Sir, I am well aware that there is a British bias about the philosophy of science, and that it is considered academic, boring and irritating. Nonetheless an epistemological approach to ozone, as now being debated in the BDJ, seems necessary and appropriate.

In the history of science any new theory contrasts with sets of assumptions, rules and practices of the paradigm it challenges, and the transition from one paradigm to another does not necessarily involve verification or falsification of scientific theories.1

The fact that the Cochrane Institute2 issued a report on the studies on the remineralisation effects of ozone does not imply that the studies and the naturalistic observations accumulated over a number of years are non-existent. In addition, the respect that Cochrane enjoys does not necessarily imply that the conclusions of the report are congruent with the results. In fact, even if the way in which naturalistic observations are described and translated into experimental and linguistic schemes may appear inadequate for some. The same naturalistic observations witness that something is happening, something which adds in this case, a new perspective to our theories on dental decay and remineralisation.

Therefore there is no incongruence in reviewing a book relating to a new theory and vision, even if it generates some controversies.3 For those who have been involved in the genesis of a new vision, any criticism generated by intellectual honesty is more than welcomed as it enriches the points observed. Epistemiology is the critical analysis of science and answers the question: how do we know what we know? Dental decay is a controversial topic. It is well established that the natural history of dental decay depends on two sets of factors, local and systemic. For some reason most dentists seem to ignore the systemic aspects of decay. An example is the use of salivary tests. At the recent FDI Congress in Montreal we witnessed the promotion of the measurement of saliva buffering capacity to assess caries risk. We have known for many years that it is an evidence-based practice but still, for some reason, it is not in widespread use.4

By the same token, caries cannot any longer be reasonably described as holes, since the lesions are the consequences of demineralisation and enzyme activity. Why we do not focus our attention on the very early stages as routine?

Ozone acts topically with its effect related to the local medium and it is clear and evident that it also indirectly induces remineralisation. It acts directly on the local dentinal environment where it restores homeostasis, facilitates the expression of tissue specialisation and makes any systemic condition ephemeral. However, we still know very little about the biomolecular environment in which local and systemic conditions interact.

Ozone offers the opportunity to help investigate this grey area. Caries is now considered to be a metabolic process which can be reversed and whose diagnosis and metabolic reversion are determined by metabolic activities. In our studies in Italy, ozone treatment has reversed 92% of early carious lesions which has never been possible previously by any other method. This is the new vision. This is the revolution and the challenge. I fully support the book review by Dr Hayes.