Marginal micro-leakage of self-etch and all-in one adhesives to primary teeth, with mechanical or chemo-mechanical caries removal

Statement of Problem: Chemo-mechanical caries removal is an effective alternative to the traditional rotary drilling method. One of the factors that can influence micro-leakage is the method of caries removal

Objectives: To compare the micro-leakage of resin composite in primary dentition using self-etch and all-in one adhesives following conventional and chemo-mechanical caries removal

Materials and Methods: Sixty extracted human primary anterior teeth with class III carious lesions were collected. The selected teeth were divided randomly into two groups each consisting of 30 teeth. In group1 carious lesions were removed using Carisolv multi mix gel. In group 2, caries was removed using round steel burs in a slow-speed hand piece. Then, the specimens in each group were randomly divided into two subgroups [A and B] of 15 and treated by either Clearfil SE Bond [CSEB] or Scotch bond. All prepared cavities were filled with a resin composite [Estellite]. All the specimens were stored in distilled water at 37[degree sign]C for 24 hours and then thermocycled in 5[degree sign] C and 55[degree sign] C water with a dwell time of 20 seconds for 1500 cycles. The specimens were immersed in 1% methylene blue solution for 24 hours, removed, washed and sectioned mesiodistally. The sectioned splits were examined under a stereomicroscope to determine the micro-leakage scores. The data were analyzed using Kruskal-Wallis Test in SPSS version 21

Results: There were no significant differences between micro-leakage scores among the four groups [p = 0.127]. Score 0 of micro-leakage was detected for 60% of the specimens in group 1-A [Carisolv + CSEB], 73% of the group 2-A [hand piece + CSEB], 80% of the group 1-B [Carisolv + Scotch bond], and 93% of the group 2-B in which caries was removed using hand piece and bonded with Scotch bond

Conclusions: Although caries removal using hand piece bur along with using Scotch bond adhesive performed less micro-leakage, it would seems that the use of Carisolv doesn't adversely affect the micro-leakage of composite restorations while using self-etch or all-in one adhesives

Effect of caries removal methods on the shear bond strength of resin and glass ionomeradhesives to primary dentin

Statement of Problem: There is no enough published data about the shear bond strength of resin modified glass ionomer adhesives on caries-affected primary tooth dentin excavated using minimally invasive systems

Objective: To evaluate the shear bond strength of 2 different adhesives [one resin modified glass ionomer and one resin] using two caries removal techniques on healthy and caries-affected primary dentin

Materials and Methods: Two caries removal methods including mechanical [handpiece] and chemomechanical [Carisolv] techniques and two types of adhesives including one resin adhesive [Clearfil SE Bond; CSEB, Kuraray] and one resin-modified glass ionomer adhesive [Riva Bond LC; RBLC, SDI] were used in this study. Ten extracted healthy primary teeth were used for the control group. The teeth were sectioned bucco-lingually and mesio-distally in order to obtain four specimens from each tooth. Thirty suitable specimens were selected as the "control" and randomly divided into two groups of "sound dentin" based on the type of the adhesive used. Sixty extracted caries affected teeth were used for the carious group; sectioned as mentioned above and sixty suitable specimens were selected as the "treatment". Then the specimens were arbitrarily divided into four groups based on caries removal techniques and the type of adhesive used [n = 15]. After bonding with either CSEB or RBLC, the specimens were restored with a resin composite by means of PVC tubes and subjected to the shear bond strength test. The data was analyzed using ANOVA and Tukey's test

Results: The specimens in Carisolv group bonded with CSEB [11.68 +/- 3.1] showed a statistically significant higher mean bond strength followed by those in handpiece group bonded with CSEB [9.4 +/- 2.7], which exhibited higher mean values than those groups with RBLC [p < 0.05]. Shear bond strength values for Clearfil SE Bond was not significantly higher than Riva Bond LC when used in sound dentin

Conclusion: The lowest shear bond strengths for both adhesives were observed on caries-free dentin

Fracture toughness evaluation of hybrid and nano-hybrid resin composites after ageing under acidic environment

Tooth-coloured restorative materials are brittle with the major shortcomings of sensitivity to flaws and defects. Although various mechanical properties of resin composites have been studied, no fracture toughness test data for nano-hybrid composites under acidic condition for a long period of time has been published.To compare the fracture toughness [K[Ic]] of two types of resin composites under tensile loading and to assess the effect of distilled water and lactic acid on the resistance of the restoratives to fracture after three months of immersion.Four resin composites were used: three nano-hybrids [EsteliteSigma Quick [Kuraray], Luna [SDI], Paradigm [3M/ESPE]] and one hybrid, Rok [SDI]. The specimens were prepared using a custom-made polytetrafluorethylene split mould, stored in distilled water [pH 6.8] or 0.01mol/L lactic acid [pH 4] and conditioned at 37°C for 24 hours, 1 or 3 months. They were loaded under tensile stress using a universal testing machine; the maximum load [N] to the specimen failure was recorded and the fracture toughness [K[Ic]] was calculated. Data were analysed by ANOVA and Tukey's test using SPSS, version 18.The results of two-way ANOVA did not show a significant combined effect of material, time, and storage medium on fracture toughness [p= 0.056]. However, there was a strong interaction between materials and time [p=0.001] when the storage medium were ignored. After 24 h of immersion in distilled water, Paradigm revealed the highest [K[Ic]] values followed by Rok, Luna and Estelite. Immersion in either distilled water or lactic acid significantly decreased the fracture toughness of almost all materials as time interval increased. Paradigm showed the highest fracture toughness followed by Rok, Luna and Estelite respectively. As time increased, [K[Ic]] significantly decreased for almost all resin composites except for Luna which showed a slight decrease after one month of immersion in distilled water