A clinical evaluation of polishing amalgams immediately after insertion: 36-month results.

Thirty-six patients, 7-13 years of age, demonstrated 96 pairs of contralateral occlusal fissure and bucca] and lingual pit cavities which were restored with a high-copper amalgam. One restoration in each pair was polished with a slurry of XXX-Silex in an unwebbed rubber cup at eight minutes following trituration. The contralateral restoration was finished with assorted pear-shaped Finishing burs and polished with a slurry of XXX-Silex, followed by a slurry of tin oxide. Each restoration was evaluated clinically by three examiners For five criteria which included modified Ryge clinical evaluation of marginal adaptation. Black and white photographs of each restoration taken at baseline and at six-month intervals for 36 months were evaluated using a modified Mahler method For assessment of marginal adaptation. Areas of marginal flash also were evaluated. Clinically, marginal adaptation became progressively more detectable for both groups from baseline up to 24 months, but there was no significant difference between the two different polishing methods during the 36 months. At baseline the surface texture of the restorations polished at eight minutes wits granular compared to the glossy surface of those polished at 24 hours, but by 36 months the surface texture of both groups was similar. The often maligned amalgam restoration is still the most commonly used dental restoration, even though claims persist that its longevity is limited?,2 The major reasons for the replacement of amalgams include recurrent decay and poor marginal adaptation. 2 While it is possible to control recurrent decay with a comprehensive preventive program, marginal adaptation is linked primarily to the physical properties and the manipulation of the amalgam. Improved marginal adaptation and reduced surface tarnish and marginal corrosion are among the purported benefits of finishing and polishing of amalgam restorations. ~ A period of at least 24 hours after insertion generally has been advocated for the finishing and polishing of conventional amalgams. However, it has been postulated that "immediate" polishing is possible for the newer high-copper amalgams because of improved physical properties such as faster setting time and earlier development of high compressive strength. 7-~ The aim of this study is to compare clinically for a three-year period the effects of polishing high-copper amalgam restorations at an interval of eight minutes after trituration with those finished and polished at least 24 hours after placement. Methods and Materials Thirty-three patients, age 7-13 years, who were selected for this study exhibited 66 contralateral pairs of Class I occlusal cavities and 30 pairs involving buccal or lingual pits. After administration of local anesthetic and tooth isolation with a rubber dam, the cavities were prepared with a #56 fissure bur utilizing high speed and restored with a high-copper amalgam (regular-set Tytina). 1° The restorations were designated by randomized assignment for either immediate polishing at eight minutes after the start of trituration, or finished and polished at 24 hours after insertion. The first method of polishing was accomplished during the operative appointment for one restoration of each pair at eight minutes after the start of trituration of the amalgam. A creamy mix of XXX-Silexb and water was applied with an unwebbed rubber cup in a slow-speed contra-angle handpiece to the restoration for a period of less than one minute per surface. The rubber cup was moved from the central fossa peripherally over the a S.S. White Dental Products International, Holmdel, N.J. b Moyco Industries, Inc., Philadelphia, Pa. 126 EARLY POLISHING OF AMALGAMS: Corpron et al. amalgam-enamel margins until the entire surface appeared clean and well defined. The second method designated that the other contralaterally paired restoration be finished and polished after at least 24 hours by a conventional method utilizing pear-shaped finishing burs, XXX-Silex, and tin oxide. 1° Two methods were used to evaluate the two techniques of polishing amalgams. The first method was a clinical examination by three examiners based on the modifed Ryge explorer examination. ~1q3 The criteria to be evaluated included marginal adaptation, surface texture (Tables 1 and 2), anatomic form, occlusal morphology, and caries. ~° The teeth were examined at baseline and at six-month intervals for a period of three years. The second method was a modification of that developed by Mahler 14 in which marginal adaptation was assessed from black and white photographs taken of each restoration at baseline, 6, 12, 18, and 36 months, and compared to photographs of six representative restorations depicting specific stages of marginal deterioration. 1° Additionally, the amount of marginal flash was assessed for each restoration: Category I -no flash, Category 2 -one or two areas of flash, Category 3 -three or four areas, Category 4 -more than four areas. A consensus for each evaluation was reached when at least two examiners agreed independently on the same rating for each clinical and for each photographic evaluation. If no consensus occurred, the three examiners reviewed the clinical or photographic scoring in order to reach a subsequent agreement.