Adhesiveness of bulk-fill composite resin in permanent molars submitted to Streptococcus mutans biofilm

Abstract

The aim of the present study was to evaluate the microtensile bond strength and the microleakage of a bulk-fill composite resin compared with a conventional incremental composite resin, in permanent molars and under cariogenic challenge using a Streptococcus mutans model. Permanent human third molars (n = 60) with an occlusal cavity of 5x3x2 mm were randomly allocated into four subgroups of restorative treatments: conventional composite resin with (n = 15) and without (n = 15) cariogenic challenge (Z350-E and Z350-C experimental and control groups, respectively), and bulk-fill composite resin with (n = 15) and without (n = 15) cariogenic challenge (Bulk Fill-E and Bulk Fill-C, respectively). Ten specimens from each subgroup were submitted to microtensile strength, and 5, to microleakage. The cariogenic challenge was conducted using the Streptococcus mutans strain (ATCC) for 7 days. The stickers obtained (1 x 1 x 2 mm) were submitted to a microtensile strength test, followed by classification of the fracture mode. Microleakage was performed using a scoring system. The data were analyzed by Kruskal-Wallis and Mann-Whitney tests (p < 0.05). Filtek Z350 XT resin presented higher microtensile bond strength than Bulk Fill resin without (19.02 ± 4.90 and 8.76 ± 3.94MPa, respectively; p < 0.001) and with cariogenic challenge (22.69 ± 7.86 and 13.31 ± 3.38MPa, respectively; p < 0.02). Z350-C and Bulk Fill-C resins presented a higher prevalence of mixed fractures (23 and 14%, respectively) in the specimens submitted to cariogenic challenge than those of the control groups, whereas microleakage was similar (p = 0.85). The conventional composite resin had higher microtensile bond strength than the bulk-fill resin, but both resin types had similar adhesion quality and microfiltration scores.

Evaluation of heated air jet on pulp chamber temperature at different steps of the restorative protocol

“…Fortunately, several studies have been insistent in seeking to improve the adhesion capacity and the mechanical properties of adhesive restorations (Ogura, et al, 2012;Fidalgo, et al, 2019;Zhou, et al, 2019). As previously mentioned, volatilization with heated air has led to an increase in mechanical and physical properties (Alexandre, et al, 2008;Klein-Júnior, et al, 2008;Reis, et al, 2009;Reis, et al, 2010;Ogura, et al, 2012;Ferreira-Barbosa, et al, 2020).…”

Effect of Polywave and Monowave Light Curing Units on the Microtensile Bond Strength and Failure Types of Different Bulk-Fill Resin Composites: An in vitro Study

“…3 For this reason, new products such as bulk-fill resin composites have been introduced in the market. 1 , 2 , 4 …”

“…3 For this reason, new products such as bulk-fill resin composites have been introduced in the market. 1,2,4 Bulk-fill resin composites have been developed to reduce operating times and simplify restorative techniques because they can be placed in the cavity preparation and light-cured in a single 4 to 5 mm increment. [4][5][6][7][8] They also contain new and more translucent photoinitiators that allow light transmission to deeper layers.…”

“…1,2,4 Bulk-fill resin composites have been developed to reduce operating times and simplify restorative techniques because they can be placed in the cavity preparation and light-cured in a single 4 to 5 mm increment. [4][5][6][7][8] They also contain new and more translucent photoinitiators that allow light transmission to deeper layers. [5][6][7][8][9] Compared to conventional resins, these present reduced polymerization stress and high reactivity to photopolymerization due to changes in the composition and concentration of the filler and/or the organic matrix and also to the presence of stress inhibitors.…”

“…11,12 That is why, polymerization must be taken into account in clinical practice, since, if photopolymerization does not penetrate to the full depth of the resin, it could compromise its mechanical properties and the integrity of the interface, influencing the durability of the restoration. 1,2,4 Microtensile strength is one of the least investigated mechanical properties in these composites. 8 The microtensile bond strength test (µTBS) has some advantages, such as the ability to investigate bond strength in small areas below 1 mm 2 .…”