A TEM Study of Two Water-based Adhesive Systems Bonded to Dry and Wet Dentin

Abstract

To keep the exposed collagen scaffold penetrable to resin, it has been recommended that the conditioned dentin surface be maintained in a visibly moist condition, a clinical technique commonly referred to as wet bonding. In this study, resin-dentin interfaces produced with two water-based adhesive systems--OptiBond (OPTI, Kerr) and Scotchbond Multi-Purpose (SBMP, 3M)--were compared by transmission electron microscopy, following the application of either a dry- or a wet-bonding technique. The hypothesis advanced was that the ultramorphology of the hybrid layer would differ depending on which bonding method was applied. A morphologically well-organized hybrid layer of collagen fibrils intermingled with resin in tiny interfibrillar channels was consistently formed by the OPTI system. The SBMP system was found to produce a hybrid layer with a more variable ultrastructure, less distinctly outlined collagen fibrils, and a characteristic electron-dense phase located at its surface. No major differences in hybrid layer ultrastructure were observed when the two adhesive systems investigated were bonded to either dry or wet dentin. When the adhesives were dry-bonded, no ultrastructural evidence of collapsed demineralized collagen, incompletely or not at all infiltrated by resin, could be detected. In addition, when the two adhesives were bonded to wet dentin, no signs of overwetting phenomena, that would have indicated that water was ineffectively removed, were apparent. It has been hypothesized that the amount of water provided with the hydrophilic primer solution of either of the two adhesive systems investigated suffices to re-hydrate and re-expand the gently air-dried and collapsed collagen network. Further research should be directed to determine whether this hypothesized self-rewetting effect can be extrapolated to other adhesive systems that provide water-based primers.

Effects of different types of adhesive systems on the microleakage of compomer restorations in Class V cavities prepared by Er,Cr:YSGG laser in primary teeth

“…Etch-and-rinse adhesives that contain acetone require a wet bonding technique 17,36,41) . For adhesives that contain ethanol and water, a dry bonding technique is key to delivering good bonding performance 17,38,42) . The wet bonding technique is technique-sensitive and constantly begs the question "how wet is wet?".…”

“…The wet bonding technique is technique-sensitive and constantly begs the question "how wet is wet?". Therefore, the wet bonding technique has a shortcoming of overwetting the etched dentin surface if water is not effectively removed 42) . Application mistakes could then adversely affect bond strength and marginal adaptation, thus accounting for the higher microleakage of Prime&Bond NT than Adper Single Bond 2 and Scotchbond Multi-Purpose Plus.…”

Influência do Grau de Umidade da Dentina Decídua na Infiltração Marginal da Interface Formada com Três Sistemas Adesivos

“…A pobre atuação deste sistema adesivo em dentina seca foi atribuída a uma proporção inadequada de água e etanol neste produto, podendo não ser suficiente para permitir a reexpansão das fibras colágenas desidratadas 20 . Embora desfavoráveis para o Single Bond, os resultados do presente estudo corroboram outros que afirmam que primers à base de água apresentam igual eficácia de adesão em dentina seca ou úmida, devido a sua capacidade de reumidificar e reexpandir as fibrilas colágenas, permitindo a adequada infiltração do adesivo no interior da dentina desmineralizada 21 . Com relação ao desempenho dos adesivos em grupos com o mesmo grau de umidade na dentina, quando o XP Bond foi comparado ao Scotchbond MultiUso em dentina seca (S1 vs S3) não foi encontrada a presença de infiltração marginal.…”

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

“…실제로 건조된 탈회 상아질에 다시 수분을 공급하면 수축된 교원질을 다시 팽창시켜 부피를 원래의 거 의 100％까지 회복시킨다는 보고가 있다 14,15) . 그러므로, 물을 용매로 사용하는 상아질 접착제의 경우, 산부식 후 건조된 상아질이라도 primer에 함유된 수분에 의해 접착과정 중 교원질의 팽창에 필요한 수분을 다시 공 급해 줄 수 있다 [14][15][16] . …”