Influence of surface treatments on the bond strength of metal brackets to CAD/CAM materials and discoloration after various refinishing procedures : Scanning electron microscopy and atomic force microscopy study.

PURPOSE: This study evaluated the shear bond strength (SBS) of a metal bracket bonded to three different computer-aided design/computer-aided manufacturing (CAD/CAM) restoration materials pretreated with different surface treatments. In addition, the surface topography and color change of the restorations after debonding with two different tungsten carbide burs were examined. METHODS: A total of 216 plates were cut from three different CAD/CAM blocks, each of which was divided into three subgroups with different pretreatment methods: (1) acid etching, (2) sandblasting, and (3) laser irradiation. Incisor metal brackets were bonded. The SBS test was performed, and the failure types were classified. Then, samples were randomly divided into two subgroups according to the adhesive removal procedure to be used: a tungsten carbide bur with 12 blades or 24 blades (n = 12). Color change was calculated based on the ∆E00, and surface morphology was evaluated via SEM and AFM analysis. RESULTS: The SBS data revealed that the type of CAD/CAM material and the applied surface treatment significantly affected bond strength. The highest SBS values were detected for the Grandio Blocs (VOCO GmbH, Cuxhaven, Germany; 14.3 ± 4.4 MPa), and the lowest was observed for Cerasmart (GC Europe, Leuven, Belgium; 12.0 ± 4.0 MPa). The ∆E00 results demonstrated significant differences only as a result of the applied surface treatment. The ∆E00 value in all groups was above the 1.77 threshold. CONCLUSION: CAD/CAM material types and surface treatments affected the bond strength, but the interactions of these factors did not. The chosen surface treatment also significantly affected the ∆E00 after the polishing was done.

Evaluation of the effectiveness of current disinfection methods in complete denture patients.

OBJECTIVES: Candida adherence to the denture base is an important cause of denture stomatitis in elderly and handicapped patients where effective patient- and physician-based disinfection methods are required. The purpose of this study was to investigate the in vivo effectiveness of chemical and physicochemical methods and their combinations against common oral Candida species on denture base acrylic resin. METHOD AND MATERIALS: Patients were divided into six groups according to disinfection methods. For chemical disinfection, chlorhexidine, sodium hypochlorite, and glutaraldehyde were used by the patients. Microwave and ozone therapy were applied by physicians for physicochemical disinfection. Fungal load count was performed. This procedure was repeated before applying any disinfection procedures, at 1 week and 1 month after the patient started to use the relevant chemical disinfectant and apply physicochemical methods. A multivariate analysis test was used to determine the change in fungal load over time and whether this change led to a difference among the groups (P < .05). RESULTS: The most frequently isolated Candida strain was Candida albicans. The change in fungal load over time was significantly different (P < .001). However, the difference between the groups did not show any significant difference in the paired comparison analyses of the chemical disinfection groups (P >.05). No Candida strains were detected in either physicochemical method at any of the control time points. CONCLUSIONS: The study concluded that chemical disinfectants used by patients were effective for but total eradication of Candida adhesion requires the use of additional ozone or microwave therapy.

Evaluation of gingival displacement methods in terms of periodontal health at crown restorations produced by digital scan: 1-year clinical follow-up.

The purpose of this clinical study was to compare the effects of the gingival displacement techniques of retraction cord, cordless paste system, and Er,Cr:YSGG laser troughing on the periodontal tissues around the crown restoration produced using a digital scan. This was analyzed by recording the probing depth (PD), plaque index, gingival index (GI), mobility, sensitivity, and bleeding on probing (BOP) index. This study included 60 mandibular 1st molars from 52 participants (20 males and 32 females) requiring crown restoration. The margin lines of the crown preparations were placed 1 mm subgingivally. Based on the gingival displacement technique used, the patients were divided into three groups: retraction cord, cordless paste system, and Er,Cr:YSGG laser troughing. A digital scan of the prepared tooth was performed. Follow-up appointments were scheduled at five different times: 1st day, 1st month, 3rd month, 6th month, and 1st year. Six periodontal indices were used to assess the periodontal health. The chi-square test was used to compare categorical variables depending on the groups. There was a significant difference in the PD, GI, and BOP index scores among the three techniques during the 1-year clinical monitoring (p < 0.001). The PD in the three zones of the buccal surface showed a significant increase with time in the retraction cord and cordless paste system groups (p < 0.001). The highest GI scores were observed in the retraction cord group on the 1st day. The Er,Cr:YSGG laser troughing procedure produced lower PD, GI, and BOP index scores as compared to the retraction cord and cordless paste system procedures in the 1-year period.

Evaluation the effects of low-level laser therapy on disc displacement with reduction.

OBJECTIVES: This study aims to evaluate the effects of additional low-level laser therapy (940 nm GaAlAs) to the routine occlusal splint therapy on maximal mouth opening (MMO), visual analog scale (VAS) scores, and passive mouth opening (PMO). PATIENTS AND METHODS: Between January 2016 and March 2018, a total of 40 patients (10 males, 30 females; mean age 22.35 years; range, 18 to 60 years) with disc displacement with reduction of the temporomandibular joint were included. The patients were divided into two groups. Group 1 (control group, n=20) received routine non-steroidal anti-inflammatory drug (NSAID) therapy and occlusal splint therapy for eight hours per day for a total of three months. Group 2 (laser group, n=20) received NSAID, occlusal splint therapy and 940 nm wavelength diode laser therapy for two sessions per week for a total of four weeks. The MMO, PMO, and VAS scores were recorded before and at one, two, three, four, and 12 weeks after treatment. The joint and muscle examinations were performed. RESULTS: A constant decrease was found in the VAS scores in both groups. At four (p=0.008) and 12 weeks (p=0.003), a statistically significant difference in the VAS scores was observed. At all time points, PMO and MMO scores increased in both groups. The MMO scores were statistically higher in the laser group at all time points (p<0.005). CONCLUSION: Our study results suggest that short-term low-level laser therapy additional to conventional treatment may yield satisfactory outcomes.