PPS PROSTHODONTICS

posterior palatal seal prostho

1. SEMINAR ON- POSTERIOR PALATAL SEAL Guided By : Dr. Manesh Lahori Dept . of Prosthodontics PRESENTED BY Dean & Head Dr C Pradeep K.D.D.C PG STUDENT

2. INTRODUCTION DEFINITION BOUNDARIES FUNCTIONS ANATOMIC AND PHYSIOLOGIC CONSIDERATION RATIONALE FOR PLACEMENT OF SEAL IN IMPRESSION TRAY PLACEMENT TECHNIQUE TROUBLESHOOTING CONCLUSION CONTENTS

3. INTRODUCTION The diagnostic evaluation and placement of the posterior palatal seal is of great importance. The posterior border of maxillary denture has definite anatomic and physiologic boundaries ,once understood, make the placement of the posterior palatal seal a quick and easy procedure with predictable result

4. DEFINITION Acc. to GLOSSARY OF PROSTHODONTIC TERMS-9 POSTERIOR PALATAL SEAL :That portion of the intaglio surface of maxillary removable complete denture , located at its posterior border, which places pressure, within physiologic limits, on the pps area of the soft palate ;this seal insures intimate contact of the denture base to the soft palate and improves retention of the denture POSTERIOR PALATAL SEAL AREA: The soft tissue area limited posteriorly by the distal demarcation of the movable and nonmovable tissues of the soft palate and anteriorly by the junctionof the hard and soft palates on which pressure, within physiologic limits, can be placed; this seal can be applied by a removable complete denture to aid in its retention.

5. BOUNDARIES OF THE POSTERIOR PALATAL SEAL AREA ANTERIORLY-Anterior vibrating line POSTERIORLY-Posterior vibrating line LATERALLY- Pterygomaxillary notch Anterolaterally extented ahead of hamular notch Superoinferiorly – soft palatal tissues

6. BOUNDARIES OF THE POSTERIOR PALATAL SEAL AREA VIBRATING LINE-“The imaginary line across the posterior part of the palate marking the division between the movable and immovable tissues of the soft palate which can be identified when the movable tissues are moving”

7. ANTERIOR VIBRATING LINE It is an imaginary line located at the junction of the attached tissues overlying the hard palate and the movable tissues of the immediately adjacent soft palate. This line can be located by having the patient perform the “valsalva maneuver”.

8. ANTRIOR VIBRATING LINE The anterior vibrating line can also be approximated by visualizing the area while the patient says “ah” in short vigorous bursts. The anterior vibrating line is ‘cupid bow’ shaped.

9. POSTERIOR VIBRATING LINE It is an imaginary line located at the junction of soft palate that shows limited movement and the soft palate that shows marked movement. It also represents the junction of aponeurosis of Tensor veli palatine muscle and the muscular portion of soft palate.

10. POSTERIOR VIBRATING LINE The posterior vibrating line can be visualized by instructing the patient to say “ah” in short bursts in a normal unexaggerated fashion. This line marks the most distal extension of the denture base.

11. FUNCTIONS OF POSTERIOR PALATAL SEAL The primary purpose of the posterior palatal seal is the retention of the maxillary dentures. A properly developed PPS will help reduce the gag reflex. Reduce food accumulation beneath the posterior aspect of the denture due to proper utilization of tissue compressibility.

12. FUNCTIONS OF POSTERIOR PALATAL SEAL Reduce patient discomfort when contact occurs between the tongue and the posterior end of the denture base . Will compensate for the volumetric shrinkage that occurs during the polymerization of methylmethacrylate resin.

13. ANATOMIC AND PHYSIOLOGIC CONSIDERATIONS The posterior palatal seal is divided into two separate but confluent areas based upon anatomic boundaries. The postpalatal seal The pterygomaxillary seal

14. ANATOMIC AND PHYSILOGIC CONSIDERATION POSTPALATAL SEAL-This is a part of the posterior palatal seal that extends between the two maxillary tuberosities while, PTERYGOMAXILLARY SEAL-This is the part of posterior palatal seal that extends across the hamular notch and it extends 3 to 4 mm anterolaterally to end in the mucogingival junction on the posterior part of maxillary ridge.

15. THE POSTERIOR PALATAL SEAL AREA

16. PHYSIOLOGICAL CONSIDERATION OF POSTERIOR PALATAL SEAL AREA Pterygomaxillary notch Pterygomandibular fold The hamular process The fovea palatine The median palatal raphe Midpalatal fissure

17. PHYSIOLOGICAL CONSIDERATION OF POSTERIOR PALATAL SEAL AREA Pterygomaxillary notch-is a depression situated between maxillary tuberosity and hamulus of medial pterygoid plate The tissues in this region can be safely displaced to achieve posterior palatal seal

18. PHYSIOLOGICAL CONSIDERATION OF POSTERIOR PALATAL SEAL AREA PTERYGOMANDIBULAR FOLD extends from the posterior aspect of tuberosity postero-inferiorly to insert into the retromolar pad. Hamular notch is covered by pterygomandibular fold

19. PHYSIOLOGICAL CONSIDERATION OF POSTERIOR PALATAL SEAL AREA HAMULAR POCESS is located 2 -4 mm posteromedial to the distal limit of the maxillary residual ridge Covered by a thin layer of mucous membrane The hamular processes should never be covered by the denture

20. PHYSIOLOGICAL CONSIDERATION OF POSTERIOR PALATAL SEAL AREA FOVEA PALATINA is formed by collection of ducts of several mucous glands They are not constant findings in every individual,however,they are unique to humans It act as an arbitrary guide to locate the posterior border of the denture

21. RATIONALE FOR PLACEMENT OF SEAL IN IMPRESSION TRAY To establish positive contact posteriorly to prevent the final impression material from sliding downs the pharynx. To serve as a guide for positioning the impression tray To create slight displacement of the soft palate To determine if adequate retention and seal of the potential denture border is present.

22. CLASSIFICATION OF SOFT PALATE Based upon the angle that soft palate makes with the hard palate Class I – Soft palate is rather horizontal as it extends posteriorly with minimal muscular activity Class III –Most acute contour in relation to the hard palate,marked elevation of musculature to create velopharyngeal closure. Class II – palatal contour lie between Class I and ClassIII

23. Types Of Posterior Palatal Seal Area According To Shape: BEAD ON CAST : Single bead at the distal margin of the denture. DOUBLE BEADED : One bead at the distal margin and other at anterior aspect of the palpated posterior palatal seal area.

24. BUTTERFLY SHAPED: Deepest at the most compressible area of the posterior palatal seal area. It merges gradually with its anterior and posterior borders. BUTTERFLY SHAPED

25. BUTTERFLY SHAPED WITH BEAD ON DISTAL EDGE OF DENTURE: Deepest part lies at the distal most part of posterior seal area,in the form of bead.

26. BUTTERFLY SHAPED WITH WIDENED POSTERIOR PALATAL SEAL IN EACH HAMULAR NOTCH REGION: More wide in each of the hamular notches . Studies done by the workers shown that altering the type of posterior palatal seal affects the retention.None of the type is tested proved to be superior.

27. ACCORDING TO THE AREA COVERED Posterior palatal seal can generally be extended to about 4 mm from the distal border of the denture. In hamular notch areas it may be narrow down to 2 mm. Silverman advocates that denture can be extended to an average of 8.2 mm dorsally to the “flexion line”.

28. House modification class I: flat modified butterfly with the maximum antero -posterior width 3-4 mm class II: high modified butterfly,2-3 mm with the maximum antero -posterior width 2-3 mm. class III: intermediate a bead type- minimum width at posterior palatal spine.

29. PLACEMENT TECHNIQUE The techniques used to mark posterior palatal seal are: 1. Conventional technique 2. Fluid wax technique 3. Arbitrary scrapping of the master cast 4. Extended palate technique 5. PPS on master cast ( other methods) 6 . Adding PPS to an existing denture

30. CONVENTIONAL TECHNIQUE After an accurate and fully extended final impression has been made and poured, a well adapted resin tray is fabricated on the stone cast. The posterior palatal seal area is first dried with a gauge and then a T-burnisher is used to palpate the hamular process

31. CONVENTIONAL TECHNIQUE The anterior and posterior vibrating lines are then marked using an indelible pencil. The resin or shellac tray is then inserted in the mouth and seated firmly to place. Upon removal from the mouth, the indelible lines should have been transefered to the tray. The tray is then returned to the master cast to transfer the line.

32. CONVENTIONAL TECHNIQUE A kinsley scraper is then used to scrap the cast. The deepest areas of the seal are located on eitherside of midline, one-third the distance anteriorly from the posterior vibrating line. It is scraped to a depth of approximately 1 to 1.5 mm.

33. CONVENTIONAL TECHNIQUE In the area of the median palatal raphe; the cast is scraped to a depth of 0.5-1 mm If the shellac tray is used, it is then replaced on the moistened master cast, reheated and readapted to conform to the scored palatal seal area. After the tray has cooled, it is placed back in the patient’s mouth and its retentive qualities are evaluated.

34. ADVANTAGES The trial base will be more retentive, which can produce more accurate maxillomandibular records. Patients will be able to experience the retentive qualities of the trial base giving them the psychological security. The dentist will be able to understand the retentive qualities of the finished denture The posterior extension of the denture can be understood by the patient.

35. DISADVANTAGES It is not a physiological technique and so depends upon the accurate transfer of vibrating lines and careful scraping of the cast. The potential for overcompression of the tissue is great.

36. FLUID WAX TECHIQUE The fluid wax technique is similar to the conventional technique except that in this technique the indelible transfer markings are recorded on the final wash impression. Corrective wax is used in this technique.

37. PROCEDURE The wax is melted and painted on to the impression surface within the outline of the seal area. The wax is then allowed to cool slightly below the mouth temperature to increase its consistency and to make it more resistant to flow. The impression is carried to the mouth and held under gentle pressure for 4-6 minutes to allow time for material to flow.

38. The melted wax is painted onto the final impression within the outline of the posterior palatal seal area

39. After 4-6 mins the impression is removed from the mouth and the wax is examined for uniform contact. The secondary impression is reinserted and held for 3-5 mins under gentle pressure followed by 2-3 minutes of firm pressure applied to the midpalatal area of the impression tray. Final impression is then boxed and poured

40. Upon removal from the mouth wax that extended beyond the posterior palatal seal area has been trimmed

41. ADVANTAGES It is a physiologic technique displacing tissues within their physiologically acceptable limits. Overcompression of the tissues is avoided Posterior palatal seal is obtained increasing retention Mechanical scraping of the cast is avoided.

42. DISADVANTAGES More time is needed.It is a time consuming process Difficulty in handling the material

43. ARBITRARY SCRAPING OF THE MASTER CAST In this technique the anterior and the posterior vibrating lines are visualized by examining the patient’ mouth and approximately marked on the master cast. 0.5-1 mm of stone is scraped in the posterior palatal seal area of the master cast and the denture is fabricated This technique is inaccurate and not physiological and should be avoided.

44. EXTENDED PALATAL TECHNIQUE Described by Silverman in 1971. In this technique, the denture border is extended 8.2 mm beyond the anterior vibrating line. This method is not widely used currently.

45. Determining PPS on Master Cast The second commonly reported technique is locating and transferring the PPS area on the master cast followed by subsequent scrapping . The scraping of the PPS on the cast allows the seal area to have a convex surface on the denture that slightly displaces the soft palate thereby achieving peripheral seal. Some of the techniques of scrapping and designs of PPS are explained here. All of these scoring techniques are done after correctly transferring the PPS area on the master cast.

46. Boucher’s Technique Stage of recording: before Jaw relation record: Posterior vibrating line is located and transferred on the master cast Temporary denture base is reduced to this line ‘V’ shaped groove is scraped 2mm anterior to the line According to Boucher narrow bead like seal is more effective

47. Bernard Levin’s Technique For class III soft palate forms: He describes a ‘double bead’ technique for class III soft palate . Here, the posterior vibrating line is scrapped 1 mm deep and 1.5 mm wide. An anterior bead line is created about 3 to 4 mm from the posterior border . This is considered as the ‘rescue bead’. Bernard stated that even though the anterior bead is located on the hard palate, the keratinization of the mucosa can tolerate small amount of tissue displacement and pressure.

48. Bernard Levin’s Technique For class I and class II soft palate forms: Using No. 8 round bur of 2 mm diameter, two holes of 2 mm depth are drilled at the depth of the bur in the area between the midline and hamular notches . One hole of 1 mm depth is drilled to half the diameter of the bur in the center . A cone-shaped acrylic resin g bur is used to rough out the seal.

49. The hamular notch region is not reduced more than 0.25 mm in width and 0.5 mm in depth and not extended onto the tuberosity vestibules . The softest part of the seal is scraped to 6 mm in width, whereas the median raphe region is scraped to 4 mm in width. A medium grid sand paper is used to smooth the surface.

50. : PPS designs with the cross-sectional views depicted in wax: (A) Single bead (Boucher’s technique) and (B) double bead (Bernard Levin class III technique)

51. Swenson’s Technique A groove is cut along the posterior line to a depth of 1 to 1.5 mm that will cause the posterior border stand straight out from the hard palate, turning neither up nor down . From the depth of this posterior cut, the cast is scraped in a tapering manner , so that it tapers up to the anterior line.

52. Calomeni , Feldman, Kuebker’s Technique A posterior bead line is scraped on the cast to a depth of 1 to 1.5 mm extending bilaterally through the hamular notches . The anterior line is placed 5 or 6 mm anterior to the posterior line. The area between the anterior and posterior lines is scraped with Kingsley Scraper No 1. The depth of the cast scraped should vary from zero at the anterior line to the depth of 1 to 1.5 mm along the posterior border. In the midline, the distance between the anterior and posterior lines should be about 2 to 3 mm.

53. : PPS designs with the cross-sectional views depicted in wax : (A) Butterfly (Swenson technique) and (B) butterfly with bead ( Calomeni technique)

54. Pound’s Technique Pound advocates a single bead posterior palatal seal with anterior extensions for additional air seal . A ‘V’- shaped groove is carved across the palate from the hamular notch to hamular notch 1 to 1.5 mm wide and 1 to 1.5 mm deep. This is placed 2 mm anterior to vibrating line. A loop is carved on either side of the midline to provide air seal. The depth and width of the anterior loop are determined by palpating the area with a blunt end of the instrument.

55. Apple Baum-Winkler’s Technique A Kingsley scraper is used to score the cast . The deepest parts of the seal are located on either side of the midline, one-third distance anteriorly from the posterior vibrating line. It is scraped to a depth of 1 to 1.5 mm. Close to mid-palatine region , the area is scraped to a depth of 0.5 to 1.0 mm as it has little submucosa and cannot withstand the same compressive forces as tissues lateral to it. The scraping is gradually feathered out as it approaches the anterior vibrating line and is tapered toward the posterior vibrating line. The posterior palatal seal resembles , like Cupid’s bow.

56. (A)Pound’s technique and (B) Winkler’s technique of PPS designs with the cross-sectional views depicted in wax

57. Silverman’s Technique A pencil line is inscribed from hamulus to hamulus midway between the anterior and posterior flexion lines . A shallow scratch mark is placed on the anterior flexion line and the posterior flexion line is scored to a depth of one half of that of the midscore line. The cast is scraped over the entire seal area . The depth of the cast scraping diminishes from the midline to the anterior and posterior vibrating lines . He also suggested that complete maxillary dentures can be extended on an average distance of 8.2 mm dorsally to the vibrating line

58. Hardy and Kapur Technique1 The depth of the posterior palatal seal area is identified by pressing the ball portion of the T burnisher . The posterior palatal seal is extended 4 mm from the distal border of the denture and narrowed down to 2 mm in width through the hamular notch region. The scraping of the cast is done in such a fashion that the depth of the posterior palatal seal is maximum at the center and tapers to zero toward its anterior and posterior border.

59. Winland and Young surveyed the commonly employed posterior palatal seal designs and summarized them as follows : 1. A bead posterior palatal seal 2. A double bead posterior palatal seal 3. A butterfly posterior palatal seal 4. A butterfly posterior palatal seal with a bead on the posterior limit 5. A butterfly posterior palatal seal with the hamular notch area cut to half the depth of a no. 9 bur 6. A posterior palatal seal constructed in reference to House’s classification of palatal forms . On comparison of these designs with the scrapping techniques discussed above; a beaded PPS design results from Boucher’s technique of scrapping, a double-beaded technique

60. results from Bernard scrapping design for class III soft palate, butterfly PPS design using Swenson’s method , a butterfly design with a bead on the posterior limit results from Calomeni’s technique. A ) Silverman’s technique (B) Hardy and Kapur’s technique of PPS designs with the cross-sectional views depicted in wax

61. ADVANTAGES OF PLACING THE PALATAL SEAL ON THE TEMPORARY RECORD BASE The trial base will be more retentive which can produce a more accurate jaw relation The patient will get a psychologic security of knowing that retention will not be a problem with the final denture The dentist can assess the retentive qualities of the denture at an early stage

62. ADDING POSTERIOR PALATAL SEAL TO THE EXISTING DENTURE This technique is similar to fluid wax technique except that in this technique wax is added to an already existing denture. PROCEDURE After the wax has been placed in the PPS area, the denture is removed from the mouth. An indelible pencil is used to outline the anterior extent of the seal of the denture.

63. ADDING POSTERIOR PALATAL SEAL TO THE EXISTING DENTURE Utility wax is placed vertically across the palate separating the posterior two-thirds from the anterior region and extended across the posterior portion of the denture. Stone is vibrated into the denture wax surface outlined by the utility wax. After the stone has set, wax is eliminated and the denture is cleaned. The denture is then trimmed distal to the anterior vibrating line.

64. ADDING POSTERIOR PALATAL SEAL TO THE EXISTING DENTURE Lubricant is then applied to the unground areas including the polished surface of the denture and separating medium is applied to the cast Autopolymerising resin powder is then added into the area created by the elimination of the wax, and the cast is held firmly to the denture by rubber bands.

65. ADDING POSTERIOR PALATAL SEAL TO THE EXISTING DENTURE After the initial set has taken place,they are placed in a pressure pot with water (140⁰ F) for 20 minutes under 30 psi pressure. After the cast and denture are separated, the excess acrylic is trimmed off and the denture is polished.

66. UNDER EXTENSION The most common cause of failure of the seal in the posterior palatal area is the under extended distal denture border. Commonly, this is a result of the practitioner’s use of the fovea palatine as the landmark for terminating the denture base. By so doing, he may be depriving the patient of as much as 4 to 12 mm of tissue coverage.

67. UNDEREXTENSION The dentist may intentionally leave the posterior borders underextended in order to reduce the patient’s anxiety to gagging Underextended posterior borders frequently result when the Laboratory Technician is asked to trim and polish the processed denture borders.

68. UNDERPOSTDAMMING It may be the result of recording the tissue when the mouth was wide open during the final impression. The correction can easily be made by further scraping the cast and readapting the trial base if the conventional approach is used, or by adding more wax and reminding the patient to refrain from opening the mouth so wide if the fluid wax technique is employed .

69. OVERPOSTDAMMING It is not uncommon that the master cast was scraped too aggressively and the posterior palatal seal displaces too much tissue. Selective reduction of the denture border with a carbide bur, followed by lightly pumicing the area while maintaining its convexity will resolve the problem

70. CONCLUSION Although the posterior palatal seal has been discussed separately, it must be remembered that it is a part of overall peripheral seal. The main difference between this and rest of the peripheral seal is that it does not have tissues surrounding it and draping over it to provide a seal. Thus the manner in which seal is obtained in the posterior palatal region is different.

71. CONCLUSION The posterior palatal seal is obtained through intimate contact and the application of pressure within the physiologic limit by the denture in this region. This would require an intimate knowledge of the anatomy, functions and movements of the tissues of the region. 

72. REFERENCES: 1.Sheldon Winkler, Essential of complete denture prosthodontics, A.I.T.B.S. Publishers and Distributors,Ed:2 nd 2 . Lye TL. The significance of the fovea palatine in Complete Denture Prosthodontics. J Prosthet Dent 1975;33(5):504-10. 3 .Zarb G.A., Bolender C.L. Prosthodontic treatment for edentulous patients. Mosby, Ed:12 th . 4 . Heartwell C.M., Rahn A.O. Syllabus of complete dentures. Varghese Publishing house, Ed:5th. 5 Moghadam BK, Scandrett FR. A technique for adding the posterior palatal seal. J Prosthet Dent 1974;32(4):443-7. 6 . Kolb HR. Variable denture limiting structures of the edentulous mouth. J Prosthet Dent 1966;16(2):194-201. 7 . Chen MS. Reliability of the fovea palatine for determining the posterior border of the maxillary denture. J Prosthet Dent 1980; 43(2):133-37. Kim Y, Michalakis KX, Hirayama H.-Effect of relining method on dimensional accuracy of posterior palatal seal. An in vitro study-J Prosthodont . 2008 Apr;17(3):211-8. Epub 2007 Jan 11

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