Posterior Palatal Seal PDF

Posterior Palatal Seal Palatal Seal (PPS) Definition: Soft tissue along the junction of hard and soft palates On which, pressure within physiologic limits are applied here by the prosthesis to aid in retention of the denture Posterior Seal A Good posterior seal helps: o Reducing the gag reflex o Pre...

Posterior Palatal Seal Palatal Seal (PPS) Definition: Soft tissue along the junction of hard and soft palates On which, pressure within physiologic limits are applied here by the prosthesis to aid in retention of the denture Posterior Seal A Good posterior seal helps: o Reducing the gag reflex o Prevents accumulation of food between posterior part of denture and soft palate o Reduces patient discomfort when wearing the denture o Makes up for shrinkage of acrylic that occurs during processing A properly placed posterior palatal seal: o Should not impinge tissues of hard palate o Should not limit the movements of the soft palate Clinical Importance of Posterior Palatal Seal o Retention/Stability come from: § ADHESION § COHESION § INTERFACIAL TENSION o Resists dislodging forces directed at R angles to denture base § Helps resist vertical forces The posterior palatal seal lies between these two lines Clinical Importance of Good Border Sealing Retention and stability Resistance to vertical forces Good border seal resists horizontal and rotational forces Max denture: o Posterior border located in posterior palatal seal = best results o Maintains contact w tissues of anterior soft palate o Establishes border seal and helps denture retention Vibrating Lines An imaginary line across the posterior part of the palate Marks the division btwn the movable and immovable tissues of the soft palate Identified when the movable tissues are functioning 2 Vibrating lines: o Anterior o Posterior Posterior palatal seal sits btwn the vibrating lines There are two vibrating lines: anterior and posterior Anterior Vibrating line Sits at junction of ATTACHED tissue overlying hard palate and the immediate MOVABLE tissue of soft palate It is ALWAYS on soft palate Due to the projection of the posterior nasal spine, the anterior vibrating line is NOT a straight line o Takes the shape of a cupid’s bow. Line located via Valsalva Maneuver o Pt is asked to blow gently through nose with both nostrils closed o During this process, soft palate gets placed inferiorly at the junction of the hard and soft palate (junction marked with an indelible pencil) o It can also be visualized by asking the patient to say ‘ah’ forcefully in short bursts. Posterior Vibrating Line Sits at junction of APONEUROSIS of the tensor veli palatini muscle and musculature of SOFT PALATE It is the demarcation btwn part of soft palate that has limited movement during function and the remainder of the soft palate that is markedly displaced during function It is a slightly curved line Located by asking pt to say ‘ah’ normally, unexaggerated way in short bursts. This line marks the distal most extension of the denture base The Arbitrary Posterior Palatal Seal Placement of Arbitrary Posterior Palatal Seal Accomplished AFTER Master Cast has been trimmed and dried Mark anatomical structures that determine posterior length/edge of denture o Fovea palatini at midline o Hamular notch on either side of posterior border Posterior border of palatal seal determined from A-line or vibrating line which was determined from pt Example: A line located ~1mm posterior to fovea palatini in the midline, extends to the hamular notch on either side. Draw posterior border where we want the denture and post dam area to be. Notice it goes to the hamular notch area, but it does NOT go through the notch. Anterior portion of posterior palatal seal in midline is at least 3-4 mm anterior to posterior limit and should blend down laterally to the posterior border Posterior Palatal seal is then scribed by the use of a #8 round bur on straight handpiece The depth of the of the line is approximately 1/2 depth of #8 round bur Scribe this line from midline to hamular notch area Use a vulcanite scraper or the round end of a # 7 wax spatula o Blend/round off edges of this line that we have scribed o Blended from scribed line to posterior area AND from scribed line to anterior limit of posterior area The arbitrary posterior palatal seal has now been completed The baseplate is checked to make sure it is NOT OVEREXTENDED at posterior border An acrylic bur is used to adjust the baseplate until it coincides with posterior edge of posterior palatal seal. Review: Mid portion of posterior palatal seal is 1/2 thickness of # 8 round bur from mid portion to the posterior border into the anterior border Scraped w a vulcanite scraper or round end of # 7 spatula until these blend with tissue of master cast along the outline of post dam. If maxillary base plate is already fabricated, it can now be modified with wax in the posterior palatal seal area If fabricating base plate AFTER creating space in master cast, it will take the shape of the posterior palatal seal that was just created in the cast.