- Email: [email protected]
Reducing marginal leakage of posterior composite resin restorations: A review of clinical techniques
Reducing marginal leakage of posterior composite restorations: A review of clinical techniques Gary
S. P. Cheung,
B.D.S.,
resin
M.D.S.*
Universityof Hong Kong, Faculty of Dentistry, HongKong It has been well established that composite resin restorations have leakage at the margins. The polymerization shrinkage of the material and its inadequate adhesion to the cavity walls are the primary causes. Unlike silver amalgam restorations, which are self-sealing with age, the gap at the composite-to-tooth interface tends to persist and invite postoperative sensitivity, adverse pulp reactions, and the development of recurrent caries. Many techniques or materials have been advocated to improve the clinical adaptation of this material and to reduce marginal leakage. They limit the effect of polymerization shrinkage and/or enhance the bonding of the composite material to the tooth structure. This article reviews the clinical techniques and materials that have been suggested and are presently available to improve the marginal quality of composite resins, with special reference to posterior restorations. (J PROSTHET DENT 1990;63:286-8.)
M
arginal leakageseemsto be an inherent shortcoming of all dental restorations.’ Leaky margins may result in postoperative sensitivity,2 invasion by bacteria3-5 and subsequentinflammatory changesin the pul~,~y7 and the development of secondary caries.sg Some restorative materials have a poor initial marginal sealbut showan increasedsealingability with age.Amalgam is an example.lO Compositeresinshave not beenshownto sealmarginswith time. Good marginal adaptation’requires adequate physical and mechanical properties of the filling material and its careful manipulation. A restoration must be strong enough to resist deformation, which may lead to a breakdown of marginalintegrity during function. Compositeresinshrinks on hardening and the shrinkage impedes good marginal adaptati0n.l’ The adhesionof composite resinsto dentin needsimprovement, and the difference in thermal expansionbetween compositeresin and the tooth structure only enhancesmarginal leakage.l2 Light-cured resins provide fast polymerization, but the shrinkage is directed toward the first cured surface. This processproduces profound marginal deficiencies at the gingivoproximal-line angle when the curing light is directed from the occlusal surface.13As long aspolymerization contraction cannot be reduced substantially and the adhesionto dentin is still lacking, the use of composite resin for direct restorations demands careful and thoughtful clinical application. A
Most of this article was included in a dissertation submitted to the Faculty of Dentistry, University of Hong Kong in partial fulfillment of the requirements for the degree of Master of Dental Surgery, 1987. *Lecturer,Departmentof ConservativeDentistry. 10/l/17136
286
number of techniqueshave beenadvocated to enhancethe marginal adaptation, reducing the microleakageof composite restorations.
ACID-ETCH
TECHNIQUE
Acid etching is an effective meansof enhancingthe bond to enamel,reducing marginalleakage.14-”A shortcomingof this technique is its dependenceon the presenceof enamel at the cavity wall for etching. The effect is obviouswhenthe marginsof a restoration are located on cementum in deep proximal cariouslesionsor on the gingival walls of cervical abrasioncavities.i*, I9 Two aspectsof enamel etching have remained controversial. One is the useof an intermediary bonding resin and the other relates to the cavosurface bevel. Intermediary resin has been advocated on the assumptionthat its low viscosity facilitates its penetration into the fine irregularities of the etched enamel surface.20-22 In contrast, composite resins adapt well to etched enamel as do lowviscosity resins, and the variation in the viscosity of the compositemakeslittle difference to the quality of the resin tags.23-25 In photoinitiated systems,usually adequate free monomer is available from the composite paste to penetrate the small volume of pores in an acid-etched enamel surface.With a dry mix of chemically activated composite resin, it is possiblethat the application of a low-viscosity resin may give more reliable bonding.26 Similarly, the necessityof bevelling the enamelmargin before etching hasnot received uniform support. The variation in form of the cavosurfacemargin wasshownto have no significant effect on the marginal leakagearound composite resin restorations.13,27,28On the other hand, some investigators maintain that a highly significant improvement of marginal adaptation wasfound when the cavosurface line angle was increased.2g-31
MARCH
1990
VOLUME
63
NUMBER
3
REDUCING
MARGINAL
BONDING
LEAKAGE
TO DENTIN
A strong durable bond to dentin may withstand the polymerization contraction force of composite resin, thus maintaining a good seal at margins that are finished in dentin. The need for retentive undercuts thus could be eliminated, conserving needed sound tooth structure. Current dentin bonding agents are based on halophosphorus esters of Bis-GMA, methacryloxyethylphenyl phosphate, 4-methacryloxyethyl-trimellitic anhydride, the mixture of glutaraldehyde and hydroxyethyl methacrylate, or the ferric oxalate system developed by Bowen and coworkers.32 The range of in vitro bond strengths of various systems to dentin has been reported to be 0 to 18 MPa.33 However, in vitro bond strengths do not correlate with those in the mouth. The freshly prepared dentin surface is always covered with a film of dentinal fluid, with which the active groups of the dentin adhesives readily and preferentially react. 34 As a result, the in vivo bond strength is weakened. An effective dentin bonding agent should be capable of bonding to dentin in the presence of water and the resultant bond should be resistant to moisture-caused degradation. Commercial dentin adhesives are usually provided by the manufacturers for corresponding composite materials because interchanging of adhesives can produce incompatibility, which may impair the marginal seal and the performance of the restoration.35 This incompatibility may also account for the conflicting results of the in vitro marginal seal obtained with some dentin bonding agents. Consistent, long-lasting, nonleaking margins have not yet been achieved in composite resin restorations that are finished in dentin. There is a need for an effective, durable dentin adhesive agent.
CAVITY
DESIGN
every incremental insertion regimen gives better adaptation along the cervical margin than the bulk placement procedure. In butt-joint cylindrical dentin cavities, no significant difference has been found between the horizontal layered technique and the single bulk insertion technique with regard to the maximum marginal contraction gap that is produced.37p 3s Since the curing light is directed toward the occlusal aspect, a poor gingivoproximal tooth-restoration interface is created because the shrinkage occurs away from the margins.3g A more effective incremental placement technique involves the use of the transparent matrix and light-transmitting wedges. 3gThe first increment is placed on the cervical floor and is cured with the light-transmitting wedge toward the gingival aspect. The material thus shrinks toward the cervical margin. The second and third increments are then placed on and cured from the buccal and lingual aspects. The occlusal portion constitutes the final increment.3g This insertion technique is purported to enhance the marginal adaptation at the cervical margin as well as at other locations.40
SEALING
THE
MARGINAL
GAP
Sealing contraction gaps at the cervical margins of class II composite resin restorations has been proposed.18, 41An unfilled resin is applied to the cervical margin by slowly brushing the resin laterally from one side to another after the composite material has set, but before any finishing procedure. For most teeth so treated the unfilled resin sealed the margin gaps. 41 The integrity and the sealing ability of such margins, however, have not been determined.
SUMMARY
PLACEMENT
Poor marginal adaptation and microleakage, attributable to the polymerization shrinkage of the composite material, have adversely affected the prognosis of posterior composite resin restorations. With the introduction of the acid-etch technique, the problem of microleakage at margins finished on enamel has been largely resolved. The bonding of composite resin to dentin has not reached the stage where the adhesive bond can fully withstand the contraction force without disruption of any part of its margin. Multiple incremental placement appears to be an effective way to reduce, but not eliminate, the microleakage at the margin of a composite restoration. The development of a composite resin with no polymerization contraction or slight curing expansion appears to be an ideal solution for the problems arising from a filling material which shrinks on setting.
Placement of composite resin material in the cavity has received much attention. Multiple incremental placements have been advocated to control polymerization shrinkage, reducing the contraction gap at the margin. However, not
I express my profound gratitude to Professor C. E. Renson, former Head of Department of Conservative Dentistry, University of Hong Kong, for his guidance throughout the period of postgraduate study.
A change in the design of the cavity preparation may reduce marginal leakage in composite restorations. Luescher et a1.36developed a completely new design for class II cavities, which they call the “adhesive preparation.” This cavity preparation takes into account the shrinkage vector of the composite material during polymerization. Experiments on marginal adaptations and leakage patterns have given promising results compared to those with conventional cavity forms. 13,30,36However, the adhesive preparation design is not applicable when an existing restoration is being replaced. Its application is also limited when the cervical margin is located apical to the cementoenamel junction.
INCREMENTAL TECHNIQUE
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
287
CHEUNG
REFERENCES 1. Going RE. Microleakage
2. 3.
4.
5.
6.
around dental restorations: a summarizing review. J Am Dent Assoc 1972;84:1349-57. Brannstrom M. Communication between the oral cavity and the dental pulp associated with restorative treatment. Oper Dent 1984;9:57-68. Brannstrom M, Nyborg H. Presence of bacteria in cavities filled with silicate cement and composite resin materials. Swed Dent J 1971;64:14955. Mejare B, Mejare I, Edwardsson S. Bacteria beneath composite restorations-a culturing and histobacteriological study. Acta Odontol Stand 1979;37:267-75. Quist V. Correlation between marginal adaptation of composite restorations and bacterial growth in cavities. Stand J Dent Res 1980;88:296300. Brannstrom M, Nyborg H. Cavity treatment with a microbicidal fluoride solution: growth of bacteria and effect on the pulp. J PROSTHET DENT 1973;30:303-10.
I. Bergenholtz G, Cox CF, Loesche WJ, Syed SA. Bacteria leakage around dental restorations. Its effect on the pulp. J Oral Path01 1982;11:439-50. 8. Ellis JM, Brown LR. Application of an in vitro cariogenic technique to study the development of carious lesions around dental restorations. J Dent Res 1967;46:403-8. 9. Eriksen HM, Pears G. In vitro caries related to marginal leakage around composite resin restorations. J Oral Rehabil i978;5:15-20. 10. Jodaikin A. Experimental microleakage around aging dental amalgam restorations: a review. J Oral Rehabil 1981;8:517-26. 11. Bergvall 0, Brannstrom M. Measurements of the space between composite resin fillings and the cavity walls. Swed Dent J 1971;64:217-26. 12. Crim GA, Mattingly SL. Evaluation of two methods for assessing marginal leakage. J PROSTHET DENT 1981;45:160-3. 13. Lutz F, Imfeld T, Barbakow F, Iselin W. Optimizing the marginal adaptation of MOD composite restorations. In: Vanherle G, Smith DC, eds. Posterior composite resin dental restorative materials. St Paul: Peter Ssulc, 1985;405-19. 14. Al Rafei S, Moore DL. Marginal adaptation of composite restorations as indicated by a tracer dye. J PROSTHET DENT 1975;34:435-9. 15. Kempler D, Stark MM, Leung RL, Greenspan JS. Enamel-composite interface relative to cavosurface configuration, abrasion and bonding agent. Oper Dent 1976;1:137-45. 16. Raadal M. Microleakage around preventive composite fillings in loaded teeth. Stand J Dent Res 1979;87:390-4. 17. Hembree JH, Taylor TJ. Marginal leakage of visible light-cured composite resin restorations. J PROSTHET DENT 1984;52:790-3. 18. Brannstrom M, Torstensen B, Nordenvall KJ. The initial gap around large composite restoration in vitro: the effect of etching enamel walls. J Dent Res 1984;63:681-4. 19. Phair CB, Fuller JL. Microleakage of composite resin restorations with cementum margins. J PROSTHET DENT 1985;53:161-4. 20. Draughn RA. The effect of thermal cycling on retention of composite restorative [Abstract]. J Dent Res 1976;55:B137. 21. Hembree JH, Andrew JT. In situ evaluation of marginal leakage using an ultraviolet-light-activated resin system. J Am Dent Assoc 1976; 92414-8. 22. Prevost AP, Fuller JL, Peterson LC. The use of an intermediate resin in the acid-etch procedure: retentive strength, microleakage and failure mode analysis. J Dent Res 1982;61:412-8.
288
23. Jorgensen KD, Shimokobe H. Adaptation of resinous restorative materials to acid etched enamel surfaces. Stand J Dent Res 1975;83:31-5. 24. Asmussen E. Penetration of restorative resins into acid etched enamel, I and II. Acta Odontol Stand 1977;35:175-8, and 183-91. 25. Low T, Lee KW, von Fraunhofer JA. The adaptation of composite materials to etched enamel surfaces. J Oral Rehabil 1978;5:349-55. 26. Bowen RL. Composite and sealant resins-past, present, and future, Pediatr Dent 1982;4:10-5. 27. Eliasson ST, Hill GL. Cavosurface design and marginal leakage of composits resin restorations. Oper Dent 197’7;2:55-8. 28. Retief DH, Woods E, Jamison HC. Effect of cavosurface treatment on marginal leakage in class V composite resin restorations. J PROSTHET DENT
1982;47:496-501.
29. Eriksen HM, Buonocore MG. Marginal leakage with different composite restorative materials in viva. Effect of cavity design. J Oral Rehabil 1976;3:315-22. 30. Porte A, Lutz F, Lund MR, Swarm ML, Cochran MA. Cavity designs for composite resins. Oper Dent 1984;9:50-6. 31. Moore DH, Vann WF. The effect of a cavosurface bevel on microleakage in posterior composite restorations. J PROSTHET DENT 1988;59: 21-4.
32. Miller MB, ed. Reality, vol 3, no 2. Houston: Reality Publishing Co, 1988;35-40. 33. Council on Dental Materials, Instruments, and Equipment. Dentine bonding systems: an update. J Am Dent Assoc 1987;114:91-5. 34. Asmussen E, Munksgaard EC. Adhesion of restorative resins to dentinal tissues. In: Vanherle G, Smith DC, eds. Posterior composite resin dental restorative materials. St Paul: Peter Szulc, 1985;217-29. 35. Robinson PB, Moore BK. The effect on microleakage of interchanging dentine adhesives in two composite resin systems in vitro. Br Dent J 198&164:77-g. 36. Luescher B, Lutz F, Ochsenbein H, Muehlemann HR. Microleakage and marginal adaptation in conventional and adhesive class II restorations. J PROSTHET DENT 1977;37:300-9. 37. Hansen EK. Effect of cavity depth and application technique on marginal adaptation of resins in dentine cavities. J Dent Res 1986;65:131921. 38. Azarbal P, Denehy GE. Insertion techniques and adaptation of composite resin to cavity margins. J PROSTHET DENT 1981;46:66-70. 39. Lutz F, Krejei I, Luescher B, Oldenburg TR. Improved proximal margin adaptation of class II composite resin restorations by the use of light-reflecting wedges. Quintessence Int 1986;17:659-64. 40. Lambrechts P, Braem M, Vanherle G. Evaluation of clinical performance for posterior composite resins and dentine adhesives. Oper Dent 198’7;12:53-78. 41. Torstensen B, Brannstrom M, Mattsson B. A new method for sealing composite resin contraction gaps in lined cavities. J Dent Res 1985;64:450-3. Reprint requests to: DR. GARY S. P. CHEUNG DEPARTMENT OF CONSERVATIVE DENTISTRY THE PRINCE PHILIP DENTAL HOSP~AL 34 HOSPITAL RD. SAI YING PUN HONG KONG
MARCH1990
VOLUME~~
NUMBERS
S. P. Cheung,
B.D.S.,
resin
M.D.S.*
Universityof Hong Kong, Faculty of Dentistry, HongKong It has been well established that composite resin restorations have leakage at the margins. The polymerization shrinkage of the material and its inadequate adhesion to the cavity walls are the primary causes. Unlike silver amalgam restorations, which are self-sealing with age, the gap at the composite-to-tooth interface tends to persist and invite postoperative sensitivity, adverse pulp reactions, and the development of recurrent caries. Many techniques or materials have been advocated to improve the clinical adaptation of this material and to reduce marginal leakage. They limit the effect of polymerization shrinkage and/or enhance the bonding of the composite material to the tooth structure. This article reviews the clinical techniques and materials that have been suggested and are presently available to improve the marginal quality of composite resins, with special reference to posterior restorations. (J PROSTHET DENT 1990;63:286-8.)
M
arginal leakageseemsto be an inherent shortcoming of all dental restorations.’ Leaky margins may result in postoperative sensitivity,2 invasion by bacteria3-5 and subsequentinflammatory changesin the pul~,~y7 and the development of secondary caries.sg Some restorative materials have a poor initial marginal sealbut showan increasedsealingability with age.Amalgam is an example.lO Compositeresinshave not beenshownto sealmarginswith time. Good marginal adaptation’requires adequate physical and mechanical properties of the filling material and its careful manipulation. A restoration must be strong enough to resist deformation, which may lead to a breakdown of marginalintegrity during function. Compositeresinshrinks on hardening and the shrinkage impedes good marginal adaptati0n.l’ The adhesionof composite resinsto dentin needsimprovement, and the difference in thermal expansionbetween compositeresin and the tooth structure only enhancesmarginal leakage.l2 Light-cured resins provide fast polymerization, but the shrinkage is directed toward the first cured surface. This processproduces profound marginal deficiencies at the gingivoproximal-line angle when the curing light is directed from the occlusal surface.13As long aspolymerization contraction cannot be reduced substantially and the adhesionto dentin is still lacking, the use of composite resin for direct restorations demands careful and thoughtful clinical application. A
Most of this article was included in a dissertation submitted to the Faculty of Dentistry, University of Hong Kong in partial fulfillment of the requirements for the degree of Master of Dental Surgery, 1987. *Lecturer,Departmentof ConservativeDentistry. 10/l/17136
286
number of techniqueshave beenadvocated to enhancethe marginal adaptation, reducing the microleakageof composite restorations.
ACID-ETCH
TECHNIQUE
Acid etching is an effective meansof enhancingthe bond to enamel,reducing marginalleakage.14-”A shortcomingof this technique is its dependenceon the presenceof enamel at the cavity wall for etching. The effect is obviouswhenthe marginsof a restoration are located on cementum in deep proximal cariouslesionsor on the gingival walls of cervical abrasioncavities.i*, I9 Two aspectsof enamel etching have remained controversial. One is the useof an intermediary bonding resin and the other relates to the cavosurface bevel. Intermediary resin has been advocated on the assumptionthat its low viscosity facilitates its penetration into the fine irregularities of the etched enamel surface.20-22 In contrast, composite resins adapt well to etched enamel as do lowviscosity resins, and the variation in the viscosity of the compositemakeslittle difference to the quality of the resin tags.23-25 In photoinitiated systems,usually adequate free monomer is available from the composite paste to penetrate the small volume of pores in an acid-etched enamel surface.With a dry mix of chemically activated composite resin, it is possiblethat the application of a low-viscosity resin may give more reliable bonding.26 Similarly, the necessityof bevelling the enamelmargin before etching hasnot received uniform support. The variation in form of the cavosurfacemargin wasshownto have no significant effect on the marginal leakagearound composite resin restorations.13,27,28On the other hand, some investigators maintain that a highly significant improvement of marginal adaptation wasfound when the cavosurface line angle was increased.2g-31
MARCH
1990
VOLUME
63
NUMBER
3
REDUCING
MARGINAL
BONDING
LEAKAGE
TO DENTIN
A strong durable bond to dentin may withstand the polymerization contraction force of composite resin, thus maintaining a good seal at margins that are finished in dentin. The need for retentive undercuts thus could be eliminated, conserving needed sound tooth structure. Current dentin bonding agents are based on halophosphorus esters of Bis-GMA, methacryloxyethylphenyl phosphate, 4-methacryloxyethyl-trimellitic anhydride, the mixture of glutaraldehyde and hydroxyethyl methacrylate, or the ferric oxalate system developed by Bowen and coworkers.32 The range of in vitro bond strengths of various systems to dentin has been reported to be 0 to 18 MPa.33 However, in vitro bond strengths do not correlate with those in the mouth. The freshly prepared dentin surface is always covered with a film of dentinal fluid, with which the active groups of the dentin adhesives readily and preferentially react. 34 As a result, the in vivo bond strength is weakened. An effective dentin bonding agent should be capable of bonding to dentin in the presence of water and the resultant bond should be resistant to moisture-caused degradation. Commercial dentin adhesives are usually provided by the manufacturers for corresponding composite materials because interchanging of adhesives can produce incompatibility, which may impair the marginal seal and the performance of the restoration.35 This incompatibility may also account for the conflicting results of the in vitro marginal seal obtained with some dentin bonding agents. Consistent, long-lasting, nonleaking margins have not yet been achieved in composite resin restorations that are finished in dentin. There is a need for an effective, durable dentin adhesive agent.
CAVITY
DESIGN
every incremental insertion regimen gives better adaptation along the cervical margin than the bulk placement procedure. In butt-joint cylindrical dentin cavities, no significant difference has been found between the horizontal layered technique and the single bulk insertion technique with regard to the maximum marginal contraction gap that is produced.37p 3s Since the curing light is directed toward the occlusal aspect, a poor gingivoproximal tooth-restoration interface is created because the shrinkage occurs away from the margins.3g A more effective incremental placement technique involves the use of the transparent matrix and light-transmitting wedges. 3gThe first increment is placed on the cervical floor and is cured with the light-transmitting wedge toward the gingival aspect. The material thus shrinks toward the cervical margin. The second and third increments are then placed on and cured from the buccal and lingual aspects. The occlusal portion constitutes the final increment.3g This insertion technique is purported to enhance the marginal adaptation at the cervical margin as well as at other locations.40
SEALING
THE
MARGINAL
GAP
Sealing contraction gaps at the cervical margins of class II composite resin restorations has been proposed.18, 41An unfilled resin is applied to the cervical margin by slowly brushing the resin laterally from one side to another after the composite material has set, but before any finishing procedure. For most teeth so treated the unfilled resin sealed the margin gaps. 41 The integrity and the sealing ability of such margins, however, have not been determined.
SUMMARY
PLACEMENT
Poor marginal adaptation and microleakage, attributable to the polymerization shrinkage of the composite material, have adversely affected the prognosis of posterior composite resin restorations. With the introduction of the acid-etch technique, the problem of microleakage at margins finished on enamel has been largely resolved. The bonding of composite resin to dentin has not reached the stage where the adhesive bond can fully withstand the contraction force without disruption of any part of its margin. Multiple incremental placement appears to be an effective way to reduce, but not eliminate, the microleakage at the margin of a composite restoration. The development of a composite resin with no polymerization contraction or slight curing expansion appears to be an ideal solution for the problems arising from a filling material which shrinks on setting.
Placement of composite resin material in the cavity has received much attention. Multiple incremental placements have been advocated to control polymerization shrinkage, reducing the contraction gap at the margin. However, not
I express my profound gratitude to Professor C. E. Renson, former Head of Department of Conservative Dentistry, University of Hong Kong, for his guidance throughout the period of postgraduate study.
A change in the design of the cavity preparation may reduce marginal leakage in composite restorations. Luescher et a1.36developed a completely new design for class II cavities, which they call the “adhesive preparation.” This cavity preparation takes into account the shrinkage vector of the composite material during polymerization. Experiments on marginal adaptations and leakage patterns have given promising results compared to those with conventional cavity forms. 13,30,36However, the adhesive preparation design is not applicable when an existing restoration is being replaced. Its application is also limited when the cervical margin is located apical to the cementoenamel junction.
INCREMENTAL TECHNIQUE
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
287
CHEUNG
REFERENCES 1. Going RE. Microleakage
2. 3.
4.
5.
6.
around dental restorations: a summarizing review. J Am Dent Assoc 1972;84:1349-57. Brannstrom M. Communication between the oral cavity and the dental pulp associated with restorative treatment. Oper Dent 1984;9:57-68. Brannstrom M, Nyborg H. Presence of bacteria in cavities filled with silicate cement and composite resin materials. Swed Dent J 1971;64:14955. Mejare B, Mejare I, Edwardsson S. Bacteria beneath composite restorations-a culturing and histobacteriological study. Acta Odontol Stand 1979;37:267-75. Quist V. Correlation between marginal adaptation of composite restorations and bacterial growth in cavities. Stand J Dent Res 1980;88:296300. Brannstrom M, Nyborg H. Cavity treatment with a microbicidal fluoride solution: growth of bacteria and effect on the pulp. J PROSTHET DENT 1973;30:303-10.
I. Bergenholtz G, Cox CF, Loesche WJ, Syed SA. Bacteria leakage around dental restorations. Its effect on the pulp. J Oral Path01 1982;11:439-50. 8. Ellis JM, Brown LR. Application of an in vitro cariogenic technique to study the development of carious lesions around dental restorations. J Dent Res 1967;46:403-8. 9. Eriksen HM, Pears G. In vitro caries related to marginal leakage around composite resin restorations. J Oral Rehabil i978;5:15-20. 10. Jodaikin A. Experimental microleakage around aging dental amalgam restorations: a review. J Oral Rehabil 1981;8:517-26. 11. Bergvall 0, Brannstrom M. Measurements of the space between composite resin fillings and the cavity walls. Swed Dent J 1971;64:217-26. 12. Crim GA, Mattingly SL. Evaluation of two methods for assessing marginal leakage. J PROSTHET DENT 1981;45:160-3. 13. Lutz F, Imfeld T, Barbakow F, Iselin W. Optimizing the marginal adaptation of MOD composite restorations. In: Vanherle G, Smith DC, eds. Posterior composite resin dental restorative materials. St Paul: Peter Ssulc, 1985;405-19. 14. Al Rafei S, Moore DL. Marginal adaptation of composite restorations as indicated by a tracer dye. J PROSTHET DENT 1975;34:435-9. 15. Kempler D, Stark MM, Leung RL, Greenspan JS. Enamel-composite interface relative to cavosurface configuration, abrasion and bonding agent. Oper Dent 1976;1:137-45. 16. Raadal M. Microleakage around preventive composite fillings in loaded teeth. Stand J Dent Res 1979;87:390-4. 17. Hembree JH, Taylor TJ. Marginal leakage of visible light-cured composite resin restorations. J PROSTHET DENT 1984;52:790-3. 18. Brannstrom M, Torstensen B, Nordenvall KJ. The initial gap around large composite restoration in vitro: the effect of etching enamel walls. J Dent Res 1984;63:681-4. 19. Phair CB, Fuller JL. Microleakage of composite resin restorations with cementum margins. J PROSTHET DENT 1985;53:161-4. 20. Draughn RA. The effect of thermal cycling on retention of composite restorative [Abstract]. J Dent Res 1976;55:B137. 21. Hembree JH, Andrew JT. In situ evaluation of marginal leakage using an ultraviolet-light-activated resin system. J Am Dent Assoc 1976; 92414-8. 22. Prevost AP, Fuller JL, Peterson LC. The use of an intermediate resin in the acid-etch procedure: retentive strength, microleakage and failure mode analysis. J Dent Res 1982;61:412-8.
288
23. Jorgensen KD, Shimokobe H. Adaptation of resinous restorative materials to acid etched enamel surfaces. Stand J Dent Res 1975;83:31-5. 24. Asmussen E. Penetration of restorative resins into acid etched enamel, I and II. Acta Odontol Stand 1977;35:175-8, and 183-91. 25. Low T, Lee KW, von Fraunhofer JA. The adaptation of composite materials to etched enamel surfaces. J Oral Rehabil 1978;5:349-55. 26. Bowen RL. Composite and sealant resins-past, present, and future, Pediatr Dent 1982;4:10-5. 27. Eliasson ST, Hill GL. Cavosurface design and marginal leakage of composits resin restorations. Oper Dent 197’7;2:55-8. 28. Retief DH, Woods E, Jamison HC. Effect of cavosurface treatment on marginal leakage in class V composite resin restorations. J PROSTHET DENT
1982;47:496-501.
29. Eriksen HM, Buonocore MG. Marginal leakage with different composite restorative materials in viva. Effect of cavity design. J Oral Rehabil 1976;3:315-22. 30. Porte A, Lutz F, Lund MR, Swarm ML, Cochran MA. Cavity designs for composite resins. Oper Dent 1984;9:50-6. 31. Moore DH, Vann WF. The effect of a cavosurface bevel on microleakage in posterior composite restorations. J PROSTHET DENT 1988;59: 21-4.
32. Miller MB, ed. Reality, vol 3, no 2. Houston: Reality Publishing Co, 1988;35-40. 33. Council on Dental Materials, Instruments, and Equipment. Dentine bonding systems: an update. J Am Dent Assoc 1987;114:91-5. 34. Asmussen E, Munksgaard EC. Adhesion of restorative resins to dentinal tissues. In: Vanherle G, Smith DC, eds. Posterior composite resin dental restorative materials. St Paul: Peter Szulc, 1985;217-29. 35. Robinson PB, Moore BK. The effect on microleakage of interchanging dentine adhesives in two composite resin systems in vitro. Br Dent J 198&164:77-g. 36. Luescher B, Lutz F, Ochsenbein H, Muehlemann HR. Microleakage and marginal adaptation in conventional and adhesive class II restorations. J PROSTHET DENT 1977;37:300-9. 37. Hansen EK. Effect of cavity depth and application technique on marginal adaptation of resins in dentine cavities. J Dent Res 1986;65:131921. 38. Azarbal P, Denehy GE. Insertion techniques and adaptation of composite resin to cavity margins. J PROSTHET DENT 1981;46:66-70. 39. Lutz F, Krejei I, Luescher B, Oldenburg TR. Improved proximal margin adaptation of class II composite resin restorations by the use of light-reflecting wedges. Quintessence Int 1986;17:659-64. 40. Lambrechts P, Braem M, Vanherle G. Evaluation of clinical performance for posterior composite resins and dentine adhesives. Oper Dent 198’7;12:53-78. 41. Torstensen B, Brannstrom M, Mattsson B. A new method for sealing composite resin contraction gaps in lined cavities. J Dent Res 1985;64:450-3. Reprint requests to: DR. GARY S. P. CHEUNG DEPARTMENT OF CONSERVATIVE DENTISTRY THE PRINCE PHILIP DENTAL HOSP~AL 34 HOSPITAL RD. SAI YING PUN HONG KONG
MARCH1990
VOLUME~~
NUMBERS