September 30th, 2008 by admin

An occlusion rim is a wax form used to establish accurate maxillo-mandibular jaw relations and arranging the artificial teeth to form the trial denture

Objectives of occlusal rims are to determine the approximate value for:

The occlusal vertical dimension
The necessarry degrees of lip support
The level and orientation of the occlusal plane
The most retruded relationship of the mandible to the maxilla
The occlusion rims simply replace the natural teeth both in dimension and their relationships to anatomic structures

The positing of the artificial teeth should not vary appreciably from that occupied by the natural teeth

Fabrication Technique and Dimensions of Occlusions Rims

A sheet of wax is heated over approximately 1/2 of its length with a Bunsen burner until the wax is soft
The wax is rolled at a point just short of the unheated area
It is then rolled and the process is repeated until a soft roll has been formed
The soft wax is adapted to a stick wax that was previously applied to the recording base

The rool is further sealed to the base using a wax spatula with additional molten wax

The edges of the roll are extended along the lateral surfaces to the border of the recording base
A heated plaster spatula is used to quickly shape the labial surface of the occlusion rim
The anterior surface should incline outward while the posterior surface is sloped slightly inwards
A hot wax spatula is used to smooth the lingual surface and form a rim approximately 5 mm wide in the anterior area and approximately 8 to 10 mm in the posterior area
The vertical height of the maxillary rim is adjusted to approximately 22 mm from the reflection of the cast
The posterior height is fabricated to equal the approximate lenght of the first maxillary molar crown, 18 mm.
The vertical height of the mandibular rim is about 16 mm in the anterior area while in the posterior region the height is equal to a point representing one half of the height of the retromolar pad