The development and use of forecasting models can stimulate the debate on workforce planning for dentists by improving the quality of the data available, by providing a framework within which the debate can be conducted and by providing a means whereby the effects of different trends and policy options can be measured in a consistent way. The number of dentists on the Dentists Register aged under 60 years may well fall over the 40 years between 1996–2036, while the proportion of female dentists is likely to grow from under 30% to almost 50%. If the present gender differences in dentists’ output persist, the effective ‘whole-time equivalent’ (WTE) size of the dentist workforce could fall by 15%. While future patterns of disease and the efficacy of future treatments are difficult to predict, the demand for dentistry is very likely to increase, given the forecast ageing of the UK population. The number of people aged 65–74 years could increase by 50% to eight million and those over 75 years by 70% towards seven million. Further, almost of all of this greatly increased older population will have retained some of their own teeth. The edentulous adult population was 37% in 1968 and might fall to less than 5% by 2036. These trends taken together could increase the number of courses of treatment per WTE dentist by as much as 40% over these 40 years. Such modelling can help to reduce the degree of uncertainty in future workforce planning.