Mechanical properties, shrinkage stress, cuspal strain and fracture resistance of molars restored with bulk-fill composites and incremental filling technique

The aim of this study was to compare the fatigue resistance of restored teeth with bulk fill composite resin, conventional composite resin with incremental insertion and unprepared sound teeth. Twenty-eight extracted maxillary premolars were selected and divided into 4 groups based on composite resin and insertion technique: control (C), conventional composite resin with incremental insertion (I) and bulk fill composite resin with three (BF3) or single increment (BF1). The restored specimens were submitted to fatigue resistance test with a 5 Hz frequency. An initial application of 5,000 sinusoidal load cycles with a minimum force of 50 N and a maximum force of 200 N was used. Next, were applied stages of 30,000 load cycles with the maximum force increasing gradually: 400, 600, 800, 1000, 1200 and 1400 N. The test was concluded when 185,000 load cycles were achieved or the specimen failed. The fatigue resistance data were recorded for comparison, using the Kaplan-Meier survival curve and analyzed by log-rank test at 0.05 significance. Fractures were classified based on the position of the failure - above or below the cementoenamel junction (CEJ). Statistical analysis of the Kaplan-Meier survival curve and log-rank test showed a significant difference between groups (p=0.001). The fracture analysis demonstrated that only 28.58% of failures were below the CEJ in group C, while for groups I, BF1 and BF3 they were 42.85%, 85.71% and 85.71%, respectively. Teeth restored with composite bulk fill in both techniques present similar fatigue resistance values compared with those restored with a conventional incremental insertion of composite, while the fatigue strength values of unprepared sound teeth were higher. Furthermore, unprepared sound teeth showed a lower percentage of fractures below the CEJ.

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“…Furthermore, the bulk fill technique has been shown to provide lower cusp strain, shrinkage stress and higher fracture resistance (30).…”

Section: Discussionmentioning

confidence: 99%

In Vitro Fatigue Resistance of Teeth Restored With Bulk Fill versus Conventional Composite Resin

et al. 2016

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“…17 To measure the effect of the polymerization shrinkage on surrounding structures, other methods have been used, such as photoelastic analysis, 18 shrinkage force via load cells, 19,20 and cuspal deflection. 8,10,21 Shrinkage stresses have also been analyzed using finite element methods 9,11,12,22 and enamel crack tracking. 10,23 Since different testing methods provide different information about shrinkage stress development, a more complete picture of the complex interactions during the polymerization process is likely obtained by a combination of different tests.…”

Section: Methodology Methods For Measuring Shrinkagementioning

confidence: 99%

“…6,7,8,9 Despite various developments in new restorative materials over the last years, drawbacks related to polymerization shrinkage of composites and resin cements remain a clinical problem. 1,10,11 Typically, dental composites used in restorative procedures exhibit volumetric shrinkage ranging from less than 1% up to 6%, depending on the formulation and curing conditions. 1,10,12 Resin cements exhibit at least similar or even higher polymerization shrinkage values.…”

Section: Introductionmentioning

confidence: 99%

“…1,10,11 Typically, dental composites used in restorative procedures exhibit volumetric shrinkage ranging from less than 1% up to 6%, depending on the formulation and curing conditions. 1,10,12 Resin cements exhibit at least similar or even higher polymerization shrinkage values. 11,13 A consequence of shrinkage stress can be debonding along the restoration/tooth interface or at the restoration margins, resulting in internal and marginal gaps, micro-cracking of either or both the restorative material and tooth structure, marginal stain cuspal movement (Figures 1 and 2).…”

Section: Introductionmentioning

confidence: 99%

“…11,13 A consequence of shrinkage stress can be debonding along the restoration/tooth interface or at the restoration margins, resulting in internal and marginal gaps, micro-cracking of either or both the restorative material and tooth structure, marginal stain cuspal movement (Figures 1 and 2). 6,7,8,9,10,11 When indirect restorations are cemented to a vital tooth, polymerization shrinkage may result in postoperative sensitivity or marginal debonding that contributes to marginal staining, 11 which is often erroneously used as a criterion for replacement of indirect and direct composite restorations ( Figure 2C). …”

Section: Introductionmentioning

confidence: 99%

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Polymerization shrinkage stress of composite resins and resin cements – What do we need to know?

et al. 2017

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Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with postoperative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.

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Composite Resin Bonding

Goldstein¹,

Vargas²

2018

Ronald E. Goldstein's Esthetics in Dentistry

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Mechanical properties, shrinkage stress, cuspal strain and fracture resistance of molars restored with bulk-fill composites and incremental filling technique

Cited by 204 publications

References 38 publications

In Vitro Fatigue Resistance of Teeth Restored With Bulk Fill versus Conventional Composite Resin

In Vitro Fatigue Resistance of Teeth Restored With Bulk Fill versus Conventional Composite Resin

Polymerization shrinkage stress of composite resins and resin cements – What do we need to know?

Composite Resin Bonding

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