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A G Vermeersch

Publications and source records attributed to A G Vermeersch.

18 recordsLinked to original sources
PubMed1979

Diametral tensile strength of twenty-three hardened commercial amalgams.

In view of the ever increasing number of high copper alloys, it was the aim of this study to investigate the tensile strength property of some of the new alloy systems. The factors alloy system and heat treatment were investigated in relation to the tensile strength. The factors alloy system as well as the heat treatment turned out to be significant. The study suggests that the introduction of "dispersion" alloys did not change the dental picture as to the property of the tensile strength. The selection of strength values in the range of 35-55 MN/m2 for the diametral tensile strength probably have no clinical relevancy as to the prevention of bulk fractures of amalgam restorations under oral conditions.

Copper↗
PubMed1976

[The tensile strength of amalgam after 15 minutes].

The authors are mainly interested in the investigation of the tensile strength of a setting amalgam acquired after 15 minutes after the end of the trituration. Knowledge about this property is of interest because generally this moment corresponds with the time that a patient is asked to put the amalgam restoration into contact with the antagonist tooth. In two series of experiments eight commercial amalgam alloys, two different trituration techniques (hand and Silamat mixing machine) as well as two condensation techniques (hand and Bergendal vibrator) were tested. The reslts reveal that the tensile strengths of the different treatment combinations of amalgams prepared from Dispersalloy are significantly much higher than the minimum value of 2 MN/m2 which is required by the new stipulations of the A.D.A. specification n degrees 1. Some amalgams do not satisfy this requirement. Although the influence of the trituration technique as well as that of the condensation technique turns out to be significant, apparently the influence of the amalgam alloy is of much greater importance.

Dental Amalgam↗
PubMed1976

[Resistance to traction forces in different brands of amalgam].

In a previous study the initial tensile strength of several dental amalgams after 15 minutes has been investigated. The present study scrutinized a large number of dental amalgams for the tensile strength after 15 minutes up to 60 minutes. All the dental amalgam specimens used in this study were prepared according to A.D.A. specification no. 1. The results obtained from this study show that out of the twenty three dental amalgams only approximately the half conformed to the minimum value of 2.0 MN/m2 as required for the tensile strength after 15 minutes by A.D.A. specification no. 1. Contrary to the results obtained by other investigators, the dental amalgam obtained from the spherical type of alloys does not acquire a superior initial strength in comparison with those from the conventional types of amalgam alloys. In this study the new dental amalgam alloy Indiloy (n.z.) (Shofu Corporation, Japan) demonstrated a superior tensile strength for all the testing times. If the tensile strength after 15 minutes is taken as a selection criterion, the five best alloys in this investigation are Indiloy (n.z.), Optalloy II, Micro II, Revalloy and Cavex SF. If the previous study is considered likewise. Dispersalloy (fast setting form) should be taken into account as well.

Dental Amalgam↗
PubMed1975

[Restoration of hemi-arcades with amalgam].

As a rule should the half-mouth restorations in the frame of oral rehabilitation be done with gold inlays, overlays or full crowns. It is nevertheless possible to consider such restorations with amalgam and, providing that certain principles and technics and respected, such quadrant restorations could be valuable as well on the periodontal point of view as on the occlusal one. Regarding the periodontal point of view, it is now generally accepted that de restorations of the proximal aspects of the teeth have not to extend under the gingival margin. If this creates a risk for caries recurrences, still questionable, it eliminates the unavoidable periodontal lesions. Regarding the occlusal point of view, it is on the one hand difficult to build up a perfect occlusal restoration with a material which, on the moment the filling is completed acquires only a insufficient fraction of its final resistance. On the other hand it seems impossible to raise the occlusion in one or more teeth for the very same reason. The solution to this problem comprises a dubbel aspect. One has first of all to rebuild to the desired occlusal level the cavities of the whole quadrant with a temporary but resistant material wich allows at once a carefulness mastication. Polycarboxylate cement is suitable for this purpose. This temporary material is then replaced tooth after tooth in one or more sittings with amalgam. The second aspect of the solution consists in the use of amalgam wich acquires faster a sufficent resistance, allowing an ajustment of a perfect occlusion without the danger of fracturing it. Following the first estimates it seems that amalgam made of spherical particules and dispersed phase type alloys could meet with this requirements and bring an acceptable solution to our problem.

Bicuspid↗