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Biomedical subjects

P Gateau

Publications and source records attributed to P Gateau.

At least 19 recordsLinked to original sources
PubMed2001

In vitro fatigue resistance of glass ionomer cements used in post-and-core applications.

STATEMENT OF PROBLEM: New glass ionomer cements exhibit better mechanical properties than their older counterparts. However, there is concern about their use as a core material in post-and-core applications. PURPOSE: This in vitro study evaluated the fatigue resistance of 2 new glass ionomer cements, Shofu Hi-Dense and Fuji IX GP, and compared their mechanical behavior as a core material under masticatory load with a silver-reinforced glass ionomer (ESPE Ketac-Silver) and a silver amalgam (Cavex Avaloy LC). MATERIAL AND METHODS: A total of 100 commercial plastic teeth were divided into 4 groups of 25 specimens each. Titanium posts were placed in the prepared root canals, and cores were built up in amalgam, silver-reinforced glass ionomer cement, and the 2 new glass ionomer cements. The post-and-core specimens were prepared for full cast metal crowns, which were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator and cyclically loaded with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. The specimens were sectioned and observed macroscopically and microscopically to determine the number of defects (alterations) in each material. Observed defects were verified with the Kruskal-Wallis test, and the 4 core materials were ranked with the Tukey multiple comparisons test. RESULTS: The mean rank sum values of the defects were as follows: Cavex Avaloy LC Amalgam (16.75), Fuji IX GP (38.50), Shofu Hi-Dense (39.53), and ESPE Ketac-Silver (67.22). The amalgam alloy was significantly different (P< .05) from the others. CONCLUSION: Under the conditions of this study, the 2 new glass ionomer cements used as core materials showed a higher number of defects than amalgam. These results suggest that their fatigue resistance may be inadequate for post-and-core applications.

Cermet Cements↗
PubMed2001

The double-inlay technique: a new concept and improvement in design.

Gold and ceramic have long been used in prosthetic dentistry. In the posterior region, it is possible to use both materials with the double-inlay technique to add the strength of metal to the esthetics of ceramic. The problem, however, remains the volume of tooth reduction required to avoid ceramic fracture. This article describes a modification of the double-inlay technique that makes use of a pin system. This modified technique permits good retention while avoiding excessive tooth reduction.

Adult↗
PubMed1999

Fatigue testing and microscopic evaluation of post and core restorations under artificial crowns.

STATEMENT OF PROBLEM: Coronoradicular reconstruction techniques of pulpless teeth include prefabricated post systems that retain a core material such as silver amalgam, composite, glass ionomer, or modified glass ionomer cement. Mechanical properties of these materials are critical to sustain masticatory forces. PURPOSE: This in vitro study compared the mechanical resistance of 3 core materials (silver amalgam, composite, and silver-reinforced glass ionomer) under masticatory conditions. MATERIAL AND METHODS: Industrially fabricated teeth were used and a total of 75 specimens were divided into 3 groups of 25 specimens. Titanium canal posts were placed, followed by core buildups in amalgam, composite, or glass ionomer. Teeth were prepared for full cast crowns and the crowns were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator cyclically loading the teeth with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. Teeth were sectioned and observed macroscopically and microscopically to determine the rate of defects for each material. Observed defects were verified with the Kruskal-Wallis test. The 3 core materials were ranked with the Tukey multiple comparison test. RESULTS: Significant differences of mechanical behavior were found for the 3 materials. At P <.01, silver amalgam was significantly superior to composite and glass ionomer. Composite was significantly superior to glass ionomer. CONCLUSION: Cores fabricated with amalgam had the lowest rate of defects when tested under artificial crowns. Glass ionomer, when used as a core material under artificial crowns, showed the highest rate of defects after an instantaneous load of 400 N for a 1,500,000 repetition cycle.

Biomechanical Phenomena↗
PubMed1983

[Fibrinolytic treatment of valve thrombosis. Apropos of 16 cases].

Sixteen cases of prosthetic valve thrombosis (9 mitral, 5 aortic), occurring in 14 patients, were treated by fibrinolysis. All were disc prostheses. The clinical state of the patients was very poor in 11 of the 16 cases with pulmonary oedema, low output and arrhythmias, but less dramatic in the 5 others who presented with thromboembolism and left ventricular failure. The diagnosis was made by echocardiography (9 cases), radio-cinema of the valve (9 cases) and/or angiography (4 cases). The therapy comprised Urokinase (UK) 4,500 U/kg/hour (6 cases) of Streptokinase (SK) 2,000,000 U in 10 hours (7 cases) or SK and UK at equal doses (3 cases). The outcome was assessed clinically, echocardiographically and radiologically. There were 11 definite successes, 2 partial improvements requiring surgical revision, 2 apparent successes but with massive recurrence at the 7th and 10th days, and 1 failure. Although the biological activity of SK is greater than that of UK, the clinical results were comparable with both fibrinolytic agents. Four patients had regressive embolic episodes during lysis of the valvular thrombosis. As fibrinolytic therapy was effective in 70 p. 100 of patients in this series, it could provide an acceptable alternative to surgery, especially in patients who would be poor operative risks. The management of patients after successful fibrinolysis remains divided between intensive medical follow-up or prosthetic valve replacement.

Adult↗
PubMed1983

Diagnosis of dissecting aortic aneurysm by two dimensional echocardiography: experience with 58 patients.

UNLABELLED: Recent improvements in surgical technics have dramatically changed the outcome of patients with aortic dissection (AD). The aim of this work is to evaluate the reliability of two dimensional echocardiography (2DE) in the diagnosis of AD. The 2DE was recorded in all patients with a systematic approach in order to visualize the entire aorta (Ao). 58 cases were studied in a three years period. At the beginning of this study we validate 2DE by comparison with angiography (angio) in 14 of our first patients: the 2 angio criteria (dilatation, abnormal intraluminal image) have been found on 2DE in 12 pts (92%), with intraluminal image) have been found on 2DE in 12 pts (92%), with no significant difference between internal diameter of Ao on angio and 2DE. In our experience with 58 pts a positive diagnosis was possible in 90% of AD type I and only 18% of AD type III. IN CONCLUSION: 2DE is a practical and valuable method for the assessment of type I and II AD. Two 2DE criteria must be present at the same anatomical level (dilatation, abnormal intraluminal echo). In these conditions we have been able to avoid aortography in 26 of our last patients with type I and II.

Adult↗
PubMed1981

[Hemodynamic effects of percutaneous trinitrin].

The haemodynamic effects of nitroglycerin (NG) ointment were studied in 13 patients, 6 with congestive cardiac failure. After two basal measurements 30 minutes apart, heart rate (HR), right atrial pressure (RAP), pulmonary artery diastolic pressure (PADP), mean systemic arterial pressure (MAP) and cardiac index (CI) were measured every fifteen minutes for one hour, and every hour for five hours. Two patients were given one capsule, and nine patients two capsules of 10 mg NG, applied on separate 15 cm2 skin patches and covered with plastic dressings. There was a slight fall of 1,9% in HR from the 45th minute to the 5th hour. A large increase in HR was only observed in one patient who had low basal filling pressures. A moderate decrease in MAP was recorded (4,6%, p less than 0,05) The greatest changes were observed in RAP which decreased (p less than 0,05) from the 30th to the 60th minute with a maximum at the 45th minute (17,4%) and in PADP which fell from the 15th minute to the 5th hour (p less than 0,005) with a maximum at the 120th minute (21,9%). Local tolerance was good. The systolic blood pressure did not fall below 90 mm Hg in any patient. A case by case analysis showed falls of RAP and PADP of over 20% in 10 and 9 patients respectively. The decrease in PADP was not proportional to the basal value but patients with the highest initial values had the least changes. A 20% fall in PADP was observed in only one of four patients with PADP of over 25 mm Hg at rest. A greater dose of NG might have had a greater effect in these patients. There was no significant change in CI, probably due to the stability of peripheral arterial resistances during the study. The value of this preparation of NG lies in its long duration of action. A fall in PADP of over 15% was observed up to the 150th minute, and persisted to a lesser degree up to the 5th hour. This makes it very suitable for the treatment of nocturnal angina as conventional antianginal delayed release nitrate derivatives usually have a shorter duration of action.

Adult↗
PubMed1976

Passive immunotherapy in HBs Ag fulminant hepatitis. Results on antigenaemia and survival.

19 patients with HBs Ag-positive fulminant hepatitis underwent exchange transfusions and anti-HBs-rich plasma infusions. Circulating HBs Ag disappeared in 17 cases. Circulating anti-HBs detected by RIA was higher in cases with liver regeneration. There was no correlation between circulating anti-HBs level and the amount of anti-HBs-rich plasma administered. Recovery was observed in 36% of the cases and liver regeneration in 47%. As the beneficial effect of such a treatment is not yet evident, a controlled trial should require pairing of patients with respect to the number of exchange transfusions and amount of real or placebo anti-HBs.

Adolescent↗
PubMed1975

[Encephalopathy in acute hepatic atrophy. Effect of the purification of middle molecules. Preliminary results].

The authors have achieved 5 complete recoveries from coma and two partial recoveries in 9 non-decerebrate patients in coma due to acute hepatic atrophy by using polyacrylonitrile membrane haemodialysis. Survival was not possible until sufficient hepatic regeneration had developed. On the other hand, repeated returns to consciousness were observed with prolonged survival lasting up to 40 days despite almost complete destruction of the liver. The different hypothesis relating to the mechanism of the encephalopathy and the usefulness of such a procedure are discussed: filtration of ammonia, free fatty-acids, role of amino-acids and possible polypeptides.

Adult↗