Classification Of Soft Palate Short Notes

Question. Classification of the soft palate.
Answer:

House’s classification of the soft palate

It depends on the amount of posterior tissue that will accept the posterior palatal seal:

• Class 1: More than 5 mm of movable tissue available for post-damming, ideal for retention.
• Class 2: 1–5 mm of movable tissue available for post-damming, good retention is usually possible.
• Class 3: Less than 1 mm movable tissue available for post damming, retention is usually poor.

House’s classification of palatal throat forms

• Class 1: Large and normal in form, relatively with an immovable band of tissue 5 to 12 mm distal to a line drawn across the distal edge of the tuberosities.
• Class 2: Medium-sized and normal in form, with a relatively immovable resilient band of tissues 3 to 5 mm distal to a line drawn across the distal edge of the tuberosities.
• Class 3: Usually accompanies a small maxilla. The curtain of soft tissue turns down abruptly 3 to 5 mm anterior to a line drawn across the palate at the distal edge of the tuberosities.

Soft Palate and Palatal Throat Form

The relationship between the soft palate and the hard palate is called the palatal throat form. On this basis, soft palates can be classified as:

• Class 1: It is horizontal and demonstrates little muscular movements. In this case, more tissue coverage is possible for the posterior palatal seal.
• Class 2: soft palate makes a 45-degree angle to the hard palate. Tissue coverage for the posterior palatal seal is less than that of a class I condition.
• Class 3: Soft palate makes a 70-degree angle to the hard palate. Tissue coverage for the posterior palatal seal is minimum.

Question. Masseteric notch.
Answer:

Masseteric notch area: It is immediately lateral to the retromolar pad and continuous anteriorly to the buccal vestibular sulcus.

Masseteric notch Significance

• When the masseter is activated, it pushes the buccinator medially against the denture borders in the area of the retromolar pad.
• Due to the contraction of the masseter, a depression is formed at the distobuccal corner of the retromolar pad.
• This is a dislodging force, and the denture border should be contoured to accommodate this interaction between the buccinator and masseter muscles. This counter in the denture base is termed a masseteric groove.

Masseteric notch Clinical Consideration.

1. During wide mouth opening the denture borders can cut into the tissue if the denture base is not properly shaped in that area.
2. During the impression procedure in the area of the masseteric notch downward pressure is applied and the patient is asked to close the mouth against the pressure.
3. Overextension of the denture causes laceration.

Question. Modiolus
Answer:

The modiolus is a strong knot of muscle that alters the position of the angle of the mouth.

Modiolus The main muscles that converge at the modiolus are:

• Buccinator
• Orbicularis oris
• Zygomaticus major
• Levator anguli oris and
• Depressor anguli oris.

Free movement of this knot of muscle must be ensured if the lower denture is to be stable. The modiolus determines the position of the premolar teeth and the shape of the polished surface in that region. This produces a narrowing of the denture so that the polished surface does not hinder the movements of the modiolus during function.

Question. Retromolar Pad
Answer:

Retromolar Pad Location: The retromolar pad is a triangular soft pad of tissue at the posterior end of the alveolar arch just at the inferior medial attachment of the mediotemporal tendon at the distal end of the lower ridge. The distal end of the mandibular denture region is bounded by the anterior border of the ramus.

Retromolar Pad Contents

1. Glandular tissue.
2. Fibers of the temporalis tendon.
3. Buccinator fibers enter it from the buccal side.
4. Fibers of the superior pharyngeal constrictor enter it from the lingual.
5. The pterygomandibular raphe enters the pad at its super posterior inside corner.

Retromolar Pad Significance of retromolar pad

1. The actions of contents within the retromolar pad limit the extent of the denture.
2. The contents within also prevent the placement of extra pressure on the retromolar pad during impression procedures or when reducing the posterior borders of the pad on the cast.
3. The retromolar pad must be covered by the denture to perfect the border seal in this region.
4. The retromolar pad posteriorly defines the posterior limit of the denture.
5. The height of the pad can be used as a guide in determining the plane of occlusion for dentures. The occlusal plane should lie at the junction of the upper and middle thirds of the retromolar pad.
6. It aids in the stability of the denture by adding another plane to resist the movement of the base. The retromolar region is fairly constant, as alveolar resorption is less in this region hence, the distal end of the denture should cover as much of the pad as possible.

Retromolar Pad Adjusting Special Tray

The retromolar pad is encapsulated by the tray, without being pushed buccally or lingually. Trimming the inner surface of the tray can provide relief in this area.

Retromolar Pad Border Molding

• The tray is placed in the mouth, after the area directly over the pad is softened with a Hanau torch, resculptured with the broad rounded end of a wax spatula, tempered, and checked again in the mouth until the desired relief is attained.
• The retromolar pad area is completed by the addition of tracing stick compound to the border, which is well tempered, the tray stabilized and the patient is instructed to open wide several times which will clear any raphe interference at the distal aspect of the denture.
• The occlusal surfaces of the natural molar teeth are slightly above the height of the retro-molar
  pad. The distal extension on the retromolar pad is limited by the anterior border of the ramus, the temporal tendon, the buccinator muscle, and the pterygomandibular raphe.

Question. Tongue and lateral throat form.
Answer:

Tongue

• The tongue is a powerful group of muscles and it is in constant contact with the denture at rest and during function. During rest, the two critical areas for the tongue are the anterior lingual flange and posterior to the molar teeth.
• The polished surfaces must be correctly shaped to allow for the tongue to lie unhindered in these areas. During the function, the position of the anterior and posterior teeth is critical.
• If the anterior or posterior teeth are set lingually the tongue will be cramped and the denture will be displaced during function. There must be sufficient tongue space to allow for movement.
• The occlusal plane is also important for stability. It should not be too high as to ‘wall in’ the tongue but should allow it to lie on the occlusal surface during rest.

Classification Of Tongue

Position of the Tongue—Wright Classification

Tongue Class 1 (favorable): Tongue lies on the floor of the mouth with the tip forward and slightly below the lower incisal edges

Tongue Class 2 (unfavorable): The tongue is flattened and broadened but the tip is in a normal position.

Class 3 (unfavorable): Tongue is retracted and depressed into the floor of the mouth, providing no border seal.

Tongue Sizes—House Classification

Tongue Class 1: Normal in size, development, and function. Sufficient teeth are present to maintain this normal form and function.

Tongue Class 2: Teeth have been absent long enough to permit a change in the form and function of
the tongue.

Tongue Class 3: Excessively large tongue. All teeth are absent for an extended period of time, allowing for abnormal development of the size of the tongue. Insufficient dentures can sometimes lead to the development of a Class 3 tongue.

Tongue Size Of The Tongue

Tongue Macroglossia: Prolonged edentulous state leads to an enlarged tongue. This will lead to difficulty in impression-making and denture instability.

Tongue Macroglossia: A small tongue could jeopardize the lingual seal.

Tongue Ankyloglossia: An ankylosed tongue has restricted movements and poses a problem in impression-making and denture retention. Normal attachment of the frenum is 8.03 mm below the gingival sulcus. In tongue-tie, it is 3 or 4 mm.

Tongue Management

A groove can be made in the lower denture to program the tongue by asking the patient to
consciously position the tongue over the groove in case of macroglossia.

Tongue movements during functional impression:

• During mandibular edentulous impression-making, the tongue is protruded and pressed against the anterior palate to activate the mylohyoid muscle, which determines the length and slope of the lingual flange.
• During maxillary edentulous impression, the tip of the tongue should touch the handle of the tray. This pulls the palatoglossus anterior and molds the posterior border of the impression and prevents the flow of the material into the throat.

Tongue Space

• If it is too lingual can lead to reduced tongue space and cause altered speech and dislodgement of the denture.
• If the vertical dimension is too less, space for the tongue will reduce and the tongue falls back leading to a gagging reflex.

Adaptability of Tongue

• The tongue responds to the loss of posterior teeth and alveolar bones by changing its size to bring the lateral borders in contact with the buccal mucosa.
• When a denture is introduced, the intrinsic musculature conforms to the shape of the tongue in the space available. Retraining of tongue activity also occurs.

Tongue Retention of Denture

• The tongue fits the lingual surfaces of the lingual flanges and provides the border seal on the
  lingual side.
• The base of the tongue is guided on top of the lingual flange. This provides the border seal at the back of the mandibular denture.

Tongue Speech

• Due to the extreme adaptability of the tongue most patients master speech within weeks of using the new denture.
• However, if the denture is not technically sculpted, speech defects can occur especially with ‘s’ sounds. A rugae pattern in the denture can aid the tongue in the production of ‘s’ and ‘ch’ sounds.

Tongue Lateral Throat Form

Tongue Neil Classification

• Class 1- deep lateral throat form
• Class 2- moderate lateral throat form
• Class 3- shallow lateral throat form.

Tongue Boundaries

• Anteriorly
• Posterolaterally
• Posteromedially
• Medially
• Laterally
• Mylohyoid muscle
• Superior constrictor
• Palatoglossus
• Tongue
• Pear-shaped pad

Located posterior to the mylohyoid ridge and bounded posteriorly by the fibers of the superior constrictor of the pharynx.

Tongue Significance

The distolingual portion of the flange is influenced by the glossopalatine and superior constrictor muscles, which on stretching constitute the retro mylohyoid curtain.

Constitutes the most important bracing potential in the mandibular foundation.

Tongue Clinical Consideration

This area has to be recorded very critically for the stability of the mandibular dentures.

Question 66. Alveololingual sulcus.
Answer:

Alveololingual Sulcus

It is the space between the residual ridge and the tongue. It can be divided into 3 regions:

• Anterior reg
• Middle region
• Posterior region.

Alveololingual sulcus Anterior Region

• It extends from the lingual frenum to where the mylohyoid curves down below the level of the sulcus.
• Here a depression can be palpated – “premylohyoid fossa”.
• It is also affected by the action of the genioglossus muscle.

Alveololingual sulcus Middle Region

• It extends from the mylohyoid fossa to the distal end of the mylohyoid ridge, covering medially from the body of the mandible.
• The middle of the lingual flange is made to slope towards the tongue so that it extends over the mylohyoid muscle and also the functional movement of the muscle.

Alveololingual sulcus Posterior Region

It is called retro mylohyoid space or lateral throat form. It starts from the mylohyoid ridge to the retro mylohyoid curtain, bounded by the anterior tonsillar pillar (palatoglossus) fold, superior constrictor muscle of the pharynx, and retromolar pad.

Alveololingual sulcus Theories Of Impression Making

• Pressure theory/ much compressive theory
• Minimal pressure theory/ mucositis theory
• Selective pressure theory.

Alveololingual sulcus Pressure Theory/Mucocompressive Theory

• Proposes that tissues recorded under functional pressure (mastication) provided better support and retention for the denture.
• The peripheries of dentures must be established during function.
• Tryde in 1965 advocated the use of the closed-mouth technique for making many compressive impressions. Movements of the oral cavity are recorded as they would in normal physiological activities such as swallowing, chewing, and talking.
• A preliminary impression is made with the compound.
• The special tray is made with a periphery short by 1/8th inch.
• A secondary impression is made in this tray with the compound.
• Bite rims with a uniform occlusal surface are made.
• The impression is softened and reinserted in the mouth and held against biting pressure for 1-2 mins.
• Borders are molded by asking the patient to perform functional movements such as whistling,
  smiling, etc. PPS is recorded by swallowing movements under biting pressure.

Alveololingual sulcus Advantages

• Borders are recorded in their functional positions and not rest positions hence dentures will be better retained and not dislodged during functional movements of jaws.
• A positive posterior palatal seal is obtained.

Alveololingual sulcus Disadvantages

• The amount of pressure applied is too great.
• Pressure applied to tissues like incisive papilla, mid-palatine raphe, and peripheral tissues, which are not suited for receiving maximum biting load, results in transient ischemia.

Alveololingual sulcus Minimal Pressure/Mucostatic Theory

• Discovered by Harry L Page in 1938.
• Oral tissues are not distorted nor under stresses of any type but maintained in an undisplaced
  or normal relationship.
• The impression material used in this theory is softer than the softest denture-bearing tissue placed in a custom-made tray that does not impinge on tissues in any area and seated without pressure.
• The tray settles while the patient’s mouth is completely relaxed giving the most accurate reproduction of the bearing area at rest.

Selective Pressure Theory

• Advocated by Carl O Boucher.
• Combines principles of pressure and minimal pressure.
• Importance is given to tissue preservation combined with mechanical factors of achieving retention through minimum pressure which is within the physiologic limits of tissue tolerance.
• Certain areas of the maxilla and mandible are by nature better adapted to withstand the masticatory loads.
• Equilibrium between resilient and non-resilient tissue is created using spacer and reliefs.

Selective Pressure Theory Advantage

The physiologic functions of basal seat tissues are considered.

Selective Pressure Theory Disadvantages

• Difficult to record areas with varying pressure.
• Some areas are recorded under function, hence the potential danger of tissue rebounding and subsequent loss of retention.

Question 67. Functional impression technique.
Answer:

Functional impression technique Material Used

Tissue conditioners.

Functional impression technique Advantages Of Tissue Conditioners

• Good for refitting complete dentures with ease.
• Retaining compliance for many weeks.
• Good dimensional stability.
• Good bonding to the resin denture base.

Functional impression technique Indications For Relining

Lack of retention.

Hyperemic mucosa with sore spots in the denture-bearing mucosa (for tissue conditioning).

Functional impression technique Factors to be Checked Before Tissue Lining

• Peripheral reduction or extension
• Posterior palatal seal extension
• Amount of ridge resorption
• The vertical dimension of occlusion.
• Centric relation, esthetic and artificial teeth for abrasion and wear.

Functional impression technique Procedure

• The tissue surface of the denture is reduced uniformly at least 2 mm to create space for the liner material.
• A treatment liner is placed inside the denture and allowed to flow while all the molding procedures as asking the patient to move the mandible to and fro and other steps are carried out.
• The lining material should flow evenly to cover the whole impression surface and the borders of the denture with a thin layer without voids. An excess of thick material in the border can go unsupported. Hence adequate border extensions are to be done before lining the denture.
• The patient’s mandible is guided into a retruded position, of maximum intercuspation, to help stabilize the denture while the lining material is set.
• Excess material is trimmed away with a hot scalpel.
  The setting progress through plastic and then elastic stages before hardening, which takes several days.
• The plastic stage permits movement of the denture base or bases so they are more compatible with the existing occlusion and also allows the displaced tissues to recover and assume their original position.

Functional impression technique Instruction for Patient

Simple rinsing and gentle brushing with a soft toothbrush minimize damage to the lining. No chemical agents should be used of cleaning the denture.

Functional impression technique Clinical Reline

• After 10 to 14 days when the material is firm enough clinical reline can be done. Before clinical reline the tissue surface is examined to evaluate the health of mucosa.
• If the temporarily relined denture is well retained, with well-rounded peripheral borders and a healthy-appearing mucosa then clinical reline can be done.
• If the surface or peripheral deterioration is slight after tissue conditioning then these areas can be trimmed with a carbide bur and the denture surface can be prepared for a wash, impression with a light-bodied material.
• The stone cast must be poured immediately after the removal of the relined denture base from the mouth.
• Maxillary casts may have to be scored in the selected posterior palatal seal area, since the long period of plasticity of the material may not create sufficient displacement action in this area.

Functional impression technique Rerecording Centric Relation

A new CR record and remount procedure are needed.

Functional impression technique Chairside Technique

• Both the static technique and the functional impression technique are good techniques in cases for simple situations and complicated situations such as excessive tissue changes.
• The chairside technique was uncommon due to chemical burn on the mucosa; a bad odor; lack of color stability of the lined acrylic and if the denture was not positioned correctly, the material was difficult to remove.
• The use of Visible Light-Cured (VLC) resin systems as substitutes for the liner was a better choice of material than acrylic cause of many of its advantages.
• Advantages are a good fit, strength, ability to polymerize without residual components, ease of fabrication and manipulation, patient acceptance, ability to bond with other denture base resins and low bacterial adherence.

Question. Spacer designs in a complete denture.
Answer:

The selective pressure technique which was proposed by Carl O. Boucher combines the principles of both pressure and minimal pressure technique. Selective pressure can be achieved either by scraping the primary impression in selected areas or by fabrication of a custom (special) tray with a proper spacer design and escape holes (relief).

Various Spacer Designs

Design by Roy Mac Gregor: Place a sheet of metal foil in the region of the incisive papilla and mid-palatine raphae. Other areas that may require relief are maxillary rugae, areas of mucosal damage, and the buccal surface of the prominent tuberosities.

Various Spacer Designs Design by Neill: Recommends adaptation of 0.9 mm casing wax all over except the PPS area.

Various Spacer Design by Heartwell: Two techniques:

1. In the first technique, the primary impression is made with an impression compound in a nonperforated stock tray. The borders are refined and space is provided in selected areas by scraping the impression compound.
2. In the second technique, a custom tray is fabricated (but did not mention the wax spacer). Border molding is done with a low-fusing compound. Five relief holes are placed on the palatal region. Three holes in the rugae area and two in the glandular region before making the secondary impression with ZOE paste.

Various Spacer Design by Boucher: 1 mm base plate wax is placed on the cast except for the posterior palatal seal (PPS) area as the PPS area will act as a guiding stop to position the tray properly during the impression procedure. Escape holes are also made with a No. 6 round bur in the palate.

Various Spacer Design by morrow, rudd, Rhoads: Undercut areas are blocked out with wax and a full wax spacer is adapted 2 mm short of the resin special tray border all over. Three tissue stops of 4×4 mm are placed equidistant from each other.

Various Spacer Design by Sharry: A layer of base plate wax is adapted over the whole area outlined for the tray
(even in the PPS area). Four tissue stops of 2 mm width are located in the molar and cuspid region which extended from the palatal aspect of the ridge to the mesiobuccal fold and one vent hole in the incisive papilla region before making the final impression with the metallic oxide
impression material.

Various Spacer Design by Bernard: A layer of pink base plate wax of 2 mm thickness is attached to the areas of the cast that usually have the areas of the softer tissues. The wax spacer is placed all around except in the posterior part of the palate which are at right angles to the occlusal forces.

Various Spacer Design by Sheldon: Describes two techniques

• In the first technique, the primary impression is made with low fusing modeling compound. The borders are refined with a green stick compound. Once the operator is satisfied with the retention, selective relief is accomplished by scraping in the region of the incisive papilla, rugae, and mid-palatal areas.
• In the second technique, a primary impression is made with an alginate primary impression. A primary cast is poured. After analysis of cast contours, undercuts are blocked out. Then placement of the spacer or pressure control (but did not mention the wax spacer design) is done. Border molding is done with green stick compound before making the secondary impression with ZOE paste.

Various Spacer  Design by Halperin: Recommends the ‘Philosophy of the custom impression tray with peripheral relief’. According to this, the slopes of the ridges are considered to be the primary stress-bearing areas and therefore these areas are functionally loaded with compound during the making of the final impression. In this technique, wash secondary impression is not made as
the tray surface and the border-molded areas are considered the final impression surface.

Various Spacer  An Alternative Custom Tray Design By Shetty Sanath Et Al (Jips, Vol. 7, Issue 1, 2007)

A thin sheet of wax 0.4 mm major connector wax is placed in all the areas except the posterior palatal seal area. A 1.5 mm modeling wax is adapted on top of the already adapted wax sheet. Modeling wax is removed in the region of the crest of the alveolar ridge and the horizontal plates of the palate, as these are the stress-bearing areas. Tissue stops, which need to be four in number, are located in the canine and molar regions.

Various Spacer  Considerations For The Use Of Alternate Design

• Can be used in patients with healthy basal seat areas.
• In clinical situations where the mucosa over the ridge or the palate is hyperplasic or flabby, severe undercuts, tori, etc.; an additional layer of wax can be added in these regions.
• In cases of inoperable severe hyperplasic tissues over the ridge, an open tray technique is to be followed to obtain maximum relief.

Question. Single complete denture.
Answer:

The single complete maxillary denture opposing all or some of the mandibular natural dentition is the most common situation.

Single complete denture Problems associated with this: Malposed, tipped, or supererupted teeth in the lower arch. Soreness, mucosal changes, and ultimately ridge resorption in the maxillary arch.

Abrasion of the artificial teeth if the acrylic resin is used or the abrasion of natural teeth if porcelain
is used.

Single Complete Denture Diagnosis and Treatment Planning

The final maxillary impression is made and mounted on the articulator using a face bow. The lower diagnostic cast is mounted using a provisional centric interocclusal record made at an acceptable vertical dimension. Eccentric records are made and the condylar elements of the articulator are set.

Single Complete Denture Techniques For Tooth Modification (Swenson)

• The maxillary and mandibular casts are mounted on the articulator, using a provisional centric relation record at an acceptable vertical dimension. A maxillary base is made and denture teeth are set.
• If the lower natural teeth interfere with the placement of the denture teeth, the area is marked with a pencil.
• The natural teeth are then modified using the marked diagnostic cast as a guide. After the occlusal modifications are completed, a new lower arch cast is made and mounted on the articulator. The denture teeth are reset and prepared for the try-in.

Single Complete Denture Other Techniques

Yurkstas involves the use of a metal U-shaped occlusal template that is slightly convex on the lower surface.

Single complete denture By Bruce: The inner surface of the template is coated with a pressure-indicating paste. Interferences are noted through the template and removed by reshaping.

Single complete denture Common Occlusal Disharmonies

Completely edentulous maxillary area opposing mandibular natural teeth with second molars present. These second molars are often severely inclined mesially and their distal halves supererupted.

Single complete denture Correction is done by

1. Grinding the distal half of the occlusal surface and the denture teeth set to occlude only with that area.
2. Crown prepared for second molars.
3. Onlay mesial rest.
4. Orthodontic repositioning of the tilted molars.

Single complete denture Methods Used to Achieve a Harmonious Balanced Occlusion

1. Dynamically equilibrate the occlusion by the use of a functionally generated path.
2. Statistically equilibrate the occlusion using an articulator programmed to simulate the patient’s jaw movement.

Functional Chew-In Techniques

Functional Chew-In Techniques Technique by Stansbury, 1928

• For an upper complete denture opposing lower natural teeth.
• A compound maxillary rim trimmed buccally and lingually for freedom in lateral excursions is used.
• Carding wax is added to the compound rim and the patient is instructed to perform eccentric chewing movements.
• The carding wax is slowly molded to the functional movements, while the compound preserves the vertical dimension.
• Stone is vibrated into the wax paths of the cusps.
• The upper cast is mounted on the articulator with the lower cast.
• One is a duplicate of the lower teeth and the other is a replica of the generated path.
• The denture teeth are first set to the lower cast of the patient’s teeth.
• After the try-in is approved, the lower cast is removed and the lower chew-in cast record is secured to the articulator.
• All interfering spots are ground until the incisal guide pin prevents further closure.

Functional Chew-In Techniques Technique by Vig

A fin of resin is placed into the central grooves of the lower posterior teeth. The resin fin maintains the vertical dimension and also helps diagnostically locate interfering mandibular cusps. In eccentric movements, the lower cusp tips are ground until equal contacts occur between the teeth and the resin. The fin is then built up using a soft wax and a functional path is generated.

Functional Chew-In Techniques Technique by Sharry

Lateral and protrusive chewing movements are made so that the wax is abraded generating the functional paths of the lower cusps. This is continued until the correct vertical dimension has been established.

Functional Chew-In Techniques Technique by Rudd

A thickness of recording matrix made up of 3 sheets of medium and pink base plate wax and two sheets of red counter, wax is added to the buccal and lingual surface of this compound rim.

Functional Chew-In Techniques Articulator Equilibration Techniques

• The upper cast and lower cast is mounted on an articulator by a centric interocclusal record at an acceptable vertical dimension.
• If denture teeth are placed too far from the buccal when articulated with the lower buccal cusps, they are reset to oppose the lower lingual cusps.
• If the denture teeth appear to be placed too far lingually when articulated with the lower lingual cusps, they are reset to oppose the lower buccal cusps.
• If the lower buccal cusps are selected for the holding cusps, the lingual cusps are reduced.
• If the lower lingual cusps are selected for the holding cusps, the buccal cusps are reduced.
• Thus a cusp-to-fossa relationship is achieved.
• If any of the natural teeth are super erupted or tipped, they are modified by selective grinding
  or by restoring with a crown or onlay to attain a proper occlusal plane.
• At the time of the wax try-in, eccentric records are made and the condylar inclinations are set on the articulator with the upper posterior teeth arranged in balanced occlusion.
• After the denture has been processed, it is again related to the mounted lower cast with a new centric interocclusal record.
• Finally, a denture that is in balanced occlusion that allows freedom in lateral excursions while maintaining maximum bilateral contacts in functional and parafunctional activities is made

Functional Chew-In Techniques Occlusal Materials for the Single Denture

Occlusal materials are porcelain, acrylic resin, gold, acrylic resin with amalgam stops, and interpenetrating polymer network resin.

Functional Chew-In Techniques Subsequent Problems with Single Dentures against Natural Teeth

• One of the major problems with dentures opposing natural teeth is abrasion.
• When using maxillary porcelain teeth, will lead to rapid wear of the opposing natural teeth. Gold inlays or crowns and silver alloy restorations wear away more rapidly than tooth enamel when opposed to porcelain complete denture teeth.
• The use of acrylic resin teeth is the best alternative.

Question. Problems associated with a single Complete denture.
Answer:

The major problems associated with a single complete denture are associated with the following:

• Occlusal forces
• Occlusal form of the natural teeth
• Support for the denture base
• Intermaxillary relations.

Complete Denture Occlusal Forces

• These forces have been recorded as high as 198 lbs on a single molar natural tooth whereas the force with a complete denture is only 26 lbs. Hence natural teeth can impart a high force on the opposing complete denture.
• Unfavorable force distribution can cause extensive morphological changes in denture foundation, extreme jaw relationships, and excessively displaceable denture-bearing tissue.

Complete Denture Occlusal Form Of The Natural Teeth

The occlusal form of the remaining natural teeth will dictate the occlusion of the denture. The natural teeth may be over-erupted or tilted and their cusps may be high and sharp. Denture will constantly be thrust or dragged horizontally on the ridge. Hence an occlusal plane correction will be required for eliminating the associated problem.

Complete denture Support For The Denture Base

The denture base should have the maximum extension within the functional anatomic limits. Lower complete dentures opposing upper natural teeth should be normally avoided.

Complete denture Intermaxillary relations

When an upper complete denture is being made to occlude with lower natural teeth, an error may be made in recording the vertical dimension. The labiolingual thickness of the wax rim will usually not allow the lower incisor to close beyond the occlusal surface. Hence an increased vertical dimension may be recorded.

Complete Denture Common Reasons For Fracture Of Denture

• Occlusal stress on the maxillary denture and the underlying edentulous tissue from teeth and musculature of opposing natural dentition.
• The position of the mandibular teeth may not be properly aligned for the achievement of bilateral balance for stability.
• Flexure of the denture base.

Complete denture Considerations to overcome the problems associated with single complete Denture

• Acceptable interocclusal distance.
• Stable jaw relationship with bilateral tooth contact in retruded position.
• Stable tooth quadrant relationships with axially directed forces.
• Multidirectional freedom of tooth contact throughout a small range (within 2 mm) of mandibular movements.