An integrative review on the toxicity of Bisphenol A (BPA) released from resin composites used in dentistry.

The main aim of this study was to perform an integrative review on the release of bisphenol A (BPA) from resin-matrix composites and potential toxic effects. A bibliographic search was performed on the PubMed platform using the following keywords: "Bisphenol A" OR "BPA" AND "resin composite" OR "composite resin" AND "toxicity" OR "cytotoxicity" OR "release". Inclusion criteria involved in vitro and in vivo studies on the release and toxicity of BPA. Results highlighted the release of BPA from resin-matrix composites due to insufficient polymerization and/or degradation of the polymeric matrix. BPA is part of the organic matrix of resin-matrix composites and may be hydrolysed in human saliva, although studies report that low doses might not be detected by traditional chemical analysis. Studies exposing zebrafish embryos to different concentrations of Bis-GMA, showed 55% mortality at 10 µM Bis-GMA while 30% mortality was recorded at 1 µM Bis-GMA. In patients, a BPA concentration of around 2.09 × 10-2  µg/ml was found in the saliva after placement of lingual orthodontic retainers with resin-matrix composites. Also, the BPA molecule can be swallowed and absorbed by the oral/gastrointestinal mucosa, which might result in systemic toxicity. The degradation of resin-matrix composites and release of BPA in oral environment are dependent on the organic matrix content and on the polymerization method. A increased release of BPA can lead to the absorption into oral and gastrointestinal mucosa with high risks of local and systemic toxicity.

A randomized, prospective clinical study evaluating effectiveness of a bulk-fill composite resin, a conventional composite resin and a reinforced glass ionomer in Class II cavities: one-year results.

OBJECTIVES: Bulk-fill restorative materials such as bulk-fill composite resins and high viscous glass ionomer cements have become very popular materials in operative dentistry because their application is easy and time-saving. The aim of this clinical study was to evaluate the clinical performance of a highly viscous reinforced glass ionomer material, a bulk-fill composite resin and a micro hybrid composite resin in Class II restorations. METHODOLOGY: In total, 109 Class II restorations were performed in 54 patients using three different restorative materials: Charisma Smart Composite (CSC); Filtek Bulk Fill Posterior Restorative (FBF); Equia Forte Fil (EF). Single Bond Universal adhesive (3M ESPE, Germany) was used with composite resin restorations. The restorations were evaluated using modified USPHS criteria in terms of retention, color match, marginal discoloration, anatomic form, contact point, marginal adaptation, secondary caries, postoperative sensitivity and surface texture. The data were analyzed using Chi-Square, Fischer's and McNemar's tests. RESULTS: At the end of one year, 103 restorations were followed up. No changes were observed during the first 6 months. At the end of one year, there were small changes in composite restorations (FBF and CSC) but no statistically significant difference was observed between the clinical performances of these materials for all criteria (p>0.05). However, there was a statistically significant difference between EF, FBF and CSC groups in all parameters except marginal discoloration, secondary caries and postoperative sensitivity in one-year evaluation (p<0.05). CONCLUSION: Bulk-fill composite resins and conventional composite resins showed more successful clinical performance than highly viscous reinforced glass ionomers in Class II cavities.

Bonding of universal adhesive system to enamel surrounding real-life carious cavities.

This study aimed to evaluate the bond strength of a universal adhesive system to enamel surrounding real-life carious cavities. Twenty-eight permanent molars (n = 7) with carious lesions in dentin were subjected to selective carious tissue removal to firm dentin and had their crowns sectioned longitudinally. A universal adhesive system (Single Bond Universal [SBU] used in either etch-and-rinse and self-etch strategies) was compared with an etch-and-rinse Adper Single Bond 2 (ASB) and a self-etch Clearfil SE Bond (CSE) adhesive systems (control systems). Adhesives were applied on the enamel, assumed demineralized, surrounding the cavity margins and on sound enamel (control substrate). Composite cylinders were built (0.72 mm2) and microshear bond strength (µSBS) test was performed after 24 h of water storage. The µSBS values (MPa) were analyzed using two-way ANOVA and Tukey's post hoc tests (α = 0.05). Bond strength values obtained in demineralized enamel surrounding carious cavity margins were significantly lower than that obtained in sound enamel (distant from carious cavity margins) (p = 0.035). The bonding strategy of the SBU did not influenced the bond strength values, which were higher than that obtained with ASB. CSE showed similar µSBS values to ASB and SBU in the self-etch mode. In conclusion, the bond strength to enamel assumed demineralized is lower than to sound enamel. The enamel surrounding carious cavities jeopardize the bonding of universal adhesive system. The bond strength of universal adhesive is similar, regardless to bonding strategy.

Twenty-four-month clinical performance of different universal adhesives in etch-and-rinse, selective etching and self-etch application modes in NCCL - a randomized controlled clinical trial.

OBJECTIVE: The aim of this randomized, controlled, prospective clinical trial was to evaluate the performances of two different universal adhesives and one etch-rinse adhesive for restoration of non-carious cervical lesions (NCCLs). MATERIAL AND METHODS: Twenty patients with at least seven NCCLs were enrolled. Lesions were divided into seven groups according to adhesive systems and application modes: GSE: GLUMA Universal-self-etch, GSL: GLUMA Universal-selective etching, GER: GLUMA Universal-etch-and-rinse, ASE: All-Bond Universal-self-etch, ASL: All-Bond Universal-selective etching, AER: All-Bond Universal-etch-and-rinse, SBE (Control): Single Bond2-etch-and-rinse. A total of 155 NCCLs were restored with a nano hybrid composite (Tetric N-Ceram). Restorations were scored with regard to retention, marginal discoloration, marginal adaptation, recurrent caries and post-operative sensitivity using modified United States Public Health Service (USPHS) criteria after one week, 6, 12 and 24 months. Statistical evaluations were performed using Chi-square tests (p=0.05). RESULTS: The recall rate was 81.9% after the 24-month follow-up. The cumulative retention rates for self-etch groups (GSE: 72.2%, ASE:75%) were significantly lower than other experimental groups (GSL: 93.7%, GER: 100%, ASL: 94.1%, AER: 100%, SBE: 100%) at the 24-month follow-up (p<0.05). Regarding marginal adaptation and marginal discoloration, GSE and ASE groups demonstrated more bravo scores after 6 and 12-month observations but differences were not significant (p>0.05). Only one restoration from ASL group demonstrated post-operative sensitivity at 6 and 12-month observations. No secondary caries was observed on the restorations at any recall. At the end of 24-month observations, no significant differences were detected among groups regarding any of the criteria assessed, except retention. CONCLUSION: GLUMA Universal and All-Bond Universal showed better results in etch-and-rinse and selective etching mode compared to the self-etch mode regarding retention. Etch-and-rinse and selective etching application modes of the current universal adhesives tended to provide better clinical outcomes considering the criteria evaluated at the end of 24-month evaluation.

Twenty-four-month clinical performance of different universal adhesives in etch-and-rinse, selective etching and self-etch application modes in NCCL - a randomized controlled clinical trial

Abstract Objective The aim of this randomized, controlled, prospective clinical trial was to evaluate the performances of two different universal adhesives and one etch-rinse adhesive for restoration of non-carious cervical lesions (NCCLs). Material and Methods Twenty patients with at least seven NCCLs were enrolled. Lesions were divided into seven groups according to adhesive systems and application modes: GSE: GLUMA Universal-self-etch, GSL: GLUMA Universal-selective etching, GER: GLUMA Universal-etch-and-rinse, ASE: All-Bond Universal-self-etch, ASL: All-Bond Universal-selective etching, AER: All-Bond Universal-etch-and-rinse, SBE (Control): Single Bond2-etch-and-rinse. A total of 155 NCCLs were restored with a nano hybrid composite (Tetric N-Ceram). Restorations were scored with regard to retention, marginal discoloration, marginal adaptation, recurrent caries and post-operative sensitivity using modified United States Public Health Service (USPHS) criteria after one week, 6, 12 and 24 months. Statistical evaluations were performed using Chi-square tests (p=0.05). Results The recall rate was 81.9% after the 24-month follow-up. The cumulative retention rates for self-etch groups (GSE: 72.2%, ASE:75%) were significantly lower than other experimental groups (GSL: 93.7%, GER: 100%, ASL: 94.1%, AER: 100%, SBE: 100%) at the 24-month follow-up (p<0.05). Regarding marginal adaptation and marginal discoloration, GSE and ASE groups demonstrated more bravo scores after 6 and 12-month observations but differences were not significant (p>0.05). Only one restoration from ASL group demonstrated post-operative sensitivity at 6 and 12-month observations. No secondary caries was observed on the restorations at any recall. At the end of 24-month observations, no significant differences were detected among groups regarding any of the criteria assessed, except retention. Conclusion GLUMA Universal and All-Bond Universal showed better results in etch-and-rinse and selective etching mode compared to the self-etch mode regarding retention. Etch-and-rinse and selective etching application modes of the current universal adhesives tended to provide better clinical outcomes considering the criteria evaluated at the end of 24-month evaluation.

Bonding of universal adhesive system to enamel surrounding real-life carious cavities

Abstract: This study aimed to evaluate the bond strength of a universal adhesive system to enamel surrounding real-life carious cavities. Twenty-eight permanent molars (n = 7) with carious lesions in dentin were subjected to selective carious tissue removal to firm dentin and had their crowns sectioned longitudinally. A universal adhesive system (Single Bond Universal [SBU] used in either etch-and-rinse and self-etch strategies) was compared with an etch-and-rinse Adper Single Bond 2 (ASB) and a self-etch Clearfil SE Bond (CSE) adhesive systems (control systems). Adhesives were applied on the enamel, assumed demineralized, surrounding the cavity margins and on sound enamel (control substrate). Composite cylinders were built (0.72 mm2) and microshear bond strength (µSBS) test was performed after 24 h of water storage. The µSBS values (MPa) were analyzed using two-way ANOVA and Tukey's post hoc tests (α = 0.05). Bond strength values obtained in demineralized enamel surrounding carious cavity margins were significantly lower than that obtained in sound enamel (distant from carious cavity margins) (p = 0.035). The bonding strategy of the SBU did not influenced the bond strength values, which were higher than that obtained with ASB. CSE showed similar µSBS values to ASB and SBU in the self-etch mode. In conclusion, the bond strength to enamel assumed demineralized is lower than to sound enamel. The enamel surrounding carious cavities jeopardize the bonding of universal adhesive system. The bond strength of universal adhesive is similar, regardless to bonding strategy.

A randomized, prospective clinical study evaluating effectiveness of a bulk-fill composite resin, a conventional composite resin and a reinforced glass ionomer in Class II cavities: one-year results

Abstract Bulk-fill restorative materials such as bulk-fill composite resins and high viscous glass ionomer cements have become very popular materials in operative dentistry because their application is easy and time-saving. Objectives: The aim of this clinical study was to evaluate the clinical performance of a highly viscous reinforced glass ionomer material, a bulk-fill composite resin and a micro hybrid composite resin in Class II restorations. Methodology: In total, 109 Class II restorations were performed in 54 patients using three different restorative materials: Charisma Smart Composite (CSC); Filtek Bulk Fill Posterior Restorative (FBF); Equia Forte Fil (EF). Single Bond Universal adhesive (3M ESPE, Germany) was used with composite resin restorations. The restorations were evaluated using modified USPHS criteria in terms of retention, color match, marginal discoloration, anatomic form, contact point, marginal adaptation, secondary caries, postoperative sensitivity and surface texture. The data were analyzed using Chi-Square, Fischer's and McNemar's tests. Results: At the end of one year, 103 restorations were followed up. No changes were observed during the first 6 months. At the end of one year, there were small changes in composite restorations (FBF and CSC) but no statistically significant difference was observed between the clinical performances of these materials for all criteria (p>0.05). However, there was a statistically significant difference between EF, FBF and CSC groups in all parameters except marginal discoloration, secondary caries and postoperative sensitivity in one-year evaluation (p<0.05). Conclusion: Bulk-fill composite resins and conventional composite resins showed more successful clinical performance than highly viscous reinforced glass ionomers in Class II cavities.

Silane coatings of metallic biomaterials for biomedical implants: A preliminary review.

In response to increased attention in literature, this work provides a qualitative review surrounding the application of silane-based coatings of metallic biomaterials for biomedical implants. Included herein is both a brief summary of existing knowledge and concepts regarding silane-based thin films, along with an analysis of recent peer-reviewed publications and advances towards their practical application for biomedical coatings. Specifically, the review identifies innovative silane-based coatings according to their molecular identity and film structure and analyses their impact on the biocorrosion resistance, protein adsorption, cell viability, and antimicrobial properties of the overall coated implant. It is shown that a range of common silanes clearly exhibit promising properties for biomedical implant coatings, but further work is needed, particularly on mechanisms of physiological interaction and characteristic effects of silane functional groups, before seeing clinical use. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2901-2918, 2018.

Chemical and Mechanical Properties of Experimental Dental Composites as a Function of Formulation and Postcuring Thermal Treatment.

This study evaluated the influence of formulation and thermal treatment on the degree of conversion, fracture toughness, flexural strength, and elastic modulus of experimental composites. Six composites were analyzed at BisGMA : TEGDMA molar ratios of 1 : 1 and 7 : 3 with filler at 30, 50, and 70 wt%. The degree of conversion was analyzed by Fourier transform infrared spectroscopy, fracture toughness was measured using the single-edge notched beam, and flexural strength and elastic modulus were measured with the 3-point bend test. For all tests, one-half of the specimens received thermal treatment at 170°C for 10 min. Data were analyzed by the Kruskal-Wallis or ANOVA/Tukey's test (α = 5%). The 1 : 1 BisGMA : TEGDMA ratio showed higher properties than the 7 : 3 ratio. Although the material with 70% filler had a conversion lower than the one with 50%, it showed higher mechanical properties. The thermal treatment improved all properties in all materials. Therefore, the use of an equimolar ratio of BisGMA : TEGDMA can be paired with 70 wt% filler to design dental composites that possess increased advantageous physical and chemical properties. Furthermore, the simple and low-cost method of thermal treatment proposed for use in clinical dentistry has been shown to effectively improve the properties of all evaluated materials.

Can Chlorhexidine enhance the Bond Strength of Self-etch and Etch-and-rinse Systems to Primary Teeth Dentin?

Introduction: Modifying the durability of resin bonding systems resulted in introducing materials with cross-link property, such as chlorhexidine (CHX) that can promote the strength of resin-dentin bonding. The aim of this study was evaluation of the effect of CHX on shear bond strength (SBS) of self-etch (SE) and etch-and-rinse (E&R) bonding systems to the primary teeth dentin. Materials and methods: In this in vitro study, 40 freshly extracted primary molars collected and were cut mesiodistally, and then the buccal and lingual surface enamel was grounded. The specimens were randomly divided into two groups: I: Single Bond adhesive and II: Clearfil SE Bond adhesive. Then, each group was divided into two subgroups: On the buccal surface of each sample CHX was applied for 30 seconds and on the lingual surface of (I2, II2 groups), CHX was not applied. The SBS (MPa) of samples was assessed using the Zwick universal testing machine. Data were analyzed by paired t-test and independent t-test using Statistical Package for the Social Sciences (SPSS), version 16. Results: The mean SBS was significantly higher in the Single Bond group with CHX (66.45 ± 8.3) than without CHX (25.43 ± 12.94) in the nonaging group (p = 0.002). There was no significant difference in the mean SBS in the Clearfil SE Bond group with CHX and without CHX in the aging and nonaging groups. Conclusion: CHX had positive influence on immediate SBS of Single Bond adhesive to primary teeth dentin. In addition, no positive effect has been seen in the Clearfil SE Bond system. Clinical significance: Now more researches are needed about the recommendation of CHX in resin restorations of primary teeth. Keywords: Chlorhexidine, Etch-and-rinse adhesive, Failure pattern, Self-etch adhesive, Shear bond strength.

Eighteen-month Clinical Study of Universal Adhesives in Noncarious Cervical Lesions.

OBJECTIVE: To evaluate the clinical performance of Scotchbond Universal (3M Oral Care) and Prime & Bond Elect (Dentsply Sirona) in the restoration of noncarious cervical lesions (NCCLs). METHODS AND MATERIALS: This was a randomized controlled clinical trial involving 63 subjects. Two hundred and three NCCLs were restored using Scotchbond Universal and Prime & Bond Elect using both an etch-and-rinse and a self-etch technique. Lesions were notch-shaped NCCLs, and the restorations were placed without any mechanical retention. Restorations were finished immediately after placement and scored with regard to retention, marginal discoloration, marginal adaptation, and secondary caries. Similar assessment of the restorations was performed 18 months after placement. Logistic regression was performed for each outcome separately with a compound symmetric variance-covariance structure assumed to consider a correlation of restorations within subjects. All analyses were conducted using SAS version 9.4 (SAS Inc). RESULTS: One hundred and fifty-eight teeth (77.8% of the restorations placed) in 46 subjects (73% of subjects enrolled) were available for the 18-month follow-up. A statistically significant difference was reached only for the comparison Scotchbond Universal/self-etch (SU_SE) and Prime & Bond Elect/etch-and-rinse (PBE_E&R) groups ( p=0.01), where a restoration with SU_SE was 66% less likely to maintain a score of Alpha for marginal discoloration than a restoration performed with PBE_E&R. CONCLUSIONS: Scotchbond Universal and Prime & Bond Elect presented acceptable clinical performance after 18 months of clinical service. However, Scotchbond Universal, when applied with a self-etch approach, did demonstrate a relatively high level of marginal discoloration when compared to the other groups.

Effect of At-home and In-office Bleaching on Marginal Microleakage in Composite Resin Restorations using Two Adhesive Systems.

AIM: The aim of this study is to assess marginal microleakage of cervical cavities restored with composite resins and two different adhesive techniques subjected to at-home and in-office bleaching. MATERIALS AND METHODS: In this randomized, blind laboratory experiment, 60 bovine teeth recently extracted were collected and divided into six groups (n = 10 each group). The teeth received cervical cavity preparations (2 mm × 3 mm × 1 mm) with enamel margins. Two different adhesive systems were used (Single Bond 2 and Clearfil SE Bond), in addition to composite resin (Z250). Restored teeth received two different bleaching gels (Opalescence PF and Opalescence Boost). Teeth were thermo-cycled and analyzed under confocal laser scanning microscopy. RESULTS: No significant differences were observed (p > 0.05) in microleakage scores between the two groups not subjected to bleaching nor between the four groups that received bleaching treatment (p > 0.05), regardless of the gel and adhesive system employed. However, when comparing nonbleached with bleached teeth, those not subjected to bleaching showed statistically lower marginal microleakage scores (p < 0.05). Data were statistically analyzed using the Kruskal-Wallis test followed by Student-Newman-Keuls post hoc test, with significance set at 5%. CONCLUSION: Marginal microleakage in composite resin restorations is influenced by the action of bleaching agents used both at-home and in-office, regardless of the adhesive system employed (total-etch or self-etch). CLINICAL SIGNIFICANCE: Both at-home and in-office bleaching agents have an influence on the adhesive interface of resin restorations, producing changes and inducing marginal leakage.

Histological effects of bisphenol-A on the reproductive organs of the adult male albino rat

Bisphenol-A (BPA) is widely used in the environment. The objective of this study was to investigate the histological reproductive toxicity of BPA in the adult male albino rats. Forty-five adult male albino rats were divided into 3 groups. Group I received normal saline orally daily (negative control); Group II received corn oil (0.5 ml/day) orally daily (positive control, and Group III were treated with BPA in a dose of 25 mg/kg B.W dissolved in corn oil for 30 days orally. Specimens from the testis, epididymis, prostate and seminal vesicles were collected for light microscopic examination. Blood samples were collected for serum testosterone level assessment. BPA caused histopathological alterations in the epithelium and connective tissues of all organs. Results of the serum testosterone level statistical analysis showed a highly significant decrease in BPA-treated group (III) as compared to the control groups (I & II). The epithelium of the accessory sex glands (prostate and seminal vesicles) responds to BPA by proliferative differentiation. The mean area percentage of collagen fibers stained with Masson's trichrome measured in the stroma of all organs was significantly increased. Also, there was a significant increase in the area percentage of positive inducible nitric oxide synthase (iNOS) immunoreactions in all organs. In conclusion, BPA induced DNA oxidative damage via iNOS activity in all reproductive organs

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A Novel Enamel and Dentin Etching Protocol Using α-hydroxy Glycolic Acid: Surface Property, Etching Pattern, and Bond Strength Studies.

OBJECTIVES: To determine the use of α-hydroxy glycolic acid (GA) as a surface pretreatment for dental restorative applications. The etching pattern of GA pretreatment of dental hard tissues was assessed by surface microhardness and scanning electron microscopy (SEM). The effectiveness of GA surface etching on the enamel and dentin resin bond strengths was assessed using two etchant application modes (rubbing and no rubbing) and three adhesive systems (Single Bond [SB], One Step Plus [OSP], and Scotchbond Universal [SBU]). METHODS: Knoop microhardness measurements were carried out on polished enamel and dentin surfaces before and after treatment with 35% GA, 35% phosphoric acid (PA), or distilled water (control group) for 30 seconds. The microtensile bond strength test was carried out on enamel and dentin. Ultrastructural analysis of the surface and interfacial interaction was qualitatively accomplished using SEM. RESULTS: Etching with either PA or GA significantly decreased the enamel microhardness, with GA being significantly less aggressive than PA ( p<0.001), while both acids showed similar decreases in dentin microhardness ( p=0.810). SEM revealed similar etching patterns of GA and PA, while apparently a thinner hybrid layer was observed for GA groups. In dentin, the bond strengths were statistically similar between PA and GA groups, regardless of the etchant application mode ( p>0.05). However, rubbing of GA enhanced the bond strength to enamel. PA and GA significantly increased the SBU bond strength to enamel when compared to SB and OSP ( p<0.05). CONCLUSIONS: GA effectively etched enamel and dentin surfaces, resulting in bond strength values similar to those associated with traditional PA. GA is a suitable enamel and dentin surface etchant for adhesive restorative procedures.

Effect of Fiber Post Cementation Timing on the Bond Strength of Resin Cements in Epoxy Resin-Obturated Canals.

This study evaluated the influence of timing after endodontic treatment and type of resin cement used on the bond strength of fiber posts to epoxy resin-obturated canals. A total of 80 bovine incisor roots were divided into four groups (n = 20). Glass fiber posts were cemented at two different times, immediately or 7 days after endodontic treatment, using either a dual-curing resin cement (RelyX ARC, 3M ESPE) or a self-adhesive resin cement (RelyX U200, 3M ESPE). Following post cementation, the samples were cross-sectioned into slices containing root dentin, cement, and fiber post at the cervical, mid, and apical root thirds. The push-out test was performed on a universal testing machine. Three-way analysis of variance for randomized blocks showed no significant effect within the triple interaction (P = .394) or between the double interactions cement-timing (P = .395), cement-root thirds (P = .996), and timing-root thirds (P = .331). The main factor cement revealed a significant effect, showing that regardless of the timing and root third, RelyX ARC provided significantly higher bond strength values than U200. Regardless of root third and timing, the dual-curing resin cement showed higher bond strength to root dentin when the canals were filled with epoxy resin-based cement.

Short- and Long-Term Bond Strength Between Resin Cement and Glass-Ceramic Using a Silane-Containing Universal Adhesive.

This study aimed to evaluate the effect of various silane-containing solutions on bonding between resin cement and glass ceramic after 24 hours and after six months of water storage. Glass-ceramic plaques (IPS e.max CAD) were sandblasted with aluminum oxide, etched with 10% hydrofluoric acid (HF), and divided into five "silane treatment" groups: RelyX Ceramic Primer (RCP), RelyX Ceramic Primer and Single Bond Plus (RCP+SB), Scotchbond Universal (SBU), Clearfil Ceramic Primer (CP), and no solution (HF-only control). Each group was divided into two "storage time" subgroups: 24 hours or six months in 37°C water. Eighteen resin cement cylinders (RelyX Ultimate) were bonded to each treatment group substrate (n=18) and then subjected to microshear testing. Failure mode was analyzed using scanning electron microscopy. Debond data were analyzed using a two-way analysis of variance and the Tukey post hoc test (α=0.05) as well as Weibull distributions. The factors "silane treatment," "storage time," (p<0.0001), and their interaction were statistically significant (p<0.0010). Group means (MPa±SD), RCP (24 hours: 27.2±3.1; six months: 18.0±4.9), and HF-only control (24 hours: 21.1±3.4; six months: 15.7±5.8) showed a reduced bond strength after six months of water storage, while RCP + SB (24 hours: 23.4±4.4; six months: 22.2±5.4), SBU (24 hours: 18.8±3.0; six months: 17.2±3.6), and CP (24 hours: 21.7±4.3; six months: 17.4±4.8) remained constant. Weibull analysis revealed that more reliable bond strengths were obtained after six months for SBU and RCP + SB. Evaluation by scanning electron microscopy revealed that all groups demonstrated hydrolytic degradation at six months of storage, but RCP + SB and SBU indicated less. Use of a separate application of silane and adhesive system improved short and long-term ceramic/resin cement bond strength.

Influence of Different Curing Modes on Polymerization Behavior and Mechanical Properties of Dual-Cured Provisional Resins.

This study determined the influence of curing mode on polymerization behavior and mechanical properties of dual-cured provisional resins. Three dual-cured bisacryl-based provisional resins were used: Tempsmart (TS; GC Corp), Luxatemp Automix Solar (LX; DMG Chemisch Pharmazeutishe Fabrik GmbH), and Integrity Multi·Cure (IG; Dentsply Caulk). A self-cured bisacryl-based provisional resin, Protemp Plus (PP; 3M ESPE) and a conventional poly(methyl methacrylate) (PMMA) provisional resin, Unifast III (UF; GC Corp) were used as controls. The inorganic filler content and coefficients of linear thermal expansion of the test materials were measured. Six specimens of each material were used to determine the flexural strength, elastic modulus, and resilience. The changes in ultrasound velocity during polymerization were measured. The average inorganic filler contents of the provisional resins, apart from UF, ranged from 24.4 to 39.3 wt%. The highest inorganic filler content was determined for LX, whereas TS showed the lowest value among the tested materials. The average coefficients of thermal expansion of the tested provisional resins ranged from 77.3 to 107.7 (×10-6/°C). TS and IG showed significantly lower thermal expansions than the other tested provisional resins. The mean flexural strengths of the provisional resins ranged from 70.4 to 122.6 MPa, the mean elastic moduli ranged from 1.8 to 3.7 GPa, and the mean resilience of the provisional resins ranged from 1.1 to 2.3 MJ/mm3, respectively. Dual-cured provisional resins showed significantly higher flexural strengths than the PMMA resin. However, in all cases, the light-curing mode showed significantly higher flexural strengths than the self-curing mode. In the initial polymerization phase, dual-cured resins in the light-curing mode showed a rapid increase in the speed of sound (V) during light irradiation, followed by a slower increase. Conversely, the dual-cured resins in the self-curing mode showed a slower initial increase, followed by a rapid increase. Although no significant difference in V was observed between 10 and 15 minutes in the light-curing mode of all tested dual-cured resins, a significantly higher V value was obtained at 15 minutes than at 10 minutes in the self-curing modes for LX and IG. Regardless of the curing mode, tested dual-cured provisional resins showed superior mechanical properties than the conventional PMMA provisional resin. However, dual-cured provisional resin flexural properties and polymerization behavior were affected by the curing mode. This study indicated that the light-curing mode might be recommended for all dual-cured provisional resins because of the enhancement of their mechanical properties and reduction of chair time.

Survival of sealants in molars affected by molar-incisor hypomineralization: 18-month follow-up.

The objective of this study was to evaluate the clinical survival of sealants applied in first permanent molars (FPMs) affected by molar-incisor hypomineralization (MIH), at 18 months of follow-up. Forty-one first permanent molars were selected from 21 children, 6-8 years of age. MIH was classified by one calibrated examiner (kappa = 0.80) according to EAPD criteria. The inclusion criteria were fully erupted FPMs with MIH or sound FPMs (without MIH) for which sealant treatment was indicated. The FPMs were assigned to two groups: CG (control group) and HG (MIH group). Both groups were treated with sealant (FluroShield). Clinical follow-up was performed from baseline to 18 months to assess anatomical form, marginal adaptation, retention and presence of caries, according to criteria set by the United States Public Health Service-Modified, and was conducted by a blinded examiner (kappa = 0.80). The actuarial method was used to evaluate the survival of the sealants. The survival rates for the groups were compared using Fisher's exact test (α = 5%). The cumulative survival rates were 81% at 1 month, 68.8% at 6 months, 68.8% at 12 months, and 62.6% at 18 months for CG, and 88% at 1 month, 84% at 6 months, 76% at 12 months, and 72% at 18 months for HG. No significant difference was found between the groups. The sealants in molars affected by MIH presented a survival rate similar to the sealants in the control, suggesting that sealants may be an adequate approach for preventing carious lesions in MIH-affected molars.

Longevity of metal-ceramic crowns cemented with self-adhesive resin cement: a prospective clinical study

Resin cements are often used for single crown cementation due to their physical properties. Self-adhesive resin cements gained widespread due to their simplified technique compared to regular resin cement. However, there is lacking clinical evidence about the long-term behavior of this material. The aim of this prospective clinical trial was to assess the survival rates of metal-ceramic crowns cemented with self-adhesive resin cement up to six years. One hundred and twenty-nine subjects received 152 metal-ceramic crowns. The cementation procedures were standardized and performed by previously trained operators. The crowns were assessed as to primary outcome (debonding) and FDI criteria. Statistical analysis was performed using Kaplan-Meier statistics and descriptive analysis. Three failures occurred (debonding), resulting in a 97.6% survival rate. FDI criteria assessment resulted in scores 1 and 2 (acceptable clinical evaluation) for all surviving crowns. The use of self-adhesive resin cement is a feasible alternative for metal-ceramic crowns cementation, achieving high and adequate survival rates.

Effect of Airborne Particle Abrasion on Microtensile Bond Strength of Total-Etch Adhesives to Human Dentin.

Aim of this study was to investigate a specific airborne particle abrasion pretreatment on dentin and its effects on microtensile bond strengths of four commercial total-etch adhesives. Midcoronal occlusal dentin of extracted human molars was used. Teeth were randomly assigned to 4 groups according to the adhesive system used: OptiBond FL (FL), OptiBond Solo Plus (SO), Prime & Bond (PB), and Riva Bond LC (RB). Specimens from each group were further divided into two subgroups: control specimens were treated with adhesive procedures; abraded specimens were pretreated with airborne particle abrasion using 50 µm Al2O3 before adhesion. After bonding procedures, composite crowns were incrementally built up. Specimens were sectioned perpendicular to adhesive interface to produce multiple beams, which were tested under tension until failure. Data were statistically analysed. Failure mode analysis was performed. Overall comparison showed significant increase in bond strength (p < 0.001) between abraded and no-abraded specimens, independently of brand. Intrabrand comparison showed statistical increase when abraded specimens were tested compared to no-abraded ones, with the exception of PB that did not show such difference. Distribution of failure mode was relatively uniform among all subgroups. Surface treatment by airborne particle abrasion with Al2O3 particles can increase the bond strength of total-etch adhesives.