637 research outputs found

    Editorial

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    Impact of adhesive application errors on dentin bond strength of resin composite.

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    Objectives: To investigate the impact of adhesive application errors on dentin bond strength of resin composite. Material and Methods: 165 extracted permanent human molars were ground to mid-coronal dentin. The dentin specimens were treated with one of three adhesive systems (OptiBond FL, Clearfil SE, Scotchbond Universal) either according to manufacturer's instructions or with systematic errors in the application procedure and before application of resin composite (Filtek Z250). After storage (37 °C, 100% humidity, 24 h) shear bond strength (SBS) was measured and data analysed with either one-way ANOVA followed by Tukey tests (OptiBond FL, Scotchbond Universal, control groups) or Kruskal-Wallis followed by Wilcoxon tests (Clearfil SE). Finally, the failure mode of all specimens was assessed. Results: With OptiBond FL and Clearfil SE omitted application (p ≤ 0.0001) as well as no evaporation (p ≤ 0.001) of the solvents in the primer significantly reduced the SBS. Omitted application of the adhesive, respectively the bond, had a negative influence on the SBS of Clearfil SE (p < 0.0001), but not of OptiBond FL (p = 0.776). With Scotchbond Universal, no evaporation of the solvents (p < 0.0001) as well as no light-cure (p = 0.0004) had a significant negative influence on the SBS. Using the adhesive systems according to manufacturer's instructions, Clearfil SE achieved significantly lower SBS than OptiBond FL and Scotchbond Universal (p = 0.0027). Adhesive failure at the dentin surface was generally the most frequent failure mode observed. Conclusion: All three adhesive systems tested were sensitive to application errors. For optimal result and longest possible durability of resin restorations, clinicians should strictly adhere to the manufacturer's instructions

    Micromorphology and adhesive performance of Er:YAG laser-treated dentin of primary teeth

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    This study evaluated (1) the micromorphology by scanning electron microscopy (SEM) and (2) the adhesive performance by microtensile bond strength (μTBS) of diamond bur-treated dentin compared to Er:YAG laser-treated dentin of human primary teeth. (1) For qualitative SEM evaluation, dentin of 18second primary molars (n = 3/method) was treated with either diamond bur as a control (group 1a: 40μm diamond bur only (clinical situation); group 1b: grinding + 40μm diamond bur) or with Er:YAG laser (group 2a (clinical situation, manufacturer's settings): 200mJ/25Hz (5W) + 100mJ/35Hz (3.5W) laser only; group 2b (experimental setting "high"): grinding + 400mJ/20Hz (8W); group 2c (manufacturer's setting "finishing"): grinding + 100mJ/35Hz (3.5W); group 2d (experimental setting "low"): grinding + 50mJ/35Hz (1.75W)). (2) For evaluation of adhesive performance, 64second primary molars were divided into four groups and treated as described for group 1b and groups 2b/c/d (n = 16/method), and μTBS of Clearfil SE/Clearfil Majesty Esthetic to dentin was measured. The SEM micrographs were qualitatively analyzed. The μTBS values were compared with a Kruskal-Wallis test. The significance level was set at α = 0.05. SEM micrographs showed the typical micromorphologies with a smear layer for the diamond bur groups and open dentin tubules for all laser-treated groups. However, in group 2d, the laser beam had insufficiently irradiated the dentin area, rendering the underlying ground surface partly visible. There were no statistically significant differences between μTBS values of the four groups (p = 0.394). This suggests that Er:YAG laser treatment of dentin of primary molars provides bond strengths similar to those obtained following diamond bur treatmen

    The effect of a tin-containing fluoride mouth rinse on the bond between resin composite and erosively demineralised dentin

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    Objectives: To evaluate the effect of a tin-containing fluoride (Sn/F) mouth rinse on microtensile bond strength (μTBS) between resin composite and erosively demineralised dentin. Materials and methods: Dentin of 120 human molars was erosively demineralised using a 10-day cyclic de- and remineralisation model. For 40 molars, the model comprised erosive demineralisation only; for another 40, the model included treatment with a NaF solution; and for yet another 40, the model included treatment with a Sn/F mouth rinse. In half of these molars (n = 20), the demineralised organic matrix was continuously removed by collagenase. Silicon carbide paper-ground, non-erosively demineralised molars served as control (n = 20). Subsequently, μTBS of Clearfil SE/Filtek Z250 to the dentin was measured, and failure mode was determined. Additionally, surfaces were evaluated using SEM and EDX. Results: Compared to the non-erosively demineralised control, erosive demineralisation resulted in significantly lower μTBS regardless of the removal of demineralised organic matrix. Treatment with NaF increased μTBS, but the level of μTBS obtained by the non-erosively demineralised control was only reached when the demineralised organic matrix had been removed. The Sn/F mouth rinse together with removal of demineralised organic matrix led to significantly higher µTBS than did the non-erosively demineralised control. The Sn/F mouth rinse yielded higher μTBS than did the NaF solution. Conclusions: Treatment of erosively demineralised dentin with a NaF solution or a Sn/F mouth rinse increased the bond strength of resin composite. Clinical relevance: Bond strength of resin composite to eroded dentin was not negatively influenced by treatment with a tin-containing fluoride mouth rins

    Class I Gap-formation in Highly-viscous Glass-ionomer Restorations: Delayed vs Immediate Polishing

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    This in vitro study evaluated the effects of delayed versus immediate polishing to permit maturation of interfacial gap-formation around highly viscous conventional glass-ionomer cement (HV-GIC) in Class I restorations, together with determining the associated mechanical properties. Cavity preparations were made on the occlusal surfaces of premolars. Three HV-GICs (Fuji IX GP, GlasIonomer FX-II and Ketac Molar) and one conventional glass-ionomer cement (C-GIC, Fuji II, as a control) were studied, with specimen subgroups (n=10) for each property measured. After polishing, either immediately (six minutes) after setting or after 24 hours storage, the restored teeth were sectioned in a mesiodistal direction through the center of the model Class I restorations. The presence or absence of interfacial-gaps was measured at 1000× magnification at 14 points (each 0.5-mm apart) along the cavity restoration interface (n=10; total points measured per group = 140). Marginal gaps were similarly measured in Teflon molds as swelling data, together with shear-bond-strength to enamel and dentin, flexural strength and moduli. For three HV-GICs and one C-GIC, significant differences (p<0.05) in gap-incidence were observed between polishing immediately and after one-day storage. In the former case, 80–100 gaps were found. In the latter case, only 9–21 gaps were observed. For all materials, their shear-bond-strengths, flexural strength and moduli increased significantly after 24-hour storage.</p

    Class I Gap-formation in Highly-viscous Glass-ionomer Restorations: Delayed vs Immediate Polishing

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    This in vitro study evaluated the effects of delayed versus immediate polishing to permit maturation of interfacial gap-formation around highly viscous conventional glass-ionomer cement (HV-GIC) in Class I restorations, together with determining the associated mechanical properties. Cavity preparations were made on the occlusal surfaces of premolars. Three HV-GICs (Fuji IX GP, GlasIonomer FX-II and Ketac Molar) and one conventional glass-ionomer cement (C-GIC, Fuji II, as a control) were studied, with specimen subgroups (n=10) for each property measured. After polishing, either immediately (six minutes) after setting or after 24 hours storage, the restored teeth were sectioned in a mesiodistal direction through the center of the model Class I restorations. The presence or absence of interfacial-gaps was measured at 1000× magnification at 14 points (each 0.5-mm apart) along the cavity restoration interface (n=10; total points measured per group = 140). Marginal gaps were similarly measured in Teflon molds as swelling data, together with shear-bond-strength to enamel and dentin, flexural strength and moduli. For three HV-GICs and one C-GIC, significant differences (p<0.05) in gap-incidence were observed between polishing immediately and after one-day storage. In the former case, 80–100 gaps were found. In the latter case, only 9–21 gaps were observed. For all materials, their shear-bond-strengths, flexural strength and moduli increased significantly after 24-hour storage.</p

    Bond strength of additively manufactured composite resins to dentin and titanium when bonded with dual-polymerizing resin cements.

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    STATEMENT OF PROBLEM Additively manufactured composite resins for definitive restorations have been recently introduced. The bond strength between these composite resins and different substrates has not been extensively studied. PURPOSE The purpose of this in vitro study was to measure the shear bond strength (SBS) between additively manufactured composite resins and dentin and titanium substrates and compare those with the SBS between subtractively manufactured polymer-infiltrated ceramic and the same substrates (dentin and titanium), when different dual-polymerizing resin cements were used. MATERIAL AND METHODS One hundred and eighty cylinder-shaped specimens (Ø5×5 mm) were prepared from 3 materials recommended for definitive restorations: an additively manufactured composite resin (Crowntec [CT]); an additively manufactured hybrid composite resin (VarseoSmile Crown Plus [VS]); and a subtractively manufactured polymer-infiltrated ceramic (Enamic [EN]) (n=60). Specimens were randomly divided into six subgroups to be cemented to the two substrates (dentin and titanium; n=30) with 1 of 3 resin cements (RelyX Universal, Panavia V5, and Variolink Esthetic DC) (n=10). The restoration surface to be bonded was treated according to the respective manufacturer's recommendations. Dentin surfaces were treated according to the resin cement (Scotchbond Universal Plus Adhesive for RelyX Universal, Panavia V5 Tooth Primer for Panavia V5, and Adhese Universal for Variolink Esthetic DC), while titanium surfaces were airborne-particle abraded, and only the specimens paired with Panavia V5 were treated with a ceramic primer (Clearfil Ceramic Primer Plus). SBS was measured in a universal testing machine at a crosshead speed of 1 mm/min. Failure modes were analyzed under a microscope at ×12 magnification. Data were analyzed by using 2-way analysis of variance and Tukey honestly significant difference tests (α=.05). RESULTS When SBS to dentin was considered, only restorative material, as a main factor, had a significant effect (P<.001); EN had the highest SBS (P<.001), while the difference in SBS values of CT and VS was not significant (P=.145). As for SBS to titanium, the factors restorative material and resin cement and their interaction had a significant effect (P<.001). Within each resin cement, EN had the highest SBS to titanium (P<.001), and within each restorative material, Variolink resulted in the lowest SBS (P≤.010). Overall, EN and RelyX were associated with the highest SBS to titanium (P≤.013). Mixed failures were predominant in most groups. CONCLUSIONS Regardless of the substrate or the resin cement used, the subtractively manufactured polymer-infiltrated ceramic had higher shear bond strength than the additively manufactured composite resins. The SBS of the additively manufactured composite resins, whether bonded to dentin or titanium, were not significantly different from each other. Regardless of the restorative material, Variolink DC resulted in the lowest SBS for titanium surfaces

    Effect of tin-chloride pretreatment on bond strength of two adhesive systems to dentin

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    Objectives: To determine the effect on resin composite-to-dentin bond strength of incorporation of an acidic tin-chloride pretreatment in two adhesive systems. Materials and methods: Human molars were ground to expose mid-coronal dentin. For microtensile bond strength (μTBS) testing, dentin was treated with Optibond FL or Clearfil SE according to one of six protocols (n = 22/group). Group 1: Phosphoric acid etching, Optibond FL Prime, Optibond FL Adhesive (manufacturer's instructions; control); Group 2: Tin-chloride pretreatment, Optibond FL Prime, Optibond FL Adhesive; Group 3: Phosphoric acid etching, tin-chloride pretreatment, Optibond FL Prime, Optibond FL Adhesive; Group 4: Clearfil SE Primer, Clearfil SE Bond (manufacturer's instructions; control); Group 5: Phosphoric acid etching, Clearfil SE Primer, Clearfil SE Bond; and Group 6: Tin-chloride pretreatment, Clearfil SE Primer, Clearfil SE Bond. The molars were then built up with resin composite (Clearfil Majesty Esthetic). After storage (1week, 100% humidity, 37°C) the μTBS was measured and failure mode was determined. Additionally, pretreated dentin surfaces were evaluated using SEM and EDX. The μTBS results were analyzed statistically by a Welch Two Sample t-test and a Kruskal-Wallis test followed by exact Wilcoxon rank sum tests with Bonferroni-Holm adjustment for multiple testing (α = 0.05). Results: When Optibond FL was used, partial or total replacement of phosphoric acid with tin-chloride decreased μTBS significantly. In contrast, when Clearfil SE was used, inclusion of a tin-chloride pretreatment in the adhesive procedure increased μTBS significantly. Conclusions: Tin-chloride pretreatment had a beneficial influence on the bond promoting capacity of the MDP-containing adhesive system Clearfil SE
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