The reasons for the extraction of various tooth types in Scotland: a 15-year follow up.

Objectives: The aim of this survey was to investigate the reasons for extraction of the various tooth types in Scotland. This study replicated one which was undertaken 15 years earlier. A further aim, therefore, was to identify any changes in the frequency of extraction of each tooth type in the 15 years between the two studies.
Methods: The names of every fourth dentist on the list of the Scottish Dental Practice Board were obtained. Four hundred and twenty-five general dental practitioners were asked to record permanent tooth extractions for 1 week. Data requested for each extraction were: the patient's age, gender and dental attendance pattern, the type of tooth removed and the reason for the extraction.
Results: Three hundred and fifty-two dentists participated (a response rate of 82.8%). There were 25% fewer teeth extracted per patient and 30% fewer per dentist than in the 1984 study. In 1999, more teeth of most types were extracted from regular attenders whereas, in 1984, more teeth of all types were extracted from irregular attenders. Premolars and first and second molars were the tooth types most frequently extracted in both surveys. In 1999 premolars were the teeth most commonly removed below 21 years of age, accounting for 57.5% of extractions in this age range. Molars accounted for 33.8% of extractions in this age range compared with 52% in 1984. Overall, caries was found to be the principal reason for loss of all tooth types apart from lower incisors which were extracted mainly for periodontal reasons. However, below 21 years, 84.5% of premolar extractions were performed for orthodontic purposes.
Conclusions: Over the last 15 years, the overall number of extractions has reduced and the proportion of extractions from regular attenders has increased. Proportionately more premolars and fewer molars were extracted from under-21-year-olds. This observation can be explained by an increase in orthodontic extractions or a decline in extractions for caries in this age group. However, when extractions from the population as a whole are considered, caries and its sequelae remains the principal reason for loss of all tooth types other than lower incisors which are extracted mainly for periodontal reasons.