Longitudinal Results of a 10-Year Clinical Trial of Repair of Amalgam Restorations

Study Design A cohort of 20 patients between the ages of 18 to 80 years old (mean 26.5 years), female (58%) and male (42%), with 40 (Class I and Class II) amalgam restorations, that presented one or more clinical features that deviated from the ideal (Bravo or Charlie according to modified United States Public Health Service USPHS criteria). All of them were recruited at the Operative Dentistry Clinic at the Dental School, University of Chile. The protocol was approved by the Institutional Research Ethics Committee of the Dental School at the University of Chile (project PRI-ODO-0207), and all patients signed an informed consent form and completed a registration form.

Treatment Group Criteria: 40 defective restorations were evaluated in accordance with the modified USPHS criteria. Restorations with clinically diagnosed secondary caries (Charlie) or under-contoured or over-contoured anatomic form defects and restorations with marginal defects (Bravo) were randomly assigned (Random Number Generator, Microsoft Excel 97) to either, the repair or replacement group. Diagnosis of active secondary caries was done according to Ekstrand's criteria 31.

The groups were labeled A: repair n= 19 (Class I n=8 and Class II n=11) and B: replacement n=21 (Class I n=9 and Class II n=12).

Restorations Assessment and Outcome Measurements. The quality of the restorations was scored according to the modified USPHS criteria (Table 1) 32. Two examiners underwent calibration exercises (JM and EF, Cohen's Kappa inter-examiner coefficient 0.74 at baseline and 0.87 at ten years). The examiners assessed the restorations independently by direct visual and tactile examination (mouth mirror, number 5, Hu Friedy Mfg. Co. Inc., Chicago, IL, USA, and explorer, number 23, Hu Friedy) and indirectly by radiographic examination (Bite Wing) at baseline (immediately after treatment) and 10 years after treatment. The seven examined parameters were marginal occlusal adaptation (MA), anatomic form (A), surface roughness (R), Marginal staining (MS), occlusal contact (O), secondary caries (SC), and luster (L) (Table 1). If any difference was recorded between the two examiners, and if they did not reach an agreement, a third clinician, who also underwent calibration exercises (GM), made the final decision.

Treatment Group