Light-cured Glass Ionomer Cement Research Articles

The effect of cusp capping with composite resin on fracture resistance of premolars with prepared endodontic access cavities: An in vitro study

Introduction: The purpose of this study was to evaluate the effect of remaining dentinal wall thickness and the effect of remaining cusp height of endodontically treated premolars when restored with composite resin. Materials and Methods: Ninety premolars were divided into 4 test groups (n = 20) and 2 control groups (n = 5). In all groups, except the negative control group (sound teeth), standardized endodontic access cavities were prepared, pulp extirpated, mesioocclusodistal (MOD) cavities prepared and access sealed with Light Cure Glass Ionomer Cement (LC GIC). Test groups were divided as:- Cusp reduction for Groups I and II- 2.5 mm and for Groups III and IV- 1.5 mm. Dentinal wall thickness for Groups I and III- 1-1.5 mm and Groups II and IV- 2-3 mm. The groups were further subdivided into Subgroup A, restored with P60 and Subgroup B, restored with Herculite Precis. Positive control- only access cavity with no cusp reduction and restoration. Fracture resistance was assessed using Universal Testing Machine (UTM). Results: Highest fracture resistance was demonstrated by Group VI and least by Group V. Groups VI, II and I, showed statistically insignificant difference for both the composites (P > 0.05). Groups III and IV showed statistically significant difference only for Subgroup B. Conclusion: When the cusp reduction was 2.5 mm, dentinal wall thickness had no effect on the fracture resistance, for both the composites. When the cusp reduction was 1.5 mm and the remaining dentinal thickness was 1-1.5 mm, Herculite Precis showed inferior results to P60.

Comparative evaluation of sealing ability of light cure glass ionomer cement and light cure composite as coronal sealing material: An in vitro study

Aim: To compare and evaluate the sealing ability of light cure composite and light cure GIC as coronal sealing materials. Materials and Methods: 30 extracted human teeth were divided into three experimental groups of 10 teeth each. The teeth in group I are obturated without coronal seal, teeth in group II are obturated with light cure GIC (3M ESPE VITREMER) as coronal seal and teeth in group III are obturated with light cure composite(3M ESPE filtek z250) as coronal seal, after removing 2mm of coronal gutta percha. These teeth (crown portion) are then suspended in methylene blue, sealed and kept for 72 hours, to observe the amount of dye penetration. After 72 hours teeth were removed, washed under running water, dried and sectioned longitudinally, separating buccal and lingual halves. The linear extent of dye penetration was measured from cavosurface margin of the access cavity to the most apical extent of dye penetration point. The length from the cavosurface margin to the apex of the tooth was also measured and percentage linear micro leakage was estimated. Statistical Analysis: Data was statistically analyzed using one-way ANOVA followed by Post-Hoc Multiple comparison (Bonferroni). Results: In the present study specimens in group I showed the maximum percentage of linear microleakage of 31.51 percent. The specimens in group II showed the minimal amount of linear micro leakage of 6.49 percent. Conclusion: It can be concluded coronal seal reduces the micro leakage, and light cure GIC has better coronal sealing ability.

Evaluation of the leakage of bleaching materials through different bases into the root canal filling: an invitro study

AIM: The purpose of this study was to evaluate the leakage of bleaching agents through 3 different bases into the obturated pulp space and dentinal tubules in intra coronal bleaching. MATERIAL AND METHODS: Fifty-five freshly extracted, intact non-carious single rooted teeth were collected and stored in formalin until used. The specimen divided into experimental and control group. Experimental group were further subdivided into 3 subgroups on the base of cervical base materials. Group I was Type II GIC, Group II was Fuji II LC and Group III was Hybrid composite. The control groups was divides into negative group (received the bleaching agent and received complete external coating including access cavity) and positive control group (did not receive any external coating). The obturated pulp space were removed at a level of 3 mm below the cemento enamel junction and filled with dry cotton pellets and temporized with temporary cement, stored at ± 37°C and 100% relative humidity for five days, the bleaching material were placed in the pulp chamber (a paste of sodium perborate i.e. 0.15g and 30% hydrogen peroxide 0.05ml), and then stored for 3 days in an incubator. Later on the teeth were immersed in India ink dye and stored at ± 37°C and 100% relative humidity for 5 days. Specimens were examined under binocular microscope with a stage micrometer to analyze the degree of dye penetration. RESULTS: The minimal leakage values were observed with type II glass ionomer cement followed by light cure glass ionomer cement and lastly by hybrid composite. CONCLUSION: The present invitro investigation evaluated the microleakage observed with different cervical base materials during non-vital bleaching procedures.

Modification of resin modified glass ionomer cement by addition of bioactive glass nanoparticles.

In the present study, sol-gel derived nanoparticle calcium silicate bioactive glass was added to the resin-modified light cure glass-ionomer cement to assess the influence of additional bioactive glass nanoparticles on the mechanical and biological properties of resin-modified glass-ionomer cement. The fabricated bioactive glass nanoparticles added resin-modified glass-ionomer cements (GICs) were immersed in the phosphate buffer solution for 28 days to mimic real condition for the mechanical properties. Resin-modified GICs containing 3, 5 and 10 % bioactive glass nanoparticles improved the flexural strength compared to the resin-modified glass-ionomer cement and the samples containing 15 and 20 % bioactive glass nanoparticles before and after immersing in the phosphate buffer solution. Characterization of the samples successfully expressed the cause of the critical condition for mechanical properties. Cell study clarified that resin-modified glass-ionomer cement with high concentrations of bioactive glass nanoparticles has higher cell viability and better cell morphology compare to control groups. The results for mechanical properties and toxicity approved that the considering in selection of an optimum condition would have been a more satisfying conclusion for this study.

Influence of chemical degradation and abrasion on surface properties of nanorestorative materials

Aim: The aim of this in vitro study was to investigate the synergistic effect of chemical degradation (erosion) and three-body abrasion (mechanical degradation) on the surface roughness (Ra) and hardness (KHN) of two nanorestorative materials and two conventional materials. Methods: Discshaped specimens (5 mm in diameter, 2 mm thick) of Filtek Z350TM and TPH SpectrumTM composites and Ketac NanoTM and VitremerTM light-curing glass ionomer cements, nanomaterials and conventional materials were prepared according to the manufacturer’s instructions. After 24 h, polishing procedures were performed and initial measurements of Ra and KHN were taken in all specimens. The specimens were divided into 12 groups (n = 10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola®. After 30 days of storage, the specimens were submitted to mechanical degradation and re-evaluated for Ra and KHN. Data were tested for significant differences by repeated-measure three-way ANOVA and Tukey’s tests (p<0.05). Results: Erosion and abrasion wear significantly decreased hardness of all materials. Only Filtek Z350 roughness, however, was not affected by erosion and abrasion. All materials showed a significant increase in surface roughness after erosion and abrasion, except for Filtek Z350. After chemical and mechanical degradation, the KHN of all samples had decreased significantly. After mechanical degradation, the acidic drinks (Coca-Cola® and orange juice) were more aggressive than artificial saliva to all materials. Conclusions: A synergistic effect was observed by the increase in roughness for all materials, except for Filtek Z350; hardness values decrease for all materials, regardless of whether they were nanofilled or not. The RMGICs were more susceptible to degradation than the composites, considering both hardness and roughness surface parameters.

Effect of alcohol containing and alcohol free mouth rinses on microhardness of three esthetic restorative materials

Abstract Introduction Daily application of mouth rinses has been recommended for the prevention and control of caries and periodontal disease. Aims &amp; Objectives The aim of this study was to evaluate the effect of alcohol-containing and alcohol-free mouth rinses on the microhardness of three restorative materials – resin composite (Filtek Z350XT), light cure glass ionomer cement (Vitremer) and conventional restorative glass ionomer cement (GC Fuji II). Methods Twenty samples of each restorative material were fabricated and their microhardness values were checked at 100g load and 15 seconds dwell time. Ten samples of each restorative material were stored in alcohol containing mouth rinse (Listerine) and ten samples each were stored in alcohol free mouth rinse (Hiora) for 12 hours. At the end of the test period microhardness was measured with a Vickers microhardness tester. Results Alcohol containing mouth rinses reduced the microhardness values of composite and light cure glass ionomer significantly more than alcohol free mouth rinses. Reduction in the microhardness value of conventional restorative glass ionomer cement was similar for both alcohol containing and alcohol free mouth rinses. Conclusion Both mouth rinses showed reduction in microhardness values of all three restorative materials, with more reduction caused due to alcohol containing mouth rinses in composite and light cure glass ionomer. How to cite this article Vasundhara S, Rucha N. Effect of alcohol containing and alcohol free mouth rinses on microhardness of three esthetic restorative materials. CODS J Dent 2014;6;5-8

Physical properties of root cementum: Part 24. Root resorption of the first premolars after 4 weeks of occlusal trauma

In orthodontics, adding restorative materials on occlusal or lingual surfaces is a common method to create a mini-biteplane to increase patients' vertical dimension temporarily to facilitate several treatment procedures. However, this method transmits excessive occlusal forces through the periodontal ligament and causes trauma. In this prospective randomized clinical trial, we measured and compared quantitatively the volumes of root resorption after 4 weeks of occlusal trauma. Forty-eight maxillary and mandibular first premolars of 12 patients (6 girls, 6 boys) comprised the sample for this study. One side of each patient was randomly selected as the control. On the contralateral side, a light-cured glass ionomer cement (Transbond Plus Light Cure Band Adhesive; 3M Unitek, Monrovia, Calif) was bonded onto the occlusal surface of the mandibular first premolar so that the cement was in contact with the maxillary first premolar. After 4 weeks, both first premolars were extracted. Each sample was imaged using a microcomputed tomography system (1172; SkyScan, Aartselaar, Belgium) and analyzed with specially designed software for volumetric measurements of resorption craters. Furthermore, pain was evaluated with a visual analog scale for 7 days. There were significant differences in the amounts of root resorption between the control and the experimentally traumatized teeth. No significant difference among the buccal, lingual, mesial, and distal surfaces was found in either jaw. Furthermore, no significant difference existed in the amount of root resorption among the cervical, middle, and apical thirds of both jaws. There was no correlation between age, sex, volume of the root resorption craters, and pain. Restorative buildups, used to increase the vertical dimension by 2 mm for 4 weeks, caused root resorption along the sides of the teeth during the active bite-increase period.

Preparation and evaluation of a novel star-shaped polyacid-constructed dental glass–ionomer system

ObjectiveThe objective of this study was to synthesize and characterize novel star-shaped poly(acrylic acid-co-itaconic acid)s via chain-transfer radical polymerization technique, use these polyacids to formulate the resin-modified glass–ionomer cements, and evaluate the mechanical strengths of the formed cements Materials and methodsThe star-shaped poly(acrylic acid-co-itaconic acid)s were synthesized via a chain-transfer radical polymerization reaction using a newly synthesized star-shaped chain-transfer agent. The effects of MW, GM-tethering ratio, P/L ratio and aging on the compressive properties of the formed experimental cements were studied. Compressive, diametral tensile as well as flexural strengths were evaluated and compared to those of Fuji II and Fuji II LC cements. ResultsThe star-shaped polyacids showed significantly lower viscosities in water as compared to their linear counterparts. The cements formulated with these novel polyacids showed significantly improved mechanical strengths i.e., 49% in yield strength, 41% in modulus, 25% in CS, 20% in DTS and 36% in FS, higher than commercial Fuji II LC. After aging in water for 30 days, the compressive strengths of the experimental cements were significantly changed with an increase of 29% in YS, 19% in modulus as well as 23% in CS and a decrease of 5% in toughness, indicating that aging in water enhances the salt-bridge formation and increases brittleness. ConclusionsA novel light-cured glass–ionomer cement system composed of the star-shaped poly(carboxylic acid)s has been developed via a cost-effective and time-efficient chain-transfer radical polymerization.

Intraorifice sealing ability of different materials in endodontically treated teeth: An in vitro study.

Background:Microbial contamination of the pulp space is one of the major factors associated with endodontic failure. Thus, in addition to a three dimentional apical filling a coronal seal for root canal fillings has been recommended.Aim:The present study was conducted to evaluate and compare the intra-orifice sealing ability of three experimental materials after obturation of the root canal system.Materials and Methods:Fourty single rooted mandibular premolars were decoronated, cleaned, shaped and obturated. Gutta-percha was removed to the depth of 3.5 mm from the orifice with a heated plugger. Ten specimens each were sealed with Light Cure Glass Ionomer Cement (LCGIC), Flowable Composite (Tetric N-Flow), and Light Cure Glass Ionomer Cement with Flowable Composite in Sandwich Technique along with a positive control respectively and roots submerged in Rhodamine-B dye in vacuum for one week. Specimens were longitudinally sectioned and leakage measured using a 10X stereomicroscope and graded for depth of leakage.Results:According to the results of the present study LC GIC + Tetric N Flow demonstrated significantly better seal (P < 0.01) than LC GIC. However there was no statistically significant difference in leakage (P > 0.01) between Tetric N-Flow and LCGIC+Tetric N-Flow groups.Conclusion:In the current study LCGIC+Tetric N-Flow was found to be superior over other experimental materials as intra-orifice barriers.

An in vitro study to evaluate the effects of addition of zinc oxide to an orthodontic bonding agent.

Objective:The objective of this study is to test the antimicrobial effect of zinc oxide when incorporated into an orthodontic bonding material and to check the effect of addition of zinc oxide on the shear bond strength of the bonding material.Materials and Methods:Zinc oxide was added to a resin modified light cure glass ionomer cement (GIC) (Fuji Ortho LC GC America, Alsip, Ill) to make modified bonding agent containing 13% and 23.1% ZnO and the antimicrobial assay was done using agar disc diffusion method. Discs of the modified bonding agent were prepared and a culture of Streptococcus mutans mixed with soft agar was poured over it and incubated at 38°C for 48 h and zones of inhibition were measured. The test was repeated after a month to check the antimicrobial effect. In addition shear bond strength of the brackets bonded with the modified bonding agent was tested.Results:The agar disc showed zones of inhibition around the modified bonding agent and the antimicrobial activity was more when the concentration of ZnO was increased. The antimicrobial effect was present even after a month. The shear bond strength decreased as the concentration of ZnO increased.Conclusion:The incorporation of ZnO into a resin modified light cure GIC (Fuji Ortho LC GC America, Alsip, Ill) added antimicrobial property to the original compound.

Effect of mineral trioxide aggregate as a direct pulp capping agent in cariously exposed permanent teeth

Aims and Objectives: To evaluate the effectiveness of mineral trioxide aggregate (MTA) when used as a pulp capping agent in permanent teeth with carious exposure (≤1mm) after root formation is completed. Materials and Methods: Clinical follow-up was performed on 32 mandibular molars with deep occlusal caries, in patients in the age group range of 18 to 42 years. Carious pulpal exposures were treated by direct pulp capping with MTA, followed by a base of light cure glass ionomer cement and restored with amalgam. Clinical and radiographic examinations were carried out periodically at 1, 3, 6, 9, 12, 18 and 24 months. Results: After 24 months clinical and radiographic follow-up, it was found that 25 (out of 32) patients had successful outcome. However, two patients failed to return for evaluation after permanent restoration, and five patients exhibited clinical failure. Conclusions: Mineral trioxide aggregate was found to be an effective material when used for direct pulp capping in permanent teeth. However, further investigations with a larger sample size are needed to support these findings.

Influence of Chemical Degradation on the Surface Properties of Nano Restorative Materials

The aim of this in vitro study was to investigate the effect of chemical degradation on the surface roughness (Ra) and hardness (Knoop hardness number [KHN]) of nano restorative materials. Disc-shaped specimens (5-mm diameter; 2-mm thick) of Filtek Z350 and TPH Spectrum composites and the Vitremer and Ketac Nano light-curing glass ionomer cements were prepared according to the manufacturers' instructions. After 24 hours, polishing procedures were performed and initial measurements of Ra and KHN were taken. The specimens were divided into 12 groups (n=10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola. After 30 days of storage, the specimens were reevaluated for Ra and KHN. The pH values of the storage media were measured weekly. Data were tested for significant differences by repeated-measures three-way analysis of variance and Tukey tests (p<0.05). Composites were found to present lower roughness values and higher hardness values than the ionomeric materials under all storage conditions. After degradation, the KHN of all experimental samples decreased significantly, while the Ra of the ionomeric materials increased, depending on the media, with a markedly negative impact of Coca-Cola and orange juice. There was no difference among the storage media for Filtek Z350 with regard to the KHN values. Nanofillers did not show any influence on the roughness and hardness of resin-modified glass ionomer cements and resin composites concerning their degradation resistance.

Management of a Perforating External Infection Related Resorptive Defect: A Case Report

This case report describes the treatment of an external infection related root resorption in a maxillary left central incisor which perforated the root canal apical to the cervical area. Since the resorptive perforation was large with concomitant bony lesion, treatment with a combination of nonsurgical and surgical approach was chosen. After a surgical flap was reflected, the pathologic defect was curetted, root canal space was dried and the resorptive defect was repaired with light-cured glass ionomer cement. At the same visit, root canal filled with gutta percha by lateral condensation technique and the bony cavity was filled with calcium hydroxyappatite crystal. After 18 months, the patient remained asymptomatic and the tooth was functional. DOI: http://dx.doi.org/10.3329/medtoday.v24i1.14117 Medicine TODAY Vol.24(1) 2012 pp.48-51

SEALING ABILITY OF MINERAL TRIOXIDE AGGREGATE, CALCIUM PHOSPHATE CEMENT, AND GLASS IONOMER CEMENT IN THE REPAIR OF FURCATION PERFORATIONS

The purpose of this study was to evaluate the in vitro sealing ability of three repair materials. Mineral trioxide aggregate (MTA; Group A), calcium phosphate cement (CPC; Group B), and light cured glass ionomer cement (GIC; Group C) when used to repair the perforation created in the pulpal floor of fifty extracted human permanent molars. Preparation of access openings and furcation perforations were done, and the teeth divided into five experimental groups (A, B, C) including two controls (D, E) with ten samples in each group randomly. Following the repair procedure, the pulp chambers and access openings were filled with composite resin and immersed in 2% methylene blue solution for 48 hours. The teeth were sectioned longitudinally and the linear dye penetration measured under a stereomicroscope. The comparison of the linear length of micro-leakage (mm) among the experimental groups revealed no significant difference (p = 0.332). On calculating the percentage of depth of leakage to the total length of the perforation, it was observed that the mean leakage was 35.5% in Group A, 53.6% in Group B and the highest, 87.5% in Group C. The mean of leakage percentage was statistically significant by Kruskal-Wallis test (p = 0.003). The results indicated that the dye penetration used as furcation perforation repair material was least with mineral trioxide aggregate. Comparing the depth of penetration of dye, 50% of the Group A samples showed less than 25% of depth penetration. While 40% of Group B cases had more than 50% dye penetration. In our study, all Group C teeth had > or = 50% dye penetration. The present study indicated that GIC had the greatest dye penetration followed by CPC and MTA. Mineral trioxide aggregate and calcium phosphate cement had comparatively better sealing ability than glass ionomer cement.

Comparative evaluation of microleakage of various retrograde filling materials: An in vitro study.

Objective:The present study is envisaged to evaluate and compare the microleakage of mineral trioxide aggregate (MTA) with commonly used retrograde filling materials, like light-cured composite with dentin-bonding agents, light-cured glass ionomer cement (LC GIC) and resin-modified zinc oxide eugenol.Materials and Methods:Ninety freshly extracted non-carious single-rooted human anterior teeth were used in the study. They were randomly divided into four experimental groups and two control groups of 15 each. Following the biomechanical preparation, all teeth were obturated and then the apices of the obturated teeth were resected by removing 3 mm of each apex at 90° to the long axis of the tooth with a straight fissure bur in a high-speed air-rotor handpiece with water coolant. A 3-mm-deep root end cavity was prepared and the root end fillings were placed as per the manufacturer's instructions and according to the groups divided. The samples were then immersed in 1% methylene blue at room temperature for 72 h, 96 h and 1 week and the dye penetration was measured.Results and Conclusion:All the four materials used in the study showed some microleakage throughout the experimental period. The sealing ability in terms of microleakage can be summarized as: MTA > Composite resin with dentin bonding agent > LC GIC > Resin modified zinc oxide eugenol.

Evaluation of internal adaptation of dental adhesive restorations using micro-CT

Objectives: The internal adaptation of composite restorations with or without resin modified glass ionomer cement (RMGIC) was analyzed non-destructively using Microcomputed tomography (micro-CT). Materials and Methods: Thirty intact human teeth were used. The specimens were divided into 3 groups. In the control group, the cavities were etched with 10% phosphoric acid for 15 sec. Composite resin was filled into the cavity without adhesive. In group 1, light cured glass ionomer cement (GIC, Fuji II LC, GC) was applied as a base. The cavities were then etched, bonded, light cured and filled with composites. In group 2, the cavities were then etched, bonded, light cured and filled with composites without base application. They were immersed in a 25% silver nitrate solution. Micro-CT was performed before and after mechanical loading. One-way ANOVA with Duncan analysis was used to compare the internal adaptation between the groups before or after loading. A paired t-test was used to compare internal adaptation before and after mechanical loading. All statistical inferences were made within the 95% confidence interval. Results: The silver nitrate solution successfully penetrated into the dentinal tubules from the pulp spaces, and infiltrated into the gap between restoration and pulpal floor. Group 2 showed a lower adaptation than the control group and group 1 (p

Comparative study of microleakage of three different flowable restorative materials and light-cure glass ionomer cement in class V cavities: An in-vitro study

In vitro study was done to compare the sealing ability of 3 Flowable restorative materials (Flowable composite, Flowable compomer, Flowable ownocer) and a Light cure Glass-ionomer cement in class V cavities at occlusal and gingival margin after 24 hrs of dye immersion. Standardized class V cavities were prepared on the buccal aspect of forty extracted premolars. These 40 teeth were divided into 4 main groups. Group A (Flowable ormocer), Group B (Flowable compomer), Group C (Flowable composite) and Group D (Light cure Glass-ionomer cernent). The samples were then sectioned bucco-lingually through the centre of restoration and examined under stereomicroscope for dye penetration. Flowable ormocer showed least microleakage of all the material at occlusal and gingival margin after 24 hrs of dye immersion. Light cure Glass-ionomer cement showed the maximum microleakage and least sealing ability of all the materials. Flowable ormocer with best sealing ability can be advocated for class V situations.

Effect of internal matrices of hydroxyapatite and calcium sulfate on the sealing ability of mineral trioxide aggregate and light cured glass ionomer cement

Objective:The present study was undertaken to evaluate the effect of hydroxyapatite (HA) and calcium sulfate (CS) on the sealing ability of mineral trioxide aggregate (MTA) and light cured glass ionomer cement (LC GIC) when used to repair furcation perforations.Materials and Methods:The study was conducted on 70 human molars. Sixty teeth with furcal perforations were randomly divided into six groups of 10 teeth each and repaired with MTA or LC GIC either alone or over an internal matrix, i.e., CS or HA. Access openings were filled with composite resin. Five teeth with unrepaired perforations were used as positive controls and five teeth without perforations were used as negative controls. The teeth were immersed in a solution of 2% methylene blue dye for 2 weeks. The samples were then sectioned and evaluated for linear dye leakage and analyzed statistically.Results:MTA showed the best sealing ability followed by LC GIC, MTA + CS, MTA + HA, LC GIC + CS and LC GIC + HA.Conclusion:Neither of the two internal matrices improved the sealing ability of the repair materials used.

A comparative histological analysis of human pulp following direct pulp capping with Propolis, mineral trioxide aggregate and Dycal

Permanent teeth pulp exposures have traditionally been treated with calcium hydroxide pulp capping. The aim of this study was to investigate the response of human pulp tissue which were mechanically exposed to a new material, Propolis and compare it with two existing and commonly used pulp capping agents (mineral trioxide aggregate and Dycal). Thirty-six intact human premolars were mechanically exposed. Teeth were divided into six groups of 6 teeth each and were capped with Propolis, mineral trioxide aggregate and Dycal. Final restoration was done with posterior composite resin using light cured glass ionomer cement as a liner. The teeth were then extracted on the 15th or the 45th day and processed for histological evaluation. Differences in inflammatory response and dentine bridge formation of the exposed pulp to the three different materials were statistically calculated using chi-square test and were found to be non-significant. There was more pulp inflammation in teeth treated with Dycal than with Propolis and MTA on the 15th as well as on the 45th day. Propolis and MTA showed bridge formation in more teeth, and the bridges were in closer proximity to pulp capping material than teeth treated with Dycal on the 45th day. The response of pulps to Propolis as a pulp capping agent was comparable to MTA and Dycal.

Characterization of a novel light‐cured star‐shape poly(acrylic acid)‐composed glass‐ionomer cement: fluoride release, water sorption, shrinkage, and hygroscopic expansion

This study evaluated the fluoride release, water sorption, curing shrinkage, and hygroscopic expansion of a novel experimental light-cured glass-ionomer cement. The effects of glycidyl methacrylate (GM) grafting, polymer : water (P : W) and powder : liquid (P : L) ratios were investigated. Commercial Fuji II and Fuji II LC cements were used as controls for comparison. All the specimens were conditioned in deionized water at 37 degrees C before testing. The results demonstrated that the experimental cement showed lower burst and slower bulk fluoride release than Fuji II and Fuji II LC. The experimental cement absorbed more water than Fuji II and Fuji II LC as a result of its hydroxyl and carboxyl functional group content. The lower water-diffusion rate and reduced hygroscopic expansion of the experimental cement suggest that it had a highly crosslinked network. Both Fuji II and Fuji II LC exhibited much higher shrinkage values (2.8% and 4.7%) than the experimental cement (0.8%). It appears that this novel cement will be a clinically attractive dental restorative because not only has it shown superior mechanical strength, it has also demonstrated satisfactory physical properties.