Fluoride-releasing acrylics

Formulation and characterization of antibacterial orthodontic adhesive

OBJECTIVE

The objective of this study was to formulate experimental orthodontic bracket adhesives and test their mechanical properties, fluoride release and antibacterial activity.

METHODS

Four experimental antibacterial orthodontic bracket adhesives were prepared with different compositions of synthesized antibacterial monomers replacing total 5% of dental monomers in the control Transbond XT (3M): 5%C11, 3.5%C11+1.5%C2, 5%C16, and 3.5%C16+1.5%C2. Transbond XT alone was used as control. These groups were used to bond premolar brackets to extracted premolars. Shear bond strength (SBS) was tested using an Instron machine. For antibacterial test, disk specimens (10mm diameter, 1mm thick, n=4) were fabricated and incubated with cultures of cariogenic Streptococcus mutans for 48h, and following gentle sonication, S. mutans biofilms in colony-forming-units (CFU) on the disks were enumerated by plating on agar medium. The data were analyzed using ANOVA and Tukey test (α=0.05).

RESULTS

All experimental groups had similar shear bond strength (no significant difference) to the control. All experimental groups showed significant inhibitory effect against S. mutans biofilm formation, when compared to the control, but there was no significant difference between experimental groups.

CONCLUSION

Antibacterial orthodontic adhesive can be fabricated to have similar mechanical properties but better caries-inhibitory effect than current adhesive.

Evaluation of Fluoride-Releasing Dental Materials by Means of in Vitro and in Vivo Demineralization Models: Reaction Paper

It is essential that we understand the dose-response mechanisms of fluoride delivered intra-orally at sites in intimate contact with dental tissues. Many studies show that extremely low levels of fluoride can inhibit caries. However, few of these studies provide a direct comparison between fluoride release and the inhibition of secondary caries. For this, laboratory, animal, and in situ caries models are required which can predict clinical efficacy. This paper supplements Dr. Erickson's presentation (Erickson and Glasspoole, 1995) by illustrating the adaptation of currently used demineralization and caries models to the development and evaluation of fluoride-containing resin materials. As representative of this class of material, those which release by ion-exchange are reviewed. It is concluded that model systems designed for topical fluorides and non-fluoride dental materials can be adapted for use with fluoride-releasing materials. Further, the use of materials with a long history of clinical efficacy as inhibitors of marginal caries, such as the silicates, is a useful means of determining target values for developing new fluoride-releasing materials. The minimum concentration of F- that must be maintained in the immediate vicinity of a material to provide caries protection at localized sites is not yet known. Nor is it known what combination of release rate, pattern of release, and duration of release is needed to optimize either localized or full-mouth protection. These issues deserve closer examination to aid our understanding of F- action when delivered from dental materials, so that improved caries model systems can be designed for use with dental materials.

Review of Fluoride Release and Secondary Caries Reduction by Fluoridating Composites

Secondary caries is one of the main reasons to replace restorations. Due to the pressure to eliminate or reduce the number of amalgam restorations in many countries, fluoride-releasing composites have gained in importance. This review limits itself to information relevant to secondary caries near fluoride-releasing anterior or posterior composites. Although many parameters are very important in composite functioning, a weak spot near a filling is always the interface and the locally present interfacial gap between the composite and the hard tissues, where secondary caries takes place due to plaque action. Relevant parameters such as the amount of fluoride released in vitro in μg.cm-2, the rate of fluoride release, and the period of fluoride release are compared for several composites. In vitro F release has been measured for some fluoridating composites for more than five years. Unfortunately, F release in vivo or in situ cannot be measured adequately.

The fluoride released by the composites considered is partly taken up by the surrounding tissues, partly released to the saliva, and partly efficacious in possible marginal gaps and defects. A major part of this paper pertains to in vitro, in situ, and in vivo secondary caries reduction experiments. In vitro caries reductions in the order of 40% from F-releasing composites vs. controls have been found. In in situ model investigations under plaque and saliva conditions, secondary caries reduction percentages of between 40 and 50% have been experimentally measured in gaps in enamel near F composites.

Novel protein-repellent and biofilm-repellent orthodontic cement containing 2-methacryloyloxyethyl phosphorylcholine

The objectives of this study were to develop the first protein-repellent resin-modified glass ionomer cement (RMGI) by incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC) for orthodontic applications, and to investigate the MPC effects on protein adsorption, biofilm growth, and enamel bond strength. MPC was incorporated into RMGI at 0% (control), 1.5%, 3%, and 5% by mass. Specimens were stored in water at 37°C for 1 and 30 days. Enamel shear bond strength (SBS) was measured, and the adhesive remnant index (ARI) scores were assessed. Protein adsorption onto the specimens was determined by a micro bicinchoninic acid method. A dental plaque microcosm biofilm model with human saliva as inoculum was used. The results showed that adding 3% of MPC into RMGI did not significantly reduce the SBS (p > 0.1). There was no significant loss in SBS for RMGI containing 3% MPC after water-aging for 30 days, as compared to 1 day (p > 0.1). RMGI with 3% MPC had protein adsorption that was 1/10 that of control. RMGI with 3% MPC greatly reduced the bacterial adhesion, and lactic acid production and colony-forming units of biofilms, while substantially increasing the medium solution pH containing biofilms. The protein-repellent and biofilm-repellent effects were not decreased after water-aging for 30 days. In conclusion, the MPC-containing RMGI is promising to reduce biofilms and white spot lesions without compromising orthodontic bracket-enamel bond strength. The novel protein-repellent method may have applicability to other orthodontic cements, dental composites, adhesives, sealants, and cements to repel proteins and biofilms. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 949-959, 2016.

Novel dental composites reinforced with zirconia-silica ceramic nanofibers

OBJECTIVE

To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers.

METHODS

Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37°C deionized water for 24h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey's Honestly Significant Differences test used for post hoc analysis.

RESULTS

Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content.

SIGNIFICANCE

Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life.

Novel F-releasing composite with improved mechanical properties

In recent years, the authors have been developing novel fluoride-releasing dental composites containing ternary zirconium fluoride chelates. The aim of this study was to improve the physical and mechanical properties of these composites by improving the formulation of the monomers and photoinitiators. The hypothesis was that reduction of hydrophilic monomers and improvement of the photoinitiators could reduce water sorption and significantly increase the mechanical properties of the composite. The degree of conversion of the composites containing different compositions of photoinitiators was studied by Fourier transform near-infrared spectroscopy (FT-NIR). Ten experimental composites containing different compositions of ethoxylated bisphenol-A dimethacrylate (EBPADMA), 1,6-hexanediol dimethacrylate (HDDMA), triethylene glycol dimethacrylate (TEGDMA), and 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy) phenyl]-propane (BisGMA) were tested for flexural strength, viscosity, and water sorption. The experimental composite containing 20% synthesized fluoride-releasing monomer, 30% BisGMA, 30% EBPADMA, and 20% HDDMA showed significantly higher fluoride release and recharge, but physical and mechanical properties similar to those of the control composite containing 40% BisGMA, 40% EBPADMA, and 20% HDDMA.

Formulation and characterization of a novel fluoride-releasing dental composite

OBJECTIVES

The aims of this study were to formulate a novel fluoride-releasing dental composite and to evaluate its mechanical properties, fluoride release and recharge capabilities, water sorption and solubility.

METHODS

A fluoride-releasing dimethacrylate monomer containing a ternary zirconium fluoride chelate was synthesized. Three experimental fluoride-releasing composites were fabricated with different monomer formulas (wt.%)-(1) Control A: 40 BisGMA/40 TEDMA/20 UEDMA; (2) EXPERIMENTAL: 20 F-releasing monomer/20 BisGMA/40 TEDMA/20 UEDMA; (3) Control B: the same formula as Control A except that it contained 10 wt.% (of total monomer) tetrabutylammonium fluoride (TBAF), which had a fluoride content equivalent to EXPERIMENTAL. All three materials had the same filler content: 55 wt.% silanized fluoroaluminosilicate particles (0.8 microm) and 10 wt.% silanized fumed silica (14 nm). All materials contained 0.17 wt.% camphorquinone (CQ) as a photoinitiator and 0.69 wt.% ethyl-4-dimethylaminobenzoate (4EDMAB) as an accelerator. The materials were tested for fluoride release (for 184 days), fluoride recharge, compressive and flexure strength, water sorption and solubility. The data were analyzed using ANOVA and Tukey-HSD tests, and Kruskal-Wallis test.

RESULTS

The experimental composite had significantly higher fluoride release and fluoride recharge capabilities than both Control composites. It had significantly better physical and mechanical properties than Control B.

SIGNIFICANCE

The combined use of the fluoride-releasing dimethacrylate monomer and fluoride-releasing filler can provide sustained high fluoride release and recharge as well as acceptable mechanical and physical properties. Simply adding organic fluoride salt in the monomer yields composites with poor mechanical and physical properties.

Effect of fluoride varnish on the in vitro bond strength of orthodontic brackets using a self-etching primer system

To reduce the number of steps involved with bonding procedures, manufacturers have simplified adhesive systems by combining the hydrophilic primer and the adhesive, or by combining the etchant, the primer, and the adhesive into 1 bottle and application. The purpose of this study was to investigate the relationship between the shear bond strength of orthodontic brackets to enamel, with or without fluoride varnish, by using either conventional or self-etching primer systems. Forty-eight extracted teeth were divided into 4 groups of 12 teeth each: group 1, fluoride varnish, conventional adhesive; group 2, fluoride varnish, self-etching primer system; group 3, no fluoride varnish, conventional adhesive; and group 4, no fluoride varnish, self-etching primer system. The bonding procedure followed the manufacturers' recommendations for the materials. Precoated adhesive orthodontic brackets were light-cured to the facial surfaces of the teeth and stored in whole human saliva at 37 degrees C for 24 hours. The specimens were subjected to a shear force in a testing machine until failure. The adhesive remnant index was used to score the teeth. Data were analyzed with a 2-way analysis of variance to test for differences in shear bond strength with respect to fluoride varnish and type of adhesive system used. The results showed no difference in bond strength among any of the experimental groups. Similarly, chi-square analysis determined that adhesive remnant index scores were not statistically different. The application of fluoride varnish does not affect the bond strength of orthodontic brackets to enamel with conventional or self-etching primer systems.

Long-term in vitro fluoride release and rerelease from orthodontic bonding materials containing fluoride

The purpose of this study was to compare in vitro long-term (30 month) fluoride release and rerelease rates (after fluoride exposure) from 3 orthodontic bonding materials containing fluoride and 1 without fluoride. Ten samples of each material (Python, TP Orthodontics, LaPorte, Ind; Assure, Reliance Orthodontic Products, Itasca, Ill; Fuji Ortho LC, GC America, Alsip, Ill; and Transbond XT, 3M Unitek, Monrovia, Calif) were fabricated and stored in deionized distilled water at 37 degrees C. Five samples had fluoride-release rates measured at days 546, 637, 730, 821, and 913 after initial fabrication, and 5 samples were exposed to fluoride (Nupro 2% NaF gel, Dentsply Canada, Woodbridge, Ontario, Canada) for 4 minutes at day 535 and had measurements taken on days 546, 548, 552, 575, 637, 730, 821, and 913. To prevent cumulative measurements, the storage solutions were changed 24 hours before measurement. Statistically significant differences were found in fluoride-release rates (P <.0001), with Fuji Ortho LC releasing the most fluoride, followed by Python and Assure at all time points in the nonfluoride exposed group. In the fluoride-exposed group, there were significant differences in fluoride release (P <.0001), with Fuji Ortho LC releasing the most fluoride. A "burst-effect" pattern of fluoride release was seen after fluoride exposure for all materials. It was concluded that Fuji Ortho LC, Assure, and Python might have sufficient long-term fluoride-release rates to reduce white spot formation, and all are recommended as suitable fluoride-releasing orthodontic bonding materials.

Compressive strength, fluoride release and recharge of fluoride-releasing materials

The compressive strength, fluoride releases and recharge profiles of 15 commercial fluoride-releasing restorative materials have been studied. The materials include glass ionomers (Fuji IX, Ketac Molar, Ketac Silver, and Miracle Mix), resin-modified glass ionomers (Fuji II LC Improved, Photac-Fil, and Vitremer), compomers (Compoglass, Dyract AP, F2000, and Hytac) and composite resins (Ariston pHc, Solitaire, Surefil and Tetric Ceram). A negative linear correlation was found between the compressive strength and fluoride release (r(2)=0.7741), i.e., restorative materials with high fluoride release have lower mechanical properties. The fluoride-releasing ability can be partially regenerated or recharged by using a topical fluoride agent. In general, materials with higher initial fluoride release have higher recharge capability (r(2)=0.7088). Five equations have been used in curve fitting to describe the cumulative fluoride release from different materials. The equation [F](c)=[F](I)(1-e(-bt))+betat best describes the cumulative fluoride release for most glass ionomers, resin-modified glass ionomers, and some high fluoride-releasing compomers and composites, whereas [F](c)=[F](I)/(t(1/2)+t)+alphat best describes the cumulative fluoride release for most compomers and composite resins. The clinic applications of different fluoride-releasing materials have also been discussed.

Fluoride release from new light-cured orthodontic bonding agents

The purpose of this study was to compare the rates of fluoride release with time from 1 nonfluoridated and 3 fluoride-containing orthodontic bonding materials in distilled water and artificial saliva. Materials tested were Assure (Reliance Orthodontic Products, Itasca, Ill), Fuji Ortho LC (GC, Tokyo, Japan), Python (TP Orthodontics, LaPorte, Ind), and Transbond XT (3M Dental Products, Monrovia, Calif). Ten specimens of each material type were stored in distilled water, and 10 of each type were stored in artificial saliva at 37 degrees C. Fluoride release was measured with an ion-specific electrode. Readings were taken periodically for a total time period of 6 months. At day 1, Assure released the most fluoride into distilled water (66.2 microg/cm(2)) and into artificial saliva (65.8 microg/cm(2)), followed by Fuji Ortho LC (25.9 microg/cm(2); 18.8 microg/cm(2)), Python (6.3 microg/cm(2); 4.2 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The fluoride release rates were highest during the first days of testing, declining to lower but more stable levels. At the end of 6 months, Fuji Ortho LC released the most fluoride (3.8 microg/cm(2); 3.5 microg/cm(2)) followed by Assure (3.1 microg/cm(2); 2.8 microg/cm(2)), Python (2.6 microg/cm(2); 1.7 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The type of storage medium did not dramatically affect fluoride release. The second part of the study, undertaken after a year of sample storage, tested the 20 samples of Assure for a further 2-week period, after exposure to running and still distilled water. Although fluoride release rates declined with time, they were still higher than the 1.5 microg/cm(2) level that is referenced as inhibiting decalcification of enamel in a clinical environment. Release rates were similar in running and still water at all time points. Throughout the 6-month period, all 3 fluoride-containing materials had rates of fluoride release that could theoretically inhibit decalcification of enamel.

Fluoride pit and fissure sealants: a review

There are two methods of fluoride incorporation into fissure sealants. In the first method, fluoride is added to the unpolymerized resin in the form of a soluble fluoride salt that releases fluoride ions by dissolution, following sealant application. In the second method, an organic fluoride compound is chemically bound to the resin and the fluoride is released by exchange with other ions (anion exchange system). This report reviews the literature on the effectiveness of all the fluoride-releasing sealants--commercial and experimental--that have been prepared using either the former or the latter method of fluoride incorporation. There is evidence for equal retention rates to conventional sealants and for ex vivo fluoride release and reduced enamel demineralization. However, further research is necessary to ensure the clinical longevity of fluoride sealant retention and to establish the objective of greater caries inhibition through the fluoride released in saliva and enamel.

In vivo biocompatibility of an acrylic, fluoride-releasing, anion-exchange resin

This study evaluated the biocompatibility of an unfilled, fluoride-releasing acrylic resin by subcutaneous implantation in guinea pigs. The experimental fluoride resin was compared to a nonfluoride, dental pit and fissure sealant (DELTON) of similar composition. Thirty-four male albino guinea pigs received four Teflon tubes each, implanted in the dorsal area. The tubes were open at both ends, three contained the experimental fluoride resin and one held the nonfluoride resin. The tubes and surrounding tissue were excised in 1-2 cm blocks, by necropsy, at 14 and 84 days. Histological evaluation showed that inflammatory response was none-to-slight at 14 days for 95% of the fluoride and 100% of the nonfluoride specimens. Five percent of the fluoride specimens produced a moderate tissue response. At 84 days, inflammatory response was none-to-slight for 82.5% of the fluoride and 61.5% of the commercial nonfluoride specimens, while 17.5% of the fluoride and 38.5% of the nonfluoride specimens produced moderate tissue responses. Chi-squared analysis and Fisher's Exact test revealed no statistically significant difference (p less than or equal to 0.05) in tissue response between the two resins at either 14 or 84 days. Hence it is concluded that the experimental, fluoride-releasing resin produces a very mild subcutaneous tissue response and that its biocompatibility is comparable to that of a widely used nonfluoride dental resin. It can, therefore, be considered as having a high potential for biological safety as a dental restorative resin or adhesive, or for other biomedical applications.

Long-term fluoride release of some orthodontic bonding resins: a laboratory study

OBJECTIVES

The present study compared the amounts and profiles of long term fluoride release from four commercial direct bonding resins (Light-Bond, Reliance Orthodontic Products; Rely.a. Bond, Reliance Orthodontic Products; Orthon, Orthon Dental Inc.; Fluor Ever, Macro-Chem Corporation) and one glass ionomer cement (Ketac-Cem, Espe).

METHODS

The specimens were equilibrated in double-deionized water at 37 degrees C. At predetermined intervals, and up to 560 days, the fluoride concentration of the equilibrated solution was determined with a fluoride ion selective electrode. For Light-Bond and Rely.a. Bond two batches were studied and the amount of fluoride released in a 0.1 mol/L NaCl solution was also determined. Differences in the fluoride release profiles due to batch, type of solution and time were determined with a three-factor mixed design ANOVA with repeated measures on one factor.

RESULTS

The fluoride release profiles of the orthodontic adhesives studied differ markedly. Initially, Fluor Ever and Ketac-Cem release comparable amounts of fluoride which are greater than those released by Orthon. After a few weeks the amounts of fluoride released by Ketac-Cem and Orthon become comparable, but are considerably higher than those released by Fluor Ever. During the first days of the elution, the amount of fluoride released by Light-Bond equals that of Orthon, but then decreases below the determination limit of the analytical method within half a year. No difference was found between the fluoride release profiles in water and the NaCl solution. However, the fluoride release profiles apparently depend on the batch. For Rely.a. Bond, the amount of fluoride released is smaller than the detection limit for the fluoride analysis.

SIGNIFICANCE

The fluoride release of the orthodontic adhesives investigated markedly depends on the mechanisms responsible for the fluoride release process.

Resin composites in dentistry: the monomer systems

The present review outlines the history of monomers used in resin composites, motivates further development, and highlights recent and ongoing research reported in the field of dental monomer systems. The monomer systems of most present-day resin composites are based on BisGMA, developed some 40 years ago, or derivatives of BisGMA. In the remaining resin composites, urethane monomers or oligomers are used as the basis of the monomer system. The main deficiencies of current resin composites are polymerization shrinkage and insufficient wear resistance under high masticatory forces. Both factors are highly influenced by the monomer system, and considerable efforts are being made around the world to reduce or eliminate these undesirable properties. The use of fluoride-releasing monomer systems, some of which are under investigation, has been suggested to mitigate the negative effects of marginal gaps formed in consequence of polymerization shrinkage. The very crux of the problem has also been approached with the synthesis of potentially low-shrinking/non-shrinking resin composites involving ring opening or cyclopolymerizable monomers. By the use of additives with a supposed chain transfer agent function, monomer systems have been formulated that improve the degree of conversion of methacrylate double bonds and mechanical properties. Many promising monomer systems have been devised, the implementation of which may be expected to improve the longevity of resin composite fillings and expand the indications for resin composites.

An investigation into the fluoride release of a variety of orthodontic bonding agents

The purpose of this study was to compare the fluoride release from a variety of orthodontic bonding agents. Fluoride release into de-ionized water was measured over a 20-week period. Material based on the fluoride exchange resin was also tested in a saline solution. Fluoride release from a variety of orthodontic bonding agents was compared and the amount of release found to be highly variable. Glass ionomer-based materials showed substantially greater fluoride release when compared with resin-based materials. The presence of anions (Cl-) did not improve the release from fluoride exchange resin. Glass ionomer/resin hybrid material (Vitrabond) released the greatest amount of fluoride.

Dental materials related to prevention--fluoride incorporation into dental materials: reaction paper

Rather than a specific commentary to Dr. Rawls' presentation, this reaction paper discusses the general concept of fluoride addition to dental materials. The genesis of the concept is reviewed, but more important is a critique of the rationale for the deliberate addition of fluoride to dental materials. Researchers and practicing dentists should realize that if the principal reason for the addition of fluoride is to prevent dental caries, the ultimate test of that rationale is a controlled clinical trial. Thus, although a number of questions need to be answered when fluoride is introduced into dental materials, the most important is: Does it inhibit dental caries?

Preventive dental materials: sustained delivery of fluoride and other therapeutic agents

In the 1940's, it was observed that silicate restorative cements were seldom associated with secondary caries. Fissure sealants, designed to protect caries-prone surfaces, appeared in the 1960's. The 1970's and 1980's have seen an increasing emphasis on the use of dental materials for preventive purposes. Glass ionomers, the modern version of silicates, release fluoride and have been available for some time. Polymeric materials that release various therapeutic agents are currently under development for use in topical anesthetic, endodontic, prosthodontic, and periodontal applications. An attachable membrane-reservoir device for oral fluoride delivery will soon be available for general clinical use. Several fluoride-releasing filling and adhesive resins have recently been marketed. These materials are the leading edge of a new class of preventive materials that serve as controlled-release and/or site-specific sources of therapeutic agents. This trend is expected to continue, and the near future should see the introduction of additional oral sustained-delivery systems for use in periodontal and other applications.

Biocompatibility testing of an experimental fluoride releasing resin using human gingival epithelial cells in vitro

Cell culture is a valuable method of evaluating the biocompatibility of new dental materials. The purpose of this study was to compare the in vitro biocompatibility of an experimental fluoride composite resin with fluoride and non-fluoride-releasing materials currently available. The dental materials tested were: MQ Silicate (silicate cement), KETAC-CEM and FUJI (type II glass ionomer cements), VISIO DISPERS (a light-cured, nonfluoridated, microfilled composite resin), and FR-17 (an experimental fluoride-releasing composite resin). The Smulow-Glickman (S-G) human gingival epithelial cell line, which exhibits semidifferentiated characteristics, was used in the study as a test system. Biocompatibility was quantified by counting the viable cells per unit area remaining after 24 and 48 h at two radial distances from cured specimens immersed in the cell culture medium. The test materials were observed to be most toxic to cells nearest the materials. A Time-Distance Cytotoxicity Index (TDCI) was calculated to relate the percentage of dead cells to viable cells at each diffusion distance for each exposure time compared to a nontoxic control. The relative toxicity ranking of the materials tested based on the TDCI was VISIO DISPERS (91%), FUJI (82%), FR-17 (30%), MQ Silicate (23%), and KETAC-CEM (10%), which exhibited the least toxicity. The cytotoxicity of the experimental resin FR-17 was within the range of cytotoxicity of currently accepted restorative materials.