Gel Phase Formation at Resin-modified Glass-ionomer/Tooth Interfaces

Abstract

Ionic bonding between polyalkenoic acid and hydroxyapatite may explain the excellent bonding retention of glass-ionomers in clinical trials. We have here investigated the extent to which the self-adhesiveness of resin-modified glass-ionomers (RMGIs) can be attributed to this chemical bonding capacity. Therefore, the interaction of 3 RMGIs with tooth substrates was comprehensively characterized, with electron and atomic force microscopy correlated with x-ray photoelectron spectroscopy (XPS). Interfacial ultrastructural analysis for 2 RMGIs disclosed a shallow hybridization of hydroxyapatite-coated collagen, on which a submicron gel phase was deposited through reaction of the polyalkenoic acid with calcium extracted from the dentin surface. One RMGI, however, bonded to dentin without hybrid layer or gel phase formation. XPS indicated that polycarboxylic acids included in the RMGIs electrostatically interacted with hydroxyapatite. We conclude that the self-adhesiveness of RMGIs should be attributed to ionic bonding to hydroxyapatite around collagen, and to micro-mechanical interlocking for those RMGIs that additionally hybridize dentin.

Effect of Substrate Age and Adhesive Composition on Dentin Bonding

“…The selfadhesive bonding mechanism of these materials is twofold: (1) the ionic bonding to hydroxyapatite around collagen, as in conventional GIC, and (2) the micromechanical interlocking for those resinmodified GIC that additionally hybridize dentin. 22 For Vitrebond, the first material to contain the copolymer used in EB and SB, there is no evidence of the second mechanism (ie, hybridization or gel phase deposition). 22 Since the bonding associated with Vitrebond is stable and there is an tight contact between this material and dentin, chemical interaction is the primary bonding mechanism for this resin-modified GIC.…”

“…22 For Vitrebond, the first material to contain the copolymer used in EB and SB, there is no evidence of the second mechanism (ie, hybridization or gel phase deposition). 22 Since the bonding associated with Vitrebond is stable and there is an tight contact between this material and dentin, chemical interaction is the primary bonding mechanism for this resin-modified GIC. 22 A five-year clinical study 23 with a CP-containing resin-modified GIC material reported excellent retention rates.…”

“…EB resulted in statistically similar mean lTBS compared to EBnoCP for all age groups: p = 0.538 for (,21); p = 0.974 for (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40); and p = 0.909 for (.40). SB resulted in statistically higher mean lTBS than SBnoCP for all age groups [p,0.009 for (,21); p,0.028 for (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40); and p,0.041 for (.40)]. MP, the control group, resulted in statistically lower mean lTBS when applied to the oldest age group (.40) compared to the youngest age group (,21), at p , 0.04.…”

“…Materials and Methods: Sixty extracted caries-free human teeth were assigned to the appropriate age group: less than 21 years of age (,21), 21-40 years of age (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40), and greater than 40 years of age (.40). For each age group, specimens were randomly divided into five dentin adhesives: (1) Adper Easy Bond (EB, 3M ESPE), a one-step self-etch adhesive; (2) Experimental Adper Easy Bond without the Vitrebond Co-polymer (CP) (EBnoCP, 3M ESPE); (3) Adper Single Bond Plus (SB, 3M ESPE), a two-step etch&rinse adhesive; (4) Experimental Adper Single Bond Plus without CP (SBnoCP, 3M ESPE); and (5) Adper Scotchbond Multi-Purpose (MP, 3M ESPE), a threestep etch&rinse adhesive, as the control group.…”

Bonding efficiency and durability: current possibilities

“…micro-mechanical and chemical adhesion) closely resembles that of glass-ionomers. 62 The additional chemical bonding of mild self-etch adhesives and glass-ionomers is supposed to be beneficial in terms of bonding durability. 18,20 However, the ability to chemically bond to HAp is not sufficient on its own.…”