Compressive strength and fluoride release profile of a glass ionomer cement reinforced with silver-hydroxyapatite-silica hybrid nanoparticles: An in vitro study.

OBJECTIVES: This study aimed to prepare a glass ionomer (GI) cement reinforced with silver-hydroxyapatite-silica (Ag/HA/Si) hybrid nanoparticles and assess its compressive strength and fluoride release profile. MATERIAL AND METHODS: In this in vitro, experimental study, 60 cylindrical specimens were fabricated with 4mm diameter and 6mm height in 6 groups (n=10) using BracePaste composite, GC Fuji II LC pure RMGI, and RMGI reinforced with 0.1wt%, 0.5wt%, 1wt%, and 2wt% Ag/HA/Si hybrid nanoparticles. The specimens were subjected to compressive force in a universal testing machine to measure their compressive strength (MPa). To assess their fluoride release profile, discs with 3mm diameter and 2mm thickness were fabricated from Fuji II LC pure resin-modified glass ionomer (RMGI), and RMGI with 0.1wt%, 0.5wt%, 1wt%, and 2wt% hybrid nanoparticles, and the concentration of released fluoride was measured by a digital ion-selective electrode. Data were analysed by ANOVA and Scheffe test (alpha=0.05). RESULTS: The compressive strength was 114.14MPa for BracePaste composite, and 97.14, 97.84, 100.65, 109.5, and 89.33MPa for GI groups with 0%, 0.1%, 0.5%, 1% and 2% hybrid nanoparticles, respectively, with no significant difference among them (P=0.665). Addition of 1% (0.21±0.07µg/mL, P=0.029) and 2% (0.45±0.22µg/mL, P=0.000) hybrid nanoparticles to RMGI significantly increased the amount of released fluoride, compared with the control group (0.09±0.03µg/mL). CONCLUSIONS: Addition of Ag/HA/Si hybrid nanoparticles to RMGI in the tested concentrations had no significant effect on its compressive strength but addition of 1wt% and 2wt% concentrations of Ag/HA/Si hybrid nanoparticles increased its fluoride release potential.

Novel microbial synthesis of titania nanoparticles using probiotic Bacillus coagulans and its role in enhancing the microhardness of glass ionomer restorative materials.

Dental caries is a commonly occurring non-communicable disease throughout the world that might compromise the quality of any individual's life. Glass ionomer cements (GIC) are the most acceptable restorative materials due to their ease of manipulation, minimal tooth loss and least invasive strategy; however, they lack mechanical stability that has become a point of concern. Nanoparticles (NPs) are an outstanding option for modifying and enhancing the properties of dental materials. The focus of this study was to prepare novel, biocompatible titania dioxide (TiO2) NPs as a dental-restorative material using an efficient probiotic Bacillus coagulans. The prepared NPs were incorporated into glass ionomer restorative material at varying concentrations and investigated for cell viability percentage, microhardness and surface morphology. Results indicated that pure 100% anatase phase TiO2 NPs with particle size of 21.84 nm arranged in smooth, spherical agglomerates and clusters forms. These NPs depicted cell viability > 90%, thus confirming their non-cytotoxic behavior. GIC restorative materials reinforced by 5% titania (TiO2) NPs demonstrated the highest microhardness in comparison to the control group and other experimental groups of the study. Surface morphology analysis revealed a reduction in cracks in this novel dental-restorative material supporting its compatible biological nature with better hardness strength and negligible crack propagation. Overall, these results indicated that TiO2 NPs produced using a biological approach could be easily used as restorative materials in dental applications.

Minimal intervention dentistry: What is its clinical application and effectiveness in different continents? - A scoping review.

The aim of minimal intervention dentistry (MID) is to maximize the preservation of dental tissues through the use of modern and effective techniques and procedures. The central objective of MID is to increase the functional life of dental elements and, consequently, the quality of life of the population. The present study aimed to analyze and map the diffusion and clinical application of MID in different continents around the world. To perform this scoping review, the PRISMA checklist was used, adopting the following: population - dentists; concept - effectiveness of MID; and context - continents. The following databases were used: PubMed, European Archives of Paediatric Dentistry, Scientific Electronic Library, Latin Literature American and Caribbean Association in Health Sciences, and SCOPUS. The following keywords were used in the searches: "pediatric dentistry," "atraumatic restorative treatment," "dental caries," "child health," and "glass ionomer cements" using "and" and "or" combined with "minimal intervention dentistry." Studies published before 2010 as well as theses, dissertations, opinion articles, editorials, and guidelines, were excluded from the study. A total of 160 articles were obtained, and 17 articles were screened and selected for full reading. The analysis of the studies reveals the disparity in the use of minimal intervention techniques among continents due to a lack of knowledge of these techniques or lack of confidence in changing professional approaches, thus emphasizing the need for the dissemination and teaching of MID.

Mechanical Properties and Ion Release from Fibre-Reinforced Glass Ionomer Cement.

The aim of this study was to compare the mechanical properties and ion release from a commercially available resin-modified glass ionomer cement to a formulation reinforced by the addition of short glass fibres at various percentages. Methods: Three experimental groups were prepared by adding a mass ratio of 10%, 15% and 20% of short glass fibres to the powder portion of the cement from a capsule (GC Fuji II LC), while the control group contained no fibres. Microhardness (n = 12), fracture toughness, and flexural, compressive and diametral tensile strength (n = 8) were evaluated. To study ion release, readings were obtained utilising fluoro-selective and calcium-selective electrodes after 24 h, 7 days and 30 days (n = 12). The spatial distribution of fibres within the material was evaluated through scanning electron microscopy. The data were analysed using one-way ANOVA with a Bonferroni adjustment. Results: The findings suggest that elevating fibre weight ratios to 20 wt% results in improved mechanical properties (p < 0.05) in microhardness, flexural strength, diametral tensile strength and fracture toughness. In terms of ion release, a statistically significant difference (p < 0.001) was observed between the groups at the conclusion of 24 h and 7 days, when the fluoride release was much higher in the control group. However, after 30 days, no significant distinction among the groups was identified (p > 0.05). Regarding calcium release, no statistically significant differences were observed among the groups at any of the evaluated time points (p > 0.05). SEM showed the fibres were homogeneously incorporated into the cement in all experimental groups. Conclusions: Resin-modified glass ionomer enhanced with short glass fibres at a weight loading of 20% showcased the most favourable mechanical properties while concurrently maintaining the ability to release fluoride and calcium after a 30-day period.

Adhesion of glass ionomer cements to primary dentin using a universal adhesive.

BACKGROUND: Glass ionomers are widely used for restoring carious primary teeth. However, their ability to bond to primary dentin is considered a challenge in pediatric dentistry. OBJECTIVES: The study aimed to evaluate the microshear bond strength (µSBS) of a resin-modified glass ionomer (RMGI) and a high-viscosity glass ionomer cement (Hv-GIC) to primary dentin using a universal adhesive. MATERIAL AND METHODS: Thirty human primary maxillary canines were cut in half and prepared for the µSBS test. The specimens (N = 60) were assigned to 6 groups. Three groups were defined for RMGI (FUJI II LC) and 3 groups for Hv-GIC (EQUIA Forte): with an immediately curing adhesive (G-Premio); with a delayed curing adhesive; and without an adhesive (control group). After preparing the dentin surfaces, the glass ionomers were bonded using Tygon® tubes with an internal diameter of 0.7 mm. The µSBS test was performed, and the data was analyzed using two-way analysis of variance (ANOVA) followed by Tukey's post hoc test. Additionally, the failure modes were determined using a stereomicroscope. Six specimens, one for each study group, were prepared for scanning electron microscopy (SEM) analysis to observe the glass ionomer-dentin interface. RESULTS: The type of glass ionomer did not have a significant effect on the µSBS (p = 0.305). Groups that received universal adhesive application prior to glass ionomer exhibited a significantly higher µSBS (p < 0.0001). However, there was no significant difference between the immediately curing and delayed curing groups (p = 0.157). The predominant failure mode was mixed failure. CONCLUSIONS: Higher bond strength of glass ionomers to primary teeth can be achieved by using universal adhesives, which, in addition to the proven benefits of glass ionomers, can improve their clinical success.

In vitro remineralization by various ion-releasing materials of artificially demineralized dentin: A micro-CT study.

OBJECTIVE: The aim of this study was to evaluate the remineralizing properties of ion-releasing restorative materials on pH cycling-induced carious dentin. METHODS: Fifty sound molars were freshly extracted. The occlusal surfaces were abraded using water-cooled sandpaper (800 grit). The residual crowns were embedded in self-cured acrylic resin with the flat dentin surface exposed. A mesio-distal trench was created using a calibrated 0.5 mm deep occlusal reduction burr, and artificial dentin caries were generated by pH cycling. Then, teeth were randomly assigned to five groups according to the ion-releasing material used. For each sample, micro-CT acquisitions were performed at various intervals. Remineralization was assessed by mean gray value (MGV) measurements after registration and segmentation of the region of interest with 3D Slicer software. One-way repeated-measures ANOVA followed by Tukey's post hoc test was used to investigate the difference in MGVs among the various groups. RESULTS: Only Cention Forte showed significantly increased MGVs after 4 weeks compared to demineralized dentin. MGVs were higher, but not significantly, after placement of the restorative materials, including in the resin composite control group. These results can be explained by the radiopacity of the materials. SIGNIFICANCE: Cention Forte, the material with the highest radiopacity, showed a significant increase in the MGVs of artificially carious dentin after 4 weeks. However, the study of dentin remineralization by micro-CT could be impacted by the radiopacity of the restorative materials used. The relevance of this examination for the study of dentinal remineralization should be investigated.

Organic antibacterial modifications of high-viscosity glass ionomer cement for atraumatic restorative treatment: A review.

High viscosity glass ionomer cement (HVGIC) has been employed as a restorative material for Atraumatic Restorative Treatment (ART). As residual caries persist after caries removal in ART, the antibacterial activity of HVGIC gains importance. Organic and inorganic substances with antibacterial properties have been incorporated into HVGIC over the years, and their effects on the antibacterial and physical properties have been studied. The objective of this paper is to review the various alterations made to HVGIC using organic compounds, their effect on the antibacterial activity, and the physical properties of the cement. Various in vitro investigations have been conducted by adding antiseptics, antibiotics, and naturally occurring antibacterial substances. Most of these compounds render superior antibacterial properties to HVGIC, but higher concentrations affect physical properties in a dose-dependent manner. However, some naturally occurring antibacterial substances, such as chitosan, improve the physical properties of HVGIC, as they enhance cross-linking and polysalt bridging. There is potential for clinical benefits to be gained from the addition of organic antibacterial compounds to HVGIC. In-depth research is required to determine the optimum concentration at which the antibacterial effect is maximum without affecting the physical properties of the cement.

Long term results of glass ionomer ossiculoplasty.

OBJECTIVE: To analyze and compare the early and late post-operative results of glass ionomer bone cement (GIBC) used in ossiculoplasty. METHODS: The pre-operative, early post-operative (3 months) and late post-operative (> 2 years) audiometric findings, namely the pure-tone average (PTA), bone conduction threshold (BCT) and air-bone gap (ABG) of 40 patients who underwent GIBC ossiculoplasty for different etiologies were analyzed. Early and late results were compared. Also, the patients were grouped in terms of prognostic factors and applied ossiculoplasty techniques, and the results were compared between the groups. RESULTS: There were statistically significant improvements in the pure-tone average and air-bone gap of the patients in the early post-operative period (PTA from 59.60 ± 15.95 to 40.37 ± 17.83 and ABG from 37.12 ± 11.18 to 19.78 ± 10.41, p < 0.001 for both). There were no statistically significant changes in any of the audiometric parameters in the late post-operative period (PTA from 40.37 ± 17.83 to 39.79 ± 17.91, ABG from 19.78 ± 10.41 to 19.32 ± 9.60, BCT from 17.99 ± 12.71 to 18.31 ± 13.99, p > 0.05 for all). Presence of tympanosclerosis was found to be the only prognostic factor to affect the outcome. CONCLUSION: GIBC is a safe and reliable material for ossiculoplasty, which maintains its ability to conduct sound in the long-term follow-up.

Could bulk fill glass hybrid restorative materials replace composite resins in treating permanent teeth? A randomized controlled clinical trial.

OBJECTIVE: This study aims to compare the clinical and radiographic efficacy of Equia system bulk fill glass hybrid material with composite resins in the permanent restoration of pediatric patients' permanent teeth. MATERIALS AND METHODS: The study included 44 pediatric patients aged 8-16 who applied to Necmettin Erbakan University Pediatric Dentistry Department. The groups were formed as symmetrical teeth in the same patient using the split-mouth design. The study included class I caries lesions of 144 permanent teeth. Group 1 was restored with the Equia system bulk fill glass hybrid material (Equia Forte HT + Equia Forte Coat [GC, Co, Tokyo, Japan]) (n = 72) and Group 2 with the Charisma Smart universal composite resin (Kulzer, Gmbh, Hanau, Germany) + Clearfil SE Bond (Kuraray, Noritake, Sakazu, Okayama) (n = 72). Evaluations were performed clinically and radiographically by two physicians in 2nd week, 3rd month, 6th month, and 12th month and the results were recorded. Clinical evaluation was carried out using modified-USPHS criteria. Obtained data were statistically analyzed using Kendall's W test and Cochran's Q test for the comparison within the group, and the Chi-square test for the comparison between groups. RESULTS: Among the materials utilized in the study, there was no statistically significant difference in marginal adaptation, marginal discoloration, retention, anatomical form, postoperative sensitivity, and secondary caries according (p > 0.05). Group 2 outperformed statistically significant Group 1 in terms of color match in all periods (p < 0.05). While there was no statistically significant difference in surface structure between the groups in 2nd week and 3rd month (p > 0.05), there was a statistically substantial difference in 6th, and 12th months (p < 0.05). No secondary caries or periapical lesions were found in any restorations during radiographic evaluation. CONCLUSION: After a year, the clinical performance of both Equia and composite resins was equivalent and successful in the majority of the measures against which they were evaluated. CLINICAL SIGNIFICANCE: Based on the results of the research, Equia system bulk fill glass hybrid restorations are considered a viable alternative to composite resins in class I permanent teeth restorations.

The use of rubber dam in the survival of RMGIC restorations in primary molars: a 30-month randomized controlled clinical trial

Abstract This study was a randomized controlled clinical trial with two parallel arms and the objective was to compare the survival of resin modified glass ionomer (RMGIC) restorations in primary teeth using rubber dam or cotton roll isolation after a 30-month follow-up period. Ninety-two children (mean age 6.8 ± 1.37) and 200 primary molars with occlusal or occluso-proximal cavitated dentin caries lesions were randomly assigned into two groups: cotton rolls and rubber dam. All lesions were restored using RMGIC (RIVA Light Cure) after selective caries removal. Restorative failure and lesion arrestment were evaluated by two independent, trained, and calibrated examiners through clinical and radiographic examinations. The Kaplan-Meier test was used to assess the survival of restorations and Cox regression was used to assess the association of risk factors with restorative failure. There was no significant difference in survival rates between groups (p = 0.17). Older age (HR = 2.81 [95%CI: 1.47-5.44]) and higher rate of gingival bleeding (HR = 0.47 [95%CI: 0.23-0.99]) were associated with restorative failure. No patient had painful symptoms, pulp outcomes, or radiographic changes compatible with lesion progression. The use of rubber dam isolation did not increase the survival rate of occlusal and occluso-proximal restorations using RMGIC in primary molars after 30 months of follow-up. Since the survival is not influenced by the type of isolation, the professional can safely choose the appropriate technique for each case, considering his experience and preferences, as well as those of the patient.

Effects of Ion-Releasing Materials on Dentine: Analysis of Microhardness, Appearance, and Chemical Composition.

The aim of this study was to compare the potential of standard ion-releasing materials to repair demineralized lesions with recently introduced alkasite and glass hybrid materials. Glass ionomer (GC Fuji TRIAGE), two glass hybrids (EQUIA Forte HT, Riva SC), calcium silicate cement (Biodentine) and an alkasite (Cention Forte) were tested. A total of 72 human third molars were used for sample preparation; on the dentine surface, a class-I cavity was prepared, and one half was covered with nail varnish. The teeth were subjected to a demineralization protocol, filled with the examined materials, and cut in half. The evaluation included a dentine microhardness assessment (n = 10) and SEM/EDS analysis (n = 2). The results were analyzed using SPSS 22.0 statistical software and compared using an analysis of variance and Scheffe post-hoc test. The statistical significance level was set to 0.05. Mean microhardness values (HV0.1) after 14 and 28 days were, respectively: EQUIA Forte HT (26.7 ± 1.45 and 37.74 ± 1.56), Riva Self Cure (19.66 ± 1.02 and 29.58 ± 1.18), Cention Forte (19.01 ± 1.24 and 27.93 ± 1.33), Biodentine (23.35 ± 1.23 and 29.92 ± 1.02), GC Fuji TRIAGE (25.94 ± 1.35 and 33.87 ± 5.57) and control group (15.57 ± 0.68 and 15.64 ± 0.82). The results were significantly different between most groups (p < 0.001). SEM/EDS revealed varying patterns, material deposits and distinct elemental variations. To conclude, all materials increased microhardness and affected the dentine surface appearance and chemical composition; EQUIA Forte HT demonstrated the most pronounced effects.

Short-Term Fluoride Release from Ion- Releasing Dental Materials.

Objective: To compare short-term release of fluoride ions from ion-releasing dental restorative materials. Material and methods: Seven experimental groups were prepared using the following six different materials: alkasite (Cention Forte), resin-modified glass ionomer cement (Fuji II LC), bioactive composite (ACTIVA BioACTIVE-RESTORATIVE), fluoride-containing nano-hybrid composite (Luminos UN), coat-free glass hybrid (EQUIA Forte HT), coat-applied glass hybrid (EQUIA Forte HT), and glass ionomer cement (Fuji IX). A total of 40 samples for each group (n=40) were prepared in Teflon molds (8 mm x 2 mm) and placed in polyethylene vials with 5 ml of deionized water. Fluoride release was measured after 6, 24, 48 hours, and for 5 weeks using an ion-selective electrode. The results were expressed in mg/l and the data were statistically analyzed using ANOVA. Results: Significant differences in fluoride release were observed within the first 6 hours (ANOVA p<0.001). EQUIA Forte HT had the highest release, while the other materials showed no significant differences. After 24 hours, EQUIA Forte HT (p<0.001) and Luminos UN (p<0.05) exhibited significantly higher releases, compared to other tested materials. EQUIA Forte HT maintained the highest release at 48 hours (p<0.001), followed by Cention Forte (p<0.05) and Luminos UN (p<0.05). All material pairs showed significant differences in fluoride release at 5 weeks (p<0.001). Conclusion: Coat-free EQUIA Forte HT had the overall highest fluoride release, while Cention Forte demonstrated the greatest increase over time. ACTIVA BioACTIVE-RESTORATIVE exhibited the lowest fluoride release in this study.

Remineralizing Ability of Resin Modified Glass Ionomers (RMGICs): A Systematic Review.

The selective caries removal approach leads to the need to use materials with the ability to remineralize remaining partially demineralized dentin. Among the materials proposed are resin-modified glass ionomer cements (RMGICs). The aim of this systematic review was to evaluate, based on in vitro experimental studies, whether RMGICs are suitable for remineralizing affected dentin. A systematic literature search was performed in four databases, followed by article selection, data extraction, and quality assessment. Studies assessing the remineralizing potential of RMGICs on dentin were included in our review. Studies which compared such properties between different RMGICs or with other materials were also eligible. The studies report the remineralizing ability of RMGICs, albeit with differences between different commercial products. RMGICs show a similar ability to conventional GICs to remineralize affected dentin, fulfilling the function for which they are designed. Moreover, the incorporation of additives, such as bioactive glass (BAG) or CCP-ACP, improves their remineralizing potential. The results of this review support the use of RMGICs as restorative materials after selective caries removal.

Efficacy of bioactive materials in preventing Streptococcus mutans-induced caries on enamel and dentine.

The study investigated the ability of bioactive materials used to restore enamel and dentine specimens to prevent caries. Enamel (n = 50) and dentine (n = 50) specimens were obtained from bovine incisors, prepared, and randomly allocated to one of five groups according to the restorative treatment: alkasite without adhesive system; alkasite with adhesive system; high viscosity glass ionomer cement; resin composite; no restoration; negative control group. Specimens were restored, exposed to a thermal cycling aging protocol, sterilized, and exposed to a cariogenic challenge induced by Streptococcus mutans and then submitted to surface and subsurface microhardness tests and polarized light microscopy to verify the caries lesion development in enamel or dentine surrounding the restorative materials. Data were analyzed using one-way ANOVA. In enamel and dentine, glass ionomer cement, alkasite without and with adhesive system presented a lower percentage surface microhardness loss than resin composite and negative control. Enamel subsurface microhardness presented no statistically significant differences between glass ionomer cement, alkasite without and with adhesive system. Glass ionomer cement also did not present statistically significant differences from resin composite and the negative control. In dentine, glass ionomer cement showed the highest subsurface microhardness values. In conclusion, bioactive restorative materials provide greater protection to enamel and dentine against surface caries development than resin composite.

Conservative Treatment of Dental Non-Carious Cervical Lesions: A Scoping Review.

This scoping review aims to evaluate methods of conservative reconstruction of dental enamel lesions resulting from abrasions and evaluate the effect of diode laser in reducing the symptoms of tooth sensitivity. The cementoenamel junction is more prone to substance loss because the enamel thickness is substantially decreased, resulting in a much weaker enamel-dentin bond. METHODS: Dental abrasion was examined in the mechanical cause alone. Pubmed, Scopus, and Web of Science were used to discover publications that matched our topic from 1 January 2018 to 20 March 2023. A comparison of various non-carious cervical lesion (NCCL) restoration treatments was generated mostly by mechanical considerations. RESULTS: A final number of 11 clinical trials and randomized controlled trials were included in the review for qualitative analysis. Composite resins performed well in clinical trials for the restoration of NCCLs. CONCLUSIONS: Composite, in its different forms of filling and consistency, preceded by the use of adhesives, is an efficient and effective material for the treatment of NCCLs. Diode laser use prior to NCCL restoration of teeth does not diminish restoration retention rate, may lessen hypersensitivity, and may affect restoration success.

In vitro analysis of durability of S-PRG filler-containing composite crowns for primary molar restoration.

OBJECTIVE: To evaluate the reliability, maximum principal stress, shear stress, and crack initiation of a computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite (RC) incorporating surface pre-reacted glass (S-PRG) filler for primary molar teeth. METHODS: Mandibular primary molar crowns fabricated by experimental (EB) or commercially available CAD/CAM RCs (HC) were prepared and cemented to a resinous abutment tooth using an adhesive resin cement (Cem) or a conventional glass-ionomer cement (CX). These specimens were subjected to a single compressive test (n = 5/each) and the step-stress accelerated life testing (SSALT) (n = 12/each). Data was evaluated using Weibull analyses and reliability was calculated. Afterwards, the maximum principal stress and crack initiation point of each crown was analyzed by finite element analysis. To evaluate bonding of EB and HC to dentin, microtensile bond strength (µTBS) testing was conducted using primary molar teeth (n = 10/each). RESULTS: There was no significant difference between the fracture loads of EB and HC for either cement (p > 0.05). The fracture loads of EB-CX and HC-CX were significantly lower than EB-Cem and HC-Cem (p < 0.05). The reliability at 600 N for EB-Cem was greater than that for EB-CX, HC-Cem, and HC-CX. The maximum principal stress concentrated on EB was lower than that on HC. The shear stress concentrated in the cement layer for EB-CX was higher than that for HC-CX. There was no significant difference among the µTBSs of EB-Cem, EB-CX, HC-Cem, and HC-CX (p > 0.05). SIGNIFICANCE: The crowns fabricated with the experimental CAD/CAM RC incorporating S-PRG filler yielded greater fracture loads and reliability than the crowns manufactured with commercially available CAD/CAM RC regardless of the luting materials. These findings suggest that the experimental CAD/CAM RC crown may be clinically useful for the restoration of primary molars.

Effect of incorporating silica-hydroxyapatite-silver hybrid nanoparticles into the resin-modified glass ionomer on the adhesive remnant index score and shear bond strength of orthodontic metal brackets: An in vitro study.

OBJECTIVES: This study aimed to assess the effect of addition of silica-hydroxyapatite-silver (Si-HA-Ag) hybrid nanoparticles to light-cure glass ionomer (GI) on shear bond strength (SBS) of metal brackets bonded with this adhesive and the adhesive remnant index (ARI) score. MATERIAL AND METHODS: In this in vitro experimental study, 50 sound extracted premolars were assigned to 5 groups (n=10) for orthodontic metal bracket bonding with BracePaste® composite, Fuji ORTHO™ pure resin modified GI (RMGI), and RMGI reinforced with 2wt%, 5wt% and 10wt% Si-HA-Ag nanoparticles. The SBS of brackets was measured by a universal testing machine. Debonded specimens were inspected under a stereomicroscope at×10 magnification to determine the ARI score. Data were analyzed by one-way ANOVA, Scheffe test, Chi-square test, and Fisher's exact test (alpha=0.05). RESULTS: The maximum mean SBS was recorded in BracePaste® composite followed by 2% RMGI, 0% RMGI, 5% RMGI and 10% RMGI. Only the difference between the BracePaste® composite and 10% RMGI was significant in this regard (P=0.006). The groups were not significantly different regarding the ARI scores (P=0.665). All the SBS values were within the clinically acceptable range. CONCLUSION: Addition of 2wt% and 5wt% Si-HA-Ag hybrid nanoparticles to RMGI as orthodontic adhesive caused no significant change in SBS of orthodontic metal brackets while addition of 10wt% hybrid nanoparticles significantly decreased the SBS. Nonetheless, all the SBS values were within the clinically acceptable range. Addition of hybrid nanoparticles had no significant effect on the ARI score.

A Comparison of Laser and Mechanical Surface Pretreatment Methods on Shear Bond Strength of Resin Composite to Resin-Modified Glass Ionomer.

Statement of the Problem: Dentin margins have a higher microleakage than enamel in composite restorations due to weaker bond durability. Clinically, most margins are located apical to cementoenamel junction on the dentin or cementum. Different surface preparation methods may have dissimilar effects on the shear bond strength of resin-modified glass ionomer (RMGI) to composite resin, regarding the layering technique employed in restoration of these cavities. Purpose: This study aimed to investigate the shear bond strength of RMGI to composite resin using different mechanical surface preparation methods. Materials and Method: In this in vitro study, 72 RMGI samples were prepared in six groups (n=12): control, acid etching, air abrasion with aluminum oxide (Al2O3), bur, Er: YAG laser, and Er, Cr: YSGG laser groups. Two samples from each group were randomly examined under a scanning electron microscope (SEM). A bonding layer and composite resin were applied and cured. Then the samples were subjected to 5000-cycles thermocycling procedure. The shear bond strength was then evaluated using a universal testing machine. Finally, the failed surface of the samples was evaluated under a light microscope to examine the failure mode. For the statistical analysis, one-way ANOVA and Games-Howell post hoc test was used to compare quantitative variables and chi-squared test to investigate the relationship between the failure mode and the groups. The significant level was set at 0.05. Results: The results showed significant differences between the mean of the strength variable in the groups (p< .001). The acid-etch and air abrasion groups exhibited significantly the lowest and highest values, respectively. The chi-squared test results also showed a significant relationship between the failure mode in the study groups (p= .008). Conclusion: Acid etching before completing RMGI polymerization could adversely affect shear bond strength. The air abrasion and bur methods are among the best methods to increase the shear bond strength between composite resin and RMGI. Using Er, Cr: YSGG and Er: YAG lasers could increase the bond strength results.

Remineralization Potential of Three Restorative Glass Ionomer Cements: An In Vitro Study.

The aim of this in vitro study was to evaluate the remineralizing ability of three glass ionomers on demineralized dentin with different thicknesses and time periods. Fifty third molars were obtained and were sectioned into 1-, 2-, and 3-mm thick slices (n = 36 for each thickness). The specimens were demineralized with 18% EDTA for 2 h. From the glass ionomer cements (GICs) under study (Ketac Molar Aplicap, Equia Forte, or Riva Light Cure), 1 mm was placed over each slice, set, and preserved in PBS until observation after 1, 7, 14, and 28 days after placement. For each material, thickness, and time, three samples were prepared. Using Fourier Transform Infrared Spectrometry (FTIR), apatite formation was determined on the side opposite to that on which the material had been placed. By means of Energy Dispersive Spectroscopy (EDX), the changes in the Calcium/Phosphate (Ca/P) ratio were evaluated. These changes were compared between the different materials by means of a two-way ANOVA test, considering time and dentin thickness, for a significance level of p < 0.05. Results: FTIR showed a peak at 1420 cm-1, evidencing the presence of carbonated hydroxyapatite in all the materials after 14 days, which indicates that a remineralization process occurred. Riva Light Cure showed the most homogeneous results at all depths at 28 days. The Ca/P ratio was maximum at 7 days in 2 mm of dentin for Riva Light Cure and Equia Forte HT (3.16 and 3.07; respectively) and for Ketac Molar at 14 days in 1 mm (3.67). All materials induced remineralization. Equia Forte achieved the greatest effect at 2 mm and Ketac Molar at 1 mm, whereas Riva Light Cure showed similar results at all depths. In terms of Ca/P ratio, Equia Forte and Riva Light Cure remineralized best at 2 mm, whereas for Ketac Molar, it was 1 mm. Carbonate apatite formation was higher at 24 h and 7 days for Ketac Molar, whereas it decreased at 14 days for Ketac Molar and peaked in Riva Light Cure and Equia Forte.

Effect of Bioactive Filler Addition on the Mechanical and Biological Properties of Resin-Modified Glass Ionomer.

The maintenance of affected dentin can promote the greater conservation of tooth structure. The development of materials that have properties capable of reducing the demineralizing potential and/or even helping in dental remineralization is important for conservative dentistry. This study aimed to evaluate, in vitro, the alkalizing potential, fluoride as well as calcium ion release ability, antimicrobial activity, and dentin remineralization properties of resin-modified glass ionomer cement (RMGIC) incorporated with a bioactive filler (niobium phosphate (NbG) and bioglass (45S5)). The study samples were grouped into RMGIC, NbG, and 45S5. The materials' alkalizing potential, ability to release calcium as well as fluoride ions, and antimicrobial properties concerning Streptococcus mutans UA159 biofilms were analyzed. The remineralization potential was evaluated using the Knoop microhardness test, which was performed at different depths. The alkalizing and fluoride release potential was higher for the 45S5 group (p < 0.001) over time. An increase in the microhardness of demineralized dentin was observed in the 45S5 and NbG groups (p < 0.001). No differences in biofilm formation were observed between the bioactive materials, although 45S5 exhibited lower biofilm acidogenicity at different time points (p < 0.001) and greater calcium ion release in the microbial environment. A resin-modified glass ionomer cement enriched with bioactive glasses, particularly 45S5, is a promising alternative for the treatment of demineralized dentin.