Evaluation of polymerization shrinkage of bulk-fill resin composites using microcomputed tomography

Abstract

OBJECTIVES This study evaluated the influence of cavity depth on polymerization shrinkage of bulk-fill resin composites with and without adhesive resin. MATERIALS AND METHODS Standardized box-shaped cavities (width, 4 mm; length, 5 mm, depth, 2 mm or 4 mm) were made on occlusal surfaces of extracted human third molars (N = 60). The teeth were assigned to 3 groups to receive bulk-fill resin composites (low-viscosity bulk-fill, SDR; high-viscosity bulk-fill; Filtek Bulk-Fill-FB; and TetricEvo Ceram Bulk-Fill-TB) in the prepared cavities with and without adhesive resin (Clearfil S3 Bond). Each specimen (n = 5 per group) was scanned twice using microcomputed tomography (micro-CT): once after application of the resin composite to the cavity prior to polymerisation and once after polymerisation. The shrinkage of volumetric loss (%) was measured using micro-CT. Data were analysed using Kruskal-Wallis and Mann-Whitney U tests (alpha = 0.05). RESULTS The material type (p < 0.05), application of adhesive resin (p < 0.05) and cavity depth (p < 0.05) significantly affected the shrinkage values. The interaction terms were also significant (p < 0.05). All the bulk-fill resin composites tested showed significantly less shrinkage when applied in cavities with adhesive resin (0.94-2.55) compared with those without (2.01-3.45) (p < 0.05) and presented significantly more shrinkage after polymerisation (p < 0.05). At a 2-mm cavity depth without (2 mm, 2.28; 4 mm, 2.41) and with adhesive (2 mm, 0.94; 4 mm, 1.67), significantly less shrinkage was observed with FB compared with SDR and TB (p < 0.05). At a 4-mm cavity depth without (3.14) and with adhesive (2.55), SDR showed significantly higher shrinkage compared with FB and TB (p < 0.05). CONCLUSIONS The bulk-fill composites tested presented less shrinkage when used in conjunction with adhesive resin application on dentin. Overall, the low-viscosity bulk-fill resin SDR showed more shrinkage compared with high-viscosity resins tested. CLINICAL REL-EVANCE Low-or high-viscosity bulk-fill resin composites should be applied on dentin after application of adhesive resin to decrease shrinkage.

Effect of access cavity design on gaps and void formation in resin composite restorations following root canal treatment on extracted teeth

“…The superior translucency of bulk fill composites allows better light dissipation through the material (Furness et al 2014, Veloso et al 2018. Though bulk fill composite has low polymerization shrinkage, Ersen et al (2020) observed that cavity depth affects polymerization shrinkage. In the present study, the pulp chambers were standardized between groups.…”

“…In the present study, the pulp chambers were standardized between groups. All pulp chambers had height values less than 4 mm and were statistically similar to allow effective composite polymerization and thus similar polymerization shrinkage (Furness et al 2014, Veloso et al 2018, Ersen et al 2020. All stages of root canal treatment and coronal restoration were performed on a dental mannequin, simulating clinical treatment, in order to mimic clinical conditions.…”

Effects of curing modes on depth of cure and microtensile bond strength of bulk fill composites to dentin

“…However, most recent studies report data related to the former formulation, compatible with the bulk fill composites used in our study. 5,6,39,40 In addition, our study cannot expand on further discussion related to the potential interference of the two material composition, since they were not directly compared.…”

“… 3 , 4 Although these modifications vary, most manufacturers aim for a more translucent material with enhanced curing capability through filler modifications, 2 , 3 incorporation of high molecular weight monomers, and/or addition of new alternative photoinitiators. 2 , 5 - 8 Several commercially available bulk-fill materials have increased filler size or decreased filler content to minimize the scattering of light, thus encouraging light transmittance. 2 , 7 Moreover, modifications to monomers and photoinitiator targets improved optical properties, reduced polymerization shrinkage, and increased DOC.…”

Multifunctional Bioactive Resin for Dental Restorative Materials

“…In addition, Nikolaidis et al reported the reinforcement of dental nanocomposite resins with different organo-modified montmorillonite nanofillers [13]. Dental materials still suffer several significant problems, such as polymerization shrinkage at the tooth-composite interface, which can lead to micro-leakage, and secondary caries [14][15][16][17][18]. In 2007, Bernardo et al [19] evaluated 1748 restorations and revealed that the use of composites increased the risk of secondary caries by about 3.5 times as compared with the use of amalgams.…”