Long-Term Assessment of Contemporary Ion-Releasing Restorative Dental Materials

The objective was to evaluate new commercially available ion-releasing restorative materials and compare them to established anti-cariogenic materials. Four materials were tested: alkasite Cention (Ivoclar Vivadent) in self-cure or light-cure mode, giomer Beautifil II (Shofu), conventional glass-ionomer Fuji IX (GC), and resin composite Tetric EvoCeram (Ivoclar Vivadent) as a control. Flexural strength, flexural modulus, and Weibull modulus were measured one day, three months, and after three months with accelerated aging in ethanol. Water sorption and solubility were evaluated for up to one year. Degree of conversion was measured during 120 min for self-cured and light-cured Cention. In this study, Beautifil II was the ion-releasing material with the highest flexural strength and modulus and with the best resistance to aging. Alkasite Cention showed superior mechanical properties to Fuji IX. Weibull analysis showed that the glass-ionomer had the least reliable distribution of mechanical properties with the highest water sorption. The solubility of self-cured alkasite exceeded the permissible values according to ISO 4049. Degree of conversion of light-cured Cention was higher than in self-cure mode. The use of alkasite Cention is recommended only in the light-cure mode.

Giomer composite compared to glass ionomer in occlusoproximal ART restorations of primary molars: 24-month RCT

BACKGROUND

Occlusoproximal restorations of primary molars usually fail, so it is necessary to investigate new materials that may overcome this challenge. Thus, this trial aimed to evaluate the longevity of occlusoproximal ART restorations in primary molars using a glass ionomer cement - GIC (Equia Forte^® - GC Corp) and a Giomer resin composite - GCR (Beautifil Bulk Restorative^® - Shofu Inc) after 24 months.

METHODS

One hundred and eighty-two (182) children aged from 4 to 8 years were selected and randomly assigned to GIC or GCR. A paediatric dentist treated them in the school setting in Cerquilho, Brazil, and the restorations were assessed after 3, 6, 12, 18 and 24 months. The primary outcome was the restoration survival, evaluated using the Kaplan-Meier and superiority Cox regression analyses. Intention to treat (ITT) was performed as a sensitivity analysis using superiority test P value and confidence interval (CI = 95%). Independent variables included gender, age, molar, jaw, cavity volume and caries experience.

RESULTS

The restoration survival after 24 months was GIC = 58.1% and GCR = 49.1% (HR = 1.24; CI = 0.97-1.59). ITT analysis showed a success of GIC = 61.1% and GCR = 52.2% (RR = 1.17; CI = 0.91-1.52). The superiority hypothesis was not proved in both analyses (P > 0.05).

CONCLUSION

GCR does not have superior longevity than GIC in occlusoproximal ART restorations of primary molars.

Experimental Bioactive Glass-Containing Composites and Commercial Restorative Materials: Anti-Demineralizing Protection of Dentin

The purpose of this in vitro study was to investigate whether different types of experimental and commercial restorative dental materials can protect dentin against acid-induced softening. Experimental composites were prepared with a photocurable mixture of methacrylates and two types of bioactive glass (45S5 and a customized low-Na F-containing formulation). Human dentin samples were prepared from mid-coronal tooth slices and immersed in lactic acid solution (pH = 4.0) at 5 mm from set specimens of restorative material. After 4, 8, 12, 16, 20, 24, 28, and 32 days, surface microhardness of dentin samples and pH of the immersion solution were measured, followed by replenishing of the immersion medium. Microstructural analysis was performed using scanning electron microscopy. The protective effect of restorative materials was determined as dentin microhardness remaining statistically similar to initial values for a certain number of acid additions. Scanning electron microscopy showed a gradual widening of dentinal tubules and proved less discriminatory than microhardness measurements. To produce a protective effect on dentin, 20 wt% of low-Na F-containing bioactive glass was needed, whereas 10 wt% of bioactive glass 45S5 was sufficient to protect dentin against acid-induced demineralization. The anti-demineralizing protective effect of experimental and commercial restoratives on dentin was of shorter duration than measured for enamel in a previous study using the same experimental approach.

A comparative evaluation of the fracture resistance of endodontically treated teeth with simulated invasive cervical resorption cavities restored with different adhesive restorative materials: An in vitro study

Aim:

The aim of the study was to compare the fracture resistance of endodontically treated teeth with simulated invasive cervical resorption cavities, restored with different restorative materials, namely, conventional glass-ionomer cement (CGIC), resin-modified glass-ionomer cement (RMGIC), flowable composite (FC), and giomer.

Methods:

Sixty extracted human permanent maxillary central incisor teeth were assigned to six groups,which were, Group 1 (intact teeth, control), Group 2 (teeth with biomechanical preparation and resorption cavity), Group 3 (CGIC), Group 4 (RMGIC), Group 5 (FC), and Group 6 (giomer). Except for Group 1, other groups were subjected to endodontic treatment. Teeth of Group 2 were left unobturated and teeth of Groups 3–6 were obturated. A simulated resorption cavity was prepared labially in the specimens belonging to Groups 2–6 and restored with respective restorative materials. The specimens were subjected to compressive load until failure in an Instron testing machine and the load at failure was recorded in Newtons.

Statistical Analysis:

The data obtained were statistically analyzed using one-way ANOVA, pair-wise comparison was made with Tukey's multiple comparison test, and P < 0.05 was considered statistically significant.

Results:

There was a statistically significant difference in the fracture resistance of intact teeth and endodontically treated teeth with simulated invasive cervical resorption cavities restored with different adhesive restorative materials. Among the restored teeth, there was no significant difference.

Conclusion:

Intact teeth were found to have the highest resistance to fracture followed by those restored with giomer, FC, RMGIC, and CGIC in that order.

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

OBJECTIVE

This study evaluated the microtensile bond strength (μTBS) of ion-releasing restorative materials to sound and caries-affected dentin (CAD).

STUDY DESIGN

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.

RESULTS

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.

CONCLUSION

The use of the giomer can be recommended due to its more stable bond durability.

Fluoride release and fluoride-recharging ability of three different sealants

BACKGROUND

We aimed to determine the fluoride release and fluoride-recharging ability of a sealant containing surface pre-reacted glass (S-PRG) ionomer filler particles (BeautiSealant) with a fluoride-releasing resin sealant (Helioseal F), and a glass-ionomer sealant (Fuji VII).

METHODOLOGY

Forty-eight disc-shaped specimens of each material were immersed in deionized water to determine the fluoride release utilizing a fluoride ion-selective electrode. After 21 days, 8 specimens were soaked in 0.22% Sodium Fluoride solution for 2 min; 8 specimens were coated with 1.23% Acidulated Phosphate Fluoride (APF) gel for 4 min, and the fluoride-recharging ability was evaluated for 40 days. Data were analyzed using one way-ANOVA and Bonferroni post hoc tests.

RESULTS

Total fluoride release over the 21-day period was: Fuji VII > BeautiSealant > Helioseal F, (P = 0.000). After refluoridation of the specimens with 0.22% Sodium Fluoride solution, the cumulative fluoride release during the 40-day period for each material was: BeautiSealant > Fuji VII > Helioseal (P = 0.000). After exposure to 1.23% APF gel, the cumulative fluoride release during the 40-day period for each material was: BeautiSealant > Fuji VII > Helioseal F (P = 0.000).

CONCLUSION

Glass ionomer-based sealants (Fuji VII) exhibited higher initial fluoride release whilst the surface pre-reacted glass-ionomer filler containing sealant (BeautiSealant) demonstrated superior fluoride recharging properties.

Commercially Available Fluoride-Releasing Restorative Materials: A Review and a Proposal for Classification

Resin composite and glass ionomer cement (GIC) are the most commonly used dental materials to perform direct restorations. Both have specific characteristics that explain their popularity and their limits. More than 20 years ago, the first attempt (followed by others) to combine the advantages of these two families was performed with compomers, but it was not very successful. Recently, new formulations (also called 'smart materials') with claimed ion release properties have been proposed under different family names, but there are few studies on them and explanations of their chemistries. This comprehensive review aims to gather the compositions; the setting reactions; the mechanical, self-adhesive, and potential bulk-fill properties; and the ion release abilities of the large existing families of fluoride-releasing restorative materials and the new restorative materials to precisely describe their characteristics, their eventual bioactivities, and classify them for an improved understanding of these materials. Based on this work, the whole GIC family, including resin-modified and highly viscous formulations, was found to be bioactive. Cention N (Ivoclar Vivadent, AG, Schaan, Lietschentein) is the first commercially available bioactive resin composite.

A comparative in vitro study on fluoride release and water sorption of different flowable esthetic restorative materials

OBJECTIVES

The objective of the study was to evaluate fluoride release and water sorption of three flowable esthetic restorative materials: a giomer, a fluoride-releasing resin composite, and a nonfluoridated resin composite.

MATERIALS AND METHODS

Ten samples from a giomer, a fluoride releasing nano-hybrid, and a nonfluoridated nano-hybrid composite were prepared and immersed in deionized water. Fluoride measurements were done using an ion-specific electrode attached to a microprocessor-based fluoride meter after 1 day, 1 week, and 4 weeks. Another thirty samples were made and placed in desiccators. Water sorption was calculated by weighing the specimens before and after water immersion for 1 day, 1 week, and 4 weeks. Data analysis was done using two-way ANOVA, paired t-test (P < 0.05), and Pearson's correlation coefficient to calculate correlations between fluoride release and water sorption.

RESULTS

The highest fluoride release was from giomer after 1 day, it was statistically significant from all other groups. Both nano-hybrid composites after 1 day showed significantly lower water sorption which was different than all the other groups. Pearson's correlation showed no significant correlations between fluoride release and water sorption.

CONCLUSIONS

Fluoride release is material and time dependent, while water sorption is material dependent.

Giomers in dentistry - at the boundary between dental composites and glass-ionomers

Introduction

From the variety of direct restorative dental materials, composite resins are considered as having the most esthetic and functional properties. The conservative preparation, esthetic results, good mechanical qualities and surface finishing properties of dental composites, combined with the protective properties of fluoride from glass-ionomers, led to a new generation of dental materials: the giomers.

Objective

The purpose is to review the available literature about the giomers, regarding the chemical composition, handling properties and esthetics, adhesion and microleakage, fluoride releasing and protection offered, clinical indications.

Method

The search was carried out using ScienceDirect and PubMed databases with the following keywords: giomer, esthetic properties giomers and fluoride releasing giomers. A total of 232 articles were initially selected, with the following inclusion criteria: full text articles, written in English, with topics on the properties and the clinical implications of giomers. Papers presented as abstract were not included. In the next step, review articles, duplicates, and articles in other languages were removed; as a result, a total of 44 sources published between 2004 and 2017 were selected.

Results

The selected articles referred to the following aspects about the giomers: chemical composition (8 articles), adhesion and microleakage (10 articles), fluoride releasing and pulp protection (15 articles), clinical indications (6 articles), effects of additional treatments and dietary habits (11 articles).

Clinical and Radiographic Success of Three Adhesive Restorative Materials in Primary Molar Proximal Lesions: A Randomized Clinical Trial

AIM

The aim of this study was to evaluate and compare the clinical and radiographic success of primary molar proximal lesions in 4-8 years children restored with three adhesive restorative materials followed up for 12 months.

MATERIALS AND METHODS

This study was carried out on 102 primary molars of 51 children in the age range of 4-8 years. In all the participants, Class II lesions were restored and randomly allocated into three material groups as giomer group, nano-ionomer group, and light-cured glass-ionomer cement (LC-GIC) group based on the restorative material used. All the restorations were evaluated and scored according to federation dentaire internationale (FDI) criteria for clinical and radiographic success rate at 3, 6, and 12 months' interval. Data were formulated in a predesigned format and were subjected to statistical analysis using the Chi-square test and Fisher's exact test.

RESULTS

There was no statistically significant difference observed among the restorative material groups to all the properties of FDI criteria. The overall success rates of restorative materials at 3, 6, and 12 months' interval were as follows: giomer - 100%, 100%, and 94.1%; nano-ionomer - 97%, 94%, and 85.3%; and LC-GIC - 100%, 94%, and 88.2%.

CONCLUSION

The highest clinical success rate was found for the giomer group followed by LC-GIC group and the least for the nano-ionomer group, whereas the highest radiographic success rate was found for giomer as well as LC-GIC group and the least for nano-ionomer group.

Fracture resistance of posterior teeth restored with high-viscosity bulk-fill resin composites in comparison to the incremental placement technique

Aim:

Comparative evaluation of the fracture resistance of maxillary premolar teeth restored with two high-viscosity bulk-fill composites and incrementally placed composite.

Materials and Methods:

Seventy-five freshly extracted maxillary premolar teeth were selected. Fifteen specimens served as positive control (Group 1). Mesio-occluso-distal cavity preparation was prepared on the rest of the specimens. These specimens were further divided into four groups: unrestored teeth (Group 2), teeth restored with incrementally placed nanocomposite (Group 3), teeth restored with high-viscosity bulk-fill giomer (Group 4), and teeth restored with high-viscosity bulk-fill nanocomposite (Group 5). The specimens were then subjected to compressive axial load using Instron universal testing machine. Data were analyzed using data were analyzed using Statistical package for social sciences software (SPSS v 20.0, IBM Corp.).

Results:

The positive control group exhibited highest fracture resistance (1104.70 ± 122.2 N). There was no statistically significant difference seen in between the incrementally placed nanocomposite and high-viscosity nanocomposite (P > 0.05). The fracture resistance values displayed by the high-viscosity bulk-fill giomer were found to be statistically lower than the other two groups.

Conclusion:

High-viscosity bulk-fill nanocomposite may substitute incrementally placed nanocomposite with respect to fracture resistance.

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

PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Comparative evaluation of fluoride release and recharge potential of novel and traditional fluoride-releasing restorative materials: An in vitro study

Aim

The aim of this study was to evaluate and compare the fluoride ion release and uptake of glass ionomer cement GP IX Extra (GE), EQUIA^® Forte Fil (EF), Beautifil Bulk (BB), Dyract^® XP (DXP), Tetric N-Ceram^® (TNC) in vitro.

Materials and Methods

The restorative materials were divided into five groups (n = 12), namely G1 - GE, G2 - EF, G3 - BB, G4 - DXP, G5 - TNC. Fluoride release was checked using fluoride ion-selective electrode (Orion 9609BNWP, Ionplus Sure-Flow Fluoride, Thermo Scientific, USA) at time intervals of 1 day and thereafter at 3, 7, 14, 21, and 28 days. Following this, fluoride recharge was done with 1.23% acidulated phosphate fluoride gel (12,300 ppm, Pascal International Inc., 2929 Northup Way, Bellevue, USA) after 28 days and each sample was re-checked for fluoride release at the same time intervals.

Statistical Analysis

One-way ANOVA with post hoc Games-Howell test for intergroup and repeated measures ANOVA with post hoc Bonferroni test for intragroup analysis. P < 0.05 was considered statistically significant.

Results

On intergroup analysis, Group 2 showed high values of fluoride release and recharge at all-time intervals which were significantly higher (P < 0.001) than Groups 1, 3, 4 and 5. Intragroup analysis showed significantly higher (P < 0.001) fluoride release and recharge at the end of day 1 which decreased progressively with time for all the tested materials.

Conclusion

EF showed the highest fluoride release and recharge potential across all time intervals compared to other tested restorative materials and the greatest fluoride release was seen on day 1.

Effects of thermal fatigue on shear punch strength of tooth-colored restoratives

Aims:

This study investigated the effect of thermal fatigue on the shear strength of a range of tooth-colored restorative materials including giomers, zirconia-reinforced glass ionomer cement (GIC), nano-particle resin-modified GIC, highly viscous GICs, and composite resin.

Materials and Methods:

Twenty specimens of each material were fabricated in standardized washers (17 mm outer diameter, 9 mm internal diameter, 1 mm thick). The specimens were cured, stored in 100% humidity at 37.5°C for 24 h, and randomly divided into two groups of 10. Group A specimens were nonthermocycled (NT) and stored in distilled water at 37°C for 168 h. Group B specimens were thermocycled (TC) for 10,000 cycles (168 h) with baths X, Y, and Z adjusted to 35°C, 15°C, and 45°C, respectively. Each cycle had dwell times of 28 s in X, and 2s in Y/Z in the order XYXZ. Specimens then underwent shear punch testing at a crosshead speed of 0.5 mm/min with a 2 kN load cell. Statistical analysis of shear strength was done using t-test and two-way ANOVA/Scheffe's post hoc test at significance level P < 0.05.

Results:

The effect of thermal fatigue on shear strength was material dependent. Except for the “sculptable” giomer (Beautifil II) and a highly viscous GIC (Fuji IX GP Fast), no significant differences in shear strength were generally observed between the NT and TC groups. For both groups, the composite resin (Filtek Z250XT) had the highest shear strength while the zirconia-reinforced (zirconomer) and a highly viscous GIC (Ketac Molar Quick) had the lowest.

Conclusions:

The effect of thermocycling on shear strength was material dependent. Thermal fatigue, however, did not significantly influence the shear strength of most materials assessed. The “sculptable” composite and giomer were significantly stronger than the other materials evaluated. Shear strength of the “flowable” injectable hybrid giomer was intermediate between the composite and GICs.

Comparative study of fluoride released and recharged from conventional pit and fissure sealants versus surface prereacted glass ionomer technology

Context:

The fluoride release of sealants in vitro shows a marked decrease. Giomers are distinguishable from manufactured resin-based sealants and contain prereacted glass-ionomer particles (PRG).

Aims:

To compare the amounts of fluoride released from the main pit and fissure of a resin-based sealant with that from a Giomer and to assess the abilities of the sealant and the Giomer to recharge when exposed to regular use of fluoride rinse.

Materials and Methods:

The readings for the fluoride concentration were carried out for 60 days using a fluoride ion-specific electrode. After this period, the samples were recharged using a fluoride mouth rinse. The amount of fluoride released after this recharge was determined for 5 days. The data were analyzed using Student's t- and analysis of variance tests.

Results:

In general, all materials presented higher fluoride release in the first 24 h; G1 and G4 showed a higher fluoride release in this period. On the other hand, G3 and G1 presented the most constant fluoride release until the 8^th day, wherein all the sealants considerably decreased in the amount of fluoride released.

Conclusion:

G1 and G3 released higher concentrations of fluoride, although no significant differences were found. Giomers recharged in the first 24 h after polymerization presented an improved and sustained fluoride release.

The effect of different beverages on surface hardness of nanohybrid resin composite and giomer

Aims:

To investigate the effects of five beverages (apple cider, orange juice, Coca-Cola, coffee, and beer) on microhardness and surface characteristic changes of nanohybrid resin composite and giomer.

Materials and Methods:

Ninety-three specimens of each resin composite and giomer were prepared. Before immersion, baseline data of Vicker's microhardness was recorded and surface characteristics were examined using scanning electron microscopy (SEM). Five groups of discs (n = 18) were alternately immersed in 25 mL of each beverage for 5 s and in 25 mL of artificial saliva for 5 s for 10 cycles. Specimens were then stored in artificial saliva for 24 h. This process was repeated for 28 days. After immersion, specimens were evaluated and data were analyzed by two-way repeated analysis of variance (ANOVA), Tukey's honestly significant difference (HSD), and a t-test (α = 0.05).

Results:

Microhardness of all groups significantly decreased after being immersed in the tested beverages (P < 0.05). SEM photomicrographs presented surface degradation of all groups.

Conclusions:

The effect of these beverages on the surface of both restorative materials also depended upon the exposure time and chemical composition of the restorative materials and beverages.

Effects of surface treatments of conventional glass-ionomer on shear bond strength to giomer

BACKGROUND

An appropriate bond between glass-ionomer and the superficial resin materials is very important for the success of sandwich technique. The aim of the present in vitro study was to evaluate the effect of three surface treatments of conventional glass-ionomer on its shear bond strength to giomer.

MATERIALS AND METHODS

Sixty cylindrical specimens of a conventional glass-ionomer (GC Fuji II) were prepared and randomly divided into three groups (n = 20). The specimens in groups 1 and 2 were treated with total-etch adhesive resin (Single Bond) along with acid etching, and self-etch adhesive resin (FL-Bond II) on the set glass-ionomer, respectively. Specimens in group 3 were treated with self-etch adhesive resin (FL-Bond II) before initial setting of the glass-ionomer was complete. Then a giomer restorative (Beautifil II) was added to the specimens. Subsequent to thermocycling, the specimens were subjected to shear bond strength test. Failure modes were evaluated under a stereomicroscope. Data were analyzed by one-way analysis of variance and a post hoc Tukey test at a significance level of P < 0.05.

RESULTS

There were statistically significant differences in bond strengths between the groups (P < 0.0005). Differences in bond strengths between group 2 and other groups were significant (P < 0.0005) while the differences between groups 1 and 3 were not significant. Failures were predominantly of the cohesive type in all the groups.

CONCLUSION

Based on the results of this study, the use of self-etch adhesive resin (FL-Bond II) on the set glass-ionomer yielded the highest bond strength in the glass-ionomer/giomer sandwich technique.