The Effect of Thermocycling on Interfacial Bonding Stability of Self‐Etch Adhesives: OCT Study

Abstract

Objective. The aim of this study was to monitor the behavior of interfacial gaps formed under different bonded polymeric restorations before and after thermocycling (TC), using swept-source optical coherence tomography (SS-OCT) and confirming the obtained findings with confocal laser scanning microscopy (CLSM). Materials and Methods. Cylindrical class I cavities were prepared in twenty noncarious human premolar teeth ( 1.5 mm depth × 3.5 mm diameter ) and divided randomly into two groups: TS and SN, according to the adhesive system ( n = 10 ). In the TS group, one-step self-etch adhesive Clearfil Tri-S Bond Plus (Kuraray Noritake Dental, Japan) was used, followed by composite restoration using Estelite Sigma Quick (Tokuyama Dental, Japan). In the SN group, the cavities were restored with the two-step self-etch/composite silorane-based resin restoration system (3M ESPE, USA). All specimens were restored in bulk filling technique and cured in accordance with the manufacturers’ instructions. Both groups were imaged under SS-OCT after 24 h and recorded as controls. Then, each group was subjected to thermal challenge using the TC machine (5–55°C) and B-scans were recorded at different TC intervals (2600, 5200, and 10000). In order to confirm the SS-OCT findings, additional specimens were prepared, scanned, and sectioned for CLSM observation. Results. B-scans demonstrated white clusters at the tooth-resin interface that corresponded to the gap location on CLSM images. The TS group showed significantly less gap formation than the SN group before and after TC ( p < 0.001 ). Conclusions. An optimal composite adaptation can be achieved when the bonded restoration comprises a combination of an adhesive containing 10-MDP monomer and a considerable highly filled composite.

effect of adhesive material and thermocycling on bond strength of intraoral repair materials on adhesive fracture in porcelain fused to metal restoration

“…hydrolytic on the adhesive. 17 Bakhsh et al (2021), in his research also stated that thermocycling can cause a larger gap between the tooth and the restorative material. 16 The absence of thermocycling effect on the 6-MPHA adhesive (Table 2) may be due to the presence of C-P bonds in the 6-MPHA adhesive which causes this type of adhesive to be more water resistant so that it is less affected by thermocycling compared to other types of adhesives.…”

“…4 Metal surfaces also cannot be modified using acid etching. 5 These problems lowered the bond strength of the adhesives in intraoral repair on the metal surfaces.…”

Effect of cigarettes smoke on bonded polymeric restorations: OCT study

“…The refractive index of the tooth and resin composite is approximately 1.5–1.6 [ 11 ], while the refractive indices of air and water are in the range of 1–1.3. It is possible to detect specular reflection in the presence of a significant difference between the bonded media and SS-OCT [ 31 ]. However, silver nitrate was used as a contrasting agent with CP-OCT to intensify the appearance of the interfacial gap in the form of diffuse reflection [ 36 ].…”

“…The type of resin matrix, concentration of monomers, and type of initiator all affect polymerization shrinkage because they determine the polymer structure of the composite resins. Additionally, the amount, type, and size of fillers affect the volumetric shrinkage of composite resins [ 14 , 16 , 31 ]. Owing to the reduced volume of monomers available for the curing reaction, increasing the number of fillers in the resin matrix reduces the overall shrinkage of conventional composite resins.…”

“…Originally, OCT was used in 1991 in-vivo and in-vitro studies to obtain an image of hard and soft dental tissues [ 30 ]. Additionally, it has been utilized in interfacial microgap detection as well as internal restoration defects in 2D (B-scan) and 3D (C-scan) images [ 19 , 31 ]. It can also be used to detect dental caries and enamel cracks [ 29 , 32 ].…”