Chapter 5 Relief PDF

CHAPTER 5 Relief Chapter 5 Relief Definition: Relief is the elimination or reduction of undesirable forces or pressure from specific area under the denture base. Relief area: Relief area is the area in the fitt...

CHAPTER 5 Relief Chapter 5 Relief Definition: Relief is the elimination or reduction of undesirable forces or pressure from specific area under the denture base. Relief area: Relief area is the area in the fitting surface of the denture that is reduced to eliminate excessive pressure. Functions of relief: 1. Compensate for bone resorption. Since resorption occurs in the alveolar process, therefore relief of hard areas in the middle of the palate would enhance denture stability for a long period of time. 2. Compensate for technical discrepancies. Shrinkage of the base material during processing makes the upper denture slightly narrower across the tuberosities; so it should be relieved at the tuberosities to compensate for technical discrepancies. 3. Comfort for the patient. 57 CHAPTER 5 Relief Areas to be relieved: I- Hard bony areas. II- Sensitive areas. 1- Hard areas to be relieved: Since the mucous membrane overlying denture bearing area is not uniform in thickness, softness and resiliency, there is a tendency for a finished denture to rock upon hard areas under biting force. This can be compensated through relief of hard areas. Hard areas are located in the patient's mouth by inspection and palpation. In the maxilla, median palatine raphe and torus palatinus are hard areas to be relieved. (Fig.1) In the mandible, torus mandibularis, prominent genial tubercle, sharp mylohyoid ridge are hard areas to be relieved. Fig. 1 Relief of torus palatinus 58 CHAPTER 5 Relief II- Sensitive areas to be relieved: Sensitive areas are mainly relieved for patient's comfort. In the maxilla, incisive papilla, prominent tuberosities and rugea when enlarged. In the mandible, mental foramen and thin wiry ridge. Shape of the relief: According to the extent and depth of the hard or sensitive areas to be relived compared to the surrounding tissues we determine the shape of the relief. Methods of relief: I- Direct relief: It is achieved by either two ways: a- In case of elastic impression material, tin foil of desired thickness and shape is cut and sealed over the master cast. (Fig.2) 59 CHAPTER 5 Relief Fig.2 Direct relief II- Automatic relief: It is obtained at time of secondary impression, by providing space between the tray and the tissues to be recorded in some places than the other (selective pressure impression technique). 60