Morphological Aspects of the Resin-Dentin Interdiffusion Zone with Different Dentin Adhesive Systems

Abstract

Cross-sections of resin-dentin interfaces were etched with an argon-ion beam to make their substructure detectable by scanning electron microscopy. The dentin adhesive systems were categorized morphologically into three groups, and an attempt was made to clarify their adhesive mechanism. The first group of products removed the smear layer. The argon-ion bombardment clearly disclosed a hybrid or resin-impregnated dentin layer. It is hypothesized that conditioning with acidic or chelating agents demineralized the dentin surface-layer to a certain depth, leaving behind a collagen-rich mesh-work. Hydrophilic monomers are then believed to alter this collagen-fiber arrangement in a way that facilitates penetration of the adhesive resin, resulting in a mechanical, intermingled link between collagen and the adhesive resin. The second group preserved the smear layer. In this case, the dentinal tubules were obliterated with globular particles at their orifices and remained patent underneath these smear plugs. This type of adhesive system aims at the incorporation of the smear layer into the hydrophilic monomers, which have an affinity for the organic and/or inorganic components of the underlying dentin. Finally, a third, small group only partly dissolved the smear layer, creating a thin resin-impregnated dentin layer and a resin-impregnated smear plug. This study clearly showed that the application of recent adhesive systems induced structural changes in the dentin surface morphology, creating a retentive interface, called the inter-diffusion zone, between the deep, untouched dentin layers and the composite filling material. This resin-dentin interdiffusion zone offers bonding sites for copolymerization with the resin composite and, concurrently, might have protective potential for the pulp tissues.

Animal and human dentin microstructure and elemental composition

“…Muylle research group [3], on the other hand, etched equine incisor dentin with 20% phosphoric acid. The application of phosphoric acid on dentin surface also results in smear layer removal, but it also causes demineralization of the PTD and ITD [37]. In this study no irrigation agents or acids were used and this may be the reason for smaller DT diameters established than reported in previous studies.…”

“…As also dentin sample anatomical locations in a tooth [10,32] and specimen preparation procedures [6,33,36,37] may influence results notably, all these variables were controlled as much as possible in this study to ascertain that differences/similarities were truly the result of interspecies variations. Ultrasonic bath of 0.27 M EDTA for 5 minutes was reported in dentin samples prepared by Schilke [33] and Robb [6] research groups.…”

Rewetting effect of water-based primer on the air-dried dentin

“…최근의 상아질 접착개념 중의 하나는 표층 상아질의 도말 층과 무기물을 제거함으로써 상아세관을 개방시켜 충분한 세관간 미세공극을 형성하여 노출된 교원질망으로 레진 단 량체를 침투시키고자 하는데 있다 [1][2][3] . 이러한 개념은 1982 년 Nakabayashi가'혼성층' 이라는 용어로 처음 설명하였 다 4) .…”

Marginal and internal adaptation of class II restorations after immediate or delayed composite placement

“…Actually, the inhibitory effect of oxygen is known to affect resin polymerization to a depth of 100 mm or more and to create a layer of totally non-polymerized resin of about 15 mm [45]. As resin penetrates the demineralized dentin to a depth of only 0 -10 mm and considering the extremely thin resin coating normally persisting on the dentin surface [46,47], a complete resin polymerization within the adhesive interface prior to composite placement is unlikely. As a consequence, the collagen network might be disturbed by composite placement, which generally results in a higher proportion of adhesive failures at the hybrid layer-bonding resin interface [48,62].…”