Caries experience in primary molars and its impact on the variability in permanent tooth emergence sequences.

Objectives: A history of caries in the primary molars is associated with an advanced emergence of their permanent successors. Hence, caries in the primary molars may have an impact on the emergence order of the permanent teeth. The aim of the present study was to fully investigate the variability in permanent tooth emergence, taking into account the (caries) status of the primary molars.

Methods: For this purpose data available from the Signal Tandmobiel project were used. In this prospective longitudinal survey data were collected from a representative sample of 4468 children, examined yearly by trained dentist-examiners. Bayesian statistical analyses taking into account the interval-censored character of the data were performed.

Results: 56% of all examined primary molars were sound; between 2.5 and 7.2% of the first and second primary molars were extracted due to caries. When both primary molars were sound, the most prevalent emergence order was '4-3-5-7' (first premolar-canine-second premolar-second molar) in the maxilla and '3-4-5-7' in the mandible. When both maxillary primary molars were affected by caries (i.e., decayed, filled or extracted due to caries), the sequence '4-5-3-7' was the most prevalent whereas sequences '3-4-5-7' and '4-3-5-7' were less prevalent. When both mandibular primary molars were affected by caries, the prevalence of sequences '4-3-5-7', '4-3-7-5' and '4-5-3-7' increased whereas the prevalence of sequences '3-4-5-7' and '3-4-7-5' decreased.

Conclusions: A history of caries in the primary molars is associated with an altered emergence order of canines, premolars and second molars.