Ultrastructure and properties of primary carious molars treated using the Hall Technique

Background: The Hall Technique (HT) is a method of restoring decayed primary teeth using stainless steel crowns (SSCs) without tooth preparation, caries removal, or local anaesthetic. Aim: To investigate the ultrastructural, biomechanical, and chemical characteristics of teeth managed with the Hall Technique in comparison with conventional SSC (controls). Design: Twelve HT-treated primary molars and four controls were analysed. Teeth were dehydrated in ethanol, embedded in methylmethacrylate, mesio-distally sectioned, X-rayed, mounted, and polished. Biomechanical, ultrastructural, and chemical characterisation was performed for carious lesion and sound areas of each specimen. Results: Pre-treatment and post-treatment X-rays showed evidence of little to no caries progression over time. In carious lesions, mean hardness and elastic modulus values were lower in HT-treated teeth than in controls. In both controls and HT-treated teeth, carious lesions had the lowest %wt of Ca and P of all tissues sampled. Conclusions: Although the retained carious tissue was biomechanically more compromised in HT-treated teeth, the Ca and P values were higher than reported elsewhere for carious lesions in primary molars, suggesting remineralisation may have occurred in caries in HT-treated teeth. Future investigations will help elucidate the processes involved with carious lesion arrest under SSC.