[show abstract][hide abstract] ABSTRACT: The objective of this in vitro study was to compare the degree of microleakage of composite restorations performed by lasers and conventional drills associated with two adhesive systems.
Sixty bovine teeth were divided into 6 groups (n = 10). The preparations were performed in groups 1 and 2 with a high-speed drill (HD), in groups 3 and 5 with Er:YAG laser, and in groups 4 and 6 with Er,Cr:YSGG laser. The specimens were restored with resin composite associated with an etch-and-rinse two-step adhesive system (Single Bond 2 [SB]) (groups 1, 3, 4) and a self-etching adhesive (One-Up Bond F [OB]) (groups 2, 5, 6). After storage, the specimens were polished, thermocycled, immersed in 50% silver nitrate tracer solution, and then sectioned longitudinally. The specimens were placed under a stereomicroscope (25X) and digital images were obtained. These were evaluated by three blinded evaluators who assigned a microleakage score (0 to 3). The original data were submitted to Kruskal-Wallis and Mann-Whitney statistical tests.
The occlusal/enamel margins demonstrated no differences in microleakage for all treatments (p > 0.05). The gingival/dentin margins presented similar microleakage in cavities prepared with Er:YAG, Er,Cr:YSGG, and HD using the etch-and-rinse two-step adhesive system (SB) (p > 0.05); otherwise, both Er:YAG and Er,Cr:YSGG lasers demonstrated lower microleakage scores with OB than SB adhesive (p < 0.05).
The microleakage score at gingival margins is dependent on the interaction of the hard tissue removal tool and the adhesive system used. The self-etching adhesive system had a lower microleakage score at dentin margins for cavities prepared with Er:YAG and Er,Cr:YSGG than the etch-and-rinse two-step adhesive system.
The journal of adhesive dentistry 06/2009; 11(3):221-9. · 0.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: The reattachment of dental fragments is a conservative treatment and should be considered in the restoration of anterior tooth fractures. This study compared the fracture strength of dehydrated and rehydrated tooth fragments submitted to two different bonding techniques.
Sixty human central and lateral mandibular incisors were divided into six groups and sectioned 3 mm from the incisal edge, using a diamond disk. Two reattachment techniques were applied: (a) bonding, using the Single Bond adhesive system and FiltekZ250 composite resin, followed by placement of a chamfer on the fracture line that was filled with composite resin (Groups 1, 3 and 5); and (b) use of the same bonding technique after dentin removal from the tooth fragment (Groups 2, 4 and 6). The following hydration treatments were applied to the fragments before bonding: (a) 48-h hydration (Groups 1 and 2); (b) 48-h dehydration (Groups 3 and 4); (c) 48-h dehydration followed by rehydration 30 min before bonding (Groups 5 and 6). The reattached teeth were mounted in acrylic resin cylinders and stored in distilled water for 24 h. The specimens were fractured at a speed of 1 mm min(-1) in a universal testing machine.
The following mean fracture strengths (kgf) were recorded: (G1) 12.9 +/- 0.6; (G2) 18.8 +/- 4.8; (G3) 7.3 +/- 1.5; (G4) 15.2 +/- 2.4; (G5) 13.4 +/- 2.2; and (G6) 17.1 +/- 3.2. Analyses using two-way anova and the Tukey test (P < 0.01) revealed significant differences between the restorative techniques and the hydration treatments.
The bonding technique that incorporated dentin removal from the fragment before bonding showed greater fracture strength across all groups. Fragment dehydration for 48 h caused a reduction in fracture strength, which was recovered by a 30-min rehydration.
[show abstract][hide abstract] ABSTRACT: The masticatory activity is complex and involves rhythmic mandibular movements under central nervous system control and peripheral sensorial impulses, to aim the food trituration to prepare it to the degluti- tion. The teeth site on the dental arch and its relationship with the antagonist is one of the agents directly involved in this activity performance. Therefore, eventual occlusal disorders could interfere on the mastica - tory system performance. The aim of this work is to review the literature about mastication physiology and the result of the occlusal disorders on the important functional aspect: preferred chewing side. Most of the researchers believe that occlusal disorders alter the masticatory standard function. It would be a functional adaptation through a compensatory mechanism that allows a person with occlusal disorders to accomplish the masticatory function in a satisfactory and comfortable way.
[show abstract][hide abstract] ABSTRACT: Introduction: Posts are important devices to maintain the correct restoration and protect remain dental structure. The aim of this research was to compare the flexural resistance of three types of endodontic posts under a compressive load applied perpendicularly to the axis, at the crown portion. Methods: Thirty canine teeth roots, endodonticaly treated and prepared for post roots, were used. The samples were ran- domly divided in three groups of ten, as follow: group 1, acrylic patterns of endodontic posts were cast in copper-aluminum alloy (DuracastMS); group 2, prefabricated carbon fiber posts were cemented with resin cement and completed with composite core; group 3, prefabricated glass fiber posts were cemented with resin cement and completed with composite core. After 24 hours of storage in saline solution, the samples were tested under load (0,5mm/min) in a Universal Testing Machine until the posts were bent. The maximum load values were registered and calculated according the posts range. Results: The results submitted to ANOVA and Tukey tests (α=0,05) and demonstrated that there was statistically significant difference between the groups. Median (±standard deviation) were: GI - 53,50 (±9,50); GII - 30,99 (±6,61); GIII - 21,96 (±3,67). Conclusions: the cast posts flexural resistance was higher than the prefabrica - ted posts. The prefabricated carbon fiber posts showed better performance than glass fiber ones. DESCRIPTORS: Dental pins - Post and core technique