MacGregor, A.R.

2018-01-31T11:47:26Z

2018-01-31T11:47:26Z

1965

Standard or stock impression trays have been used for over a century in the preliminary stages of the construction of full dentures, but no comprehensive study of their design in relation to the size and form of the dentulous and edentulous jaws could be found in the literature, and none of the manufacturers of standard impression trays could supply biometric data on impression tray design.

The present study was undertaken because there appeared to be a need for further data on the subject.

Following the loss of teeth and the consequent resorption of supporting bone the facial contour changes, due to collapse of the lips and cheeks and alteration in the naxillo- mandibul jaw relationship. One of the objectives when making full dentures for edentulous persons is to attempt restoration of this facial contour. For this reason many clinicians have stressed that not only should the artifical teeth be placed in the positions formerly occupied by the natural teeth, but also that an adequate amount of denture base material should be used to replace the lost supporting bone and soft tissue (HOOPER 1934; FISH 1948; LANDA 1954.; SWENSON 1959; POUND 1960; LEE 1962; MARTONE 1963; BALLARD 1963).

In the preliminary stages of full denture construction, maxillary and mandibular impressions are taken for the purpose of recording the denture bearing areas of a mouth. They are taken with an impression material in impression trays and casts of the region are produced by pouring plaster of Paris or artificial stone into the impressions.

Many techniques have been described for taking impressions of the denture bearing areas of edentulous patients. These techniques have been reviewed by TUCKFIELD (1950), JAEGGI (1960), WOELFEL (1962) and others. Regardless of the technique employed, impression trays, known as standard or stock trays, are a prerequisite to securing a first or primary impression.

It is a common clinical experience that the size of an impression tray and its shape influences the shape and extent of the resultant impression taken with the tray. Thus an impression taken in a tray which is too small will not cover the denture bearing area, while an impression tray which is too large may cause an unnatural displacement of the surrounding lips and cheeks and of the vestibular sulcus which is composed of loose areolar tissue.

The designs of the impression trays in this study have been based on the principle that full dentures should replace lost tissue in such a way that the lips and cheeks are restored as far as possible to their pre -extraction contour, and that this restoration should begin at the first or primary impression stage.

AIMS OF THE PRESENT STUDY: i. To devise a method for measuring the size and form of the maxillary and mandibular denture bearing areas of the jaws of a selected sample of dentulous and edentulous human adults; ii. To apply these measurements to the design of standard impression trays for edentulous human adults.

http://hdl.handle.net/1842/28479

The University of Edinburgh

Annexe Thesis Digitisation Project 2017 Block 16

The size and form of dentulous and edentulous jaws, as related to the design of impression trays

Thesis or Dissertation

PhD Doctor of Philosophy