|Year : 2020 | Volume
| Issue : 4 | Page : 702-708
Techniques to record posterior palatal seal: A review
Shanvi Agrawal, Seema Sathe, Dipak Shinde, Tanvi Balwani
Department of Prosthodontics and Crown and Bridge, Sharad Pawar Dental College and Hospital, Datta Meghe Institute of Medical Sciences (Deemed to be University), Sawangi (Meghe), Wardha, Maharashtra, India
|Date of Submission||19-Jun-2020|
|Date of Decision||09-Oct-2020|
|Date of Acceptance||20-Oct-2020|
|Date of Web Publication||11-May-2021|
Dr. Shanvi Agrawal
Department of Prosthodontics and Crown and Bridge, Sharad Pawar Dental College and Hospital, Datta Meghe Medical Sciences, Sawangi (Meghe), Wardha, Maharastra
Source of Support: None, Conflict of Interest: None
A denture which is fabricated having adequate retention helps in patient's esthetic, physiological, and functional factors. The diagnostic assessment of the posterior palatal seal (PPS) and its placement is of pronounced significance. With an accurate recording of PPS area, we can establish the border seal in the posterior region of the maxillary denture. There are a number of dentures which have become unsuccessful due to the inadequate establishment of the posterior limit and an improper PPS. This article review focuses on the importance of the PPS and about different techniques associated with recording of it.
Keywords: Border seal, hamular notch, posterior palatal seal, soft palate, vibrating line
|How to cite this article:|
Agrawal S, Sathe S, Shinde D, Balwani T. Techniques to record posterior palatal seal: A review. J Datta Meghe Inst Med Sci Univ 2020;15:702-8
| Introduction|| |
The diagnostic assessment of the posterior palatal seal (PPS) and its placement is of pronounced significance.
The distal limit of the upper denture has definitive boundaries which make the location of PPS an easy and rapid technique with predictable outcome.
The PPS is defined as “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 PPS area of the soft palate; this seal ensures intimate contact of the denture base to the soft palate and improves retention of the denture”-GPT-9.
PPS is divided into two distinct but confluent areas: postpalatal seal, which ranges medially from one tuberosity to the other and pterygomaxillary seal, which ranges through hamular notch and continuing for 3–4 mm anterolaterally approaching the mucogingival junction [Figure 1]. PPS area lies between the anterior and posterior vibrating lines.,
|Figure 1: Posterior palatal seal – postpalatal seal and pterygomaxillary seal|
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| Rationale for Posterior Palatal Seal|| |
To create a partial vacuum beneath the upper denture, which gets activated simply when horizontal or lateral tipping forces are directed toward the denture base.
| Functions of Posterior Palatal Seal|| |
- It helps in complete denture retention
- It acts as a barrier and reduces the accumulation of air, fluid, and foodstuff in the middle of the denture and tissue surface
- By establishing a positive interaction with the functioning soft palate, it aids in decreasing the gag reflex
- It serves as a guide for the placement of custom tray while impression making
- It compensates for the warpage occurring during polymerization by providing a thick border
- By enhancing the retention of a denture, it offers comfort and confidence to the patient.
| Parameters of Posterior Palatal Seal|| |
It is variable in its shape, size, location, tissue displaceability, and anatomical configuration and relationship of soft and hard palate.
| Classification of Soft Palate|| |
Class 1: Relatively immovable resilient band of tissue 5–12 mm distal to a line drawn through the distal edge of the tuberosities, large and normal in form [Figure 2].
|Figure 2: Class 1 soft palate (a) hard palate, (b) soft palate, (c) palatal extension of denture|
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Class 2: Relatively immovable resilient band of tissue 3–5 mm distal to a line drawn through the distal edge of the tuberosities, medium size and normal in form [Figure 3].
|Figure 3: Class 2 soft palate (a) hard palate, (b) soft palate, (c) palatal extension of denture|
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Class 3: The drape of soft tissues goes down abruptly 3–5 mm anterior to a line drawn through the palate at the distal edge of the tuberosities, generally accompanies a small maxilla [Figure 4].
|Figure 4: Class 3 soft palate (a) hard palate, (b) soft palate, (c) palatal extension of denture|
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Hardy and Kapoor – the dimension of PPS was 4 mm at the greatest curvature region of PPS and 2 mm at the hamular notch and midpalatal area. Silverman – maximum average anteroposterior width of PPS is 8.0 mm (having a range of 5–12 mm).
Winland and Young found that five different forms of PPS were commonly used.
- Single bead at the distal margin of the denture
- Double bead, one at the distal margin and other one anterior to it
- Butterfly-shaped PPS
- Butterfly-shaped PPS having a bead at a distal end
- Butterfly shaped having widened PPS having notching in area of hamular notch.
Location shows much variance, but averagely anterior vibrating line is 1.31 mm distal to fovea palatini.
Low compressibility has been observed in the region of midpalatal raphe and hamular notch and high compressibility in the lateral portion of cupids bow. Its variance based on the form of palatal vault like it is deep in Class III palate, while in Class I palate PPS area, it remains shallow.
| Techniques for Recording of Posterior Palatal Seal|| |
Hardy and Kapur,
- Functional technique
- Semi-functional technique
- Empirical technique.
Fluid wax technique
This technique is used after taking a wash impression. Low melting, i.e., Iowa wax (white), H-L physiologic paste (yellow–white), Korecta wax no. 4 (orange), and Adaptol (green) are used in this technique.
At first, marking of anterior and posterior vibrating line is done inside the patient's oral cavity with the aid of an indelible pencil, which is then transferred to the wash impression.
Fluid wax is coated in an additional amount in the boundaries of the palatal seal [Figure 5], and head of the patient is positioned 30° inferior to F-H plane. With this, the soft palate is positioned at its most downward and forward position, and aspiration of impression material and saliva is avoided [Figure 6]. Position the patient's tongue against lower anteriors as it aids in the anterior pulling of the palatoglossus.
|Figure 5: Fluid wax is coated on the boundaries of the posterior palatal seal|
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|Figure 6: Patient's head is positioned 30° inferior to Frankfort's horizontal plane|
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Place the custom tray inside the patient's mouth and ask him to rotate the head periodically to achieve soft palate functional movements without varying the plane. Afterward, the tray is removed in 4–6 min. Regions having tissue approximation appear glossy and other remains dull, in which wax is added again and repeat the process.
By performing the border molding, the denture borders are molded to their functional contours using low-fusing modeling compound. For an accurate border seal, the PPS must be added. Greenstick compound softened over flame and traced over the posterior border of tray from the buccal to the hamular notch area across the midline to the similar area on the opposite side and flamed to merge the addition into the original tray material, tempered, and then inserted into the mouth. After removal, the excess is trimmed back to the original length.
It is established on the cast by scraping the cast to the preferred depth.
Conventional technique (Winkler)
Stage of recording – once an accurate and completely extended final impression has been made.
- Patient has been seated in the upright position
- Patient is requested to rinse with astringent mouthwash
- Palatal tissues are made damp-dry
- Hamular notches located with T-burnisher and marked with indelible pencil
- Posterior vibrating line located by requesting the patient to say “ah” in an unexaggerated fashion [Figure 7]
- Tray is then placed inside the mouth, and markings are transferred onto the master cast by placing the tray onto the cast
- Anterior vibrating line marked by requesting the patient to say “Ah” in a short vigorous burst
- Again, markings are shifted to the cast from the tray which is held firmly to place, in the patient's mouth
- Kingsley scraper is used to score the cast. The deepest regions of the seal are positioned on both sides of the midline, at a distance of one-third anteriorly from the posterior vibrating line. It is generally scraped 1–1.5 mm deep [Figure 8].
Baseplate is readapted to the conform scored cast.
A bead of 1.5 mm depth and 1.5 mm width at its base should have a sharp apex on the denture ensuing in a design of a beaded PPS [Figure 9].,
Bernard Levin's technique
A “double bead” design should be preferred in the situation with Class III soft palate forms. A width of 1.5 mm and depth of about 1 mm are scored in posterior vibrating line. A rescue bead is also given at a distance of 3–4 mm extending from the posterior border, and the anterior vibrating line is beaded.,
A bead of 1–1.5 mm deep is cut along the distal border that will cause it to stand straight out from the hard palate, turning neither up nor down. The cast is scraped so that the posterior line is tapered toward the anterior line.
Calomeni, Kuebker, Feldman's technique
A 1–1.5 mm deep groove is scraped using Kingsley scraper No. 1 as a posterior bead extending across hamular notches, and anterior line is beaded at 5–6 mm distance from the distal line. Extending from the midline between anterior and posterior vibrating lines, the distance should be 2–3 mm.,
A single bead PPS having anterior extensions for additional air seal. In a shape of “V,” a bead having a dimension of 1.5 mm width and depth is scraped in the palate between the hamular notches which is located 2 mm anterior to the vibrating line. For adequate air seal, the loop is scored on both sides of the midline.
In the middle of anterior and posterior flexion lines, a line is drawn across hamulur notches using an indelible pencil. A flexion line is marked anteriorly with a narrow groove, and posteriorly, a line is grooved to the half depth of that of midscore line. From the midline to the anterior and posterior vibrating line, depth of the cast is tapered.
Hardy and Kapur technique
The depth of PPS is measured using the ball side of the T-burnisher. The PPS is placed 4 mm from posterior limits and tapered to 2 mm in the hamular notch region having its maximum depth in center and by scraping the cast, which minimizes to zero at its anterior and posterior border.
| Technique to Record Posterior Palatal Seal using Ultrasonic Method|| |
Rajeev and Applelboum utilized ultrasonic effects of nonionizing energy to displace electrons from the orbital shell.
Indication – Class I and II type of palates (as Type III palate patients avert whole adaptation of transducer). Contraindication – in patients with neuromuscular impairments and pronounced gag reflex.
Miniature transducer (10 MHz linear array) is used along with a real-time B-mode to view image of soft tissue [Figure 10].
- Mark PPS using conventional method
- A thin rubber band is placed on the anterior one-third of transducer, which serves as an index that would appear in monitor
- Toothpaste is used as a line couplant
- Transducer is taken intro oral cavity [Figure 11]
- Initially moved posteriorly to the left of midline to locate hard and soft palate junction
- on the posterior vibrating line, the rubber band is seen, there was no display, and a Polaroid picture was made
- Then, it was displaced to the right side of palate
- The average distance of posterior vibrating from junction of hard and soft palate is 2–9 mm with 4–6 mm wide PPS.
| Recent Techniques for Recording Posterior Palatal Seal|| |
Using a nonfluid wax addition technique
- PPS area delineated by indelible pencil [Figure 12]
- Transferred to definitive impression [Figure 13]
- PPS area abraded by aluminum oxide [Figure 14]
- Zone of microabrasion [Figure 15]
- Mixture of half baseplate wax – half sticky wax is melted and coated onto the impression [Figure 16]
- Definite cast with defined PPS [Figure 17].
|Figure 16: Mixture of half baseplate wax – half sticky wax melted and coated to impression|
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Transferring posterior palatal seal from tissue surface to working cast
- Marking of the anterior vibrating line [Figure 18]a
- Marking of the posterior vibrating line [Figure 18]b
- Covering the area between two lines [Figure 18]c
- Transfer of line onto baseplate and trimmed accordingly [Figure 19]a
- Placed inside the mouth and rechecked [Figure 19]b
- Placed onto the cast and markings are transferred [Figure 19]c.
|Figure 18: (a) Marking of anterior vibrating line, (b) marking of posterior vibrating line, (c) covering the area between two lines|
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|Figure 19: (a) Transfer of line onto baseplate and trimmed accordingly, (b) placed inside mouth and rechecked, (c) placed onto the cast and markings are transferred|
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Using thermoplastic sheet
- A – Mark the anterior and posterior vibrating line with an indelible pencil intraorally [Figure 20]a
- B – On the thermoplastic sheet, the anterior and posterior vibrating lines are transferred [Figure 20]b
- C – Posterior vibrating line is used as a reference to trim the thermoplastic sheet [Figure 20]c
- A – Onto the definitive cast, posterior vibrating line is transferred [Figure 21]a
- B – Up to the anterior vibrating line, the sheet is trimmed [Figure 21]b
- C – After which on the definitive cast, the ant vibrating line is transferred [Figure 21]c
- Troubleshooting [Table 1].
|Figure 20: (a) Marking of anterior and posterior vibrating line using an indelible pencil. (b) Transfer of markings to thermoplastic sheet. (c) Thermoplastic sheet trimmed to posterior vibrating line|
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|Figure 21: (a) Transfer of posterior vibrating line to definitive cast. (b) Thermoplastic sheet trimmed to the anterior vibrating line. (c) Transfer of anterior vibrating line to definitive cast|
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| Conclusion|| |
Locating the PPS area is definitely not a challenging process provided with anatomy and physiology is thoroughly understood. A proper inspection is required throughout while diagnosis and treatment planning. It is very important to recognize the techniques which should be used for the border seal for the retentive prosthesis. All of this is done to ensure that the patient is satisfied, which is practitioner's main concern.,,,,,,
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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