Photobiomodulation therapy and 3% potassium nitrate gel as treatment of cervical dentin hypersensitivity: a randomized clinical trial.

OBJECTIVES: This randomized controlled trial aimed to evaluate different protocols for dentin hypersensitivity treatment with low-power lasers and desensitizing agents, and the association between low-power lasers and desensitizing agents. MATERIALS AND METHODS: Fifty-four patients (303 teeth) were randomly allocated to three groups: G1, 3% nitrate potassium gel, UltraEZ (n = 17); G2, photobiomodulation therapy (PBM) with a low-level infrared laser (n = 17), 100 mW, spot size of 0.028 cm2, and dose of 1 J per point; and G3, nitrate potassium + PBM (n = 20). Treatments were applied to the buccal cervical region at intervals of 72 h, and all protocols were performed in three sessions. The patients' response to evaporative stimuli was rated using the visual analog scale (VAS). Re-evaluations were performed immediately after each application and 1 week, 1 month, and 3 months after treatment. A two-way repeated measures test and Tukey's post hoc test were used for multiple comparisons (α = 5%). RESULTS: There was a reduction in pain levels at the end of treatment in all groups. There were no significant differences in VAS score changes between the groups immediately after treatment and after the third month, compared to the baseline (p > 0.05). CONCLUSION: Under the limitations of this in vivo study, the proposed three-session protocol was effective in reducing dentin hypersensitivity after 3 months, regardless of the desensitization mechanism used. Conservative and long-term protocols are interesting for the control of pain caused by dentin hypersensitivity. CLINICAL RELEVANCE: The increase in cervical dentin hypersensitivity prevalence warrants easy-to-apply and long-lasting desensitizing protocols for pain control.

Four-Session Protocol Effectiveness in Reducing Cervical Dentin Hypersensitivity: A 24-Week Randomized Clinical Trial.

Objective: A single-blind randomized clinical trial was conducted to evaluate the effectiveness of desensitizing agents with different action mechanisms in reducing cervical dentin hypersensitivity (CDH) after four application sessions, with 24-week follow-up. Materials and methods: Sixty patients with CDH were selected in the study and were allocated in three groups of treatment: Desensibilize KF 2%, Clinpro XT Varnish, and Photon Lase III (100 mW, 4 J/cm2-1 J/cm2 each point, 10 sec per point with wavelength of 808 nm). There were four application sessions performed, with a 48-h interval between each one. The evaporative stimuli and visual analog scale were used to evaluate the CDH level at baseline, immediately after treatment, and at 2, 4, 8, and 24 weeks after the application. Mixed-model effects test was used for comparison (α = 0.05).Results: All three groups showed significant reduction in CDH from baseline to each all-subsequent follow-up. All the groups maintained the CDH reduction, and presented no statistical differences between each other after treatment (p = 0.885), 2 (p = 0.857), 4 (p = 0.928), 8 (p = 0.206), and 24 weeks (p = 0.073) of follow-up.Conclusions: The four-session protocol was an effective approach in reduction of CDH (even after 24 weeks), regardless of desensitization mechanism.

In vitro study of fracture load and fracture pattern of ceramic crowns: a finite element and fractography analysis.

PURPOSE: This in vitro study investigated the null hypothesis that metal-free crowns induce fracture loads and mechanical behavior similar to metal ceramic systems and to study the fracture pattern of ceramic crowns under compressive loads using finite element and fractography analyses. MATERIALS AND METHODS: Six groups (n = 8) with crowns from different systems were compared: conventional metal ceramic (Noritake) (CMC); modified metal ceramic (Noritake) (MMC); lithium disilicate-reinforced ceramic (IPS Empress II) (EMP); leucite-reinforced ceramic (Cergogold) (CERG); leucite fluoride-apatite reinforced ceramic (IPS d.Sign) (SIGN); and polymer crowns (Targis) (TARG). Standardized crown preparations were performed on bovine roots containing NiCr metal dowels and resin cores. Crowns were fabricated using the ceramics listed, cemented with dual-cure resin cement, and submitted to compressive loads in a mechanical testing machine at a 0.5-mm/min crosshead speed. Data were submitted to one-way ANOVA and Tukey tests, and fractured specimens were visually inspected under a stereomicroscope (20×) to determine the type of fracture. Maximum principal stress (MPS) distributions were calculated using finite element analysis, and fracture origin and the correlation with the fracture type were determined using fractography. RESULTS: Mean values of fracture resistance (N) for all groups were: CMC: 1383 ± 298 (a); MMC: 1691 ± 236 (a); EMP: 657 ± 153 (b); CERG: 546 ± 149 (bc); SIGN: 443 ± 126 (c); TARG: 749 ± 113 (b). Statistical results showed significant differences among groups (p < 0.05) represented by different lowercase letters. Metal ceramic crowns presented fracture loads significantly higher than the others. Ceramic specimens presented high incidence of fractures involving either the core or the tooth, and all fractures of polymer crown specimens involved the tooth in a catastrophic way. Based on stress and fractographic analyses it was determined that fracture occurred from the occlusal to the cervical direction. CONCLUSIONS: Within the limitations of this study, the results indicated that the use of ceramic and polymer crowns without a core reinforcement should be carefully evaluated before clinical use due to the high incidence of failure with tooth involvement. This mainly occurred for the polymer crown group, although the fracture load was higher than normal occlusal forces. High tensile stress concentrations were found around and between the occlusal loading points. Fractographic analysis indicated fracture originating from the load point and propagating from the occlusal surface toward the cervical area, which is the opposite direction of that observed in clinical situations.

Surface treatment protocols in the cementation process of ceramic and laboratory-processed composite restorations: a literature review.

UNLABELLED: The clinical longevity of indirect restorations made of ceramics or indirect composite resins depends on their successful treatment and cementation. The cementation technique is determined by the type of restorative material-ceramics or indirect composite resins; thus, their intaglio surface treatment should be performed according to their particular compositions. The aim of this literature review was to define surface treatment protocols of different esthetic indirect restorative materials. A PubMed database search was conducted for in vitro studies pertaining to the most common treatment protocols of tooth-colored materials. Articles that described at least the surface treatment procedure, its effects on adhesion, its relationship with the material's composition, clinical aspects, and expected longevity were selected. The search was limited to peer-reviewed articles published in English between 1965 and 2004 in dental journals. Sandblasting, etching techniques, and silane coupling agents are the most common procedures with improved results. CLINICAL SIGNIFICANCE: Tooth-colored restorative materials vary considerably in composition and require different protocols for adhesive cementation.