Evaluation of the influence of light-curing units on the degree of conversion in depth of a bulk-fill resin

It is known that bulk-fill have been widely studied and used by dentists in the clinic. However, the use of light-curing units that do not have the ability to adequately light-cure these materials at the appropriate depth can affect their clinical perfor

Chx stabilizes the resin/demineralized dentin interface

The aim of this study was to evaluate the effect of 2% chlorhexidine diglueonate (CHX) on microtensile bond strength (μTBS) between an adhesive system and under 3 dentin conditions. For that, this study evaluated the adhesive interface at initial, after 6 months and 1 year of storage. Forty-eight human third molars were prepared and randomly divided into 3 groups, according to dentin substrates: Sound dentin (Sd), caries-infected dentin (Ci) and caries-affected dentin (Ca). The groups were subdivided into two according to the dentin pre-treatment: Application of 2% CHX or without pre-treatment (control). The dentin surfaces were etched with 35% phosphoric acid gel and bonded with Adper Single Bond 2 (3M ESPE) adhesive system according to manufacturer's instructions. Subsequently, the specimens were stored in deionized water at 37°C for 24h, 6 months and 1 year. Two additional teeth were used to analyze the bonding interfaces by SEM. Data was submitted to three-way ANOVA in a split plot design and Tukey's test (α = 0.05). The results showed that Ci decreased μTBS values when compared to Ca and Sd, regardless storages time or treatment. Stored samples for 6 months and 1 year decreased the pTBS for the control group, but no difference was found between storages time for the CHX group. As a conclusion, the 2% CHX application after etching showed improved dentin bond strength in the storage time, regardless of the substrates evaluated

Knowledge and precautions of light-curing composite resin restorations by dental students

Composite resin is versatile material for performing several dental procedures in dentistry, and its use has already been consolidated in this field. The clinical success of adhesive restorations is directly related to the knowledge of restorative material properties and light-curing unit factors, among others. The aim of the study was to assess the knowledge about the technical characteristics of light-curing devices and the forms of use and maintenance employed by undergraduate dental students. A total of 230 students answered a questionnaire containing six questions on technical data, use, and maintenance of light-curing units. Of the total number of participants, the majority were students from private educational institutions attending the last two years. With 59.1% of them unaware of the ideal irradiance of a light-curing unit, 73.0% were careful to position the light-curing unit as close as possible to the restoration, and 42.6% followed the light-curing time recommended by textbooks and theoretical texts. As for use and maintenance, 50.4% used the protector attached to the light-curing unit, 57.4% used safety barriers, and 63.0% sanitized the light tip after use. The evaluation suggests that student’s knowledge of “light-curing resin materials” is incomplete. Therefore, it can be inferred that the students have a good understanding of biosafety precautions when using light-curing units, but more knowledge is needed about the technical and clinical aspects of the devices