Sir, as a teacher of undergraduate endodontics and a practitioner of endodontics for nearly 30 years, I find that the basis of Dr Mackay's statements could be equally accused of being illogical and in disregard of a scientific evidence-based approach (BDJ 2008; 205: 295–296).

We currently teach chemo-mechanical preparation techniques, where emphasis is based upon the chemical disinfection of the root canal utilising sodium hypochlorite irrigation. Mechanical preparation enlarges and shapes the canal to aid penetration of the irrigant into the depths of the dendritic root canal system, and creates the flared (variable taper) funnel-shaped preparation which maximises the obturation of the 3D intracanal space; primary concepts supported by a wealth of published literature.

If these concepts are valid then rubber dam provides three basic functions: prevention of irrigant leakage from the root canal into the oral cavity; prevention of gross contamination of the root canal by saliva during preparation and before the coronal seal; and the vital medico-legal importance in protection of the patient from inhalation or ingestion of loose instrumentation. I believe that it then becomes a mandatory requirement to use rubber dam where we use the above techniques. There is a wealth of independently published data detailing endodontic success rates that are higher when these protocols are used and lower when they are not. This is not a 'specialist endodontist' conspiracy to charge higher fees but a genuine effort to control all variables and to maximise success for our patients.

Single-visit procedures produce potentially the highest success rates due the initially lower levels of bacterial contamination of the dentinal and pulpal spaces, and the ability to provide a substantial coronal seal all in one visit. Success rates in endodontics are yet another contentious area, and I am not able to state that my success rate is 'a near perfect success' unlike Dr Mackay. It all depends upon your criteria for success, which may only be a lack of reported clinical signs or symptoms, but I would be very interested in the longer term radiographic evidence of periapical tissue healing and maintenance of tissue health in his patients.

Endodontic research is developing new 'super oxidising' irrigants with greater efficacy but less tissue toxic effects. Photo-activated disinfection with laser activated disinfection solutions for the treatment of root canals, and also periodontal pockets, is well advanced and linked into this concept of disruption or inactivation of the biofilm.

I recognise many of Dr Mackay's statements from when I was newly qualified in 1981 but they do not reflect the concepts of 2008. I would urge all practitioners to carefully examine their own techniques, and standards as legally these will be judged against current teaching.