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Biomedical subjects

S A Ribeiro

Publications and source records attributed to S A Ribeiro.

8 recordsLinked to original sources
PubMed1992

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.

Analysis of Variance↗
PubMed1991

Effect of the polishing technique at low or high speed on the micro-hardness of dental amalgam.

Dental cavities were prepared and restored with amalgam, using three different silver alloys. The surface of the restorations was finished 24 hours after condensation, with a rotatory instrument using a low- or high-speed handpiece. The specimens were then submitted to metallographic polishing and one of the margins of the amalgam restoration were then submitted to Vickers' micro-hardness test. Another micro-hardness test was accomplished 168 hours after condensation and the two sets of micro-hardness values were compared. No significant statistical differences were detected between the micro-hardness values obtained with low or high speed in the polishing technique.

Dental Amalgam↗
PubMed1989

[Persistent alpha-vegetative state].

After briefly reviewing the concepts of "coma" and "alpha-coma", we report the case of a patient with presumable Pick's disease who spent several weeks in a vegetative state with a normal and reactive EEG in the alpha range in the later stages of her illness. We (a) emphasize some implications of the appearance of the eyes in such patients, b) stress the importance of distinguishing alpha activity from true alpha rhythm and (c) suggest the category "alpha-coma" should include only those individuals bearing evidence of disorders of the junctional tegmentum of the pons and midbrain. In a complementary way, we propose that patients in a persistent vegetative state displaying normal EEG should be separately classified as persistent "alpha-vegetative state".

Alpha Rhythm↗
PubMed1989

Bonnet syndrome and posterior parasagittal tumor: clues to neural mechanisms.

A case of Bonnet syndrome associated with blindness due to bilateral eye disease and a posterior parasagittal meningioma is reported. It is assumed that visual afferent deprivation alone is not enough to produce the syndrome and that, in most instances, a 'cerebral factor' must be operative if hallucinoses are to occur. The distinction between hallucinosis and hallucinations is favored and a common neural circuit for the mediation of hallucinotic imageries in general is suggested. One should not immediately put the blame on obvious eye or visual pathways affections when facing cases of Bonnet syndrome, as they are not likely to explain the complex array of images perceived by any given patient. On the contrary, the possibility of a clinically covert intracranial disease should be always raised and intensively looked for.

Aged↗
PubMed1987

[Orthostatic tremor].

Orthostatic tremor (TO) is a recently described new type of a high frequency irregular tremor which affects antagonistic sets of muscles in the lower limbs only since the erect posture is maintained. We describe two other cases of this peculiar kind of tremor which may be not so uncommon as up to now realized and emphatize its main diagnostic and semeiological characteristics. TO may share some basic pathophysiological mechanism with tremors of the classical heredofamilial essential variety.

Humans↗