Comparison of the morphology of the primary first molars and the forms of stainless steel crowns used in clinical practice.

This study aimed to assess the difference in the mesiodistal (MD) and buccolingual (BL) dimensions of primary first molars between Taiwanese boys and girls using a three-dimensional (3D) scanner (Microscribe G2 digitizer), record the coordinates in the 3D systems of Graph-R Project and reconstruct 3D images for subsequent analysis. We also determined whether the differences in these parameters between primary first molars and stainless steel crowns (SSC, 3M ESPE, No. 2-7) could be used as a reference for selecting a suitably-sized SSC and performing adjustments during restoration. The results indicated a statistically significant difference in the mesiodistal distance of lower primary first molar crowns between boys (7.75 ± 0.38 mm) and girls (7.41 ± 0.41 mm) ( < 0.05) but no differences in the mesiodistal distance of upper primary first molars between the two sexes. The mean mesiodistal distances of the upper and lower primary first molars of boys were close to SSC size 4 and 3, respectively, while those of girls were close to size 3 in both arches. Overall, the buccolingual distance between the first maxillary and mandibular molars of Taiwanese children was greater than the buccolingual distance between the 3M ESPE SSC. Reducing the buccolingual length of the abutment teeth might quickly help achieve a better fit, reduce chair time, and minimize patient discomfort. In addition, trimming the mesial and distal metal margins of SSCs might help reduce microleakage from the crown margins and improve its retention and survival rate. In conclusion, the 3D scanning and analysis method used in this study can serve as a reference for fabricating SSC to achieve better crown adaptation and improve dental procedures.