Resin-modified Glass Ionomer Cement Groups Research Articles

Comparison between Mineral Trioxide Aggregate Mixed with Water and Water-based Gel Regarding Shear Bond Strength with Resin-modified Glass Ionomer Cement and Composite

To compare between mineral trioxide aggregate (MTA) mixed with water and water-based gel regarding shear bond strength with resin-modified glass ionomer cement (RMGIC) and composite. In this study, 40 blocks of cylindrical shape were prepared with acrylic. These blocks were divided into four groups with each group consisting of 10 blocks: group-1A: MTA + distilled water + composite, group-1B: MTA + distilled water + RMGIC, group-2A: MTA + polymer + composite, and group-2B: RMGIC + MTA + polymer. After that, a universal testing machine was used for the measurement of shear bond strength. The acrylic blocks were placed under this machine. A blade with a knife-edge was used to provide a crosshead speed of 1 mm/minute. This was continued till bond of MTA in both forms (distilled water/gel) and restorative material failed. It was observed that a statistically significant difference was found between MTAw + composite and MTAg + composite resin but no statistically significant difference between MTAw + RMGIC and MTAg + RMGIC with p ≥ 0.05. It was found that a statistically significant difference was present between the RMGIC and composite groups within the same MTA type with p ≤ 0.05. It was concluded from the present study that MTA with a water-based gel has a better shear bond strength than composite resin and RMGIC materials. It has been found that MTA has different properties when it is mixed with polymer and water. Very few studies have been conducted in the past to compare MTA mixed with water and water-based gel regarding the shear bond strength with RMGIC and composite.

The effect of bacterial cellulose nanocrystals on the shear bond strength of resin modified glass ionomer cement to dentin.

BackgroundThe present study aimed to investigate the effect of bacterial cellulose nanocrystals (BCNC) on the shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) to dentin. Material and MethodsA total of 48 freshly extracted intact third molars were randomly divided into four main groups with three different concentrations (0.3%, 0.5% and 1% wt) of BCNC with RMGIC and control group without BCNC. These specimens were kept in distilled water at 37° C for 24h. Shear bond strength was examined, using the universal testing machine. Kruskal-Wallis test and Dunn`s post-hoc test were applied for analysis of data. P<0.05 was considered as the level of significance. ResultsThe addition of a 1%wt of BCNC to the RMGIC led to a significant increase in the shear bond strength (7.17 ± 2.14) compared to the control group (2.09 ± 1.80) (P=0.007). The shear bond strength was improved up to 343%. ConclusionsIt was found that the incorporation of 1% wt BCNC to the RMGICs enhanced the SBS properties of the RMGIC significantly. Modifying RMGIC with BCNC might be advantageous in terms of improving the restorative material. Key words:Bacterial cellulose nanocrystals, RMGIC, Shear bond strength.

Bond strength of Ion-releasing Restorative Materials to Sound and Caries-affected Dentin

This study evaluated the microtensile bond strength (μTBS) of ion-releasing restorative materials to sound and caries-affected dentin (CAD). 60 teeth were randomly divided into 2 groups (sound dentin, CAD) and 5 subgroups of 6 samples each: conventional glass ionomer cement (GIC), resin-modified GIC (RMGIC), glass hybrid reinforced GIC (EQ), giomer (BII), and bioactive restorative material (ACT). μTBS analyses were performed and data were analyzed statistically. The ACT group bonded to sound dentin and the BII group bonded to CAD showed the highest μTBS (p<0.05). The GIC, RMGIC, and ACT groups, showed significantly lower μTBS when bonded to CAD compared with sound dentin (p<0.05). However, in the BII group, there were no statistically significant differences between the samples bonded to sound and CAD (p>0.05). All groups except EQ that bonded to sound dentin showed predominantly adhesive failure. The use of the giomer can be recommended due to its more stable bond durability.

La evaluación de la resistencia al cizallamiento del cemento de ionómero de vidrio modificado con resina con la adición de vidrio bioactivo 45S5 utilizando dos métodos convencionales.

Introduction: There is a high prevalence of enamel caries around brackets due to the young age of the majority of orthodontic patients, and to the difficulty of plaque removal in presence of orthodontic appliances. Recently, protective agents such as bioactive glasses (BGs) were introduced to enhance remineralization and prevent demineralization of tooth structures. This study aimed to assess the shear bond strength (SBS) of resin-modified glass ionomer cement (RMGIC) with addition of 45S5 BG to enhance its remineralizing potential using two conventional methods. Material and methods: This in-vitro experimental study evaluated three groups (n=20) of orthodontic brackets bonded to enamel using Transbond XT (group 1), light-cure RMGIC (group 2) and RMGIC with BG added (group 3). Samples underwent 7000 thermal cycles and their SBS was measured. The adhesive remnant index (ARI) score was also determined. Quantitative data were analyzed using one-way ANOVA while qualitative data were analyzed using a chi-square test. Discussion: The results showed no significant difference in SBS between study groups, however the ARI scores were significantly different among the groups. The RMGIC group showed the highest ARI while RMGIC doped with BG showed the lowest ARI score. Conclusion: Addition of 30% w/v 45S5 BG to RMGIC does not cause a significant change in SBS of orthodontic brackets bonded to enamel, while resulting in less amount of luting agent remnants on the enamel surface after debonding.

Investigation of water sorption and aluminum releases from high viscosity and resin modified glass ionomer.

BackgroundHigh viscosity glass ionomer cement (HVGIC) and resin-modified glass ionomer cement (RMGIC) have recently been clinically preferred thanks to their numerous advantages. However, initial moisture contamination has a negative effect on the mechanical and physical properties of these cements. The aim of this study was in vitro of HVGICs and RMGICs, with and without surface protection, on water sorption, solubility and release of aluminum. Material and MethodsIn this study, as HVGICs; Equia Forte, IonoStar Plus, Riva Self Cure; as RMCIS, Ionolux and Riva Light Cure; and as control, Z250 universal composite was used. Equia coat, Voco varnish and Riva coat were chosen as surface protective. Water sorption and solubility levels of the samples were measured according to ISO 4049:2009. Al levels released from samples were determined by graphite furnace atomic absorption spectroscopy (GFAAS) for 7, 14 and 21 days. Statistical evaluation of the results was made using one-way variance analysis (ANOVA) and Tukey post-hoc test (p<0.05). ResultsRMGICs from restorative materials showed more water absorption than HVGICs, but no differences in solubility. Among the materials tested, the water absorption values of the HVGIC and RMGIC materials without surface protection were higher than those with the surface protection (p<0.001). ConclusionsIt was determined that the Al release of HVGIC and RMGIC groups with the surface protection were lower in all time periods than the groups without surface protection (p<0.001). The application of surface protection effectively reduced water sorption and Al release from HVGICs and RMGICs. Key words:Highly viscous glass ionomer cement, resin coating, aluminum release, water sorption, solubility.

Influence of desensitizing agents in management of noncarious cervical lesion and bonded restorations: A preliminary 12-week report.

Objectives:The primary objective of this study was to investigate the effectiveness in reducing dentin hypersensitivity in noncarious cervical lesions (NCCLs) by home-based desensitizing toothpaste (TP), in-office Gluma desensitizer application, and resin-modified glass-ionomer cement (RMGIC) restoration. The secondary objective was to evaluate the long-term outcome of the glass-ionomer cement restoration following the application of bioactive glass-containing desensitizer TP.Materials and Methods:A total of 73 patients or 151 teeth were included in the study and randomly allotted to one of the four different treatment groups. Pre- and postoperative symptom and air-blast/tactile sensitivity scores were recorded for statistical analysis. Postoperative sensitivity was analyzed at 1, 4, and 12 weeks after treatment. Nonparametric statistical tests were employed.Results:Kruskal–Wallis test noted a significant reduction in postoperative sensitivity at all time periods with the RMGIC group compared to other treatment options. Significantly higher patient dropout was observed in desensitizing TP regimen.Conclusions:This interim 12-week report on dentin hypersensitivity management of NCCLs concludes that resin-modified glass-ionomer restoration was able to achieve a significant instant reduction in sensitivity and patient satisfaction compared to other noninvasive at-home and in-office procedures.Clinical relevance:This interim 12-week report on dentin hypersensitivity management of noncarious cervical lesions concludes that resin-modified glass-ionomer restoration was able to achieve a significant reduction in sensitivity, and patient satisfaction was higher compared to other noninvasive at-home and in-office procedures.

Influence of photobio-modulation with an Er,Cr: YSGG laser on dentin adhesion bonded with bioactive and resin-modified glass ionomer cement.

One hundred and twenty extracted human molars were allocated in eight groups (n = 15) based on surface conditioning and cement type. Specimens of groups 2 and 6 were conditioned with ECL whereas, groups 3 and 7 were treated with ECL + ethylenediamine tetra acetic acid (EDTA). Specimens in groups 4 and 8 were surface conditioned by ECL + EDTA + Tetric-N-Bond, and groups 1 and 5 were considered as control (non-surface treated). Cement build-ups were performed on the surface-treated dentin with BAC (groups 1-4) and RMGIC (groups 5-8). A universal testing machine was used to measure the SBS and the mode of failure was evaluated using a stereomicroscope. Statistical analysis was performed using an analysis of variance and Tukey's post hoc test, at a significance level of p < 0.001. The highest SBS values were observed in group 8, ECL + EDTA + Tetric-N-Bond + RMGIC (21.54 ± 3.524 MPa) and the lowest SBS values were displayed by group 1, with no surface treatment and BAC application (11.99 ± 0.821 MPa). The majority of failures were found to be mixed in lased dentin-treated dentin surfaces. BAC when bonded to dentin surfaces conditioned with ECL showed lower SBS in comparison to RMGIC. Conditioning of dentin with ECL and a bonding agent (Tetric-N-bond) improved bond strength scores for BAC and RMGIC. Use of EDTA improved bond strength values when bonded to BAC and RMGIC; however, this improvement was not statistically significant.

A comparison between RMGIC and composite with acid-etch preparation or hypochlorite on the adhesion of a premolar metal bracket by testing SBS and ARI: In vitro study

A bonding material can be acceptable in orthodontics when Shear Bond Strength (SBS) is higher than 5.9Mpa. The aim of our study was to compare the bonding of a metal orthodontic bracket "in vitro" under different types of healthy enamel surface preparations and with two bonding products: the composite and the Resin Modified Glass Ionomer Cement (RMGIC). Premolars preserved in 1% thymol water were bonded on their vestibular and palatal/lingual surfaces with different techniques of bonding and surface preparation: Group 1: Etching+Bonding+Composite, Group 2: Etching+Fuji Ortho LC, Group 3: V-prep+Fuji Ortho LC, Group 4: V-prep+Fuji Ortho LC+Thermocycling. The SBS was measured in Newton on the universal testing machine and the sample was observed under an optical microscope with 10-fold magnification to note the adhesive remnant index score (ARI), before and after thermocycling. 120 premolars were used in this study. RMGIC bonding was significantly increased when the surface was prepared at V-prep (P<0.001). In these conditions, RMGIC bonding on the buccal surface was similar to that of the composite and superior on the palatal/lingual surface (P=1). After 2 years of aging using a thermocycling machine for simulation, RMGIC bonding significantly decreased (P<0.001). The ARI score was significantly lower for the RMGIC group than the composite group (P<0.001). RMGIC bonding with V-prep preparation is recommended for palatal/lingual surfaces and for hard-to-dry surfaces. For vestibular surfaces, studies are still needed to recommend bonding with RMGIC instead of composite.

Effect of dentin contamination with two hemostatic agents on bond strength of resin-modified glass ionomer cement with different conditioning

This study evaluated the effect of two hemostatic agents on bond strength of resin-modified glass ionomer cement (RMGIC) to root dentin after using different pretreatment solutions compared to resin composite with a 2-step self-etch adhesive. Dentin specimens were either uncontaminated or contaminated with a ferric sulphate or aluminum chloride astringent, RMGIC was applied after conditioning with; Cavity Conditioner, Self Conditioner or Clearfil SE Primer, while a resin composite was bonded using Clearfil SE Bond. Microtensile bond strength (μTBS) values and failure modes were determined. Two-way ANOVA revealed that hemostatic agents did not significantly affect the RMGIC bond strength with any conditioning material (p>0.05). SE Primer pretreatment provided the highest μTBS values among RMGIC groups. For the resin composite, ferric sulphate astringent significantly reduced μTBS value (p≤0.001). Scanning electron micrographs of representative dentin surfaces contaminated with the hemostatic agents showed effects on smear layer removal and dentinal tubule occlusion.

Effects of Different Remineralisation Agents and Adhesives Around Orthodontic Brackets: Is There a Relationship Between Remineralisation and Shear Bond Strength?

The aim of this in-vitro study was to evaluate the effects of different remineralisation agents and adhesives on the remineralisation of white spot lesions (WSL) using quantitative light-induced fluorescence (QLF) and the shear bond strength (SBS) of brackets. One hundred fifty premolars were bonded with Transbond XT and resin-modified glass-ionomer cement (RMGIC). WSL were created using a demineralization solution and an APF gel, Tooth Mousse (TM) and Duraphat were applied for remineralisation. WSL were evaluated using QLF and SBS of brackets and tested using an Instron testing machine. Paired-samples t-test, independent-samples t-test and one-way ANOVA were used for comparisons of the ∆F, area and SBS. Post-hoc tests were performed using Tukey's test. In the Transbond group, all remineralisation agents provided remineralisation, with Duraphat producing greater improvement. In terms of lesion area, the positive control and APF gel group values were close to each other, and a statistically significant improvement was observed in the TM and Duraphat groups' areas. In the RMGIC group, with TM application, the ΔF value was statistically significantly higher; area differences between the APF and TM groups were not statistically significant. The Transbond group showed greater SBS than did RMGIC, and in the Transbond group, Duraphat had the highest SBS value. In bonding with Transbond, the Duraphat group demonstrated greater improvement than other remineralisation agents. In the RMGIC group, the best remineralisation was obtained by TM. The Transbond XT and Duraphat combination provided the highest SBS values.

Shear Bond Strength of Self-Adhesive Flowable Composite, Conventional Flowable Composite and Resin-Modified Glass Ionomer Cement to Primary Dentin.

Objectives:This study aimed to compare the shear bond strength (SBS) of self-adhesive and conventional flowable composites and resin-modified glass-ionomer cement (RMGIC) to primary dentin.Materials and Methods:In this in vitro, experimental study, the buccal surface of 48 primary canine and first molar teeth was longitudinally sectioned to expose dentin. The teeth were randomly divided into three groups (n=16) of 37.5% phosphoric acid+ OptiBond+ Premise Flow composite (group 1), Vertise Flow composite (group 2) and RMGIC (group 3). A plastic cylindrical mold was placed on the exposed dentin and filled with restorative materials. The samples were then immersed in distilled water at 37°C for 24 hours, subjected to 1000 thermal cycles between 5–55°C and underwent SBS test. The mode of failure was determined under a stereomicroscope. Data were analyzed using one-way ANOVA and Tukey’s test.Results:A significant difference was noted in SBS of the groups (P<0.05). The SBS of conventional flowable composite was significantly higher that of RMGIC and self-adhesive flowable composite (P<0.05). The difference in SBS of RMGIC and self-adhesive flowable composite was not significant (P>0.05). Failure at the dentin-restoration interface (adhesive failure) had the highest frequency in groups 1 and 2. The frequency of adhesive failure was 100% in group 3.Conclusion:Within the limitations of this study, the conventional flowable composite yielded the highest SBS to primary dentin. Self-adhesive flowable composite and RMGIC showed the lowest SBS with no significant difference with each other.

Microhardness of coronal dentin adjacent to resin-modified glass ionomer and compomer in Class V restorations

Aims: The objective of this in vitro study was to compare the microhardness values of coronal dentin adjacent to resin-modified glass-ionomer cement (RMGIC) and compomer. Materials and Methods: Standardized Class V preparation was performed for 30 extracted human permanent molars affected by Class V caries. The samples were divided into three groups as follows: specimens before restoration (Group 1) (n = 10), samples restored using RMGIC (Group 2) (n = 10), and specimens treated with compomer (Group 3) (n = 10). Dentinal discs with 2-mm diameter were obtained after embedment into acrylic resin. Vickers microhardness measurements were performed using a digital microhardness tester (Zwick/Roell) immediately after the 10th, 20th, and 30th day by applying a load of 25 g for 15 s at a distance of 100, 200, and 300 μm from the cavity floor. Statistical Analysis Used: One-way analysis of variance and post hoc Tukey tests (P

Clinical Effectiveness of a Resin-modified Glass Ionomer Cement and a Mild One-step Self-etch Adhesive Applied Actively and Passively in Noncarious Cervical Lesions: An 18-Month Clinical Trial

To evaluate the clinical effectiveness of two methods of application of a mild one-step self-etch adhesive and composite resin as compared with a resin-modified glass ionomer cement (RMGIC) control restoration in noncarious cervical lesions (NCCLs). A total of 294 restorations were placed in 56 patients, 98 in each one of the following groups: 1) G-Bond active application combined with Solare-X composite resin (A-1SEA), 2) G-Bond passive application combined with Solare-X composite resin (P-1SEA), and 3) GC II LC RMGIC. The restorations were evaluated at baseline and after six, 12, and 18 months according to the FDI criteria for fractures/retention, marginal adaptation, marginal staining, postoperative sensitivity, and secondary caries. Cumulative failure rates were calculated for each criterion at each recall period. The effect of adhesive, method of application, and recall period were assessed. The Kruskal-Wallis test for intergroup comparison and Friedman and Wilcoxon signed ranks tests for intragroup comparison were used for each criterion ( α=0.05). The retention rates at 18 months were 93.26% for the A-1SEA group, 86.21% for the P-1SEA group, and 90.91% for the RMGIC group. The active application improved the retention rates compared with the passive application of mild one-step self-etch adhesive; however, no statistically significant difference was observed between the groups. Marginal staining was observed in 13 restorations (1 in A-1SEA, 4 in P-1SEA, and 8 in RMGIC) with no significant difference between the groups. The RMGIC group showed a significant increase in marginal staining at 12 and 18 months from the baseline. There was no significant difference between the groups for marginal adaptation, secondary caries, or postoperative sensitivity. Within the limitations of the study, we can conclude that mild one-step self-etch adhesive followed by a resin composite restoration can be an alternative to RMGIC with similar retention and improved esthetics in restoration of NCCLs. Agitation could possibly benefit the clinical performance of mild one-step self-etch adhesives, but this study did not confirm that the observed benefit was statistically significant.

Evaluation of Mineral Trioxide Aggregate, Resin-modified Glass Ionomer Cements, and Composite as a Coronal Barrier: An in vitro Microbiological Study

The purpose of the study is to evaluate the bacterial micro-leakage of three different materials, mineral trioxide aggregate (MTA), resin-modified glass ionomer cement (RMGIC), and flowable composite, as a coronal barrier against Enterococcus faecalis. A total of 100 human extracted single-rooted teeth were selected. Access opening done, working length determined, and canals were cleaned and shaped with ProTaper F3 and obturated with AH26 and gutta-percha (GP) using lateral condensation technique. Samples were divided into three experimental and two control groups. Approximately 3 mm GP was removed from the coronal orifice and restored with one of the test materials. Teeth were suspended in glass tubes containing brain heart infusion (BHI) broth and equipped with microcaps, which were used to check bacterial leakage. A 24-hour broth of E. faecalis was placed in the pulp chamber. Tubes were incubated and checked for turbidity for 90 days. Data were analyzed using chi-squared test between the test and control groups and Fisher test between the test groups. Significantly lesser number of samples turned turbid in the RMGIC group followed by MTA group and the maximum number of samples turned turbid in the flowable composite group. The RMGIC is a better coronal sealer, followed by MTA and flowable composite. Coronal sealing ability of RMGIC is more promising in comparison with the other agents.

Microhardness and SEM-EDX Analysis of Permanent Enamel Surface Adjacent to Fluoride-releasing Restorative Materials Under Severe Cariogenic Challenges.

In this study, the protective effects of restorative materials with fluoride content, resin-modified glass-ionomer cement (RMGIC), giomer, and glass carbomer against artificial initial caries lesions in a simulated highly cariogenic oral environment were evaluated. Considering the reported recharging abilities of these restorative materials, fluoridated toothpaste was applied to some groups, in which the anti-demineralising effect was also evaluated. Two enamel blocks were produced from each of 60 sound permanent molars. Sixty specimens were used for microhardness analysis, and the rest were used for SEM-EDX analysis. Enamel specimens were randomly assigned to three groups according to the restorative material: A = resin-modified glass-ionomer cement; B = giomer; C = glass carbomer. Artificial initial caries lesions were created using demineralising solutions, after which specimens were exposed to in vitro pH cycling simulating a highly cariogenic oral environment. Microhardness and mineral analyses were performed on the enamel surrounding the restorative materials at three different times during the experiment: at the beginning of the experiment, then after the creation of the artificial early caries lesions, and finally after pH cycling. Microhardness and SEM-EDX results mostly confirmed each other. RMGIC and glass carbomer groups with added fluoride toothpaste showed statitsically significantly better anti-demineralising effects in comparison to other groups. Neither of the giomer groups performed as well as RMGIC or glass carbomer. Because of the similarity between the demineralisation inhibitory activity of glass carbomer and RMGIC, glass carbomer may be preferred as a restorative material in paediatric dentistry.

BONDING ABILITY OF DIFFERENT LINERS TO BULK-FILL RESIN COMPOSITE USING SILANE-CONTAINING ADHESIVE

Aims: To compare and evaluate the bonding ability of bulk-fill resin composite (RC) to four different liners: Biodentine (BD), TheraCal (TLC) - a novel resin-modified calcium silicate cement, resin-modified glass ionomer cement (RMGIC) and conventional glass ionomer cement (GIC) using a universal silane-containing adhesive and characterizing their failure modes.Materials and Methods: Forty extracted intact human premolars with occlusal cavity (4-mm diameter and 2-mm height) were mounted in acrylic blocks and divided into four groups of (n=10 samples) each based on the liner used as group I; (BD), group II; (TLC), group III; (RMGIC) and Group IV; (GIC). Bulk-fill composite buildup of 3 mm diameter and 5 mm height was then bonded to each sample using universal adhesive. Shear bond strength (SBS) analysis was performed using materials testing machine at a cross-head speed of 0.5 mm/min. Statistical Analysis: Statistical analysis was performed with one-way analysis of variance (ANOVA) and Tukey’s post hoc test for numerical data while chi square test for categorical one. Results: One-way analysis with ANOVA revealed significant difference in bond strength values between the different groups (p<0.001). The observed modes of failure were predominantly cohesive in Biodentine, TheraCal and GIC groups while RMGIC showed majority of mixed and minority adhesive failures.Conclusions: Biodentine demonstrated lower bond strength values when immediately bonded to bulk-fill resin composite compared with RMGIC, TheraCal and GIC groups

The effects of different restorative materials on the detection of approximal caries in cone-beam computed tomography scans with and without metal artifact reduction mode

The aim of this study was to investigate the influence of artifacts produced by different restorative materials on the detection of approximal caries in cone-beam computed tomography (CBCT) scans with and without the application of an artifact-reduction (AR) option. Ninety-eight noncavitated premolar and molar teeth were placed with approximal contacts consisting of 2 sound or carious teeth and 1 mesial-occlusal-distal restored tooth with resin-modified glass-ionomer cement (RMGIC), amalgam, composite, ceramic-based composite (CBC), or computer-aided design-computer-aided manufacturing (CAD-CAM) zirconia materials in between. The teeth were scanned with a CBCT system with and without the AR option. Images were evaluated by 2 observers. The teeth were histologically evaluated, and sensitivity, specificity, and areas under the receiver operating characteristic (ROC) curve were calculated according to the appropriate threshold. Specificity and sensitivity values for contact surfaces ranged from 0-48.39 and 82.93-98.40, respectively. The AR option affected (P<.05) approximal caries detection of the amalgam, composite, CAD-CAM, and CBC groups in contact surfaces and composite and RMGIC groups in noncontact surfaces. Artifacts produced by different restorative materials could affect approximal caries detection in CBCT scans. Use of the AR option with CBCT scans increases the accuracy of approximal caries detection.

Comparative Assessment of in Vitro Effect of Three Fluoride Releasing Agents on Enamel Demineralization around Orthodontic Brackets

Background: White spot lesion considered as irreversible tooth demineralization presenting challenge to orthodontists during treatment schedules, fluoride was the most successfully used measure to overcome this challenge. Materials and method: A total of forty sound human permanent premolars were used in the present study and categorized into four groups, in one group the teeth were bonded with stainless steel brackets using Resin-modified glass ionomer cement (RMGIC) and the other three groups the teeth were bonded with light cured composite Resilience® (Ortho technology Co., USA). Group A; Acidulated phosphate fluoride (APF) topical gel (Mfg by DEEPAK PRODUCTS, INC, USA), fluoride ion 1.23% applied on examine area for four minute. Group B; RMGIC (GC Fuji Ortho LC, GC Corporation/Japan) used as bracket adhesive. Group C; Stannous and sodium phosphate fluoride gel yielding 0.72% fluoride ion (Mfg. for: dental resources DS-8) (0.4% Stannous fluoride, 1% sodium fluoride), was applied daily through the experimental study. D; the control group represents the conventional bonding procedure with no preventive method. The entire labial surfaces except 2 mm gingival to the bracket were isolated by acid resistance varnish. All the teeth were subjected individually during 30 days in to acid challenge cycle. After longitudinal sectioning of the teeth by using a hard-tissue microtome, the depth of the artificial lesion was estimated by taking the average of three penetration depths at the lesion centre under stereomicroscope. Also the enamel surface was classified according to acid etch pattern. Comparisons of the average caries penetration of the groups were submitted to ANOVA and LSD tests. The statistical significance level was set at p ≤ 0.05. Results: The results revealed that there were statistically significant differences among the tested groups. With different caries reduction abilities, APF group showed 14%, RMGIC Group 49%, group Stannous and sodium phosphate fluoride 39% depth reduction compared to the control group. Conclusions: While all the groups showed caries reduction by different fluoride agents used in this study, the less average lesion depth was found at group B making the RMGIG the best caries fighting fluoride measure.

Evaluation of Shear Bond Strength of Resin Reinforced Glass Ionomer Cement Modified by Nano-hydroxyapatite on Ceramic Bracket Debonding Using Full-dimension Wire

Aim: Using fluoride releasing materials such as Glass Ionomer Cement (GIC), can control the demineralization around brackets. In this study, the shear bond strength of resin reinforced GIC modified by Nano-hydroxyapatite (NHA) on ceramic bracket debonding is evaluated. In addition, using full-dimension wire for safe debonding is also examined. Study Design: Original article. Place and Duration of Study: Department of Dentistry, Shahed University, Tehran, IRAN, June 2013. Methods and Material: 80 extracted human premolars received from a clinic were partitioned into 4 groups. Bonding materials used in each group was as follows: Group 1: Transbond XT as a control group, Group 2: Resin Modified GIC (RMGIC), Group 3: RMGIC added 5% NHA and Group 4: RMGIC added 10% NHA. In all groups the enamel was etched with 37% phosphoric acid and ceramic brackets were used. Each group halved into 2 subgroups which just in one of them full dimension wire was employed at the time of debonding. The shear bond strength, Adhesive Remnant Index (ARI) and bracket failure figures were collected for each group. The data was latter analyzed using one-way Analysis Of Variance (ANOVA), Tukey’s HSD (Honestly Significant Difference) Post-hoc Original Research Article Article Annual Research & Review in Biology, 4(10): 1578-1586, 2014 1579 and Kruskal Wallis Test methods. Results: According to ANOVA, RMGIC added 5% NHA has no negative effect while adding 10% NHA lowered the shear bond strength significantly. No bracket failure occurred at debonding, either using or not using full dimension wire. ARI for RMGIC groups were more cohesive than the control group. Conclusion: RMGIC containing 5% NHA contributes bond strength similar to composite resins, in bonding ceramic brackets, while its known demineralization resistance is a favor.

In vitro and in vivo investigation of the biological and mechanical behaviour of resin-modified glass-ionomer cement containing chlorhexidine

ObjectivesTo evaluate: (1) the in vitro antibacterial, cytotoxic and mechanical properties of a resin-modified glass ionomer cement (RMGIC) containing different concentrations of chlorhexidine (CHX) and (2) the in vivo microbiologic action of the best concentration of CHX associated with the RMGIC applied on remaining dentine after indirect pulp treatment (IPT). MethodsFor the in vitro studies, RMGIC was associated with 0.2, 0.5, 1.25 and 2.5% CHX. Microbiologic evaluation consisted of an agar diffusion test on cariogenic bacteria for 24h. Odontoblast-like cell metabolism and morphology analyses measured the cytotoxic effects of the RMGIC groups after 24h. The same groups were submitted to compressive and diametral tensile strength. The in vivo treatment consisted of IPT using an RMGIC associated with the best CHX concentration. Clinical and microbiologic evaluations were performed before and after 3 months. ResultsThe use of 1.25% CHX significantly improved the antibacterial effects of the evaluated RMGIC, without causing any detrimental effects to the odontoblast-like cells and on the mechanical properties. This RMGIC and CHX combination completely eliminated mutans streptococci after 3 months of IPT. ConclusionThe RMGIC and 1.25% CHX mixture showed great biological and mechanical behaviour and could be a good treatment against caries progression. Clinical significanceThe association of CHX with a liner RMGIC opens a new perspective for arresting residual caries after IPT.