Biomedical subjects

Luiz André Freire Pimenta

Publications and source records attributed to Luiz André Freire Pimenta.

At least 19 recordsLinked to original sources

PubMed2006

The effect of light-curing source and mode on microtensile bond strength to bovine dentin.

PURPOSE: The purpose of this study was to evaluate the effects of different light-curing techniques on the microtensile bond strength of hybrid and packable resin composite to dentin. The null hypotheses were that different light-curing techniques do not affect the adhesion of resin composites to tooth structure and that different resin composites do not have a similar bond to dentin. MATERIALS AND METHODS: One hundred four box-shaped buccal preparations were made and dentin/enamel adhesive was applied according to the manufacturer's instructions (Single Bond 3M ESPE). A hybrid resin composite (Filtek Z250, A2, 3M ESPE) or a packable resin composite (Solitaire 2, A2, Heraeus Kulzer) were inserted in bulk and polymerized using one of these techniques (n = 13): (a) Soft-start (SS) using a halogen lamp (QTH); (b) LED low intensity; (c) Plasma arc (PAC) curing for 6 s for packable resin composite and 3 s for the hybrid resin composite; (d) Conventional (C) QTH curing for 40 s. Afterwards, specimens were thermocycled 1,000 times between 5 degrees C and 55 degrees C in tap water, and were sectioned into beams with a rectangular cross-sectional area of approximately 1 mm2. Microtensile bond strength testing was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. RESULTS: Bond strength means +/- (SD) in MPa were: Filtek Z250: SSQTH = 17.9 (5.4); LED = 17.9 (6.4); PAC = 16.8 (6.8); CQTH = 16.1 (4.6). Solitaire 2: SSQTH = 12.4 (6.4); LED = 15.5 (4.3); PAC = 16.2 (4.4); CQTH = 13.8 (5.7). The data were structured in a split-plot design and analyzed by a two-way ANOVA and Tukey's tests (alpha = 0.05). CONCLUSION: The light-curing method did not significantly affect bond strengths. However, the bond strengths of the packable resin composite were significantly lower than those of the hybrid resin composite for all polymerization techniques, suggesting that the restorative material itself might be a more critical factor in adhesion than the curing method.

Acrylic Resins↗

PubMed2006

Influence of different tests used to measure the bond strength to dentin of two adhesive systems.

PURPOSE: To investigate the behavior of two bonding systems: self-etching primer Clearfil Liner Bond 2V (CLB) and total-etch Single Bond (SB) when submitted to two bond strength tests: shear bond strength (SBS) and microtensile (MTBS). METHODS: Flat dentin surfaces were obtained at the facial surface of extracted bovine incisors. muTBS started with adhesive application and incremental resin composite insertion. Samples were then sliced into 1 mm slabs parallel to the long axis of the tooth. Half of the specimens from each group were trimmed in order to obtain dumbbell-shaped (D) specimens with a cross-sectional area of 1 mm2, and in the other half of the group, the slabs were cut into beams (B) with a cross section of 1 mm2 area. Specimens were individually fractured on a microtensile apparatus. For SBS, crown segments were embedded in polyester resin and a flat dentin surface was exposed for bonding. After adhesive and restorative procedures were accomplished, the specimens were kept in water for 24 hours prior to bond testing. The tests were performed in a universal testing machine. MPa values were analyzed by Tukey's test (P < 0.05), two-way ANOVA (muTBS) and Student's t-test (SBS). RESULTS: Mean values (SD) on muTBS were: SB/B: 42.6 (15.1), SB/D: 35.4 (6.8), CLB/B: 14.3 (10.3) and CLB/D: 27.0 (7.9). SBS values (SD) were: SB: 17.3 (5.6) and CLB 15.9 (7.2). Beam specimens bonded with CLB presented the lowest results. SBS did not show statistical differences between groups. The results showed that the shear bond test seemed to lack the sensitivity that is required to detect subtle differences between bonding agents or procedures.

Animals↗

PubMed2006

Microtensile bond strengths of composite to dentin treated with desensitizer products.

PURPOSE: This study was designed to analyze the influence of desensitizing procedures on dentin bond strength. MATERIALS AND METHODS: Forty bovine incisors were used, divided into four groups (n = 10): G1: control; G2: Gluma Desensitizer (Heraeus Kulzer); G3: Oxa-Gel (Art-Dent); G4: low-intensity laser (MMOptics). The buccal surface was wet ground flat with 180-, 400- and 600-grit silicon carbide abrasive paper to expose midcoronal dentin and create a uniform surface. After the application of the desensitizing agents to the exposed dentin, the specimens were etched with 35% phosphoric acid for 30 s, and an adhesive (Single Bond) was applied and light cured. A 4-mm high crown of composite resin (Filtek Z250) was then built up. Specimens were trimmed to an hourglass shape with cross sections of 1 mm2. Each specimen was individually fractured by a microtensile testing machine at a crosshead speed of 0.5 mm/min. The data, recorded in MPa, were analyzed with one-way ANOVA and the Duncan test (p = 0.05). RESULTS: Specimens treated with dentin desensitizers (except Gluma) yielded significantly lower mean bond strengths than nontreated control specimens. The mean values in MPa (+/- SD) were: G1: 13.4 (6.2); G2: 13.2 (4.8); G3: 7.15 (4.3); G4: 7.21 (4.6). CONCLUSIONS: Among the desensitizing agents studied, only Gluma Desensitizer did not detrimentally influence the bond strength values. It is a useful material for dentin desensitization.

Acid Etching, Dental↗

PubMed2005

Microleakage study of three adhesive systems.

The purpose of this in vitro study was to evaluate the efficacy of three hydrophilic dentin adhesive systems to reduce class II restoration microleakage. A total of 60 human molar teeth were used in which two box cavities were made on the distal and mesial surfaces, with a cervical margin in dentin. These cavities were randomly divided into 3 groups (n = 40 each), according to adhesive system tested: G1: OptiBond SOLO; G2: Amalgambond Plus; G3: Etch & Prime 3.0. The cavities were restored with the composite resin Z-100. The groups were thermocycled 2000 times (5 +/- 1 degrees C and 55 +/- 1 degrees C) with a dwell time of 1 min. The teeth were then immersed in 2% methylene blue, pH 7.0, for 4 h, sectioned and observed with a stereomicroscope MEIJI 2000 (35X). The evaluation was made using scores (0-4) and the results were expressed through the sum of the ranks. G1 = 1994.00; G2 = 2294.00; G3 = 2972.00. The three groups were significantly different. The self-etching adhesive system Etch & Prime 3.0 was less effective in preventing microleakage. The OptiBond SOLO adhesive was the most effective in reducing microleakage in dentin margins when compared with Amalgambond Plus and Etch & Prime 3.0.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2005

Shear bond strength evaluation of composite resin on enamel and dentin after nonvital bleaching.

BACKGROUND: Studies have shown that bleaching agents interfere with the adhesion of composite resin placed immediately after bleaching. PURPOSE: The aim of this study was to evaluate the shear bond strengths of composite resin after four different durations since the time of nonvital bleaching (1 d and 1, 2, and 3 wk). MATERIALS AND METHODS: Two hundred seventy bovine teeth were assigned to nine groups (n = 30) according to the bleach used and the time between bleaching and restoration: group 1--sodium perborate (SP), 1 day after bleaching (AB); group 2--SP, 1 week AB; group 3--SP, 2 weeks AB; group 4--SP, 3 weeks AB; group 5--37% carbamide peroxide (CP), 1 day AB; group 6--CP, 1 week AB; group 7--CP, 2 weeks AB; group 8--CP, 3 weeks AB; group 9--control group (no treatment). After the bleaching treatment, the teeth in each group were sectioned and the enamel and dentin were separated. The teeth were cut, embedded in polyester resin, and polished to obtain flat enamel and dentin surfaces. The adhesive system was applied and a cylinder of composite resin was bonded on each flat surface. The specimens were stored in distilled water for 7 days at 37 degrees C. The shear bond strength test was performed in a universal test machine (Emic DL-500, São José dos Pinhais, São Paulo, Brazil) at a crosshead speed of 0.5 mm/min. RESULTS: The data were subjected to analysis of variance, Dunnett's t-test, and Tukey's least significant difference at p < or = .05 and showed a statistically significant decrease in bond strengths of composite resin for enamel and dentin 1 day after the nonvital bleaching. CLINICAL SIGNIFICANCE: The decrease in shear bond strength values is time dependent. A delay in bonding procedures for composite resin restoration is recommended. According to the results, a satisfactory time to perform the restoration of composite resin for both enamel and dentin is 2 weeks after bleaching.

Analysis of Variance↗

PubMed2004

Shear bond strength after dentin bleaching with 10% carbamide peroxide agents.

This in vitro study evaluated the shear bond strength (SBS) of dentin treated with two 10% carbamide peroxide bleaching agents 15 days after bleaching and storage in artificial saliva. Dentin fragments were randomly divided into 3 groups (n = 20) for the treatment with the two different bleaching agents (Rembrandt 10% or Opalescence 10%) or with a placebo agent, applied to the tooth surface for 8 hours a day. During the remaining time, the specimens were stored in artificial saliva. After 42 days, the fragments were stored in artificial saliva for 14 days. Another group (n = 20) was exposed to distilled and deionized water for 56 days. An adhesive system and microhybrid composite resin were used to prepare specimens for the SBS test. SBS tests were performed and the fractured surfaces were visually examined using a stereoscope at 30 x magnification. The analysis of variance (ANOVA) and SIDAK tests showed higher SBS values for dentin treated with Opalescence 10% than for dentin treated with Rembrandt 10% or placebo. Groups treated with Rembrandt 10%, Opalescence 10% or placebo did not differ from the group treated with distilled and deionized water. Ten percent carbamide peroxide agents or a placebo agent caused no differences in SBS of dentin after 15 days of storage in artificial saliva.

Analysis of Variance↗

PubMed2004

Shear bond strength of enamel treated with seven carbamide peroxide bleaching agents.

PURPOSE: Lower average values of bond strength of adhesive systems to enamel bleached with 10% carbamide peroxide agents have been reported, but the effects of higher concentrations of carbamide peroxide bleaching agents are still unknown. The aim of this in vitro study was to evaluate the shear bond strength of enamel treated with different concentrations of carbamide peroxide to an adhesive system after a postbleaching period of storage in artificial saliva for 15 days. MATERIALS AND METHODS: Seven carbamide peroxide bleaching agents with concentrations varying from 10 to 22% were analyzed. A placebo agent was used as a control group. The agents were applied on the enamel fragments for 8 h/d for 42 days. During the remaining time, the specimens were stored in artificial saliva. After that time, the fragments were stored individually in artificial saliva for 15 days. An adhesive system was used to bond resin-based composite cylinders on the enamel surface. Shear bond strength tests were performed and the fractured surfaces of the specimens were visually examined with a stereomicroscope at x 30. RESULTS: The analysis of variance did not show differences in shear bond strength among the treatment agents. The fractures for all treatment agents were predominantly adhesive. CONCLUSION: After 15 days storage in artificial saliva, different concentrations of carbamide peroxide bleaching agents and a placebo agent had the same enamel shear bond strength values. CLINICAL SIGNIFICANCE: Concentrations varying from 10 to 22% carbamide peroxide agents cause no differences in shear bond strength of enamel to an adhesive system after 15 days of storage in artificial saliva.

Analysis of Variance↗

PubMed2004

Influence of phosphoric acid pretreatment on self-etching bond strengths.

PURPOSE: The purpose of this investigation was to evaluate the influence of phosphoric acid pretreatment on shear bond strength of two self-etching bonding systems to enamel and dentin. MATERIALS AND METHODS: Forty-eight extracted third human molar teeth were mounted, embedded into polystyrene resin, polished with 600-grit aluminum oxide papers, and randomly divided into four groups (n = 12): group 1-Clearfil Liner Bond 2V (Kuraray Co. Ltd., Osaka, Japan); group 2-One Up Bond F (Tokuyama Corp., Tokyo, Japan); group 3-phosphoric acid (Condicionador Dental Gel, Dentsply Ind. Com. LTDA, Rio de Janeiro, Brazil) and Clearfil Liner Bond 2V; group 4-phosphoric acid and One Up Bond F. In groups 3 and 4 the substrate was pre-etched for 15 seconds with 37% phosphoric acid, rinsed, and dried with an air stream. In all groups adhesive systems were applied according to manufacturers' instructions and light cured; then a restorative composite resin (TPH Spectrum, Dentsply Ind. Com. LTDA) was placed in a polytef matrix and cured. The specimens were stored in humidity for 7 days at 37 degrees C. The shear bond strength test was performed in a universal test machine with a crosshead speed of 0.5 mm/min. All procedures were repeated for the dentin evaluation. Mean values were analyzed with two-way analysis of variance and Duncan tests (p < .05). RESULTS: The values obtained are listed in decreasing order: enamel-group 3 = 24.6 MPa, group 4 = 23.6 MPa, group 1 = 19.2 MPa, group 2 = 8.5 MPa; dentin-group 1 = 17.2 MPa, group 2 = 16.1 MPa, group 4 = 13.1 MPa, group 3 = 11.3 MPa. CONCLUSIONS: Under the conditions of this study, enamel etching with 37% phosphoric acid provided statistically significant higher shear bond strength values, regardless of the adhesive system. However, in dentin, for Clearfil Liner Bond 2V, phosphoric acid pretreatment negatively affected bond strength values. CLINICAL SIGNIFICANCE: The use of self-etching systems in composite-to-enamel bonding restorative techniques still needs improvement when compared with the high bond strengths obtained with phosphoric acid treatment. However, lower shear bond strengths were observed in dentin when phosphoric acid was used in association with either adhesive system.

Acid Etching, Dental↗

PubMed2004

Effect of two different restorative techniques using resin-based composites on microleakage.

PURPOSE: To evaluate in vitro the extent of microleakage of Class II cavities restored with two different brands of resin-based composite, one hybrid (Tetric Ceram) and the other "packable" (Surefil) taking into account two variables: the localization of the margins and the insertion technique. METHODS: 100 bovine teeth, recently extracted, had standardized Class II slot cavities prepared on the mesial and distal surfaces with the gingival floor located on enamel or dentin, for a total 200 cavities. The teeth were randomly divided into eight groups of 25 teeth each (25 restorations in each group): (1) margin on dentin, restored with Surefil, bulk insertion; (2) margin on dentin, restored with Tetric Ceram, bulk insertion; (3) Margin on enamel, restored with Surefil, incremental technique; (4) margin on enamel, restored with Tetric Ceram, incremental technique; (5) margin on enamel, restored with Surefil, bulk insertion; (6) margin on enamel, restored with Tetric Ceram, bulk insertion; (7) margin on dentin, restored with Surefil, incremental technique; (8) margin on dentin, restored with Tetric Ceram, incremental technique. After this procedure, the teeth were subjected to 1000 thermocycles, stained with 2% methylene blue solution, and then sectioned in the mesiodistal direction. Dye penetration at tooth/restoration interface was scored based upon the extent of the dye using a light stereoscope x 35. RESULTS: All groups showed considerable levels of microleakage at both dentin and enamel margins (P < 0.05). Restorations with margins in enamel using the hybrid resin-based composite with the incremental technique did not show statistically significant differences when compared to bulk placement. However, restorations with hybrid resin-based composite have significantly less microleakage than either bulk or incremental technique for the "packable" resin-based composite Surefil. As for the margins in dentin, Tetric Ceram in bulk placement did not differ from the incremental technique and Tetric in bulk placement had significantly less microleakage than Surefil either bulk or incremental technique. The hybrid resin-based composite with margins in dentin and incremental technique showed less microleakage than the "packable" resin in bulk placement. CLINICAL SIGNIFICANCE: The two types of resin-based composites, hybrid and "packable" were unable to completely prevent microleakage. The study demonstrated the difficulty in sealing a proximal margin.

Animals↗

PubMed2004

The effect of sodium hypochlorite on microleakage of composite resin restorations using three adhesive systems.

PURPOSE: The aim of this study was to evaluate the effect of three different adhesive systems on microleakage of Class V restorations after the use of sodium hypochlorite. MATERIALS AND METHODS: One-hundred eighty bovine incisors were selected and randomly divided into 9 groups (n = 20): G1: Single Bond (SB); G2: 10% NaOCl solution (NS) + SB; G3: 10% NaOCl gel (NG) + SB; G4: Prime & Bond NT (PB); G5: NS + PB; G6: NG + PB; G7: Gluma One Bond (GOB); G8: NS + GOB; G9: NG + GOB. Standardized Class V cavities were prepared. All teeth were etched with 37% phosphoric acid for 15 s. In groups 2, 5, and 8, a 10% NaOCl solution was applied for 60 s to the dentin, and in groups 3, 6, and 9, a 10% NaOCl gel was applied to dentin for 60 s. All cavities were restored with composite resin Definite. The specimens were thermocycled for 1000 cycles (5 degrees C to 55 degrees C) and then immersed in 2% buffered solution of methylene blue for 4 h. The specimens were sectioned and analyzed according to a ranking score (0 to 4). Kruskal-Wallis and Mann-Whitney non-parametric tests (p < or = 0.05) were used for statistical analysis. RESULTS: The NaOCl treatment significantly increased microleakage at the dentin margin (p = 0.0129) as shown by the following sums of ranks: G1 = 1008.0a; G4 = 1301.5ab; G3 = 1687.0ab; G7 = 1744.0bc; G2 = 1802.0c; G9 = 1880.0c; G5 = 1889.0c; G8 = 1950.0c; G6 = 1963.0c (different superscripts indicate significant differences). For enamel, there were no statistically significant differences among the groups (p > 0.05). CONCLUSION: Depending on the adhesive system used, the application of NaOCl increased microleakage along dentin margins.

Acid Etching, Dental↗

PubMed2004

Microleakage and gap formation of resin composite restorations polymerized with different techniques.

PURPOSE: To evaluate the effect of different polymerization techniques on microleakage and gap formation of resin-based composite restorations. One correlation test was also carried out between these methodologies. METHODS: 180 vertical slot cavities were prepared in bovine teeth and filled with Z250/Single Bond system, for the following six groups (n=30): Soft-start I - 10 seconds at 75 mW/cm2 + 30 seconds at 560 mW/cm2; Soft-start II - 10 seconds at 190 mW/cm2 + 30 seconds at 560 mW/cm2; Pulse delay - 3 seconds at 300 mW/cm2 + 5 minutes waiting + 30 seconds at 560 mW/cm2; Plasma arc - 3 seconds at 1,500 mW/cm2; High intensity - 40 seconds at 810 mW/cm2; Conventional (control) - 40 seconds at 560 mW/cm2. After polishing, epoxy replicas were prepared for electron microscopy analysis (n=10), at x500 magnification. The samples were thermocycled, new epoxy replicas were prepared, and the teeth were immersed in 2% methylene blue dye solution for 4 hours. Marginal gaps were evaluated again and the microleakage was assessed. RESULTS: No statistical difference among polymerization techniques was observed for microleakage (Kruskal-Wallis test). For gap formation there was no statistical difference among polymerization techniques either before or after thermocycling (Tukey test). Conversely, thermocycling significantly increased the gap formation for all groups. No correlation (Spearman correlation test) was observed for the results of microleakage and gap formation.

Animals↗

PubMed2004

In vitro study of fracture resistance of bovine roots using different intraradicular post systems.

OBJECTIVES: This study evaluated, in vitro, the fracture resistance of bovine roots restored with five different intraradicular post systems. METHOD AND MATERIALS: Seventy-five bovine roots of similar dimensions were assigned to five groups (n = 15), according to the intraradicular post system used: cast post and core; titanium post; carbon-fiber post; glass-fiber post; and zirconium-oxide post. Following post cementation, the roots were embedded in polystyrene resin composite and submitted to fracture-resistance testing, with a compressive load at an angle of 135 degrees in relation to the long axis of the root at a speed of 0.5 mm/min. All data were statistically analyzed with analysis of variance and Sidak test. RESULTS: The titanium posts presented higher mean values of fracture resistance when compared to glass-fiber posts and zirconium-oxide posts and similar values compared to carbon-fiber posts. Also, roots treated with cast posts and cores presented similar results when compared to roots treated with prefabricated posts. CONCLUSION: All prefabricated intraradicular post systems evaluated presented similar resistance to fracture when compared to cast posts and cores, and among the prefabricated ones, titanium and carbon-fiber posts could be best indicated.

Analysis of Variance↗

PubMed2004

The effect of nonvital bleaching on the shear bond strength of composite resin using three adhesive systems.

PURPOSE: To evaluate the effect of nonvital bleaching on the shear bond strength of composite resin using three adhesive systems. MATERIALS AND METHODS: Two hundred seventy bovine teeth were assigned to 3 groups (n = 90): SP, paste of sodium perborate and water; CP, 37% carbamide peroxide; CO, control group (no treatment). After the bleaching treatment, the teeth in each group were cut into enamel (E) and dentin (D) sections. The teeth were embedded in polyester resin and polished in order to obtain a flat E or D surface. Each group was divided into 6 subgroups (n = 15) according to substrate (E and D) and adhesive system: SB, Single Bond (solvent: water/alcohol); PB, Prime & Bond NT (solvent: acetone); CLF, Clearfil SE Bond (solvent: water). The adhesive system was applied on each flat surface according to the manufacturer's instructions and a cylinder of composite resin Z-250 was overlaid. The specimens were stored in distilled water for 7 days at 37 degrees C. The SBS test was performed in a universal testing machine with crosshead speed of 0.5 mm/min. The data obtained (in MPa) were statistically analyzed with two-way ANOVA and Tukey's test (p < or = 0.05). RESULTS: The bleaching treatment influenced the SBS, regardless of the adhesive system used. On enamel, the SP and CP bleaching treatments reduced the SBS values. On dentin, the SP bleaching agent reduced the SBS values, but the CP bleaching did not. CONCLUSION: Nonvital bleaching treatment with sodium perborate may adversely affect shear bond strength of composite resin for both enamel and dentin. Similar effects can be expected from 37% carbamide peroxide bleaching agent on enamel but not dentin bonding strength. The use of water/alcohol and acetone-based adhesive systems cannot reverse the effects of bleaching treatments on bond strengths.

Analysis of Variance↗

PubMed2003

Effects of bleaching with carbamide peroxide gels on microhardness of restoration materials.

The objective of this in vitro study was to quantitatively assess the effects of bleaching with 10 and 15% carbamide peroxide (CP) on restoration materials by performing superficial microhardness analysis. Acrylic cylindrical containers (4 x 2 mm) were filled with the following restoration products: Charisma (Heraues Kulzer, Vila Santa Catarina, São Paulo, Brazil), Durafill VS (Heraeus Kulzer), Vitremer (3M, Sumaré, São Paulo, Brazil), Dyract (Dentsply, Petrópolis, Rio de Janeiro, Brazil), and Permite C (SDI, São Paulo, São Paulo, Brazil). Sixty samples were prepared of each restoration material. Twenty samples received bleaching treatment with 10% CP, 20 samples received bleaching treatment with 15% CP, and 20 samples were kept submerged in artificial saliva, which was replaced daily. The treatment consisted of immersion of the specimens in 1 cm3 of CP at 10 and 15% for 6 hours per day during 3 weeks, whereupon the test specimens were washed, dried, and kept immersed in artificial saliva for 18 hours. Then the test and control specimens were analyzed using a microhardness gauge. The Knoop Hardness Number (KHN) was taken for each test and control specimen at five different locations by applying a 25 g force for 20 seconds. The values obtained were transformed into KHNs and the mean was calculated. The data were submitted to statistical analysis by analysis of variance and Tukey test, p < .05. The means/standard deviations were as follows: Charisma: CP 10% 38.52/4.08, CP 15% 34.31/6.13, saliva 37.36/4.48; Durafill VS: CP 10% 18.65/1.65, CP 15% 19.38/2.23, saliva 18.27/1.43; Dyract AP: CP 10% 30.26/2.81, CP 15% 28.64/5.44, saliva 33.88/3.46; Vitremer: CP 10% 28.15/3.04, CP 15% 17.40/3.11, saliva 40.93/4.18; and Permite C: CP 10% 183.50/27.09, CP 15% 159.45/5.78, saliva 215.80/26.15. A decrease in microhardness was observed for the materials Dyract AP, Vitremer, and Permite C after treatment with CP at 10 and 15%, whereas no effect on either of the two composites (Charisma and Durafill) was verified. CLINICAL SIGNIFICANCE The application of the carbamide peroxide gels at 10 and 15% did not alter the microhardness of the composite resins Charisma and Durafill. In situ and clinical studies are necessary to enable one to conclude that the reduction in microhardness of the materials effectively results in clinical harm to the restorations.

Analysis of Variance↗

PubMed2003

Six-month storage-time evaluation of one-bottle adhesive systems to dentin.

PURPOSE: The goal of this study was to evaluate the 1-week, 3-month, and 6-month performance of eight commercially available one-bottle adhesive systems to dentin. MATERIALS AND METHODS: Lingual and buccal surfaces from human third molars were ground wet on 600-grit SiC paper to obtain a flat dentinal surface. The specimens were randomly divided into 24 groups (n = 10), which were established to measure the shear bond strengths of Bond-1 (B1), ONE-STEP (OS), OptiBond SOLO (OP), Prime & Bond 2.1 (PB), Single Bond (SB), STAE (ST), Syntac Sprint (SS), and Tenure Quick (TQ) after 1-week, 3-month, and 6-month water storage at 37 degrees C. One-bottle adhesives were applied according to manufacturers' instructions and Z100 composite cylinders were applied on the bonded dentinal surfaces. The 3-month water-storage groups were thermocycled for 1500 cycles at 5 degrees C and 55 degrees C and 6-month groups for 3000 cycles. After storage periods, specimens were tested in shear in a universal testing machine (0.5 mm/min). RESULTS: were statistically analyzed by analysis of variance and Tukey test. Results: The changes in shear bond strengths were not uniform over time. Over the test period, OS, PB, SB, and SS exhibited bond strength stability, however, SS presented low bond strengths on all tested periods. A significant decrease in bond strength was observed for B1, OP, ST, and TQ after the 6-month storage period.

Analysis of Variance↗

PubMed2003

Influence of load cycling on marginal microleakage with two self-etching and two one-bottle dentin adhesive systems in dentin.

PURPOSE: To evaluate the influence of occlusal load cycling on cervical microleakage of proximal slot restorations located in dentin, using two self-etching and two one-bottle dentin adhesive systems. MATERIALS AND METHODS: 240 proximal slot cavities were prepared in 120 bovine teeth and divided into two groups, one with load cycling and one without. The groups were then subdivided into four subgroups according to the adhesive system used (Experimental EXL 547 Self-etching 3M, Clearfil SE Bond, Single Bond, and Optibond Solo Plus) and restored following the manufacturers' instructions. The teeth were then submitted to mechanical load cycling with a force of 80 N and a frequency of 5 Hz, simultaneously over both restorations of each tooth, for a total of 50,000 cycles per specimen. All specimens were subsequently immersed in a 2% methylene blue solution (pH 7.0), and sectioned to examine the extent of dye penetration under a stereomicroscope (40X). RESULTS: There was no statistically significant difference (p = 0.00002) between the loaded and unloaded teeth. However, a statistically significant difference was observed between the adhesive systems used. The experimental self-etching EXL 547 presented the lowest mean microleakage, but was only statistically significantly different from the Single Bond loaded and unloaded groups and the Clearfil SE Bond unloaded group. CONCLUSION: The application of 50,000 loading cycles did not affect the microleakage of the two self-etching and the two one-bottle adhesive systems evaluated. In vitro mechanical load cycling is an important factor to consider when evaluating the performance of adhesive systems under simulated masticatory conditions.

Animals↗

PubMed2002

[Effect of techniques of composite resin insertion and polymerization on microleakage and microhardness].

The aim of this study was to evaluate the influence of techniques of composite resin polymerization and insertion on microleakage and microhardness. One hundred and eighty class II cavities were prepared in bovine teeth and assigned to six groups: G1 - bulk filling + conventional polymerization; G2 - bucco-lingual increments + conventional polymerization; G3 - bulk filling + soft-start polymerization; G4 - bucco-lingual increments + soft-start polymerization; G5 - bulk filling + progressive polymerization; G6 - bucco-lingual increments + progressive polymerization. All cavities were restored with the Z100/Single Bond system (3M). After thermocycling, the samples were immersed in 2% methylene blue dye solution for 4 hours. Half of the samples were embedded in polystyrene resin, and Knoop microhardness was measured. The Kruskal-Wallis test did not reveal statistical differences (p > 0.05) between the polymerization and insertion techniques as to microleakage. Regarding microhardness, the two-way ANOVA and the Tukey test did not reveal statistical differences between the restorative techniques (p > 0.05), but progressive polymerization (G5 and G6) was associated with smaller Knoop microhardness values (p < 0.05): G = 144.11; G2 = 143.89; G3 = 141.14; G4 = 142.79; G5 = 132.15; G6 = 131.67. It was concluded that the evaluated polymerization and insertion techniques did not affect marginal microleakage, but a decrease in microhardness occurred when progressive polymerization was carried out.

Acrylic Resins↗

PubMed2002

Evaluation of microleakage in cervical margins of various posterior restorative systems.

PURPOSE: The purpose of this in vitro study was to evaluate the microleakage and dye penetration patterns of various restorative systems in the cervical margins of Class II cavities using the dye penetration technique. MATERIALS AND METHODS: Ninety bovine incisors were selected and part of the crown was sectioned producing a standardized occlusogingival margin of 4 mm. Standardized Class II box cavities were designed on the mesial (MO) and distal (OD) surfaces with the gingival margin in dentin. The cavities were randomly divided into six groups (n = 30): group 1 (control), Etch & Prime 3.0 (Degussa AG) + Definite (Degussa AG); group 2, Prime & Bond NT (Dentsply De Trey) + Definite; group 3, Etch & Prime 3.0 + flowable composite resin Wave (SDI) + Definite; group 4 (control), Prime & Bond NT + TPH Spectrum (Denstply De Trey); group 5, Etch & Prime 3.0 + TPH Spectrum; group 6, Prime & Bond NT + Wave + TPH Spectrum. After they were finished and polished, the specimens were subjected to 1500 thermal cycles in baths of 5 degrees+/-2 degrees C and 55 degrees+/-2 degrees C with 60 seconds of dwell time for each bath. After the thermocycling, the specimens were sealed with acid-resistant varnish, leaving a 1-mm window around the cervical margin interface, and immersed in 2% methylene blue buffered solution for 4 hours. Then the specimens were sectioned longitudinally in half and qualitatively evaluated under stereomicroscopy at 45 times magnification, using ranked scores for the dentin cervical margin (0-4). The dye penetration pattern (adhesive or dentinal) was also evaluated. The data were subjected to a reproducibility kappa test, and the mean of the three examiners' scores was analyzed by the Kruskal-Wallis nonparametric test and a multiple comparison nonparametric test. Fisher's exact test was used to evaluate the dye penetration pattern. RESULTS: The rank sums of the groups were expressed in decreasing order: group 4, 67.23a; group 3, 72.58ab; group 6, 78.43ab; group 5, 93.19bc; group 2, 112.97c; group 1, 113.52c. (Statistically significant differences are expressed by different superscript letters.) The results indicate that none of the systems used in this study was able to impede microleakage, and that the use of a flowable resin decreases the values of leakage only for Definite composite resin. The dye penetration pattern for the groups that used Prime & Bond NT was predominantly dentinal, whereas the pattern for Etch & Prime 3.0 groups was adhesive. CLINICAL SIGNIFICANCE: An ormocer-based resin that was developed to improve the physical properties of composite resin and a self-etching primer adhesive system obtained higher values of microleakage compared with a one-bottle adhesive system and a microhybrid composite resin. The flowable composite resin decreased the values of microleakage only for the ormocer-based resin.

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