GOOD MORNING

SEMINAR ON

SIGNIFICANCE OF MAXILLARY DENTURE BEARING AREA AND RELATED ANATOMY

PRESENTED BY DR NARAYAN SUKLA

1ST YEAR PG DEPART MENT OF PROSTHODONTIA

- Introduction- bony structures - mucous membrane - limiting structures - supporting structures - relief areas-conclusion- reference

Introduction The anatomical significance and the anatomy of

the edentulous ridge in the maxilla and mandible is very important for the design of a complete denture

Our objective in fabrication of a complete denture is to provide for a prosthesis that restores lost teeth and associated structures functionally, anatomically and aesthetically as much as possible with preservation of underlying structures and the knowledge landmarks help us in achieving our objective.

osseous structures· The osseous

structures not only support the denture but also have an direct bearing on impression making procedure.

· Maxillary denture is supported by two pairs of bones, maxillae & palatine bone.

Boucher pg no 148 fig

Mucous Membrane· Mucous membrane

serves as a cushion between the denture base and supporting bone.

· Mucous membrane is composed of mucosa and sub mucosa.

· Sub mucosa is formed by connective tissue that varies from dense to loose areolar tissue and varies in thickness.

------compact bone

---------periosteum

-------sub mucosa

--------mucosa

Mucous Membrane· Thickness and consistency of the sub

mucosa are responsible for the support that the mucous membrane affords a denture, because the sub mucosa makes up the bulk of mucous membrane.

· In healthy mouth the sub mucosa is firmly attached to the periosteum of bone and will withstand the pressure of dentures.

· If sub mucosa is thin, soft tissue will be non resilient and mucous membrane will be easily traumatized.

According to the clinical significanceLandmarks

of edentulous jaws

Limiting structures

Supporting structures

Relief areas

Limiting structures

These are the sites that will guide us in having an optimum extension

of the denture so as to engage maximum surface area without encroaching upon the muscle actions

Encroaching upon these structures will lead to dislodgement of the denture and/or soreness of the area while failure to cover the areas upto the limiting structure will imply decreased retention stability and support.

Labial frenum It is a fold of mucous

membrane at the median line It contain no muscle fiber and

has no action of his own

CLINICAL SIGNIFICANCE Sufficient allowance should be

created in final impression and in complete denture prosthesis

If the frenum is attached close to the creast frenectomy should be done

The labial notch of the denture should be narrow but deep enough to avoid interference

Labichal notch

Labial vestibule Labial vestibule (sulcus)-The part of the

oral cavity which is bounded on one side by the teeth, gingiva and residual alveolar ridge and on the outer side by lips. It runs from one side of the buccal frenum of one side to the other side ;dividing in two compartments-left and right by the labial frenum

This area is covered by non keratinized epithelium with areolar tissue

CLINICAL SIGNIFICANSE The outer surface of the labial vestibule is

the orbicularis oris.* Its fibers run in a horizontal direction; so it has an indirect effect on the denture base

Reflection of the m m superiorly marks the height

The area of reflection has no muscle attachment

Due to this the tissue in this region is movable and lead to over extension

Overextension causes instability/soreness.

•Labial flange

Buccal frenum Single or double folds of mucous

membrane. Broad and fan shaped. The buccal frenum is the dividing line

between the labial & buccal vestibules. It is related to three muscles, so it requires more clearance than the labial frenum

Buccal frenum-Attachment of following muscles;levator anguli oris,orbicularis oris,buccinator.

· The caninus ( levator anguli oris) attaches beneath and affects its position

· The orbiculeris oris pulls the frenum forward and buccinators pulls backward

CLINICAL SIGNIFICANCE Moves with muscles of cheek during

speech and mastication. During final impression and in prosthesis

clearance should be created for the movement of the frenum overriding will cause pain and dislodgement of denture

During impression the cheeck should be reflected laterally and posteriorly

If the frenum is close to the creast of the ridge frenectomy should be done

Buccal notch

Buccal vestibule (sulcus) Extends from anteriorly buccal frenum

to the hamular notch posteriorly. Laterally by buccal mucosa, medially by the residual alveolar ridge

The size of the vestibule is dependant upon- contraction of buccinator muscle

position of the mandible amount of bone loss CLINICAL SIGNIFICANSETo record maxillary buccal sulcus, the

mouth should be half way closed The size & shape of distal end of buccal

flange depend up on movement of ramus of mandible at the disital end of the buccal vestibule

Hence the patient move the mandible in a lateral protrusive relation so that coronoid process dose not interfere with these function

Improper extension causes instability/soreness

Buccal flange

The pterygomaxillary (hamular) notch It is depression situated between the

maxillary tuberosity and the hamulus of the pterygoid plate .It is a soft area of loose connective tissue.

clinical significance Used as a boundary of the posterior

border of maxillary denture In cases showing gross alveolar

resorption the hamular notch disappear, so the back edge of the denture is not carried too far

The denture border should extend till hamular notch

Aids in achieving posterior palatal seal area

Over extension cause soreness Underextention cause poor retention

Posterior palatal seal area[post dam]-

Soft tissue at or along the junction of the soft and hard palate on which the pressure within the physiological limits of the tissue can be applied by a denture to aid in the retention of the denture

Made of two regions·→1.Pterygomaxillary seal-The part of the

posterior palatal seal that extends across the hamular notch. It extends 3-4 mm anterolaterally to end in the mucogingival junction on the posterior part of the maxillary ridge.

2.Posterior palatal seal-This is a part of the posterior palatal seal area that extends between the two maxillary tuberosity

Posterior palatal seal area[post dam]-Clinical significance Reduces the tendency for gag reflex due to

downward movement of the denture during incising

.it maintains contact of denture with soft tissue during functional movements of stomatognathic system, by which it decreases gag reflex. . Decreases food accumulation with adequate

tissue compressibility. Decrease patient discomfort of tongue with posterior part of denture. Compensation of volumetric shrinkage that

occurs during the polymerization Increases retention and stability by creating partial vacuum. Increased strength of maxillary denture base.ref JIADS VOL -1Issue 1 Jan-March,2010 |20|

Supporting structuresMasticatory forces produce quite a

pressure on the underlying structures and not everyplace beneath the denture can take such stress hence we need to

know the areas which can bear the stresses well.

Support is the resistance to the displacement towards the basal tissue or underlying structures. These can be divided into-

1.Primary stress bearing area2.Secondary stress bearing area

Supporting structures

Primary stress bearing area Secondary stress bearing area 1.The horizontal portion of 1. the rugae area the hard palate 2.maxillary tubeorcity

lateral to themidline –posterolateral slopes2.Slopes of residual alveolar ridge

Primary stress bearing areaThese are the areas that are most

capable to take the masticatory load providing a proper support to the denture.

Some desired properties for primary stress bearing area are-

1.Tightly adherent sufficient fibrous connective tissue with an overlying keratinized mucosa

2.Presence of cortical bone cover3.Should be at right angles to the

vertical occlusal forces.4.No underlying structures should

be present that will get harmed due to stress

Primary stress bearing areaHard Palate- The anterior region of the hard

palate is formed by the palatine selves of maxillary bone

- The posterior part is formed by horizontal part of palatine bone

- Covered by keratinized stratified squamous epithelium

- Anterolaterally, the sub mucosa contains adipose tissue.

- Poster laterally, it contains glandular tissue.

Clinical significance- The horizental portion of the hard

palate provides the primary stress-bearing area.

Residual alveolar ridge The portion of the residual

bone , soft tissue covering that remains after the removal of teeth .

The residual ridge consist of mucosa sub mucosa periosteum and the residual alveolar bone

Clinical significance It is the foundation of

denture It is the primary stress

bearing area

Secondarystressbearingarea rugae areaRaised areas of dense connective

tissue radiating from the median suture in the anterior 1/3rdof palate

· It consists of series of ridges in the anterior part of the hard palate

· Sets at an angle to residual ridge & covered by thin soft tissues

Clinical significanse· It is considered as a secondary

stress bearing area· Should not be distorted in the

impression.

Maxillary Tuberosity It is the bulbus extension of the

residual ridge in the 2nd and 3rd molar region

It is the distal aspects of the posterior ridge terminating in the hamular notch

Clinical significance The medial & lateral walls resist the

horizontal and torquing forces which would move the denture base in lateral or palatal direction.

Therefore, maxillary denture base should cover the tuberosities and fill the hamular notches.

Gross enlargement(fibrous or bony –surgical correction.

Area of tuberosity

Relief areaThese are the areas which either

resorb under constant load or have fragile structures within or are covered by thin mucosa which can be easily traumatized

& hence should be relieved. Incisive papilla Mid palatine raphae fovea palatinae

Incisive papilla

Incisive papilla is a mass of fibrous tissue about 1cm behind the upper incisors.

It is an exit point of nasopalatine nerves and vessels

clinical significance Its position in the edentulous mouth

indicates where the incisors and canines should be set.

It should be relieved failure of which would result in necrosis of the distributing areas and paresthesia of anterior palate. burning sensation and pain.

Denture base should be relieved over the area to avoid pressure to the nerves & blood vessels.

Mid palatine raphe

Median suture area covered by thin sub mucosa

Extends from incisive papilla to distal end of hard palate.

In the region of medial palatal suture , the sub mucosa is extremely thin ; so relief should be provided to avoid trauma or rocking of the denture

Clinical significance Relief is to be provided as it is

supposed to be the most sensitive part of the palate to pressure

Relieve adequately to avoid trauma from denture base. Median palatine groove

Fovea Palatina Bilateral indentations near the

midline of palate. Posterior to junction of hard and soft palate.

These are a pair of mucous gland duct orifices near the midline at the junction of the hard and soft palate.

Formed by coalescence of several mucous gland ducts.

clinical significance Aids in determining vibrating line. These landmarks provide a guide to

the position of the posterior palatal border of a denture

Conclusion

Thus, we see that a sound knowledge of the anatomical landmarks of the edentulous jaw is a prerequisite if one

has to achieve the objective one has in mind; fabrication of a complete denture that has maximum retention, stability and support with preservation of underlying structures with minimum post insertion problems.

References

Boucher's Prosthodontics Essential of complete denture

prosthesis by Sheldon Winkler Clinical dental prosthetics by h r b

fenn

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