A 24-month retrospective study of preformed metal crowns: the Hall technique versus the conventional preparation method

Purpose: Conventional and Hall Technique (HT) Preformed Metal Crowns (PMCs) are used for treatment of carious primary molars. The aim was to evaluate the clinical and radiographic success of conventional and HT PMCs in a postgraduate dental setting. Methods: A retrospective study using patients’ electronic case-notes and radiographic images of carious primary molars treated with either conventional or HT PMCs was conducted to assess clinical and radiographic success/failure. A Kaplan–Meier curve was used to assess PMC survival. Results: 187 PMCs (110 HT and 77 conventional) in 65 children (34 females and 31 males) at 6, 12, 18 and 24 months were assessed. At 24 months, the success rates of conventional and HT PMCs were 97.6% and 93.5%, respectively. Two HT (perforated/abscessed) and four conventional (abscessed) PMCs failures occurred. There was no significant difference in success/failure (p = 0.362) at 12 months, but the HT was more successful at 24 months (p = 0.002) with similar survival times for both methods. Conclusion: HT and conventionally placed PMCs, when placed in a postgraduate paediatric dentistry setting, were clinically and radiographically very successful at 6, 12, 18 and 24 months post operatively with a slightly higher success of the HT at 24 months.