The Journal of the American Dental Association
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J Am Dent Assoc, Vol 134, No 6, 721-728.
© 2003 American Dental Association
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by BRAGA, R. R.
Right arrow Articles by FERRACANE, J. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by BRAGA, R. R.
Right arrow Articles by FERRACANE, J. L.
Related Collections
Right arrow Restoratives

RESEARCH

Contraction stress of flowable composite materials and their efficacy as stress-relieving layers



ROBERTO R. BRAGA, D.D.S., M.S., Ph.D., THOMAS J. HILTON, D.D.S. and JACK L. FERRACANE, Ph.D.

Background. The authors compared the polymerization contraction stress produced by flowable resin-based composites with stress values produced by nonflowable composites. They also measured the stress reduction produced by placing a precured layer of flowable composite under a nonflowable composite.

Methods. The authors first tested four flowable and six nonflowable composite materials for contraction stress in a tensiometer. In the second part of the study, they applied a 1.4-millimeter–thick layer of flowable composite or unfilled resin and pre-cured it in the test apparatus to assess the stress relief produced by a low-modulus material during light curing of a subsequent layer of highly filled composite. Flexural moduli of the precured materials were determined via a three-point bending test.

Results. The stress values ranged between 6.04 and 9.10 megapascals. The authors found no significant differences in stress between flowable and nonflowable composites. Microfilled composites produced lower contraction stress than did hybrids. The flexural modulus of the flowable composites varied between 4.1 and 8.2 GPa. Regarding the effect of a precured layer of composite on contraction stress, the authors observed significant reductions with only one of the flowable materials and with the unfilled resin.

Conclusions. The flowable composites produced stress levels similar to those of nonflowable materials. Most of the flowable materials tested did not produce significant stress reductions when used under a nonflowable composite.

Clinical Implications. Using a flowable resin-based composite as a restorative material is not likely to reduce the effects of polymerization stress. When used in a thin layer under a nonflowable composite, the stress reduction depended on the elastic modulus of the lining material.

When dental resin-based composite is cured in a three-dimensional constrained cavity preparation, stresses are developed as a result of the polymerization contraction that accompanies setting. These stresses may be present within the composite, and may be transferred to the bonded margins of the restoration. The magnitude of these potentially damaging stresses is a function of certain characteristics of the composite and of the cavity preparation.

Using a flowable resin-based composite as a restorative material is not likely to reduce the effects of polymerization stress.

One important characteristic is the filler concentration. In resin-based composites, the filler content is directly related to mechanical properties and wear resistance.1,2 The presence of high filler levels also is fundamental to reducing shrinkage of the composite during polymerization.3 Because of its influence on both elastic modulus and volumetric shrinkage, the amount of filler present in a resin-based composite is a major factor in terms of polymerization contraction stress development,4 which ultimately will affect the marginal integrity of the restoration.5

Low-viscosity (that is, flowable) resin-based composites contain 20 to 25 percent less filler than do nonflowable materials.6 Several studies have shown substantial differences in elastic modulus and volumetric shrinkage between flowable and conventional hybrid composite materials.7–9 Although the study findings are in agreement, there is no information available about the behavior of flowable composites in regard to development of contraction stress. While the high volumetric shrinkage produced by these materials may lead to high stress values, it is possible that their low elastic modulus (that is, high strain capacity) could reduce the stress buildup and help maintain the marginal seal of the restoration.

Kemp-Scholte and Davidson10 conducted a study in which they demonstrated that the development of cervical gaps in Class V restorations was directly related to the elastic modulus of the composite. In fact, microleakage studies comparing flowable with nonflowable composite materials have shown better results with the flowable material.11,12 However, Jang and colleagues13 compared a flowable composite material with a packable composite material and did not find any significant differences in microleakage between the materials (with or without load cycling).

Flowable composite materials also have been used as intermediate materials (or liners) between the adhesive layer and a nonflowable composite material.14–16 Kemp-Scholte and Davidson10,17 showed that placement of an intermediate layer of unfilled resin or resin-modified glass ionomer improved marginal sealing of the restoration and reduced, by up to 50 percent, the contraction stress generated by a subsequent layer of high-modulus composite material. Choi and colleagues18 found that the application of multiple layers of unfilled resin led to stress reductions between 27 and 37 percent in comparison with the stress registered when only one layer of unfilled resin was applied. Although the use of flowable composites as intermediate materials was shown to be an effective way of reducing voids at the interface between the restoration and the tooth,19,20 the results of microleakage studies seem controversial.

Some authors have found that a flowable composite layer is advantageous in regard to reducing microleakage.21,22 Hilton and Quinn23 found a non-significant trend toward reduced microleakage in thermocycled Class II restorations when flowable composite was used in a thin layer under a nonflowable resin-based composite. Other authors, however, have failed to show differences in microleakage between restorations with a layer of flowable composite material and those without a layer.20,24,25

The inconsistent findings associated with the use of flowable composites can be explained in two ways. First, despite their low elastic modulus, the contraction stress produced by some flowable composites could be sufficiently high because of their high volumetric shrinkage, leading to adhesive failure at the interface between the tooth and the composite when the material is used as a thin intermediate layer or to fill the entire cavity. Second, although flowable composites generally have a lower elastic modulus than do nonflowable composites, the elastic modulus for some materials might not be low enough to provide significant stress relief, as has been observed in studies using unfilled resins.10,18

Therefore, the first aim of our study was to determine whether flowable composites produce lower polymerization contraction stress than do nonflowable composites. A second aim was to test the hypothesis that the use of a precured layer of flowable composite material can significantly reduce the contraction stress generated by a subsequent increment of nonflowable composite material.


   MATERIALS AND METHODS
TOP
MATERIALS AND METHODS
RESULTS
 DISCUSSION
 CONCLUSION
 
Determination of the contraction stress in flowable and nonflowable composites. Table 1Go describes the materials tested. All of the testing procedures were performed by one of the investigators (R.B.). In the first part of the study, the contraction stress of four flowable composites (three hybrids and one microfill) and six nonflowable composites (five hybrids and one microfill) was determined using a tensiometer.4,26 The investigator cut glass rods (5 millimeters in diameter) into two lengths: 5 and 12 mm. Both flat surfaces of the 5-mm rods were sandblasted with 250-micrometer alumina, rinsed, dried and silanated (RelyX Primer, 3M ESPE, St. Paul, Minn.). One of the ends and the lateral surface of the 12-mm rods were sandblasted and silanated, while the opposite end was polished to allow light transmission through the glass.


View this table:
[in this window]
[in a new window]
  		TABLE 1 RESIN-BASED COMPOSITE MATERIALS TESTED.

 
Using light-cured composite, the researcher bonded the 5-mm glass rod to a steel stub that was connected to the load cell of the testing machine; the 12-mm glass rod then was bonded into the perforation of a steel fixture attached to the cross-head of the testing machine. The fixture had a slot into which a 7-mm–diameter light tip from the curing unit was introduced and placed into contact with the polished end of the glass rod.

The researcher applied a thin layer of unfilled resin (Scotchbond Multi-Purpose Plus, 3M ESPE) to the sandblasted and silanated surfaces of both glass rods, and light-cured them for 30 seconds. The composite was applied between the glass rods, and the actuator was moved to set the distance between the glass surfaces to 0.83 mm. This configuration produced a ratio of bonded-to-nonbonded surface area—or C-Factor—equal to 3.26 The investigator triggered photoactivation immediately after beginning the data collection process. The resin-based composite was light-cured for 60 seconds. The actual irradiance reaching the composite layer was 390 milliwatts per square centimeter (energy density, 23.4 joules/cm2).

The researcher kept the distance between the glass rods constant via a feedback system that used a noncontact transducer (with an accuracy of 0.25 µm). Contraction force was monitored for 10 minutes. The researcher tested five specimens for each material. The maximum contraction stress was calculated by dividing the maximum contraction force by the cross-sectional area of the glass rod. After 10 minutes, the specimen was pulled to failure (that is, the glass rod was moved up until the composite debonded from the glass) to make sure that no partial debonding occurred between the composite and the glass surfaces during the test.

Determination of stress reduction by flowable composites. In the second part of the study, the investigator applied a 1.4-mm–thick layer of flowable resin-based composite (± standard deviation, 0.16 mm) to the bonding surface of the lower glass rod, and light-cured it for 60 seconds at 600 mW/cm2 (energy density, 36 J/cm2). A removable plastic ring was formed around the glass rod to contain the flowable composite. The 1.4-mm thickness is higher than the 0.5- to 1.0-mm thickness recommended by some authors.15,16 However, the investigator found it difficult to keep the thickness below 1.0 mm during preparation of the specimens, so he used a more reproducible (thicker) layer.

The investigator then applied a layer of nonflowable hybrid composite (Filtek Z250, 3M ESPE) over the flowable composite precured layer and pressed the specimen until it reached a thickness of 0.83 mm. The rest of the procedure was identical to that described for the first part of the study. Figure 1Go shows a diagram of the contraction stress test set up. The investigator also prepared control groups in which the precured layer was built with a nonflowable hybrid composite (Filtek Z250) or unfilled resin.



View larger version (27K):
[in this window]
[in a new window]
  		Figure 1. Diagram of contraction stress test apparatus. mm: Millimeters.

 
To correlate the magnitude of contraction stress relief with the stiffness of the precured layer, the investigator determined the flexural modulus of the composite materials through a three-point bending test, according to ISO 4049.27 Quadrangular cross-section beams (25 x 2 x 2 mm, n = 5) were prepared in glass tubes and cured in a Triad II unit (Dentsply Trubyte, York, Pa.) from two opposite surfaces, for 40 seconds each. The specimens were stored in distilled water for 24 hours at 37 C. The distance between the supports in the flexural test was 20 mm. The test was performed with a cross-head speed of 0.13 mm/minute. The researcher calculated flexural modulus (in gigapascals) using the following formula:


where l is the distance between the supports (in millimeters), b is the width and h is the height of the beam (both in millimeters) and F/d is the slope in the initial linear region of the load-deflection curve. Cross-head motion was used to estimate deflection.

We used one-way analysis of variance and Tukey’s test (with a global significance level of .05) to analyze contraction stress and flexural modulus results.


   RESULTS
TOP
MATERIALS AND METHODS
 RESULTS
DISCUSSION
 CONCLUSION
 
Contraction stress values ranged from 6.04 to 9.10 MPa (Figure 2Go). The mean stress was 8.19 MPa for the group of flowable resin-based composites and 7.93 MPa for the nonflowable resin-based composites. Contraction stress was significantly lower for Heliomolar and Heliomolar Flow (Ivoclar Vivadent, Schaan, Liechtenstein) than it was for the other composites, except for Esthet-X (Dentsply Caulk, Milford, Del.). We found no further significant differences among the materials tested.



View larger version (36K):
[in this window]
[in a new window]
  		Figure 2. Mean contraction stress (in megapascals) of flowable and nonflowable resin-based composite materials (n = 5). Bars connected by a horizontal line are not significantly different (analysis of variance/Tukey’s test; P > .05). * See Table 1Go for manufacturers.

 
The contraction stress of Filtek Z250 applied directly onto the glass rod was 8.32 MPa (Table 2Go). This value was reduced to 6.46 MPa when Filtek Z250 was applied over a precured layer of the same material. When Filtek Z250 was applied over a precured layer of flowable composite, the contraction stress value ranged from 5.26 to 6.34 MPa. When Filtek Z250 was applied over a precured layer of unfilled resin, the stress value lowered to 3.84 MPa.


View this table:
[in this window]
[in a new window]
  		TABLE 2 MEAN CONTRACTION STRESS ACHIEVED BY APPLYING FILTEK Z250 OVER A PRECURED LAYER OF COMPOSITE OR UNFILLED RESIN.

 
Flowable composites demonstrated a wide range in regard to flexural modulus (from 4.1 to 8.2 GPa) (Table 2Go). The values for the nonflowable composite (Filtek Z250) and for the unfilled resin were 12.3 GPa and 2.1 GPa, respectively. Figure 3Go shows the regression plot of the percentage of contraction stress reduction as a function of flexural modulus of the precured layer. We calculated stress reduction on the basis of the stress value achieved with Filtek Z250 when applied directly over the glass rod (Table 2Go). The curve showed a good fit with the logarithmic function (r2 = .968), indicating that the use of an initial precured layer of composite, either flowable or nonflowable, or unfilled resin produced a reduction in stress.



View larger version (34K):
[in this window]
[in a new window]
  		Figure 3. Regression plot of contraction stress reduction of nonflowable composite (Filtek Z250, 3M ESPE, St. Paul, Minn.) when applied over a precured layer of composite (or unfilled resin) versus flexural modulus of the precured material.

 
When comparing the stress values obtained when flowable composites were used to build the initial layer with the values obtained when the nonflowable composite was used as the precured material, we found the reduction to be from 2 to 19 percent. The stress reduction was significant only for Filtek Flow. In contrast, when unfilled resin was used to build the precured layer, the stress was 42 percent lower than the mean value obtained when a precured layer of nonflowable composite material was used.


   DISCUSSION
TOP
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
CONCLUSION
 
The stress generated by polymerization contraction of the resin-based composite material is the first threat to the restoration’s marginal integrity. A recent study showed a correlation between contraction stress and marginal leakage in Class V composite restorations.28 The magnitude of the stress is related to the configuration and compliance (that is, the ability to deform under external forces) of the cavity,26 as well as to certain characteristics of the restorative composite material. The ability of the polymer to rearrange and delay or relieve stress buildup (known as flow capacity) has been shown to influence the magnitude of the final contraction stress.29 In addition, the elastic properties and magnitude of the polymerization contraction affect shrinkage stress.

According to Hooke’s law, stress is determined by the stiffness of the material when subjected to a given strain. Therefore, the higher the elastic modulus and the polymerization shrinkage of the composite, the higher the contraction stress will be. These two factors seem to act synergistically, as a previous study has shown that above a certain level, small increases in the degree of conversion produced substantial increases in stress.30 However, the individual contributions of these two factors are not well-known.

Condon and Ferracane4 verified a positive linear correlation between filler content and contraction stress in commercial composite materials, suggesting that the stiffness of the material would be the dominant factor. On the other hand, Watts and colleagues31 found that increasing the filler content in experimental composites led to increased modulus, reduced shrinkage and reduced stress. Flowable composites produce high volumetric shrinkage and low elastic modulus compared with nonflowable composites.7,8 Because we found no noticeable differences in this study between stress levels registered by flowable and nonflowable composites, it appears that the influence of the low elastic modulus on stress development of flowable composites is surpassed by their high contraction strain, resulting in stress levels that are equivalent to those obtained with nonflowable materials.

Microfilled composites versus hybrids. The stress values produced by the two microfilled composites tested (Heliomolar and Heliomolar Flow) were significantly lower than those obtained with the hybrids. This finding agrees with that of a study by Condon and Ferracane.4 Microfilled composites contain lower filler levels than do hybrids, which accounts for their low elastic modulus. However, much of the filler is added to the resin matrix in prepolymerized clusters, and, for this reason, shrinkage levels produced by these materials are similar to those produced by more heavily filled composites.7

The fact that we found no difference in contraction stress between flowable and nonflowable composite materials suggests that the risk of the restoration’s debonding from the cavity wall as a result of polymerization contraction is similar for both types of composite material. However, the higher strain capacity of flowable composites may still be advantageous to protect the restoration from thermal and mechanical stresses that could cause further damage to the interface between the restoration and the tooth. The strain capacity of flowable composites during the thermocycling procedure might explain the superior performance of a flowable composite over nonflowable composites found in one microleakage study.11 Another study, however, did not find any differences between a flowable and a packable composite in samples that were thermocycled and subjected to cyclic loading.13 More in vitro and clinical studies are necessary to clarify this issue.

Flexural modulus values. The flowable composite materials tested exhibited a wide range of flexural modulus values, which correlated well with filler content. Filtek Z250 contains the highest filler content among the nonflowable materials tested and exhibited a flexural modulus of 12.3 GPa. PermaFlo DC (Ultradent Products, South Jordan, Utah), the flowable with the highest filler content, exhibited the highest modulus among the flowable composites tested. Filtek Flow and AELITEFLO (Bisco, Schaumburg, Ill.) demonstrated statistically similar flexural modulus values. Heliomolar Flow, the material with the lowest filler content, demonstrated the lowest flexural modulus value.

These findings agree with those of other studies. Sabbagh and colleagues,9 using a three-point bending test, reported values between 1.4 and 4.3 GPa for five flowable composites after 24 hours of storage. Labella and colleagues,7 using a dynamic test method, found values between 6.5 and 12.5 GPa among 13 materials.

Compared with the results for Filtek Z250 cured directly between the glass rods, the use of a precured thin layer of any composite produced a significant stress reduction. These stress reductions are the result of an increase in the compliance of the testing system.32 Compliance is the reciprocal of the stiffness of the material. This reduction in stress cannot be attributed to poor bonding between the precured layer and the nonflowable composite, because the force values registered when the samples were pulled to failure were in the same range as those observed in the first part of the study (approximately 13 MPa).

Resin-based composites with lower elastic modulus will produce greater compliance in this test, thereby producing lower stress values than those observed with a more rigid setup, such as curing directly between high-modulus glass rods. However, the use of a precured layer of flowable composite generally did not result in significant stress reduction compared with values for the experimental group using Filtek Z250 as a pre-cured material, although the use of a relatively thick precured layer should have a greater likelihood of demonstrating a significant stress relief for the materials with lower elastic modulus. Only when we used unfilled resin as an intermediate material did we observe significant stress reduction, which is in agreement with the results of previous studies.17,18

Three of the flowable composites tested (Heliomolar Flow, AELITEFLO and Filtek Flow) exhibited similar reductions in stress (Table 2Go), but only for Filtek Flow was the stress value statistically lower than the value obtained with a precured layer of nonflowable composite. For the other two flowable composites, statistical analysis did not reveal significant differences. In regard to flexural modulus, one might expect the material with the lowest mean value (Heliomolar Flow: 4.1 GPa) to produce the most significant stress relief. However, Filtek Flow (5.3 GPa) was the only material resulting in significant stress reduction when used as a precured material. These results suggest that flowable composites with flexural moduli in the range of 4.1 to 5.3 GPa may exhibit inconsistent behavior in terms of having sufficient strain capacity to provide significant stress relief.

These findings may help explain the variety of results observed in studies testing the effect of an intermediate layer of flowable composite on microleakage. The composition of flowable composites varies widely. Besides filler content, variables such as resin blend, concentration of photosensitizers and accelerators, and type of photosensitizers and accelerators account for differences in elastic modulus and strain capacity, which ultimately determine the percentage of stress relief they allow.1,33

One of the flowable composites tested (PermaFlo DC) demonstrated a relatively high flexural modulus, and its performance in terms of stress reduction was close to that of the nonflowable composite (Filtek Z250). The other three flowable composites tested appeared to be on the verge of producing significant stress relief. Clinically, their behavior will depend on specific conditions (for example, the geometry and compliance of the cavity).

Other factors could increase the strain capacity of the intermediate layer. For example, an insufficient degree of conversion could reduce the elastic modulus of the flowable composite layer.34 The thickness of the intermediate layer also has been shown to influence the stress relief.17 However, under conditions in which adequate cure is produced in thin layers of material, significant stress relief cannot be guaranteed when flowable composites with elastic moduli of approximately 5 GPa and higher are used as an intermediate layer.

The contraction stress values produced by flowable composites were similar to those exhibited by nonflowable composites (for both hybrids and microfilled materials). In addition, the results of our study do not provide enough evidence to support the use of a precured intermediate layer of flowable composite as a means of significantly relieving the contraction stress produced by a subsequent increment of nonflowable composite. It appears that substantially higher stress reductions might be achieved if flowable composites are formulated in a way to produce elastic moduli close to the value shown by the unfilled resin.


   CONCLUSION
TOP
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
 
Based on the results of this in vitro study, we conclude that despite their lower elastic modulus, flowable resin-based composites generate polymerization contraction stress values similar to those produced by nonflowable resin-based composites. For most of the flowable composites tested, we found that the use of an intermediate precured layer did not significantly reduce the contraction stress generated by a subsequent layer of nonflowable composite material.


  
TOP
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
 

Dr. Braga is an assistant professor, Depto. de Materiais Dentarios da FOUSP, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-900, Brazil, e-mail "rrbraga{at}usp.br". Address reprint requests to Dr. Braga.


Dr. Hilton is an associate professor, Department of Biomaterials and Biomechanics, Oregon Health and Science University, School of Dentistry, Portland.


Dr. Ferracane is a professor and chair, Department of Biomaterials and Biomechanics, Oregon Health and Science University, School of Dentistry, Portland.


This study was supported in part by FAPESP (The State of São Paulo Research Foundation, grant 1999/11543-6), NIH/NIDCR grant DE 07079 and Ultradent Products, South Jordan, Utah.

  1. Chung KH, Greener EH. Correlation between degree of conversion, filler concentration and mechanical properties of posterior composite resins. J Oral Rehabil 1990;17:487–94.[Medline]

  2. Condon JR, Ferracane JL. In vitro wear of composite with varied cure, filler level, and filler treatment. J Dent Res 1997;76:1405–11.[Abstract/Free Full Text]

  3. Munksgaard EC, Hansen EK, Kato H. Wall-to-wall polymerization contraction of composite resins versus filler content. Scand J Dent Res 1987;95:526–31.[Medline]

  4. Condon JR, Ferracane JL. Assessing the effect of composite formulation on polymerization stress. JADA 2000;131:497–503.

  5. Uno S, Shimokobe H. Contraction stress and marginal adaptation of composite restorations in dentinal cavity. Dent Mater J 1994;13:19–24.[Medline]

  6. Bayne SC, Thompson JY, Swift EJ Jr., Stamatiades P, Wilkerson M. A characterization of first-generation flowable composites. JADA 1998;129:567–77.

  7. Labella R, Lambrechts P, Van Meerbeek B, Vanherle G. Polymerization shrinkage and elasticity of flowable composites and filled adhesives. Dent Mater 1999;15:128–37.[Medline]

  8. Price RB, Rizkalla AS, Hall GC. Effect of stepped light exposure on the volumetric polymerization shrinkage and bulk modulus of dental composites and an unfilled resin. Am J Dent 2000;13:176–80.[Medline]

  9. Sabbagh J, Vreven J, Leloup G. Dynamic and static moduli of elasticity of resin-based materials. Dent Mater 2002;18:64–71.[Medline]

  10. Kemp-Scholte CM, Davidson CL. Marginal integrity related to bond strength and strain capacity of composite resin restorative systems. J Prosthet Dent 1990;64:658–64.[Medline]

  11. Ferdianakis K. Microleakage reduction from newer esthetic restorative materials in permanent molars. J Clin Pediatr Dent 1998;23:221–9.

  12. Fruits TJ, VanBrunt CL, Khajotia SS, Duncanson Jr. MG. Effect of cyclical lateral forces on microleakage in cervical resin composite restorations. Quintessence Int 2002;33:205–12.[Medline]

  13. Jang KT, Chung DH, Shin D, García-Godoy F. Effect of eccentric load cycling on microleakage of Class V flowable and packable composite resin restorations. Oper Dent 2001;26:603–8.[Medline]

  14. Behle C. Flowable composites: properties and applications. Pract Periodontics Aesthet Dent 1998;10:347–51.[Medline]

  15. Unterbrink GL, Liebenberg WH. Flowable resin composites as "filled adhesives": literature review and clinical recommendations. Quintessence Int 1999;30:249–57.[Medline]

  16. Jackson RD, Morgan M. The new posterior resins and a simplified placement technique. JADA 2000;131:375–83.

  17. Kemp-Scholte CM, Davidson CL. Complete marginal seal of Class V resin composite restorations effected by increased flexibility. J Dent Res 1990;69:1240–3.[Abstract/Free Full Text]

  18. Choi KK, Condon JR, Ferracane JL. The effects of adhesive thickness on polymerization contraction stress of composite. J Dent Res 2000;79:812–7.[Abstract/Free Full Text]

  19. Estafan D, Estafan A, Leinfelder KF. Cavity wall adaptation of resin-based composites lined with flowable composites. Am J Dent 2000;13:192–4.[Medline]

  20. Chuang S, Liu J, Chao C, Liao F, Chen YM. Effects of flowable composite lining and operator experience on microleakage and internal voids in Class II composite restorations. J Prosthet Dent 2001;85:177–83.[Medline]

  21. Tung FF, Estafan D, Scherer W. Microleakage of a condensable resin composite: an in vitro investigation. Quintessence Int 2000;31:430–4.[Medline]

  22. Leevailoj C, Cochran MA, Matis BA, Moore BK, Platt JA. Microleakage of posterior packable resin composites with and without flowable liners. Oper Dent 2001;26:302–7.[Medline]

  23. Hilton TJ, Quinn R. Marginal leakage of Class II composite/flowable restorations with varied cure technique (abstract 502). J Dent Res 2001;80:589.

  24. Jain P, Belcher M. Microleakage of Class II resin-based composite restorations with flowable composite in the proximal box. Am J Dent 2000;13:235–8.[Medline]

  25. Wibowo G, Stockton L. Microleakage of Class II composite restorations. Am J Dent 2001;14:177–85.[Medline]

  26. Feilzer AJ, de Gee AJ, Davidson CL. Setting stress in composite resin in relation to configuration of the restoration. J Dent Res 1987; 66:1636–9.[Abstract/Free Full Text]

  27. International Organization for Standardization. Dentistry—polymer-based filling, restorative and luting materials. Geneva, Switzerland: International Organization for Standardization; ISO/FDIS 4049:2000(E).

  28. Ferracane JL, Mitchem JC. Relationship between composite contraction stress and leakage in Class V cavities. Am J Dent (in press).

  29. Davidson CL, de Gee AJ. Relaxation of polymerization contraction stress by flow in dental composites. J Dent Res 1984;63:146–8.[Abstract/Free Full Text]

  30. Braga RR, Ferracane JL. Contraction stress related to degree of conversion and reaction kinetics. J Dent Res 2002;81:114–8.[Abstract/Free Full Text]

  31. Watts DC, Vogel K, Maroufi AS. Shrinkage stress reduction in resin-composites of increasing particle concentration (abstract 2444). J Dent Res 2002;81:A-308.

  32. Alster D, Venhoven BA, Feilzer AJ, Davidson CL. Influence of compliance of the substrate materials on polymerization contraction stress in thin resin composite layers. Biomaterials 1997;18:337–41.[Medline]

  33. Kawaguchi M, Fukushima T, Horibe T. Effect of monomer structure on the mechanical properties of light-cured composite resins. Dent Mater J 1989;8:40–5.[Medline]

  34. Braem M, Lambrechts P, Vanherle G, Davidson CL. Stiffness increase during the setting of dental composite resins. J Dent Res 1987;66:1713–6.[Abstract/Free Full Text]




This article has been cited by other articles:


Home page
 J. Dent. Res.Home page
F. Goncalves, C.S. Pfeifer, J.L. Ferracane, and R.R. Braga
Contraction Stress Determinants in Dimethacrylate Composites
J. Dent. Res., April 1, 2008; 87(4): 367 - 371.
[Abstract] [Full Text] [PDF]

Home page
 J. Dent. Res.Home page
J.W. Park and J.L. Ferracane
Residual Stress in Composites with the Thin-ring-slitting Approach.
J. Dent. Res., October 1, 2006; 85(10): 945 - 949.
[Abstract] [Full Text] [PDF]

Home page
 J. Dent. Res.Home page
M. Hashimoto, A.J. de Gee, M. Kaga, and A.J. Feilzer
Contraction stress in dentin adhesives bonded to dentin.
J. Dent. Res., August 1, 2006; 85(8): 728 - 732.
[Abstract] [Full Text] [PDF]

Home page
 Crit. Rev. Oral Biol. Med.Home page
R.R. Braga and J.L. Ferracane
ALTERNATIVES IN POLYMERIZATION CONTRACTION STRESS MANAGEMENT
Crit. Rev. Oral. Biol. Med., May 1, 2004; 15(3): 176 - 184.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by BRAGA, R. R.
Right arrow Articles by FERRACANE, J. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by BRAGA, R. R.
Right arrow Articles by FERRACANE, J. L.
Related Collections
Right arrow Restoratives

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS