Model-Based Cost-Effectiveness of Direct Restorations: Amalgam Dominates.

Area of Science:

• Dental materials science
• Health economics
• Public health policy

Background:

• Dental amalgam use is mandated for phase-down, with a 2030 phase-out feasibility study in England.
• Amalgam remains predominant for posterior restorations in English NHS care, but access is limited.
• Understanding the long-term economic and clinical implications of amalgam vs. composite restorations is crucial.

Purpose of the Study:

• To quantify the relative long-term costs and consequences of amalgam versus composite direct posterior restorations.
• To compare outcomes for adult permanent teeth within the English National Health Service (NHS) setting.
• To inform policy decisions regarding the feasibility of amalgam phase-out.

Main Methods:

• A microsimulation model was developed using TreeAge Pro, based on literature review.
• The model simulated restoration failure and reintervention for 10,000 18-year-old NHS patients over a lifetime horizon.
• Costs and outcomes were discounted at 3.5%, employing an extended medical-sector and societal perspective with sensitivity analyses.

Main Results:

• Amalgam restorations were less costly (£70 patient, £34 funder) and more durable (4 years, 12 non-discounted) than conventional and bulk-fill composites over a lifetime.
• Amalgam resulted in fewer visits (1), less treatment time (43 min), and lower laboratory costs (£8).
• Time until direct restoration was no longer possible was significantly longer for amalgam (6 years, 17 non-discounted).

Conclusions:

• The model demonstrated good validity, predicting tooth survival aligned with NHS claims data.
• An amalgam phase-out in England, without substantial clinician upskilling and health service changes, will likely increase lifelong costs and negatively impact restoration and tooth survival.
• Such a phase-out risks reduced societal productivity and exacerbation of existing access to care and socio-economic inequalities.