Efficacy of chlorhexidine and rosmarinic acid to prevent resin/dentine interface degradation

Abstract

The objectives of this study were to evaluate the bond strength and the nanoleakage of resin composite restorations at the resin/dentine interface.Flat occlusal dentine surfaces were prepared from extracted premolars, etched with phosphoric acid and treated with either 2% chlorhexidine digluconate (CHX) orµM100rosmarinic acid solution (RMA) or were not treated. The specimens were then restored with either three-step (OptiBond ® FL) or two-step (OptiBond ® Solo Plus TM ) etch-and-rinse adhesives and a resin composite. The restored teeth were prepared as hourglass specimens and further divided according to the storage media (pure mineral oil or artificial saliva) and storage time (24 hours, 3 months, 6 months, and 1 year). The storage specimens were subjected to a micro-tensile bond strength test and a nanoleakage observation.The bond strength to dentine of both adhesives without dentine surface treatment decreased after storage in artificial saliva for 3 months to 1 year (p<0.05) but did not decrease after storage in pure mineral oil. Dentine surface treatment with either CHX or RMA, under either of the adhesives, was able to postpone the degradation of the bond strength by 3 months (p<0.05). Nanoleakage within the resin-dentine interface bonded without dentine surface treatment increased over time when it was stored in artificial saliva but not in pure mineral oil. Dentine surface treatment with either CHX or RMA prevented nanoleakage only up to 3 months of storage. These findings suggest that effectiveness of MMP-inhibitors in preserving the integrity of the resin-dentine bond is time dependent.

Evaluation of Matrix Metalloproteinases Biodegradation Inhibition Protocols on Resin-Dentine Interfacial Characteristics (An In Vitro Comparative Study)

“…Samples were sectioned into 1 mm thick slabs using isomet perpendicular to adhesive interface to investigate nanoleakage. The bonded slabs (16/ group) were coated with two layers of nail varnish applied up to 1 mm from the bonded interface, then immersed in an 50% ammoniacal silver nitrate solution in total darkness for 24 h and prepared according to the protocol previously described by Tay et al (9) . They were then removed, properly rinsed under running tap water and immersed in photo developing solution for 8 h under a fluorescent light to reduce the penetrated silver ions into metallic silver grains (9) .…”

“…Restored teeth were sectioned longitudinally to obtain resin-dentine beams of 1 mm×1 mm. In order to facilitate identification of beam location in restored teeth whether peripheral or central, the surfaces of composite restorations were painted with permanent ink so that the end of central beams would have a different color from peripheral ones (9) . A gripping attachment was designed specially to hold acrylic blocks firmly with mounted teeth parallel to the sectioning direction, so the relation between the cutting disc and the occlusal surface was maintained perpendicular.…”

“…Resultant beams were 0.9±0.1 mm in thickness and 5.5±1 mm in length and beams were stored in a tight-seal plastic cone labeled according to subgroup and tooth of origin in distilled water at room temperature. After 24h, half of the specimens (n=8 teeth) were thermocycled as mentioned before (9) .…”

“…Geraldeli's jig was used to mount beams onto the universal testing machine (Instron universal testing machine model 3345 England). Then the jig was mounted into the universal testing machine with a load cell of 500 N (9) . Tensile load was applied, at a crosshead speed of 0.5 mm/min, until bonding failure of the specimen occurred.…”