Strontium-substituted bioglass-based composite for restoring root surface defects.

Objective: to compare the shear bond strength of resin composite using universal adhesive system containing MDP and resin modified glass ionomer cement to cementum and compare the results with those of cervical dentin. Materials and methods: A total of 12 lower premolars were used in this study, they were sectioned just above the cemento-enamel junction, the roots were then sectioned into two halves and divided into two main groups according to the tooth substrate in which group 1) Cervical dentin and group 2) Cementum. They were further subdivided into two subgroups according to the material used where n= 6 subgroup 1) Resin composite (Brilliant Ever-Glow) using universal adhesive (One coat 7 universal), subgroup 2) Resin modified glass ionomer (Fuji II LC). Shear bond strength was then evaluated for all specimens and statistically analyzed. Results: There was statistically significant difference between resin composite using universal adhesive system and resin modified glass ionomer when applied on cementum. While on comparing the resin composite using universal adhesive system and resin modified glass ionomer on cervical dentin it showed no statistically significant difference. Meanwhile no statistically significant difference was found between cervical dentin and cementum when using resin composite with universal adhesive system. Comparing resin modified glass ionomer on dentin and cementum there was also no statistical difference. Conclusion: using universal adhesive containing MDP with resin composite it showed the same bond strength to cervical dentin and cementum. While the resin modified glass ionomer showed higher bond strength to cementum than that of the universal adhesive system.

Objective:The aim of this study was to comparatively investigate the neutralizing effect of antioxidant treatment and delayed bonding after bleaching with hydrogen peroxide on the shear bond strength of a composite resin (CR) and resin-modified glass ionomer (RmGI) to enamel.Materials and Methods:Ninety-six freshly extracted human 3rd molars with flat enamel surfaces were divided into six experimental groups (n=12/group) and two control groups (n=12/group). After initial preparation, specimens in Groups 1 and 5 (control groups) were not bleached and the buccal enamel surface of specimens were bonded immediately with CR and RmGI. The samples of the remaining groups were all bleached six hours a day for seven days consecutively. Immediately after bleaching, groups two and six specimens were bonded with CR and RmGI. Groups 3 and 7 specimens were immersed in distilled water at 37°C for 7 days and the specimens in Groups 4 and 8 were treated with 10% sodium ascorbate as an antioxidant agent after bleaching. Specimens in Groups 3 and 4 were bonded with CR and Groups 7 and 8 specimens were bonded with RmGI immediately. After specimens were bonded, the shear bond strength (SBS) was measured. The SBS data analyses were subjected to one-way analysis of variance (ANOVA) followed by Tukey test for comparison of specific mean values.Results:The mean SBS value in Group 2 (immediately bonded with CR after bleaching) was significantly lower than other CR groups (P=0.045). RmGI did not bond to buccal enamel surface of specimens in group 6. There was no significant difference between other groups bonded with RmGI (P>0.05).Conclusions:Applying 10% sodium ascorbate hydrogel and one week delay before bonding resulted in reversal of reduced bond strength of CR and RmGI to bleached enamel.

Introduction: Internal bleaching is a treatment option for wightening endodontically treated discolored teeth. Cervical resorption is one of the side effects of this method. The aim of this study was to compare the sealing ability of resin composite and light-cured resin modified glass ionomer (RMGI) as intra-orifice barriers in internal bleaching. Materials &Methods: In this study, 34 single-canal anterior teeth were used. All samples were endodontically prepared and divided into two experimental groups (n=12) and two control groups (n=5). In the experimental groups, Gutta-percha was removed up to 3 mm below the cemento enamel junction (CEJ). RMGI and composite resin was placed over gutta-percha in the experimental groups up to the level of CEJ. After 24-hours incubation period, the bleaching agent (a mixture of sodium perborate and 30% hydrogen peroxide) was placed in the access cavities. The gnehcaelg agents were replaced every 3 days over 9 days. Then, the access cavity was filled with 2% methylene blue for 48 hours. All samples were longitudinally sectioned and the dye penetration range was evaluated using stereomicroscope. Data was statistically analyzed by using T-student test and variance analysis. Results: The microleakage in RMGI group was 0.945mm and in composite resin group was 0.641mm. Statistically, no significant difference was observed in microleakage between the experimental groups (p=0.121). Conclusion: Both materials can be applied as the intra-orifice barriers for internal bleaching.

Aim Several new bioactive compounds were recently introduced to the market with favorable ion release, tooth remineralization, and alkalizing potential. This study sought to compare the phosphate ion release and alkalizing potential of three bioactive materials in comparison with composite resin. Methods Thirty-six discs (2 × 6 mm) were fabricated from Fuji II LC resin modified glass ionomer (RMGI), Activa BioActive, Cention N, and Z250 composite in plastic molds. The specimens were stored in distilled water for 24 and 48 h and 6 months. Half of the specimens were used to assess the phosphate ion release while the other half were used to assess the alkalizing potential 1 h after pH drop from 6.8 to 4. Phosphate ion release was quantified by a spectrophotometer while the pH value was measured by a pH meter. Data were analyzed using two-way ANOVA, one-way ANOVA, and Tukey's HSD test (for pairwise comparisons) at 0.05 level of significance. Results At 24 h, the maximum phosphate ion release in distilled water occurred in the Fuji II LC group followed by Cention N, Activa BioActive, and Z250. At 6 months, Cention N followed by Activa BioActive showed higher phosphate ion release than Fuji II LC and Z250. No significant difference was noted between Activa BioActive and Cention N at any time point. All materials, except for Z250, increased the pH of the environment. Fuji II LC had maximum alkalizing effect at all time points followed by Cention N and Activa BioActive. Conclusion Use of bioactive compounds is a promising method to ensure phosphate ion release, and can have a positive effect on tooth remineralization over time. Also, bioactive compounds can alkalize an acidic environment.

Aim: To compare the microleakage of Cention N, a subgroup of composite resins with a resin-modified glass ionomer (RMGI) and a composite resin. Methods: Class V cavities were prepared on the buccal and lingual surfaces of 46 extracted human molars. The teeth were randomly assigned to four groups. Group A: Tetric N-Bond etch-and-rinse adhesive and Tetric N-Ceram nanohybrid composite resin, group B: Cention N without adhesive, group C: Cention N with adhesive, and group D: Fuji II LC RMGI. The teeth were thermocycled between 5°-55°C (×10,000). The teeth were coated with two layers of nail vanish except for 1 mm around the restoration margins, and immersed in 2% methylene blue (37°C, 24 h) before buccolingual sectioning to evaluate dye penetration under a stereomicroscope (×20). The data were analyzed by the Kruskal-Wallis and Wilcoxon tests (α=0.05). Results: Type of material and restoration margin had significant effects on the microleakage (p<0.05). Dentin margins showed a higher leakage score in all groups. Cention N and RMGI groups showed significant differences at the enamel margin (p=0.025, p=0.011), and for the latter group the scores were higher. No significant difference was found at the dentin margins between the materials except between Cention N with adhesive and RMGI (p=0.031). Conclusion: Microleakage was evident in all three restorative materials. Cention N groups showed similar microleakage scores to the composite resin and displayed lower microleakage scores compared with RMGI.

This study investigated the release and recharge of fluoride by restorative materials. Resin-modified glass ionomers (RGIs), polyacid-modified composite resins (PMCRs) and resin composite containing fluoride were used for comparison of fluoride release. Non-fluoride-releasing resin composite was used as a control. The amounts of fluoride release from RGIs and PMCRs remarkably increased in the citrate-phosphate acid buffer compared with distilled water. The amounts of fluoride recharged in RGIs increased with the concentration of NaF solution, but those of PMCRs exposed to all concentrations of NaF solutions were less than 1.5 ppm. Neither resin composite containing fluoride and non-fluoride-releasing resin composite gave any evidence of recharge. RGIs and PMCRs affected by acid buffer solution could not recharge much fluoride even if they were immersed in the 1000 ppmF NaF solution. The results suggested that the matrix of RGIs and PMCRs functioned as a reservoir of fluoride, but the functions were lost by acid attack.

Objectives: The aesthetic longevity of resin-based restoration materials is a critical factor in dental practice, as color stability directly influences patient satisfaction and the overall success of restorative procedures. This study investigates the impact of different light-curing modes on the color stability of various resin-based materials commonly used in dental restorations. Materials and Methods: A total of five resin composites were selected for this analysis, each subjected to three distinct light-curing modes: standard, high-intensity, and pulse curing. Color measurements were taken using a spectrophotometer before curing and after a simulated aging process that included exposure to staining agents and thermal cycling. The color changes were quantified using the CIEDE2000 color difference formula, which provides a more perceptually relevant assessment of color differences. Results: Results indicated that the curing mode significantly influenced the color stability of the resin composites. High-intensity curing demonstrated superior color retention compared to standard and pulse modes, particularly in materials with higher pigment concentrations. However, some composites exhibited a tendency to darken over time, regardless of the curing method employed. Conclusion: This study underscores the importance of selecting appropriate light-curing techniques to enhance the aesthetic performance of resin-based restorations. The choice of light-curing mode plays a pivotal role in the color stability of resin-based materials, which is essential for maintaining the aesthetic integrity of dental restorations over time. Further research is warranted to explore the underlying mechanisms affecting color stability and to optimize curing protocols for improved clinical outcomes.

Objectives: The aim of the study was to assess the influence of cervical margin relocation (CMR) with two different materials (flowable resin composite and light cure resin modified glass ionomer) on marginal integrity of resin nano ceramic composite restoration after thermo mechanical loading (TML). Materials and Method: A total number of (24) standardized MOD cavities with one proximal box (mesial) with cervical margin located one mm beneath the cement- enamel junction (CEJ) were prepared while keeping the distal box supragingival. The division of teeth into two equal main groups (n=12) based on the kind of restorative materials used for (CMR); group (A):- nanohybrid flowable resin composite (Dyract flow) and group (B):- resin modified glass ionomer (Riva). Both groups were restored with direct nanoceramic resin composite (Zenit). After that, each group was split into two equal subgroups (n=6) based on (TML) was done or not. Result: No statistically significant difference in marginal integrity before and after the (TML) regardless of (CMR) was recorded and the flowable resin group showed higher marginal leakage than the mesial resin modified glass ionomer group after the (TML). Conclusions: (CMR) technique seems to promising acceptable technique without compensatory the marginal integrity, marginal integrity in (CMR) was a material-dependent and the (TML) had no significant effect on marginal integrity regardless of (CMR). Keywords: Cervical margin relocation. Marginal integrity. Thermo mechanical loading

Four light-cured calcium hydroxide and three chemically cured resin-based lining materials were compared for hydoxil ion (OH-) release. Results indicated that the chemically cured calcium hydroxide cements were capable of OH- release for a longer period than the light-cured resin bases. Alkaliner (a chemically cured liner) produced and maintained the highest alkaline environment in the long-term, whereas calcium fluoride liner and Basic-L (both resin-based) showed the lowest values of OH- ion release.

Fluoride release and uptake by aged resin- modified glass ionomers and a polyacid-modified resin composite

The aim of the present study was to evaluate the effect of four different sandwich techniques on gingival microleakage of Class II direct composite resin restorations. Fifty sound human premolars were selected and randomly divided into five groups (n=10). Class II box only cavities were prepared in one of the proximal surfaces of each tooth with a gingival margin located approximately 0.5 mm below the cemento-enamel junction. Group A (control) was restored incrementally with composite resin (Tetric Ceram). Groups B, C, D, and E were restored with the sandwich technique using a compomer (Compoglass F), flowable composite resin (Tetric Flow), self-cure composite resin (Degufill SC), or resin modified glass ionomer (Fuji II LC), respectively. After thermal-load cycling, the specimens were immersed in 0.5% basic fuschin for 24 hours. Dye penetration (10(-1) mm) was detected using a sectioning technique. Data were analyzed with repeated measurements and Duncan test at α=0.05. The least amount of microleakage was detected in the incremental group (1.28 ± 0.98). The sandwich technique using resin modified glass ionomer (7.99 ± 9.57) or compomer (4.36 ± 1.78) resulted in significantly more leakage than did the sandwich technique using flowable (1.50 ± 1.97) or self-cure composite (2.26 ± 1.52). According to the results of this study, none of the four sandwich technique composite resin restorations used in this study could reduce gingival microleakage to a greater degree than the incremental technique.

Objective. Anion powder is a kind of cyclic silicate mineral with antibacterial effect. A new type of composite resin containing anion powder was prepared by adding aion powder into the composite resin. Methods. By using mechanical mixing dispersion and ultrasonic dispersion, silane coupling agent was added, and the anion powder was evenly dispersed in Durafill (DF) composite resin at the proportions of 0, 1%, 2%, 4%, respectively. EDS was used to detect the relative content of anion powder in composite resin, and scanning electron microscope (SEM) was used to observe the dispersion uniformity of anion powder. The friction coefficient (COF) of composite resin containing anion powder was measured by UMT-2MT friction and wear tests. The influence of different proportion of anion powder added to the composite resin on its mechanical properties. The next step is to test the antimicrobial property of the composite resin containing anion powder, in order to find the best proportion of anion powder added to the resin. Results Mechanical agitation dispersion and ultrasonic dispersion were applied, silane coupling agent was added, and anion powder of different proportions was successfully mixed into the composite resin. EDS results showed that anion powder was successfully added into the composite resin, and the surface particles were uniformly dispersed by SEM. The friction and wear experiments showed that the addition of anion powder would change the mechanical properties of the composite resin, and the friction coefficient of the composite resin was higher than that of the control group, and the friction coefficient of the composite resin increased with the increase of anion powder content.

The purpose of this study is was to compare the color stability of alkasite and other restorative materials commonly used in the field of pediatric dentistry and to study a color change in response to various beverages. Test specimens of glass ionomer, resin modified glass ionomer, alkasite restorative material, and composite resin were prepared, and the color stability was measured after thermocycling. Each specimen was also subdivided into 5 groups and submerged in PBS, coffee, green tea, coke, and orange juice to analyze the color change from the original CIE <i>L*a*b*</i> values after 7, 14, 21, and 28 days. Composite resin showed the best color stability after thermocycling, followed by alkasite restorative material, glass ionomer, and resin modified glass ionomer. Submerging in various beverages for 7 days resulted in color change in all test specimens, with alkasite restorative material showing less color change than glass ionomer but greater change than composite resin. Alkasite restorative material showed the greatest color change in coffee, followed by green tea and orange juice, but almost no change in coke and PBS even after 28 days of submersion.

This in vitro study aimed to evaluate the effect of simulated gastric fluid (SGF) and an alginate-based antacid on the surface roughness and color stability of two additively manufactured (AM) and one subtractively manufactured (SM) resin-based restorative materials. A total of 168 disc-shaped specimens (10 × 2 mm) were fabricated from two AM resin composites (Bego VarseoSmile TriniQ [AM-VS] and Saremco Crowntec [AM-C]) and one SM nano-ceramic hybrid (Voco Grandio blocs [SM-V]). Specimens were distributed into seven subgroups (n = 8) based on immersion media: distilled water (control); SGF mixed with artificial saliva (AS) at ratios of 1:1, 1:3, and 1:5; and the same mixtures with 10% alginate-based antacid (Gaviscon®). All solutions were refreshed daily and maintained at 37 °C with gentle agitation for 48 h. Surface roughness (Ra) was measured with a contact profilometer, and color stability (ΔE₀₀) was assessed with a spectrophotometer. Data were analyzed using mixed-model ANOVA and post hoc tests (α = 0.05). Immersion in SGF + AS increased ΔE₀₀ and Ra values in all materials compared with distilled water (p<.001). The highest color change was observed in AM-C at SGF + AS (1:5) (1.87 ± 0.30), whereas SM-V showed the lowest ΔE₀₀ values (1.55 ± 0.04). Surface roughness increased under acidic conditions, with AM-C exhibiting the highest Ra values (1.30 ± 0.02 μm). The alginate-based antacid significantly reduced Ra values for all materials and reduced ΔE₀₀ values in AM-C (1:3 and 1:5) and AM-VS (1:5) (p<.05), with selected antacid-containing subgroups showing values approaching those of the control. Simulated gastric fluid compromised the surface integrity and color stability of CAD/CAM resin-based restorative materials, with material-dependent differences. The addition of an alginate-based antacid mitigated these effects under selected experimental conditions, suggesting a potential protective role against acid-induced degradation.

Bacterial microleakage and pulp inflammation associated with various restorative materials