title: Amalgam restoration and in vitro caries formation.
abstract: Black's class I classic cavity preparations were completed in 124 extracted intact human premolars, of which 120 were restored with one of two silver amalgams, five different base combinations, and with or without cavity varnish. This resulted in 20 different restoration combinations. The other four teeth remained unrestored. Aging for 3 months and 1 year in 1% NaC1 at 20 degrees C followed. After aging, 80 of the restored teeth and the four unrestored teeth were subjected to an in vitro bacterial challenge for 36 days. The other 40 specimens were placed in an acidified (pH 4.0) broth for the same length of time. Sections were prepared for polarized light microscopy, and outer wall and dentin carious lesions were measured. The results were evaluated with one-way ANOVA and Tukey's Student range test with a critical level of statistical significance of p < 0.05 and p < 0.005. Lesions produced by bacterial challenge were significantly smaller than those formed by acidified broth. Aging time and varnish did not significantly influence lesion size. Low copper amalgam, a calcium hydroxide paste base, and restoration per se significantly reduced lesion size. Reproducible measurement of wall lesion length was not possible. Secondary caries lesion size can be minimized by judicious selection of restoration material combinations.
authors.affiliation: Dental Research Institute, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: E S
authors.initials: ES
authors.lastname: Grossman
authors.forename: J M
authors.initials: JM
authors.lastname: Matejka
mesh_terms: D000143:Acids; D000704:Analysis of Variance; D001641:Bicuspid; D002126:Calcium Hydroxide / Q000737:chemistry; D003300:Copper / Q000032:analysis; D003722:Dental Alloys / Q000737:chemistry; D003723:Dental Amalgam / Q000009:adverse effects / Q000032:analysis; D003731:Dental Caries / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D003736:Dental Cavity Lining; D003737:Dental Cavity Preparation / Q000009:adverse effects; D003743:Dental Enamel / Q000473:pathology; D003793:Dental Restoration, Permanent / Q000009:adverse effects; D003804:Dentin / Q000473:pathology; D004338:Drug Combinations; D005054:Eugenol / Q000737:chemistry; D005557:Formaldehyde / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008903:Minerals / Q000737:chemistry; D015203:Reproducibility of Results; D013295:Streptococcus mutans / Q000502:physiology; D013997:Time Factors; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D000143:Acids; D003722:Dental Alloys; D004338:Drug Combinations; D008903:Minerals; D005557:Formaldehyde; D005054:Eugenol; C025702:Dycal; D003300:Copper; D003723:Dental Amalgam; C003799:N2 Dental Cement; D002126:Calcium Hydroxide; D015034:Zinc Oxide