Numerical finite element analysis of periodontal ligament after restoration of primary molars with stainless steel crowns

Background: Uncertainty in occlusal height adjustment after restoration of primary molars with stainless steel crowns (SSCs) under general anaesthesia. Methods: The objective of this study is to assess the impact of augmented occlusal height on the periodontal ligament (PDL) following the restoration of primary molars with SSCs, utilizing three-dimensional finite element analysis (3D-FEA). Cone-beam computed tomography (CBCT) images of one male and one female child aged 3, 6 and 8 years were selected. The three-dimensional (3D) models were constructed and subsequently grouped as follows: Group A, deciduous molars not restored by SSCs (control group). Group B1, deciduous molars restored to normal occlusion using SSCs. Group B2, first deciduous molars restored to normal occlusion using SSCs. Group B3, second deciduous molars restored to normal occlusion using SSCs. Group C1 utilized SSCs to restore the first and second deciduous molars to an occlusal increase of 1 mm. Group C2 applied SSCs to restore the first deciduous molars to an occlusal increase of 1 mm. Group C3 utilized SSCs to restore the second deciduous molars to an occlusal increase of 1 mm. Group D1 employed SSCs to restore the deciduous molars to an occlusal increase of 2 mm. Group D2, the first deciduous molars, were restored with SSCs to an occlusal increase of 2 mm. Group D3, the second molar was also restored with SSCs to achieve an occlusal increase of 2 mm. Loads were applied at angles of 0, 45 and 90 degrees separately to ten sets of models for each child using 3D-FEA to evaluate the biomechanical effects on the PDL. Results: A statistically significant difference in maximum Von-Mises stresses within the PDL was observed between groups B1 and A (p < 0.01). A positive correlation was observed between occlusal height following SSC restoration and maximum von-Mises stress in the PDL (p <0.01). The maximum vonMises stress in the PDL exhibited a positive correlation with the occlusal height of the SSC restorations, and a negative correlation with the loading angle and age (p < 0.01). Conclusions: It is advised that the occlusal height of molar teeth restored with SSC be maintained at a level within a range of 2 mm.