Chemical stability of resin composite and amalgam restorations in head and neck cancer patients after radiotherapy

ABSTRACT

Dentists should realize that restorative materials intended to be used in patients receiving radiotherapy in the head and neck regions, must be capable of withstanding standard radiation dose [6070Gy = 6000-7000 rad] without serious changes in their functional stability. Two types of each of the currently used restorative amalgam and resinous composite, namely amalgam world and amalgam cap, as well as composite arabesk and composite pekalite, were employed throughout the present work. A factorial experiment was designed to evaluate their radiation sensitivity. Using 6 Mev photon beam, standardizely prepared samples were exposed to two doses of 60 and 70 Gy representing the usual dose range that are delivered as postoperative or radical radiation dose respectively. In comparison with the controls, radiation sensitivity of the different restorations was estimated via changes in properties known to be closely relevant to their successful functionality. The properties followed were electrochemical corrosion, chemical solubility, hardness microstructure and surface roughness. Though the statistically treated results obtained offered only a partial set of judgment criteria, it was concluded that amalgam cap and composite arabesk appeared to possess the most functional durability with respect to the corresponding class of each. Moreover irradiated amalgam cap acquired more noble character in resisting corrosion attack, while irradiated composite arabesk gained a significant increase in its mechanical hardness and disintegration resistance as a result of undergoing cross-linking reaction