Ultrasonic activation of adhesive systems increases bond strength and intratubular penetration of resin cement in root dentin subjected to radiation therapy.

OBJECTIVE: This study aimed to evaluate the effect of ultrasonic activation of etch-and-rinse and self-etch adhesive systems on the bond strength of resin cement to irradiated root dentin. MATERIALS AND METHODS: Eighty human maxillary anterior teeth were distributed into 8 groups (n = 10), according to the type of adhesive system used (etch-and-rinse and self-etch), the ultrasonic activation of the adhesive systems, and the dentin condition (irradiated or non-irradiated - 70 Gy). Endodontic treatment was performed followed by fiberglass post-space preparation. After fiberglass posts' luting, the roots were transversely sectioned on dentin discs and submitted to the push-out bond strength test (0.5 mm/min). The fractured specimens were analyzed under a stereomicroscope and Scanning Electron Microscope (SEM) for failure mode classification. One of the dentin discs was analyzed under SEM to evaluate the characteristics of the adhesive interface. RESULTS: Irradiated specimens had lower bond strength than non-irradiated specimens (P < 0.0001). Ultrasonic activation of both adhesive systems increased the bond strength of the resin cement to irradiated dentin (P < 0.0001). Radiotherapy significantly affected the failure mode in the middle (P = 0.024) and apical thirds (P = 0.032) (adhesive failure). CONCLUSION: Non-irradiated specimens had a more homogeneous adhesive interface. When ultrasonically activated, both adhesive systems showed a greater number of resinous tags, regardless of the dentin condition. CLINICAL RELEVANCE: Ultrasonic activation of adhesive systems is a feasible strategy to enhance fiberglass posts retention in oncological patients.

Assessing push-out bond strength in re-irradiated teeth: Universal resin cement performance in self-etch and self-adhesive modes.

OBJECTIVES: To investigate the effect of cumulative doses of radiation on the pushout bond strength (BS) of a universal resin cement used in the self-etch (SE) and self-adhesive (SA) modes to the intraradicular dentin. MATERIALS AND METHODS: Forty-eight human teeth were distributed into three groups (n = 16) according to the radiation therapy dose (RT): NoRT (no-radiotherapy), 70RT (70 Gy), and 70 + 70RT (70 Gy + 70 Gy). The teeth were redistributed into two subgroups (n = 8), according to the adhesive mode: SE (NoRT-SE, 70RT-SE, and 70 + 70RT-SE) and SA (NoRT-SA, 70RT-SA, and 70 + 70RT-SA). Data were statistically compared after BS test (ANOVA, Tukey's post hoc test, and Fisher's exact test). RESULTS: In the SA mode, BS was significantly higher in nonirradiated teeth compared with 70RT and 70 + 70RT (p < 0.0001). There were no significant differences between SE and SA modes in nonirradiated teeth (p = 0.14). In the 70RT group, SE mode increased BS compared with SA mode (p < 0.0001). Most specimens had adhesive and mixed failures in SA and SE modes, respectively. CONCLUSIONS: The universal resin cement in the SE mode had greater BS to the irradiated dentin. When teeth were re-irradiated, the universal resin cement had similar performance in terms of BS, regardless of the adhesive approach. CLINICAL SIGNIFICANCE: There is no research establishing a correlation between radiotherapy and its impact on the BS of a universal resin cement used in SE and SA modes to intraradicular dentin.

Effect of the timing of radiation therapy on the push-out strength of resin cement to root dentine.

This study investigated the effect of radiation timing on the bond strength of resin cement to intraradicular dentine. Fifty human teeth were distributed into 5 groups (n = 10): Control (nonirradiated teeth), Before-RCT (teeth irradiated before root canal treatment), After-CH (teeth irradiated after canal preparation and placement of calcium hydroxide intracanal dressing), After-RCT (teeth irradiated after completion of root canal treatment) and After-FPL (teeth irradiated after luting of a glass fibre post). Each tooth received 70 Gy irradiation. The roots were sectioned for push-out strength testing. After-RCT and After-FPL groups had significantly lower push-out strength than the control at the middle third (p < 0.05). Control and After-CH groups had a higher percentage of cohesive dentine failure. Radiotherapy after root canal obturation and post luting adversely affected the adhesiveness of resin cement to intraradicular dentine. Teeth irradiated before root canal treatment and after placement of calcium hydroxide had the best performance.

Effect of root perforation repair with mineral aggregate-based cements on the retention of customized fiberglass posts.

The purpose of this study was to investigate whether the root perforation repair with mineral aggregate-based cements affects the retention of customized fiberglass posts to bovine intraradicular dentin. Sixty-four bovine mandibular incisors had their root canals endodontically treated and prepared for fiberglass posts luting. Teeth were randomly distributed into four groups (n = 16), according to the cement used for the perforations repair (MTA HP; calcium aluminate cement-CAC; and CAC + calcium carbonate nanoparticles-nano-CaCO3) and control group (no perforation). The groups were redistributed according to the fiberglass posts luting protocol (n = 8): total-etching (TE) (MTA HP/TE; CAC/TE; CAC + CaCO3/TE and control/TE) and self-etching (SE) (MTA HP/SE; CAC/SE; CAC + CaCO3/SE and control/SE). Roots were sectioned into 1.3 mm-thick dentin slices obtaining samples that were submitted to the push-out test in Universal Testing Machine (Instron, Model 4444-0.5 mm/min). The fractured samples were analyzed under stereomicroscope and Scanning Electron Microscope (SEM). CAC/TE and CAC/SE groups had significant difference between the cervical and middle thirds (p < 0.05). When the root thirds were not considered, CAC/SE had the lowest bond strength and differed statistically from CAC/TE and CAC + CaCO3/TE groups, which had the highest mean bond strength values (p < 0.05). The root perforations repair did not affect the bond strength of resin cement/customized fiberglass posts to bovine dentin. The increase in bond strength is luting protocol dependent.

Clareamento interno/externo para dentes desvitalizados / Inside/Outside bleaching of nonvital teeth

A alteração de cor dos dentes isolados pode impactar negativamente na autoestima dos indivíduos, portanto é necessária a seleção de um tratamento adequado para a resolução de cada caso. Este caso clínico objetivou demonstrar o tratamento de um dente isolado com descoloração dental mediante clareamento dental do tipo interno/externo. O procedimento consistiu na realização do tratamento clareador do tipo interno/externo no dente escurecido e tratamento clareador caseiro nos demais dentes. O resultado apresentou-se satisfatório, especialmente pelo fato de ser uma opção de tratamento conservadora, efetiva e de custo-benefício favorável, a qual permite que opções menos conservadoras, como coroas e facetas, possam ser realizadas futuramente, caso houver necessidade.

Single discolored tooth can impact negatively the self-esteem of the individual, therefore selecting the most appropriate treatment for the resolution of each case is necessary. The aim of this case report was to demonstrate the treatment of a single discolored tooth, through the inside/ouside bleaching technique. Treatment planning consisted in internal/external bleaching of the single discolored tooth and home bleaching technique of the other teeth. A satisfactory result was obtained, in addition to being a conservative, effective and cost-effective treatment option. This allows for less conservative options, such as crowns and veneers, to be performed in the future, if necessary.

Nanofilled composite restorations with different adhesives strategies: clinical cases.

The esthetic procedures with composites are widely applied, both to posterior and anterior teeth to restore caries cavities, to replace failed restorations, or to make cosmetic procedures. The materials selected to each case may make the difference in the clinical result. This paper presents two clinical cases made with a nanofilled composite resin system used in different bond strategies. In the first, a wide posterior class I restoration, the self-etching strategy was used. The second, an esthetic anterior restoration, was made using the prior etching with phosphoric acid and a hydrophobic adhesive.