respectively; in group V, ultrasound was not used (control). Ultrasonic vibrations were applied with an Enac OE-5 ultrasound unit and an ST-09 tip. All samples were subjected to traction on an Instron machine (model 4444) at a cross-head speed of 1 mm/min. Analysis of the results revealed a statistically significant difference between the groups (ANOVA, P < 0.01); however the difference between groups II and IV was not statistically significant. The efficacy of ultrasound in removing intraradicular posts was confirmed, and the most effective technique was the use of two ultrasound units, independent of the length of time ultrasound was applied.

Prevalência de projeção cervical de esmalte em molares inferiores: avaliação da possibilidade de diagnóstico utilizando RX convencional e digital e tomografia / Prevalence of enamel cervical projections in mandibular molars: evaluation of possible diagnosis with conventional and digital RX and tomograph

Para a realização de um correto diagnóstico e adequado tratamento da bifurcação radicular de molares inferiores envolvidos pela doença periodontal inflamatória, é necessário o conhecimento pleno da anatomia cervical dos dentes. Uma das complexidades anatômicas encontradas é a projeção cervical de esmalte (PCE). Avaliou-se a presença da PCE em 462 molares inferiores, e a possibilidade de diagnóstico destas projeções por meio de radiografia convencional, digital e tomográfica. As PCE foram classificadas em Grau 0 (ausência de projeção), Grau I (pequena), Grau II (próxima da furca, sem atigi-la) e Grau III (atingindo a furca). No primeiro molar foi observado, nas faces vestibular e lingual, respectivamente,que 45,3 por cento e 70,9 por cento apresentaram Grau 0, 42,6 por cento e 26,4 por cento Grau I, 5,4 por cento e 2,7 por cento Grau II e 6,7 por cento e 0 por cento Grau III. No segundo molar foi observado, nas faces vestibular e lingual, respectivamente, que 44,5 por cento e 84,9 por cento apresentaram Grau 0, 35,6 por cento e 14,3 por cento Grau I, 12,3 por cento e 0,68 por cento Grau II e 7,5 por cento e 0 por cento Grau III. No terceiro molar foi observado, nas faces vestibular e lingual, respectivamente, que 61,9 por cento e 92,2 por cento apresentaram Grau 0, 20,8 por cento e 5,9 por cento Grau I, 8,3 por cento e 1,7 por cento Grau II 8,9 por cento e 0 por cento Grau III . Nenhum dente apresentou PCE nas faces proximais. Concluiu-se que houve maior prevalência de PCE na face vestibular e que a de Grau I foi a mais encontrada nos dentes estudados. Nenhum dos métodos de diagnóstico utilizados foi capaz de evidenciar a projeção cervical de esmalte

Influence of ultrasound, with and without water spray cooling, on removal of posts cemented with resin or zinc phosphate cements.

The efficacy of ultrasound, with and without water spray, was evaluated in vitro on the amount of force necessary to dislodge posts cemented with resin or zinc phosphate. Forty-two samples were divided into six groups: groups 1, 2, and 3, posts cemented with zinc phosphate; groups 4, 5, and 6, posts cemented with resin (Panavia F); groups 1 and 4 (controls), no ultrasound; groups 2 and 5, ultrasound without water spray; and groups 3 and 6, ultrasound with water spray. The Instron testing machine was used. Ultrasound without water spray significantly reduced (71%) the force necessary to displace posts cemented with Panavia F (p < 0.01); however, this value was similar to the efficacy of ultrasound with water spray for posts cemented with zinc phosphate (reduction of 75%). We conclude that cooling with ultrasound interferes with the force necessary for post removal, depending on the type of cement used.