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BIS-GMA–BASED RESINS IN DENTISTRY: ARE THEY SAFE? KARL-JOHAN SÖDERHOLM, D.D.S., M.PHIL., ODONT.DR.; ANGELO MARIOTTI, D.D.S., PH.D.
Background. The authors critically surveyed
that short-term administration of BIS-GMA and/or research dealing with the release of resin components bisphenol A in animals or cell cultures can induce from dental composites and the potential of these changes in estrogen-sensitive organs or cells.
agents to mimic or disrupt estrogenic cell responses.
However, considering the dosages and routes of ad- Types of Studies Reviewed. The
ministration and the modest response of estrogen- studies reviewed included those on synthetic methods sensitive target organs, the authors conclude that the used to make bisphenol A glycidyl methacrylate, or short-term risk of estrogenic effects from treatments BIS-GMA, and the biological effects of this resin in using bisphenol A–based resins is insignificant.
cell culture and animals. The estrogenic effect of Long-term effects need to be investigated further.
bisphenol A was targeted because bisphenol A is Clinical Implications. Commonly used
present as an impurity in some resins (BIS-GMA) dental resins should not be of concern to the general and as a degradation product from other resins public; however, pharmacological evaluation of den- (bisphenol A dimethacrylate, or BIS-DMA).
tal materials is needed to ensure biologically safe and Results. The outcomes of this review revealed
therapeutically effective substances.
“If we had a reliable way to label our toys good and bad, it would be easy to regulate technology wise- ly. But we can rarely see far enough ahead to know which road leads to damnation. Whoever concernshimself with big technology, either to push it forward or to stop it, is gambling in human lives.” —Freeman Dyson, “Disturbing the Universe,” 1979
During World War II, German researchers de- polymerization process of the epoxy resin. To veloped a chemical process that could be used to overcome this problem, Bowen attached methyl cure dental methacrylates at room temperature.1,2 methacrylate groups to the end groups of the Despite initial successes, the clinical results re- epoxy resin, thereby converting the epoxy resin to ported during the mid-1950s showed that chemi- a dimethacrylate.9,10 The experimental outcome cally cured methacrylate restorations were asso- was successful and resulted in a new resin called ciated with increases in discoloration, recurrent bisphenol A glycidyl methacrylate, or BIS-GMA, tooth decay and pulp reactions.3-5 These initial side effects were attributed to polymerization Bowen’s resin had some important advantages, including reduced shrinkage during polymeriza- tion and the ability to form cross-links (which are searchers added inert filler particles to the self- stronger than linear polymers) during polymer- curing methacrylate resin.6,7 To improve strength ization. However, the higher viscosity of BIS- and adhesiveness of the resinous restorations, GMA made it more difficult to add filler to the Bowen8 explored the possibility of using epoxy monomer and to mix the chemically cured com- resins (diglycidyl ether of bisphenol A) mixed with posite. To solve this problem, different monomers silica particles. The in vitro results were promis- with lower viscosities (for example, triethylene- ing, but the presence of moisture inhibited the glycol dimethacrylate, or TEGDMA) were added Copyright 1998-2001 American Dental Association. All rights reserved.
Figure 1. The bisphenol A molecule (top) is estrogenic. Under clinical conditions, esterase present in salivacan break ester linkages (arrows). If the bisphenol A glycidyl methacrylate, or BIS-GMA, molecule (center) isattacked by esterase, no bisphenol A will form. However, if the ester linkages of the bisphenol A dimethacry-late, or BIS-DMA, molecule (bottom) are attacked, bisphenol A can form.
Copyright 1998-2001 American Dental Association. All rights reserved.
CREATING BIS-GMA
Inhibitory
Protein Complex

Transcription-
Activating
Hormone-
Binding

pounds containing two hydroxygroups in para positions. Onesuch derivative, bearing two Hinge Region
DN A-Binding Domain
bisphenol A, has been used bysome manufacturers during syn-thesis of BIS-GMA.10 Because ofthe estrogenic effect of bisphenolA, it seemed reasonable to sus- GMA–containing materials,bisphenol A molecules could bepresent that could cause an es-trogenic response.
Release of Inhibitory
Protein Complex

DN A-Binding Site Exposed
bisphenol A groups present inthe BIS-GMA molecule are ster-ically hindered and if themonomer is pure and does notcontain any impurities from the Figure 2. The unbound or free hormone enters the cell by diffusion and binds to macromolecules called receptors. When binding occurs, the re- ceptor releases an inhibitory protein complex, and the DNA-binding siteof the receptor becomes exposed and ready to bond to the DNA.
derstand the potential risks as-sociated with BIS-GMA, we Chemistry. In 1965, Bowen
Copyright 1998-2001 American Dental Association. All rights reserved.
Problems. From a biological
THE ESTROGEN FAMILY
AND HOW IT WORKS
Copyright 1998-2001 American Dental Association. All rights reserved.
Cell culture experiments.
BIS-GMA EPISTEMOLOGY
Copyright 1998-2001 American Dental Association. All rights reserved.
In situ experiments.
Absorption, metabolism
and excretion: pharmacoki-
netics. Questions remain
Copyright 1998-2001 American Dental Association. All rights reserved.
Copyright 1998-2001 American Dental Association. All rights reserved.
CONCLUSION
Herstellung von Zahnersatzteilen, insbeson- Tokes L, Feldman D. Bisphenol-A: an estro- genic substance is released from polycarbon- ate flasks during autoclaving. Endocrinology Patentschr German patent 760351: 1940.
tors. Verfaren zur Schnellpolymerisation von conjugated androgens and estrogens by the Patentschr German patent 975072: 1941.
and after human chorionic gonadotropin. J 3. Caul HJ, Schoonover IC. Color stability of direct filling resins. JADA 1953;56:448-52.
pain and changes in the dental pulp following the insertion of fillings. Br Dent J 1954;96:9- cell dynamics in the periodontium. Crit Rev 5. Hedegård B. Cold-polymerizing resins: a 26. Ke FC, Ramirez VD. Binding of proges- clinical and histological study. Acta Odontol terone to nerve cell membranes of rat brain using progesterone conjugated to 125I-bovine material and method. U.S. patent 2558139: 27. Lan NC, Chen JS, Belelli D, Pritchett 7. Rose EE, Lal J, Green R, Cornell J.
DB, Seeburg PH, Gee KW. A steroid recogni- Direct resin filling materials: coefficient of tion site is functionally coupled to an ex- thermal expansion and water sorption of poly- pressed GABA(A)-benzodiazepine receptor.
8. Bowen RL. Use of epoxy resins in restora- Alexander N. Progesterone and 17-alpha hy- tive materials. J Dent Res 1956;35:360-9.
droxyprogesterone: novel stimulators of calci- 9. Bowen RL. Properties of a silica-rein- forced polymer for dental restorations. JADA 10. Bowen RL, inventor. Method of prepar- CY, Trout JJ. Polyamines mediate androgenic stimulation of calcium fluxes and membrane methacrylate groups linked by hydroxy glyc- transport in rat heart myocytes. Circ Res erol groups. U.S. patent 3179623. April 1965.
11. Cueto EI, Buonocore MG. Sealing of pits and fissures with an adhesive resin: its use in caries prevention. JADA 1967;75(1):121-8.
31. Löe H, Silness J. Periodontal disease in Hunter JK. Restoration of fractured and hy- pregnancy. I. Prevalence and severity. Acta poplastic incisors by the acid etch resin tech- 32. Löe H. Periodontal changes in pregnan- 13. Zachrisson BZ. The acid etch technique women: a longitudinal clinical study. Odontol Silverstone LM, Dogon IL, eds. Proceedings of an international symposium on . . . the acid pregnancy. J Periodontol 1974;45:641-3.
14. Rochette AL. Attachment of a splint to R, et al. Periodontal condition of pregnant enamel of lower anterior teeth. J Prosthet 36. Maier AW, Orban B. Gingivitis in preg- Miullineaux AL. A laboratory and clinical comparison of silicate cements and a direct- filling resin: a progress report. J Prosthet al. Environmental estrogens and reproductive 16. Lambrechts P, Braem M, Vanherle G.
health: a discussion of the human and envi- Accomplishments and expectations with pos- ronmental data. Reprod Toxicol 1997;11:465- terior composite resins. In: Vanherle G, Smith DC, eds. Posterior composite resin dental 38. Benet LZ, Kroetz DL, Sheiner LB.
restorative materials. Utrecht: Peter Szulc Pharmacokinetics: the dynamics of drug ab- sorption, distribution and elimination. In: Dr. Söderholm is a professor, University of 17. Olea N, Pulgar R, Perez P, et al.
Florida, College of Dentistry, Department of Estrogenicity of resin-based composites and sealants used in dentistry. Environ Health Gilman’s the pharmacologic basis of thera- Gainesville, Fla. 32610-0446. Address reprint genic agents without the phenanthrene nucle- Dr. Mariotti is an associate professor of pe- nisms of drug action and the relationship be- riodontology, College of Dentistry, and phar- tween drug concentration and effects. In: presentation. J Dent Res 1979;58:1504-6.
20. Niinimaki A, Rosberg J, Saari S.
Allergic stomatitis from acrylic compounds.
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therapeutics. In: Hardman JG, Limbird LE, Copyright 1998-2001 American Dental Association. All rights reserved.
Molinoff PB, Ruddon RW, Gilman AG, eds.
leachability in model resin composites. Eur J a single dermal application and of a single Goodman & Gilman’s the pharmacologic basis of therapeutics. 9th ed. New York: McGraw- 41. Mariotti A, Hefti A. Agents for the con- Saliva and growth factors: the fountain of JW. Network conversion and leachability of trol of supragingival plaque. In: Craig CR, Stitzel R, eds. Modern pharmacology. 5th ed.
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49. Mariotti A, Söderholm K-J, Johnson S.
The in vivo effects of bisGMA on murine uter- different dental materials [thesis].
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45. Müller H, Olsson S, Söderholm KJ. The bis[4(2,3-epoxypropoxy)phenyl]propane, the 56. Ferracane JL. Elution of leachable com- effect of comonomer composition, silane heat- diglycidyl ether of bisphenol A (DGEBPA) in the mouse. Part I. A comparison of the fate of Copyright 1998-2001 American Dental Association. All rights reserved.

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