[Shear bond strength of two self-etch adhesives to permanent and deciduous dental enamels: effect of acid preconditioning]

There are some studies that strongly recommend acid-conditioning before applying the self-etch adhesives. The aim of this in vitro study was to compare the shear bond strength [SBS] of two self-etch adhesives to the enamel of primary and permanent teeth with acid preconditioning. The buccal surfaces of 48 permanent molars and 48 primary molar teeth were prepared for bonding of the adhesives to the enamel. Then the samples were randomly divided into eight groups, each containing 12. According to the manufacturers' instructions, Clearfil SE Bond [CSEB] and ACE All Bond SE [ABSE] self-etch adhesives were applied on the enamel and the etched enamel of both permanent and primary teeth and bonded with composite resin. After 24 hours of storage in 37°C and 500 rounds of thermocycling, the specimens were tested in a shear at a crosshead speed of 1.0 mm/min. The results were statistically analysed using SPSS 11.5 with Kruskal-Wallis and t-test at a significance level of 0.05. The mean +/- SD in permanent enamels using CSEB and ABSE were 16.10 +/- 7.6 and 8.49 +/- 2.34 Mpa, respectively. The same data for the deciduous enamels were 16.08 +/- 3.91 and 9.23 +/- 3.20 Mpa, respectively. After acid etching, SBS for permanent enamel using CSEB and ABSE were 32.05 +/- 7.13 and 31.39 +/- 6.51 Mpa, respectively. The same data for deciduous enamels were 24.73 +/- 10.74 and 21.70 +/- 6.18 Mpa, respectively. The bond strength of CSEB was significantly higher than ABSE adhesive in both primary and permanent teeth. In addition, acid etching leads to increase in the enamel bond strength of both studied adhesives

[Shear bond strength of two self-etch adhesives to permanent and deciduous dentin: Effect of acid preconditioning]

Statement of Problems: Enamel preconditioning using phosphoric acid has been recommended prior to applying self-etch adhesives. Meanwhile, there is the possibility for etching of the dentin

Purpose: The aim of this study was to evaluate the shear bond strength [SBS] of two self-etch adhesives to the dentin of the primary and permanent teeth in case of phosphoric acid preconditioning

Methods and Materials: In this experimental study, the buccal surfaces of 48 permanent molars and 48 primary molar teeth were prepared for bonding of two self-etch adhesives including Clearfil SE Bond [CSEB] and ACE All Bond SE [ABSE], to the dentin. Each of the permanent and primary teeth was randomly divided into 4 groups [n=12]. According to the manufacturers' instructions, CSEB and ABSE were applied on the dentin or etched dentin of both permanent and primary teeth, then, they were bonded with composite resin. The specimens were stored in water at 37[degree sign]c for 24 hours and then were thermocycled for 500 cycles. SBS was performed at a crosshead speed of 1.0 mm/min using DARTEC universal machine. The results were statistically analyzed in SPSS 11.5 using Kruskal- Wallis and T-Test

Results: The bond strength of CSEB was significantly higher than ABSE adhesive in both primary and permanent teeth [p =0.001]. Acid preconditioning significantly increased the dentin bond strengths of ABSE adhesive in the primary and permanent dentin [p =0.001], and CSEB adhesive in primary dentin

Conclusion: Bond strength of the studied adhesives was significantly different. While acid phosphoric preconditioning improved the bond strength of the both adhesives in primary teeth, it did not influence the bond strength of the studied two-step self-etch adhesive in the permanent dentin

Isolation of mesenchymal stem cells from dental pulp of exfoliated human deciduous teeth

The exfoliated human deciduous tooth [SHED] contain multipotent stem cells that identified to be a population of highly proliferative and clonogenic .These cells are capable of differentiating into a variety of cell types including neural cells, adipocytes, and odontoblasts. Normal exfoliated human deciduous incisors collected from six- to nine-years-old children. The pulp was separated from the crown and digested with collagenase .Single cell solutions were cultivated in alpha-MEM supplemented with ES-FCS. After two to three days, the cells reached confluency and were trypsinized and cultured for further passages. The passage-4 cells were analyzed with CD34, CD45, CD105, CD166, CD31, CD90 and CD146 markers that indicated these cells had a mesenchymal stem cell [MSC] identity. We examined the cells for Alkaline Phosphatase activity to investigate the mesenchymal [stromal] nature.Finally, the cells were differentiated into the osteoblastic and adipocytic lineages in different subcultures and analysed by RT-PCR and different staining protocols. Viable cells growing out of the explants showed elongated shapes in clusters. These cells showed alkaline phosphatase activity. Flow cytometry results revealed high expression of pluripotent stem cell markers .In some area of the osteoinductive cultures nodule-like structures were observed that showed red mineralizing area upon staining with Alizarin Red.In adipogenic cultures lipid vesicles appeared after five weeks of induction with Oil Red. This study show that pulp contains cells with high plasticity and proliferation capacity and can be easily isolated without any serious intervention