Preformed metal crowns (PMCs) have high success rates in restoring primary molars in children but they were not generally used by dentists, especially in developing countries due to its demand of high clinical skills with the conventional technique (CT). The biological approach, Hall technique (HT), requires less training and can be placed by less experienced dental operators including therapists. Previous studies were mainly carried out in developed countries. The aims were to investigate and compare the efficacies and cost-effectiveness of PMCs placed by these two techniques.

A prospective randomised control trial design was used. The study was carried out in a dental practice in Sudan, an under-developed country with lower social economic group. Children between 5-8 years were invited and selected if they met the inclusion criteria. Only those who had 1-2 carious primary molars needing PMCs were randomised. The PMCs were placed by a dentist in the CT arm and by a therapist in the HT arm. The children were follow up every 6 months up to 2 years. The demographic details, periodontal health, occlusion, children anxieties, and procedure time were recorded. The Kaplan-Meier survival rates for each arm were calculated. The incremental cost effectiveness ratio (ICER) was calculated using the results and the local salaries

Inclusion Criteria:

• Healthy children with Class I or class II carious primary molars

Exclusion Criteria:

• Had a compromised medical history
• Were pre- or un-cooperative to have clinical examinations
• Lived in remote villages and were unlikely to return for follow-up
• Had teeth with pain or sepsis
• Had teeth with caries extended in pulp either from clinical or radiographic examinations