Proposal for a grading system to determine the clinical status and sequence of permanent teeth eruption: A pilot study

Objectives

The objective of the study was to propose and test a new grading system to quantify the clinical eruption of teeth into the oral cavity. In addition, the study also aimed to apply the grading system to a sample population to determine the chronology and sequence of permanent tooth eruptions, comparing the results with an existing standard table.

Methods

A cross-sectional study was designed, and 1220 children aged 5-18 years were selected from five schools in Chennai. The clinical status of permanent tooth eruption was graded using the newly proposed system. The sequence and chronology of permanent tooth eruptions were determined using Probit analysis and compared with those established by Logan and Kronfeld. The difference in stages of eruption between the sexes was analyzed using the ANOVA test.

Results

The study sample included 515 boys and 705 girls. A total of 23,218 permanent maxillary and mandibular teeth were examined and graded. Of the 11,085 maxillary teeth, 367 were classified as grade 1, 660 as grade 2, and 10,058 as grade 3. Similarly, of the 12,133 mandibular teeth, 497 were grade 1, 793 were grade 2, and 10,843 were grade 3. The eruption of the maxillary canines, second molars, and mandibular second premolars was observed to have occurred earlier than in the traditional table of tooth eruption. The most significant differences in the stages of eruption between the sexes were observed in the 9-12 age group.

Conclusions

The newly proposed grading system was found to be simple, objective, less confusing, and more robust, compared with the existing systems in determining the clinical status of tooth eruptions. The ages of eruption of maxillary canines, second molars, and mandibular second premolars were earlier.

Oral health research: A source for innovative new statistical developments

This article reviews the challenges and opportunities that oral health research may offer to a statistician. To illustrate this, we focus on the Signal Tandmobiel® study, a longitudinal oral health survey that triggered many statistical explorations and developments over the last two decades. For example, non-standard distributions are more the rule than the exception in oral health research. In addition, often measurement error problems need to be addressed. The hierarchical structure of the oral health data also poses non-standard challenges. For instance, caries experience in the mouth is spatially correlated with, however, a specific metric defining the distance between two occurrences. In addition, since caries experience in the context of an epidemiological study is only measured at intervals, analysis of survival involves interval-censoring. Finally, when analyzing a realistic data set in oral health, all the above issues may have to be dealt with simultaneously.