Posterior Palatal Seal

This presentation describes in detail the significance of the posterior palatal seal and the various methods that have been proposed by various authors for locating and demarcating the PPS area.
This presentation also describes the various problems that may be encountered if the post dam is inadequate or in excess.

1. Posterior Palatal Seal Presented by: Swapnaneel P Guided by: Dr. Eswaran B

2. Contents Supporting and Limiting structures of maxilla Definition Functions Anatomic and Physiologic Considerations Parameters of PPS Techniques to record PPS Trouble shooting

3. Supporting Structures Mucous membrane Hard palate Residual ridge Maxillary tuberosity Rugae Prosthodontic Treatment for Edentulous Patients, Jarb Bolender ; pg. 212

4. Peripheral or Limiting Structures of Maxilla Labial Vestibule Labial frenum Buccal Vestibules Buccal frenum Vibrating Lines Hamular notch Prosthodontic Treatment for Edentulous Patients, Jarb Bolender ; pg. 214

5. Definition Posterior Palatal Seal area: “ The soft tissue area limited posteriorly by the distal demarcation of the movable and non-movable tissues of the soft palate and anteriorly by the junction of 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. ” – GPT 9 Posterior Palatal Seal: “ That portion of the intaglio surface of a maxillary removable complete denture, located at its posterior border, which places pressure, within physiologic limits, on the posterior palatal seal area of the soft palate; this seal ensures intimate contact of the denture base to the soft palate and improves retention of the denture. ” – GPT9

6. Functions of PPS Retention of Maxillary Denture Prevent food accumulation Increases patient comfort and reduces gag reflex Compensate for the volumetric shrinkage of methyl methacrylate resin that occurs during polymerization. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 146

7. Anatomic and Physiologic considerations

8. Soft palate Musculo-membranous curtain. Functions as flap valve closes off nasopharynx during swallowing. Part of a dual valve system which separates the oropharynx from the oral space and the nasopharynx from the nasal space.

9. Soft palate The function of the soft palate in these dual valving actions requires freedom of movement in three dimensions or planes of space, i.e., superior-inferiorly, mediolaterally and antero-posteriorly. An impression should be made patient is seated in upright position, with head flexed 30 degrees forward and placing the tongue under tension against either handle of impression tray or dentist’s fingers, and should not protrude beyond lips.

10. Muscles of soft palate Palatoglossus Origin – Palatine aponeurosis Insertion - Side of tongue Action - Draws palate down, raises tongue

11. Muscles of soft palate Palatopharyngeus : Origin – Arises as 2 fasciculi – Posterior fasciculi arises from palatine aponeurosis and anterior fascicule from posterior border of hard palate. Insertion – Lamina of thyroid cartilage, wall of pharynx and its median raphe. Action – Helps in pulling up the wall of pharynx and shortens it during swallowing.

12. Muscles of soft palate Tensor Veli Palatini - When taut, can influence the denture contour in the hamular notch area. Levator Palati - Closing of the oropharynx from the nasopharynx during swallowing and determining the position of the vibrating line. Palatopharyngeus – On contraction, draw the tongue and soft palate towards each other.

13. Pterygomaxillary notch/Hamular notch Band of loose connective tissue lying between the pterygoid hamulus of the sphenoid bone and the distal portion of the maxillary tuberosity. Lateral boundaries for the PPS. The pterygomaxillary notch is covered by pterygomandibular fold which extend from the posterior aspect of the tuberosity posteroinferiorly to insert into the retromolar pad. It influences the posterior border seal when the mouth is wide open during the final impression procedure. Hamular notch is covered by a thin mucous membrane. Thus should not be covered by denture.

14. Hamular process 2-4mm postero -medial to the distal limit of the maxillary residual ridge. Affects the length and direction of the pterygomaxillary seal. Covered by mucous membrane and should not be covered by denture.

15. Mid palatine raphe This overlies the medial palatal suture, contains little or no submucosa and will tolerate little compression. According to Heartwell and Rahn , this band of tissues is not meant to be compressed, rather should be relieved if prominent. When a prominent mid-palatine fissure is present in hard palate, it often extends to the soft palate. When this fissure is present it should be carefully reproduced in the master cast and posterior seal should be extended into this fissure for proper peripheral seal.

16. Fovea palatini Two glandular openings within the tissues of posterior portion of hard palate, usually lying on either side of midline. They are the ductal openings into which the ducts of other palatal mucosal glands drain. According to Lye, they are located, on average, 1.31mm anterior to anterior vibrating line. According to Chen, majority were located on or behind the anterior vibrating line. Thus, they do not represent the junction of hard and soft palate and should be used only as a guideline to placement of posterior palatal seal.

17. Vibrating Line “ An imaginary line across the posterior part of the soft palate marking the division between the movable and immovable tissues; this line can be identified when the movable tissues are functioning. ” – GPT 9 Anterior Vibrating line Posterior Vibrating line

18. Anterior Vibrating Line It is an imaginary line lying at the junction between the immovable tissues of the hard palate and the slightly movable tissue of the soft palate. Cupid bow’ shaped due to the projection of posterior nasal spine. Always on soft palate. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 149

19. Locating: Patient is asked to say “AH” with short vigorous bursts due to projection of the posterior nasal spine. “Valsalva” Maneuver

20. Posterior Vibrating Line An imaginary line at the junction of Tensor veli palatini muscles in the muscular portion of the soft palate. – Sheldon Winkler It represents the demarcation between the part of the soft palate that has limited or shallow movement during function and the remaining soft palate that shows marked displacement during functional movements. Marks the most distal extension of the denture base. Locating: patient is instructed to say “AH” in short vigorous burst in a normal unexaggerated fashion. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 150

21. Classification of Soft Palate Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 152 Classified as: Class I Class II Class III Based upon the angle the soft palate makes with the hard palate. The more acute the angle of the soft palate in relation to the hard palate, more muscular activity will be necessary to effect velopharyngeal closure (closing of the nasopharynx). So the more the soft palate is markedly displaced in function, the less that can be covered by the denture base. Determined when the patient is in upright position with the head held erect.

22. Class I Soft palate is rather horizontal when extended posteriorly with minimum muscular activity. Considerable separation (>5mm) between anterior and posterior vibrating lines. (Wide PPS) Most favorable configuration as more tissue surface can be covered and thus gives best Retention. Posterior Palatal seal – A Literature Review, International Journal of Prosthodontics and Restorative Dentistry; Bindhoo et. al

23. Class III Soft palate is acute in comparison to hard palate. <1 mm separation between anterior and posterior vibrating lines. Small PPS area and thus less retentive. Often found in conjugation with High V shaped palatal vault. Posterior Palatal seal – A Literature Review, International Journal of Prosthodontics and Restorative Dentistry; Bindhoo et. al

24. Class II Soft palate contour lies somewhat between Class I and Class III allowing 1 to 5mm of seal area depending on the muscular activity of the soft palate. Posterior Palatal seal – A Literature Review, International Journal of Prosthodontics and Restorative Dentistry; Bindhoo et. al

25. Palatal Throat Form (House classification) Class I : Large and normal in form with a relatively immovable band of resilient tissue 5-12 mm distal to a line drawn across distal edge of the tuberosities. Class II : Medium size and normal in form with relatively immovable resilient band of tissue 3-5 mm distal to a line drawn across distal edge of the tuberosities. Class III :- Usually accompanies a small maxilla. The curtain of soft tissues turns down abruptly 3-5 mm anterior to a line drawn across distal edge of the tuberosities.

26. Pterygomaxillary seal Extends through pterygomaxillary notch continuing 3-4 mm anterolaterally approximating the mucogingival junction. Occupies the entire width of hamular notch. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 147

27. Parameters of PPS

28. Size According to Hardy and Kapur (1958) , the dimension of PPS was 2 mm at the mid-palatal region and hamular notch and 4mm at the greatest curvature region of PPS. Silverman performed a study on 92 patients & found the following – The greatest mean anteroposterior width of PPS is 8.0 mm (with 5-12 mm of range) The mean width was found to be different for right (8.2mm) and left side (8. 1mm). The interhamular notch distance was found to be 35.8 mm (25-48mm range) The interhamular notch distance was found to be different for males (37.1 mm) and females (35.6 mm) Winland and Young, maxillary complete denture posterior palatal seal: variation in shape size and location, j prosthet dent , march,1973

29. Shape • BEAD • DOUBLE BEAD • BUTTERFLY • BUTTERFLY WITH BEAD Winland and Young, maxillary complete denture posterior palatal seal: variation in shape size and location, j prosthet dent , march,1973

30. Classification of Techniques to record PPS Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University Hardy and Kapur (1958) – Functional : Final impression is border molded in PPS area with soft stick modeling compound / wax by sucking movements performed by the patient. Semi functional : Border molding is done by the dentist. Empirical : Developed on the cast by grooving the cast to the desired depth. Hardy and Kapur , posterior palatal seal- its rationale and importance, j prosthet dent may 1958

31. Techniques to locate and record PPS Conventional technique Fluid wax technique Arbitrary scraping of the master cast Extended palate technique Adding PPS to an existing denture Determination of PPS by ultrasound

32. Conventional technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154 Final impression is made, boxed, and poured. A well-adapted resin/shellac tray is fabricated on the stone cast. The posterior palatal area is then dried with gauge; a “T” burnisher /a mouth mirror is used to palpate for the hamular process and marked with an indelible pencil

33. Conventional technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154 The instrument (“T” burnisher/mouth mirror) is then placed along the posterior angle of the tuberosity until it drops into the pterygomaxillary notch. A line is placed with an indelible pencil, through the notch and extended 3-4mm anterolateral to the tuberosity, approximating the mucogingival junction. The same procedure is then performed on the opposite side. This will complete the outlining of the pterygomaxillary seal.

34. Conventional technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154 The resin /shellac tray is then inserted into the mouth and the indelible pencil lines are transferred to the tray, which is returned to the master cast to complete the transfer of posterior border and tray is trimmed. The palatal tissues anterior to the posterior border are palpated with the “T” burnisher /mouth mirror to determine their compressibility in width and depth.

35. Conventional technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154 The use of Valsalva maneuver / visualizing the area when the patient says “ah” with short vigorous bursts may also be used. This line is marked with the indelible pencil and transferred to the master cast. A Kingsley scraper is used to scrape the cast.

36. Conventional technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154 The deepest area of the seal are located on the either side of the midline, one third the distance anteriorly from the post vibrating line. It is scraped to the depth of the approximately 1-1.5mm. The tissue covering the median palatal raphe has little submucosa and cannot withstand the same compressive force on the tissues lateral to it. It is scraped to the depth of approximately 0.5-1.0mm.

37. Conventional technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154 Just posterior to the deepest portion of the seal, it is also tapered to the posterior vibrating line. Failure to taper the seal posteriorly may lead to tissue irritation. Shellac can be readapted to conform to the scored palatal seal area and tried in the mouth to evaluate the retentive qualities of the trial base.

38. Advantages Trial base is more retentive Psychologic security to the patient Practitioner can determine the retentive qualities in the finished denture Patient realizes the posterior extent which may ease the adjustment period Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154

39. Disadvantages Not a physiologic technique. Potential for over compression of tissues. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 154

40. Fluid wax technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 155 Similar to the conventional technique except that in this technique the indelible transfer markings are recorded on the final wash impression. All the procedures for location and transfer marking of the anterior and posterior vibrating lines are same as for the conventional approach. Indelible transfer markings are recorded on the final wash impression.

41. Fluid wax technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 155 Zinc oxide and eugenol /plaster are preferred over the elastic impression material, as they set rigid. 4 types of wax : Iowa Wax (White) – Dr. Earl S. Smith Korecta Wax no.4 (Orange) – Dr. O.C. Applegate H-L physiologic paste (Yellow-White) – Dr. C.S. Howkins Adaptol (Green) – Dr. Nathan G. Kyne

42. Fluid wax technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 155 Designed to flow at mouth temperature. The melted wax is painted onto the impression surface with the outline of the seal area and allowed to cool to below mouth temperature to increase its consistency and make it more resistant to flow. The impression is carried to the mouth and held in the place under gentle pressure for 4-6 minutes to allow time for the material to flow.

43. Fluid wax technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 155 After 4-6 minutes, the impression tray is removed from the mouth and the wax examined for uniform contact through out the posterior palatal seal area. If tissue contact has not been established, the wax will appear dull. If the tissue has been contacted, the wax will have a glossy appearance. Where the wax appears dull, more wax should be applied and the procedure repeated.

44. Fluid wax technique Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 155 The secondary impression is reinserted and held for 3-5 minutes of firm pressure applied to the mid-palatal area of the impression tray.

45. Precautions The patient should not protrude his tongue beyond the approximated position of the incisal edge as this may shorten the posterior border of the final impression. The patient should be cautioned against rinsing with cold water as this may contract the tissues and reduce the flow properties of wax. The borders of the wax should terminate in feather edge towards the vibrating line. If a butt joint is formed, proper flow may have not taken place.

46. Advantages Physiologic technique Over compression of tissues is avoided Posterior palatal seal is incorporated into the trial denture base for added retention Mechanical scraping of the cast is avoided

47. Disadvantages More time is necessary during the impression appointment Difficulty in handling materials

48. Extended Palatal technique (Silverman 1971) Denture border is extended 8mm approximately beyond the anterior vibrating line. Not widely used currently. Method - After border molding tray is extended by adding compound. Green stick compound is added to the seal area and record is made with head flexed 30 degree downward.

49. Arbitrary Scraping of the Cast Anterior and the posterior vibrating lines are visualized by examining the patient’ mouth and approximately marked on the master cast. Least accurate and leaves a chance at insertion appointment since it relies on dentist’s recollection of palatal configuration and tissue compressibility. Inaccurate and not physiological.

50. Boucher’s technique Stage of recording- during jaw relations Method the posterior vibrating line is located and transferred on to the master cast. The temporary denture base is reduced to this line. This will create a raised narrow and sharp bead along the posterior portion of the denture which sinks into the tissues and forms a seal. Advantage: According to Boucher a narrow bead like seal is more effective. Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University

51. Bernard Levin’s Technique For class III soft palate forms: He described a, “double bead” technique for class III soft palate. In this technique, a depth of about 1mm and width of 1.5mm is scraped in posterior vibrating line. A distance 3 to 4 mm from posterior border, anterior vibrating line is beaded. This is known as rescue bead. Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University

52. Bernard Levin’s Technique For class I and class II soft palate. Using no. 8 round bur of 2mm diameter, 2 holes of 2mm are drilled at the depth of the bur in the area between the midline and hamular notch. One hole of 1mm depth is drilled to half the diameter of the bur in the center. A cone shaped acrylic resin bur is used to rough out the seal. The hamular notch region is not reduced more than 0.25mm in width and 0.5mm in depth and not extended onto the tuberosity and vestibule. The soft tissue part of the seal is scraped to 6mm in width where , the median raphe region is scraped to 4mm in width. Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University

53. 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. Posterior line is tapered towards the anterior line by scraping the cast. Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University

54. Calomeni , Feldman, Kuebker’s Technique In this technique a depth of 1 to 1.5 mm scraped as posterior bead in which extends through hamular notches and distance of 5 to 6 mm from posterior line, anterior line is beaded. Using a Kingsley scraper No.1 a depth 0 at anterior line to a depth of 1 to 1.5 mm along posterior border is scrapped. A distance of 2 to 3 mm should be present in between the anterior and posterior lines from the midline. Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University

55. Pound’s Technique Pound recommends a single bead posterior palatal seal with anterior extensions for additional air seal. In the palate from the hamular notch to hamular notch a ‘V’ shaped groove is carved measuring a width of 1 to 1.5 mm and depth of 1 to 1.5 mm and is placed 2 mm anterior to vibrating line. In order to provide adequate air seal a loop is carved on either side of the midline. Palpate the area with a blunt of the instrument to determine the width of anterior loop. Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University

56. Hardy and Kapur Technique Using the ball portion of the T burnisher depth of posterior palatal seal is examined. The posterior palatal seal is extended 4 mm from distal border of denture . Then the hamular notch region is narrowed to 2 mm in width through the hamular notch. Posterior palatal seal is at its maximum depth in center and minimizes to zero at its anterior and posterior border by scraping the cast. Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University

57. Adding PPS to existing denture Mark the vibrating line in the mouth with an indelible marker. Form the desired thickness and extension of the PPS on the denture in the patient’s mouth with softened green modeling compound. Transfer the locations of the vibrating line to the denture. Make a cast of the intaglio surface of the denture; the cast must include all of PPS addition and extend 5 to 6 mm posteriorly Use a scalpel to cut channels which will allow excess auto polymerizing acrylic resin to escape. Remove the green stick compound and replace with auto polymerizing resin in a pressure pot.

58. Correction of posterior palatal seal by using a visible light cured resin (Arthur Nimmo) Identify and mark the vibrating line in the mouth with an indelible marking stick. Roughen the denture surface in the posterior palatal seal area with a carbide bur. Adapt the VLC resin. Place the denture in the mouth and allow it to remain in place for approximately 3 minutes. During this time the material will flow. Position a hand-held visible light source near the border of the denture and apply light directly to the region for several minutes. Remove any excess resin with a carbide bur and smooth the junction between the seal and the polished surface of the denture.

59. Advantages of using VLC resin No exothermic reaction to irritate the oral tissues. Minimal volumetric shrinkage during curing. More closely approximates a physiologic technique. Can be performed with relatively little chair time.

60. Determination of PPS by Ultrasound Rajeev M. Narvekar , and Marc B. Appelbaum investigated the anatomic position of posterior palatal seal by ultrasound. Ultrasound refers to sound with frequencies higher than the audible range (20 to 20,000 Hz). Basic elements of an ultrasound scanning system include – Transducer Couplant

61. Trouble shooting Under extension Under postdamming Over postdamming Over extension Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 162

62. Under extention Most common cause for failure of the seal in the posterior palatal area Causes: Practitioner’s use of the fovea palatine as the landmark for terminating the denture base. By doing, so he may be depriving the patient of as much as 4 to 12 mm of tissue coverage. Failure of the dentist to carefully examine the hard and soft palates, making note of the palatal configuration. Over trimming of posterior border by laboratory technician Due to fear of gagging Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 162

63. Under Postdamming May be the result of recording the tissue when the mouth was wide open during the final impression. When the mouth is in the wide open position, the pterygomandibular fold becomes taut. When the patient assumes any position other than a wide open position, a space will be present between the denture base and the tissue since the fold is no longer activated. Diagnosis : place the wet denture base into the mouth and slowly press in the mid-palatal region until it is firmly seated while observing the distal denture border. If air bubbles are seen escaping from beneath the distal border, then at that point the denture base is under postdammed . Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 162

64. Correction Further scrap the cast and readapting the trial base if the conventional approach is used Add more wax and remind the patient to refrain from opening the mouth so wide if the fluid wax technique employed. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 162

65. Over Postdamming Over scrapping of master cast and the posterior palatal seal displaces too much tissue. Significant over post damming especially in the pterygomaxillary seal area - posterior border will be displaced inferiorly. Moderately over post dammed - tissue irritation across the posterior palatal region. Correction: Selective reduction of the denture border with carbide bur, followed by lightly pumicing the area while maintaining its convexity. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 162

66. Over extension The most frequent complaint from the patient will be that swallowing is painful and difficult. Small ulcerated areas in the region of the soft palate will be evident. If the hamuli are covered by the denture base, the patient will experience sharp pain, especially during function. Correction: By marking the lesion with an indelible pencil and transferring it to the denture base, the precise position of the overextension can be removed with a bur and then carefully repolished. Essentials of Complete Denture Prosthodontics, Sheldon Winker; Pg. no. 162

67. Referances Essentials of Complete Denture Prosthodontics, Sheldon Winker Prosthodontic Treatment for Edentulous Patients, Jarb Bolender Techniques to record posterior palatal seal; Agrawal, et al .; 2021; Journal of Datta Meghe Institute of Medical Sciences University Posterior Palatal seal – A Literature Review, International Journal of Prosthodontics and Restorative Dentistry; Bindhoo et. al Hardy and Kapur , posterior palatal seal- its rationale and importance, j prosthet dent may 1958 Winland and Young, maxillary complete denture posterior palatal seal: variation in shape size and location, j prosthet dent, march,1973

68. Thank you