Abstract:

Objective This study aims to analyze the related factors of ectopic eruption of adjacent first permanent molars after the restoration of stainless-steel crowns of the second primary molars. Methods The experimental group consisted of 19 patients, and 25 second primary molars with stainless steel crown restorations were examined. The patients presented with ectopic eruption of the corresponding first permanent molars. The control group included 19 patients, from whom 29 second primary molars with stainless steel crown restorations were examined. Notably, the corresponding first permanent molars erupted normally. The panoramic radiographs of all participants were analyzed, and va-riables, such as patient age, gender, ectopic eruption positions of the first permanent molars, and the distal margi-nal adaptation of the stainless-steel crowns, were asses-sed. The tilt angles of the first permanent molars, second primary molars, and the intersection angle between the long axes of the two teeth were measured. Data were subjected to statistical analysis using Pearson’s chi-square test and independent t-tests. Results A significant positive correlation was identified between the distal marginal adaptation of the stainless-steel crowns and the ectopic eruption of the corresponding first permanent molar (OR=9.14, 95% CI: 1.06-79.26, P<0.05). Compared with the control group, the experimental group exhibited a smaller angle between the long axes of the maxillary first permanent molar and the second primary molar (6.51°±4.46°, P<0.05). Additionally, the mandibular first permanent molar had a more pronounced inclination (43.66°±10.56°, P<0.05), and the angle between the long axes of the mandibular first permanent molar and the second primary molar was significantly larger (25.39°±10.79°, P<0.05) in the experimental group. Conclusion Prior to the restoration of second primary molars with stainless steel crowns, evaluating the potential risk of ectopic eruption of the corresponding first permanent molar is essential. This step is particularly important when ectopic eruption is present in the remaining quadrants. When the angle between the long axes of the maxillary first permanent molar and the second primary molar is excessively small, the inclination of the mandibular first permanent molar is extremely large, or the angle between the long axes of the mandibular first permanent molar and the second primary molar is extremely large, the use of stainless-steel crowns should be minimized, or preventive measures should be considered. Special attention must be given to the distal marginal adaptation during stainless steel crown restoration to prevent the formation of steps on the distal surfaces.

Key words: stainless steel crown, ectopic eruption of the first permanent molar, panoramic radiograph