Radiographic analysis of primary first molars in pediatric dentistry: a retrospective study

The first primary molar plays a crucial role in maintaining occlusion and guiding the eruption of permanent teeth. This study aimed to analyze the radiographic characteristics of the primary first molar using periapical radiographs and investigate the correlation between root resorption, periapical radiolucency, and various clinical factors.

A retrospective study was conducted using 504 eligible periapical radiographs of primary first molars, obtained from children aged between 3.5 and 10.75 years between April 1 and September 7, 2022. Tooth position, crown condition, root canal condition, root resorption condition, periapical radiolucency, and integrity of the bony crypt of the permanent tooth germ were analyzed. Generalized linear mixed models were performed to determine significant correlations between root resorption, periapical radiolucency, and various clinical indicators.

Pathological root resorption was significantly associated with age (p < 0.0001), with a higher prevalence observed in children aged 6-8 years (30.83%) compared to those under 6 years (9.20%). Pathological resorption was more frequently observed in teeth with deep carious lesions involving the pulp (p = 0.0001) and those containing radiopaque restorative materials (p = 0.0237). Periapical radiolucency was significantly correlated with age, the presence of deep caries, and root canal filling materials (all p < 0.0001), showing a strong correlation between advanced carious lesions and apical periodontitis. Additionally, root resorption was significantly associated with the presence of high-density materials in the root canal (p < 0.0001). The integrity of the alveolar bone plate overlying the permanent tooth germ was significantly affected by the presence of root resorption (p < 0.0001), age (p < 0.0001), and tooth position, with the left and right lower primary first molars showing the higher prevalence of bone plate damage (p = 0.0003).

This study highlights the importance of age and dental caries progression in the pathological resorption of primary first molars. The presence of deep carious lesions and the presence of high-density materials in the root canal are significantly associated with root and periapical changes.