The Effect of Different Lining Strategies on Amalgam Restorations

The aim of this research is to compare the clinical outcome of amalgam restorations placed in conjunction with three different lining protocols, each of which represents a different therapeutic concept.

Patients attending one of eight, United Kingdom general dental practitioners for a new restoration in a posterior tooth will be recruited and informed consent obtained. Each dentist will place 20 amalgam restorations either unlined (control), or lined with calcium hydroxide cement, rmgi cement, or sealed with a resin bonding agent (total - 640). Pre-operative radiographs and pulp testing will be performed and measurement of cavity size to assess the remaining dental thickness. The pulp status and symptoms will be recorded at 6, 12, and 24 months. Post-operative sensitivity will be recorded by the patient at 1, 3, 7, 14 and 28 days using a visual analogue scale and diary. The dentists will be trained and calibrated to use United States Public Health Service criteria and the condition of the restoration will be assessed at 12 and 24 months. For each lining option, one product and one admixed amalgam will be provided for use by all the dentists. Training and instruction will be given on the application of the liners and on amalgam condensation to increase standardisation. The collected data will be assessed to identify any association between the outcome variables and the pre-treatment tooth condition or lining material used using logistic regression (α=0.05).

Inclusion Criteria: Healthy adults over 18 years Presence of one or more carious cavities extending beyond the outer 1/3 of the dentine Able to give valid consent to participate in study Willing to receive an amalgam restoration in a target tooth Teeth free from pain Teeth with vital pulps Exclusion Criteria: Replacement restorations Psychiatric conditions or medication which may affect pain perception. Cavities limited to the outer ⅓ of dentine. Teeth with existing symptoms or sensitivity Patients under 18 years Non-vital teeth Allergy or idiosyncratic reaction to the study materials Inability to return for review Fractured or cracked teeth Pregnancy or breast-feeding