Hydrolytic Degradation of a PPF Modified Hybrid Composite Resin

Aim: The aim was to examine the effect of a prepolymerized filler (PPF) additive on the resistance to hydrolytic degradation of a hybrid composite resin.

Materials and Methods: Two commercial materials (Kerr- Sybron) were studied: (A) Point 4 and (B) Premise. A is a hybrid resin containing fillers of submicron barium glass and nano silica. B is a modified version of A in which a third filler, a silica- containing PPF, is incorporated to reduce curing shrinkage. Light cured discs (n=3), 10mm × 3mm, of each material were subjected to degradation in 0.1N NaOH at 60^oC for 3 wks [Sarkar, J Biomed Mater Res (Appl Biomat 53, 37, 2000]. Resistance to degradation was evaluated in terms of (a) mass loss, (b) Si loss, and (c) subsurface degradation depth.

Results: The data (mean ± st. dev.) for different degradation parameters are shown below.

Material	Mass Loss         (%)	Si Loss             (ppm/cm2)	Degradation Depth           (µm)
A	2.58 ± 0.32	65.28 ±  2.47	184.64 ± 20.37
B	3.73 ± 0.28	123.30 ± 2.41	428.93 ± 34.59

The difference between the two brands, Point 4 and Premise, with respect to each parameter was highly significant (p< .001).

Conclusion: The addition of PPF particles to a hybrid composite resin reduces its resistance to hydrolytic degradation. The deleterious effect of PPF on degradation resistance of composite resins as observed in this study is similar to that previously reported for traditional heterogeneous microfils [2003 IADR, #3028 and 2004 IADR, #3133].