Clinical evaluation of microhybrid composites in noncarious cervical lesions: 24‑month results

Objective: To evaluate the clinical performance of two different microhybrid resin composites in noncarious cervical lesions (NCCLs) after 24 months.Subjects and Methods: Ninety‑seven NCCLs were restored with either TPH Spectrum (n = 48) or Filtek Z250 (n = 49) using an etch‑and‑rinse adhesive in 20 patients. The restorations were clinically evaluated using modified United States Public Health Service criteria for retention, color match, marginal discoloration, marginal adaptation, surface texture, anatomic form, postoperative sensitivity, and secondary caries. The restorations were assessed 1 week after placement (baseline) and after 6, 12, and 24 months. Restoration survival rates were calculated using the Kaplan– Meier procedure estimator, and a log‑rank test was used to compare the survival distributions (P < 0.05). Statistical analysis was undertaken using Pearson’s Chi‑square test and Fisher’s exact test to assess differences among the restorative materials (P < 0.05). Cochran’s Q‑test was employed for evaluating differences in the same restorative material between recall periods.Results: The retention rates were 100% at 6 months, 89.6% and 91.8% at 12 months, and 85.4% and 89.8% at 24 months for TPH and Z250, respectively. TPH showed a statistically significant difference in marginal discoloration between the baseline and 24 months results (P < 0.05). Both TPH and Z250 showed statistically significant differences in marginal adaptation between the baseline and 24 months results (P < 0.05).Conclusion: Over the 24‑month period, both microhybrid resin composites demonstrated acceptable clinical results in NCCLs.Key words: Clinical evaluation, microhybrid resin composites, modified United States Public Health Service criteria, noncarious cervical lesion

Effect of desensitizing tooth pastes hn dsfferent restorative materials' bond strength to coronal and root dentin

Aim: The aim of the study was to evaluate the effects of two desensitizing tooth-pastes on the shear bond strength of resin composite and glass ionomer restorative materials to coronal and root dentin. Materials and Methods: 108 human third molars' distal or mesial sides were ground flat with a silicon-carbide paper. The samples were randomly divided into 3-major groups (N=36) to be brushed with: GroupA: Sensodyne Rapid Relief; GroupB: Colgate Sensitive Pro-Relief; GroupC: Colgate Total 12 toothpastes. Brushing was performed with tooth brushing simulator 2 times/day for 10 days with 10 strokes/brushing. They were further divided into three sub-groups (n=12) to receive the following adhesion protocols to coronal/root dentin. Group1: Clearfil SE Bond + Filtek Z250 Composite; Group2: Adper Single Bond2 + Filtek Z250Composite; Group3: Riva Glass Ionomer Cement. Samples were kept in distilled water for 24 hours. Shear bond strength test was performed with Universal Test Machine (cross head speed: 0.5 mm/sec). The data were evaluated statistically. Results: For all restorative techniques evaluated, the least shear bond strength values were obtained after Sensodyne Rapid Relief usage.Riva Glass Ionomer Cement demonstrated statistically significant inferior shear bond strength values than resin composite. Conclusion: Self-etch systems may be the choice for adhesion after desensitizing toothpaste usage. © 2018 Cumhuriyet University Faculty of Dentistry

Shear Bond Strength of Different Adhesive Systems in Amalgam Repair

The purpose was to evaluate the effect of different adhesive systems on shear-bond-strength between amalgam and resin composite. 48 amalgam specimens were condensed into plastic tubes (4 mm diameter x 5 mm height). The specimens were kept in incubator for 24 h at 37 degrees C, aged by thermal cycling 1000 times between 5-55 degrees C. The specimens' surfaces were finished with coarse diamond burs and randomly divided into 4 groups (n = 12) with respect to different surface conditioning methods: etchant+universal adhesive (All-Bond Universal, Bisco), universal adhesive, alloy primer (Z-Prime, Bisco)+universal adhesive, self-adhesive resin cement (BisCem, Bisco). The old amalgam specimens were placed into plastic tubes (4 mm diameter x 8 mm height) and all adhesive systems were used according to manufacturer's instructions. Resin composite (Charisma Classic, Haraeus Kulzer) was placed and polymerized 20 s. The samples were incubated in distilled water at 37 degrees C for 24 h prior to the shear-bond-strength test. The shear-bond-strength test was accomplished using a universal testing device. Statistical analyzes were made with One-way ANOVA and Tukey HSD tests. There was no significant difference between self-adhesive resin cement and alloy primer applied groups but showed better bond strength values than self-etch and etch&rinse adhesive applied groups. The application of self-adhesive resin cement and alloy primer+universal adhesive in amalgam repair exhibited successful outcomes

Influence of operator experience on bond strength of different adhesives to dentin

Aim: Application of adhesive systems on dentin is a multistep, technique-sensitive procedure. Thus, the aim was to assess the effect of operator experience on the shear bond strength of an etch-and-rinse adhesive system and a self-etch adhesive system on dentin. Materials and Methods: Forty-eight extracted human molar teeth were used in the study. They were embedded in an acrylic resin after cutting off the roots. The mesial and distal enamels of the teeth were removed to expose dentin surfaces. The samples were allocated to four groups (n = 12): Group 1: restorative dentistry specialist with 13 years of experience, Group 2: with 6 years of experience, Group 3: postgraduate operator with 2 years of experience, and Group 4: undergraduate student with 1 year of experience and familiar with adhesive with systems. Each operator applied an etch-and-rinse adhesive system (Adper Single Bond 2) to mesial surface and a self-etch adhesive system (Clearfil SE Bond) to distal surface (n = 12). Then, a composite resin (Filtek Z250) was inserted with the aid of a plastic ring (2 mm 2 mm) and light polymerized. The specimens were stored in distilled water before shear bond strength test. A two-way ANOVA test was used for statistical analysis. Results: No statistically significant difference was found between each operator type with respect to etch-and-rinse adhesive system (P 0.05); however, the undergraduate student performed better than 2-year experienced operator with respect to self-etch system application (P 0.05). Conclusion: The shear bond strength of a self-etch system might vary according to the operator's experience. © 2020 Journal of Conservative Dentistry Published by Wolters Kluwer-Medknow

Choice of Parameters for the Electrodrive Diagnostic System of Hybrid Vehicle Traction

When operating a hybrid vehicle (HEV), it is important to reduce maintenance and repair costs. The HEV electric drive (ED) consists of electronic, electrical and mechanical parts and is considered a complex diagnostic model. The availability of an electrical part greatly simplifies the process of monitoring and obtaining information about the state of the system. In order to create a hybrid diesel-electric propulsion system (HDEPS), the choice of structural and functional parameters as diagnostic ones is justified, the control points are chosen, and the necessary accuracy and unambiguity of measurements are determined. Qualitative evaluations of the electrical processes occurring in the power supply circuit of ED from a high-voltage accumulator battery for the selection of diagnostic parameters according to the criteria of sensitivity, informative character, stability and manufacturability of measurements are presented. It has been revealed that during HDEPS diagnostics both stable and transient modes of operation of electric machines should be considered; for analysis of ED technical state it is necessary to have information about current mode of HDEPS load; for measurement of instantaneous values of supply voltage and consumption current it is necessary to select the sensors with short response time and linear conversion function. In terms of sensitivity to structural changes in the circuit and parametric deviations, it is necessary to choose, as diagnostic parameters, the voltage or current, depending on the mode of operation of the ED and the point of measurement of the electrical value. The obtained results are the basis for creating a new system of diagnostics of electric power supply HDEPS in this direction