43 . Pouring the Impression . LABORATORY3 . Pouring the Impression .
5Clinical Laboratory 2- Preliminary impression making *Pouring of impression to obtain the study cast *Construction of special (custom) trays
6Clinical Laboratory3 -Final impression.*Boxing and pouring of the final impression *Construction of recording bases and occlusion rims
7Clinical4-Recording of jaw relationships and selection of artificial teeth.
8DEFINITIONIt 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 ofa trial denture base &an occlusion rimtrial denture baseocclusion rim
9USES Of The OCCLUSION BLOCKS They help in1- Supporting the lips and cheeks to restore the contour of extraoral landmarks.
10Cont. Uses of The Occlusion Blocks 2-The orientation of the occlusal plane.
11Cont. Uses of the Occlusion Blocks 3- Determining the vertical dimension.
12Cont. Uses of the Occlusion Blocks 4-Recording the centric and eccentric jaw relations.
13Cont. Uses of the Occlusion Blocks 5- Selecting the size and position of the artificial teeth by the aid of the following markings :a- Midlineb-High lip linec- Canine line
14TRIAL DENTURE BASES (BASEPLATES) “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
16Cont. Trial Denture Bases Temporary trial denture bases1- Shellac base plate :It is commonly used because of its cost. It is adapted on the cast either by dry or moist heat.
17Cont. Trial Denture Bases Temporary trial denture bases2- acrylic resina-AutopolymerisingIt 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 :
18Cont. Trial Denture Bases Temporary trial denture bases3-Baseplate waxIt 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.
19Cont. Trial Denture Bases Temporary trial denture bases4- 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.
20Cont. Trial Denture Bases Temporary trial denture bases5- 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.
23OCCLUSION RIM“ 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 pumiceWax occlusion rim
24Method of construction of wax rims Cont. Occlusion RimMethod of construction of wax rims1- Ready made rims: by a device called occlusion rim former .2- Freehand molded rims: wax rolled and shaped to the arch form .