Setting stresses in composites for two different curing modes

OBJECTIVES: This study aims to evaluate the effect of a minimally invasive mesial-occlusaldistal (mod) preparation on the marginal adaptation of ceramic and composite inlays with the aim of saving sound dental substance. MATERIALS AND METHODS: Class II mod cavities were prepared in 50 extracted human molars and randomly allocated to five groups (n = 10). In all groups, the mesialproximal box margins were located in the dentin, 1 mm below the cementoenamel junction (CEJ), while the distal box margins were 1 mm above the CEJ. In groups A and B, conventional standard preparations with a divergent angle of = 6°were prepared. In groups C, D, and E, minimally invasive standard preparations with a convergent angle of = 10°were prepared. In groups A and D, composite inlays and, in groups B and C, ceramic inlays were fabricated (chairside economical restoration of esthetic ceramics (CEREC)) and adhesively inserted. In group E, a direct composite filling using the incremental technique was placed. Replicas were taken before and after thermomechanical loading (1,200,000 cycles, 50/5°C, max. load 49 N). Marginal integrity (tooth-luting composite, luting composite-inlay) was evaluated by scanning electron microscopy (×200). The percentage of continuous margins in the different locations was compared between and within groups before and after cycling, using ANOVA and Scheffé post hoc test. RESULTS: After the thermomechanical loading, no significant differences were observed between the different groups with respect to the interface of luting composite-inlay. At the interface of toothluting composite for preparations involving the dentin, groups A and B behaved significantly better compared to the control group E, which in turn were not different to groups C and D. CONCLUSION: Composite and ceramic inlays inserted in minimally invasive prepared mod cavities result in margins not different from those of inlays placed in conventional mod preparations. Direct composite filling margins, however, were inferior to those attained by conventional indirect restorations. CLINICAL RELEVANCE: Minimally invasive preparations for mod inlays with undercuts show marginal adaptation equal to that of conventional inlay preparation design. Keywords: Composite inlay, ceramic inlay; minimally-invasive; marginal adaption Declaration of interests:The authors declare they have no conflicts of interest. AbstractObjectives To evaluate the effect of a minimally-invasive mod-preparation on the marginal adaptation of ceramic and composite inlays with the aim of saving sound dental substance. Materials and MethodsClass II mod-cavities were prepared in 50 extracted human molars and randomly allocated to five groups (n=10). In all groups, the mesial-proximal-box-margins were located in dentin, 1 mm below the cementoenamel junction (CEJ), while the distal-boxmargins were 1 mm above the CEJ. In group A and B, conventional standard preparations with a divergent angle of α = 6° were prepared. In Group C, D and E minimally invasive standard preparation...

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“…To minimize the adverse effects of polymerization shrinkage, an incremental placement technique was performed [43,63].…”

Section: Discussionmentioning

confidence: 99%

Marginal adaptation of ceramic and composite inlays in minimally invasive mod cavities

et al. 2013

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“…Several studies have revealed that greater shrinkage stress is generated at adhesive interfaces during the polymerization of light-cured resin composites than that of chemical-cured resin composites [78,79]. This is probably a result of the fact that light-cured resin composites polymerize at a faster rate than chemical-cured resin composites.…”

Section: The Effect Of Light Curing Modesmentioning

confidence: 99%

“…Although polymerization rate reduction may be achieved by decreasing light intensity [79][80][81][82], low light intensity decreases the degree of conversion that is associated with the mechanical properties of the resin composites, and this may result in poor clinical performance of the restorations [83]. Most of the stress reduction is believed to occur during the first 10 s of light activation [78]. Therefore, "soft-start" polymerization modes, such as the two-step mode and the ramping mode have been developed.…”

Section: The Effect Of Light Curing Modesmentioning

confidence: 99%

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations

Kubo

Yokota

et al. 2013

Dental Materials

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Objectives: The incidence of non-carious cervical lesions (NCCLs) has been increasing.The clinical performance of resin composites in NCCLS was previously unsatisfactory due to their non-retentive forms and margins lying on dentin. In order to address this problem, a lot of effort has been put into developing new dentin adhesives and restorative techniques. This article discusses these challenges and the criteria used for evaluating clinical performance as they relate to clinical studies, especially long-term clinical trials. Polymerization contraction, thermal changes and occlusal forces generate debonding stresses at adhesive interfaces.Methods: In laboratory studies, we have investigated how these stresses can be relieved by various restorative techniques and how bond strength and durability can be enhanced. Lesion forms, restorative techniques, adhesives (adhesive strategies, bond strengths, bond durability, and the relationship between enamel and dentin bond strengths) were found to have a complex relationship with microleakage. With regard to some restorative techniques, only several short-term clinical studies were available.

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“…In addition, the stress development is affected by the reaction kinetics as a higher polymerization rate is accompanied by high polymerization stress [15,16]. The material plastic deformation is time dependent phenomenon in which the material needs time to flow to accommodate the contraction stresses before the development of the modulus of elasticity [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Polymerization shrinkage kinetics and shrinkage-stress in dental resin-composites

2016

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Shrinkage-strainShrinkage-stress Strain rate Modulus of elasticity Bulk-fill a b s t r a c tObjectives. To investigate a set of resin-composites and the effect of their composition on polymerization shrinkage strain and strain kinetics, shrinkage stress and the apparent elastic modulus.Methods. Eighteen commercially available resin-composites were investigated. Three specimens (n = 3) were made per material and light-cured with an LED unit (1200 mW/cm 2 ) for 20 s. The bonded-disk method was used to measure the shrinkage strain and Bioman shrinkage stress instrument was used to measure shrinkage stress. The shrinkage strain kinetics at 23 • C was monitored for 60 min. Maximum strain and stress was evaluated at 60 min. The shrinkage strain rate was calculated using numerical differentiation. Significance. The nature of the monomer system determines the amount of the bulk contraction that occurs during polymerization and the resultant stress. Higher values of shrinkage strain and stress were demonstrated by the investigated flowable materials. The bulk-fill materials showed comparable result when compared to the traditional resin-composites.

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Setting stresses in composites for two different curing modes

Cited by 198 publications

References 6 publications

Marginal adaptation of ceramic and composite inlays in minimally invasive mod cavities

Marginal adaptation of ceramic and composite inlays in minimally invasive mod cavities

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations

Polymerization shrinkage kinetics and shrinkage-stress in dental resin-composites

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