Introduction

Sir, some of the materials we use in the mouth can be harmful when used inappropriately. Your recent article on bony necrosis following the use of paraformaldehyde paste (BDJ2007;  203: 511–512) beautifully illustrates this point.

In the first two cases, the precise method of usage is not mentioned but the radiograph and report on the third case show that material was placed contrary to the manufacturer's instructions, ie not sealed within the tooth by a cement such as a poly-carboxylate. In common with many of our materials, the safe use of paraformaldehyde is technique sensitive and Case 3 demonstrates the consequences of an inappropriate technique. The fault was therefore with the operator and not the material.

Perhaps it would be wise for us to consider appraising our techniques before we condemn our materials. One would not wish to be the bad workman who blames his tools.

Your publication has reported various cases where hypochlorite has caused terrible tissue damage and pain when it has been used with an inappropriate technique and yet there is no similar call for the use of hypochlorite 'to be strongly discouraged in all instances'.