ObjectivesThe purpose of this study was to compare the flexural strength and modulus of two commercial resin composites, at room temperature and 40, 45 and 50°C prior to light polymerization with standard and step-cure protocols.MethodsOne nanohybrid (Grandio, VOCO, Cuxhaven, Germany), and microhybrid composite resin (Filtek Z250, 3M ESPE, St. Paul, MN, USA) were used. The materials were inserted into rectangular moulds at room temperature or preheated to a temperature of 40, 45 or 50°C and cured with standard or step-cure protocols with high intensity halogen (Elipar Highlight, 3M-ESPE, St. Paul, MN, USA). Ten specimens were prepared for each preheating and light curing protocol. A three-point bending test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed by one-way analysis of variance and Tukey’s post hoc tests (P<.05) to examine the effect of curing protocol and preheating. Pearson’s correlation test was used to determine the correlation between tested mechanical properties and preheating.ResultsThere were no statistically significant difference between tested mechanical properties of the materials, curing protocols and temperature of the materials. No significant correlation was found between preheating and tested mechanical properties.ConclusionsThe mechanical properties of the tested materials did not changed by preheating so the tested materials could be preheated because of the other potential clinical advantages like more adaptation to the cavity walls.

The aim of this in vitro study was to evaluate the effect of cervical hypersensitivity treatments (neodymium yttrium aluminum garnet [Nd:YAG] laser and conventional techniques) on the microtensile bond strengths of adhesives to treated dentin. The buccal cervical enamel of 42 freshly extracted human mandibular third molars was ground flat to expose the cervical dentin. The dentin surfaces were polished with a series of silicon carbide papers, and the smear was removed with an ethylenediamine tetra-acetic acid solution. The teeth were randomly divided into six groups as follows: group 1, Vivasens; group 2, BisBlock; group 3, fluoride gel; group 4, Nd:YAG laser; group 5, Clearfil SE + Nd:YAG laser; and group 6, no treatment (control). The specimens were then restored with a two-step self-etch adhesive, with the exception of group 5. Five specimens from each group were restored with a nanohybrid composite resin. The adhesive interface of two specimens from each group was examined using scanning electron microscopy. The specimens were sectioned perpendicularly to the adhesive interface to produce beams (adhesive area 1 mm(2)). The beams were then attached to a microtensile tester and stressed to failure at 1 mm/min. The data were compared using one-way analysis of variance at a significance level of 0.05. The microtensile bond strengths of the control group were significantly higher than those found for group 1, group 2, group 3, and group 4 (p< 0.05). No significant difference was found between group 5 and the control group. Most of the premature failures were seen in group 2 (80%), and the fewest premature failures were seen in group 5 (13.3%). The SEM findings verified the microtensile test findings. In conclusion, desensitizing treatment procedures (with the exception of Clearfil SE + Nd:YAG laser) reduced the microtensile bond strength of a two-step self-etch adhesive to dentin.

The use of an intraoral camera aided in the treatment of occlusal surfaces of molars. SUMMARYThis study assessed the restorative treatment options of the occlusal surfaces of teeth examined with unaided visual assistance, an intraoral camera and an operating microscope. Sixty-eight extracted human molars were mounted to perform mouth models with a premolar in contact on both sides. Four observers examined the models in a phantom head, which simulated clinical conditions, using three techniques: unaided visual examination, intraoral camera and operating microscope. The observers were asked to assess the occlusal surface of each tooth and make a treatment decision based on the following scale: 1) the occlusal surface being sound and "not needing a restoration," 2) the occlusal surface having a subsurface or enamel lesion. No operative treatment was needed at this visit, but special attention was given to this surface at recall visits: "preventive care-defer treatment" and 3) the surface had a carious lesion and "needed a restoration." The teeth were then sectioned in the mesio-distal direction and examined under a stereomicroscope with 10x magnification to determine the true extent of caries. Statistical analysis was conducted by calculating percentages and kappa values of the restorative treatment scores based on examinations by four observers. According to all the observers' treatment decisions, the kappa values were found to be 0.341 (p<0.001), 0.471 (p<0.001) and 0.345 (p<0.001) for unaided visual examination, intra- As a result of a comparison between the unaided visual examination and operating microscope, the use of an intraoral camera improved the restorative treatment decisions of the occlusal surfaces on posterior teeth.

The aim of this in vitro study was to evaluate the effect of different disinfection methods on the initial microtensile bond strength of a two-step, self-etch adhesive to dentin. Twenty mandibular molars were sectioned parallel to the occlusal plane to expose the mid-coronal dentin. All of the teeth were divided into four groups (n = 5 per group): (1) in group OZ, the dentin surfaces were exposed to ozone gas from the Ozonytron X delivery system (OzonyTron X-Bioozonix, Munich, Germany), (2) in group ND, the dentin surfaces were irradiated with an Nd:YAG laser (Pulsmaster 600 IQ, American Dental Technologies, U.S.), (3) in group CHX, the dentin surfaces were treated with a 2% chlorhexidine solution, and (4) in the control group, no treatment was applied. In all of the groups, the teeth were restored with Clearfil SE Bond (Kuraray, Tokyo, Japan) and Clearfil Majesty Posterior (Kuraray, Tokyo, Japan), according to the manufacturer's instructions. The teeth were sectioned perpendicular to the bonded surface (surface area of approximately 1 mm(2)). Thus, six to seven specimens were obtained from each tooth, and a total of 34 specimens were analyzed in each group. The specimens were attached to the microtensile test machine (Micro Tensile Tester, T-61010 K, Bisco, U.S.). The data was analyzed using the one-way analysis of variance (ANOVA) and Tukey test (p < 0.05). Fracture modes of each specimen were determined using a stereomicroscope (SZ-PT Olympus, Tokyo, Japan) and a scanning electron microscope (SEM). The lowest bond strength occurred in the OZ group. Significant differences were determined only between group OZ and the other groups (group ND, group CHX, and control group) (p < 0.05). In conclusion, although ozone decreased the microtensile bond strength of the self-etch adhesive system to dentin, the Nd:YAG laser and 2% chlorhexidine did not change the microtensile bond strength so in context of the present study it would appear that the Nd:YAG laser and 2% chlorhexidine may be used as pre-restorative sterilization procedures on the dentin prior to the application of a two-step, self-etch adhesive.

This in vitro study investigated the effect of use of three dentine bonding agents: Scotchbond Multi-Purpose Plus (3M Dental Products, St. Paul, Minnesota, U.S.A.), Syntac (Vivadent, Schaan, Liechtenstein), Optibond Dual Cure (Kerr, Romulus, MI, U.S.A.) on microleakage and shear bond strength of a fissure sealant (Helioseal F, Vivadent, Schaan, Liechtenstein) bonded to either dry or wet (saliva contaminated) enamels of primary teeth. Newly extracted 112 non-carious primary teeth were sectioned and embedded in resin blocks. Eight groups were formed for each test. Each group consisted of 14 specimens. Group 1 and 2: fissure sealant was applied directly to etched enamel in dry and wet condition, respectively; Group 3 and 4: fissure sealant was applied onto etched and Scotch-bond Multi-Purpose Plus treated enamel in dry and wet condition, respectively; Group 5 and 6: fissure sealant was applied onto etched and Syntac treated enamel in dry and wet condition, respectively; Group 7 and 8: fissure sealant was applied onto etched and Optibond Dual Cure treated enamel in dry and wet condition, respectively. The results revealed that the use of an enamel-dentine bonding agent under fissure sealant increased the bond strength and decreased the microleakage. The use of enamel-dentine bonding agents under sealant in moisture contaminated conditions gave better results than applying sealant alone onto non-contaminated teeth. Finally, Scotchbond Multi-Purpose Plus yielded the best results for both tests.