The Effect of Radiotherapy on the Marginal Adaptation of Class II Direct Resin Composite Restorations: A Micro-computed Tomography Analysis

Abstract

SUMMARY This laboratory study was designed to evaluate the marginal adaptation of Class II mesio-occluso-distal (MOD) restorations at the cervical region with micro-computed tomography (micro-CT). Two groups of restorations were compared: 1) those that had been exposed to radiotherapy before restoration was performed using a universal adhesive in etch-and-rinse and self-etch modes; and 2) those that had previously been restored using a universal adhesive in etch-and-rinse and self-etch modes and had subsequently undergone radiotherapy. Sixty intact human molars were randomly divided into groups according to irradiation status: no radiotherapy (control group); radiotherapy followed by restoration (radiotherapy-first group); and restoration followed by radiotherapy (restoration-first group). These three groups were then subdivided into two groups each on the basis of adhesive application type (etch-and-rinse and self-etch modes), for a total of six groups (n=10/group). Standardized Class II MOD cavities were prepared. A universal adhesive (Clearfil Universal Bond Quick, Kuraray, Okayama, Japan) was applied. The teeth were restored with resin composite (Estelite Posterior Quick, Tokuyama, Tokyo, Japan). The radiotherapy protocol was conducted with 60 gray (Gy) at 2 Gy/day, five days a week for six weeks. Adhesive defects were analyzed in distal and mesial views and evaluated with micro-CT (SkyScan 1174v2, Kontich, Antwerp, Belgium) on the basis of the volume of black spaces between the cavity walls and the restorative materials (mm3). The data were analyzed using the Kruskal-Wallis, Mann Whitney U and Wilcoxon tests (p<0.05). The radiotherapy protocol did not affect the marginal adaptation of the universal adhesive at the cervical regions. Regarding the application modes, for the radiotherapy-first group, the self-etch mode caused significantly higher adhesive defects than the etch-and-rinse mode at the dentin margin. For the no-radiotherapy group, the adhesive defects at the dentin margin were significantly higher than at the enamel margin with the application of the etch-and-rinse mode.

Impact of Irradiation on the Adhesive Performance of Resin-Based Dental Biomaterials: A Systematic Review of Laboratory Studies

“…The three included studies that assessed the marginal adaptation of direct resin-based composite restorations reported conflicting findings. Irradiation did not significantly affect the marginal adaptation of direct resin-based composite restorations bonded with a universal adhesive in one investigation [ 18 ]. In specimens subjected to irradiation before the restorative procedure, more marginal defects were observed in restorations bonded with a universal adhesive applied in self-etch mode compared with the same adhesive in etch-and-rinse mode [ 18 ].…”

“…Irradiation did not significantly affect the marginal adaptation of direct resin-based composite restorations bonded with a universal adhesive in one investigation [ 18 ]. In specimens subjected to irradiation before the restorative procedure, more marginal defects were observed in restorations bonded with a universal adhesive applied in self-etch mode compared with the same adhesive in etch-and-rinse mode [ 18 ]. One study found that the marginal gap of direct resin-based composite restorations was higher in irradiated than unirradiated specimens [ 40 ].…”

“…However, one study found no difference in leakage between irradiated and unirradiated teeth and reported better results with a self-etch adhesive than an etch-and-rinse adhesive at cervical margins of restorations [ 49 ]. Additionally, one study that evaluated marginal adaptation of irradiated teeth using X-ray microtomography found no difference in adaptation but more dentin margin defects in specimens bonded with a self-etch adhesive [ 18 ].…”

“…Regardless of the surface conditioning, a high degree of microleakage was found in specimens with irradiation. Oglakci et al, 2022b [ 18 ] Human molars 60 in total (six subgroups, each with 10 specimens) MOD restorations evaluated at the enamel and dentin margins Molar teeth with MOD restorations 3 main groups (no irradiation; irradiation before restoration; irradiation after restoration); 2 subgroups (universal adhesive applied in E&R or SE mode) 60 Gy at 2 Gy/day, 5 days a week for 6 weeks Universal adhesive (Clearfil Universal Bond Quick, Kuraray, Okayama, Japan); RBC (Estelite Posterior Quick, Tokuyama Dental, Tokyo, Japan) Analysis of marginal adaptation done using X-ray microtomography Irradiation did not affect the marginal adaptation of the universal adhesive at the cervical regions. In specimens subjected to irradiation before the restorative procedure, more adhesive defects at the dentin margin were observed in the SE group than in the E&R group.…”

“…Owing to the high incidence of radiation-related caries, restorative interventions are often necessary [ 10 ]. In recent years, there has been an increase in studies evaluating the impact of irradiation on enamel, dentin, and the adhesive performance dental biomaterials [ 12 , 18 ].…”