Effect of polishing burs and stones on the micro-hardness of dental amalgam.
Square standard cavities were prepared in human teeth and restored with amalgam obtained from alloys of different trade-marks. Twenty-four hours after condensation, excess amalgam was removed from three of the four margins, each with a different rotatory instrument (number 4 bur, multiblade finishing bur, and fine green stone). No rotatory instrument was used on the fourth margin (control), and this control was polished with pumice and zinc-oxide pastes and Sweeney's brushes. Vickers' tests for micro-hardness of the amalgam were performed on the four margins of the restorations. The restorations were then submitted to metallographic polishing, and a second micro-hardness measurement was made seven days later. The statistical analysis of the data showed that micro-hardness values were higher at the margins on which no rotatory instruments were used. The lowest micro-hardness values were found at the margins where finishing and/or round burs were used. Polishing with fine green stones gave intermediate values.
Ribeiro
S A
SA
Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Brasil.
do Nascimento
T N
TN
Centola
A L
AL
Teixeira
L C
LC
Campos
S M
SM
D000704:Analysis of Variance; D003723:Dental Amalgam / Q000737:chemistry*; D003775:Dental Polishing / Q000295:instrumentation*; D003793:Dental Restoration, Permanent; D006244:Hardness; D006801:Humans
D003723:Dental Amalgam