In this paper, the approach of biodegradation to reduce the environmental impact of plustic wastes is reviewed. The mechanism of biodegradation and the processing and applications of these materials are also discussed in relation to the structural characters of their molecules. The synthetic biodegradable materials such as starch based biodegradable materials are compared with naturdy occumhg biodegmdable materials such as poly(hydr0xy butyrate) (PHB) in terms of their applications, processing difJic u b , and degradation mechanism. The future trends of these materials are anticipated.

Composite resins represent a class of material widely used in restorative dentistry, not only for anterior aesthetics but also as the first choice to restore posterior teeth. However the key limitation in the use of composite resins as a restorative material is related to shrinkage during polymerization which leads to poor marginal seal, marginal staining, restoration displacement, tooth fracture and recurring caries [1].Polymerization shrinkage may affect negatively the clinical outcome of the restoration. Hence the present study evaluates the Polymerization shrinkage of 2 different posterior composites; Filtek Z350(3M) and everX Posterior(GC), using a pycnometer.Independent Sample T-Test was used to determine statistically significant difference in volumetric shrinkage among the tested composite resins. everX Posterior showed comparatively less shrinkage than Filtek Z350; which can be attributed to the presence of silanated e-glass fibres.