Variables related to materials and preparing for bond strength testing irrespective of the test protocol

Abstract

Resin bonding can be compared to making a sandwich with the tooth on one side and the restoration on the other, a layer of bonding resin is applied to either side and a filled resin (composite) placed in between.

The materials to be bonded may be either ceramic, metal or composite. These may be formed by various methods such as casting, pressing, sintering or machining.

In the case of metals and ceramics there is no requirement to age the surfaces prior to bonding whereas with composites, a number of studies have attempted to age the composite substrate in order to mimic the situation of bonding new composite to old composite in the mouth.

It is normal to prepare the bonding surfaces of the teeth and restoration prior to the application of the bonding resin. This normally involves a combined physical and chemical approach (e.g. sandblasting + silanation).

Having prepared the surfaces the testpiece is assembled. The assembly protocol may attempt to mimic the clinical situation, which is relatively uncontrolled, or attempt to control variables such as the precise location of the restoration and the “seating force”.

Having completed the assembly the testpiece may be aged prior to testing. In vitro aging is a function of time and environment plus additional features such as thermal or mechanical cycling.

This paper considers these factors; but is limited to preparation of the restoration side of the sandwich.