Analysis of the dimensions of temporary molar crowns on digital study models: cross-sectional study

Introduction: The analysis of primary molar crown dimensions using digital study models is an important aspect of pediatric dentistry and orthodontics, allowing accurate morphometric assessment of primary teeth. Objectives: To characterize the crown dimensions of primary molars by measuring the mesiodistal, vestibulolingual/palatal dimensions and crown height of deciduous molars from a group of Portuguese children aged between 7 and 13 years, using intraoral scanner images (iTero). To analyze whether there are significant differences in the measurements based on variables such as sexual dimorphism, differences according to dental side of the dental arch, the variation in molar dimensions in different age groups, and the presence of correlation between the variables. Methodology: A cross-sectional study was conducted using STL files obtained from intraoral scans of 100 Portuguese children aged 7–13 years. The inclusion criterion was children aged between 7 and 13 years. Exclusion criteria comprised restored primary teeth, carious primary teeth, partially erupted primary teeth, and primary teeth presenting developmental defects. The mesiodistal, buccolingual/palatinal dimensions and crown height of the first and second primary molars were digitally measured on three-dimensional models. Statistical analysis was performed using SPSS software. All measurements were performed by a single examiner and independently verified by a second examiner. Results: The crown dimensions of the first and second primary molars showed low variability across the sample. The overall mean mesiodistal dimension was 7.68 ± 0.04 mm, with slightly higher values in males (7.76 ± 0.06 mm) than in females (7.59 ± 0.06 mm). Similarly, the overall mean buccolingual/palatinal dimension was slightly higher in males (8.57 ± 0.07 mm) than in females (8.29 ± 0.08 mm). The mean mesial lingual/palatal cusp height was 3.88 ± 0.05 mm in males and 3.80 ± 0.05 mm in females, while the mean distal lingual/palatal cusp height was 3.23 ± 0.06 mm and 3.22 ± 0.06 mm, respectively. However, no statistically significant differences were found between sexes, age groups, or homologous teeth (p > 0.05). Strong positive correlations were observed among the three crown dimensions evaluated. Conclusion: This study provides reference morphometric data for the crown dimensions of first and second primary molars in Portuguese children aged 7–13 years. The evaluated dimensions showed a homogeneous distribution and low variability, suggesting relatively stable morphometric characteristics within this population.