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Objectives: This in vitro study examined the marginal integrity of experimental composite materials doped with bioactive glass (BG). Materials and methods: Class-II MOD cavities were prepared and restored with one of the following composite materials: a commercial composite material as a reference (Filtek Supreme XTE), an experimental composite doped with BG 45S5 (C-20), and an experimental composite doped with a fluoride-containing BG (F-20). Six experimental groups (n = 8) were used, as each of the three composites was applied with (+) or without (-) a universal adhesive (Adper Scotchbond Multipurpose). All specimens were subjected to thermocycling (10,000 x, 5–55 °C) and then additionally stored in artificial saliva for eight weeks. Scanning electron micrographs of the mesial and the distal box were taken at three time points (initial, after thermocycling, and after eight weeks of storage in artificial saliva). The margins were classified as “continuous” and “non-continuous” and the percentage of continuous margins (PCM) was statistically analyzed (α = 0.05). Results: In most experimental groups, thermocycling led to a significant decrease in PCM, while the additional 8-week aging had no significant effect. F-20 + performed significantly better (p = 0.005) after 8 weeks storage in artificial saliva than the reference material with adhesive, while no statistically significant differences were observed at the other two time points. C-20 + exhibited significantly better PCM than the reference material with adhesive after thermocycling (p = 0.026) and after 8 weeks (p = 0.003). Conclusions: Overall, the experimental composites with BG showed at least as good marginal adaptation as the commercial reference, with an indication of possible re-sealing of marginal gaps. Clinical relevance: Maintaining or improving the marginal integrity of composite restorations is important to prevent microleakage and its likely consequences such as pulp irritation and secondary caries. [ABSTRACT FROM AUTHOR]

Purpose: To investigate marginal integrity of restorations applied with preheated and non-preheated composite, flowable composite, sonically activated composite, and a new thermo-viscous bulk-fill composite using near-infrared technology for preheating, in class V cavities of human molars. Materials and Methods: Standardized cavities were prepared on the buccal surfaces of 60 human mandibular molars and restored with one of the following resin composite materials after application of an etch-and-rinse adhesive (Opti-Bond FL, Kerr): non-preheated or preheated conventional composite (Filtek Supreme XTE, 3M Oral Care), preheated thermo-viscous composite (VisCalor bulk, Voco), soncially activated composite (SonicFill 3, Kerr), or flowable composite (Filtek Supreme XTE Flowable, 3M Oral Care) applied in bulk or as a lining material using the snow-plow technique. After light curing and polishing, the percentage of continuous margins (PCM) of the restorations in enamel and dentin was assessed using SEM both before and after thermomechanical loading (TML). TML was carried out with 3000 thermal cycles (5°C-50°C) and a simultaneous mechanical stress application with 1.2 million load-cycles (1.7 Hz, 49 N) in a computer-controlled masticator. Non-parametric statistical analysis was performed using Wilcoxon, Kruskal- Wallis, and Mann-Whitney U-tests (2= 0.05). Results: All groups revealed a significant decline in marginal integrity after TML in both enamel and dentin. Although the flowable group in enamel and the snow-plow group in dentin showed the highest PCM before TML, the differences between the groups were compensated after TML. Conclusion: All of the tested composites and application methods showed similar marginal integrities after thermomechanical loading and can be recommended for clinical implementation. [ABSTRACT FROM AUTHOR]

The aim was to investigate the influence of endodontic irrigation solutions and protocols on the micro-tensile bond strength (μTBS) to dentin using an etch-and-rinse (ER) or self-etch (SE) adhesive approach. Eighty extracted human molars were ground to dentin. After pretreating for 27 min (21 min–3 min–3 min) with five different endodontic irrigation protocols (Group 1: NaOCl–EDTA–NaOCl; Group 2: NaOCl–NaOCl–EDTA; Group 3: NaOCl–NaCl–NaOCl; Group 4: Dual Rinse–Dual Rinse–Dual Rinse; Group 5: NaCl–NaCl–NaCl), an ER (Optibond FL, Kerr) or a SE (Clearfil SE Bond, Kuraray) adhesive system was applied. After light-curing, composite build-ups were made and cut into dentin-composite sticks. μTBS and failure modes were analyzed. Nonparametric statistical analyses (α = 0.05) were performed for comparison of the five groups within each type of adhesive as well as between the two adhesive systems used. The use of an ER instead of a SE adhesive system resulted in significantly higher μTBS for all irrigation protocols except for group 1 (NaOCl–EDTA–NaOCl) and 2 (NaOCl–NaOCl–EDTA). A statistical difference between the five different endodontic irrigation protocols was only found within the SE adhesive group, where group 1 (NaOCl–EDTA–NaOCl) achieved highest values. The use of an ER adhesive system cancels out the effect of the endodontic irrigation solution. The highest μTBS was achieved when using a NaOCl–EDTA–NaOCl-irrigation protocol in combination with Clearfil SE Bond, which shows that the selection of the endodontic irrigation should match the corresponding SE adhesive system. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the reparability of aged and fresh resin composite after different mechanical surface pretreatments. Materials and Methods: Sixty composite specimens (Filtek Supreme XTE, 3M Oral Care) were either aged by thermal cycling (5000 cycles, 5-55°C) and six months of water storage, or immediately processed within 5 min after polymerization. Both aged and fresh specimens were either ground with fine (46-µm) or coarse (100-µm) diamond burs and then silanized or sandblasted with aluminum oxide (Al2O3) and silanized. In the negative control group, no mechanical surface pretreatment or silanization was performed. Specimens (n = 6 per group) were repaired with an adhesive (OptiBond FL, Kerr) and a resin composite (Filtek Supreme XTE). Directly adhered composite-to-composite increments served as the positive control group. After thermoycling, microtensile repair bond strength was assessed and statistically analyzed (α = 0.05). Results: Aged composite surfaces revealed significantly lower repair bond strength than immediately repaired composite. The negative control group demonstrated the significantly lowest microtensile bond strength of all groups. No significant differences in repair bond strength were observed between the different mechanical pretreatments for both aged and fresh specimens. The repair bond strength of fresh composite pretreated with a fine diamond bur + Al2O3 + silane or a coarse diamond bur with/without Al2O3 + silane did not differ significantly from the positive control group. Conclusion: The age of the repaired composite has a greater influence on repair bond strength than does the type of composite surface pretreatment. [ABSTRACT FROM AUTHOR]

Background: Reducing the necessary time to restore primary teeth improves the cooperation of paediatric patients. This study aimed to investigate the marginal integrity of restorations prepared with a bulk-fill resin-based composite (RBC) containing additional fragmentation chain transfer (AFCT) compared to a conventional RBC when light cured with a rapid high-irradiance (3 s) and a regular (10 s) curing mode. Methods: Forty class-II cavities were prepared in 40 primary molars. The molars were randomly divided into four groups based on the applied light-curing modes (regular: 10 s @ 1200 mW/cm2 or high-irradiance: 3 s @ 3000 mW/cm2) and the used restorative material (AFCT-containing bulk-fill RBC "Power Fill" or AFCT-free conventional RBC "Prime"). After thermo-mechanical loading, the marginal integrity was analysed using scanning electron microscopy. A beta regression model and pairwise comparisons were used to statistically analyse the data. Results: The mean marginal integrity (% ± SD) of the restorations for each group was as follows: Power Fill (10 s: 79.7 ± 15.6) (3 s: 77.6 ± 11.3), Prime (10 s: 69.7 ± 11.1) (3 s: 75.0 ± 9.7). The difference between the RBCs for the same light-curing mode was statistically significant (p ≤ 0.05). The difference between the light-curing modes for the same RBC was not statistically significant (p ˃ 0.5). Conclusions: AFCT-containing bulk-fill RBC "Power Fill" achieves similar marginal integrity when light-cured with either high-irradiance or regular light-curing modes. "Power Fill" achieves better marginal integrity than the conventional RBC "Prime" regardless of the applied light-curing mode. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate microhardness, mass changes during 1-year water immersion, water sorption/solubility, and calcium phosphate precipitation of experimental composites functionalized with 5–40 wt% of two types of bioactive glass (BG): 45S5 or a customized low-sodium fluoride-containing formulation. Vickers microhardness was evaluated after simulated aging (water storage and thermocycling), water sorption and solubility were tested according to ISO 4049, and calcium phosphate precipitation was studied by scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. For the composites containing BG 45S5, a significant reduction in microhardness was observed with increasing BG amount. In contrast, 5 wt% of the customized BG resulted in statistically similar microhardness to the control material, while higher BG amounts (20 and 40 wt%) resulted in a significant improvement in microhardness. Water sorption was more pronounced for composites containing BG 45S5, increasing 7-fold compared to the control material, while the corresponding increase for the customized BG was only 2-fold. Solubility increased with higher amounts of BG, with an abrupt increase at 20 and 40 wt% of BG 45S5. Calcium phosphate was precipitated by all composites with BG amounts of 10 wt% or more. The improved properties of the composites functionalized with the customized BG indicate better mechanical, chemical, and dimensional stability without compromising the potential for calcium phosphate precipitation. [ABSTRACT FROM AUTHOR]

Objectives : To assess the behavior of dual-cure and conventional bulk-fill composite materials on real-time linear shrinkage, shrinkage stress, and degree of conversion. Materials and methods: Two dual-cure bulk-fill materials (Cention, Ivoclar Vivadent (with ion-releasing properties) and Fill-Up!, Coltene) and two conventional bulk-fill composites (Tetric PowerFill, Ivoclar Vivadent; SDR flow + , Dentsply Sirona) were compared to conventional reference materials (Ceram.x Spectra ST (HV), Dentsply Sirona; X-flow; Dentsply Sirona). Light curing was performed for 20 s, or specimens were left to self-cure only. Linear shrinkage, shrinkage stress, and degree of conversion were measured in real time for 4 h (n = 8 per group), and kinetic parameters were determined for shrinkage stress and degree of conversion. Data were statistically analyzed by ANOVA followed by post hoc tests (α = 0.05). Pearson's analysis was used for correlating linear shrinkage and shrinkage force. Results: Significantly higher linear shrinkage and shrinkage stress were found for the low-viscosity materials compared to the high-viscosity materials. No significant difference in degree of conversion was revealed between the polymerization modes of the dual-cure bulk-fill composite Fill-Up!, but the time to achieve maximum polymerization rate was significantly longer for the self-cure mode. Significant differences in degree of conversion were however found between the polymerization modes of the ion-releasing bulk-fill material Cention, which also exhibited the significantly slowest polymerization rate of all materials when chemically cured. Conclusions: While some of the parameters tested were found to be consistent across all materials studied, heterogeneity increased for others. Clinical relevance: With the introduction of new classes of composite materials, predicting the effects of individual parameters on final clinically relevant properties becomes more difficult. [ABSTRACT FROM AUTHOR]

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The accumulation of caries-preventive compounds on sound enamel is crucial in order to improve the inhibition of carious lesion initiation. The aim of this research was to investigate the initial accumulation of cerium, oligopeptide p11-4, and fluoride from NaF or amine fluoride (AmF) on sound enamel in vitro by means of energy dispersive X-ray spectroscopy (EDX). Polished bovine enamel specimens (n = 120 from 60 teeth) were fabricated. Out of these, 12 specimens each were treated with CeCl3 (cerium(III) chloride heptahydrate 25%), oligopeptide p11-4 (Curodont Repair, Credentis), NaF (10,000 ppm F−), AmF (amine fluoride, Elmex Fluid, CP-GABA GmbH, 10,000 ppm F−), or Aqua demin (control). After rinsing with water, the surface elemental composition (Ce, N, F, Ca, P, O, Na, Mg) was measured (EDX; EDAX Octane Elect detector, APEX v2.0), expressed in atomic percent (At%) and analyzed (non-parametric statistics, α = 0.05, error rates method). Another 12 specimens per treatment group were fabricated and used for analyzing accumulation in cross-sections with EDX linescans and two-dimensional EDX-mappings. The surface median atomic percent of cerium (At%Ce) was 0.8 for CeCl3, but no Ce was found for any other group. N, specifically for oligopeptide p11-4, could not be detected. Fluorine could only be detected on fluoridated surfaces. The median atomic percent of fluorine (At%F) was 15.2 for NaF and 17.0 for AmF. The Ca/P ratio increased significantly compared to the control following the application of NaF and AmF (p < 0.001), but decreased significantly for CeCl3 (p < 0.001). In cross-sectioned specimens of the CeCl3-group, 12.5% of the linescans revealed cerium at the enamel surface, whereas 83.3% of the NaF linescans and 95.8% of the AmF linescans revealed fluorine at the enamel surface. Following the application of oligopeptide p11-4, no traces of N were detectable. In the depth of the samples, no signal was detected for any of the corresponding elements exceeding the background noise. Cerium and fluorine (from both NaF and AmF), but not the oligopeptide p11-4, precipitated on sound enamel. [ABSTRACT FROM AUTHOR]

This study investigated the influence of conventional (10 s at 1160 mW/cm2) and fast high-irradiance (3 s at 2850 mW/cm2) light curing on the micro-tensile bond strength (μTBS) of bulk-fill resin composites bonded to human dentin. Sixty-four extracted human molars were ground to dentin and randomly assigned into eight groups (n = 8 per group). After application of a three-step adhesive system (Optibond FL), four different bulk-fill composites (two sculptable and two flowable composites) were placed. Of these, one sculptable (Tetric PowerFill) and one flowable (Tetric PowerFlow) composite were specifically developed for fast high-irradiance light curing. Each composite was polymerized with the conventional or the fast high-irradiance light-curing protocol. The specimens were cut into dentin-composite sticks, μTBS was determined and failure modes were analyzed. Statistical analysis was performed using t-test for independent observations and one-way ANOVA. A statistical difference between the curing protocols was only found for Tetric PowerFlow, where the conventional protocol (23.8 ± 4.2 MPa) led to significantly higher values than the fast high-irradiance light-curing protocol (18.7 ± 3.7 MPa). All other composite materials showed statistically similar values for both polymerization protocols. In conclusion, the use of fast high-irradiation light curing has no negative influence on the μTBS of the investigated high-viscosity bulk-fill composites. However, it may reduce the dentin bond strength of flowable bulk-fill composite. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine the applicability of bioactive and antibacterial nanoparticles to an experimental adhesive. The adhesive (60 wt% BisGMA, 15 wt% TEGDMA, 25 wt% HEMA) was mixed with combinations of 5 wt% methacryl-functionalized polyhedral oligomeric silsesquioxane (MA-POSS) and one kind of bioactive/antibacterial nanoparticles: 1 wt% core-shell silica-silver nanoparticle (SiO2@Ag), 1 wt% bioactive glass with bismuth (BAG-Bi) or 1 wt% calcium phosphate (CAP). Pure adhesive served as control. The physicochemical (degree of conversion (DC), linear shrinkage (LS), shear and complex viscosity, water sorption (WS), sol fraction (SF)), biological (antimicrobial effect) and bioactive (mineral precipitation) properties were investigated. DC and LS remained unchanged. The combination of BAG-Bi/MA-POSS resulted in a significantly increased WS and SF compared to control. In addition, the combination of CAP/MA-POSS slightly increased the shear viscosity of the adhesive. The addition of the nanoparticles did not influence the antimicrobial effects compared to the pure adhesive. Improved mineral inducing capacity could be detected in all nanoparticle combinations. The combination of bioactive and/or antibacterial nanoparticles showed improved mineral inducing capacity, but no antibacterial properties. The material properties were not or only slightly affected. [ABSTRACT FROM AUTHOR]

This study evaluated the flexural properties of an experimental composite series functionalized with 5–40 wt% of a low-Na F-containing bioactive glass (F-series) and compared it to another experimental composite series containing the same amounts of the conventional bioactive glass 45S5 (C-series). Flexural strength and modulus were evaluated using a three-point bending test. Degree of conversion was measured using Fourier-transform infrared spectroscopy. Weibull analysis was performed to evaluate material reliability. The control material with 0 wt% of bioactive glass demonstrated flexural strength values of 105.1–126.8 MPa). In the C-series, flexural strength ranged between 17.1 and 121.5 MPa and was considerably more diminished by the increasing amounts of bioactive glass than flexural strength in the F-series (83.8–130.2 MPa). Analogously, flexural modulus in the C-series (0.56–6.66 GPa) was more reduced by the increase in bioactive glass amount than in the F-series (5.24–7.56 GPa). The ISO-recommended "minimum acceptable" flexural strength for restorative resin composites of 80 MPa was achieved for all materials in the F-series, while in the C-series, the materials with higher bioactive glass amounts (20 and 40 wt%) failed to meet the requirement of 80 MPa. The degree of conversion in the F-series was statistically similar or higher compared to that of the control composite with no bioactive glass, while the C-series showed a declining degree of conversion with increasing bioactive glass amounts. In summary, the negative effect of the addition of bioactive glass on mechanical properties was notably less pronounced for the customized bioactive glass than for the bioactive glass 45S5; additionally, mechanical properties of the composites functionalized with the customized bioactive glass were significantly less diminished by artificial aging. Hence, the customized bioactive glass investigated in the present study represents a promising candidate for functionalizing ion-releasing resin composites. [ABSTRACT FROM AUTHOR]

Experimental dental resin composites containing copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) were developed to impart anti-bacterial properties. Increasing amounts of Cu-MBGN (0, 1, 5 and 10 wt%) were added to the BisGMA/TEGDMA resin matrix containing micro- and nano-fillers of inert glass, keeping the resin/filler ratio constant. Surface micromorphology and elemental analysis were performed to evaluate the homogeneous distribution of filler particles. The study investigated the effects of Cu-MBGN on the degree of conversion, polymerization shrinkage, porosity, ion release and anti-bacterial activity on S. mutans and A. naeslundii. Experimental materials containing Cu-MBGN showed a dose-dependent Cu release with an initial burst and a further increase after 28 days. The composite containing 10% Cu-MBGN had the best anti-bacterial effect on S. mutans, as evidenced by the lowest adherence of free-floating bacteria and biofilm formation. In contrast, the 45S5-containing materials had the highest S. mutans adherence. Ca release was highest in the bioactive control containing 15% 45S5, which correlated with the highest number of open porosities on the surface. Polymerization shrinkage was similar for all tested materials, ranging from 3.8 to 4.2%, while the degree of conversion was lower for Cu-MBGN materials. Cu-MBGN composites showed better anti-bacterial properties than composites with 45S5 BG. [ABSTRACT FROM AUTHOR]

This study investigated polymerization kinetics, linear shrinkage, and shrinkage stress development for six contemporary composite materials of different viscosities cured using radiant exitances of 1100–2850 mW/cm2. Real-time measurements of degree of conversion, linear shrinkage, and shrinkage stress were performed over 5 min using Fourier-transform infrared spectrometry, a custom-made linometer, and a custom-made stress analyzer, respectively. For most tested variables, the factor "material" had a higher effect size than the factor "curing protocol". Maximum polymerization rate and maximum shrinkage stress rate were the most affected by changes in curing conditions. In contrast, no significant effects of curing conditions were identified within each material for shrinkage stress values measured at the end of the 5 min observation period. Linear shrinkage and shrinkage stress values measured after 5 min were closely correlated (R = 0.905–0.982). The analysis of polymerization kinetics suggested that the two composites specifically designed for rapid light-curing responded to higher radiant exitances differently than other composites. Polymerization kinetics and shrinkage stress behavior of contemporary restorative composite materials of different viscosities were overall more affected by material type than differences in curing conditions. Subtle differences in polymerization kinetics behavior shown by the two composites specifically designed for rapid high-intensity light-curing did not translate into significant differences in the development of polymerization shrinkage stress. [ABSTRACT FROM AUTHOR]

Bulk-fill composites enable timesaving and less technical-sensitive application of restorations. This study investigated and compared the marginal integrity of classical and bulk-fill composite restorations in primary and permanent molars before and after thermo-mechanical loading (TML). Two Class II cavities were prepared in each of 20 primary and 20 permanent molars. The molars were randomised in four groups for each molar type. Groups 1 and 5 were restored with a high-viscous bulk-fill composite (Tetric PowerFill), groups 2 and 6 were restored with a flowable bulk-fill composite (Tetric PowerFlow), groups 3 and 7 were restored with a high-viscous classical composite (Tetric Prime), and groups 4 and 8 were restored with a flowable classical composite (Tetric EvoFlow). In permanent molars, the flowable composites were covered with a 2-mm layer of high-viscous composite (groups 6 and 8). The restorations were subjected to TML in a custom-made chewing machine (5–50 °C, 2 min dwelling time, × 1000; 400 ,000 loading cycles, 1.7 Hz, 49 N), and quantitative marginal analysis was conducted using scanning electron microscopy. Marginal integrity of each restoration was calculated as a percentage of continuous margins before and after TML. The tested high-viscous bulk-fill restoration showed similarly high marginal integrity in primary and permanent molars as the classical restoration. The tested flowable bulk-fill restoration showed the lowest marginal integrity compared to all other restorations after TML. In contrast to flowable bulk-fill restorations, high-viscous bulk-fill restorations show similar marginal integrity as classical hybrid composite restorations after TML, in both primary and permanent molars. [ABSTRACT FROM AUTHOR]

We embedded copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) with antibacterial and ion-releasing properties into experimental dental composites and investigated the effect of Cu-MBGN on the polymerisation properties. We prepared seven composites with a BisGMA/TEGDMA (60/40) matrix and 65 wt.% total filler content, added Cu-MBGN or a combination of Cu-MBGN and silanised silica to the silanised barium glass base, and examined nine parameters: light transmittance, degree of conversion (DC), maximum polymerisation rate (Rmax), time to reach Rmax, linear shrinkage, shrinkage stress (PSS), maximum PSS rate, time to reach maximum PSS rate, and depth of cure. Cu-MBGN without silica accelerated polymerisation, reduced light transmission, and had the highest DC (58.8 ± 0.9%) and Rmax (9.8 ± 0.2%/s), but lower shrinkage (3 ± 0.05%) and similar PSS (0.89 ± 0.07 MPa) versus the inert reference (0.83 ± 0.13 MPa). Combined Cu-MBGN and silica slowed the Rmax and achieved a similar DC but resulted in higher shrinkage. However, using a combined 5 wt.% Cu-MBGN and silica, the PSS resembled that of the inert reference. The synergistic action of 5 wt.% Cu-MBGN and silanised silica in combination with silanised barium glass resulted in a material with the highest likelihood for dental applications in future. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of pretreating demineralized enamel with a caries infiltrant on the margin integrity of Class V composite restorations bonded with different adhesives. Materials and Methods: A total of 60 specimens from bovine incisors were demineralized (21 days, acid buffer, pH 4.95) to create artificial enamel lesions, and circular Class V cavities were prepared. Cavities of half of the specimens were treated with either an unfilled etch-and-rinse adhesive (Syntac Classic; Ivoclar Vivadent), a filled etch and-rinse adhesive (Optibond FL; Kerr), or a self-etch adhesive (iBond Self Etch; Heraeus Kulzer) (n = 10 per group). Demineralized enamel of the other half of the specimens was pretreated with a caries infiltrant (Icon; DMG) prior to adhesive application. All cavities were restored with a nanofilled composite material and thermocycled (5000 ×, 5°C-55°C). Margin integrity was evaluated using scanning electron microscopy, and the percentage of continuous margin was statistically analyzed (p < 0.05). Results: The significantly highest margin integrity was observed for Optibond FL, whether or not demineralized enamel was pretreated with the infiltrant. Pretreatment of demineralized enamel with the infiltrant resulted in a significant increase in margin integrity when the unfilled etch-and-rinse adhesive (Syntac Classic) or the self-etch adhesive (iBond Self Etch) was subsequently applied, but showed no significant improvement in combination with the filled etch-and-rinse adhesive (Optibond FL). Conclusion: Application of a caries infiltrant can improve margin integrity of composite fillings in demineralized enamel when used in combination with the examined self-etch and unfilled adhesives. [ABSTRACT FROM AUTHOR]

Purpose: To determine the effects of contamination of tooth cavities by hemostatic agents applied after blood contamination on marginal adaptation of composite restorations bonded with etch-and-rinse and self-etch adhesives. Materials and Methods: Cervical cavities (n = 10 per group) were contaminated with blood and subsequently treated with aluminum chloride (Racestyptine) or ferric sulfate (Astringedent, ViscoStat) hemostatic agents. After water rinsing, composite restorations were placed using either an etch-and-rinse (OptiBond FL) or self-etch (Opti-Bond All-in-One) adhesive. EDS-based elemental surface analysis was performed, and marginal integrity was evaluated using SEM both before and after thermomechanical loading. The percentage of continuous margins in enamel (%CEM) and dentin (%CDM) was statistically analyzed (p < 0.05). Results: No statistically significant differences in %CEM and %CDM were observed between hemostatic-contaminated groups and uncontaminated controls after thermomechanical loading, irrespective of the adhesive used. Specimens contaminated with aluminum-chloride-based Racestyptine showed a significantly higher final %CEM when the etch-and-rinse adhesive was applied (OptiBond FL) than with the self-etch adhesive (OptiBond All-in-One). Conclusion: Cavity contamination with hemostatic agents, applied after blood contamination and removed with water spray, does not compromise marginal adaptation in enamel and dentin. In the case of contamination by an aluminum-chloride hemostatic agent, the tested etch-and-rinse approach resulted in a higher percentage of continuous enamel margins of composite restorations than did the self-etch approach. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the influence of different pretreatments on the microtensile bond strength (μTBS) of an etchand- rinse adhesive to eroded dentin. Materials and Methods: Thirty-six human teeth were ground down to their dentin layer and randomly divided into six groups (G1-G6; n = 6), G1 being the control group. Only in the test groups (G2-G6) were samples subjected to erosion using citric acid (pH 2.6) 10 x 2 min per day for five days. Between the erosive attacks, samples were stored in artificial saliva. After pretreatment - none (G1); none (G2); 2% chlorhexidine (30 s) (G3); prolonged primer application (1 min) (G4); roughening with a diamond bur (G5) and 10.5% NaOCl (1 min) (G6) - the adhesive Opti- Bond FL was applied. After the application of composite, samples were stored in water (7 d) and μTBS was determined. Data were evaluated using one-way ANOVA and Dunnett-T post-hoc test (p < 0.05). Results: Eroded dentin without pretreatment (G2) resulted in significant reduction of μTBS compared with uneroded dentin (G1). μTBS after pretreatment with a diamond bur (G5) or NaOCl (G6) was not significantly different from that of the uneroded control group (G1). μTBS after pretreatment with chlorhexidine (G3) or with prolonged primer application (G4) was significantly lower than in the uneroded control group (G1), and not significantly different from the eroded control group (G2). Conclusion: The present data suggests that μTBS to eroded dentin pretreated with bur abrasion or NaOCl is similar to the μTBS to sound, uneroded dentin. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether reducing the light-curing time of resin-based surface sealants influences their potential to prevent erosion, as well as their mechanical stability and degree of conversion.Materials and Methods: 240 bovine dentin samples were randomly divided into 10 groups (1-10). The 24 samples of one group remained unsealed and served as control. Three groups were sealed with Seal&Protect, another three groups with K-0184 (experimental sealant), and the remaining three groups with Syntac Classic. One group of each sealant was light cured for 10 s, another group of that sealant for 5 s, and the last group of the respective sealant for 2 s at 1014 mW/cm2. After 7-day water storage, the first measurement of sealant permeability was performed. The samples were stored in hydrochloric acid (pH 2.3) for 24 h and the dentin calcium release was measured by atomic absorption spectroscopy. Following thermomechanical loading (5000 cycles, 5°/50°C, 12,000 brushing strokes), the second measurement of sealant permeability was performed. Additionally, the sealants' degrees of conversion (DC) were determined by FTIR spectroscopy.Results: For the first and second measurements, no significant difference in the permeability of the sealants was observed when the light-curing duration was shortened. Additionally, no significant difference in the stability of the respective sealants was observed when light cured for different durations. Regarding DC, a significant influence of the light-curing duration was observed (p = 0.000).Conclusion: Shortening the light-curing time has no influence on permeability and stability of the investigated sealants. However, short light-curing times (2 s or 5 s) decrease the DC of the tested sealants. [ABSTRACT FROM AUTHOR]

This study investigated the potential of adhesive coating for hindering the reactivity of ion-releasing dental restorative materials. Experimental composites were prepared by replacing 10 or 20 wt% of reinforcing fillers with two types of bioactive glass. A glass ionomer, a giomer, and an alkasite were used as representatives of commercial ion-releasing materials. Restorative material specimens were coated with an etch-and-rinse adhesive, 1-step self-etch adhesive, 2-step self-etch adhesive, or left uncoated. The specimens were immersed in a lactic acid solution and ion concentrations were measured in 4 days intervals for 32 days (atomic absorption spectrometry for calcium, UV–Vis spectrometry for phosphate, ion-selective electrode for fluoride, and pH-meter for pH values). The adhesive coating reduced ion release between 0.3 and 307 times, in a significantly material- and adhesive-dependent manner. Fluoride release was most highly impaired, with the reduction of up to 307 times, followed by phosphate and calcium release, which were reduced up to 90 and 45 times, respectively. The effect of different adhesive systems was most pronounced for phosphate release, with the following rankings: uncoated ≥ 2-step self-etch adhesive ≥ 1-step self-etch adhesive ≥ etch-and-rinse adhesive. The differences among adhesives were less pronounced for calcium and fluoride. It was concluded that the resinous adhesive layer can act as a barrier for ion release and diminish the beneficial effects of remineralizing restorative materials. [ABSTRACT FROM AUTHOR]

The objective was to evaluate new commercially available ion-releasing restorative materials and compare them to established anti-cariogenic materials. Four materials were tested: alkasite Cention (Ivoclar Vivadent) in self-cure or light-cure mode, giomer Beautifil II (Shofu), conventional glass-ionomer Fuji IX (GC), and resin composite Tetric EvoCeram (Ivoclar Vivadent) as a control. Flexural strength, flexural modulus, and Weibull modulus were measured one day, three months, and after three months with accelerated aging in ethanol. Water sorption and solubility were evaluated for up to one year. Degree of conversion was measured during 120 min for self-cured and light-cured Cention. In this study, Beautifil II was the ion-releasing material with the highest flexural strength and modulus and with the best resistance to aging. Alkasite Cention showed superior mechanical properties to Fuji IX. Weibull analysis showed that the glass-ionomer had the least reliable distribution of mechanical properties with the highest water sorption. The solubility of self-cured alkasite exceeded the permissible values according to ISO 4049. Degree of conversion of light-cured Cention was higher than in self-cure mode. The use of alkasite Cention is recommended only in the light-cure mode. [ABSTRACT FROM AUTHOR]

This study aimed to investigate polymerization kinetics and curing light transmittance of two series of experimental dental resin composites filled with 0–40 wt% of either 45S5 bioactive glass (BG) or a customized low-Na F-containing BG. Polymerization kinetics in 0.1-mm and 2-mm thick layers were investigated through real-time degree of conversion measurements using a Fourier transform infrared (FTIR) spectrometer. FTIR spectra were continuously collected at a rate of 2 s−1 during light-curing (1340 mW/cm2). Light transmittance through 2-mm thick composite specimens was measured using a UV–Vis spectrometer at a rate of 20 s−1. Unlike BG 45S5, which led to a dose-dependent reduction in the rate and extent of polymerization, the customized low-Na F-containing BG showed a negligible influence on polymerization. The reduction in light transmittance of experimental composites due to the addition of the low-Na F-containing BG did not translate into impaired polymerization kinetics. Additionally, the comparison of polymerization kinetics between 0.1-mm and 2-mm thick layers revealed that polymerization inhibition identified for BG 45S5 was not mediated by an impaired light transmittance, indicating a direct effect of BG 45S5 on polymerization reaction. A customized low-Na F-containing BG showed favourable behaviour for being used as a functional filler in light-curing dental resin composites. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate whether experimental and commercial dental restorative materials with functional fillers can exert a protective anti-demineralizing effect on enamel that is not immediately adjacent to the restoration. Four experimental resin composites with bioactive glass and three commercial restorative materials were investigated. Enamel blocks were incubated in a lactic acid solution (pH = 4.0) at a standardized distance (5 mm) from cured specimens of restorative materials. The lactic acid solution was replenished every 4 days up to a total of 32 days. Surfaces of enamel blocks were periodically evaluated by Knoop microhardness measurements and scanning electron microscopy. The protective effect of restorative materials against acid was identified as enamel microhardness remaining unchanged for a certain number of 4-day acid addition cycles. Additionally, the pH of the immersion medium was measured. While enamel microhardness in the control group was maintained for 1 acid addition cycle (4 days), restorative materials postponed enamel softening for 2–5 cycles (8–20 days). The materials capable of exerting a stronger alkalizing effect provided longer-lasting enamel protection. The protective and alkalizing effects of experimental composites improved with higher amounts of bioactive glass and were better for conventional bioactive glass 45S5 compared to a fluoride-containing bioactive glass. Scanning electron micrographs evidenced the protective effect of restorative materials by showing a delayed appearance of an etching pattern on the enamel surface. A remotely-acting anti-demineralizing protective effect on enamel was identified in experimental composites functionalized with two types of bioactive glass, as well as in three commercial ion-releasing restorative materials. [ABSTRACT FROM AUTHOR]

This study investigated the effect of adding bioactive glass 45S5 (BG) of different particle sizes to dental composite on resin polymerization and shrinkage stress formation. Commercial flowable composite was mixed with either 15 wt% BG fillers (nanometric, micrometric, or hybrid BG) or inert barium glass. Real-time linear polymerization shrinkage and shrinkage stress were recorded, and the degree of conversion was measured using FTIR spectroscopy. The commercial (unmodified) composite developed significantly higher linear shrinkage and shrinkage stress than the groups with 15 wt% added inert or BG fillers. After adding inert barium glass, the composite showed significantly higher linear shrinkage than when micrometric BG was added. The addition of bioactive or inert glass fillers did not affect the degree of conversion. Shrinkage stress can be reduced by adding inert or bioactive fillers (nano- and/or microparticulate BG) without affecting monomer conversion. [ABSTRACT FROM AUTHOR]

The present study investigated the effectiveness of employing a patient simulator with an integrated visual feedback mechanism to improve the light-curing skills of dental students. A total of 44 third-year dental students were randomly divided into a control group (n = 22) and a training group (n = 22). Both groups light-cured a simulated restoration in tooth 27 in a patient simulator (MARC Patient Simulator, BlueLight Analytics, Halifax, Canada) by using the same curing device for 10 s. Delivered irradiances were recorded in real time by the built-in spectrophotometer. After measuring the baseline irradiances for both groups, the training group received detailed light-curing instructions and hands-on training with immediate visual feedback using the patient simulator. The irradiance of the training group was re-measured after the training. Both groups then attended a 26-day preclinical course, which involved placing 30 composite restorations. Upon completion of this course, the light-curing performance of both groups was re-assessed. The data were statistically analyzed using the Wilcoxon signed-rank test, Friedman's ANOVA, and the Mann-Whitney U-test at an overall level of significance of α = 0.05. At baseline, the control and the training group delivered statistically similar irradiances with similar data scattering. In the training group, data scattering was considerably reduced after the hands-on training with the patient simulator. After the 26-day preclinical course, the irradiance of the training group was significantly higher and considerably less scattered compared to the control group. In conclusion, training with the patient simulator improved the light-curing performance of the dental students, mainly by helping them to deliver light energy more consistently. [ABSTRACT FROM AUTHOR]

Rapid high-intensity light-curing of dental resin composites is attractive from a clinical standpoint due to the prospect of time-savings. This study compared the effect of high-intensity (3 s with 3,440 mW/cm2) and conventional (10 s with 1,340 mW/cm2) light-curing on micromechanical properties of conventional and bulk-fill resin composites, including two composites specifically designed for high-intensity curing. Composite specimens were prepared in clinically realistic layer thicknesses. Microhardness (MH) was measured on the top and bottom surfaces of composite specimens 24 h after light-curing (initial MH), and after subsequent immersion for 24 h in absolute ethanol (ethanol MH). Bottom/top ratio for initial MH was calculated as a measure of depth-dependent curing effectiveness, whereas ethanol/initial MH ratio was calculated as a measure of crosslinking density. High-intensity light-curing showed a complex material-dependent effect on micromechanical properties. Most of the sculptable composites showed no effect of the curing protocol on initial MH, whereas flowable composites showed 11–48% lower initial MH for high-intensity curing. Ethanol/initial MH ratios were improved by high-intensity curing in flowable composites (up to 30%) but diminished in sculptable composites (up to 15%). Due to its mixed effect on MH and crosslinking density in flowable composites, high-intensity curing should be used with caution in clinical work. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate margin integrity of Class V composite restorations in demineralized and sound enamel after bonding with different etch-and-rinse and self-etch adhesive systems. Out of a total of 60 specimens from bovine incisors, 30 specimens were demineralized (21 days, acid buffer, pH 4.95) to create artificial enamel lesions. Circular Class V cavities were prepared in all 60 specimens and treated with either an unfilled etch-and-rinse adhesive (Syntac Classic; Ivoclar Vivadent), a filled etch-and-rinse adhesive (Optibond FL; Kerr), or a self-etch adhesive (iBond Self Etch; Heraeus) (n = 10 per group). The cavities were restored with a nanofilled resin composite and thermocycled (5000×, 5–55 °C). Scanning electron microscopy was used to evaluate margin integrity of the composite restorations, and the percentage of continuous margin was statistically analyzed (α = 0.05). Demineralized enamel led to a significantly lower margin integrity when the self-etch adhesive iBond Self Etch was applied, but did not affect margin integrity when the etch-and-rinse adhesives Optibond FL (filled) or Syntac Classic (unfilled) were used. No significant differences in margin integrity in sound and demineralized enamel were observed between the different adhesives. Demineralized enamel reduces margin integrity of composite restorations when bonded with a self-etch adhesive, but does not affect margin integrity when an etch-and-rinse approach is used. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate polymerization shrinkage, shrinkage force development, and degree of monomer conversion of high- and low-viscosity dimethacrylate- and ormocer-based bulk-fill resin composites. Two flowable bulk-fill composites (SDR, x-tra base), two high-viscosity bulk-fill composites (Bulk Ormocer, SonicFill), and two conventional composite materials (Esthet X flow, Esthet X HD) were photoactivated for 20 s at 1275 mW/cm2. Linear polymerization shrinkage and shrinkage force were recorded in real time using custom-made devices, and the force rate and time to achieve maximum force rate were determined. Degree of conversion was measured using Fourier-transform infrared spectroscopy. Data were analyzed with one-way ANOVA and Tukey's HSD post-hoc test, and bivariate correlations were computed (α = 0.05). The category of high-viscosity bulk-fill resin composites showed the significantly lowest polymerization shrinkage and force development. Within the tested flowable composite materials, SDR bulk-fill generated the significantly lowest shrinkage forces during polymerization and attained the significantly highest degree of conversion. Strong positive correlations were revealed between shrinkage force and both linear polymerization shrinkage (r = 0.902) and maximum force rate (r = 0.701). Linear shrinkage and shrinkage force both showed a negative correlation with filler volume content (r = − 0.832 and r = − 0.704, respectively). Bulk-fill resin composites develop lower shrinkage forces than their conventional flowable and high-viscosity counterparts, respectively, which supports their use for restoring high C-factor posterior cavities. Overall, bulk-fill composites with high filler amount and low force rate showed the most favorable shrinkage force characteristics. [ABSTRACT FROM AUTHOR]

Objective. To investigate the subsurface degree of conversion (DC) and shrinkage force formation of low-viscosity (flowable) bulk-fill composite materials. Materials and methods. Three flowable bulk-fill resin composites [SureFil SDR flow (SDR; Dentsply DeTrey), Venus Bulk Fill (VB; Heraeus Kulzer) and x-tra base (XB; VOCO)] and one conventional flowable control composite material [EsthetX flow (EX; Dentsply DeTrey)] were tested. The materials were photoactivated for 20 s at an irradiance of 1170 mW/cm2 and the DC ( n = 5) was recorded at 0.1-, 1.5- and 4-mm depth using Fourier transform infrared spectroscopy. Shrinkage forces ( n = 5) of 1.5-mm-thick specimens were continuously recorded for 15 min using a custom-made stress analyzer. Data were statistically analyzed by ANOVA, Tukey's HSD and Bonferroni's post-hoc tests ( α = 0.05). Results. SDR generated the significantly lowest shrinkage forces (22.9 ± 1.4 N), but also attained the significantly lowest DC at 1.5-mm depth (67.5 ± 0.8%). The conventional flowable composite EX generated the significantly highest shrinkage forces (40.7 ± 0.7 N) and reached a significantly higher DC (74.4 ± 1.3%) compared to SDR and XB at 1.5-mm depth. The shrinkage force values of VB (29.4 ± 1.1 N) and XB (28.3 ± 0.6 N) were similar ( p > 0.05). All materials attained significantly higher DC at 4-mm depth than at the near-surface. Conclusion. The tested low-viscosity bulk-fill materials show lower shrinkage force formation than a conventional flowable resin composite at high levels of degree of conversion up to 4-mm incremental thickness. [ABSTRACT FROM AUTHOR]

This study investigated the influence of modulated photo-activation on axial polymerization shrinkage, shrinkage force, and hardening of light- and dual-curing resin-based composites. Three light-curing resin composites ( SDR bulk-fill, Esthet X flow, and Esthet X HD) and one dual-curing material ( Rebilda DC) were subjected to different irradiation protocols with identical energy density (27 J cm−2): high-intensity continuous light ( HIC), low-intensity continuous light ( LIC), soft-start ( SS), and pulse-delay curing ( PD). Axial shrinkage and shrinkage force of 1.5-mm-thick specimens were recorded in real time for 15 min using custom-made devices. Knoop hardness was determined at the end of the observation period. Statistical analysis revealed no significant differences among the curing protocols for both Knoop hardness and axial shrinkage, irrespective of the composite material. Pulse-delay curing generated the significantly lowest shrinkage forces within the three light-curing materials SDR bulk-fill, Esthet X flow, and Esthet X HD. High-intensity continuous light created the significantly highest shrinkage forces within Esthet X HD and Rebilda DC, and caused significantly higher forces than LIC within Esthet X flow. In conclusion, both the composite material and the applied curing protocol control shrinkage force formation. Pulse-delay curing decreases shrinkage forces compared with high-intensity continuous irradiation without affecting hardening and axial polymerization shrinkage. [ABSTRACT FROM AUTHOR]

Background Surface sealants have been successfully used in the prevention of erosive tooth wear. However, when multiple tooth surfaces should be sealed, the light-curing procedure is very time-consuming. Therefore, the aim of this study was to investigate whether reduced lightcuring time (while maintaining similar energy density) has an influence on resin-based surface sealant cytotoxicity. Methods Bovine dentine discs were treated as follows: group 1: untreated, groups 2-5: Seal&Protect and groups 6-9: experimental sealer. Groups 2 and 6 were light-cured (VALO LED lightcuring device) for 40 s (1000 mW/cm2), groups 3 and 7 for 10 s (1000 mW/cm2), groups 4 and 8 for 7 s (1400 mW/cm2) and groups 5 and 9 for 3 s (3200 mW/cm2). Later, materials were extracted in culture medium for 24 h, and released lactate dehydrogenase (LDH) activity as a measure of cytotoxicity was determined photometrically after cells (dental pulp cells and gingival fibroblasts) were exposed to the extracts for 24 h. Three independent experiments, for both sample preparation and cytotoxicity testing, were performed. Results Overall, lowest cytotoxicity was observed for the unsealed control group. No significant influence of light-curing settings on the cytotoxicity was observed (p = 0.537 and 0.838 for pulp cells and gingival fibroblasts, respectively). No significant difference in the cytotoxicity of the two sealants was observed after light-curing with same light-curing settings (group 2 vs. 6, 3 vs. 7, 4 vs. 8 and 5 vs. 9: p > 0.05, respectively). Conclusions Shortening the light-curing time, while maintaining constant energy density, resulted in no higher cytotoxicity of the investigated sealants. [ABSTRACT FROM AUTHOR]

Objective. To test the durability of sealants applied for prevention of erosive dentine mineral loss under erosive/abrasive conditions. Methods. Forty-eight bovine dentine samples doped with 32P were randomly allocated to four groups (1-4). All samples performed a de- and remineralizations pre-cycling (6 × 1 min erosion in HCl: pH 3.0, mean time and overnight immersion in artificial saliva) for 1 day. Sealing was done as follows; (1) unsealed, (2) Seal & Protect, (3) K-0184 (experimental sealer) and (4) OptiBond FL. After sealing, samples were immersed in HCl for 3 h (baseline measurement). Then, the following erosive/abrasive and remineralisations cycling was performed for 8 days: 3 h/day erosion with HCl, 600 brushing strokes/day and storage in artificial saliva for the rest of the day. Sealer permeability was evaluated by assignation of 32P in the acid used for the erosive attacks. Results. At baseline, the significantly highest dentine loss was observed for the unsealed control group, while the mineral loss was not statistically significantly different between the sealed groups 2 and 3. At all days of the erosive/abrasive and remineralizations cycling and cumulatively the significantly highest mineral loss was observed for group 1, while the significantly lowest mineral loss was observed for the samples sealed with Seal & Protect (group 2) and K-0184 (group 3). In all groups, no significant increase in the 32P release was observed. Conclusion. Surface sealants are able to reduce the erosive dentine mineral loss and maintain this erosion-preventing efficacy over the whole duration (simulating 8 month in-vivo) of the erosive/abrasive cycling. [ABSTRACT FROM AUTHOR]

Objective. To investigate the abrasive wear of surface sealants (Seal&Protect and K-0184 (experimental sealant)) and the influence of pre-treatment with mineral deposit forming prophylaxis pastes (NUPRO Sensodyne and NUPRO) on this wear. Methods. One hundred and eight bovine dentine samples were randomly allocated to nine groups (1-9). Pre-treatment (10 s): groups 1-3: untreated, groups 4-6: NUPRO, groups 7-9: NUPRO Sensodyne. Sealing: groups 1, 4 and 7: unsealed, groups 2, 5 and 8: Seal&Protect, groups 3, 6 and 9: K-0184 (experimental sealer). Samples were then brushed with 12 000 brushing strokes (BS) with toothpaste slurry in an automatic brushing machine (120 BS/min; F = 2.5 N). Surface profiles were recorded at baseline, after pre-treatment and sealing and after each 2000 BS. Results. Total profile change (wear or gain due to pre-treatment, treatment and 12 000 BS): groups 1, 4 and 7 (no surface sealant) showed a not significantly different wear of 18.48 ± 2.63 µm, 24.98 ± 3.02 µm and 21.50 ± 5.47 µm, respectively. Remaining groups (sealed) showed a gain in height with no significant difference among each other. Wear in sealed groups (2, 3, 5, 6, 8 and 9) were not significantly different at all numbers of brushing strokes. Starting with 4000 BS, the wear in unsealed groups (1, 4 and 7) was statistically significantly higher compared to all other groups. Conclusion. Stability and wear resistance of surface sealants are not affected by pre-treatment of dentine with NUPRO Sensodyne. The surface sealants tested provide a stable protective surface layer on dentine, which lasts for at least 12 000 brushing strokes. [ABSTRACT FROM AUTHOR]

Background. The authors conducted an in vitro study to investigate the influence of several internal bleaching regimens on the composite-to- composite shear bond strength of a dental core buildup material. Methods. The authors fabricated 72 specimens from a resin-based composite core buildup and assigned them randomly to six groups (four experimental and two control groups) (n = 12 per group), according to the following bleaching agents: sodium perborate mixed with distilled water (SP/W); sodium perborate mixed with 3 percent hydrogen peroxide (SP/HP-3); sodium perborate mixed with 30 percent hydrogen peroxide (SP/HP-30); 35 percent ' hydrogen peroxide (HP-35). After the 12-day bleaching procedures, the authors applied a calcium hydroxide dressing for two weeks. The two control groups consisted of unbleached specimens that either did not receive (Cl) or did receive (C2) the calcium hydroxide dressing. The authors cleaned and silanized the resin-based composite specimens and coated them with an intermediate adhesive resin before applying fresh composite material. They measured composite surface roughness and shear bond strength and performed statistical analyses of the data. Results. Unbleached specimens in groups Cl and C2 exhibited significantly lower composite-to-composite bond strength and significantly lower surface roughness than did specimens in groups SP/W and SP/HP-3. Bond strength in group HP-35 was significantly lower than that in group SP/W. Conclusion. Internal bleaching regimens that involve the use of sodium perborate mixed with water or 3 percent hydrogen peroxide might increase the composite-to-composite interfacial bond strength. Clinical Implications. None of the internal bleaching regimens in this study had an adverse effect on the composite-to-composite interfacial bond strength. [ABSTRACT FROM AUTHOR]

Objective. Application of SnCl2/AmF/NaF containing mouth rinse showed good protection against erosion. The aim of the study was to evaluate if this is due to the amount of KOH-soluble fluoride (KOHsF) formed or its resistance under erosive conditions. Methods. One hundred and fifty bovine enamel samples were allocated to five groups (n = 30) and were once eroded in 0.05 mol/l citric acid (5 min). Samples were stored in artificial saliva for 4 days. Samples of two groups (erosive-SnCl2 + erosive-NaF) were eroded 6 × for 5 min. The remaining samples were stored in aqua dest deionised water. Each day the samples were treated twice for 2 min with 1 ml SnCl2/AmF/NaF-solution (erosive-SnCl2;neutral-SnCl2/AmF/NaF) or NaF-solution (erosive-NaF;neutral-NaF). The fifth group remained untreated (control). On day 5, 10 samples of each group were used for determination of KOHsF (series 1). The remaining samples were again eroded (erosive-SnCl2 + erosive-NaF) or stored in artificial saliva (neutral-SnCl2 + neutral-NaF). KOHsF of another 10 samples of each group was measured (series 2). The last 10 samples of each group were also treated as described above and the amount of KOHsF was measured (series 3). Results. In each series 1-3 KOHsF in group erosive-SnCl2/AmF/NaF were significantly higher. No significant loss of KOHsF between the series 1-3 was observed (except for control). Conclusion. SnCl2/AmF/NaF containing mouth rinse revealed a better formation of KOH-soluble fluoride as the NaF-solution, although the applied fluoride compound has no influence on the stability of the KOHsF under erosive conditions, leading to the conclusion that the resistance of KOHsF is not responsible for the difference in the protection against dental erosion. [ABSTRACT FROM AUTHOR]

Objective. The purpose of the present survey was to evaluate the implementation and experience of a new method for posterior vertical bite reconstruction using direct resin composite restorations by private practitioners who attended a hands-on continuing education course on this technique. Materials and methods. In the years 2007 and 2008, 17 1-day continuing education courses on vertical bite reconstruction in the worn dentition by using direct resin composite restorations were attended by 310 participants. A 13-item questionnaire was posted to all course participants in April 2009 seeking information on the acceptance, implementation and experience of the presented technique in the private practice. Results. A total of 97 (31%) questionnaires were returned, whereas 67% of the respondents had used the presented technique. Analysis of the overall experience and satisfaction with the placed resin composite restorations using visual analog scale (VAS) revealed a mean VAS score of 7.2 ± 1.7 (0 = maximal unsatisfied, 10 = maximal satisfied). The direct resin composite restorations were predominantly rated 'good' within the assessed criteria surface texture, anatomical form, marginal integrity, marginal discoloration and color match. Ninety-eight percent of the private practitioners stated that they would continue to carry out vertical bite reconstructions according to this technique. The three most frequently observed clinical problems were related to marginal discolorations, bulk fractures and adhesive failures. Conclusion. The presented restoration method was well accepted by private practitioners who used this treatment approach at least once after course participation, even though some clinical problems were observed. [ABSTRACT FROM AUTHOR]

Objectives. This in-situ study aimed to investigate the potential of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) crème and fluoride mouth rinse to re-harden erosively softened enamel and to evaluate the influence of an intra-oral or extra-oral application. Methods. Ten volunteers performed five experimental series. Per series, four bovine enamel samples were extra-orally softened by immersion in Sprite light® (2 min) and subsequently worn intra-orally for 5 min in intra-oral appliances. Thereafter, samples were treated (3 min) with either 250 ppm AmF/SnF2 solution (Meridol) (series 1 and 3) or CPP-ACP crème (Tooth Mousse) (series 2 and 4). Application of the substances was performed extra-orally (series 1 and 2) or intra-orally (series 3 and 4). Untreated specimens served as control (series 5). The appliances were worn for 4 h afterwards. Knoop microhardness (KHN) measurement was performed at baseline, after softening and after completing of the respective run. Data were statistically analyzed by ANOVA and Bonferroni/Dunn post-hoc test. Results. No significant difference in baseline microhardness was observed, while immersion in Sprite light reduced the microhardness significantly. Significant re-hardening after intra-oral exposure occurred in all series, but baseline microhardness was not achieved. Microhardness in series 2 was significantly higher than that in series 1 and 5. No significant differences in KHN were detected between series 3, 4 and 5. The re-hardening ΔKHN (final microhardness - microhardness after erosion) was not significant different in all five series. Conclusion. Intra-oral application of CPP-ACP crème or fluoride solution provides no benefit regarding re-hardening of erosively softened enamel. [ABSTRACT FROM AUTHOR]

Objectives. To investigate if reducing the light-curing time (while maintaining similar energy density) of resin-based surface sealants influences their erosion-preventive potential and mechanical stability after thermo mechanical loading. Methods. Dentine samples were treated as follows: group 1-untreated, groups 2-4-Seal&Protect, groups 5-7-experimental sealer, and groups 8-10- Syntac Classic system. Groups 2, 5 and 8 were light-cured for 10 s (1000 mW/cm2), groups 3, 6 and 9 for 7 s (1400 mW/cm2), and groups 4, 7, and 10 for 3 s (3200 mW/cm2). After water storage (7 d), first measurement was performed to evaluate baseline permeability of the sealants. After a thermo mechanical loading (5000 cycles, 50/5°C, 12000 brushing strokes) a second evaluation of permeability was conducted (measurement 2). Permeability was tested by storing the samples in HCl (pH 2.3; 24 h) and measuring the dentine calcium release by atomic absorption spectroscopy. Results. For the first and second measurements, no influence of light-exposure time on permeability was observed (ANOVA: P > 0.05). No significant difference in the stability of the respective sealants was observed when light-cured for different durations. Conclusion. Shortening the light-curing time, while maintaining energy density constant, has no influence on permeability and stability of the investigated sealants. [ABSTRACT FROM AUTHOR]

The article focuses on the study regarding the comparison of light curing and self-curing in the dual-cured core buildup material polymerization. The study employed resin-based dual-cured core buildup filled molds with self-cured materials as controls, which are tested for Knoop hardness number (KHN). Results show that the photoactivation of the dual-cured materials has no relevant benefit compared with self-curing materials in relation to microhardness.

Objective. To investigate the influence of time delay and duration of photo-activation on subsurface microhardness of a dual-cured resin composite. Material and methods . A commercially available dual-cured core build-up resin composite (Rebilda DC) was filled in cavities (diameter: 4.0 mm; height: 6.0 mm) of polystyrene molds and light-cured for 20 or 60 s either immediately after the filling procedure (time delay 0 s) or after a time delay of 30, 90, 180 or 300 s. Non-irradiated self-cured specimens served as a control group ( n = 15). Specimens were stored in complete darkness and at 100% relative humidity at 37°C for 2 weeks and cross-sectioned. Knoop Hardness Numbers (KHNs) were measured six times per depth and averaged at distances of 0.25, 0.50, 1.00, 2.00, 3.50 and 5.50 mm from the light-exposed surface. Data were statistically analyzed using one- and two-way ANOVA followed by Scheffé's post-hoc test at a level of significance of 0.05. Results . Mean hardness values in all experimental groups ranged between 54.3 ± 2.1 and 58.1 ± 2.3 KHN. Light-curing did not significantly increase composite KHN at any depth measured. Delaying light exposure had no influence on KHN, irrespective of depth. A longer light-exposure time (60 versus 20 s) resulted in significantly higher KHN only at depths of 3.50 and 5.50 mm. Conclusion. Photo-activation of the tested dual-cured resin composite provided no clinically relevant benefit compared to self-curing regarding the degree of hardening. [ABSTRACT FROM AUTHOR]

Tauböck TT, Bortolotto T, Buchalla W, Attin T, Krejci I. Influence of light-curing protocols on polymerization shrinkage and shrinkage force of a dual-cured core build-up resin composite. Eur J Oral Sci 2010; 118: 423–429. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci This study investigated the influence of time delay and duration of photo-activation on linear polymerization shrinkage, shrinkage force, and hardening of a dual-cured core build-up resin composite. The test material (Rebilda DC) was light-cured for 20 or 60 s either early (2 min) or late (7 min) after the start of mixing. Non-irradiated self-cured specimens served as controls. Linear shrinkage and shrinkage force were measured for 60 min using custom-made devices. Knoop hardness was determined at the end of the observation period. Self-cured controls, showing a linear shrinkage similar to that of specimens early light-cured for 20 s generated the lowest shrinkage force and hardness. A shorter light exposure time (20 s vs. 60 s) reduced linear shrinkage, shrinkage force, and hardness when early light-curing was performed, but did not affect the three properties in specimens light-cured late after the start of mixing. Late photo-activation increased linear shrinkage, irrespective of irradiation time, and resulted in a higher shrinkage force and hardness for short light exposure time. A moderate correlation was found between the two shrinkage properties studied ( r2 = 0.65). In conclusion, improvements in shrinkage behavior of the tested core build-up material were associated with inferior hardening, making it important to adapt curing protocols to the clinical situation. [ABSTRACT FROM AUTHOR]

The purpose of this in vitro study was to investigate whether different types of experimental and commercial restorative dental materials can protect dentin against acid-induced softening. Experimental composites were prepared with a photocurable mixture of methacrylates and two types of bioactive glass (45S5 and a customized low-Na F-containing formulation). Human dentin samples were prepared from mid-coronal tooth slices and immersed in lactic acid solution (pH = 4.0) at 5 mm from set specimens of restorative material. After 4, 8, 12, 16, 20, 24, 28, and 32 days, surface microhardness of dentin samples and pH of the immersion solution were measured, followed by replenishing of the immersion medium. Microstructural analysis was performed using scanning electron microscopy. The protective effect of restorative materials was determined as dentin microhardness remaining statistically similar to initial values for a certain number of acid additions. Scanning electron microscopy showed a gradual widening of dentinal tubules and proved less discriminatory than microhardness measurements. To produce a protective effect on dentin, 20 wt% of low-Na F-containing bioactive glass was needed, whereas 10 wt% of bioactive glass 45S5 was sufficient to protect dentin against acid-induced demineralization. The anti-demineralizing protective effect of experimental and commercial restoratives on dentin was of shorter duration than measured for enamel in a previous study using the same experimental approach. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of individual instructions and training of dental students on the amount of applied light irradiance before and after training using a patient simulator with integrated visual feedback. Furthermore, the effect on the degree of conversion of composite restorations placed by the dental students was assessed. Forty-two dental students, split into two groups, light-cured a simulated restoration in tooth 27 of a dental patient simulator for 20 s. The irradiance (mW/cm2) received by the detector was measured in real-time before and after individual instructions and training, and the energy delivered (J/cm2) was calculated for each student. The degree of conversion at the bottom of incrementally placed composite restorations prior to individual instructions (group 1) and after individual instructions (group 2) was assessed using Fourier-transform infrared (FTIR) spectroscopy. The irradiance and degree of conversion measurements were re-assessed after all students received individual instructions. Data were analyzed using Wilcoxon signed-rank test and Mann-Whitney U-test at an overall level of significance of α = 0.05. A significant increase (p < 0.001) in applied light irradiance could be observed after individual instructions for both groups, with notably reduced data scattering. However, no significant difference was detected for the degree of conversion of placed composite restorations before or after instruction and training. Neither gender nor age of the dental students affected the obtained results. Consistent light energy delivered by dental students could be achieved through individual instructions and training with a patient simulator, also leading to less scattered irradiance results. However, the improved light-curing performance after the training did not affect the degree of conversion of the placed class II composite restorations. [ABSTRACT FROM AUTHOR]

This study investigated the short- and long-term effects of dental adhesives doped with nano-sized bioactive glass 45S5 (BAG) on the resin–dentin interfacial bond strength. Two etch-and-rinse adhesives (Adper Scotchbond Multi-Purpose (ASB) and Solobond Plus (SB)) and one self-etch adhesive (Clearfil SE Bond (CF)) were doped with different concentrations of BAG (5, 10, and 20 wt%). The unmodified (0 wt% BAG) commercial adhesives served as control groups. Dentin of 120 molars (n = 10 per group) was treated with the different adhesives, followed by buildups with a conventional composite restorative material. From each tooth, 14 sticks were prepared for micro-tensile bond strength (µTBS) testing. The sticks were stored in simulated body fluid at 37 °C and tested after 24 h or six months for µTBS and failure mode. Data were analyzed using Kruskal–Wallis tests in combination with post-hoc Conover-tests and Wilcoxon signed-rank tests at a level of significance of α = 0.05. After 24 h and six months, both etch-and-rinse adhesives with a low BAG content (up to 10 wt% for ASB and 5 wt% for SB) showed similar µTBSs as their respective control groups (0 wt% BAG). CF showed a significant decrease in µTBS even after addition of 5 wt% BAG. At a high concentration of added BAG (20 wt%), all three adhesives showed a significant decrease in µTBS compared to the unmodified controls. The CF control group showed significantly lower µTBS after 6 months of storage than after 24 h. In contrast, the µTBS of all CF groups modified with BAG was unaffected by aging. In conclusion, the tested etch-and-rinse adhesives can be modified with up to 5 wt% (SB), or 10 wt% (ASB) of BAG without reducing their short- and long-term dentin bond strength. Moreover, the addition of nano-sized BAG may prevent long-term bond strength deterioration of a self-etch adhesive. [ABSTRACT FROM AUTHOR]

Our aim was to evaluate the clinical performance of direct composite restorations placed in patients with severely worn dentitions at an increased vertical dimension of occlusion, after up to 11 years. One hundred and sixty-four teeth in 13 patients with severely worn dentitions had been reconstructed with either microhybrid (first cohort; n = 59) or nanofilled (second cohort; n = 105) composite restorations at increased vertical dimension of occlusion using a wax-up-based template-aided placement technique. From the dental records, information about repair and replacement of restorations was obtained. Patients were clinically examined after a mean follow-up time of 10.7 years (first cohort) or 5.2 years (second cohort) using United States Public Health Service (USPHS) criteria. Subjective patient satisfaction was also recorded using visual analogue scales (VAS). The overall quality of the restorations was good with predominantly 'Alpha' and 'Bravo' scores, respectively. Nanofilled composite showed less surface degradation and better margin qualities than microhybrid composite. Of the 59 restored teeth in the first cohort, 13 restorations showed unfavorable events after 10.7 years, of which ten could be repaired. In the second cohort, 23 of 105 restorations showed unfavorable events, which could all be repaired. VAS scores revealed high patient satisfaction with the treatment approach. In conclusion, direct composite restorations placed at an increased vertical dimension of occlusion show good clinical long-term performance in patients with severe tooth wear. [ABSTRACT FROM AUTHOR]

This study investigates the effect of defined working distances between the tip of a sandblasting device and a resin composite surface on the composite–composite repair bond strength. Resin composite specimens (Ceram.x Spectra ST (HV); Dentsply Sirona, Konstanz, Germany) were aged by thermal cycling (5000 cycles, 5–55 °C) and one week of water storage. Mechanical surface conditioning of the substrate surfaces was performed by sandblasting with aluminum oxide particles (50 µm, 3 bar, 10 s) from varying working distances of 1, 5, 10, and 15 mm. Specimens were then silanized and restored by application of an adhesive system and repair composite material (Ceram.x Spectra ST (HV)). In the negative control group, no mechanical surface pretreatment or silanization was performed. Directly applied inherent increments served as the positive control group (n = 8). After thermal cycling of all groups, microtensile repair bond strength was assessed, and surfaces were additionally characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The negative control group reached the significantly lowest microtensile bond strength of all groups. No significant differences in repair bond strength were observed within the groups with varying sandblasting distances. Composite surfaces sandblasted from a distance of 1 mm or 5 mm showed no difference in repair bond strength compared to the positive control group, whereas distances of 10 or 15 mm revealed significantly higher repair bond strengths than the inherent incremental bond strength (positive control group). In conclusion, all sandblasted test groups achieved similar or higher repair bond strength than the inherent incremental bond strength, indicating that irrespective of the employed working distance between the sandblasting device and the composite substrate surface, repair restorations can be successfully performed. [ABSTRACT FROM AUTHOR]

This study investigated the effect of over-etching and prolonged application time of a universal adhesive on dentin bond strength. Ninety extracted human molars were ground to dentin and randomly allocated into nine groups (G1–9; n = 10 per group), according to the following acid etching and adhesive application times. In the control group (G1), phosphoric acid etching was performed for 15 s followed by application of the universal adhesive Scotchbond Universal (3M) for 20 s, as per manufacturer's instructions. In groups G2–5, both the etching and adhesive application times were either halved, doubled, quadrupled, or increased eightfold. In groups G6–9, etching times remained the same as in G2–5 (7.5 s, 30 s, 60 s, and 120 s, respectively), but the adhesive application time was set at 20 s as in the control group (G1). Specimens were then restored with a nanofilled composite material and subjected to microtensile bond strength testing. Bond strength data were statistically analyzed by ANOVA and Tukey's post-hoc tests (α = 0.05). The relationship of bond strength with etching and adhesive application time was examined using linear regression analysis. Treatment of dentin with halved phosphoric acid etching and adhesive application times (G2) resulted in a significant bond strength decrease compared to the control group (G1) and all other test groups, including the group with halved acid etching, but 20 s of adhesive application time (G6). No significant differences in bond strength were found for groups with multiplied etching times and an adhesive application time of 20 s or more, when compared to the control group (G1). In conclusion, a universal adhesive application time of at least 20 s is recommended when bonding to over-etched dentin. [ABSTRACT FROM AUTHOR]