Evaluation of the pit and fissure system in primary and permanent molars with micro-computed tomography and 3D printing.

This study aimed to characterize the anatomical and physiological features of pits and fissures in primary and permanent molars by microtomographic (micro-CT) examination and three-dimensional (3D) printing. The occlusal surfaces of 84 primary molars and 60 permanent third molars were examined. The samples were scanned with micro-CT and the occlusal surface separated. The areas of the crown, its occlusal part, and fissures and pits were calculated. Digital impression of the occlusal surface was created and 3D printed. The frequency of different fissure types was determined by direct observation. Data were subjected to statistical analysis using Mann-Whitney U Test and chi-square test (p < 0.05). There was statistically significant difference between the ratio of occlusal surface and the crown area for the molars in primary and permanent dentitions (24.78% and 28.85% respectively, p < 0.05). In terms of the percentage ratio of the fissure area to the occlusal surface (24.24% and 22.30%) and the fissure area to the crown (6.02% and 6.52%), no significant difference was observed (p > 0.05). V-shaped fissures were predominant in both primary and permanent teeth, with a higher occurrence in primary dentition (59.48%, p < 0.05). Permanent molars exhibited a higher prevalence of I-type and U-type fissure configurations compared to primary molars (p < 0.05), with I-type fissures being the least common in primary molars. In both dentitions there was no statistically significant difference in the prevalence of IK-configuration (p > 0.05). The fissure depth was significantly greater in permanent molars than primary molars (p < 0.05). In conclusion, this study revealed remarkable diversity in fissure morphology among primary and permanent molars.