Shear bond strength of three natural fiber reinforced conventional glass ionomer cements”: an invitro evaluation

Introduction: Glass Ionomer cement has both the properties of fluoride release which is that of silicate cements and adhesion to dental tissues which is a quality of polycarboxylate cement respectively. It is considered as an excellent restorative material based on its bio-compatibility, anti-cariogenicity, chemical bonding and modulus of elasticity. But GIC lacks colour stability and is not as strong as metallic and composite restorations. Evidence shows that GIC is brittle and easily cracks, due to the low flexural strength. Several modified GIC’s have been introduced to overcome some of these disadvantages. The most common being resin modified and filler incorporated GIC’s. In this study naturally available fillers like silk, flax seed and cellulose are incorporated into conventional GIC. These fibers are biocompatible, economical and with better handling and easy mixing properties. These experimental samples of fiber reinforced GIC’s were subjected to shear bond strength and the results compared and concluded.
Methodology: 80 extracted premolar teeth were collected from available sources. After removal of debris, calculus and soft tissue from the tooth surface, the teeth were stored in 10% formalin solution until further use. The teeth were randomly distributed into 20 samples each of 4 groups. Silk particles extracted from Bombyx mori silkworm cocoons were incorporated into conventional type 2 GIC (GC, CORP, JAPAN) at 3% by weight. Cellulose and flax fibers were also collected from sources and incorporated into conventional type 2 GIC at 5% weight and 25% weight respectively. The tooth specimen were then sectioned to expose dentine and polyacrylic acid conditioning was done .Plastic straws of 3mm diameter were cut into mould of 3 mm in height and placed on the conditioned dentine surface. The reinforced GIC materials were manipulated and placed into thede moulds with a condenser. After setting the samples were subjected to shear bond strength using a universal testing machine at a cross head speed of 0.5 mm per minute and values recorded.
Results: Group 4(flax fiber modified GIC) showed the highest shear bond strength (3.4242 Mpa) followed by Group 1(unmodified GIC) with 3.3903 Mpa.Group3 (cellulose modified GIC) showed the least bond strength value (2.2679 Mpa).The intergroup comparison revealed that there was significant difference between the groups (p<0.05))
Conclusion: Flax fiber reinforced GIC showed better shear bond strength to dentin than conventional GIC. Further research is needed to advocate the use of natural fibers as fillers in GIC.