RESUMEN
AIM: The aim of this study was to assess fracture resistances of simulated immature single-rooted teeth whose roots have been backfilled using 3 different post systems after a 4 mm apical mineral trioxide aggregate (MTA) placement. MATERIALS AND METHODS: Forty-eight maxillary anterior teeth were assigned into four groups. The lengths of each root were standardized by cutting off the coronal and apical portions to obtain 13 ± 1 mm samples and root canals were enlarged. The #6 Peeso reamers were allowed to protrude 1 mm beyond apex to simulate immature teeth. Apical 4 mm of each tooth was filled using MTA. The remaining portions were treated as follows: Group 1 (Control): AH Plus + Gutta-percha cold lateral compaction. Group 2: Glass fiber posts (FRC Postec Plus post) cemented using self-adhesive resin cement. Group 3: Quartz fiber posts (D.T. Light post) cemented using self-adhesive resin cement. Group 4: Zirconia posts (Cosmopost) were placed using self-adhesive resin cement. Specimens were embedded in self-curing acrylic. A compressive load was applied lingually at a crosshead speed of 1 mm/min at an angle of 45º until fracture in a universal testing machine. RESULTS: The mean fracture resistances were 823.17 ± 188.80, 1155.50 ± 190.37, 1208.00 ± 254.32, and 1153.25 ± 195.71 Newtons for Groups 1, 2, 3, and 4, respectively. All experimental groups had significantly higher fracture resistance compared with the control group (P < 0.01). No statistically significant difference was noted between the experimental groups (P > 0.05). CONCLUSIONS: All post systems exerted a similar reinforcing effect to a simulated immature tooth and may be preferred specifically in situations which require additional reinforcement.
Asunto(s)
Técnica de Perno Muñón , Fracturas de los Dientes/prevención & control , Compuestos de Aluminio , Compuestos de Calcio , Combinación de Medicamentos , Humanos , Óxidos , SilicatosRESUMEN
STATEMENT OF PROBLEM: The surface of zirconia ceramic is damaged during grinding, which may affect the mechanical properties of the material. PURPOSE: The purpose of this study was to compare the biaxial flexural strength of zirconia after different grinding procedures and to measure the temperature rise from grinding. MATERIAL AND METHODS: Forty disk-shaped zirconia specimens (15 × 1.2 mm) with a smaller disk in the center of each disk (1 × 3 mm) were divided into 4 groups (n=10). The specimens were ground with a high-speed handpiece and micromotor with 2 different grinding protocols, continual grinding and periodic grinding (10 seconds grinding with 10 seconds duration), until the smaller disk was removed. Control specimens without the center disk (n=10) were analyzed without grinding. The biaxial flexural strengths of the disks were determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture strength (MPa) was recorded, and the results were analyzed using a 1-way ANOVA, Tukey HSD test, Student's t test, and Pearson correlation test (α=05). RESULTS: All grinding procedures significantly decreased flexural strength (P<.01). The mean flexural strength of the high-speed handpiece groups was higher (815 MPa) than that of the micromotor groups (718 MPa). The temperature values obtained from micromotor grinding (127°C) were significantly higher than those from high-speed handpiece grinding (63°C) (P<.01). CONCLUSIONS: Grinding zirconia decreased flexural strength. Zirconia material ground with a high-speed handpiece run continually caused the least reduction in flexural strength.