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Abstract Background This clinical study was conducted aiming to evaluate the impact of repeated preheating of bulk-fill resin composite on postoperative hypersensitivity. Methods A total of 105 eligible, consenting adults were recruited. Patients had posterior teeth suffering from proximal decay with no signs of irreversible pulpitis. Patients were prepared for Class II restorations and restored with bulk-fill resin composite. Patients were randomized into three groups of 35 patients according to the number of preheating cycles for the resin composite syringe used; group I: no preheating; control group at room temperature, group II: Resin composite preheated once, and group III: Resin composite preheated ten cycles. Patients were assessed for postoperative dentin hypersensitivity using the visual analogue scale (VAS) at three-time intervals: day one, one week and by the end of one month after restorative treatment. Statistical analysis was performed; ANOVA with a single factor was used to test for significance at a p value ≤ 0.05. For nonparametric data, the Kruskal‒Wallis test was used to compare the three testing groups. Friedman’s test was used to study the changes within each group. Dunn’s test was used for pairwise comparisons when the Kruskal‒Wallis test or Friedman’s test was significant. Results The scores of the three groups through the three time intervals were almost zero except for the first day where VAS scores were recorded with maximum score of 3 for groups I and II. Groups II and III; there was no statistically significant change in hypersensitivity scores by time with P-values 0.135 and 0.368, respectively. However, for group I there was a significant difference from VAS score recorded on first day and the two following time intervals. Conclusion The repeated preheating cycles of bulk-fill resin composite prior to curing had no adverse effect on the patients regarding postoperative dentin hypersensitivity. This information could be of utmost significance, as the same resin composite syringe can undergo numerous preheating cycles clinically before it is completely consumed with the advantage of improvement on the handling properties. Trial registration The protocol of the current study was registered at www.clinicaltrials.gov , with the identification number NCT05289479 on 21/03/2022. All procedures involving human participants were performed in accordance with the ethical standards of the Research Ethics Committee of the Faculty of Dentistry, Minia University, Egypt, under the approval number 73/440 on 11/09/2020.

INTRODUCTION: Polymerization reactions in a new generation bulk-fill composites carried out in a short time with high irradiation, raise concerns about curing processes. With micro-computed tomographic evaluation, it is possible to investigate polymerization shrinkage, and subsequent gap and void formation in dental materials. OBJECTIVES: The aim of this study was to evaluate the void formation in bulk-fill composites light-cured with different modes using micro-computed tomography. MATERIAL AND METHODS: Class I preparations were made in 25 molars that were randomly divided into subgroups, according to resin composite and curing mode used: Tetric EvoCeram (TEC)*high power mode, TEC*turbo mode, Tetric PowerFill (TPF)*high power mode, TPF*turbo mode, and TPF*3s mode. Each tooth was scanned at two time intervals: pre- and post-cure. RESULTS: After light-curing, a significant increase in the total volume of internal void was noted for both composites cured with high power mode compared with pre-cure. The difference between the sub-groups at post-cure was also significant. While TEC exhibited similar values in terms of different curing modes, turbo and 3s modes caused a significant difference in TPF group, and the lowest void percentage was detected in 3s mode. CONCLUSIONS: Internal void formation results from an interplay of different factors, including composition of materials and curing modes. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to compare the clinical performance of dual- and light-cure bulk-fill resin composites (BFRCs) in Class ӀӀ restorations after 2 years. Materials and methods: A double-blinded, prospective, randomized clinical trial (RCT) was conducted following the CONSORT (Consolidated Standard of Reporting Trials) guidelines. Forty patients were enrolled in the study. Each patient received three compound Class ӀӀ restorations. One dual-cure (Fill-Up; Coltene Waledent AG) and two light-cure (QuiXfil; Dentsply, and Tetric N-Ceram Bulk Fill; Ivoclar Vivadent) BFRCs were used for 120 Class ӀӀ restorations. A universal adhesive (ONE COAT 7 UNIVERSAL; Coltene Waledent AG) was used with all restorations. Restorations were clinically evaluated after 1 week (baseline), 6 months, 12 months, 18 months, and finally after 24 months using the FDI World Dental Federation (FDI) criteria. The Kruskal–Wallis test was used for comparison between BFRCs groups at baseline and at each recall period, and the Wilcoxon signed-rank test was used for comparing different follow-up times of each BFRC to baseline. The level of significance was set at p < 0.05. Results: All BFRCs restorations showed only minor changes and revealed no statistically significant differences between their clinical performance for all evaluated parameters at all recall periods; also, there was no statistically significant difference between all recall periods and baseline for all evaluated parameters. Conclusion: The two-year clinical performance of dual-cure BFRC was comparable to light-cure BFRCs in Class ӀӀ restorations. Clinical relevance: Dual- and light-cure BFRCs showed excellent clinical performance in Class ӀӀ restorations after a 2-year clinical follow-up. [ABSTRACT FROM AUTHOR]

ABSTRACT: Objective: The aim of this research was to investigate the effect of various mouthwashes for COVID-19 prevention on surface hardness, roughness, and colour changes of bulk-fill and conventional resin composites and determine the pH and titratable acidity of mouthwashes. Methods: Four hundred eighty specimens were fabricated in cylindrical moulds (10 mm in diameter and 2 mm in thickness). Before immersion, baseline data of surface hardness, roughness, and colour values were recorded. Each product of specimens (Filtek Z350XT, Premise, Filtek One Bulk Fill Restorative, SonicFil 2) were divided into 4 groups for 0.2% povidone iodine, 1% hydrogen peroxide, 0.12% chlorhexidine, and deionised water (serving as a control). The specimens were immersed in mouthwashes for 1 minute and then stored in artificial saliva until 24 hours. This process was repeated for 14 days. After immersion, surface hardness, roughness, and colour values of specimens were measured at 7 and 14 days. The data were statistically analysed by 2-way repeated analysis of variance, Tukey honestly significant difference, and t test (P < .05). Results: After immersion, all mouthwashes caused significantly lower surface hardness and greater roughness and colour values (P < .05) on all resin composites tested. Conclusions: Mouthwashes had an effect on all resin composites evaluated leading to a significant decreased surface hardness and an increased roughness and colour values (P < .05).

Objective: To evaluate the effect of delayed light‐curing of dual‐cure bulk‐fill composites on internal adaptation and microhardness (KHN) in depth. Materials and Methods: Bulk‐fill composites were placed in 35 box‐shaped preparations and cured according to the following protocols (n = 5): Filtek Bulk‐Fill light‐cured immediately after insertion (FBF); Bulk‐EZ light‐cured immediately after insertion (BEZ‐I); Bulk‐EZ light‐cured 90 s after insertion (BEZ‐DP); Bulk‐EZ self‐cured (BEZ‐SC); HyperFIL light‐cured immediately after insertion (HF‐I); HyperFIL light‐cured 90 s after insertion (HF‐DP); HyperFIL self‐cured (HF‐SC). After 24 h, the samples were axially sectioned, and the internal adaptation was evaluated using replicas under a scanning electron microscope. The KHN was evaluated at six depths (0.3 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm). The statistical analysis was performed using α = 0.05. Results: The KHN significantly decreased with depth, except in self‐curing mode, when it was similar at all depths. Delayed light‐curing significantly increased the KHN at higher depths. The internal adaptation was material‐dependent. Light‐curing did not influence the internal adaptation of HyperFIL, whereas delayed light‐curing significantly reduced the internal gaps (%) of Bulk‐EZ. Conclusion: Delayed light‐curing improved the depth of cure of dual‐cure resin composites. Light‐curing did not influence the internal adaptation of HyperFIL, but delayed light‐curing improved the internal adaptation of Bulk‐EZ. Clinical Significance: Light‐curing is fundamental for improving the mechanical properties of dual‐cure resin composites. Moreover, depending on the dual‐cure resin composite, the delay in light‐curing can reduce the internal gaps. [ABSTRACT FROM AUTHOR]

Aims: This paper provides a thorough overview on the debonding problem and gap formation at pulpal floors in deep occlusal cavities restored directly with bulk-fill resin composites. It also reviews the techniques currently available in the literature for reducing this problem. Introduction: When a single mass of bulk-fill resin composite is inserted in a deep occlusal cavity and light cured, it undergoes restrained shrinkage due to bonding to surrounding cavity walls. This shrinkage generates stresses within the mass which are not uniformly distributed due to variations in adhesive bonding to enamel and dentin of surrounding cavity walls. This behavior creates a problem of internal debonding and gap formation at the pulpal floor that results in postoperative sensitivity and persistent tooth pain, as well as failure of the restoration, over the time, due to biodegradation of resin-dentin bond. Materials and Methods: The data was searched and collected from 2021-2022. A total of 51 articles were included in this review. Results and Discussion: Three restorative techniques were recently reported as possible solutions for this problem, all aiming at relieving the developed shrinkage stresses and reducing the pulpal floor gap formation. In the first technique, an intermediate layer of bulk-fill resin composite was placed on the pulpal floor and cured. While in the second technique, a fiber-reinforced layer of bulk-fill resin composite was placed on the pulpal floor and cured. In these two techniques, the restoration was completed by filling the cavity with a mass of bulk-fill resin composite and curing it. As for the third technique “the semi-split bulk-filling technique”, a diagonal gap was cut in the uncured mass of bulk-fill resin composite, extending halfway in pulpal direction through the composite bulk, followed by curing. Then, the created gap was filled with the same bulk-fill resin composite to complete the restoration and followed by curing. Conclusion: The three restorative techniques reported in this paper are possible solutions to the problem of debonding and gap formation at pulpal floors in deep occlusal cavities restored directly using bulk-fill resin composites. They all relieve the developed shrinkage stresses and reduce the pulpal floor gap formation.

Abstract Background Proper isolation and restoration of class V subgingival cavities are technique sensitive, thus the resin composite restoration is liable to contamination. This in vitro study was conducted to evaluate the surface microhardness and compressive strength of bulk-fill flowable resin composite after being contaminated during its packing. Methods Resin composite discs were prepared using split mold. The contaminated specimens were allocated into four groups (n = 20) according to the contaminant used: hemostatic agent (Group 1), alcohol (Group 2), artificial saliva (Group 3) and powdered gloves (Group 4). The non-contaminated specimens (n = 20) were used as control group. The surface microhardness and compressive strength of each group were tested 1-day post-photocuring (n = 5) and 1 month post-photocuring (n = 5). Values were presented as mean, standard deviation values and confidence intervals. Results The surface microhardness of all groups didn’t show a significant difference for different tested groups except for alcohol which showed a significant reduction on surface microhardness compared to control at 1 day post-photocuring (p = 0.001). The highest compressive strength mean values at 1 day and 1 month post-photocuring were recorded in control groups (110.42 MPa and 172.87 MPa respectively), followed by alcohol groups, then hemostatic agent groups, followed by artificial saliva with the least value recorded in powdered gloves groups (56.71 MPa and 49.5 MPa respectively). Conclusions Contamination of bulk-fill flowable resin composite with hemostatic agent, alcohol, artificial saliva, or powdered gloves during its packing decreased its compressive strength after 1 month post-photocuring rather than affecting its surface microhardness.

Aims: This paper provides a thorough overview on the debonding problem and gap formation at pulpal floors in deep occlusal cavities restored directly with bulk-fill resin composites. It also reviews the techniques currently available in the literature for reducing this problem. Introduction: When a single mass of bulk-fill resin composite is inserted in a deep occlusal cavity and light cured, it undergoes restrained shrinkage due to bonding to surrounding cavity walls. This shrinkage generates stresses within the mass which are not uniformly distributed due to variations in adhesive bonding to enamel and dentin of surrounding cavity walls. This behavior creates a problem of internal debonding and gap formation at the pulpal floor that results in postoperative sensitivity and persistent tooth pain, as well as failure of the restoration, over the time, due to biodegradation of resin-dentin bond. Materials and Methods: The data was searched and collected from 2021-2022. A total of 51 articles were included in this review. Results and Discussion: Three restorative techniques were recently reported as possible solutions for this problem, all aiming at relieving the developed shrinkage stresses and reducing the pulpal floor gap formation. In the first technique, an intermediate layer of bulk-fill resin composite was placed on the pulpal floor and cured. While in the second technique, a fiber-reinforced layer of bulk-fill resin composite was placed on the pulpal floor and cured. In these two techniques, the restoration was completed by filling the cavity with a mass of bulk-fill resin composite and curing it. As for the third technique "the semi-split bulk-filling technique", a diagonal gap was cut in the uncured mass of bulk-fill resin composite, extending halfway in pulpal direction through the composite bulk, followed by curing. Then, the created gap was filled with the same bulk-fill resin composite to complete the restoration and followed by curing. Conclusion: The three restorative techniques reported in this paper are possible solutions to the problem of debonding and gap formation at pulpal floors in deep occlusal cavities restored directly using bulk-fill resin composites. They all relieve the developed shrinkage stresses and reduce the pulpal floor gap formation. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate the effect of different aging methods on repair bond strength of different types of composite resins. Materials and Methods: Thirty resin composite blocks (5mm×5mm×4mm) were built up with a nanohybrid universal resin composite and a bulk-fill resin composite according to the manufacturer’s instructions, using a silicone matrix. Indirect resin composite blocks were obtained with similar dimensions from prefabricated blocks by microtome. All the samples were air abraded with 50µm aluminum oxide particles. Specimens were then repaired with a nanohybrid resin composite using two step adhesive system. All these specimens were then randomly divided into three groups for aging process (pH cycle, thermal cycle and control group) and tested for shear bond strength. Results were recorded in MPa. Additionally fractured specimens were examined under stereomicroscope to determine the mode of failure. The data was statistically analyzed using two-way ANOVA and Bonferroni correction test (p lt;0,05). Results: Statistically significant effect was found on the bond strength values of the aging method and the restorative material (p lt;0,05). Thermal cycle applied samples showed statistically significantly lower bond strength values than both pH cycle and control group samples (p lt;0,05). Regardless of the aging method, the overall bond strength of Tetric N-Ceram Bulk Fill is statistically significantly higher than bond strength of Tetric CAD (p lt;0,05). Conclusions: Thermal cycle application is an effective aging method and air abrasion has different effects on repair bond strength of the restorative materials according to the content of the materials.

Objective : The purpose of this double-blind and split-mouth randomized controlled clinical trial was to evaluate the clinical success of the placement technique (bulk-filling and incremental techniques) of a bulk-fill resin composite in Class II carious lesions. Materials and methods: Two different bulk-fill resin composites, X-tra fil (Voco) and Filtek Bulk Fill (3M ESPE), were used in the bulk-filling and incremental techniques for 20 patients. The study was carried out in 4 groups, with 20 restorations in each group. Restorations were appraised at baseline, 6-month, 2-year, and 4-year recall. World Dental Federation (FDI) and the US Public Health Service (USPHS) criteria were used in the evaluations. The Friedman, Kruskal–Wallis, and Mann–Whitney U tests were used for the statistical analysis. Results: At the end of year 4, there was no loss of restoration in any group. According to the USPHS and FDI criteria, there was a difference in the baseline and 4-year in marginal adaptation and marginal discoloration of the restorations (P < 0.05). When Filtek-Bulk was placed as an incremental technique, there was a minor fracture in four restorations (P > 0.05). In addition, Filtek-Bulk showed a color change according to the results based on both the USPHS and FDI criteria (P < 0.05). The difference between the two placement techniques of each resin composite was not significant at the year 4 recall when all criteria were evaluated (P ˃ 0.05). Conclusions: The 4-year clinical success of the evaluated bulk-fill composites is not dependent on the placement technique used. Clinical relevance: This study can help clinicians choose which technique (bulk fill and incremental techniques) bulk-fill composites can be used. Trial registration: US National Library of Medicine, www.clinicaltrials.gov, ID: NCT04565860 Registered on 10/09/2020. Clinical Evaluation of Bulk-fill resin Composites in Class II Restorations. [ABSTRACT FROM AUTHOR]

Abstract Objective To investigate experimental eggshell powder (ESP) solution application effect on shear bond strength (SBS) test timing of bulk-fill resin composite to bleached enamel. Methods Eighty bovine-extracted anterior teeth were alienated to eight groups (n = 10), representing shear bond strength test timing periods (immediate or delayed) and the remineralizing agents investigated (MI paste Plus and ESP solution). Enamel surfaces were bleached using in-office chemical bleaching agent and the two remineralizing agents were applied then self-etch adhesive and bulk-fill resin composite were performed at 24 h and 14 d before SBS test was done. One-way ANOVA followed by Tukey post hoc test was performed for statistical analysis. Results The control groups showed the highest mean values, while the bleached enamel groups recorded the least mean values. ESP bleached enamel group recorded a significantly higher mean SBS values than MI paste Plus bleached group. Delayed SBS groups showed higher mean values than immediate SBS groups except for control group. Conclusions ESP had a positive and significant effect on SBS of bulk-fill resin composite to bleached enamel surface. Delaying the bonding procedure and restoration of the bleached teeth using resin composite restorations results in a better bond durability.

Objectives: To analyze and compare, in vitro, the microhardness, sorption, solubility, color stability, and cytotoxicity of three types of resin composites: self-adhesive (SARC) (Dyad Flow (DF)/Kerr), bulk-fill (Filtek Bulk Fill Flow (FBF)/3 M ESPE), and conventional (Filtek Z350XT Flow (Z350)/3 M ESPE). Materials and methods: Thirty cylindrical specimens were prepared using a split metal mold (15 mm × 1 mm), divided into 3 groups (n = 10) according to the material used. Vickers hardness (VH) was calculated from three indentations (300gf/15 s) per specimen. The sorption and solubility were measured according to the ISO 4049:2009 specification after storing in distilled water for 7 days. The color of each resin composite was measured using a portable digital spectrophotometer according to the CIELAB system. After a 7-day immersion in coffee, the color variation (∆E) was calculated. Following the ISO 10993:2012, the cytotoxicity in Vero cells was evaluated through the MTT assay. The results were analyzed using the Kruskal–Wallis test to compare the studied groups. The Wilcoxon test was used to compare the assessments in each studied group. For cytotoxicity analysis, the data were compared by the ANOVA test (α = 0.05). Results: DF showed the lowest VH (28.67), highest sorption (0.543 µg/mm3) and solubility (1.700 µg/mm3), and higher ∆E after 7 days of coffee immersion (p = 0.008). The resin composites studied were considered non-cytotoxic. Conclusions: The SARC presented inferior mechanical and physical–chemical properties than bulk-fill and conventional resin composites, with comparable cytotoxicity against Vero cells. Clinical relevance: The simplification of the clinical protocol of SARC can minimize the number of possible failures during the restorative technique. However, considering their inferior physical and mechanical properties, their coverage with materials of higher mechanical properties and physical–chemical stability should be considered. [ABSTRACT FROM AUTHOR]

Background: Proper isolation and restoration of class V subgingival cavities are technique sensitive, thus the resin composite restoration is liable to contamination. This in vitro study was conducted to evaluate the surface microhardness and compressive strength of bulk-fill flowable resin composite after being contaminated during its packing. Methods: Resin composite discs were prepared using split mold. The contaminated specimens were allocated into four groups (n = 20) according to the contaminant used: hemostatic agent (Group 1), alcohol (Group 2), artificial saliva (Group 3) and powdered gloves (Group 4). The non-contaminated specimens (n = 20) were used as control group. The surface microhardness and compressive strength of each group were tested 1-day post-photocuring (n = 5) and 1 month post-photocuring (n = 5). Values were presented as mean, standard deviation values and confidence intervals. Results: The surface microhardness of all groups didn't show a significant difference for different tested groups except for alcohol which showed a significant reduction on surface microhardness compared to control at 1 day post-photocuring (p = 0.001). The highest compressive strength mean values at 1 day and 1 month post-photocuring were recorded in control groups (110.42 MPa and 172.87 MPa respectively), followed by alcohol groups, then hemostatic agent groups, followed by artificial saliva with the least value recorded in powdered gloves groups (56.71 MPa and 49.5 MPa respectively). Conclusions: Contamination of bulk-fill flowable resin composite with hemostatic agent, alcohol, artificial saliva, or powdered gloves during its packing decreased its compressive strength after 1 month post-photocuring rather than affecting its surface microhardness. [ABSTRACT FROM AUTHOR]

This study investigates how the cavity depth of restorations influences the color adjustment potential of universal shade bulk-fill resin composites. Standard cavities, with diameters of 4 mm and depths of either 2 or 4 mm, were created at the center of artificial teeth occlusal surfaces. A structural-colored bulk-fill resin composite and two pigment-incorporated universal shade bulk-fill resin composites were used. Each resin composite was placed into the cavity to assess its color adjustment potential in relation to the artificial tooth color. Following application, the resin composites' surfaces were polished using diamond-impregnated silicone polishers. Color difference analysis revealed ΔE*ab values of 3.3-4.6 and 2.2-9.6 for structural-colored resin composites and pigment-incorporated universal shade resin composites, respectively, as well as ΔE 00 values of 2.7-3.4 and 1.7-5.8 for these resin composites, respectively. These findings suggest that the tested bulk-fill resin composites' color adjustment potential was influenced by restoration depth.

Objectives: This study aims to compare the performance of a bulk-fill and a nanofill resin composite in class II restorations after 6 years. Materials and methods: Fifty patients having at least two class II carious lesions were recruited for the study. One lesion in each patient was randomly assigned to be restored using either the Tetric EvoCeram Bulk Fill (TB) or Filtek Ultimate (FU) resin composites with their respective adhesives. One hundred four restorations were placed by two calibrated operators. Restorations were evaluated at baseline and annually over the course of 6 years by two examiners using modified USPHS criteria. Data were statistically analyzed using the Chi-square and Cochran Q tests (p < 0.05). Results: Sixty-six restorations in 33 patients were evaluated after 6 years. Only one restoration was lost from FU group at 5 years. At the end of 6 years, marginal discoloration was observed in three (9.1%) TB and eight (36.4%) FU restorations creating a significant difference between the groups (p < 0.05). The FU group showed a significant increase in marginal discoloration at 6 years from the baseline (p < 0.05). Marginal adaptation was rated as Bravo for 9.1% and 24.2% of TB and FU restorations, respectively (p > 0.05). Significant degradation was observed within each group in terms of marginal adaptation (p < 0.05). There were no statistically significant differences between the groups for the other criteria tested (p > 0.05). Conclusions: Bulk-fill restorations performed better for marginal discoloration. The remaining clinical performance criteria of bulk-fill and nanofill resin composite restorations were similar after 6 years. Clinical relevance: Bulk-fill resin might be a better alternative to incrementally placed restorative in terms of marginal discoloration under clinical conditions. [ABSTRACT FROM AUTHOR]

Objective: To investigate experimental eggshell powder (ESP) solution application effect on shear bond strength (SBS) test timing of bulk-fill resin composite to bleached enamel. Methods: Eighty bovine-extracted anterior teeth were alienated to eight groups (n = 10), representing shear bond strength test timing periods (immediate or delayed) and the remineralizing agents investigated (MI paste Plus and ESP solution). Enamel surfaces were bleached using in-office chemical bleaching agent and the two remineralizing agents were applied then self-etch adhesive and bulk-fill resin composite were performed at 24 h and 14 d before SBS test was done. One-way ANOVA followed by Tukey post hoc test was performed for statistical analysis. Results: The control groups showed the highest mean values, while the bleached enamel groups recorded the least mean values. ESP bleached enamel group recorded a significantly higher mean SBS values than MI paste Plus bleached group. Delayed SBS groups showed higher mean values than immediate SBS groups except for control group. Conclusions: ESP had a positive and significant effect on SBS of bulk-fill resin composite to bleached enamel surface. Delaying the bonding procedure and restoration of the bleached teeth using resin composite restorations results in a better bond durability. [ABSTRACT FROM AUTHOR]

Bulk-fill resin composites represent an excellent alternative to the conventional incremental layering technique for the reduction of polymerization stress on the adhesive interface. Marginal seal can be further improved by the incorporation of bioactive fillers, such as those encountered in Giomers. However, the high translucency required for the adequate polymerization of bulk-fill materials can seriously jeopardize the final aesthetic outcome of the restorations, especially in the presence of inhomogeneous or stained dentin substrates. The aim of this case report was to present the combined use of two bulk-fill Giomer materials (Beautifil Bulk Flowable and Beautifil II LS, Shofu) for the restoration of three posterior maxillary teeth displaying a black stained dentin substrate due to amalgam corrosion products. This technique allowed completion of the restorations with a satisfactory aesthetic and biomimetic outcome. The adequate preservation of the anatomy and function of the three restorations after 24-months follow-up, provides evidence of the enhanced marginal sealing capacity of these bioactive materials and the success of bulk-fill techniques over time.

Introduction: The aim of this study was to evaluate the effect of photo-activation methods on the shrinkage behavior of bulk-fill resin composites. Materials and Methods: Three bulk-fill resin composites (Tetric N-Ceram bulk-fill, Xtra fill, and Filtek flowable) were compared in terms of polymerization shrinkage, shrinkage stress, and degree of conversion (DC). Two curing methods were used: 1) conventional and 2) soft-start curing. Five disk-shaped specimens of each bulk-fill composite were fabricated. The deflection disk method and custom-made linear variable differential transformer (LVDT) device evaluated the dimensional changes during polymerization. Universal testing machine was used to measure shrinkage stress. To evaluate DC, the absorbance peaks were obtained using Fourier Transformation Infrared Spectroscopy (FTIR). Data were analyzed by one-way ANOVA and Tukey test. Results: Tetric N-Ceram bulk-fill (conventional mode) showed the highest polymerization shrinkage rate. Filtek flowable resin composite showed least amount of shrinkage stress and highest DC, while Xtra fill (with conventional curing) showed the highest shrinkage stress. Conclusion: Photo-activation method had no effect on decreasing the polymerization shrinkage except for Tetric N-Ceram; also, polymerization shrinkage stress in Filtek flowable composites with both curing methods was less than other groups. DC was product dependent.

This study evaluated the load-bearing capacity of fiber-reinforced composite (FRC) direct inlay-retained resin-bonded fixed dental prosthesis (RBFDP) made of bulk-fill or conventional hybrid resin – composites after cyclic loading. Sound human teeth (N = 50) were embedded in acrylic until cemento-enamel junction (CEJ) and randomly divided into five experimental groups to receive RBFDPs: (a) Sonic Fill (SF-KaVo and Kerr Dental), (b) Venus Bulk Fill (VB-Kulzer), (c) Quixfill (QF-Dentsply DeTrey), (d) Tetric EvoCeram Bulk Fill (TE-Ivoclar Vivadent), and (e) Clearfil Photo Posterior (CP-Kuraray). All RBFDPs were reinforced with E-glass fiber (everStick). While premolar pontics were build up incrementally in group CP, in other groups resin composites were applied bulk. RBFDPs were subjected to cyclic loading for 1.2 × 106 cycles in the water at intervals of 60 s between 5 °C and 55 °C. Initial (Finitial) and maximal (Fmax) load-bearing capacity (Newton) of the RBFDPs were measured in the Universal Testing Machine (1 mm/min). Data were analyzed using two-way ANOVA and Tukey's tests (α = 0.05). Significant difference was found between the groups for Finitial (142 ± 84 to 284 ± 198) and Fmax (408 ± 65 to 688 ± 306) (p<.05). All bulk-fill resins (SF, VB, QF, and TE) did not show significant difference to conventional resin composite (CP) in terms of Finitial and Fmax values (p>.05). Weibull distribution of Finitial values (1.63–2.03) was lower than those of Fmax shape values (2.05–8.39) where TE showed the highest results. CP group showed more repairable failures. Bulk-fill composites could be an alternative to conventional hybrid resin composites in the fabrication of direct FRC RBFDPs. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the influence of the restorative material and matrix system on proximal contact tightness and morphological characteristics of class II restorations in primary molars.Methods: Occluso-mesial cavities in second primary artificial molars were randomly restored using different materials (Filtek Z500 or Filtek Bulk Fill composites or high-viscosity glass ionomer cement Ketac Universal) and different matrix system (Tofflemire, AutoMatrix, matrix band with ring, contoured sectional matrix) (n = 12). Proximal contact tightness was measured using a custom-made device in an Instron 3345, and proximal surface morphology and marginal adaptation were scored after digital scanning. Two-way ANOVA, Tukey and Fischer's exact tests were performed (P < 0.05).Results: Proximal contact tightness values were significantly influenced by the restorative material (P < 0.05), the matrix system (P < 0.001), and their interaction (P < 0.01). Both resin composites showed statistically differences in proximal shape according to the matrix used to restore and exhibited overhanging margins. Ketac Universal restorations showed similar morphology and gaps on the margins regardless of the matrix system.Conclusions: Overall, both composite restorations achieved tighter proximal contact than those restored with the high-viscosity glass ionomer cement. None of the matrix systems tested provided a convex seamless proximal morphology. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of (i) a high-irradiance (3s) light-curing protocol versus (ii) two standard-irradiance (10s) protocols on 2D temperature maps during intra-dental photo-irradiation within a molar cavity restored with either Ultra-Rapid Photo-Polymerized Bulk Fill (URPBF) composites or a pre-heated thermo-viscous bulk-fill composite, compared to a standard bulk-fill resin-based-composite (RBC). The specific objectives included visual assessment of the temperature maps and quantitative assessment of several temperature/time plots at four different locations. A caries-free lower first molar cavity served as a natural tooth mold. Resin composites were placed without intermediary adhesive. Two URPBF composites (PFill; PFlow) and one pre-heated thermo-viscous bulk-fill composite (Viscalor : VC) were compared to a contemporary bulk-fill composite (One Bulk Fill: OBF). Two LED-LCU devices were used: Bluephase PowerCure (PC) and Elipar S10 (S10), with three light-irradiation protocols (PC-3s, PC-10s and S10-10s). 2D temperature maps over the entire coronal area were recorded for 120 s during and after irradiation using a thermal imaging camera. Changes at four different levels were selected from the data sets: (0, 2 and 4 mm from the cavity top and at 1 mm below the dentin cavity floor). The maximum temperature attained (T max), the mean temperature rise (ΔT), the time (s) to reach maximum temperature and the integrated areas (°C s) under the temperature/time (T/t) plots were identified. Data were analysed via three-way ANOVA, One-way ANOVA, independent t-tests and Tukey post-hoc tests (p < 0.05). All RBCs showed qualitatively similar temperature-time profiles. PFlow reached T max in the shortest time. PC-3s (3000 mW/cm2) generated comparable ΔT to S10-10s, except with PFill, where ΔT was greater. Despite the same irradiance (1200 mW/cm2), Elipar S10 led to higher T max and ΔT compared to PC-10s. The highest T max and ΔT were observed at the 2 mm level, and the lowest were at 1 mm depth into the underlying dentin. Coronal 2D temperature maps showed rises largely confined within the bulk-fill RBC materials, with maxima at 2 mm rather than 4 mm depth indicating some extent of thermal insulation for the underlying dentin and pulp. RBCs polymerized via different irradiation protocols showed similar temperature changes. With the PC-3s protocol – also with pre-heated VC – minimal temperature rises at 1 mm within dentin suggest their clinical safety when sufficient remaining dentin thickness is present. [ABSTRACT FROM AUTHOR]

Objectives: To assess the clinical performance of class II restorations performed by repeatedly preheated resin composite "RC" at 68 °C up to ten times., Methods: 105 patients were selected and randomized into three groups, each comprising 35 patients. Each patient was provided with a single class II Bulk-fill resin composite "BF-RC" posterior restoration based on the number of preheating cycles; group I (H0): The BF-RC was packed non-heated, group II (H1): BF-RC preheated once, and group III(H10): BF-RC preheated ten cycles. These restorations were evaluated at 1, 3,6, and 12 months, using the modified United States Public Health Service "USPHS". Statistical analysis was performed using Kruskal-Wallis test, Mann Whitney U test, and Friedmann test, where p = 0.05., Results: All the 105 restorations did not suffer from any clinical situation that recommended replacement regarding retention, fracture, secondary caries, or anatomical form. Although all performed restorations did have Alpha and Bravo scores with good clinical performance, the non-preheated RC restorations"" suffered from relatively inferior clinical performance through the follow-up period regarding marginal adaptation, marginal discoloration, and color matching when compared to preheated groups. One and ten times of preheating conducted better clinical performance., Conclusions: After 12-months follow-up, although no restoration needed replacement or repair in the 3 tested groups, restorations with single and ten times of preheating aided in better clinical performance of RC restorations compared to the non-preheated restorations. Preheating of RC for 10 times could be used safely with good clinical performance of restorations., Clinical Significance: By continually preheating RC syringe up to ten times, the dentist will not only benefit from the enhanced clinical performance and easiness of application but also will use preheated RC syringes without hesitation, relying on the absence of drawbacks related to multiple preheating cycles., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objective: To analyse the bond quality in dentine post-ageing after salivary contamination and decontamination at different stages of dental adhesive application. Materials and methods: A total of 1120 human dentine specimens were randomly allocated to 14 groups for four intervals (n = 20) to be treated with a self-etching (SE) and universal (U) adhesive. The saliva contamination and decontamination were implemented after surface preparation, after primer application (for SE) and after adhesive curing. The decontamination groups were either rinsed and air-dried or rinsed, air-dried and reapplied with adhesive. They were stored (37 °C, distilled water) for four intervals (1 week, 1 month, 3 months and 1 year) and subjected to shear bond strength (SBS) test at a crosshead speed of 0.5 mm/min. Result: One-way ANOVA with Tukey's test (α = 0.05) revealed significant reduction in SBS in all the groups in U adhesive compared with the control group at 1 week (p < 0.0001) and in SE when the contamination took place after primer application. However, decontamination improved the SBS in SE but not in U adhesive. The univariate analysis confirmed significant influences (p < 0.0001) seen by treatment procedure ( η p 2 =0.075), type of adhesive ( η p 2 = 0.328), ageing ( η p 2 = 0.13), experimental groups ( η p 2 = 0.518), and the stage of influence ( η p 2 = 0.60). Conclusion: Saliva contamination is detrimental after primer application in SE but, decontamination regained the SBS and maintained it over time. In U adhesive, SBS deteriorated over time irrespective of the contamination. Clinical relevance: Salivary contamination showed different influences on SBS at various stages of restoration with contemporary dental adhesives. [ABSTRACT FROM AUTHOR]

Objectives: This study evaluated the influence of cavity depth on polymerization shrinkage of bulk-fill resin composites with and without adhesive resin. Materials and methods: Standardized box-shaped cavities (width, 4 mm; length, 5 mm, depth, 2 mm or 4 mm) were made on occlusal surfaces of extracted human third molars (N = 60). The teeth were assigned to 3 groups to receive bulk-fill resin composites (low-viscosity bulk-fill, SDR; high-viscosity bulk-fill; Filtek Bulk-Fill—FB; and TetricEvo Ceram Bulk-Fill—TB) in the prepared cavities with and without adhesive resin (Clearfil S3 Bond). Each specimen (n = 5 per group) was scanned twice using microcomputed tomography (micro-CT): once after application of the resin composite to the cavity prior to polymerisation and once after polymerisation. The shrinkage of volumetric loss (%) was measured using micro-CT. Data were analysed using Kruskal-Wallis and Mann-Whitney U tests (alpha = 0.05). Results: The material type (p < 0.05), application of adhesive resin (p < 0.05) and cavity depth (p < 0.05) significantly affected the shrinkage values. The interaction terms were also significant (p < 0.05). All the bulk-fill resin composites tested showed significantly less shrinkage when applied in cavities with adhesive resin (0.94–2.55) compared with those without (2.01–3.45) (p < 0.05) and presented significantly more shrinkage after polymerisation (p < 0.05). At a 2-mm cavity depth without (2 mm, 2.28; 4 mm, 2.41) and with adhesive (2 mm, 0.94; 4 mm, 1.67), significantly less shrinkage was observed with FB compared with SDR and TB (p < 0.05). At a 4-mm cavity depth without (3.14) and with adhesive (2.55), SDR showed significantly higher shrinkage compared with FB and TB (p < 0.05). Conclusions: The bulk-fill composites tested presented less shrinkage when used in conjunction with adhesive resin application on dentin. Overall, the low-viscosity bulk-fill resin SDR showed more shrinkage compared with high-viscosity resins tested. Clinical relevance: Low- or high-viscosity bulk-fill resin composites should be applied on dentin after application of adhesive resin to decrease shrinkage. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to evaluate the effect of photo-activation methods on the shrinkage behavior of bulk-fill resin composites. Materials and Methods: Three bulk-fill resin composites (Tetric N-Ceram bulk-fill, Xtra fill, and Filtek flowable) were compared in terms of polymerization shrinkage, shrinkage stress, and degree of conversion (DC). Two curing methods were used: 1) conventional and 2) soft-start curing. Five disk-shaped specimens of each bulk-fill composite were fabricated. The deflection disk method and custom-made linear variable differential transformer (LVDT) device evaluated the dimensional changes during polymerization. Universal testing machine was used to measure shrinkage stress. To evaluate DC, the absorbance peaks were obtained using Fourier Transformation Infrared Spectroscopy (FTIR). Data were analyzed by one-way ANOVA and Tukey test. Results: Tetric N-Ceram bulk-fill (conventional mode) showed the highest polymerization shrinkage rate. Filtek flowable resin composite showed least amount of shrinkage stress and highest DC, while Xtra fill (with conventional curing) showed the highest shrinkage stress. Conclusion: Photo-activation method had no effect on decreasing the polymerization shrinkage except for Tetric N-Ceram; also, polymerization shrinkage stress in Filtek flowable composites with both curing methods was less than other groups. DC was product dependent. [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to investigate the degree of C=C double bond conversion of high-viscosity dimethacrylate- or ormocer-based bulk-fill composites as a function of measurement depth. Four bulk-fill composites (Tetric EvoCeram Bulk Fill, x-tra fil, SonicFill, and Bulk Ormocer) and the conventional nanohybrid composite Tetric EvoCeram were applied in standardized Class II cavities (n = 6 per group) and photoactivated for 20 s at 1350 mW/cm2. The degree of conversion of the composites was assessed using Fourier-transform infrared spectroscopy at seven measurement depths (0.15, 1, 2, 3, 4, 5, 6 mm). Data were analyzed using repeated measures ANOVA and one-way ANOVA with Bonferroni post-hoc tests (α = 0.05). The investigated bulk-fill composites showed at least 80% of their maximum degree of conversion (80% DCmax) up to a measuring depth of at least 4 mm. Tetric EvoCeram Bulk Fill and Bulk Ormocer achieved more than 80% DCmax up to a measuring depth of 5 mm, x-tra fil up to 6 mm. The conventional nanohybrid composite Tetric EvoCeram achieved more than 80% DCmax up to 3 mm. In contrast to the conventional composite, the investigated ormocer- and dimethacrylate-based bulk-fill composites can be photo-polymerized in thick layers of up to at least 4 mm with regard to their degree of C=C double bond conversion.

Objective: In the present study, the ability of posterior resin composite to repair aged bulk‐fill resin composite and vice versa were assessed by shear bond strength testing. Materials and Methods: Resin composite substrates were aged and surfaces were abraded with abrasive papers, then bulk‐fill substrates were repaired with posterior resin composite and vice versa using different surface treatments (no surface treatment [control]; etching with 37% phosphoric acid [H3PO4] for 20 seconds; etching with 10% hydrofluoric acid [HF] for 20 seconds; etching with 37% H3PO4 for 20 seconds + adhesive application; etching with 10% HF for 20 seconds + adhesive application; adhesive application only). Shear bond strengths (SBS) were then measured and surface roughness values (Ra) were determined. Cohesive strengths of nonaged resin composites were measured and used as reference groups. Resin composite surfaces after acid etching were evaluated by SEM. Data were analyzed using ANOVA and Fisher's LSD tests (P < .05). Results: ANOVA showed that resin composite repair type did not affect SBS significantly (P = .850), while it showed that surface treatments significantly affected the SBS (P = .000). Only a combination of etching with 10% HF for 20 seconds with resin adhesive application provided similar SBS values with those of the positive control. Conclusions: It was concluded that the aged bulk‐fill resin composite would be effectively repaired with conventional posterior resin composite or vice versa if proper repair protocol was deployed. Clinical Significance: The combination of 10% HF etching and adhesive application would provide efficient repair strength when the aged bulk fill resin composite is repaired with conventional posterior resin composite or vice versa. [ABSTRACT FROM AUTHOR]

Objectives: The study aims analyzing if improved opacity in modern high-viscosity bulk-fill resin composites (BF-RBC) contradicts with the sufficiency of curing and to assess material's tolerance to less ideal curing conditions.Materials and methods: Simulated large cavities (10 × 6) mm were filled in one increment with three BF-RBCs (Filtek One, FO; Tetric Evo Ceram Bulk Fill, TEC-BF; SonicFill2, SF2). One central and two peripheral (4 mm apart from the center) micromechanical property line-profiles (HV, Vickers hardness; YHU, indentation modulus) were measured in 0.2-mm steps at 24 h post-polymerization (n = 6). Depth of cure (DOC) was calculated from the HV variation in depth. A scratch test (DOCscratch test) estimated the tolerance in polymerization when simulating clinically relevant curing conditions (exposure distance up to 7 mm; centered and with a 3-mm offset placement of the LCU). Irradiance and spectral distribution of the used light curing unit (LCU) were assessed at various curing conditions.Results: DOC varied among 3.6 mm (SF2, peripheral) and 5.7 mm (FO, central). The BF-RBC influences DOC stronger (p < 0.001, ηP2 = 0.616) than the width (p < 0.001, ηP2 = 0.398). Significant lower DOC (t test) was measured peripheral compared to center in all materials. YHU was more sensitive to the varied parameters as HV. DOCscratch test varied among 2.4 mm (SF2, 3-mm offset, exposure distance 7 mm) and 3.9 mm (FO, center, 0 mm).Conclusions: Whether opacity competes with DOC is material dependent. BF-RBCs tolerate small variations in LCU's centricity better than variations in exposure distance.Clinical relevance: The upper incremental thickness threshold of 4 or 5 mm was not reached in all BF-RBCs under simulated clinically relevant curing conditions. [ABSTRACT FROM AUTHOR]

The addition of RAFT (reversible addition-fragmentation chain transfer) agents to the matrix formulation of a bulk-fill resin composite can significantly decrease the required curing time down to a minimum of 3 s. Evaluating the long term-stability of this resin composite in relation to varied curing conditions in an in-vitro environment was this study’s goal. Specimens were produced according to either an ISO or one of two clinical curing protocols and underwent a maximum of three successive aging procedures. After each one of the aging procedures, 30 specimens for each curing condition were extracted for a three-point bending test. Fragments were then stereo-microscopically characterized according to their fracture mechanism. Weibull analysis was used to quantify the reliability of each aging and curing combination. Selected fragments (n = 12) underwent further testing via depth-sensing indentation. Mechanical values for either standardized or clinical curing were mostly comparable. However, changes in fracture mechanism and Weibull modulus were observed after each aging procedure. The final procedure exposed significant differences in the mechanical values due to curing conditions. Curing conditions with increased radiant exposure seemingly result in a higher crosslink in the polymer-matrix, thus increasing resistance to aging. Yet, the clinical curing conditions still resulted in acceptable mechanical values, proving the effectiveness of RAFT-polymerization.

This in vitro study examined the margin integrity of sculptable and flowable bulk-fill resin composites in Class II cavities of primary molars. Standardized Class II cavities were prepared in human primary molars and restored with the following resin composite materials after application of a universal adhesive: a sculptable bulk-fill composite (Tetric EvoCeram Bulk Fill (TEC) or Admira Fusion x-tra (AFX)), a flowable bulk-fill composite (Venus Bulk Fill (VBF) or SDR), or a conventional composite (Filtek Supreme XTE (FS)). The bulk-fill materials were applied in 4 mm layers, while the conventional composite was applied in either 2 mm (FS2, positive control) or 4 mm layers (FS4, negative control). The specimens were exposed to thermo-mechanical loading (TML) in a computer-controlled masticator. A quantitative margin analysis was performed both before and after TML using scanning electron microscopy, and the percentage of continuous margins (margin integrity) was statistically analyzed (α = 0.05). All composites showed a significant decline in margin integrity after TML. AFX exhibited the significantly highest margin integrity of all materials after TML (97.5 ± 2.3%), followed by FS2 (79.2 ± 10.8%), TEC (73.0 ± 9.1%), and FS4 (71.3 ± 14.6%). SDR (43.6 ± 22.3%) and VBF (25.0 ± 8.5%) revealed the lowest margin integrity. In conclusion, the tested sculptable bulk-fill materials show similar or better margin integrity in primary molars than the conventional resin composite placed in 2 mm increments.

This study compared two resin composites with similar filler systems and different matrix compositions. The depth of cure (DoC), polymerization shrinkage, and marginal leakage were evaluated. A Filtek Bulk Fill resin composite (FB) and a Filtek Supreme resin composite (FS) were used. For the DoC and polymerization shrinkage, cylindrical specimens with different thicknesses were prepared. The DoC was attributed to the bottom/top ratios of Vickers microhardness numbers. For polymerization shrinkage, each specimen was firstly scanned using micro-computed tomography (µCT) then cured for 20 s, then for 10 s, and then for 10 s, and they were rescanned between each curing time. Data were processed using the Mimics software. For marginal leakage, standardized 5 mm cavities were prepared in 90 molars. After etching and bonding, materials were packed according to groups: FB-bulk, FB-incremental, and FS-incremental, which were cured for 20, 30, and 40 s, respectively. After thermo-cycling, teeth were stored in 1% methylene blue dye for 24 h and then sectioned and observed for dye penetration. The results showed insignificant differences in the shrinkage and leakage between the different packing techniques and curing times of both materials. In conclusion, the introduction of a novel matrix into resin composite composition enabled bulk-filling in one layer up to 5 mm deep while keeping a tolerable polymerization shrinkage.

Objective: To evaluate scientific evidence regarding depth of cure of bulk‐fill resin composites (BFRCs) and related factors. Material and Methods: PubMed/Medline, Embase, Scopus, and ISI Web of Science databases were accessed from October 2016 to May 2017. Investigations published in English language, assessing depth of cure of BFRCs by microhardness test and/or degree of conversion (DC) were included. Studies using exclusively ISO 4049, employing specimens deepness less than 4 mm, as well as those not reporting exposure time and/or irradiance from light curing units (LCUs) were excluded. Results: In total, 742 studies were found from which 33 were included. From 21 studies evaluating BFRCs microhardness, 10 showed acceptable bottom/top ratios (≥0.8) for all tested materials. However, material‐dependent results and non‐satisfactory bottom/top microhardness ratios (<0.8) were reported in 9 and 2 investigations, respectively. From 19 studies that assessed DC, 11 showed acceptable results (≥50%) for all tested BFRCs, while 8 studies reported material‐dependent outcomes. Overall, irradiance from LCUs ranged from 650 to 1330 mW/cm2 and exposure time from 5 to 60 seconds. Favorable depth of cure results were observed with the use of LCUs emitting irradiance ≥1000 mW/cm2 and exposure times ≥20 seconds. Conclusions: High depth of cure rates by BFRCs, depends on some factors as material, irradiance and exposure time. Polywave LCUs were useful but not essential on polymerizing alternative photoinitiator‐containing BFRC. Clinical Significance: LED curing devices (polywave or monowave) displaying an irradiance ≥1000 mW/cm2 and 20 seconds of exposure time are imperative to accomplish successful polymerization of most BFRCs. [ABSTRACT FROM AUTHOR]

Abstract Objectives The purpose of this study was to investigate the simulated cuspal deflection and flexural properties of high viscosity bulk-fill and conventional resin composites. Methods Seven high viscosity bulk-fill resin composites and eight conventional resin composites were used. Aluminum blocks (10 mm x 8 mm x 15 mm) with a mesio-occlusal-distal (MOD) cavity [4 (W) mm x 8 (L) mm x 4 (D) mm] were prepared and randomly divided into groups for different measurement techniques [micrometer vs CSLM] and further subdivided according to type of resin composite (high viscosity bulk-fill vs conventional resin composite). The simulated cuspal deflection resulting from the polymerization of resin composite bonded to a precisely machined MOD cavity within an aluminum block was measured with either a novel highly accurate submicron digimatic micrometer (MDH-25 M, Mitsutoyo, Tokyo, Japan) or a confocal laser scanning microscope (CLSM, VK-9710, Keyence, Tokyo, Japan) cuspal measurement method. In addition, flexural properties of tested resin composites were measured to investigate the relationship between simulated cuspal deflection and flexural properties. Scanning electron microscopy observation of tested resin composites was also conducted. Results The simulated cuspal deflection of high viscosity bulk-fill resin composites was similar to that of conventional resin composites, regardless of measurement method. There were no statistically significant differences (p > 0.05) between the micrometer and CLSM cuspal measurement methods. There were statistically significant differences (p < 0.05) in flexural strength and elastic modulus depending on the material, regardless of the type of resin composite. Pearson correlation analysis did not show any statistically significant (p < 0.05) relationship between flexural properties and cuspal deflection. Conclusions The results of this study indicate that high viscosity bulk-fill resin composites show similar cuspal deflection with bulk-filling techniques, to those shown by conventional resin composites with incremental filling techniques. Simulated cuspal deflection can be measured using either a micrometer or CLSM, but this experiment failed to show any relationship between the flexural properties and simulated cuspal deflection of resin composites. Significance High viscosity bulk-fill resin composites produce the same level of cuspal deflection as a conventional incrementally filled resin composite. [ABSTRACT FROM AUTHOR]

Objective: The aim of this research was to investigate the effect of various mouthwashes for COVID-19 prevention on surface hardness, roughness, and colour changes of bulk-fill and conventional resin composites and determine the pH and titratable acidity of mouthwashes., Methods: Four hundred eighty specimens were fabricated in cylindrical moulds (10 mm in diameter and 2 mm in thickness). Before immersion, baseline data of surface hardness, roughness, and colour values were recorded. Each product of specimens (Filtek Z350XT, Premise, Filtek One Bulk Fill Restorative, SonicFil 2) were divided into 4 groups for 0.2% povidone iodine, 1% hydrogen peroxide, 0.12% chlorhexidine, and deionised water (serving as a control). The specimens were immersed in mouthwashes for 1 minute and then stored in artificial saliva until 24 hours. This process was repeated for 14 days. After immersion, surface hardness, roughness, and colour values of specimens were measured at 7 and 14 days. The data were statistically analysed by 2-way repeated analysis of variance, Tukey honestly significant difference, and t test (P < .05)., Results: After immersion, all mouthwashes caused significantly lower surface hardness and greater roughness and colour values (P < .05) on all resin composites tested., Conclusions: Mouthwashes had an effect on all resin composites evaluated leading to a significant decreased surface hardness and an increased roughness and colour values (P < .05)., Competing Interests: Conflict of interest None disclosed., (Copyright © 2022. Published by Elsevier Inc.)

This in vitro investigation compared the shear bond strength (SBS) of four dentin substitute/replacement materials to caries-affected dentin of primary teeth. Dentin surfaces were randomly divided into four groups of 12 each according to the material used as follows: SDR/Smart Dentin Replacement, Biodentine, Multicore Flow, and Fuji II LC. The SBS was measured and failure modes were determined. There was a statistically significant difference in the mean values of SBS among the four materials (F=741.523, p<0.0001). The mean values of SBS of SDR were statistically significantly higher followed by Multicore Flow compared to the other groups. The mean values of the four materials were significantly different from each other in all combinations of pairs of four materials. The SBS between the four dentin substitute/replacement materials to dentin of primary teeth was significantly different. The highest SBS was for SDR followed by Multicore Flow then Fuji II LC and the lowest was for Biodentine. [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to investigate the degree of C=C double bond conversion of high-viscosity dimethacrylate- or ormocer-based bulk-fill composites as a function of measurement depth. Four bulk-fill composites (Tetric EvoCeram Bulk Fill, x-tra fil, SonicFill, and Bulk Ormocer) and the conventional nanohybrid composite Tetric EvoCeram were applied in standardized Class II cavities ( n = 6 per group) and photoactivated for 20 s at 1350 mW/cm 2 . The degree of conversion of the composites was assessed using Fourier-transform infrared spectroscopy at seven measurement depths (0.15, 1, 2, 3, 4, 5, 6 mm). Data were analyzed using repeated measures ANOVA and one-way ANOVA with Bonferroni post-hoc tests (α = 0.05). The investigated bulk-fill composites showed at least 80% of their maximum degree of conversion (80% DC max ) up to a measuring depth of at least 4 mm. Tetric EvoCeram Bulk Fill and Bulk Ormocer achieved more than 80% DC max up to a measuring depth of 5 mm, x-tra fil up to 6 mm. The conventional nanohybrid composite Tetric EvoCeram achieved more than 80% DC max up to 3 mm. In contrast to the conventional composite, the investigated ormocer- and dimethacrylate-based bulk-fill composites can be photo-polymerized in thick layers of up to at least 4 mm with regard to their degree of C=C double bond conversion.

The addition of RAFT (reversible addition-fragmentation chain transfer) agents to the matrix formulation of a bulk-fill resin composite can significantly decrease the required curing time down to a minimum of 3 s. Evaluating the long term-stability of this resin composite in relation to varied curing conditions in an in-vitro environment was this study's goal. Specimens were produced according to either an ISO or one of two clinical curing protocols and underwent a maximum of three successive aging procedures. After each one of the aging procedures, 30 specimens for each curing condition were extracted for a three-point bending test. Fragments were then stereo-microscopically characterized according to their fracture mechanism. Weibull analysis was used to quantify the reliability of each aging and curing combination. Selected fragments (n = 12) underwent further testing via depth-sensing indentation. Mechanical values for either standardized or clinical curing were mostly comparable. However, changes in fracture mechanism and Weibull modulus were observed after each aging procedure. The final procedure exposed significant differences in the mechanical values due to curing conditions. Curing conditions with increased radiant exposure seemingly result in a higher crosslink in the polymer-matrix, thus increasing resistance to aging. Yet, the clinical curing conditions still resulted in acceptable mechanical values, proving the effectiveness of RAFT-polymerization. [ABSTRACT FROM AUTHOR]

This in vitro study examined the margin integrity of sculptable and flowable bulk-fill resin composites in Class II cavities of primary molars. Standardized Class II cavities were prepared in human primary molars and restored with the following resin composite materials after application of a universal adhesive: a sculptable bulk-fill composite (Tetric EvoCeram Bulk Fill (TEC) or Admira Fusion x-tra (AFX)), a flowable bulk-fill composite (Venus Bulk Fill (VBF) or SDR), or a conventional composite (Filtek Supreme XTE (FS)). The bulk-fill materials were applied in 4 mm layers, while the conventional composite was applied in either 2 mm (FS2, positive control) or 4 mm layers (FS4, negative control). The specimens were exposed to thermo-mechanical loading (TML) in a computer-controlled masticator. A quantitative margin analysis was performed both before and after TML using scanning electron microscopy, and the percentage of continuous margins (margin integrity) was statistically analyzed (α = 0.05). All composites showed a significant decline in margin integrity after TML. AFX exhibited the significantly highest margin integrity of all materials after TML (97.5 ± 2.3%), followed by FS2 (79.2 ± 10.8%), TEC (73.0 ± 9.1%), and FS4 (71.3 ± 14.6%). SDR (43.6 ± 22.3%) and VBF (25.0 ± 8.5%) revealed the lowest margin integrity. In conclusion, the tested sculptable bulk-fill materials show similar or better margin integrity in primary molars than the conventional resin composite placed in 2 mm increments. [ABSTRACT FROM AUTHOR]

This study compared two resin composites with similar filler systems and different matrix compositions. The depth of cure (DoC), polymerization shrinkage, and marginal leakage were evaluated. A Filtek Bulk Fill resin composite (FB) and a Filtek Supreme resin composite (FS) were used. For the DoC and polymerization shrinkage, cylindrical specimens with different thicknesses were prepared. The DoC was attributed to the bottom/top ratios of Vickers microhardness numbers. For polymerization shrinkage, each specimen was firstly scanned using micro-computed tomography (µCT) then cured for 20 s, then for 10 s, and then for 10 s, and they were rescanned between each curing time. Data were processed using the Mimics software. For marginal leakage, standardized 5 mm cavities were prepared in 90 molars. After etching and bonding, materials were packed according to groups: FB-bulk, FB-incremental, and FS-incremental, which were cured for 20, 30, and 40 s, respectively. After thermo-cycling, teeth were stored in 1% methylene blue dye for 24 h and then sectioned and observed for dye penetration. The results showed insignificant differences in the shrinkage and leakage between the different packing techniques and curing times of both materials. In conclusion, the introduction of a novel matrix into resin composite composition enabled bulk-filling in one layer up to 5 mm deep while keeping a tolerable polymerization shrinkage. [ABSTRACT FROM AUTHOR]

Objectives: To describe a method of measuring the molar cusp deformation using micro-computed tomography (micro-CT), the propagation of enamel cracks using transillumination, and the effects of hygroscopic expansion after incremental and bulk-filling resin composite restorations., Methods: Twenty human molars received standardized Class II mesio-occlusal-distal cavity preparations. They were restored with either a bulk-fill resin composite, X-tra fil (XTRA), or a conventional resin composite, Filtek Z100 (Z100). The resin composites were tested for post-gel shrinkage using a strain gauge method. Cusp deformation (CD) was evaluated using the images obtained using a micro-CT protocol and using a strain-gauge method. Enamel cracks were detected using transillumination., Results: The post-gel shrinkage of Z100 was higher than XTRA (P < 0.001). The amount of cusp deformation produced using Z100 was higher compared to XTRA, irrespective of the measurement method used (P < 0.001). The thinner lingual cusp always had a higher CD than the buccal cusp, irrespective of the measurement method (P < 0.001). A positive correlation (r = 0.78) was found between cusp deformation measured by micro-CT or by the strain-gauge method. After hygroscopic expansion of the resin composite, the cusp displacement recovered around 85% (P < 0.001). After restoration, Z100 produced more cracks than XTRA (P = 0.012)., Conclusions: Micro-CT was an effective method for evaluating the cusp deformation. Transillumination was effective for detecting enamel cracks. There were fewer negative effects of polymerization shrinkage in bulk-fill resin restorations using XTRA than for the conventional incremental filling technique using conventional composite resin Z100., Clinical Significance: Shrinkage and cusp deformation are directly related to the formation of enamel cracks. Cusp deformation and crack propagation may increase the risk of tooth fracture., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objective: To investigate the impact of storage up to one year on the micro-mechanical properties of dental bioactive restoratives (R) used for bulk-application and their intermediate layer (IL) to dentin (D)., Methods: One giomer bulk-fill resin composite (RBC) and one glass-ionomer cement (GIC) were applied in 5-mm deep Class I cavities, which were prepared in 50 sound human molars. Specimens were stored in distilled water at 37°C for 24h, one week, one month, three months and one year. The variation in micro-mechanical properties (indentation modulus (YHU) and Vickers hardness (HV)) were determined in 100-μm steps in line-profiles located parallel to the tooth axis, starting 0.1mm from the filling surface, through the IL in between R and D, and ending 300μm in D., Results: HV and YHU were influenced by the material (p<0.001, partial eta-squared [Formula: see text] =0.011 and [Formula: see text] =0.395), immersion duration ( [Formula: see text] =0.081, [Formula: see text] =0.081) and depth ( [Formula: see text] =0.050, [Formula: see text] =0.091). The micro-mechanical properties progressively increased with immersion time in both restoratives, with a comparable time-dependency pattern, but to a different extent. IL showed weaker mechanical properties compared to more superficial cavity areas, which were maintained in RBC and even enhanced in GIC during storage. After one year of storage HV ranked in the following sequence: GIC: D: 61.4±7.25-N/mm(2), IL: 86.0±23.63-N/mm(2), R: 112.3±30.36-N/mm(2) and RBC: D: 67.2±11.55-N/mm(2), IL: 76.7±18.88-N/mm(2), R: 94.1±12.28-N/mm(2)., Conclusion: No degradation with aging was identified in the giomer restorative. The gradual ascending transition in micro-mechanical properties from D through R identified in both restoratives might have a positive effect on the bond quality., Clinical Significance: Giomers represent a new category of restoratives with promising clinical behavior and good mechanical stability up to one year of aging under simulated clinical conditions., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objectives: This study evaluated the effects of the resin thickness on the microhardness and optical properties of bulk-fill resin composites., Methods: Four bulk-fill (Venus Bulk Fill, Heraeus Kulzer; SDR, Dentsply Caulk; Tetric N-Ceram Bulk Fill, Ivoclar vivadent; SonicFill, Kerr) and two regular resin composites (Charisma flow, Heraeus Kulzer; Tetric N-Ceram, Ivoclar vivadent) were used. Sixty acrylic cylindrical molds were prepared for each thickness (2, 3 and 4 mm). The molds were divided into six groups for resin composites. The microhardness was measured on the top and bottom surfaces, and the colors were measured using Commission Internationale d'Eclairage (CIE) L (*) a (*) b (*) system. Color differences according to the thickness and translucency parameters and the correlations between the microhardness and translucency parameter were analyzed. The microhardness and color differences were analyzed by ANOVA and Scheffe's post hoc test, and a student t-test, respectively. The level of significance was set to α = 0.05., Results: The microhardness decreased with increasing resin thickness. The bulk-fill resin composites showed a bottom/top hardness ratio of almost 80% or more in 4 mm thick specimens. The highest translucency parameter was observed in Venus Bulk Fill. All resin composites used in this study except for Venus Bulk Fill showed linear correlations between the microhardness and translucency parameter according to the thickness., Conclusions: Within the limitations of this study, the bulk-fill resin composites used in this study can be placed and cured properly in the 4 mm bulk.