Microleakage and Shear Punch Bond Strength in Class II Primary Molars Cavities Restored with Low Shrink Silorane Based versus Methacrylate Based Composite using Three Different Techniques

Abstract

Objectives: This in vitro study aimed to evaluate the gingival microleakage in class II cavities in primary molars restored with a low shrink silorane resin composite (Filtek P90) or a nanohybride composite resin(Filtek supreme XT) using three different techniques, (total bonding, closed or open sandwich techniques)lined by nano-filled resin modified glass ionomer cement RMGIC (Ketac N100). Additionally, the shear punch bond strength between the two types of composite and KN100 was also examined. Study design:For microleakage test, two standardized class II slot cavities were prepared in proximal surfaces of 60 sound extracted primary molars which were divided into 2 groups of 30 each according to the type of composite. Each group was subdivided into 3 groups (n = 10) according to the restorative technique used. The restored teeth were examined for microleakage after immersion in 2% methylene blue dye using stereomicroscope at 20 X. Microleakage scores among the groups were compared using Kruskal Wallis test followed by pair wise Mann Whitney U test at P ≤ 0.05. Thirty disc specimens were prepared for determining the shear punch bond strength between the two composite materials and the KN100. Specimens were divided into 5 groups (n = 6) according to the adhesive protocol. The differences in mean bond strength values in MPa between groups were statistically analyzed using ANOVA followed by pair wise Tukey Post hoc test at P ≤ 0.05.Mode of failure was also evaluated for all groups. Results: Both the silorane resin and nano-composite resin showed superior marginal seal with the total bonding technique compared to closed and open sandwich techniques. The recorded mean shear punch bond strength values showed no statistical significant difference between the two resin composites without or with their adhesive bonding systems when bonded to the nano-ionomer. All specimens showed cohesive mode of failures except for silorane resin with Adper Easy Bond Self Etch Adhesive (AEBSEA) which showed adhesive mode of failure. Conclusions: The best marginal seal was obtained with the total bonding technique using both resin composites. The shear punch bond strength between KN100 and the two composite materials was not affected by either of the used adhesive bonding agent.

Microleakage of Nanofilled Resin-modified Glass-ionomer/Silorane- or Methacrylate-based Composite Sandwich Class II Restoration: Effect of Simultaneous Bonding

“…So far, only Fahmy and Farrag 27 have recently evaluated microleakage in Class II primary molar cavities restored with NI/silorane or methacrylate nanofilled composite (open and closed sandwich) and total bonding. They found superior marginal sealing with total bonding compared with two sandwich techniques.…”

Evaluation of Microshear Bond Strength of Light and Chemically-Cured Composite Resins to Light-Cured Glass-Ionomer Using Various Bonding Systems

“…It has been suggested in some studies that cohesive fracture in the substrate can indicate a high bond strength (11); however, some others have reported no relationship between bond strength and fracture type (28,29). In the previous studies, most fractures of GICs and RMGICs have been considered to be of the cohesive type (30,31), which can be attributed to the physical and mechanical drawbacks of the tests used.…”

Evaluation of micro-shear bond strength of resin modified glass-ionomer to composite resins using various bonding systems

“…Some researchers have indicated that cohesive fracture in the substrate is a reflection of a high bond strength;[22] however, some others have reported no relationship between the bond strength and fracture type. [23] In the majority of previous studies most of the fractures of GICs and RMGICs have been of the cohesive type,[24] which might be attributed to the physical and mechanical shortcomings of the tests used in those studies. For example, stresses which are out of the center during the test, small porosities within the cement, which act as foci with the potential of generating stresses and differences in the setting reaction of GI and composite resin[61120] might be factors responsible for cohesive fractures.…”