Scientific Studies - Effectiveness of Glass Ionomers on Adjacent Teeth

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1 B&D Dental Technologies Inc. (May 201 4) Introducing SmartCrown Restorations Technic cle Scientific Studies - Effectiveness of Glass Ionomers on Adjacent Teeth 0.5 mm 1.0 mm 0.5 mm 1.0 mm 0.5 mm 1.0 mm 0.5 mm ZSG RLC RLP 50 Tooth 5 Z Tooth 5 RelyX 50 Tooth 5 RelyX Plus % Mineral content mm mm Distance (microns) % Mineral content mm 1.0 mm Distance (microns) % Mineral content mm 1.0 mm Distance (microns) Microradiographic images (50x) and corresponding mineral profiles of three specimens cut from the same tooth. Mineral profiles were determined at 0.5 and 1.0 mm from the material margin S. Presidents Dr., Ste. E, West Valley City, UT TEL FAX

2 Review Article Fluoride release and dentin caries inhibition adjacent to resin-modified glass-ionomer luting cements DARANEE TANTBIROJN 1 AFSHIN FALSAFI 2 SUMITA B. MITRA 2 RALPH DELONG 1 WILLIAM H. DOUGLAS 1 TIFFANY TON 2 1 Minnesota Dental Research Center for Biomaterials and Biomechanics, University of Minnesota, Minneapolis, USA. 2 3M ESPE Dental Products, St. Paul, USA. The objectives of this investigation were to compare the fluoride release and caries inhibition ability of resin-modified glass ionomer (RMGI) luting cements. Methods: Materials used for dentin caries inhibition were 3M ESPE RelyX TM Luting Plus Cement (RLP) paste-paste RMGI, RelyX TM Luting Cement (RLC) powder-liquid RMGI and Filtek TM Z250 composite/ Adper TM Single Bond adhesive (ZSB). Rectangular slots (6 2 1 mm) were prepared in 24 dentin blocks cut from 8 bovine roots, and filled with ZSB, RLC, and RLP. The specimens were immersed in 10 ml acetic acid solution ph 5.0 (37ºC, 3 wks) to create artificial dentin lesion, then sectioned into 400 µm slices and subjected to microradiography. Mineral loss ( Z) was calculated from mineral profiles at 0.5 and 1.0 mm from the material margin, and statistically analyzed (ANOVA, Fisher s, p<0.05). Fluoride release from cured cement discs (20 1 mm; n=8) in distilled water was measured after 1, 7, 14, 28, 90, 180, and 365 day using F-specific electrode and TISAB buffer. A conventional GIC, Ketac TM Cem, was used as a control for this experiment. Results: Z250 is not fluoridated and did not exhibit F release. The sustained F release from RLP and RLC were comparable to each other and higher than from the control conventional GIC. Both RMGIs showed pronounced inhibition zones in dentin adjacent to cement margin. Z values at 0.5 mm and 1.0 mm from RLP and RLC were significantly less compared to ZSB. Z values were not significantly different in RLP and RLC groups at 1.0 mm. Conclusion: Both the powder-liquid and paste-paste RMGIs, RelyX Luting and RelyX Luting Plus cements respectively, released comparable amounts of fluoride, and, in contrast to the composite, demonstrated inhibition zones at the adjacent dentin when subjected to in vitro demineralization. Both cements inhibited mineral loss in dentin compared to the composite up to 1.0 mm adjacent to the bonded interface. (Chin Dent J, 24(3): , 2005) Key words: caries inhibition, dentin demineralization, fluoride release, luting cement, resin-modified glass-ionomer. Restoration failure and replacement is an unresolved problem in dental practice 1. The main reason for such failure is secondary caries, which has been reported to be responsible for 40 to 60% of restoration replacements 1-4. Although risk factors for primary and secondary caries are well known Received: June 21, 2005 Accepted: August 7, 2005 Reprint requests to: Dr. Sumita B. Mitra, 260-2B-13, 3M, Center, St. Paul, MN , USA. theoretically, patient compliance and host factors can hinder the accurate prediction of restoration failure. Fluoride-releasing materials are indispensable tool to lower the risk of caries development 2. Among the vast array of restorative materials available at present, glass ionomer cements (GICs) are the greatest source of fluoride available to the surrounding tooth structures 5,6. Studies have shown that glass ionomers inhibit demineralization of the surrounding tooth structures in vitro 7-10, in situ 11,12, and provide protection against recurrent caries under clinical condition for patients with high caries risk Chin Dent J 2005 Vol 24 No 3 127

3 D. Tantbirojn, A. Falsafi, S.B. Mitra, et al. This can be attributed to the ability of glass ionomer cements to inhibit demineralization and enhance remineralization through release of fluoride to the adjacent tissue and surrounding fluid. Resin-modified glass ionomer (RMGI), were developed to provide the advantages of preferred handling and setting characteristics, while maintaining the sustained fluoride release behavior and good clinical adhesion of conventional GICs 5. Standard RMGIs are usually dispensed in a powderliquid form. To further improve the handling characteristics, paste-paste delivery system has been introduced. One recent paste-paste RMGI system is the RelyX Luting Plus system (3M ESPE, St Paul, MN) delivered through a convenient metered double-barreled dispenser called the clicker. The unique clicker delivery not only provides easy dispensing and easy mixing, but the consistent dosing should facilitate the material to achieve its optimal properties. One of the applications of GICs is as a luting cement in fixed prosthodontics 2,17. Apart from the capability of releasing fluoride to protect against secondary caries, RMGI luting cements have advantage over other types of cement in that it can adhere to tooth structures without the need for separate etching or conditioning steps. The selfadhesive property leads to minimal microleakage, and thus diminishes post-operative sensitivity. The manipulative procedure is fast and simple, also due to less concern for isolation, moisture control and anesthesia. In addition, GI luting cements exhibit good mechanical properties, low setting stress, and have evidence to strengthen core ceramics 17. While there have been several reports on the caries inhibitory property of GIC and RMGI restoratives there are hardly any published studies on similar efficacy of luting cements. The first objective of this study was to compare the fluoride release of the paste-paste RMGI luting cement with powder-liquid RMGI and conventional GIC. The second objective was to compare in vitro caries inhibition ability of these RMGI luting cements to a composite/adhesive system. MATERIALS AND METHODS Fluoride release Materials used in the fluoride release experiment are shown in Table 1. Three disk-shape specimens (20 mm in diameter and 1.0 mm in thickness) were prepared from each material using a Plexiglas split mold. The specimens were allowed to mature in a 95%-relaltive-humidity chamber for 1 h at 37 C before being removed from the mold and weighed on an analytical balance. Each specimen was immersed separately in 25 ml deionized water at 37 C. A fluoride ion-selective electrode (Orion model , Orion) was used to quantify the amount of fluoride ion released from each specimen into the deionized water. The electrode was calibrated with fluoride standards and the ionic strength was controlled by TISAB buffer. Fluoride released, calculated as µg F/g of specimen, was measured after 1, 7, 14, 28, 90, 180, and 365 days as shown in Figure 1. Table 1. Materials used in the study Material Product name Manufacturer Lot number Composition Conventional powder-liquid GI Powder-liquid RMGI luting cement Paste-paste RMGI luting cement Ketac Cem (KC) 3M ESPE Powder: FAS glass Liquid: polyalkenoic acid, water, tartaric acid RelyX TM Luting Cement (RLC) RelyX TM Luting Plus Cement (RLP) 3M ESPE Powder: FAS glass, opacifier, redox catalysts Liquid: Methacrylated polyalkenoic acid, HEMA, water, tartaric acid, stabilizers 3M ESPE A6805 B6802 Paste A: FAS glass, water, HEMA, redox catalyst, opacifier Paste B: Methacrylated polyalkenoic acid, water, HEMA, Restorative composite Z250 3M ESPE 3WR Zr/Si Filler, BisGMA, TEGDMA, BisEMA6, UDMA, photoinitiator system Dentin adhesive Adper Single Bond 3M ESPE 7AT (etching gel); 0TP (adhesive) Etching gel: phosphoric acid, water, fumed silica, colorant Adhesive: Methacrylated polyalkenoic acid, water, ethanol, HEMA, BisGMA, UDMA, GDMA, photoinitiator system 128 Chin Dent J 2005 Vol 24 No 3

4 Dentin caries inhibition of glass-ionomer Cumulative F-Release (micro gf/g) days RelyX Luting Plus RelyX Luting Ketac Cem Figure 1. Cumulative fluoride release from various glass ionomer cements plotted against observation periods up to 1 year. Dentin demineralization 24 dentin blocks were cut from eight roots of extracted bovine incisors (Figure 2A). Rectangle slots (6 2 1 mm) were prepared in each dentin specimen using #56 carbide bur in high-speed hand piece with copious amount of water. The slots (n=8) were filled with Filtek TM Z250 composite with Adper TM Single Bond adhesive (ZSB), RelyX TM Luting Cement (RLC) powder-liquid RMGI, or RelyX TM Luting Plus Cement (RLP) paste-paste RMGI, and finished with Soflex TM discs (3M ESPE, St Paul, MN). Material information is shown in Table 1. The specimens were coated all around with acid-resistant nail varnish except the material and adjacent dentin as shown in Figure 2B. Artificial caries lesions were created by immersing the specimen in 10 ml of demineralizing solution at 37 C. The demineralizing solution, modified from Mukai et. al. 18, contained 50 mm acetic acid, 1.5 mm CaCl 2, 0.9 mm KH 2PO 4, 0.1 ppm F. The ph was adjusted to 5.0 with 1 M KOH. After three weeks, the specimens were removed from the demineralizing solution, rinsed with distilled water, embedded in acrylic resin and cut into thin slices (Figure 2C) using a diamond blade (Isomet TM Low Speed Saw, Buehler, Lake Bluff, IL) with water coolant. Each specimen yielded 3 to 6 dentin slices with approximate thickness of 500 µm. The dentin slices were ground by hand on wet 600 grit SiC paper (Buehler) to achieve a thickness of approximately 400 µm. Figure 2D is the diagram of the specimen ready for microradiography, showing orientation of the restored cavity and the demineralized lesion on adjacent dentin. The specimens along with an aluminum step wedge were arranged between moist filter paper (Whatman, W&R Balston Limited, UK) to prevent dehydration. Microradiograph was obtained with a Picker Hotshot X-ray machine (Picker Industrial Products, Cleveland, OH) operating at 12 kv and 1 ma for the exposure time of 54 s, using Ultra-speed Dental Films (Kodak DF-58, Eastman Kodak Company, Rochester, NY). The image of the microradiograph was captured Figure 2. Specimen preparation. A. Three dentin blocks were cut from bovine root. B. Specimen was filled and coated with nail polish. C. Thin slices were cut from each specimen. D. Orientation of the restored cavity and demineralized lesion on adjacent dentin. Chin Dent J 2005 Vol 24 No 3 129

5 D. Tantbirojn, A. Falsafi, S.B. Mitra, et al. Table 2. Cumulative fluoride release in µg F/g material (mean + SD) from restorative composite Z250, RelyX Luting Cement (RLC), and RelyX TM Luting Plus Cement (RLP) and Ketac Cem (KC) after 1, 7, 14, 28, 90, 180, and 365 days Material Days Z250 RLC RLP KC ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 350 at 100x magnification under a stereomicroscope (Olympus SZH10, Japan) with CCD camera (Sony DXC-151A, Japan). The light intensity was standardized by adjusting the light source so that an unexposed X-ray film reached a particular luminance value, which allowed a constant light incident. Microdensitometry was carried out using an image analysis software Optimas TM 5.2 (Optimas TM Corporation, Edmonds, WA). The line luminance function in the software provides a gray scale profile across the area of 0.25 mm width. Each line was scanned from lesion surface to underlying sound dentin (0.5 mm length). Two measurements were done at 0.5 and 1 mm adjacent to the material. Mineral content (volume % mineral) was calculated from the gray value (radiopacity) of the microradiograph calibrated with the aluminum step wedge A mineral profile was constructed from the mineral content as a function of distance from the lesion surface to the underlying sound dentin. Amount of mineral loss or Z (volume % mineral-µm) is the integration of the area between the mineral profile of the lesion and the average volume % mineral that is extrapolated from the underlying sound dentin. Custom software was written to calculate Z from each mineral profile by defining the underlying sound dentin to contain 45 volume % mineral as an internal standard. Zs at 0.5 and 1 mm from the material margin were compared between the three materials using a one-way ANOVA followed by Fisher s test at a significant level of Fluoride release RESULTS The cumulative amount of fluoride release from Z250, the two RMGIs, and the conventional GIC control KC at 1, 7, 14, 28, 90, 180, and 365 days was plotted vs time in Figure 1 and presented in Table 2. Figure 1 shows the amount of cumulative fluoride release from various glass ionomer cements plotted against observation periods up to 1 year. Z250 is not fluoridated and did not liberate fluoride. Both the new paste-paste RMGI, RLP, and the earlier version powder-liquid RMGI, RLC, released comparable amounts of fluoride that are considerably higher than from the conventional GIC Ketac Cem. Dentin demineralization The subsurface lesion developed on dentin surface next to the material is seen as a dark (radiolucent) area covered by a radiopaque layer. Figure 3 depicts microradiographic images and corresponding mineral profiles of three specimens cut from the same tooth. Dentin lesion adjacent to restorative composite (ZSB) was extensive with very thin surface layer. A wedge-shape area is observed in close proximity to the composite in some cases. In the two glass ionomer groups (RLC and RLP), the lesions were not as deep as in the composite group. The surface layer of the lesions adjacent to RLC and RLP was thick and well-defined. In addition, pronounced inhibition zones where dentin caries could not develop was detected in close proximity to 130 Chin Dent J 2005 Vol 24 No 3

6 Dentin caries inhibition of glass-ionomer 0.5 mm 1.0 mm 0.5 mm 1.0 mm 0.5 mm 1.0 mm 0.5 mm ZSG RLC RLP 50 Tooth 5 Z Tooth 5 RelyX 50 Tooth 5 RelyX Plus % Mineral content mm mm Distance (microns) % Mineral content mm 1.0 mm Distance (microns) % Mineral content mm 1.0 mm Distance (microns) Figure 3. Microradiographic images (50x) and corresponding mineral profiles of three specimens cut from the same tooth. Mineral profiles were determined at 0.5 and 1.0 mm from the material margin. the cement-dentin interface. In the corresponding mineral profiles at 0.5 and 1.0 mm from the cavity margin, the faint radiopaque surface layer in ZSB group is seen as a small peak followed by the low mineral content body of the lesion, then the profile gradually rises to approach sound dentin. The well-developed surface layer in the RMGI groups is evidence by a large peak in the mineral profiles. The mineral profiles also show that lesions at 1.0 mm are deeper than lesions at 0.5 mm. The amount of mineral loss (DeltaZ) at 0.5 and Table 3. The amount of mineral loss (DeltaZ; Mean ± SD) at 0.5 and 1.0 mm from the margin of materials, Filtek TM Z250/Adper TM Single Bond adhesive (ZSB), RelyX TM Luting Cement (RLC), and RelyX TM Luting Plus Cement (RLP) Materials DeltaZ (VPM-µm) 0.5 mm 1.0 mm ZSB 7641 ± 621 a 7395 ± 573 a RLC 4267 ± 1322 b 5114 ± 1094 b RLP 5435 ± 430 c 5863 ± 623 b Same letter denotes mean values that are not significantly different for each distance (ANOVA, Fisher s, p>0.05). 1.0 mm from the material margin is shown in Table 3. Significant differences in mineral loss were found among all three materials at 0.5 mm distance (ANOVA and Fisher s test, p < 0.05). At 1 mm from the cement margin, the differences between RLP and RLC were not significant (ANOVA and Fisher s test p > 0.05). In other words, both glass ionomer cements showed higher caries inhibitory effect than composite at 1 mm periphery of the material. DISCUSSION In the present study, microradiography has been modified from a standard methodology by using a periapical X-ray film instead of a holographic film. The relatively coarse grain of the periapical film was compensated by averaging the radiopacity across an area of 0.25 mm, i.e., the mineral profile at 0.5 mm represents the measurement from to mm. Low energy x-ray (12 kv) was used in order to permit high absorption by the specimen, thus regions with slight differences in mineral content would be distinguishable 19. The average mineral content of Chin Dent J 2005 Vol 24 No 3 131

7 D. Tantbirojn, A. Falsafi, S.B. Mitra, et al. sound dentin computed by this method was vol % 22 which is comparable with the established value of 47 % 23. Considering high prevalence of restoration failure and replacement with secondary caries as a main cause, restorative material with anticariogenic potential is crucial in dental armamentarium. Glass ionomer cements have shown the anticariogenic properties in several in situ and clinical studies 11,15,16, 24. In a cross-over in situ study, both conventional and resin-modified glass ionomers were able to reduce enamel demineralization under a severe cariogenic challenge where the enamel blocks were dipped in sucrose solution extraorally 8 times a day and the subjects used non-fluoridated dentifrice 24. Another in situ study also showed less demineralization of enamel adjacent to resin-modified glass ionomer restorative materials than composite group in an interproximal crown model after 4 weeks without fluoride dentifrice 11. The anticariogenic effect of glass ionomers is remarkably crucial in high-risk patients. Recurrent caries reductions around cervical restorations for conventional and resin-modified glass ionomers relative to composite were greater than 80% in xerostomic patients with less compliance to fluoride supplementation 15. Similarly, less caries developed at margins of glass ionomer restorations compared with amalgam after 2 years in xerostomic patients who did not routinely use topical fluoride 16. The ability to release fluoride over a prolonged period of time and improve resistance against secondary caries in coronal and root surfaces make glass ionomers a good candidate as luting agent in fixed prosthodontics 12, 17. In the present study, the new paste-paste RMGI luting cement (RLP) exhibited similar sustained fluoride release as its precursor powder/liquid material (RLC). The total level of fluoride release from both RMGIs was higher than from a classical conventional GIC. Glass ionomer luting cements like the ones present here, which have shown potential to intervene with the development of dentin caries, can be viewed as therapeutic material conforms to the emerging concept of minimally invasive dentistry 25. CONCLUSION In conclusion, RelyX Luting and RelyX Luting Plus cements released comparable amounts of fluoride. The fluoride release was greater than that of conventional GICs studied. When subjected to in vitro demineralization, both luting cements demonstrated inhibition zones adjacent to the cavity margin in contrast to the composite. RelyX and RelyX Plus luting cements showed lower mineral loss in dentin compared to the composite up to 1 mm adjacent to the bonded interface. Clinically these RMGI luting cements may help inhibit the development of caries in the cement proximity. This is especially beneficial for compromised marginal areas that are under cariogenic risks. REFERENCES 1. Fontana M, Gonzalez-Cabezas C. Secondary caries and restoration replacement: an unresolved problem. Compend Contin Educ Dent, 21: 15-30, Hicks J, Garcia-Godoy F, Donly K, Flaitz C. Fluoridereleasing restorative materials and secondary caries. Dent Clin North Am, 46: , Neville BW, Damm DD, Allen CM, Bouquot JE. Bone pathology. In Oral & Maxillofacial Pathology 2nd ed, Neville BW et al eds, W.B. Saunders, Philadelphia, pp , Wilson NH, Burke FJ, Mjor IA. Reasons for placement and replacement of restorations of direct restorative materials by a selected group of practitioners in the United Kingdom. Quintessence Int, 28: , Mitra SB. In vitro fluoride release from a light-cured glass-ionomer liner/base. J Dent Res, 70: 75-78, Suljak JP, Hatibovic-Kofman S. A fluoride releaseadsorption-release system applied to fluoride-releasing restorative materials. Quintessence Int, 27: , Tantbirojn D, Douglas WH, Versluis A. Inhibitive effect of a resin-modified glass ionomer cement on remote enamel artificial caries. Caries Res, 31: , Torii Y, Itota T, Okamoto M, Nakabo S, Nagamine M, Inoue K. Inhibition of artificial secondary caries in root by fluoride-releasing restorative materials. Oper Dent, 26: 36-43, Forss H, Seppa L. Prevention of enamel demineralization adjacent to glass ionomer filling materials. Scand J Dent Res, 98: , Hicks MJ, Flaitz CM, Silverstone LM. Secondary caries formation in vitro around glass ionomer restorations. Quintessence Int, 17: , Donly KJ, Segura A, Wefel JS, Hogan MM. Evaluating the effects of fluoride-releasing dental materials on adjacent interproximal caries. J Am Dent Assoc, 130: , ten Cate JM, van Duinen RN. Hypermineralization of dentinal lesions adjacent to glass-ionomer cement restorations. J Dent Res, 74: , Donly KJ, Segura A, Kanellis M, Erickson RL. Clinical performance and caries inhibition of resin-modified glass 132 Chin Dent J 2005 Vol 24 No 3

8 Am J Dent Apr;21(2): Long-term evaluation of the remineralization of interproximal carieslike lesions adjacent to glass-ionomer restorations: a micro-ct study. Lee HS 1, Berg JH, García-Godoy F, Jang KT. Author information 1 Dental Research Institute and Department of Pediatric Dentistry, College of Dentistry, Seoul National University, Seoul, Korea. Abstract PURPOSE: To compare the remineralization of incipient artificial interproximal caries in the presence of three glassionomer cements (highly-filled glass-ionomer cement, compomer, resin-modified glass-ionomer cement) and a resin composite (control). METHODS: Proximal restorations were simulated by placing tooth specimens and the various glass-ionomer cements in closed containers with artificial saliva at 37 degrees C and ph 7.0 for 30 days with constant circulation. Tomographic images were obtained with a micro CT scanner at 90, 180, and 270 days, and densitymeasuring software was used to calculate the micro-density of artificial caries lesions in the specimens. The mean density changes were compared between groups in order to evaluate the effects of remineralization. All data were analyzed using one-way ANOVA and the post-hoc Tukey multiple comparison test at P < RESULTS: While the density of artificial caries lesions increased for all treatments, the increases for the three glass-ionomer groups were significantly higher than that for the resin group in each 3-month period. As time increased, the amount of density also increased for the glass-ionomer groups, and significant differences were found between the remineralization effects of the glass-ionomer groups. The micro CT proved to be an effective evaluation method.

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10 International Dental Journal Volume 60, Issue 3, June 2010, Pages Fluorides leaching from restorative materials and the effect on adjacent teeth. Qvist, V. a, Poulsen, A. b, Teglers, P.T. c, Mjör, I.A. d a Department of Cariology and Endodontics, School of Dentistry, University of Copenhagen, Copenhagen, Denmark b Public Dental Health Service, Hillerød Municipality School of Oral Health Care, University of Copenhagen, Copenhagen, Denmark Abstract OBJECTIVE: Placing a Class II restoration in a tooth changes the local environment, including that for the adjacent tooth. Apart from the change to a less- or non-cariogenic environment for the restored tooth, the effect of leachable components from a restoration in the adjacent tooth should be taken into consideration. METHOD: Practice-based clinical studies comprising of 1341 unrestored proximal surfaces in contact with Class II restorations using different restorative materials were reviewed to assess the effect on the caries development on the adjacent teeth. The caries status of the adjacent un-restored proximal surface was assessed as being clinically sound, having active caries with or without cavitation, or having arrested caries. Restorations from nine clinicians were reviewed. They had attended annual meetings where all aspects of the investigation had been discussed. The surfaces were followed for up to eight years. RESULTS: A reduced rate of caries development and progression were found on surfaces in contact with fluoride releasing materials like glass ionomers, resin modified glass ionomers and compomers compared to surfaces in contact with amalgam. CONCLUSION: Fluoride releasing materials reduce the development and progression of primary caries on adjacent proximal surfaces.

11 The need for restorative caries treatment of adjacent surfaces in contact with different restorative materials is illustrated by the survival distributions in Figure 1. Survival in the present context means without the need for restorative treatment. Surfaces in contact with AM showed a greater need for restorative treatment compared to all other materials (p<0.002), while the differences among surfaces adjacent to GI, RMGI and COM were not statistically significant (p>0.05). The 75% survival time, i.e., the time prior to the need for restoration of 25% of the adjacent surfaces, was estimated to be 1.8 years for surfaces adjacent to AM vs. 2.6 years for GI and 2.5 years for RMGI and COM surfaces (Fig. 1). The median time prior to the need for restoration of 50% of the adjacent proximal surface was 3.6 years for AM, 4.4 years for COM, and 5.7 years for RMGI. Source: International Dental Journal Volume 60, Issue 3, June 2010, Pages Fluorides leaching from restorative materials and the effect on adjacent teeth. Qvist, V. a, Poulsen, A. b, Teglers, P.T. c, Mjör, I.A. d

12 J Dent Sep;34(8): Epub 2006 Mar 15. Chemical exchange between glass-ionomer restorations and residual carious dentine in permanent molars: an in vivo study. Ngo HC 1, Mount G, Mc Intyre J, Tuisuva J, Von Doussa RJ. Author information 1 Dental School, University of Adelaide, Adelaide, Australia. hien.ngo@adelaide.edu.au Abstract OBJECTIVE: To evaluate the remineralization of carious dentine following the restoration of an extensive lesion in a permanent molar with a high strength glass-ionomer cement (GIC). MATERIALS AND METHODS: Thirteen first permanent molars, which were scheduled for extraction because of the presence of extensive caries lesions, were selected for this study. They were first restored, according to the ART technique, using encapsulated Fuji IX(GP), which contains a strontium glass rather than the traditional calcium glass. The cavities were prepared with a clean enamel margin and minimal removal of the carious dentine around the walls. After a period of 1-3 months they were harvested and subsequently sectioned and examined using an electron probe microanalysis (EPMA) and scanning electron microscopy (SEM). RESULTS: EPMA demonstrated that both fluorine and strontium ions had penetrated deep into the underlying demineralized dentine. The only possible source of these ions was the GIC restoration. CONCLUSION: The pattern of penetration of the fluorine and strontium ions into the dentine was consistent with a remineralization process.

13 USAF Dental Evaluation & Consultation Service Glass-Ionomer Materials are still a piece of the clinical treatment puzzle... (11/06) Ngo HC, Mount G, Mc Intyre J, Tuisuva J, Von Doussa RJ. Chemical exchange between glassionomer restorations and residual carious dentine in permanent molars: An in vivo study. Journal of Dentistry 2006;34: Clinicians strive to remove all carious dentin, both infected and affected, during restorative procedures. Even so, some affected dentin may remain even after the best attempts. Due to the release of fluoride, glass-ionomer materials used as liners, bases, and restorative materials to assist in the remineralization of remaining carious dentin has been suggested. The purpose of this in vivo study was to evaluate carious dentin changes following the restoration of grossly carious permanent first molar teeth using a high-strength glass-ionomer restorative material. Thirteen first permanent molars, which were scheduled for extraction because of the presence of extensive caries, were selected for this study. Both infected and affected dentin was removed following the principles of the Atraumatic Restorative Treatment (ART) technique in which all infected carious dentin is removed, but some affected carious dentin may remain. After ensuring the presence of non carious peripheral enamel margins, the preparations were restored using encapsulated Fuji IXGP, which is based on a strontium glass material rather than the traditional calcium glass. After a period of 1-3 months the teeth were extracted, sectioned, and examined using an electron probe microanalysis (EPMA) and scanning electron microscopy (SEM). The results of the ultrastructural evaluation demonstrated that both fluorine and strontium ions had penetrated deep into the underlying demineralized dentine. The strontium ions were found to have penetrated the entire depth of the remaining carious dentin while fluoride ions traversed 94% of the carious dentin. The only possible source of these ions was from the glass ionomer cement restoration, and the findings were reported as consistent with a remineralization process. DECS Comment: The therapeutic effect of glass-ionomer materials has been richly suggested in the scientific literature, with many in vitro evaluations demonstrating either increased resistance to acid challenge or remineralization of dental tissues. Some clinical trials involving glass ionomer restorative materials have been positive, especially when used in special patient populations. However, clinical reports of glass-ionomer materials considered as a whole are equivocal, as a meta analysis of glass ionomer clinical trials has shown that a therapeutic benefit of these materials cannot be positively demonstrated. Needless of the ongoing debates, this in vivo study is unique in that the restorative material chosen is based on a strontium glass material, instead of the usual calcium-based materials that are commonly used. Any presence of strontium and fluoride found in the carious and/or remineralized dentin undoubtedly would be from the glass-ionomer restorative. Although not specifically mentioned, it should also be considered that all of the molars restored had mature apices, as the ages of the patients ranged from years of age. Therefore, the results can also be positively tempered that any remineralization process would be independent of any reparative potential suggested with teeth possessing open apices. This study is strongly suggestive of the therapeutic benefit of glass ionomer restorative materials.

14 Source: J Dent Sep;34(8): Epub 2006 Mar 15. Chemical exchange between glass-ionomer restorations and residual carious dentine in permanent molars: an in vivo study. Ngo HC 1, Mount G, Mc Intyre J, Tuisuva J, Von Doussa RJ.

15 Source: J Dent Sep;34(8): Epub 2006 Mar 15. Chemical exchange between glass-ionomer restorations and residual carious dentine in permanent molars: an in vivo study. Ngo HC 1, Mount G, Mc Intyre J, Tuisuva J, Von Doussa RJ.

16 ISRN Dentistry Volume 2013 (2013), Article ID , 8 pages 1 Faculty of Dentistry, The University of Sydney, Australia 2 Westmead Oral Health Centre, Level 1, Faculty Office, Westmead Hospital, Darcy Road, Westmead, Sydney, NSW 2145, Australia 3 Faculty of Dentistry, Tanta University, Egypt Abstract Aim. The aim of the study was to determine whether three fluoride containing resin composites could maintain fluoride release, fluoride recharge, and mechanical stability over long-term (18-month) aging. Materials and Methods. Fluoride containing composites Beautifil II, Gradia Direct X, Tetric EvoCeram, and glass ionomer Fuji IX Extra were analyzed. Specimens of each material were fabricated for two test groups: Group 1: bimonthly fluoride release/recharge analysis (n=5); Group 2: hardness and elastic modulus analysis (n=6). Nanoindentation was employed at 24 hours and at 1, 3, 6, 12, and 18 months. After 18 months, each specimen was immersed (recharged) in 5000 ppm NaF gel, and fluoride rerelease, hardness, and elastic modulus were measured. Results. Beautifil II and Gradia Direct X maintained fluoride release and recharge capability throughout 18-month aging (Beautifil II > Gradia Direct X > Tetric EvoCeram). The fluoride rerelease from Beautifil II following a 10-minute NaF recharge (at 18 months) was comparable to the long-term fluoride release from Fuji IX Extra. Elastic modulus and hardness did not change significantly (P>0.05) with fluoride release, recharge, and water aging over 18 months for all three analyzed composites. Conclusions. The long-term fluoride release, fluoride recharge, and mechanical property stability of Beautifil II and Gradia Direct X render these composites suitable for load bearing restorations in high caries risk patients. Clinical Relevance. The ability for Beautifil II and Gradia Direct X to maintain fluoride release and fluoride recharge capability, despite long-term aging, raises the potential for unrestored tooth surfaces in contact with Beautifil II or Gradia Direct X restorations to demonstrate a reduced rate of caries incidence compared to unrestored surfaces adjacent to conventional nonfluoride containing composites.

17 Source: ISRN Dentistry Volume 2013 (2013), Article ID , 8 pages Long-Term Fluoride Exchanges at Restoration Surfaces and Effects on Surface Mechanical Properties Steven Naoum, 1,2 Elizabeth Martin, 1,2 and Ayman Ellakwa 1,2,3

18 Focus on Fluorides: Update on the Use of Fluoride for the Prevention of Dental Caries Clifton M. Carey, BA, MS, PhD Abstract Improving the efficacy of fluoride therapies reduces dental caries and lowers fluoride exposure. Background Fluoride is delivered to the teeth systemically or topically to aid in the prevention of dental caries. Systemic fluoride from ingested sources is in blood serum and can be deposited only in teeth that are forming in children. Topical fluoride is from sources such as community water, processed foods, beverages, toothpastes, mouthrinses, gels, foams, and varnishes. The United States Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA) have proposed changes in their long standing recommendations for the amount of fluoride in community drinking water in response to concerns about an increasing incidence of dental fluorosis in children. Current research is focused on the development of strategies to improve fluoride efficacy. The purpose of this update is to inform the reader about new research and policies related to the use of fluoride for the prevention of dental caries. Methods Reviews of the current research and recent evidence based systematic reviews on the topics of fluoride are presented. Topics discussed include: updates on community water fluoridation research and policies; available fluoride in dentifrices; fluoride varnish compositions, use, and recommendations; and other fluoride containing dental products. This update provides insights into current research and discusses proposed policy changes for the use of fluoride for the prevention of dental caries. Conclusions The dental profession is adjusting their recommendations for fluoride use based on current observations of the halo effect and subsequent outcomes. The research community is focused on improving the efficacy of fluoride therapies thus reducing dental caries and lowering the amount of fluoride required for efficacy.

19 Source: Focus on Fluorides: Update on the Use of Fluoride for the Prevention of Dental Caries Clifton M. Carey, BA, MS, PhD J Evid Base Dent Pract 2014:S1

20 Revista Odontológica Mexicana Vol. 18, No. 2 April-June 2014 pp Fluoride release of two glass-ionomer cements: in vitro study Carol Rubí Delgado Muñoz,* Juana Paulina Ramírez Ortega, Adolfo Yamamoto NaganoII ABSTRACT Objective: The aim of the present study was to compare the amount of fl uoride released by two glass-ionomer cements: Ketac Molar Easymix (3M ESPE), which has recently appeared in the market and offers the additionl advantage of easy mixing, and FUJI II (GC Dental Industrial Corporation), which has been for a longer time available in the market. Methods: Both materials were handled according to the manufacturer s instructions. 15 samples were made of each glass ionomer cement using sample molds which measured 4 mm diameter x 6 mm height. Glass ionomer cement was placed into the molds and then pressed. Samples were introduced in an oven (37 ± 1 oc at 90% relative humidity). After one hour had elapsed, samples were withdrawn from the oven and then individually immersed in 1 ml de-ionized water in a hermetically sealed plastic container, to be later stored in a chamber at 37 ± 1 C. After 24 hours, samples were removed from the chamber and withdrawn from the storing solution, they were then rinsed with deionized water and excess water was removed with blotting paper. Samples were then transferred to another container adding 1 ml deionized water in order to be placed in the oven under the same conditions. Total ionic strength adjustment buffer solution was incorporated into the storing solution for it to be read with the help of a potentiometer (ph-meter) and a fluoride selective electrode for fl uoride under magnetic agitation. Prior to conducting fl uoride measurements, solutions were prepared in different concentrations in order to establish the calibration curve. The same procedure was performed in the aforementioned manner during the 36 days which the study lasted. Results: Both cements released fl uoride. For both cements, highest release was observed during the fi rst 24 hours. Release declined during the second day and kept gradually decreasing with time. Results were statistically analyzed using the Mann-Whitney test. No statistically significant differences were observed. Conclusions: Both glass ionomer cements exhibited similar fl uoride release. Glass ionomer cement are ideal for use in preventive dentistry as well as in atraumatic restorative technique. * Graduate, Pedodontics Specialty. Professor, Dental Materials Department. II Professor, Pedodontics Specialty.

21 Source: Revista Odontológica Mexicana Vol. 18, No. 2 April-June 2014 pp Fluoride release of two glass-ionomer cements: in vitro study Carol Rubí Delgado Muñoz,* Juana Paulina Ramírez Ortega, Adolfo Yamamoto NaganoII

22 Hook et al. Journal of Nanobiotechnology 2014, 12:3 Development of a novel antimicrobial-releasing glass ionomer cement functionalized with chlorhexidine hexametaphosphate nanoparticles Edward R Hook1, Olivia J Owen1, Candice A Bellis1, James A Holder1,2, Dominic J O Sullivan1 and Michele E Barbour1* Abstract Background: Glass ionomer cements (GICs) are a class of dental biomaterials. They have a wide range of uses including permanent restorations (fillings), cavity linings, fissure sealants and adhesives. One of the most common reasons for replacing a dental restoration is recurrent bacterial tooth decay around the margins of the biomaterial. Therefore, a dental biomaterial which creates a sustained antimicrobial environment around the restoration would be of considerable clinical benefit. In this manuscript, the formulation of a GIC containing novel antimicrobial nanoparticles composed of chlorhexidine hexametaphosphate at 1, 2, 5, 10 and 20% powder substitution by mass is reported. The aim is to create GICs which contain chlorhexidine-hexametaphosphate nanoparticles and characterize the nanoparticle size, morphology and charge and the release of chlorhexidine and fluoride, tensile strength and morphology of the GICs. Results: The GICs released chlorhexidine, which is a broad spectrum antimicrobial agent effective against a wide range of oral bacteria, over the duration of the experiment in a dose-dependent manner. This was not at the expense of other properties; fluoride release was not significantly affected by the substitution of antimicrobial nanoparticles in most formulations and internal structure appeared unaffected up to and including 10% substitution. Diametral tensile strength decreased numerically with substitutions of 10 and 20% nanoparticles but this difference was not statistically significant. Conclusion: A series of GICs functionalized with chlorhexidine-hexametaphosphate nanoparticles were created for the first time. These released chlorhexidine in a dose-dependent manner. These GIC materials may find application in the development of a new generation of antimicrobial dental nanomaterials.

23 Source: Hook et al. Journal of Nanobiotechnology 2014, 12:3 Development of a novel antimicrobial-releasing glass ionomer cement functionalized with chlorhexidine hexametaphosphate nanoparticles Edward R Hook1, Olivia J Owen1, Candice A Bellis1, James A Holder1,2, Dominic J O Sullivan1 and Michele E Barbour1*

24 ISRN Dentistry Volume 2013 (2013), Article ID , 8 pages 1 Faculty of Dentistry, The University of Sydney, Australia 2 Westmead Oral Health Centre, Level 1, Faculty Office, Westmead Hospital, Darcy Road, Westmead, Sydney, NSW 2145, Australia 3 Faculty of Dentistry, Tanta University, Egypt Abstract Aim. The aim of the study was to determine whether three fluoride containing resin composites could maintain fluoride release, fluoride recharge, and mechanical stability over long-term (18-month) aging. Materials and Methods. Fluoride containing composites Beautifil II, Gradia Direct X, Tetric EvoCeram, and glass ionomer Fuji IX Extra were analyzed. Specimens of each material were fabricated for two test groups: Group 1: bimonthly fluoride release/recharge analysis (n=5); Group 2: hardness and elastic modulus analysis (n=6). Nanoindentation was employed at 24 hours and at 1, 3, 6, 12, and 18 months. After 18 months, each specimen was immersed (recharged) in 5000 ppm NaF gel, and fluoride rerelease, hardness, and elastic modulus were measured. Results. Beautifil II and Gradia Direct X maintained fluoride release and recharge capability throughout 18-month aging (Beautifil II > Gradia Direct X > Tetric EvoCeram). The fluoride rerelease from Beautifil II following a 10-minute NaF recharge (at 18 months) was comparable to the long-term fluoride release from Fuji IX Extra. Elastic modulus and hardness did not change significantly (P>0.05) with fluoride release, recharge, and water aging over 18 months for all three analyzed composites. Conclusions. The long-term fluoride release, fluoride recharge, and mechanical property stability of Beautifil II and Gradia Direct X render these composites suitable for load bearing restorations in high caries risk patients. Clinical Relevance. The ability for Beautifil II and Gradia Direct X to maintain fluoride release and fluoride recharge capability, despite long-term aging, raises the potential for unrestored tooth surfaces in contact with Beautifil II or Gradia Direct X restorations to demonstrate a reduced rate of caries incidence compared to unrestored surfaces adjacent to conventional nonfluoride containing composites.

25 Source: ISRN Dentistry Volume 2013 (2013), Article ID , 8 pages Long-Term Fluoride Exchanges at Restoration Surfaces and Effects on Surface Mechanical Properties Steven Naoum, 1,2 Elizabeth Martin, 1,2 and Ayman Ellakwa 1,2,3

26 Australian Dental Journal 2012; 57: The effect of repeated fluoride recharge and storage media on bond durability of fluoride rechargeable Giomer bonding agent S Naoum,* J O Regan,* A Ellakwa,* R Benkhart,* M Swain,* E Martin* *Faculty of Dentistry, The University of Sydney, New South Wales. Abstract Background: For a restorative material or adhesive to exhibit caries inhibitive potential through fluoride release, it must be capable of fluoride recharge. The aim of this study was to evaluate the effect of repeated fluoride recharge and different storage media on dentine bond strength durability. Methods: Two self-etch adhesive systems (two-step) were evaluated: fluoride-rechargeable Giomer FL- Bond II and nonfluoride-containing UniFil Bond. For each adhesive 32 human dentine specimens were prepared for shear bond strength testing. The specimens were randomly allocated to one of four storage groups: Group 1 24-hour water ageing; Group 2 four-month water ageing; Group 3 four-month water ageing with weekly fluoride recharge (5000 ppm for 10 minutes); and Group 4 four-month acid ageing with weekly fluoride recharge. Results: Weekly fluoride recharge over four months ageing did not significantly (p > 0.05) reduce the dentine shear bond strength of FL-Bond II or UniFil Bond. Storage media did not significantly (p > 0.05) affect bond durability. Conclusions: The adhesion between fluoride rechargeable FL-Bond II and dentine maintained durability despite regular fluoride recharge over the four months ageing. Clinicians prescribing the fluoride recharge regime used in the present study to reduce recurrent caries incidence associated with Giomer FL-Bond II restorations can do so without compromising dentine bond strengths.

27 Source: Australian Dental Journal 2012; 57: The effect of repeated fluoride recharge and storage media on bond durability of fluoride rechargeable Giomer bonding agent S Naoum,* J O Regan,* A Ellakwa,* R Benkhart,* M Swain,* E Martin* *Faculty of Dentistry, The University of Sydney, New South Wales.

28 International Dental Journal 2012; 62: Clinical applications of glass ionomers in endodontics: a review Zahed Mohammadi1,2 and Sousan Shalavi3 1Department of Endodontics, Hamedan University of Medical Sciences, Hamedan, Iran; 2Iranian Centre for Endodontic Research (ICER), Tehran, Iran; 3General Dental Practitioner, Hamedan, Iran. Abstract Glass ionomer cements (GICs) are biocompatible and have capacities to release fluoride and to bond to dentine, and thus are appropriate for use in endodontics. This paper reviews the composition and properties of different GICs, including their biocompatibility and antibacterial activity, their applications as intraorifice barriers and root canal sealers, and their use in the repair of root perforations, root-end fillings and temporary coronal restorations. ANTIMICROBIAL EFFECTS Heling and Chandler6 assessed four root canal sealers [Pulp Canal Sealer EWT (Kerr, Romulus, MI, USA), Sealapex (Sybron Endo, Orange County, CA, USA), AH-26 (Dentsply DeTrey, Konstanz, Germany), Ketac-Endo (ESPE GmbH & Co., Seefeld Oberbay, Germany)] for their antibacterial effects within dentinal tubules. Findings showed that all sealers exhibited antibacterial activity at 24 hours, except Ketac-Endo. The activity of Pulp Canal Sealer EWT was similar at 24 hours and 7 days. Sealapex had greater antibacterial effect at 7 days than it did at 24 hours. The strongest effects were demonstrated by AH-26. Shalhav et al.7 evaluated the antibacterial activities of Ketac-Endo and Roth s cement (Roth International Ltd., Chicago, IL, USA) using an agar diffusion test (ADT) and a direct contact test (DCT). The results showed that in the ADT, freshly mixed Ketac-Endo exhibited a two-fold greater inhibition zone than Roth s cement, whereas in the DCT, both freshly mixed Ketac-Endo and Roth s cement completely inhibited bacterial growth. The 24-hour and 7-day samples of Ketac- Endo showed no antibacterial activity, whereas Roth s cement continued to exhibit a strong effect at those time-points. Lai et al.8 evaluated the antibacterial effects of three resinous rootend filling materials [Fuji II LC (GC Corporation, Tokyo, Japan), a resin-modified GIC; Dyract (Dentsply Ltd, Konstanz, Germany), a compomer; Spectrum (Dentsply Ltd, Konstanz, Germany), a composite resin] on the growth of four obligate anaerobic bacteria (Fusobacterium nucleatum, Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia) using the inhibitory ADT. Findings indicated no statistically significant overall differences in the response of the black-pigmented Bacteroides species. Spectrum had more antibacterial effect against F. nucleatum than Dyract. Fuji II LC was ineffective against F. nucleatum. However, positive control plates showed bacterial growth in all cases.

29