Effects of cuspal compliance and radiant emittance of LED light on the cuspal deflection of replicated tooth cavity

Abstract

The aim was to investigate effects of compliance and radiant emittance on cuspal deflection. A mesio-occluso-distal cavity was replicated using a flowable composite and steel rods with different diameters. To investigate the effect of cuspal compliance on deflection, the replicated tooth and extracted human tooth cavities were bulk-filled with a micro-hybrid composite. The replicated cavities with 2.0-mm-diameter steel rods were restored with bulk-filling of the micro-hybrid or a nano bulk-fill composite and photocured with four protocols. The cuspal deflection was the highest in the replicated tooth without steel rod, followed by with 1.0-, 1.5-, and 2.0-mm steel rods, and significantly lower in the human tooth. Cuspal deflections showed no significant differences among lightcuring protocols, and that in the micro-hybrid composite were higher than the nano bulk-fill composite. To reduce cuspal deflection of a high compliance cavity, selecting the proper composite based on physical properties is more important than light-curing protocol.

Effects of wall compliance and light-curing protocol on wall deflection of simulated cavities in bulk-fill composite restoration

“…In addition, cuspal compliance of class II MOD tooth cavities has been measured in the range of 0.5–3.32 μm/N depending on size of the cavity. 2 , 25 Therefore, aluminum molds can simulate various clinical situations and allow investigation of wall deflections with minimal variations among specimens. In the present study, mold wall compliance decreased with increasing mold wall thickness and was comparable to findings from a previous study.…”

“… 24 However, in composite tooth cavities with embedding steel rods into the center of the buccal and palatal cusp, which was replicated from an MOD cavity on an artificial model tooth, no significant differences in cuspal deflection were observed when changing the radiant emittance of the PWM-LED light due to the high compliance of cavity walls. 25 …”

Effect of radiant emittance of an LED curing light on the cuspal deflection of a simulated tooth cavity in bulk-fill composite restoration: A novel simulation method

“…When cuspal compliance is very large, some of the polymerization shrinkage stress generated at an adhesive interface can be relieved by cusp deflection; conversely, when cuspal compliance is relatively small, enamel microcracking and restoration detachment may occur because of an accumulation of stress at the interface. In previous studies, cuspal deflection was found to change with variation in cuspal compliance 1,[3][4][5][6] . To obtain clinically relevant data on cuspal deflection in vitro, it is important to conduct studies under conditions that simulate natural human teeth.…”

“…Another simulation model has been applied to address the aforementioned limitations and replicate a prepared tooth cavity using a composite tooth prepared with steel rods and a flowable composite 5) . However, despite the attempt to reinforce the flowable composite with low elastic modulus (3.40-8.62 GPa) 3,[24][25][26][27] through the use of embedded steel rods with an elastic modulus of approximately 200 GPa 28) , the cuspal compliance of the replicated composite tooth was higher than that of human teeth 5) .…”

A Review on Current Trends of Polymers in Orthodontics: BPA-Free and Smart Materials

“…A comparison was also drawn between the newly synthesized monomers. U-(bis-GMA)-Mod displayed lower polymerization shrinkage and stress, lower water sorption and water solubility, and a higher value refractive index than U-(GDMA)-Mod [ 38 , 47 ]. However, U-(GDMA)-Mod had a greater resistance than U-(bis-GMA)-Mod to leaching in organic solvents, and both monomers were free of BPA.…”