Calcium leaching from dentin and shear bond strength after etching with phosphoric acid of different concentrations

Abstract

Based on the H2O-P2O5-CaO phase diagram, we hypothesize that a phosphoric acid concentration around 27 wt% leaches most calcium from dentin. We also hypothesize that bond strength is affected by resin infiltration, and that resin infiltration becomes incomplete when calcium leakage exceeds a certain value. Dentin disks were cut from human molars. Eight phosphoric acid concentrations were prepared (15.7-51.2 wt%). For each acid group, there were four etch time subgroups (15, 30, 60 and 120 s). The dentin disks were etched in acid and rinsed in water for times corresponding to 15 s, 30 s, 60 s and 120 s. The calcium concentrations were analyzed using atomic absorption spectroscopy. Composite cylinders were bonded to the remaining parts of the teeth using the same etching protocol, and shear bond strength was determined. The 29.2 wt% group demonstrated the highest and the 15.7 wt% group the lowest calcium leaching value. Even though there were trends towards lower bond strength for longer etch times, a statistically significant difference was only found between 30 and 120 s. There was no significant correlation between calcium leaching and bond strength. The results support the tested hypothesis that the highest leaching value would be around 27 wt% phosphoric acid.

Shear bond strength of self-etch and total-etch bonding systems at different dentin depths

“…2 During dentin acid-etching, the mineral content of the dentin surface is removed, and the collagen fibrils remain supported by water. 3 The moist bonding technique prevents the collagen fibers from collapsing and provides stability to the collagen, thus enabling greater infiltration of adhesive monomers. 4 However, some studies have found that the resin monomer infiltration may be incomplete even when the "wet" bonding technique is used, 5 suggesting that another factor affect hybridization, the composition of adhesive systems.…”

Comparison of shear bond strength of different universal adhesive systems using the modes etch and rinse and self etch

“…Bu duruma asit uygulanan gruplarda kullanılan %35'lik fosforik asitin hidroksiapatit kristallerini ve dolayısı ile kalsiyumu ortamdan uzaklaştırarak, kimyasal bağlantıyı ortadan kaldırması veya azaltması neden olmuş olabilir. Yapılan çalışmalarda yüksek bağlanma değeri göste-ren örneklerin koheziv ve karışık tip başarısızlık gösterir-ken, düşük bağlanma değerlerine sahip örneklerin daha çok adeziv başarısızlık gösterdiği rapor edilmiştir (40)(41)(42). Bu çalışmada da örneklerin çoğunda karışık veya koheziv tip başarısızlık gözlenmiştir (Resim 2).…”

"Avaliação da resistência adesiva e do padrão de condicionamento da dentina e do esmalte após a aplicação do ácido bórico a 2%".

“…Na superfície que recebeu o tratamento com o ácido fosfórico a 35%, por 15 segundos, pode-se observar a presença de túbulos dentinários totalmente desobliterados, remoção completa da "smear layer" com ausência de "smear plugs" e dentina peritubular e intratubular bem definidas. Essas características morfológicas também foram observadas nos trabalhos de JACOBSEN et al 51 , em 2000, TEBECHRANI;…”