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Recent advances in the use of glass ionomers: bone substitutes

Recentes avanços em relação ao uso de <a NAME="home"></a>ionômeros de vidro: substitutos ósseos

Abstracts

The purpose of this study is to update the reader upon the latest scientific trends concerning the use of glass ionomer cements (GICs). These materials which have been found of large clinical application in dentistry worldwide, have recently been successfully tested as bone substitutes in minor surgical procedures. The new perspectives of the use of glass ionomer as an osteoconductive material is analysed in the light of its biological properties as a restorative material.

Bone substitutes; Glass ionomer cement


A proposta deste estudo foi a de atualizar o leitor sobre os mais recentes estudos relacionados aos cimentos de ionômero de vidro. Estes materiais, que vêm sendo largamente empregados em todo o mundo durante muitos anos na Odontologia, têm sido testados com sucesso em procedimentos de cirurgia menor como substitutos ósseos. As propriedades biológicas apresentadas pelo ionômero de vidro como material restaurador foram tomadas como fundo para traçar as perspectivas de seu uso como material osseocondutor.

Substitos ósseos; Cimentos de ionômero de vidro


Materiais Dentários

Recent advances in the use of glass ionomers: bone substitutes Recentes avanços em relação ao uso de ionômeros de vidro: substitutos ósseos

Luiz Antonio SALATA* * Professor Doutor e ** Assistentes do Departamento de Cirurgia e Traumatologia Buco-Maxilo-Facial e Periodontia da Faculdade de Odontologia de Ribeirão Preto - USP.

Cássio Edvard SVERZUT** * Professor Doutor e ** Assistentes do Departamento de Cirurgia e Traumatologia Buco-Maxilo-Facial e Periodontia da Faculdade de Odontologia de Ribeirão Preto - USP.

Samuel Porfírio XAVIER** * Professor Doutor e ** Assistentes do Departamento de Cirurgia e Traumatologia Buco-Maxilo-Facial e Periodontia da Faculdade de Odontologia de Ribeirão Preto - USP.

SALATA, L. A.; SVERZUT, C. E.; XAVIER, S. P, Recent advances in the use of glass ionomers: bone substitutes. Rev Odontol Univ São Paulo, v. 13, n. 2, p. 203-207, abr./jun. 1999.

The purpose of this study is to update the reader upon the latest scientific trends concerning the use of glass ionomer cements (GICs). These materials which have been found of large clinical application in dentistry worldwide, have recently been successfully tested as bone substitutes in minor surgical procedures. The new perspectives of the use of glass ionomer as an osteoconductive material is analysed in the light of its biological properties as a restorative material.

UNITERMS: Bone substitutes; Glass ionomer cement.

INTRODUCTION

The use of biomaterials for bone substitution, augmentation and repair has long gained clinical acceptance in many areas of orthopaedics and dentistry. Metals, ceramics, polymers and composites are commonly used in orthopaedic surgery and in reconstructive surgery of the head and neck. Metals are mainly used for fracture fixation devices in the form of rods, pins, screws and plates. The replacement or reconstruction of bones using metals is currently in disuse as the availability of new ceramics and polymer/composite materials have proved to be better tolerated by the tissues. In dentistry, effort has been directed towards the development of bone implant materials not only for applications in alveolar ridge augmentation but, also, for periodontal bony defects, immediate tooth root replacement, coatings for dental metal implants and maxillofacial reconstruction. During recent years the effort has been concentrated on the search for a biocompatible material which could replace bone or even stimulate its growth for use in reconstructive surgery. The increased understanding about the properties of ceramic bone substitute materials, associated with promising perspectives regarding the use of glass ionomer cements (GICs) as a new material for bone substitution, have raised hopes for significant advances in the repair of alveolar bony defects and for alveolar ridge augmentation techniques.

The Biocompatibility of Glass Ionomer Cements

The GICs were first introduced by WILSON; KENT27 (1971) as an attempt to develop an ideal restorative material for the replacement of tooth tissue. The GIC is obtained from an acid-basic reaction in which the basic component is a calcium aluminosilicate glass containing fluoride, and the acid is a homopolymer or copolymer of alkenoic acids28. Since there are many types of glasses and a wide range of polyacids with cement-forming capability, the combinations of GIC are numerous.

It is known that a number of inorganic substances can leach from set glass cements. Of these substances, silica, calcium phosphate, fluoride, and aluminium are the most important18,19. Silica is naturally present in food and water and though its effect in humans is not yet well established, it has not been linked with any biocompatibility problems. Calcium phosphate is the main inorganic constituent of both bone and teeth and the effect of leaching would be expected to be biologically beneficial, even considering the small concentration of this compound released from the material. Fluoride is released from GICs for a sustained period of time that may last for at least 18 months in restorative procedures29. Despite the long-lasting period of fluoride release, and hence, the possible concern regarding fluoride toxicity, there has been some evidence suggesting that the fluoride may exert a beneficial effect on new-bone formation10,15. Aluminium remains as a doubtful substance that could affect the reported excellent biocompatibility of GICs, as it is known to be biologically harmful at certain concentrations. Indeed, when the biocompatibility of GICs was tested in vitro under varying conditions of fluoride and aluminium ion release, the latter appeared to be more important than fluoride in determining the biocompatibility of these cements (R. HILL, personal communication). However, despite the reported accumulation of aluminium observed in osteoblasts cultivated in vitro in the presence of GIC, the cells exhibited apparently normal physiological activity and no signs of toxicity were observed as determined by light and scanning electron microscopy17. This result suggests that the amount of aluminium released from GIC could be biologically acceptable under such circumstances. In a recent review by BROOK; HATTON4 (1998) the authors have assembled enough data to conclude that unset GIC can release large amounts of polyacid and ions from the bulk into a receptor area to produce soft tissue damage, as well as all forms of GIC should be prevented from interacting with neural tissue. With regard to the latter warning, fatal cases in which GIC was applied in otoneurosurgery were reported to happen as a consequence of possibly massive release of aluminium ions into the cerebrospinal fluid.

GICs as Bone Substitutes

While the biocompatibility of GIC as a restorative material has been widely documented1,8,21,23,25,31, the evidence that GICs exhibited potential for use in direct contact with bone tissue was first demonstrated by JONCK et al.12 in 1989. In this study Ketac-OÔ has been inserted into cavities created through baboons tibia and compared to poly-methyl methacrylate, a bone cement largely used for hip prostheses fixation. The authors have concluded that glass-ionomer cement might promote a dynamic surface chemistry within the bone, which ultimately induced a favourable environment for bone mineral precipitation. The responses of bony elements to this composite were later determined, following an in vitro comparative study in which fluoro-alumino-silicate based GIC, hydroxyapatite (HA) and tri-calcium phosphate (TCP) were found to exhibit similar bone integration properties6. However, despite the optimism generated by these initial positive findings, concern still remained regarding the possible toxicity associated with the use of GIC observed in this latter study and others6,13.

For use as a particulate bone substitute, one variant of GIC (Ionogranâ, Germany) has been produced in the form of ionomeric microimplant (IM) granules containing, silicon as SiO 35%, aluminium as Al2O3 30%, calcium as CaO 15%, fluorine 10%, sodium as Na2O 3%, and phosphorous as P2O5 7%, with a copolymer of polyacrylic/maleic acid (50% aqueous solution). Once in contact with the tissue, the bone cement is formed by a chemical reaction between the aluminosilicate glass and the aqueous solution of the acid (co-polymer). The acid chemically attacks the surface of glass particles leaching metal cations, typically calcium and aluminium, into the matrix. The outer layer of the glass particles just depleted of ions is degraded to a silica gel. At this time a sufficient number of metal ions have been accumulated in the liquid phase to cause gelation. Consequently, set GICs are hybrid materials consisting of degraded glass particles surrounded by a silica-rich layer in a hydrogel matrix11. The mechanism involved in GIC-induced bone formation is still unclear. It has been assumed that the glass consists of both mullite (Al6Si5O13) structural units and fluororapatite structural units which might serve as bonding agents between the bone mineral and the glass across the bone-cement interface30. Using both in vitro and in vivo models, IM granules have shown to be colonised by viable osteoblast-like cells on their surface. Detailed examination of the tissue/material interface revealed the presence of an intermediate bonding zone which resembled the bone/HA interface7.

GIC derivatives have also been tested in many in vivo models intended for evaluating their influence on bone remodelling process. Following the implantation of particles of set type-III glass-ionomer cement into the rat dental alveolus immediately after tooth extraction, the histometric analysis of the alveolus content confirmed a progressive new bone formation in parallel with a decrease in the percentage fraction of connective tissue in trial areas around the implants2. The authors have stressed that the material is biologically compatible, being incorporated into the alveolar bone during the healing process (Figure 1). These observations are in agreement with the conclusions reached by BROOK; LAMB3 (1994) who had used particulate IM clinically for the prevention of alveolar bone resorption.

FIGURE 1 –
Photomicrography showing rat’s dental alveolus implanted with set GIC (Vidrion FTM, SS White, Brazil) ground down into particles. In A GIC granule (*) is surrounded by new bone three weeks after tooth extraction. The arrow indicates a layer of bone-forming cells located between the material and the bone matrix. X 56. (By courtesy of Profs. L. G. Brentegani and T. L. Lamano Carvalho, Department of Stomatology, FORP-USP).

When granular forms of both HA and IM were compared upon their relative effectiveness in healing standardised osseous defects in rats, the latter induced a better host response (superior biocompatibility) and led to greater amount of bone to be formed in the surgical defects22. The authors have speculated that fluoroapatite, which would be formed during the process of osteoconduction by IM, would be more resistant to resorption than apatite and, since bone formation is a dynamic process of deposition/resorption, this could account for the greater amount of bone associated with IM than with HA particles. Indeed, there is evidence that the osteoconductive effect of IM is likely to benefit from fluoride in its composition, as fluoride has been shown to stimulate both the proliferation and alkaline phosphatase activity of bone-forming cells9,14,26. Although there has been no consensus in the literature concerning the quality of bone formed with varying fluoride doses, fluoride is used in the treatment of osteoporosis20,24 and, moreover, it has been shown to aid in the osseointegration of IM materials in vivo5, to promote the crystallisation of IM30, and to produce a dose-dependent fluoroapatite crystallisation in contact with bone16.

CONCLUSIONS

The outcome of the use of GIC for bone regeneration purposes has been very encouraging and it seems undoubted from the literature that ionomeric bone substitutes may find application in the same clinical situations as HA, including surgical correction of periodontal bone defects and for ridge augmentation. However, the exact mechanism by which GICs promote osteoconduction is still unclear although scientific evidences have pointed fluoride a great participation in this process. It is known that a number of substances can leach from GICs compounds on neighbouring tissues but the actual role of particularly aluminium, in GIC’s biological performance, remains unveiled. Also, the advantages of fluoroapatite formation over apatite formation, as a result of the use of GIC and HA, respectively, must be clarified in terms of quality of bone formed. For this, well-controlled bio-mechanical studies would be needed.

SALATA, L. A.; SVERZUT, C. E.; XAVIER, S. P. Recentes avanços em relação ao uso de ionômeros de vidro: substitutos ósseos. Rev Odontol Univ São Paulo, v. 13, n. 2, p. 203-207, abr./jun. 1999.

A proposta deste estudo foi a de atualizar o leitor sobre os mais recentes estudos relacionados aos cimentos de ionômero de vidro. Estes materiais, que vêm sendo largamente empregados em todo o mundo durante muitos anos na Odontologia, têm sido testados com sucesso em procedimentos de cirurgia menor como substitutos ósseos. As propriedades biológicas apresentadas pelo ionômero de vidro como material restaurador foram tomadas como fundo para traçar as perspectivas de seu uso como material osseocondutor.

UNITERMOS: Substitos ósseos; Cimentos de ionômero de vidro.

BIBLIOGRAPHIC REFERENCES

1. BLACKMAN, R.; GROSS, M.; SELTZER, S. An evaluation of the biocompatibility of a glass ionomer-silver cement in rat connective tissue. J Endod, v. 15, n. 2, p. 76-79, 1989.

2. BRENTEGANI, L. G.; BOMBONATO, K. F.; LAMANO CARVALHO, T. L. Histological evaluation of the biocompatibility of a glass-ionomer cement in rat alveolus. Biomaterials, v.18, n. 2, p. 137-140, 1997.

3. BROOK, I. M.; LAMB, D. J. Clinical evaluation of ionogran for use in the restoration and treatment of alveolar bone atrophy. In: European Conference on Biomaterials, 11, Pisa, 13-16 Sept. 1994. Proceedings. Pisa: Tipografia Vigo Cursi, 1994. p. 466-468.

4. BROOK, I. M.; HATTON, P. V. Glass-ionomers: bioactive implant materials. Biomaterials, v. 19, n. 4, p. 565-571, 1998.

5. BROOK, I. M.; CRAIG, G. T.; LAMB, D. J. Initial in-vivo evaluation of glass ionomer cements for use as alveolar bone substitutes. Clin. Mater, v. 7, n. 2, p. 295-300, 1991.

6. BROOK, I. M.; CRAIG, G. T.; LAMB, D. J. In vitro interaction between primary bone organ cultures, glass-ionomer cements and hydroxyapatite/tricalcium phosphate ceramics. Biomaterials, v. 12, n. 3, p. 179-186, 1991.

7. BROOK, I. M.; CRAIG, G. T.; HATTON, P. V et al. Bone cell interactions with granular glass ionomer bone substitute material: in vivo and in vitro culture models. Biomaterials, v. 13, n. 10, p. 721-726, 1992.

8. DOHERTY, P. J. Biocompatibility evaluation of glass ionomer cement using cell culture techniques. Clin Mater, v. 7, n. 2, p. 335-340, 1991.

9. FARLEY, J. R.; WERGEDAL, J. E.; BAYLINK, D. J. Fluoride directly stimulates proliferation and ALP activity of bone-forming cells. Science, v. 222, n. 4621, p. 330-332, 1983.

10. HANSSON, T.; ROOS, B. The effect of fluoride and calcium on spinal bone mineral content: a controlled, prospective (3 years) study. Calcif Tissue Int, v. 40, n. 5, p. 315-317, 1987.

11. HATTON, P. V.; BROOK, I. M. Characterisation of the ultrastructure of glass ionomer (poly-alkeonate) cement. Br Dent J, v. 173, n. 8, p. 275-277, 1992.

12. JONCK, L. M.; GROBBELAAR, C. J.; STRATING, H. The biocompatibility of glass-ionomer cement in joint replacement: bulk testing. Clin Mater, v. 4, n. 1, p. 85-107, 1989.

13. KAWAHARA, H.; IMANISHI, Y.; OSHIMA, H. Biological evaluation on glass ionomer cement. J Dent Res, v. 58, n. 3, p.1080-1086, 1979.

14. LUNDY, M. W.; FARLEY, J. R.; BAYLINK, D. J. Characterization of a rapidly responding animal model for fluoride-stimulated bone formation. Bone, v. 7, n. 4, p. 289-293, 1986.

15. MAMELLE, N.; DUSAN, R.; MARTIN, J. L. et al. Risk-benefit ratio of sodium fluoride treatment in primary vertebral osteoporosis. Lancet, v. 2, n. 8607, p. 361-365, 1988.

16. MEHTA, S.; REED, B.; ANTICH, P. Effects of high levels of fluoride on bone formation: an in vitro model system. Biomaterials, v. 16, n. 2, p. 97-102, 1995.

17. MEYER, U.; SZULCZEWSKY, D. H.; BARCKHAUS, R. H. et al. Biological evaluation of an ionomeric bone cement by osteoblast cell culture methods. Biomaterials, v. 14, n. 12, p. 917-924, 1993.

18. NICHOLSON, J. W.; BRAYBROOK, J. H.; WASSON, E. A. The biocompatibility of glass-poly (alkeonate) (glass-ionomer) cements: a review. J Biomater Sci Polym Ed, v. 2, n. 2, p. 277-285, 1991.

19. ÖILO, G. Biodegradation of dental composites/glass-ionomer cements. Adv Dent Res, v. 6, n. 1, p. 50-54, 1992.

20. PAK, C. Y. C.; SAKHAEE, K; ZERWEKH, J. E. et al. Safe and effective treatment of osteoporosis with slow-release sodium fluoride: Augmentation of vertebral mass and inhibition of fractures. J Clin Endocrinol Metab, v. 68, n. 1, p. 150-159, 1989.

21. PLANT, C. G.; TOBIAS, R. S.; BRITTON, A. S. et al. Pulpal response to a glass ionomer luting cement. Br Dent J, v. 165, n. 2, p. 54- 58, 1988.

22. SALATA, L. A.; CRAIG, G. T.; BROOK, I. M. Bone healing following the use of hydroxyapatite or ionomeric bone substitutes alone or combined with a guided bone regeneration technique: an animal study. Int J Oral Maxillofac Implants, v. 13, n. 1, p. 44-451, 1998.

23. SASANALUCKIT, P.; ALBUSTANY, K. R.; DOHERTY, P. J. et al. Biocompatibility of glass ionomer cements. Biomaterials, v. 14, n. 12, p. 906-916, 1993.

24. SÖGAARD, C. H.; MOSEKILDE, Li.; SCHWARTZ, W. et al. Effects of fluoride on rat vertebral bone biomechanical competence and bone mass. Bone, v. 16, n. 1, p. 163-169, 1995.

25. TOBIAS, R. S.; BROWNE, R. M.; PLANT, C. G.; et al. Pulpal response to a glass ionomer cement. Br Dent J, v. 144, n. 11, p. 345- 350, 1978.

26. TURNER, R. T.; FRANCIS, R.; BROWN, D. et al. The effects of fluoride on bone and implant histomorphometry in growing rats. J Bone Miner Res, v. 4, n. 3, p. 477-484, 1989.

27. WILSON, A. D.; KENT, B. E. The glass ionomer cement: a new translucent dental filling material. J Appl Chem Biotechnol, v. 21, n. 11, p. 313-318, 1971.

28. WILSON, A. D.; MCLEAN, J. W. Glass-ionomer cement. Quintessence : Chicago, 1985.

29. WILSON, A. D.; GROFFMANN, D. M.; KUHN, A. T. The release of fluoride and other chemical species from a glass ionomer cement. Biomaterials, v. 6, n. 2, p. 431-434, 1985.

30. WOOD, D.; HILL, R. Glass ceramic approach to controlling the properties of a glass-ionomer bone cement. Biomaterials, v.12, n. 3, p.164-170, 1991.

31. ZETTERQUIST, L.; ANNEROTH, G.; NORDENRAM, A. Glass-ionomer cement as retrograde filling material: an experimental investigation in monkeys. Int J Maxillofac Surg, v. 16, n. 4, p. 459-464, 1987.

Recebido para publicação em 08/06/98

Reformulado em 16/10/98

Aceito para publicação em 29/03/99

  • 1
    BLACKMAN, R.; GROSS, M.; SELTZER, S. An evaluation of the biocompatibility of a glass ionomer-silver cement in rat connective tissue. J Endod, v. 15, n. 2, p. 76-79, 1989.
  • 2
    BRENTEGANI, L. G.; BOMBONATO, K. F.; LAMANO CARVALHO, T. L. Histological evaluation of the biocompatibility of a glass-ionomer cement in rat alveolus. Biomaterials, v.18, n. 2, p. 137-140, 1997.
  • 5
    BROOK, I. M.; CRAIG, G. T.; LAMB, D. J. Initial in-vivo evaluation of glass ionomer cements for use as alveolar bone substitutes. Clin. Mater, v. 7, n. 2, p. 295-300, 1991.
  • 6
    BROOK, I. M.; CRAIG, G. T.; LAMB, D. J. In vitro interaction between primary bone organ cultures, glass-ionomer cements and hydroxyapatite/tricalcium phosphate ceramics. Biomaterials, v. 12, n. 3, p. 179-186, 1991.
  • 8
    DOHERTY, P. J. Biocompatibility evaluation of glass ionomer cement using cell culture techniques. Clin Mater, v. 7, n. 2, p. 335-340, 1991.
  • 9
    FARLEY, J. R.; WERGEDAL, J. E.; BAYLINK, D. J. Fluoride directly stimulates proliferation and ALP activity of bone-forming cells. Science, v. 222, n. 4621, p. 330-332, 1983.
  • 11
    HATTON, P. V.; BROOK, I. M. Characterisation of the ultrastructure of glass ionomer (poly-alkeonate) cement. Br Dent J, v. 173, n. 8, p. 275-277, 1992.
  • 13
    KAWAHARA, H.; IMANISHI, Y.; OSHIMA, H. Biological evaluation on glass ionomer cement. J Dent Res, v. 58, n. 3, p.1080-1086, 1979.
  • 14
    LUNDY, M. W.; FARLEY, J. R.; BAYLINK, D. J. Characterization of a rapidly responding animal model for fluoride-stimulated bone formation. Bone, v. 7, n. 4, p. 289-293, 1986.
  • 15
    MAMELLE, N.; DUSAN, R.; MARTIN, J. L. et al Risk-benefit ratio of sodium fluoride treatment in primary vertebral osteoporosis. Lancet, v. 2, n. 8607, p. 361-365, 1988.
  • 17
    MEYER, U.; SZULCZEWSKY, D. H.; BARCKHAUS, R. H. et al Biological evaluation of an ionomeric bone cement by osteoblast cell culture methods. Biomaterials, v. 14, n. 12, p. 917-924, 1993.
  • 19
    ÖILO, G. Biodegradation of dental composites/glass-ionomer cements. Adv Dent Res, v. 6, n. 1, p. 50-54, 1992.
  • 21
    PLANT, C. G.; TOBIAS, R. S.; BRITTON, A. S. et al Pulpal response to a glass ionomer luting cement. Br Dent J, v. 165, n. 2, p. 54- 58, 1988.
  • 23
    SASANALUCKIT, P.; ALBUSTANY, K. R.; DOHERTY, P. J. et al. Biocompatibility of glass ionomer cements. Biomaterials, v. 14, n. 12, p. 906-916, 1993.
  • 24
    SÖGAARD, C. H.; MOSEKILDE, Li.; SCHWARTZ, W. et al Effects of fluoride on rat vertebral bone biomechanical competence and bone mass. Bone, v. 16, n. 1, p. 163-169, 1995.
  • 25
    TOBIAS, R. S.; BROWNE, R. M.; PLANT, C. G.; et al Pulpal response to a glass ionomer cement. Br Dent J, v. 144, n. 11, p. 345- 350, 1978.
  • 26
    TURNER, R. T.; FRANCIS, R.; BROWN, D. et al The effects of fluoride on bone and implant histomorphometry in growing rats. J Bone Miner Res, v. 4, n. 3, p. 477-484, 1989.
  • 28
    WILSON, A. D.; MCLEAN, J. W. Glass-ionomer cement Quintessence : Chicago, 1985.
  • 29
    WILSON, A. D.; GROFFMANN, D. M.; KUHN, A. T. The release of fluoride and other chemical species from a glass ionomer cement. Biomaterials, v. 6, n. 2, p. 431-434, 1985.
  • 30
    WOOD, D.; HILL, R. Glass ceramic approach to controlling the properties of a glass-ionomer bone cement. Biomaterials, v.12, n. 3, p.164-170, 1991.
  • *
    Professor Doutor e
    **
    Assistentes do Departamento de Cirurgia e Traumatologia Buco-Maxilo-Facial e Periodontia da Faculdade de Odontologia de Ribeirão Preto - USP.
  • Publication Dates

    • Publication in this collection
      08 Dec 1999
    • Date of issue
      Apr 1999

    History

    • Accepted
      29 Mar 1999
    • Reviewed
      16 Oct 1998
    • Received
      08 June 1998
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