Effect of light absence or attenuation on biaxial flexural strength of dual‐polymerized resin cements after short‐ and long‐term storage

Abstract

Objective To evaluate whether biaxial flexural strength (BFS) of dual resin cements is affected by light absence or attenuation, storage time, or cements' chemical nature. Materials and methods One hundred and twenty disk‐shaped specimens were made from each cement (non‐self‐adhesive cement and self‐adhesive cement) using Teflon molds on a controlled temperature surface (35°C). Specimens were polymerized as follows (N = 30): self‐cured, directly light‐cured, light‐cured at a distance of 6 mm between the light tip and the specimen, and through a 6‐mm thick composite resin barrier (indirectly light‐cured). Each group was divided (N = 10) for storage purposes (15 minutes, 24 hours, and 6 months). Specimens were placed into a biaxial‐flexure jig and a vertical load was applied until failure. The BFS values were subjected to generalized linear models statistical analysis and Weibull distributions (α = 0.05). Results After 15 minutes aging, neither material achieved enough polymerization to perform the BFS test when polymerized using the self‐curing mode. The self‐adhesive product demonstrated much lower variation in strength with storage time than did the non‐self‐curing cement. Conclusions Attenuated/light‐curing reduced BFS values only for 15‐minutes storage period for both materials. Flexural strength of the self‐adhesive cement was less affected by light absence/attenuation and storage time. Clinical significance Biaxial flexural strength of a self‐adhesive resin cement is less sensitive to variation in light application and storage time than is a non‐self‐adhesive cement.

Dental Resin-Based Luting Materials—Review

“…According to the polymerization reaction mechanism, resin cements can be classified into self-cure, light-cure and dual-cure categories (Table 2) [5,45,63].…”

“…An ample body of evidence also shows that the light beam weakens as it passes through the restoration material, making it difficult to achieve the intensity required for the polymerization of resin cement in deep and inaccessible parts of the tooth preparation. Consequently, a less successful and efficient polymerization of the resin cement is expected, which may lead to increased hydrolytic degradation, microleakage and the presence of secondary caries [5]. The aforementioned challenges can be mitigated by combining chemical and light-induced polymerization [13], which requires a dual polymerizing catalyst [65,66].…”

“…Studies have demonstrated their good mechanical properties, reliable adhesive bond with the tooth structure and restoration, easy handling and satisfactory aesthetics [3][4][5]. Adhesive cements are considered an improved version of luting materials due to their superior adhesion to the tooth structure [2].…”

The effect of amine-free initiator system and polymerization type on long-term color stability of resin cements: an in-vitro study

“…However, inadequate polymerization of camphorinon causes the discoloration to yellow shades. Some resin cements were produced photo-initiator tertiary amine free to prevent discoloration [ 12 , 13 ]. It has been reported that new resin cements without tertiary amine show much less discoloration.…”

Influence of the resin‐coating technique on the bonding performance of self‐adhesive resin cements in single‐visit computer‐aided design/computer‐aided manufacturing resin restorations

“…12 Dual-cured resin cements that are prepared by both chemically activated and photoactivated mechanisms are frequently used for cementation of indirect restorations 13,14 because light attenuation occurs beneath the restorative materials, especially in deep areas of the preparation. 15 For the sake of improving the handling properties and reducing the procedure time, self-adhesive resin cements that eliminate pretreatment of the tooth structure have been widely used. 16 Some dualcured self-adhesive resin cements demand surface treatment, including both sandblasting and silanization on CAD/CAM resin blocks.…”