Evaluation of the position of unerupted mandibular third molars with and without root dilacerations: a study on panoramic radiographs.

BACKGROUND: Factors that can directly influence the extraction of third molars include the position of the tooth and the presence of root dilacerations. Knowledge of these features favors an accurate therapeutic evaluation of third molars; therefore, the aim of this study was to evaluate, using panoramic radiographs, the positioning of unerupted third molars with and without root dilacerations and to verify a possible association between these two variables. METHODS: In this study, 16,136 panoramic radiographs were analyzed, including 1756 lower third molars, in which the positioning was assessed according to the Winter classification and the presence of root dilacerations was determined. The data obtained from the assessments of the frequencies of the positions and the presence of root dilacerations of impacted mandibular third molar was described. A χ2 test was applied to verify a possible association between the variables. RESULTS: The results indicated that the most frequent position was mesioangular (44.5%), followed by horizontal (24.9%), vertical (17.4%), distoangular (12.5%), inverted (0.4%), and linguoangular (0.3%). Of the mandibular third molars evaluated, 35% had root dilacerations. The chi-square test revealed a significant association between the position of the tooth and the presence of root dilacerations (P<0.0001, χ2=34.28). The frequency of root dilaceration was statistically higher for the vertical (45.5%) and distoangular positions (40.9%). CONCLUSIONS: The mesioangular position was the most prevalent location for lower third molars, and the highest frequencies of root dilacerations were observed in the vertical and distoangular positions. Knowledge about the prevalence of root dilacerations and the significant association between the position of the third molars and root dilacerations will allow safer surgical planning for dental extractions of third molars.

Evaluation of the roughness of composite resins submitted to different surface treatments.

The aim of this study was to evaluate the surface roughness of restorative composite resins after polishing with aluminum oxide discs and applying an adhesive layer The following composite resins were used: Filtek Z250 (hybrid, 3MESPE, A2) and Filtek Supreme XT (nanofilled, 3M ESPE, A2E). Thirty specimens of each composite were made using a condensation silicone mold (5.0 x 2.0 mm) into which the composites were inserted and submitted to light pressure. After polymerization using the halogen light source Curing Light 2500 (3M) for 40 seconds, the specimens were assigned to the following groups: G1-Z250/CO- control, did not receive any treatment; G2-Z250/SL--the specimens underwent finishing and polishing with Sof-Lex discs; G3-Z250/ADE, application of an adhesive layer on the top of the specimen and light curing for 20 seconds. Groups G4, G5 and G6 followed the same treatment sequence, but using Filtek Supreme XT The specimens were stored in deionized water at 37 degrees C for 24 h. Three readings of surface roughness were made for each specimen. The results were submitted to variance analysis by Two-Way ANOVA Test and Tukey HSD Test. The mean values obtained were: G3 (0.2325 +/- 0.1484 microm) and G6 (0.2266 +/- 0.0463 microm), which were higher than the other groups and did not differ statistically from each other. Groups G1 (0.1023 +/- 0.0464 microm), G4 (0.1083 +/- 0.0241 microm), G5 (0.1160 +/- 0.0252 microm) and G2 (0.1360 +/- 0.0131 microm) had the lowest average roughness and did not differ statistically among each other. It was concluded that the Sof-Lex discs performed better for the surface treatment of the composites resins tested, producing similar values of surface roughness for both composites. Covering with dentin adhesive increased the surface roughness in both composites.

Evaluation of the roughness of composite resins submitted to different surface treatments / Evaluación de la rugosidad de resinas compuestas después de diferentes tratamientos de superficie

El propósito del presente estudio fue evaluar la rugosidad superficial de resinas compuestas después de ser pulidas con discos de óxido de aluminio y de aplicar una capa de adhesivo. Se utilizó resina Filtek Z250 y Filtek Supreme XT. Se fabricaron treinta especímenes de cada resina utilizando una matriz de silicona (5,0 x 2,0 mm). Después de su polimerización por 40 segundos, se formaron los siguientes grupos: G1-Z250/CO – control, que no recibió ningún tratamiento; G2-Z250/SL – los especímenes fueronacabados y pulidos con discos Sof-Lex; G3-Z250/ADE – se aplicó una capa de adhesivo en la parte superficial de los especímenes polimerizada por 20 segundos. Los grupos G4, G5 y G6 siguieron el mismo patrón, utilizando resina Filtek Supreme XT. Tres lecturasde rugosidad superficial fueron hechas en cada especímen. Se evaluaron mediante la pruebas de ANOVA Two-Way y Tukey HDS (p = 0,05), obteniendo los siguientes valores: G3 (0.2325 ± 0.1484 μm) y G6 (0.2266 ± 0.0463 μm) obtuvieron valores superiores a los otros grupos sin diferencia estadística. G1 (0.1023 ± 0.0464 μm), G4 (0.1083 ± 0.0241 μm), G5 (0.1160 ± 0.0252 μm) y G2(0.1360 ± 0.0131 μm) obtuvieron los menores valores de rugosidadsuperficial sin diferencia estadística. Se concluyó que los discos Sof-Lex presentaron un mejor desempeño para el tratamiento superficial de las resinas compuestas, siendo capaces de producirvalores similares de rugosidad de la superficie de ambos compuestos.La aplicación de una capa hidrofóbica de monómeros en las resinas produjo una elevada rugosidad superficial.

Evaluation of the roughness of composite resins submitted to different surface treatments / Evaluación de la rugosidad de resinas compuestas después de diferentes tratamientos de superficie

El propósito del presente estudio fue evaluar la rugosidad superficial de resinas compuestas después de ser pulidas con discos de óxido de aluminio y de aplicar una capa de adhesivo. Se utilizó resina Filtek Z250 y Filtek Supreme XT. Se fabricaron treinta especímenes de cada resina utilizando una matriz de silicona (5,0 x 2,0 mm). Después de su polimerización por 40 segundos, se formaron los siguientes grupos: G1-Z250/CO û control, que no recibió ningún tratamiento; G2-Z250/SL û los especímenes fueronacabados y pulidos con discos Sof-Lex; G3-Z250/ADE û se aplicó una capa de adhesivo en la parte superficial de los especímenes polimerizada por 20 segundos. Los grupos G4, G5 y G6 siguieron el mismo patrón, utilizando resina Filtek Supreme XT. Tres lecturasde rugosidad superficial fueron hechas en cada especímen. Se evaluaron mediante la pruebas de ANOVA Two-Way y Tukey HDS (p = 0,05), obteniendo los siguientes valores: G3 (0.2325 ± 0.1484 μm) y G6 (0.2266 ± 0.0463 μm) obtuvieron valores superiores a los otros grupos sin diferencia estadística. G1 (0.1023 ± 0.0464 μm), G4 (0.1083 ± 0.0241 μm), G5 (0.1160 ± 0.0252 μm) y G2(0.1360 ± 0.0131 μm) obtuvieron los menores valores de rugosidadsuperficial sin diferencia estadística. Se concluyó que los discos Sof-Lex presentaron un mejor desempeño para el tratamiento superficial de las resinas compuestas, siendo capaces de producirvalores similares de rugosidad de la superficie de ambos compuestos.La aplicación de una capa hidrofóbica de monómeros en las resinas produjo una elevada rugosidad superficial.(AU)

Effect of water storage and surface treatments on the tensile bond strength of IPS Empress 2 ceramic.

PURPOSE: The aim of this study was to evaluate the effect of water storage (24 hours and 1 year) on the tensile bond strength between the IPS Empress 2 ceramic and Variolink II resin cement under different superficial treatments. MATERIALS AND METHODS: One hundred and eighty disks with diameters of 5.3 mm at the top and 7.0 mm at the bottom, and a thickness of 2.5 mm were made, embedded in resin, and randomly divided into six groups: Groups 1 and 4 = 10% hydrofluoric acid for 20 seconds; Groups 2 and 5 = sandblasting for 5 seconds with 50 microm aluminum oxide; and Groups 3 and 6 = sandblasting for 5 seconds with 100 microm aluminum oxide. Silane was applied on the treated ceramic surfaces, and the disks were bonded into pairs with adhesive resin cement. The samples of Groups 1 to 3 were stored in distilled water at 37 degrees C for 24 hours, and Groups 4 to 6 were stored for 1 year. The samples were subjected to a tensile strength test in an Instron universal testing machine at a crosshead speed of 1.0 mm/min, until failure. The data were submitted to analysis of variance and Tukey's test (5%). RESULTS: The means of the tensile bond strength of Groups 1, 2, and 3 (15.54 +/- 4.53, 10.60 +/- 3.32, and 7.87 +/- 2.26 MPa) for 24-hour storage time were significantly higher than those observed for the 1-year storage (Groups 4, 5, and 6: 10.10 +/- 3.17, 6.34 +/- 1.06, and 2.60 +/- 0.41 MPa). The surface treatments with 10% hydrofluoric acid (15.54 +/- 4.53 and 10.10 +/- 3.17 MPa) showed statistically higher tensile bond strengths compared with sandblasting with 50 microm(10.60 +/- 3.32 and 6.34 +/- 1.06 MPa) and 100 microm (7.87 +/- 2.26 and 2.60 +/- 0.41 MPa) aluminum oxide for the storage time 24 hours and 1 year. CONCLUSIONS: Storage time significantly decreased the tensile bond strength for both ceramic surface treatments. The application of 10% hydrofluoric acid resulted in stronger tensile bond strength values than those achieved with aluminum oxide.