Radiopacity of bulk fill flowable resin composite materials.

OBJECTIVES: The purpose of this study was to evaluate the radiopacity of currently marketed bulk fill flowable dental composite materials (Beautifil Bulk Flowable, SDR Flow, Filtek Bulk Fill Flow, and x-tra Base Bulk Fill). MATERIALS AND METHODS: Six specimens of each material with a thickness of 1 mm were prepared, and digital radiographs were taken, using a CCD sensor along with an aluminum stepwedge and 1 mm-thick tooth slice. The mean gray level of each aluminum stepwedge and selected materials was measured, using the equal-density area tool of Kodak Dental Imaging software. The equivalent thickness of aluminum for each material was then calculated by using the stepwedge values in the CurveExpert version 1.4 program. RESULTS: The radiopacity of bulk fill flowable composites sorted in descending order as follows: Beautifil Bulk Flowable (2.96 mm Al) = x-tra base bulk fill (2.92 mm Al) = SureFil SDR Flow (2.89 mm Al) > Filtek Bulk Fill Flow (2.51 mm Al) (P < 0.05). CONCLUSIONS: As all materials had a radiopacity greater than dentin and enamel; their adequate radiopacity will help the clinicians during radiographic examination of restorations. CLINICAL SIGNIFICANCE: Bulk fill composite materials have greater radiopacity, enabling clinicians to distinguish the bulk fill composites from dentin and enamel.

Evaluation of microtensile and tensile bond strength tests determining effects of erbium, chromium: yttrium-scandium-gallium-garnet laser pulse frequency on resin-enamel bonding.

OBJECTIVES: The aim of the present study was to compare two different bond strength test methods (tensile and microtensile) in investing the influence of erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser pulse frequency on resin-enamel bonding. MATERIALS AND METHODS: One-hundred and twenty-five bovine incisors were used in the present study. Two test methods were used: Tensile bond strength (TBS; n = 20) and micro-TBS (µTBS; n = 5). Those two groups were further split into three subgroups according to Er, Cr: YSGG laser frequency (20, 35, and 50 Hz). Following adhesive procedures, microhybrid composite was placed in a custom-made bonding jig for TBS testing and incrementally for µTBS testing. TBS and µTBS tests were carried out using a universal testing machine and a microtensile tester, respectively. RESULTS: Analysis of TBS results showed that means were not significantly different. For µTBS, the Laser-50 Hz group showed the highest bond strength (P < 0.05), and increasing frequency significantly increased bond strength (P < 0.05). Comparing the two tests, the µTBS results showed higher means and lower standard deviations. CONCLUSION: It was demonstrated that increasing µTBS pulse frequency significantly improved immediate bond strength while TBS showed no significant effect. It can, therefore, be concluded that test method may play a significant role in determining optimum laser parameters for resin bonding.

Evaluation of Cytotoxicity of Dentin Desensitizing Products.

OBJECTIVES: To evaluate the cytotoxic effects of the dentin desensitizing products (DDPs) used in the treatment of dentin hypersensitivity on cultured human gingival and pulpal fibroblast cells. METHODS AND MATERIALS: The cytotoxic effects of DDPs (Smart Protect, Systemp Desensitizer, Seal & Protect, Aqua-Prep F, Isodan, Gluma, BisBlock, D/Sense Crystal, UltraEZ, Colgate Sensitive Pro-Relief, Topex, and Clinpro White Varnish) on cultured human gingival- and pulp-derived fibroblast cells were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test (Serva, Heidelberg, Germany) under two different conditions. In the first test, different dilutions of the DDPs were directly applied onto cultured gingival fibroblast cells, and in the second test, the products were applied onto different-thickness dentin discs (0.5 and 1 mm) placed above cell culture medium, which contained pulp fibroblast cells. RESULTS: According to the cytotoxicity evaluations of gingival fibroblast cells, the cytotoxicity of all of the DDPs was very high at 50% concentrations (p<0.05). Colgate Sensitive Pro-Relief, Clinpro White Varnish, and Topex showed higher cytotoxicity than did the other products (p<0.05), decreasing with further dilutions, and these products were found to be less cytotoxic to both types of cells (p<0.05) than were the other products with further dilutions. The cytotoxicity to human gingival and pulpal fibroblast cells of Systemp Desensitizer, Aqua-Prep F, Isodan, and Gluma did not show any decrease with further dilutions, and these products were found to be more cytotoxic than the other products (p<0.05). CONCLUSIONS: According to the findings of this study, Colgate Sensitive Pro-Relief, Topex, and Clinpro White Varnish were less cytotoxic than the other DDPs used in this study.

The effect of a new calcium-based agent, Pro-Argin, on the microhardness of bleached enamel surface.

BACKGROUND: This study investigated the effects of Pro-Argin application on the microhardness of bleached enamel and compared them with those of acidulated phosphate fluoride (APF) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) applications. METHODS: Forty blocks (4 × 4 × 4 mm) were prepared from the facial surfaces of 10 sound bovine incisors. The enamel surfaces were bleached with 35% hydrogen peroxide three times at 5-day intervals. The specimens were divided into five treatment regimen groups (n = 8 each): Group 1, bleaching/no surface treatment (control); Group 2, bleaching/Pro-Argin toothpaste treatment; Group 3, bleaching/Pro-Argin treatment; Group 4, bleaching/APF treatment; and Group 5, bleaching/CPP-ACP treatment. During bleaching treatments, specimens were stored in artificial saliva. Vickers microhardness measurements were performed at baseline and after treatment in all groups. Statistical analyses were performed using the paired t-test, one-way analysis of variance, and post hoc least significant difference tests. RESULTS: After bleaching, hardness values of enamel surfaces increased significantly in the treatment groups versus the control group (p < 0.05). However, no significant difference was found among treatment groups (p > 0.05). CONCLUSIONS: Through bleaching treatment, Pro-Argin application may have a positive effect on enamel surface hardness, equivalent to that of CPP-ACP or APF.

Efficacy of several techniques for the removal of calcium hydroxide medicament from root canals.

AIM: To compare the efficacy of several techniques for the removal of calcium hydroxide (Ca(OH)(2)) from root canals. METHODOLOGY: The root canals of 24 freshly extracted human mandibular premolars were prepared with ProTaper rotary instruments. The teeth were sectioned longitudinally along the length of the instrumented canals. The roots were subsequently reassembled with wires. After Ca(OH)(2) was placed into the canals, four techniques were used for its removal. In Group I, the teeth were irrigated with 5 mL of 2.5% NaOCl. Group II was treated in the same manner as Group I, but 5 mL of 17% EDTA was used in addition to NaOCl. In Group III, the teeth were irrigated with 5 mL of 2.5% NaOCl and agitated by an ultrasonic unit. In Group IV, the teeth were irrigated with 5 mL of 2.5% NaOCl and a CanalBrush was used to remove the Ca(OH)(2) . The roots were disassembled and digital photographs were taken. Measurements of residual Ca(OH)(2) were performed as percentages of the overall canal surface area. The data was analysed with one-way ANOVA with post hoc Tukey test. RESULTS: Significantly less residual material was obtained with a CanalBrush and passive ultrasonic agitation of NaOCl than the other groups (P < 0.05). There was no significant difference between syringe delivery of NaOCl and NaOCl+EDTA (P > 0.05). CONCLUSIONS: None of the techniques removed the Ca(OH)(2) dressing completely. CanalBrush and ultrasonic agitation of NaOCl were significantly more effective than irrigant-only techniques.

Pain perception during inferior alveolar injection administered with the Wand or conventional syringe.

OBJECTIVE: This study compared a computerised device (the Wand) with a conventional syringe in terms of the pain of needle insertion and injection during inferior alveolar nerve (IAN) block injection. METHODS AND MATERIALS: The subjects were 40 patients between the ages of 18 and 30 years requiring local anaesthesia for dental restoration in the mandible. Before anaesthetic administration, the patients' anxiety levels were determined. Contralateral IAN injections were administrated at two separate appointments with random use of either the Wand or a conventional syringe. Following the injection, the patients used both the pain rating score (PRS) and a visual analogue scale (VAS) to assess the intensity of pain. RESULTS: When pain was measured after the injection, the Wand was found to be less painful than the syringe for the pain of both needle insertion and injection (p <0.05). CONCLUSION: The Wand technique resulted in significantly lower pain scores during the IAN block injections. Most of the patients preferred the IAN injection with the Wand for future dental injections.

Bond strength of total-etch and self-etch dentin adhesive systems on peripheral and central dentinal tissue: a microtensile bond strength test.

OBJECTIVE: The purpose of this study was to evaluate the microtensile bond strength (mu TBS) of four total-etch adhesives [Excite (EB), Prime&Bond NT (PBNT), Single Bond (SB), and One Coat Bond (OCB)] by comparing them to five self-etching adhesives (Clearfil SE Bond (CSEB), Xeno III (X III), Prompt L-Pop (PLP), AQ Bond (AQB), and Tyrian/One Step plus (TOSP)] at different dentinal areas. In addition the interface between the adhesive resins and dentin was examined using scanning electron microscopy (SEM). METHODS AND MATERIALS: Superficial occlusal dentin of extracted human molars was exposed and finished with wet 800-grit silicon carbide paper. A block of composite resin was then bonded to the molar samples with the above adhesives according to the manufacturers' instructions. After 24 hours in water at 37 degrees C, the specimens were sectioned into 1 mm thick slices and divided into two regional subgroups according to their relationship to pulp tissue using visual criteria: pulp center and pulp periphery. The slices were then trimmed for the microtensile bond test and subjected to a tensile force and crosshead speed of 1 mm/min. Two-way analysis of variance was performed for statistical analyses. In addition the bond strengths for nine adhesive systems for each dentinal area were compared using the Post-Hoc test. The resin-dentin interfaces for each adhesive system were observed under a SEM. RESULTS: Mean mu TBS ranged from (25.2 MPa) for TOSP to (48.9 MPa) for PBNT. The bond strengths of total-etch adhesive systems were not significantly different, and were higher than self-etch adhesive systems, except for CSEB (p<0.05). No significant regional difference was observed for all of the nine adhesive systems (p>0.05). SEM observation showed there is not a standard hybridization for adhesive systems. CONCLUSION: Different dentinal areas may not exhibit as great an influence on bond strengths using new adhesive systems.