*Pouring of impression to obtain the study cast. *Construction of special (custom) trays 2- Preliminary impression making
3 -Final impression. * Boxing and pouring of the final impression *Construction of recording bases and occlusion rims
4-Recording of jaw relationships and selection of artificial teeth.
It is a combination of a base material, which accurately fits the cast (trial denture base ) and an arch shaped material occupying the space of the patient’s previous dentition (occlusion rim). It is therefore composed of a trial denture base & an occlusion rim trial denture base occlusion rim
They help in 1- Supporting the lips and cheeks to restore the contour of extraoral landmarks.
2-The orientation of the occlusal plane.
3- Determining the vertical dimension.
4-Recording the centric and eccentric jaw relations.
5- Selecting the size and position of the artificial teeth by the aid of the following markings : a- Midline b-High lip line c- Canine line
“Part of the occlusion block that rests on the supporting structures and carries the occlusion rim. “ Requirements: They should : 1- fit the cast accurately. 2-rigid and strong to withstand the biting force. 3-be dimensionally stable. 4-stable inside the patient’s mouth. 5 smooth and clean to avoid patient’s discomfort. 6-be of proper thickness (2mm on the palate & less on the alveolar crest). 7-be easily and quickly constructed. trial denture base
Types Temporary 1- Shellac 2- Autopolymerizing and light cured acrylic resin 3- Vacuum formed vinyl or polystyrene 4- Baseplate wax 5- Swaged tin Permanent 1- metallic gold alloys cobalt chromium alloys 2- non-metallic heat cured acrylic resin
Temporary trial denture bases 1- Shellac base plate : It is commonly used because of its cost. It is adapted on the cast either by dry or moist heat.
Temporary trial denture bases 2- acrylic resin a-Autopolymerising It is either mixed and adapted on the cast or it is sprinkled on it. It offers rigidity, close adaptation and can withstand heat and pressure without deformation. b- Light cured resin :
Temporary trial denture bases 3-Baseplate wax It is easily adapted and can be thinned to gain space to set the teeth. However, it lacks dimensional stability since it cannot withstand biting pressure and body temperature.
Temporary trial denture bases 4- Swaged tin : Three layers of swaged tin adapted on a metal die of the master cast and cemented together by a thin film of hard wax. It is accurate, dimensionally stable at mouth temperature and provides uniform thickness of the final denture.
Temporary trial denture bases 5- Vacuum formed vinyl : Preformed sheets adapted by vacuum. It provides a fast, rigid and accurate record bases. However, it needs expensive equipments and is difficult to trim.
“ They are occluding surfaces fabricated on temporary or final denture bases to record the maxillomandibular relation and to arrange teeth. They simulate the space occupied by the natural teeth and the related structures.” Material of construction : 1- Wax : most commonly used. 2- Modeling plastic 3- Plaster and pumice Wax occlusion rim
Method of construction of wax rims 1- Ready made rims: by a device called occlusion rim former. 2- Freehand molded rims: wax rolled and shaped to the arch form.