Applying standard perikymata profiles to Pongo pygmaeus canines to estimate perikymata counts between linear enamel hypoplasias

Objectives

Recently, studies have interpreted regular spacing and average number of perikymata between dental enamel defects in orangutans to reflect seasonal episodes of physiological stress. To estimate the amount of time between developmental defects (enamel hypoplasia), studies have relied on perikymata counts. Unfortunately, perikymata are frequently not continuously visible between defects, significantly reducing data sets. A method is presented here for estimating the number of perikymata between defects using standard perikymata profiles (SPP) that allow the number of perikymata between all pairs of defects across a tooth to be analyzed. The SPP method should allow the entire complement of defects to be analyzed within the context of an individual's crown formation time.

Materials and methods

The average number of perikymata were established per decile and charted to create male and female Pongo pygmaeus SPPs. The position of the beginning of each defect was recorded for lower canines from males (n = 6) and females (n = 17). The number of perikymata between defects estimated by the SPP was compared to the actual count (where perikymata were continuously visible).

Results

The number of perikymata between defects estimated by the SPPs was accurate within three perikymata and highly correlated with the actual counts, significantly increasing the number of analyzable defect pairs.

Conclusion

SPPs allow all defect pairs to be included in studies of defect timing, not just those with continuously visible perikymata. Establishing an individual's entire complement of dental defects makes it possible to calculate the regularity (and potential seasonality) of defects.