Bacterial Colonization and Proliferation in Primary Molars following the Use of the Hall Technique: A Confocal Laser Scanning Microscopy Study

Restorative dentistry aims to create a favorable environment to arrest caries with minimal operative intervention. The Hall technique (HT) involves the seating and cementation of stainless steel crowns (SSC) on primary molars without any tooth preparation, caries removal, or local anesthesia. In this manner, it entombs bacteria and arrests caries’ progress. We compared bacterial distribution and quantity among primary molars affected with caries and restored with SSC using the HT (n = 10), the conventional technique (CT; n = 10), or not restored at all (control; n = 10). The teeth were contaminated with Enterococcus faecalis to mimic the clinical situation in the oral cavity and then incubated for 21 days. They were then cut mesiodistally and evaluated with confocal laser scanning microscopy. Total bacterial load (live + dead) in the mesial and distal areas of the crown showed no significant difference between the groups (p = 0.711), but there were significantly more dead than live bacteria in the CT and control groups versus the HT group (p = 0.0274 and p = 0.0483, respectively). Inside the pulp chamber and the crown area, the total bacterial load was significantly higher in the HT compared to the CT group (p < 0.001). Significantly more dead than live bacteria were observed in all tooth areas treated with the HT (p = 0.0169). Bacterial penetration depth was significantly correlated with bacterial load (p = 0.0167). In conclusion, although more bacteria were present in teeth that had undergone the HT versus those treated with the CT, they were mainly unviable. Additionally, the CT and the HT showed a similar performance in terms of marginal leakage, indicating that complete caries removal is not essential to achieve good sealing.