Mustafa Öksüz

Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

Objective The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. Material and Methods Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Students t-test. The failure modes of all groups were also evaluated. Results The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. Conclusion The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.

Thermal and mechanical properties of composite nanofiber webs and films containing cellulose nanowhiskers

In this study, nanocomposites reinforced with cellulose nanowhiskers (CNWs) were prepared by employing three different fabrication methods. These methods include electrospinning of nanofiber webs using a single-component nozzle, electrospinning of nanofiber webs using a coaxial bi-component nozzle, and film casting followed by compression molding. Maleic anhydride grafted elastomeric polymer was used as the polymer matrix. Nanocomposite samples obtained from these three different systems were characterized in terms of morphology, and mechanical and thermal properties. The processing–structure–property relationships of the nanocomposites are discussed in this paper.

Shear Bond Strength of Indirect Composites Luted with Three New Self-Adhesive Resin Cements to Dentin

The aim of this study was to evaluate the shear bond strengths of indirect composites (those cured outside the mouth) luted by three different, recently developed, self-adhesive resin cements to dentin. Seventy caries-free mandibular third molar teeth embedded in acrylic resin and with exposed dentin surfaces were used. Teeth were randomly divided into seven groups. The following application protocols were carried out: a) Group 1 (control group)—direct composite resin restoration (Alert) with total-etch adhesive system (Bond 1 primer/adhesive); b) Group 2—indirect composite restoration (Estenia) luted by a resin cement (Cement-It) combined with the same total-etch adhesive; c) Group 3—direct composite resin restoration with self-etch adhesive system (Nano-Bond); d) Group 4—indirect composite restoration luted by the resin cement combined with the same self-etch adhesive; e) Groups 5–7—indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem®, Maxcem®, and Embrace WetBond®, respectively) onto untreated dentin surfaces. Shear bond strengths of the groups were performed with a universal testing device. Results were statistically analysed by student-t and one way ANOVA tests. The fractured surfaces were also examined by SEM. The indirect composite restorations luted with the self-adhesive resin cements (Groups 5–7) showed successful results compared with the other groups (p < 0.05). Group 4 showed the weakest bond strength (p > 0.05). Open dentin tubules were observed on the total-etch adhesive applied surfaces whereas a smear rich layer was found by SEM on the self-etch adhesive applied surfaces. The new universal self-adhesive resins may be considered an alternative for luting the indirect composite restorations onto the untreated dentin surfaces.

Kompozit Nanolif ve Isı Uygulanmış Nanoliflerin Üretim ve Analizi

In this study, two different applications related with nanofiber production have been studied. In one application, nanofiber was obtained from Maleic Anhydrite grafted Polypropylene (MAH PP) that it is not possible to produce nanofiber at the environmental temperature by solvent technique. The effect of the temperature of polymer solvent on nanofiber producibility has been investigated. It has been seen that it is not possible to produce nano fiber by o o solvent below 70 C. The bead on the nanofiber increases when solution temperature is around 100 C. Bead formation may be due to lower viscosity resulted from higher temperature. In the other application, elastomeric polymer (Polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene graft-maleic anhydride) (SEBS-g-MA) together with cellulose nanowhiskers (CNW) was used to produce composite nanofiber. The effect of feed rate and also the amount of water content on properties of composite nanofiber have been investigated. It has been seen that an increase of water content results to deformation of nanofiber morphology and decrease of feeding rate results to thinner fiber.