This study was conducted for the purpose of evaluating the stainless steel crowns on extracted primary molarsand thus identifying frequent errors and defects. Visual assessment and micro-computed tomography (micro-CT) image analysis were performed on 97 primary molars for evaluation of the state of marginal adaptation,cement loss, secondary caries, ledge formation, attritive perforation and marginal polishing defect. The resultswere as follows:In the examination of object teeth by evaluation criteria, cement loss was found most frequently (98%),followed by secondary caries (42.3%), marginal polishing defect (41.2%), ledge formation (29.9%) and attritiveperforation (17.5%), in this order. The cement loss at the margins showed a significant relationship withmarginal gap and secondary caries: the larger the marginal gap is, the more frequent is the cement loss (p <0.05). The average marginal gap was 0.31 ± 0.26 mm and showed the highest value in the maxillary 2nd primarymolars. The location of the crown margin above the cementoenamel junction was found most frequentlyand it was found that the higher the crown margin is located, the less the marginal gap becomes (p < 0.05).
In conclusion, it is thought very desirable to pay closer attention to crown margins and shapes for stainlesssteel crown restoration in order to minimize the marginal gaps and consequent cement loss.