Effect of preheated bulk-fill composite temperature on intrapulpal temperature increase in vitro.

OBJECTIVES: The aim of study is measurement of in vitro intrapulpal temperature increase when placing room temperature or preheated (54°C and 60°C) bulk-fill composite. MATERIALS AND METHODS: Extracted human lower third molars were selected and class II (MOD) cavities in each tooth were prepared, resulting in a remaining dentin thickness of 1 mm. A K-type thermocouple was placed inside the pulp chamber. Teeth were placed in a 37°C bath, which simulated human body temperature. Teeth were restored with a bulk-fill composite that was stored at room temperature and preheated at 54°C and 60°C. Data were subjected to two-factor mixed-design analysis of variance using a general linear model procedure for repeated measurements. RESULTS: Stage, composite temperature, and stage-composite temperature interaction significantly affected the intrapulpal temperature values (P < .001). CONCLUSIONS: Preheating does not represent significant problems in terms of intrapulpal temperature increase. Even Though the preheating process results in an increase in intrapulpal temperature, this temperature increase is not the critical factor that causes harm to the pulp. CLINICAL SIGNIFICANCE: Preheating can improve material features. Benefits of improved material features are desirable to practitioners. Temperature increase is not the critical factor that harms to the pulp even if the preheating process can result with an increase in intrapulpal temperature.

Usage of fiber-reinforced resin instruments in interproximal surfaces.

OBJECTIVES: The aim of this study was to investigate the effects of fiber-reinforced resin burs on the surface roughness of a nanofilled composite. METHODS: Average surface roughness values (Ra, mum) were measured using a surface profilometer and surface textures after finishing procedures were evaluated using a scanning electron microscope (SEM). Thirty cylindrical specimens were prepared using sectional teflon molds. A nanofilled composite was chosen. After the preparation specimens were divided into three subgroups randomly. After profilometric measurements, representative samples of the mentioned finishing procedures were selected and SEM analyses were carried out. RESULTS: Mylar strip group was statistically different from the other two groups (P<.05). The smoothest surfaces occurred when composite resin samples were light cured against the strips. On the other hand there was no statistical difference between fiber-reinforced resin burs and Sof-Lex discs (P>.05). For fiber-reinforced resin burs scratches and pitting which may be due to plucking of the filler particles during finishing were observed on the surface topography of the composite resin material. On the other hand, for the Sof-Lex discs although scratches were noticed on the surface topography, no pitting was observed. CONCLUSIONS: Fiber-reinforced resin burs can be preferred for the grinding of composite surplus in interproximal surfaces, where the use of Sof-Lex discs can be harmful to soft tissues.

Microleakage of self-etch primer/adhesives in endodontically treated teeth.

BACKGROUND: The authors evaluated the coronal marginal leakage of endodontically treated teeth bonded with four self-etching adhesives and one total-etch adhesive system. MATERIALS AND METHODS: The investigators prepared Class II cavities in 60 extracted human premolars. They performed conventional endodontic therapy using a resin-based sealer and gutta-percha points. They randomly assigned each tooth to a group receiving one of the following adhesives: Adper Prompt L-Pop (3M ESPE, Seefeld, Germany), Clearfil SE Bond (Kuraray, Osaka, Japan), FL Bond (Shofu, Kyoto, Japan), Single Bond (3M ESPE) or Xeno III (Dentsply De Trey, Konstanz, Germany). They restored all teeth with resin-based composite material (Z250, 3M ESPE). Specimens underwent thermocycling and dye penetration and were sectioned longitudinally. The authors photographed the sections under a stereomicroscope. They transferred the images to an IBM-compatible personal computer for quantitative assessment of dye penetration using image analysis software. They analyzed data by means of Kruskal-Wallis and Mann-Whitney U tests (P = .05) and evaluated two specimens from each group under scanning electron microscopy. RESULTS: None of the tested self-etch adhesives completely eliminated microleakage. Dye leakage was restricted to the coronal cavity walls; it did not migrate toward the pulp chamber or toward the root canal. Single Bond and Clearfil SE Bond showed significantly lower dye penetration values at occlusal and gingival margins. CONCLUSIONS: The coronal sealing performance of the tested self-etch adhesive systems in endodontically treated teeth was material-dependent. The use of Clearfil SE Bond in such teeth can help achieve a marginal seal comparable to that achieved with Single Bond.