A novel dentin bonding scheme based on extrafibrillar demineralization combined with covalent adhesion using a dry-bonding technique

Abstract

Dentin bonding is a dynamic process that involves the penetration of adhesive resin monomers into the extrafibrillar and intrafibrillar demineralized collagen matrix using a wet-bonding technique. However, adhesive resin monomers lack the capacity to infiltrate the intrafibrillar space, and the excess water that is introduced by the wet-bonding technique remains at the bonding interface. This imperfectly bonded interface is inclined to hydrolytic degradation, severely jeopardizing the longevity of bonded clinical restorations. The present study introduces a dentin bonding scheme based on a dry-bonding technique, combined with the use of extrafibrillar demineralization and a collagen-reactive monomer (CRM)-based adhesive (CBA). Selective extrafibrillar demineralization was achieved using 1-wt% high-molecular weight (MW) carboxymethyl chitosan (CMCS) within a clinically acceptable timeframe to create a less aggressive bonding substance for dentin bonding due to its selectively extrafibrillar demineralization capacity. CMCS demineralization decreased the activation of in situ collagenase, improved the shrinking resistance of demineralized collagen, and thus provided stronger and more durable bonding than traditional phosphoric acid etching. The new dentin bonding scheme that contained CMCS and CBA and used a dry-bonding technique achieved an encouraging dentin bonding strength and durability with low technical sensitivity. This bonding scheme can be used to improve the stability of the resin-dentin interface and foster the longevity of bonded clinical restorations.

Mussel-inspired polymer with catechol and cationic Lys functionalities for dentin wet bonding

“…Four 10 ​× ​1 ​× ​1-mm sticks perpendicular to the long axis of each tooth were used in the bond strength test as previously described [ 16 ]. The microtensile bond strength (μTBS) value of each specimen was measured using a microtensile testing machine (EZ-TEST 500 ​N, Shimadzu Co.) at a crosshead speed of 1 ​mm/min.…”

“…The bonding interface was observed using field-emission scanning electron microscopy (FE-SEM, S-4800, Hitachi, Tokyo, Japan) as previously described [ 16 ]. Briefly, 1-mm-thick specimens perpendicular to the bonding interface were polished with silicon carbide paper, etched with 37% phosphoric acid, immersed in 5% sodium hypochlorite, ultrasonic-irrigated, fixed, dehydrated, sputter-coated with gold, and examined using FE-SEM.…”

“…The nanoleakage level of bonding interface was evaluated using FE-SEM as previously described [ 16 ]. Four 4 ​× ​1 ​× ​1-mm slices along the long axis from each tooth were coated with nail varnish, leaving an uncoated region of approximately 1 ​mm around the bonding interface.…”

“…Similar to mussel adhesion, dentin bonding occurs in wet conditions in which water from saliva, dentinal tubules, rinse fluids, and dental equipment is in contact with the dentin substrate. However, unlike mussel bonding, long-lasting dentin bonding, to which water is considered the main barrier, is difficult to achieve [ [14] , [15] , [16] ]. In general, dentin bonding is a process in which exogenous resins penetrate the demineralized collagen network [ 12 , 13 ].…”

“…This residual moisture in the cured bonding interface can induce a series of degradation processes and undermine the durability of the bonding interface [ 17 ]. Recently, chemical dehydration protocols and extrafibrillar demineralization techniques have been introduced to address water-associated issues during dentin bonding; however, limitations still exist [ [16] , [17] , [18] , [19] , [20] , [21] ].…”