Hypermineralization of dentinal lesions adjacent to glass-ionomer cement restorations

Influence of the curing mode on fluoride ion release of self-adhesive resin luting cements in water or during pH-cycling regimen

This study evaluated the effects of curing modes and storage conditions on fluoride release of resin cements. In phase 1, the cumulative fluoride release rate from samples of the resin cements (Panavia F 2.0, RelyX Unicem, MaxCem, and BisCem) was quantified after 15 days storage in water (n=4). In phase 2, the fluoride release profiles from the same materials were analyzed during pH cycling (n=4). In this second phase, fluoride was measured at specific times (one, two, three, five, eight, and 15 days). Disk-shaped specimens were prepared (10 mm × 0.5 mm), and the materials were either light activated or allowed to autopolymerize. For both phases, the fluoride release was measured using a fluoride ion-specific electrode. The fluoride release in water was not affected by the curing mode of RelyX Unicem and Maxcem resin cements. Panavia F. 2.0 and BisCem resin cements, either light cured or autopolymerized modes, released higher amounts of fluoride in water than the other self-adhesive cements. In phase 2, the concentration of fluoride released decreased from the first day of pH cycling until the 15th day for all resin cements, for both curing modes, regardless of the storage solution used (demineralizing/remineralizing). The fluoride release rate during pH cycling by Panavia F 2.0 and MaxCem was not affected by the curing mode. The effect of the curing mode on fluoride ion release in water or during pH cycling was product dependent.

Therapeutic effect of glass-ionomers: an overview of evidence

The requirements for an ideal restorative material include adhesion to tooth structure (enamel and dentine) and an ability to withstand the traumas of occlusion. However, some level of an anticaries effect is also desirable. After a long history of glass-ionomer cement (GIC) development, an evidence base in support of the therapeutic effect of GIC, particularly with regard to its anticaries effect, is emerging. This evidence is increasingly presented through systematic reviews of clinical GIC application and, to a certain extent, relates to a caries-preventive effect of the material itself. However, the strength of evidence supporting other aspects of GIC, such as a higher remineralizing effect, fluoride uptake in hard tooth tissue and fluoride release of GIC, is limited. Nevertheless, the results of these in situ and laboratory trials provide valuable insights into factors that facilitate understanding of the clinical efficacy of GIC.

Absence of carious lesions at margins of glass-ionomer cement and amalgam restorations: An update of systematic review evidence

Background

This article aims to update the existing systematic review evidence elicited by Mickenautsch et al. up to 18 January 2008 (published in the European Journal of Paediatric Dentistry in 2009) and addressing the review question of whether, in the same dentition and same cavity class, glass-ionomer cement (GIC) restored cavities show less recurrent carious lesions on cavity margins than cavities restored with amalgam.

Methods

The systematic literature search was extended beyond the original search date and a further hand-search and reference check was done. The quality of accepted trials was assessed, using updated quality criteria, and the risk of bias was investigated in more depth than previously reported. In addition, the focus of quantitative synthesis was shifted to single datasets extracted from the accepted trials.

Results

The database search (up to 10 August 2010) identified 1 new trial, in addition to the 9 included in the original systematic review, and 11 further trials were included after a hand-search and reference check. Of these 21 trials, 11 were excluded and 10 were accepted for data extraction and quality assessment. Thirteen dichotomous datasets of primary outcomes and 4 datasets with secondary outcomes were extracted. Meta-analysis and cumulative meta-analysis were used in combining clinically homogenous datasets. The overall results of the computed datasets suggest that GIC has a higher caries-preventive effect than amalgam for restorations in permanent teeth. No difference was found for restorations in the primary dentition.

Conclusion

This outcome is in agreement with the conclusions of the original systematic review. Although the findings of the trials identified in this update may be considered to be less affected by attrition- and publication bias, their risk of selection- and detection/performance bias is high. Thus, verification of the currently available results requires further high-quality randomised control trials.

Micromechanical and Structural Analysis of Compromised Dental Tissues

With the continual development of new dental materials and treatment techniques, dental materials research is now more important than ever. Although the traditional method of materials and treatment technique assessment was laboratory based, there is a need for investigations into the clinical outcomes of in-vitro research. The aim of this paper is to discuss the micromechanical and structural analysis of compromised dental tissues that affect young children, using a biomaterial and clinical approach.

Caries-removal effectiveness and minimal-invasiveness potential of caries-excavation techniques: a micro-CT investigation

OBJECTIVES

To determine the caries-removal effectiveness (CRE) and minimal-invasiveness potential (MIP) of contemporary caries-removal techniques.

METHODS

Carious molars were scanned using micro-CT, after which dentine caries was removed by 9 contemporary caries-removal techniques. The micro-CT was repeated and CRE was determined on basis of the relative volume of residual caries and the mineral density (MD) at the cavity floor. MIP was determined by measuring the cavity size relative to the initial size of the caries lesion.

RESULTS

CRE and MIP varied most for the Er:YAG laser (Kavo) despite its laser-induced fluorescence (LIF) feedback system. Whilst some specimens revealed much residual caries, others showed over-excavation into sound dentine. With the highest Relative Cavity Size, the Er:YAG laser presented the lowest MIP. Rotary/oscillating instruments revealed a more favourable CRE with some tendency towards over-excavation, except for CeraBur (Komet-Brasseler) and Cariex (Kavo) that typically left caries at the cavity floor and cavity walls, respectively. Chemo-mechanical excavation aided by conventional metal excavators (Carisolv, MediTeam; exp. SFC-V and SFC-VIII, 3M-ESPE) combined best CRE with MIP. When however a plastic excavator was used along with exp. SFC-VIII, caries was less completely removed.

SIGNIFICANCE

Er:YAG-laser aided by LIF resulted in non-selective caries removal. Rotary/oscillating caries removal may lead to over-excavation, especially when burs are combined with Caries Detector (Kuraray). This risk for over-excavation is reduced when a tungsten-carbide bur is solely used. On the contrary, Cariex (Kavo) and CeraBur showed a tendency for under-preparation. Chemo-mechanical methods were most selective in removing caries, whilst preserving sound tissue.

Glass-ionomer cements as restorative and preventive materials

This article focuses on glass-ionomer cement (GIC) and its role in the clinical management of caries. It begins with a brief description of GIC, the mechanism of fluoride release and ion exchange, the interaction between GIC and the external environment, and finally the ion exchange between GIC and the tooth at the internal interface. The importance of GIC, as a tool, in caries management, in minimal intervention dentistry (MI), and Caries Management by Risk Assessment (CAMBRA) also will be highlighted.

Effect of monomer composition on crystal growth by resin containing bioglass

This study evaluated the effect of resin monomer composition on crystal growth at the interface between the resin/bioglass composites and water. Light-cured resin that contained 2-bis[4(2-hydroxy-3-methacryloyloxy-propyloxy)-phenyl], 2-hydroxyethyl methacrylate, and triethylene glycol dimethacrylate with different compositions were used. Resin/bioglass composites were prepared with 40 mass% bioglass and 60 mass% resin. The resin/bioglass composites were stored in deionized distilled water for 24 h (control group) or 3-12 months (experimental groups). After water storage, the disk surfaces were examined by light- and scanning electron microscopy. Chemical states of the crystals were analyzed by laser-Raman spectroscopy and micro-X-ray diffractometry. The microscopic analysis showed crystal on the resin disks surface after six months of water storage for hydrophilic resins. However, there was no crystal formation in the control and the experimental groups of specimens of hydrophobic resins. Raman analysis showed the chemical states of the crystals formed on the resin matrix and bioglass to be different. The micro-X-ray analysis of crystals on resin disks identified them to be calcium carbonate. This crystal formation occurred in water instead of simulated body fluid. In conclusion, the resin monomer compositions affected the ability to induce crystal growth on the surfaces of disks containing bioglass.

A review--micromorphological evidence of degradation in resin-dentin bonds and potential preventional solutions

Resin adhesion to dentin was first achieved in 1982 through mechanical hybridization between resin and collagen fibrils using an adhesive resin containing a functional monomer. Over the last 2 decades, newly developed adhesive resins have attempted to improve the bond strength at least in the first 24 h after bonding. Although much is known about the initial bond strength, learned through morphological analysis, the long-term durability of bonds has not yet been established analytically. However, numerous recent studies have shown chemical biodegradation of resin-dentin bonds under various testing regimes. In general, studies have shown that dentin bond strength decreases over time due to degradation of the resin and the collagen fibrils within the bonds. Furthermore, crystal formation around cured bonding resins has been reported in a number of adhesives after long-term water storage. However, the extent and process of degradation or crystallization is adhesive type specific. This review mainly summarizes the most recent and state of the art work in degradation of the bonding of dental restorative compounds with dentin based on micromorphological data of scanning and transmission electron microscopy.

Effect of a new desensitizing material on human dentin permeability

OBJECTIVES

Resin-modified glass ionomers (RMGI) have demonstrated clinical success providing immediate and long-term relief from root sensitivity. RMGIs have been recently introduced as paste-liquid systems for convenience of clinical usage. The objective of this study was to measure the ability of a new paste-liquid RMGI to reduce fluid flow through human dentin, compared to an established single-bottle nanofilled total etch resin adhesive indicated for root desensitization.

METHODS

Dentin permeability was measured on human crown sections on etched dentin, presenting a model for the exposed tubules typical of root sensitivity, and permitting measurement of the maximum permeability. In the first two groups, the etched dentin was coated with either the RMGI or adhesive, and permeability measured on the coated dentin. In a third group, a smear layer was created on the dentin with sandpaper, then the specimens were coated with the RMGI; permeability was measured on the smeared and coated dentin. Specimens from each group were sectioned and examined via scanning electron microscopy (SEM).

RESULTS

Both the resin adhesive and the new paste-liquid RMGI protective material significantly reduced fluid flow through dentin, and exhibited excellent seal on dentin with either open tubules or smear-layer occluded tubules. The RMGI infiltrated the smear layer with resin during placement, penetrated dentin tubules, and formed resin tags.

SIGNIFICANCE

The RMGI was equivalent to the adhesive in its ability to reduce fluid flow and seal dentin. It is therefore concluded that the new RMGI and the adhesive show the potential to offer excellent sensitivity relief on exposed root dentin.

Effect of a new liner/base on human dentin permeability

OBJECTIVES

Resin-modified glass ionomers (RMGI) have demonstrated clinical success in their ability to minimize post-operative sensitivity of restorations. RMGIs have been recently introduced as paste-liquid systems for convenience of clinical usage. The objective of this study was to measure the ability of a new paste-liquid RMGI liner/base to reduce fluid flow through human dentin.

METHODS

Dentin permeability was measured on human crown sections on etched dentin, using etched dentin as a model for the exposed tubules typical of root sensitivity, and permitting measurement of the maximum permeability. In the one group, the etched dentin was coated with the RMGI, and pre- and post-treatment permeability was measured on the coated dentin. In the second group, a smear layer was created on the dentin with sandpaper, then the samples were coated with the RMGI; permeability was measured on the smeared and coated dentin. Samples from each group were sectioned and examined via scanning electron microscopy (SEM).

RESULTS

The new paste-liquid RMGI liner/base significantly reduced fluid flow through dentin, and exhibited excellent seal on dentin with either a smear layer or open tubules. SEM images show evidence that the RMGI infiltrated the smear layer with resin during placement, penetrated dentin tubules, and formed resin tags in acid-etched dentin.

CONCLUSIONS

Based on these results, combined with previous research on adhesion and microleakage, it is concluded that the new RMGI liner/base should minimize post-operative sensitivity in restorations.

Clinical and microbiological performance of resin-modified glass-ionomer liners after incomplete dentine caries removal

The aims of this study were to evaluate clinically and microbiologically the effects of two resin-modified glass-ionomer cements (RMGICs) used as liners after incomplete dentine caries removal and to identify Streptococcus mutans and Streptococcus sobrinus strains isolated from dentine samples, before and after indirect pulp treatment. Twenty-seven primary molars with deep carious lesions, but without signs and symptoms of irreversible pulpitis, were submitted to indirect pulp treatment. Treatment consisted of incomplete excavation of the carious dentine, application of one of the RMGICs (Vitrebond or Fuji Lining LC) or calcium hydroxide cement (Dycal), and sealing for 3 months. Clinical evaluation (consistency, color, and wetness of dentine) and carious dentine collects were performed before temporary sealing and after the experimental period. Microbiological samples were cultivated in specific media for subsequent counting of mutans streptococci (MS) and lactobacilli (LB). MS colonies were selected for identification of S. mutans and S. sobrinus by polymerase chain reaction. After 3 months, the remaining dentine was hard and dry, and there was a significant decrease in the number of MS and LB, in all groups, although complete elimination was not achieved in 33% and 26% of the teeth for MS and LB, respectively. From 243 MS colonies selected, 216 (88.9%) were identified as S. mutans and only 2 (0.8%) as S. sobrinus. The use of resin-modified glass-ionomer liners after incomplete caries removal, as well as a calcium hydroxide cement, promoted significant reduction of the viable residual cariogenic bacteria in addition to favorable clinical changes in the remaining carious dentine.

Effects of a self-etching resin coating system to prevent demineralization of root surfaces

OBJECTIVES

The purpose of this study was to evaluate the ability of an experimental self-etching resin coating system to protect against demineralization of the root surface in vitro, comparing its effectiveness with two commercial one-step self-etching adhesives.

METHODS

The experimental resin coating system (EC), consisting of a self-etching primer and an acrylate-based resin, or the two commercial self-etching adhesives, Adper Prompt-L Pop (AD) and Clearfil Tri-S Bond (S3), was applied to the cementum of a human extracted tooth root. The specimens were immersed in acetate buffer at pH 5.5 for 4 weeks, and the degree of demineralization underneath the materials was evaluated by microscopic observation and contact microradiography. Each material's sealing and interfacial ultrastructure on the cementum was morphologically examined by scanning electron microscopy, and their bonding ability to cementum was determined by microtensile bond strength (MTBS) tests.

RESULTS

Application of AD and S3 showed limited effects to protect against demineralization, but no demineralization was observed for EC. EC showed greater coating thickness than the other two materials, with formation of integral hybridized layers with cementum. Although the MTBS values for EC were significantly lower than those for AD and S3, cohesive failure in resins was the prevalent fracture mode for EC, showing no possible disadvantages in bonding ability.

SIGNIFICANCE

The experimental resin coating system effectively prevented acid demineralization on root surfaces due to its ability to produce an appropriately thick coating and an integral hybridized layer.

Ion uptake into demineralized dentine from glass ionomer cement following pretreatment with silver fluoride and potassium iodide

BACKGROUND

Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been shown to provide a pronounced antimicrobial action against caries. The clinical application of this material has been limited by the staining associated with both teeth and tooth coloured restorative materials. The application of potassium iodide (KI) after AgF eliminates stain formation. The purpose of this study was to determine if a prior application of silver fluoride and potassium iodine to demineralized dentine affected the uptake of strontium and fluoride from a glass ionomer cement restoration.

METHOD

Three cavities were prepared in each of five recently extracted human third molars. The cavities were demineralized and treated as follows. In each tooth, one cavity was left as a control, one cavity was restored with glass ionomer cement and one cavity was treated with 1.8M AgF and a saturated KI solution and then restored with glass ionomer cement. The penetration of the various elements into demineralized dentine was measured by their relative percentage weights using electron probe microanalysis (EPMA).

RESULTS

Fluoride uptake was significantly higher in the AgF and KI treated samples compared to the other two samples and significantly higher in the glass ionomer restored sample compared to the control. The application of AgF and KI did not significantly interfere with the transfer of strontium from glass ionomer cement into dentine. Silver and iodine deposits were present in the demineralized dentine treated with AgF and KI.

CONCLUSIONS

The application of AgF and KI onto dentine prior to the placement of glass ionomer cement did not significantly affect the strontium uptake into the subjacent demineralized dentine and the fluoride levels in this zone were significantly increased.

Comparative assessment of hardening of demineralized dentin under lining materials using an ultramicroindentation system

The aim of the current in vitro study was to evaluate the influence of three lining materials with a reported mineralizing capacity on hardness and elasticity of demineralized dentin. Four standardized microcavities were prepared in exposed dentin surfaces of 16 extracted human molars each. Dentin was demineralized in 0.5M EDTA for 2 h. One microcavity was left empty. The others were filled with a resin-modified glass ionomer cement (RMGIC), a bioactive glass S53P4 suspension, and a prototype Ca-PO(4) cement. Teeth were then immersed in deionized water or simulated oral fluid. After 3 weeks, hardness and composite elastic modulus of the dentin subjacent to the microcavities were assessed under wet conditions using the ultramicroindentation system (UMIS). After immersion in deionized water, there was no significant improvement of the mechanical properties of dentin irrespective of the material applied beforehand, indicating a lack of direct material effects. Exposure to simulated oral fluid resulted in significantly (p < 0.05) higher hardness and composite elastic modulus values of the dentin subjacent to empty microcavities and counterparts lined with bioactive glass compared to corresponding dentin under the RMGIC. UMIS profiles showed little variance.

Enhancement of fluoride release from glass ionomer cement following a coating of silver fluoride

BACKGROUND

This study investigated the extent to which a coating of 10% silver fluoride (AgF) on discs of glass jonomer cements (GIGs) would enhance the release of fluoride ion into eluting solutions at varying pH.

MATERIALS AND METHODS

Forty discs each of Fuji LX, Fuji VII and of Vitrebond were prepared in a plastic mould. Twenty discs of each material were coated for 30 seconds with a 10% solution of AgF. Five discs each of coated and uncoated material were placed individually in 4m1 of differing eluant solutions. The eluant solutions comprised deionized distilled water (DDW) and three separate acetate buffered solutions at pH 7, pH 5 and pH 3. After 30 minutes the discs were removed and placed in five vials containing 4m1 of the various solutions for a further 30 minutes. This was repeated for further intervals of time up to 216 hours, and all eluant solutions were stored. Fluoride concentrations in the eluant solutions were estimated using a fluoride specific electrode, with TISAB IV as a metal ion complexing and ionic concentration adjustment agent. Cumulative fluoride release patterns were determined from the incremental data.

RESULTS

The coating of AgF greatly enhanced the level of fluoride ion release from all materials tested. Of the uncoated samples, Vitrehond released the greater concentrations of fluoride ion, followed by Fuji VII. However, cumulative levels of fluoride released from coated samples of the GICs almost matched those from coated Vitrebond.

CONCLUSIONS

It was concluded that a coating of 10% AgF on GICs and a resin modified GIC greatly enhanced the concentration of fluoride released from these materials. This finding might be applied to improving protection against recurrent caries, particularly in high caries risk patients, and in the atraumatic restorative technique (ART) of restoration placement.

Influence of 0.05% sodium fluoride solutions on microhardness of resin-modified glass ionomer cements

This study aimed to evaluate the influence of fluoride-containing mouthrinse solutions (Fluorgard and Oral B) on the superficial microhardness of two resin-modified glass ionomer cements (Vitremer and Fuji II LC). Fifteen discs-shaped specimens of each glass ionomer cement (Ø10 mm; 2 mm thick) were prepared, thereby forming two groups. After 24-hour storage in artificial saliva, the microhardness was measure and the data were recorded. Next, each group was divided into three subgroups (n = 5), according to the solution to be immersed in. Control specimens were kept in artificial saliva along the whole experiment. The test specimens were kept in mouthrinse solution for 30 days. Vickers surface microhardness was analyzed at predetermined evaluation periods: 24 h, 48 h, 7, 14, 21 and 30 days after specimens' preparation. Data were subjected to three-way ANOVA and to Tukey test (p<0.05). A better behavior of Fuji II LC was observed and Fluorgard affected most the characteristics of the tested materials. It may be concluded that fluoride-containing solutions influenced the tested characteristics of materials, mainly of Vitremer.

Adhesive systems and secondary caries formation: Assessment of dentin bond strength, caries lesions depth and fluoride release

OBJECTIVES

The present study evaluated the microtensile bond strength and caries formation on adhesive/dentin interfaces before and after dynamic chemical formation of secondary caries.

METHODS

Restorations were prepared on the dentin surface of 80 bovine incisors using four adhesive systems: two fluoride-free (Single Bond and Clearfil SE Bond) and two fluoride containing (Optibond Solo Plus and Clearfil Protect Bond). The restored teeth were then sectioned into multiple slabs that were further trimmed at the bonded interface to a cross-sectional area of 1 mm2. Half of the slabs were subjected to secondary caries formation using a pH cycling model (treated groups); while the other half was used as the control group (no pH cycling). The specimens designated for bond strength evaluation were subjected to microtensile bond strength test (muTBS). Caries lesions formation was assesses by polarized light microscopy at different depths from the adhesive-dentin bonded interface. The fluoride ion concentration was evaluated using the de/remineralization solutions (De/Re).

RESULTS

No differences in muTBS were observed among the adhesive systems in both the control and treated conditions. Secondary caries significantly reduced the values of muTBS for all adhesives (p<0.05). Optibond Solo Plus presented the lowest caries formation at 5 microm depth. Fluoride concentrations present in the De/Re were less than 0.03 ppm, regardless of the adhesive system tested.

SIGNIFICANCE

Bond strength values significantly decreased after in vitro secondary caries formation. Fluoride present in adhesive systems is not capable of inhibiting secondary caries or maintaining bond strength values following caries formation.

Review on fluoride-releasing restorative materials--fluoride release and uptake characteristics, antibacterial activity and influence on caries formation

OBJECTIVES

The purpose of this article was to review the fluoride release and recharge capabilities, and antibacterial properties, of fluoride-releasing dental restoratives, and discuss the current status concerning the prevention or inhibition of caries development and progression.

METHODS

Information from original scientific full papers or reviews listed in PubMed (search term: fluoride release AND (restorative OR glass-ionomer OR compomer OR polyacid-modified composite resin OR composite OR amalgam)), published from 1980 to 2004, was included in the review. Papers dealing with endodontic or orthodontic topics were not taken into consideration. Clinical studies concerning secondary caries development were only included when performed in split-mouth design with an observation period of at least three years.

RESULTS

Fluoride-containing dental materials show clear differences in the fluoride release and uptake characteristics. Short- and long-term fluoride releases from restoratives are related to their matrices, setting mechanisms and fluoride content and depend on several environmental conditions. Fluoride-releasing materials may act as a fluoride reservoir and may increase the fluoride level in saliva, plaque and dental hard tissues. However, clinical studies exhibited conflicting data as to whether or not these materials significantly prevent or inhibit secondary caries and affect the growth of caries-associated bacteria compared to non-fluoridated restoratives.

SIGNIFICANCE

Fluoride release and uptake characteristics depend on the matrices, fillers and fluoride content as well as on the setting mechanisms and environmental conditions of the restoratives. Fluoride-releasing materials, predominantly glass-ionomers and compomers, did show cariostatic properties and may affect bacterial metabolism under simulated cariogenic conditions in vitro. However, it is not proven by prospective clinical studies whether the incidence of secondary caries can be significantly reduced by the fluoride release of restorative materials.

Inhibition of cultivable bacteria by chlorhexidine treatment of dentin lesions treated with the ART technique

The aim of this study was to examine the changes in the cultivable microflora of carious dentin before and after atraumatic restorative treatment (ART) and investigate the inhibitory effect of chlorhexidine-gluconate-based cavity disinfectant in the microflora. Using a split mouth design, 35 primary molar pairs with class II carious lesions in 35 patients (mean age 7.31+/-0.47 years) were selected. The total viable counts (TVC), Streptococcus mutans and lactobacilli were first measured in the center of the infected demineralized lesion and then from the hard dentine after caries removal by the ART technique. Chlorhexidine-gluconate (2%)-based cavity disinfectant was applied to one of the molar pairs and the other molar received no disinfectant treatment. Thereafter, all of the teeth were restored with glass ionomer cement (GIC). Cavities were reassessed after 6 months and again dentine samples were microbiologically investigated. Removal of carious dentine by ART significantly reduced TVC, S. mutans and lactobacilli. After 6 months, application of chlorhexidine exhibited a greater significant reduction in TVC (p=0.013), and a significant reduction in S. mutans compared to the nondisinfected group (p<0.001). A significant reduction in lactobacilli counts was observed in both groups after 6 months, but the difference between the disinfected and nondisinfected groups was not significant (p=0.056). ART was found to be effective in reducing the cultivable microflora and chlorhexidine-gluconate-based cavity disinfectant might serve as a suitable additional agent in inhibiting the residual bacteria in the dentine.

Fluoride-containing restorative materials

Dental practitioners are exposed to an increasing number of dental materials, which claim the benefits of fluoride release. The purpose of this paper is to critically review the literature of these materials. Glass ionomers, resin modified glass ionomers, compomers, resin composites, fissure sealants and amalgam are discussed. It is clear that a long-term measurable release of fluoride can be observed from certain restorative materials, in vitro, particularly glass ionomer cement, resin modified glass ionomer cement, fluoridated cements, fluoridated dental amalgam and certain fissure sealants. In general, the rate of fluoride release is not constant but exhibits a relatively rapid initial rate, which decreases with time. However, the fluoride release profiles may be dependent on specific formulation and on experimental design and sampling methods. These materials may feature greater longevity, a reduced incidence of marginal failure, an elevated concentration of fluoride in contingent plaque, together with an antibacterial action when compared with non-fluoride releasing materials. In addition, fluoride-releasing materials may perform better in caries inhibition in artificial caries model studies than non-fluoridated materials. While any, or all, of these anti-cariogenic effects may be associated with fluoride release, a direct relationship between fluoride release profiles and such effects has not been determined in vivo.

Evaluation of a New Fluoride-releasing One-step Adhesive

In this study, a newly developed S-PRG (surface pre-reacted glass-ionomer) filler-containing one-step adhesive, called SI (SI-IB551, Prototype), was evaluated regarding its fluoride release behavior. As a result, fluoride ion distribution in the tooth structures and acid resistance of cavity margins were also evaluated. In addition, Absolute (a fluoride-releasing one-step adhesive; AB) was evaluated in comparison to G-Bond (a non-fluoride-releasing one-step adhesive; GB) which was used as a negative control. Concentration of fluoride released was measured using a fluoride ion selective electrode after immersion of each material in distilled water. Fluoride distribution in tooth-adhesive interfacial areas was examined with EPMA following cavity preparation in human premolars and having treated resin restorations with each material. To evaluate acid resistance, restored specimens were immersed in an acetic acid buffer (0.2 M, pH 4.5) for 12 hours and then the cavity margins were observed using scanning electron microscopy. Amounts of fluoride released from AB and SI were significantly greater than that from GB. Further, significant differences in fluoride release were detected between AB and SI. A layer of increased fluoride density was clearly detected at the enamel- and dentin-SI interfaces. In terms of acid resistance, an acid resistance zone was also formed adjacent to the tooth-adhesive interface of AB and SI specimens. However, in GB specimen, acid resistance zone was not observed. These findings suggested that one-step adhesives displayed a favorable fluoride release property, thereby contributing positively to inhibition of recurrent caries.

Advances in glass-ionomer cements

This article describes the properties, advances and shortcomings of glass-ionomer cement as a restorative material. The adhesion of glass-ionomer to tooth structure is less technique sensitive than composite resins and its quality increases with time. Therefore glass-ionomer might turn out to the more reliable restorative material in minimal invasive dentistry based on adhesive techniques.

Effect of fluoride-releasing filling materials on underlying dentinal lesions in vitro

Fluoride-releasing materials placed over carious tissue are assumed to enhance remineralisation of the underlying lesion. This remineralisation, however, also depends on the availability of calcium and phosphate, which may be supplied by the pulpal fluid. The aim of this study was to measure the fluoride release of glass ionomer cements (GICs) into underlying dentin and to measure the effect of the released fluoride on the remineralisation of the underlying dentinal lesions using transversal microradiography. Discs of fluoride-releasing GIC were placed on top of dentinal lesions in an in vitro model. The discs and the dentin slabs were covered completely by a protective layer of nail varnish, leaving only the pulpal side of the dentin slab open, and hence the dentinal tubules as the pathway for the incubation fluid to the GIC disc. Specimens were incubated in a remineralisation buffer. The materials tested were a conventional GIC, an experimental GIC that was designed to have a high fluoride release, and an inert material. Fluoride was found to penetrate through the dentin slab into the surrounding fluid. Fluoride uptake from the experimental GIC was higher than from the conventional GIC. Mineral content-depth profiles after 10 weeks' remineralisation revealed that in the outer 30 microm of the lesion a higher mineral deposition occurred for the experimental GIC than in both other groups. No differences in the overall change of integrated mineral loss were found for the tested materials. We conclude that high fluoride release from filling materials only results in superficially increased remineralisation of underlying demineralised dentin.

Microhardness of dentine underlying ART restorations in primary molars: an in vivo pilot study

OBJECTIVE

To evaluate the microhardness of dentine underlying glass ionomer restorations made with Atraumatic Restorative Treatment.

DESIGN

An experimental single-centre study.

SETTING

University Department, Brazil, 2001.

MATERIALS AND METHODS

Sixteen children were selected showing primary molars containing carious cavities (n = 29), which were restored using Fugi IX. Subsequently, some teeth were extracted respecting Nolla stage 7 or 8 of the permanent successor, and categorised according to the post-restoration time in the mouth: G1 (baseline, immediate extraction), G2 (30 days), G3 (90 days) and G4 (180 days). Four teeth were excluded because they were not in time of normal exfoliation. The 25 extracted teeth were resin embedded, sectioned mesiodistally and prepared metallographically. Knoop microhardness analysis (Micromet 2003; 10g for 1.5 sec.) produced identations in three areas of dentine: Zone 1 (just below the restoration), Zone 3 (as close as possible to the pulp) and Zone 2 (intermediate region between 1 and 3). Non-parametric statistical tests were done--at a significance level of 5%.

RESULTS

Four teeth were excluded. No significant difference was noted among the zones, inside the groups. Zones 1 and 2 showed a considerable increase of microhardness according to the time, except for Group 3 (p > 0.05).

CONCLUSION

Although microhardness had increased, it was not sufficiently equal to the microhardness of the healthy dentine, regardless of the depth evaluated.

The short-term in situ model to evaluate the anticariogenic potential of ionomeric materials

OBJECTIVES

Aiming to contribute to the study of mechanisms involved in the anticariogenic properties of dental materials, this study assessed the suitability of a short-term in situ model to evaluate the anticariogenic potential of ionomeric materials.

METHODS

The study used a 3-phase crossover, double blind design, and in each phase eight volunteers wore palatal appliances containing four enamel blocks restored with one of the following materials: composite resin (CR-Z250) (negative control), a conventional glass ionomer cement (GIC-Ketac-Fil) or a resin-modified GIC (RM-GIC-Vitremer). The restored blocks were covered with a "test plaque" of S. mutans, placed in palatal appliances and a cariogenic challenge was made during 1 min with 20% sucrose solution. After 45 min, test plaque was collected for fluoride (F) analysis. Enamel surface microhardness was previously determined at one side of the restoration and the percentage of surface microhardness change (%SMC) in relation to baseline (other side) was calculated. F concentration in enamel was also evaluated.

RESULTS

Split-plot ANOVA showed a statistically lower %SMC on enamel around the ionomeric materials than around the CR (p<0.05). This result was supported by a statistically higher F concentration in test plaque (P<0.001) and in enamel (P<0.001) restored with the ionomeric materials when compared to the CR.

CONCLUSIONS

The results suggest that the short-term in situ model tested is useful for studying the anticariogenic potential of dental materials that release fluoride.

Effect of a Hydroxyl Ion-Releasing Composite Resin on Plaque Acidogenicity

The aim of this in vivo study was to evaluate the neutralizing capacity, registered as change of plaque acidogenicity, on aged proximal restorations of an ion-releasing composite resin (IRCR), which releases hydroxyl, calcium, and fluoride ions at low pH. Twenty patients, with a mean age of 63 years (range 43-85), participated. All had one aged proximal IRCR restoration (mean age 15 months) and one nonrestored enamel surface to make an intraindividual comparison possible. The neutralizing effect of the IRCR was evaluated by measuring plaque pH, using the microtouch method, after a mouthrinse with 10% sucrose. The plaque pH measurements were repeated 1.5 years later on the IRCR (mean age 34 months), the enamel surfaces and a universal hybrid composite resin (CR). At both 15 and 34 months, the plaque on the IRCR surfaces showed the least acidogenic potential for the whole 60-min time interval. The largest differences between the IRCR, CR and enamel were found during the first 15 min. At 15 months, the total areas under the plaque pH curve (AUC(5.7) and AUC(6.2)) differed significantly between the IRCR and enamel surfaces for the time periods 0-5 min and 5-15 min. At 34 months, significant differences were found between IRCR and CR at the 0- to 5-min time period. It can be concluded that IRCR restorations countered the plaque pH fall and maintained it at levels where less enamel and dentin demineralization can occur.

Levels of mutans streptococci and lactobacilli in plaque on aged restorations of an ion-releasing and a universal hybrid composite resin

The purpose of this in vivo study was to evaluate the cariogenic microflora of plaque on aged restorations of a hydroxyl, fluoride, and calcium ion-releasing composite resin (IRCR) (Ariston pHc), and to compare it intra-individually with a universal hybrid composite resin and enamel. Each of 19 subjects received one proximal restoration of the IRCR, one proximal universal hybrid composite resin restoration (CR) and each subject had one non-filled proximal enamel control surface to make intra-individual comparisons possible. To avoid peak ion releases from the materials, aged restorations were studied. Plaque was collected from 57 surfaces using sterile applicator tips. Samples were cultured to determine the numbers of mutans streptococci, lactobacilli, and total microorganisms. The relative numbers for mutans streptococci (% of total bacteria) were: IRCR 0.59%, CR 0.40%, enamel 0.22%. Two outliers were found in the IRCR group. Excluding these outliers resulted in a relative number of 0.33%. Lactobacilli were detected in the plaque from only 9 surfaces and at very low relative proportions for all three surfaces: 0.01%. The enamel surfaces showed the lowest relative numbers of mutans streptococci and lactobacilli, but the differences were not significant. It can be concluded that the ion release of the IRCR did not influence the growth of cariogenic microorganisms in dental plaque.

Influence of the mineral content and morphological pattern of artificial root caries lesion on composite resin bond strength

Dentine substrates with different mineral contents and morphological patterns were created by submitting root slabs to the following treatments: (A) immersion in artificial saliva during the experimental period (control), (B) demineralization for 32 h to induce caries lesion (demineralized group), and (C) demineralization for 32 h followed by remineralization for 8 d (remineralized group). The slabs were longitudinally sectioned, the mineral content was determined by cross-sectional microhardness, and the bond strength of an adhesive system/composite resin was assessed using a microtensile bond strength test. The dentine morphology after the treatments as well as the failure pattern of the debonded specimens was examined by scanning electron microscopy. Statistically significant differences were found in mineral content. Morphological analysis showed marked differences between the patterns of demineralized and remineralized substrates. The bond strength mean value of the control A did not differ from the group B, but was statistically higher than the group C. Since no linear relationship was found between dentine mineral content and bond strength values, it could be suggested that the morphological pattern may be more relevant than the mineral content to explain the bond strength of composite resin to dentine.

Inhibition of demineralization in vitro around fluoride releasing materials

Replacement of restorations because of secondary caries is a continuing problem in restorative dentistry. This investigation assessed the capacity of fluoride-releasing restorative materials to resist caries in vitro when used in roots. Class 5 cavities were prepared in buccal and lingual surfaces of 30 extracted premolars and restored with one of three polyacid modified resin composites (F-2000, Hytac and Compoglass F), a resin modified glass-ionomer cement (Fuji II LC) a conventional glass ionomer (Ketac-Fil), and a resin composite (Z-100). After 5 weeks in an acid gel for caries-like lesion formation, the teeth were sectioned longitudinally and examined with polarized light. The results showed that restoration of caries with polyacid modified resin composites and resin modified glass ionomer cements may be of great importance in the prevention of secondary caries around the restorations in roots. Clinical Relevance Light cured fluoride-releasing restorations may inhibit caries-like lesions. Inhibition of demineralization in vitro around fluoride releasing materials.

Toughness, bonding and fluoride-release properties of hydroxyapatite-added glass ionomer cement

Improving the mechanical strength of glass ionomer cement while preserving its favorable clinical properties such as fluoride release, bonding to tooth structure and biocompatibility is desirable. In this study, hydroxyapatite was incorporated into chemically setting glass ionomer cement and its effect on the fracture toughness, bonding to dentin and fluoride release was identified. Commercial glass ionomer cement (Fuji IX GP((R)) ) was the control and base material. Eight weight percent of hydroxyapatite was added into the glass ionomer powder. Specimens were fabricated and the fracture toughness, shear bond strength and eluted fluoride ion concentration were measured. Adding hydroxyapatite into the glass ionomer cement led to significantly higher fracture toughness after 15min and 24h from mixing. The hydroxyapatite-added cement also exhibited bond strength to dentin similar to that of the control from 15min to 56 days and consistent fluoride release for 13 weeks. SEM findings showed a cohesive type of fracture in the material for all specimens in both groups. These results indicate that hydroxyapatite-added glass ionomer cement has a potential as a reliable restorative material with improved fracture toughness, long-term bonding to dentin and unimpeded ability of sustained fluoride release.

Surface roughening of glass ionomer cements by neutral NaF solutions

The objective of this study was to investigate the effect of repeated applications of a neutral NaF solution on the surface roughness of four conventional glass ionomer cements (GIC) (ChemFil Superior encapsulated, Fuji Cap II, Ketac-Fil and Hi Dense), three resin-modified (RM-) GIC (Fuji II LC encapsulated, Photac-Fil and Vitremer) and one polyacid-modified composite resin (PAM-C) (Dyract). Matured specimens were four times alternately eluted in water and exposed to 2% neutral NaF aqueous solutions for 1h. Control specimens were only subjected to elution in water for the same time period. After the treatment the surface roughness R(a) was determined using non-contact surface profilometry and selected samples were examined with SEM. Except for the PAM-C, R(a) increased drastically for the fluoride-treated samples compared to water-stored samples, the effect being most pronounced for the GIC. Surface roughening apparently is caused by a progressive disintegration or chemical erosion of the polysalt matrix of (RM-)GIC.

Microbiological assessment of saliva from children subsequent to atraumatic restorative treatment (ART)

AIMS

The aim of this study was to evaluate mutans streptococci (MS) in the saliva following use of the atraumatic restorative treatment (ART) technique.

METHODS

Sixteen 5-7-year-old children had restorations using the ART technique and employing FUJI IX glass-ionomer cement as the restorative material. Decayed tissue was manually excavated without local anaesthesia, being careful to avoid discomfort. Saliva was collected for microbiological assessment using Kit Caritest MS before treatment, one week, four weeks and one year after ART was used. The procedure for saliva collection, incubation, storage, and comparative reading of MS counts followed the manufacturer's instructions. The data were statistically analysed, using non-parametric tests (Wilcoxon Signed Ranks and Sign Test) at a significance level of 0.05.

RESULTS

The results showed a significant reduction of MS levels in saliva when comparing the results before treatment with those obtained one week (95.95%; P = 0.003), four weeks (93.27%; P = 0.000) and one year (95.56%; P = 0.002) after ART.

CONCLUSIONS

It is concluded from the results that the ART technique proved satisfactory and appeared to have produced a significant and sustained reduction in levels of MS. These results need to be confirmed in a larger study.

Effect of fluoride-releasing adhesive system on decalcified dentin

The aim of this study was to evaluate the effect of fluoride-releasing adhesive systems on human decalcified dentin in vitro. Two fluoride-releasing adhesive systems, Reactmer bond (RB, Shofu) and ABF (AF, Kuraray), an experimental system, and a commercial adhesive system without fluoride release, SE bond (SE, Kuraray), were used in this study. The amount of fluoride release from adhesive in deionized water was measured every week for 10 weeks. Class V cavities were prepared on extracted human pre-molars and decalcified dentin was promoted by using a bacterial caries induction system at the cavity floor. The cavities preserving decalcified dentin were restored with resin composite (AP-X, Kuraray) after treatment by each adhesive system. The specimens without treatment by adhesive system and restoration were used for control. The specimens with restoration were then incubated for 4 weeks at 37 degrees C, 100% humidity. Microradiographs of the specimens showed that the radiopacities of the decalcified dentin layers in RB and AF groups with fluoride release were significantly higher than those in SE or control groups without fluoride release. This result suggested that the fluoride-releasing adhesive systems enhanced mineralization of decalcified dentin.

Effect of smear layer on root demineralization adjacent to resin-modified glass ionomer

The cariostatic effect of resin-modified glass ionomer (RMGI) on secondary root caries is well-documented. However, this beneficial effect may be dependent upon the mode of cavity surface treatment. To investigate this relationship, we studied 4 cavity surface treatments prior to the placement of RMGI: no treatment (None), polyacrylic acid (PAA), phosphoric acid (H(3)PO(4)), and Scotchbond Multi-Purpose adhesive (SMP) as a control. Specimens were aged for two weeks in synthetic saliva, thermocycled, and subjected to an artificial caries challenge (pH 4.4). Polarized light microscopy (PLM) and microradiography (MRG) showed significantly less demineralization with the H(3)PO(4) cavity surface treatment as revealed by ANOVA and Tukey's multiple comparisons (p < or = 0.05). Dentin fluoride profiles determined by electron probe microanalysis (EPMA) supported PLM and MRG findings. It may be concluded that removal of the smear layer with phosphoric acid provides significantly enhanced resistance to secondary root caries formation adjacent to RMGI restorations.

Effects of tooth-conditioning agents on bond strength of a resin-modified glass-ionomer sealant to enamel

OBJECTIVES

The purpose of this study was to evaluate the effects of tooth-conditioning agents on bond strength of resin-modified glass-ionomer sealant (Fuji III LC) to bovine enamel as well as on dissolution of calcium ions from the bovine enamel surfaces.

METHODS

The enamel surfaces of bovine lower incisors were treated with 10 and 20% polyacrylic acid, 12% citric acid and 35% phosphoric acid for 20s. Fuji III LC was applied to the etched enamel surfaces, and the shear bond strength of each specimen was measured using an Instron Universal Testing Instrument. The amounts of calcium ions dissolved from the treated enamel surfaces were also measured using a polarized Zeeman atomic absorptiometer.

RESULTS

In specimens pretreated with distilled water, 10% polyacrylic acid, 20% polyacrylic acid, 12% citric acid and 35% phosphoric acid, the mean values of shear bond strength were 5.5, 12.5, 15.2, 15.2 and 15.1MPa, respectively, and the amounts of Ca(2+) dissolved from the enamel surfaces were 5.6, 41.4, 88.5, 131.6 and 588.3 microg/cm(2), respectively.

CONCLUSIONS

The adhesion of a resin-modified glass-ionomer sealant to bovine enamel was significantly improved by the use of tooth-conditioning agents. Especially, treatment of an enamel surface with 20% polyacrylic acid results in good shear both strength and relatively small degree of enamel erosion.

In vivo vs in vitro anticariogenic behavior of glass-ionomer and resin composite restorative materials

OBJECTIVE

To evaluate the in vivo vs the in vitro anticariogenic potential of glass-ionomer and resin composite restoratives, utilizing a standardized interfacial gap model.

METHODS

(a) In vitro study. Box shaped cavities were prepared at the buccal surfaces of extracted premolars limited to enamel. The incisal cavity walls received no treatment and were covered with 40 microm-thick metal spacers. The cavities were restored with a glass-ionomer (Ketac-Fil, n=8) and a fluoride-free resin composite (Scotchbond MP Plus/Z100, n=8). After 4 weeks immersion in an acidic gel (pH 4), thin sections were produced and examined under polarized-light microscopy.(b) In vivo study. Four low caries activity volunteers, with first four premolars, each planned to be extracted for orthodontic reasons, participated in the study. Cavities were prepared as before and filled contralaterally per patient with glass-ionomer (n=8) and resin composite (n=8). After 6 months in vivo, the teeth were extracted, sectioned and investigated by polarized-light microscopy, Raman microspectroscopy and SEM-EDS X-ray microanalysis. Unpaired t-test (lesion dimensions) and one-way ANOVA and Newman-Keuls tests (Ca, P wt%, Ca/P ratios) were used to identify statistically significant differences in lesion analysis (alpha=0.05).

RESULTS

(a) In vitro study. All restorations developed lesions at incisal and cervical margins. At gap-free regions glass-ionomers showed reduced lesion dimensions compared to those of composites (p<0.05). At regions with gaps, no significant differences were found in lesion depth between the restorative groups tested. Lesion length was increased in composite, and decreased in glass-ionomer, whereas lesion depth in both restorative groups was increased in comparison to gap-free regions (p<0.05).(b) In vivo study. No lesions were observed at gap-free regions. At gap regions, 75.5% of glass-ionomer and 62.5% of composite restorations developed lesions. The lesion dimensions were significantly greater in glass-ionomer (p<0.05). A reduction in PO4(3-), CO3(2-), Ca and P was found in lesions compared to intact tissues. No F was detected and no CaF2 lattice vibrations were found at the enamel margins facing the gap adjacent to glass-ionomers.

SIGNIFICANCE

In the presence of a standardized interfacial gap, no preventive effect was exerted in vivo from the glass-ionomer to protect the adjacent enamel wall from secondary caries attack. The lack of any correlation between the in vivo and in vitro models tested implies that artificial caries experiments have a negligible clinical relevance in predicting the in vivo effect.

Effect of fluoride application on tensile bond strength of self-etching adhesive systems to demineralized dentin

STATEMENT OF PROBLEM

It has been reported that the bond strength of composite to demineralized dentin is lower than that to sound dentin. This can be a problem in the success of so-called sealed restorations.

PURPOSE

The aim of this study was to evaluate the effect of fluoride application on the tensile bond strength of self-etching adhesive systems to demineralized dentin.

MATERIAL AND METHODS

One hundred twenty extracted bovine incisors were ground flat with 600-grit silicone carbide paper. Ninety teeth were then immersed in acetate buffer (pH 4.0) to form demineralized dentin. These teeth were randomly divided into 3 groups of 30 each: surfaces treated with fluoride solution (Group NF), surfaces treated with fluoride solution followed by a water rinse (Group RF), and control surfaces with no pretreatment (Group C). The remaining 30 teeth comprised a group with normal dentin surfaces (Group S). Each group was further divided into 3 subgroups of 10 each to test the bond strength test of Clearfil SE Bond, Unifil Bond, and Mac-Bond II. Tensile bond strengths (in MPa) were measured with a universal testing machine at a crosshead speed of 0.5 mm/min. Mean bond strengths were analyzed by 2-way analysis of variance and Fisher's PLSD (P =.05). SEM observations of the surfaces before and after priming and at resin-dentin interfaces in each group were performed. Elemental analysis of the dentin surfaces before priming was also carried out.

RESULTS

The bond strengths of the adhesives to demineralized dentin in Groups NF, RF, and C were significantly lower than that of the normal dentin in Group S (P <.05). The mean bond strengths of the 3 adhesives in Group NF were higher than those in Groups RF and C, but a significant difference was observed only when Clearfil SE Bond was used (P <.05). In SEM images the open dentinal tubules on the surface and the resin tag formation at the resin-dentin interface were apparent in Group NF but were not observed in Groups RF and C. On elemental analysis, considerable amounts of fluoride and calcium were detected in the surfaces of Group NF.

CONCLUSION

Within the limitations of this study, the surface treatment with fluoride solution supported the resin tag formation at the resin-dentin interface and slightly improved the bond strength of the self-etching adhesive systems tested to demineralized dentin. This result indicated that the fluoride treatment to demineralized dentin might contribute to the success of the sealed restoration.

Fluoride-releasing restorative materials and secondary caries

Secondary caries are responsible for 60% of all replacement restorations in the typical dental practice. Risk factors for secondary caries are similar to those for primary caries development. Unfortunately, it is not possible to predict accurately which patients are at risk for restoration failure. Fluoride-releasing dental materials provide for improved resistance against primary and secondary caries in coronal and root surfaces and have become a part of the dentist's armamentarium. This article discusses the improvement in the properties of dental materials with the ability to release fluoride. It is anticipated that in the near future, the vast majority of restorative procedures will employ fluoride-releasing dental materials as bonding agents, cavity liners, luting agents, adhesives for orthodontic brackets, and as definitive restoratives.

Selection of restorative materials for the atraumatic restorative treatment (ART) approach: a review

The atraumatic restorative treatment (ART) technique or approach for the restoration of primary and permanent teeth has been widely adopted in, but not limited to, developing countries. However, the requirement for the placement of the restorative materials under often less-than-ideal conditions imposes significant restrictions on their selection; and there have been very few randomized clinical trials or reports comparing different types of restorative materials and treatments. Although conventional glass-ionomer cements (GICs) have relatively poor mechanical and adhesive strengths, their satisfactory biological features, ease of use, and low costs are distinct advantages. Most of the published reports of the clinical performance of the newer, high-strength esthetic conventional GICs specifically marketed for the ART approach have been from short-term studies. Satisfactory clinical performance has been demonstrated for single-surface posterior restorations only, over three years. Findings indicate that further improvements in restorative materials are still required for their use with the ART approach, together with further clinical investigations of the remineralization of shallow open caries lesions, as an alternative to placing definitive restorations.

Clinical performance of resin-modified glass ionomer cement restorations in primary teeth. A retrospective evaluation

BACKGROUND

The authors retrospectively evaluated the clinical performance of one resin-modified glass ionomer cement as a restorative material in Class I, Class II, Class III and Class V restorations in primary teeth.

METHODS

A total of 306 patients who had received a total of 864 resin-modified glass ionomer restorations, which had been in their mouths for a minimum of three years, were included in this evaluation. The authors assessed the clinical observations recorded in patients' records and used bitewing radiographs to assess Class II restorations.

RESULTS

The authors found an overall restoration success rate of 93.0 percent, with Class I restorations having a 92.6 percent success rate, Class II restorations having a 93.3 percent success rate, Class III restorations having a 100 percent success rate, and Class V restorations having a 98.0 percent success rate.

CONCLUSIONS

The resin-modified glass ionomer cement functioned well as a Class I, Class II, Class III and Class V restorative material in primary teeth.

CLINICAL IMPLICATIONS

Resin-modified glass ionomer restorative cement is a durable and reliable material to use for Class I, Class II, Class III and Class V restorations in primary teeth. Therefore, dentists have a proven alternative to silver amalgam and resin-based composite for primary tooth restoration.

Mineralization in bovine dentin adjacent to glass-ionomer restorations

OBJECTIVES

To assess the uptake of fluoride as well as the increase in mineralization by bovine dentin after restoring an experimentally made cavity with conventional glass-ionomer cement or a polyacid resin composite.

METHODS

Cylindrical cavities were prepared on the labial root surfaces in bovine dentin. The cavities were restored with the test material. The restored teeth were individually suspended in distilled water at 37 degrees C for 30 days. The teeth were sectioned and the superficial dentin cavity walls were analyzed for fluoride, calcium, and phosphorus by an EPMA device. The effects of the different fluoride-releasing materials on the hardness of the dentin were determined by indentation (20-microm intervals below the filled surface into the underlying sound dentin from the surface to a depth of 100microm).

RESULTS

Conventional glass-ionomer cement had a significant effect on fluoride uptake. In addition, the calcium and phosphorus scan revealed the elevation of calcium and phosphorus levels in a deeper zone corresponding to the locations of the fluoride uptake at the surface of axial wall. However, the polyacid resin composite did not exhibit a zone of calcium and phosphorus elevation. The average dentin hardness under conventional glass-ionomer cement in the studied five distances ranged from 84.3 to 61.3KHN, however, that of the polyacid resin composite ranged from 62.5 to 64.9KHN. Analysis of variance for these data demonstrated a significant difference in hardness between the 20-microm depth and the other depths (P<0.01, ANOVA Fisher's PSLD).

CONCLUSION

The present paper indicates that the fluoride penetrated deeper into the dentin with conventional glass-ionomer cement than the polyacid resin composite. Conventional glass-ionomer cement had a significant effect on fluoride uptake. In addition, hypermineralization occurred within the superficial dentin cavity wall region of conventional glass-ionomer cement.

Inhibition of bacterial and glucan adherence to various light-cured fluoride-releasing restorative materials

OBJECTIVES

This study investigated the potential plaque adhesion properties of various light-cured fluoride-releasing restorative materials by measuring the amount of adhering radiolabeled bacteria and glucan.

METHODS

Three resin-modified glass ionomer cements (RMGI) and two polyacid-modified resin composites (compomer) were used in this study. As a control, one light-cured resin composite was added. Disk-shaped specimens were made following the manufacturers' recommendations and the respective surfaces were finished with a 600-grit abrasive paper. Streptococcus sobrinus B13 was selected as a cariogenic bacterial strain. The amount of bacteria and glucan adhered to these specimens were measured after 3, 8 and 24h incubations with radiolabeled cariogenic bacteria and sucrose.

RESULTS

After 3 and 8h incubations, the amount of adhered bacteria and glucan was small and there were no significant differences among the restorative materials except in the resin composite. Although after 24h incubation the amounts of adhered bacteria and glucan, significantly increased on the RMGIs and compomers, these were still significantly less than the resin composite except one compomer. Although at 3h no good correlation was found between the contact angles and the amount of bacteria and glucans, the correlation coefficients were high at 8 or 24h. In addition, the coefficients for bacteria were always higher than those for glucan irrespective of the incubation times.

CONCLUSIONS

After 24h resin-modified glass ionomer cements and compomers showed significantly smaller amounts of adhered bacteria and glucans compared to resin composite with an exception of glucan adherence on one compomer.