Jcc / orthodontic courses by Indian dental academy

““AN EFFECTIVE AN EFFECTIVE TECHNIQUE FOR TECHNIQUE FOR

DENTURE DENTURE BORDER BORDER

EVALUATIONEVALUATION”” INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.comwww.indiandentalacademy.co

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INTRODUCTION

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MAXILLARY & MANDIBULAR EDENTULOUS FOUNDATIONS: Knowledge of oral anatomy helps the operator in understanding the

landmarks that serve as positive guides in Prosthodontic procedures

.DEFINITION :Denture bearing areas or Denture foundation area or

Basal seat —the surface of the oral structures available to support a denture.(GPT-8)

Denture bearing area- maxilla 24 cm2 & mandible 14 cm2 (Dr WATT surgeon.)

The impression surface/Fitting surface-1.stress-bearing/supporting areas.2.peripheral/limiting areas.


STRESS-BEARING AREA.

• PRIMARY.• Hard palate.(max)• Buccal shelf.

(man)

• SECONDARY.• Rugae .(max).• Slopes of residual

ridge .(man).


Supporting areas. • PRIMARY.• Horizontal portion

of Hard palate .(max)& Rugae

• Buccal shelf (man)

• SECONDARY.• Crest of residual

ridge. (max)• Slopes of residual

ridge. (man)


RELIEF AREAS.• MAXILLA.• Medial palatal

suture.• Incisive foramen.• Sharp bony

projection.• Rugae – valley.

• MANDIBLE.• Crest of residual

ridge.• Sharp bony

projection.• Mental foramen.• Genial tubercle.• Mylohyoid ridge.


Labial frenum: • Fold of mucous membrane

at the median line.• Moves with muscles of lip.• Adequate relief for muscle

activity.• Proper denture seal.• Excessive relief weakens

denture base.

Maxillary arch

•A- correct contour

•B –incorrect contour.

•C- area should have been covered.

Labial notch


Buccal frenum: Single or double folds of

mucous membrane. Broad and fan shaped. Moves with muscles of cheek

during speech and mastication. Adequate relief for muscle

activity-more clearence.

•Maxillary buccal frenum area.

•Denture border contour in buccal frenum area.

Buccal notch


Labial vestibule

• Labial-buccal frenum.• Muco-gingival line-

limits upper border.• Record adequate

depth/width.• Overextension causes

instability/soreness.• Proper contouring

gives optimal esthetics.

•Labial flange


Buccal vestibule• Buccal frenum to

hamular notch.• Record adequate

depth/width.• Improper extension

causes instability/soreness.

Buccal flange


Maxillary tuberosity.• Distal end of denture

must have Coverage-stability/retention.

• Gross enlargement(fibrous or bony –surgical correction.

Area of tuberosity


•Distal to maxillary tuberosity

•Aids in locating posterior palatal seal.

•Overextension causes soreness.

Hamular notch.

Area of hamular notchwww.indiandentalacademy.co

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PPS-the seal area at the posterior border of a maxillary removabledentalprosthesis.(GPT-8)

PPS OR POST PALATAL SEAL 0R POST DAM-The soft tissue along the junction of the hard and soft palates on which pressure with in the physiologic limits of the tissues can be applied by a denture to aid in the retention of the denture. (Winkler)• VIBERATING LINE-an imaginary line across the posterior part

of the palate marking the division between the movable and immovable tissues of the soft palate. this can be identified when the movable tissues are functioning.

• The anterior vibrating line is an imaginary line located at the junction of the attached tissues overlying the hard palate and movable tissues of the immediately adjacent soft palate.(valsalva maneuver –method)

• The posterior vibrating line is an imaginary line at junction of the aponeurosis of the tensor veli palatini muscle and the muscular portion of the soft palate.


Vibrating line: • Junction of movable and

immovable part of soft palate.

• 2mm ant to fovea palatinae.

• Aids to establish PPS.• Distal end of denture at

least to vibrating line.

Post palatal seal area. • From hamular notch to

hamular notch.• Anterior to vibrating line.• Aids in retention.

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Fovea Palatinae.• Bilateral indentations

near the midline of palate.

• Formed by coalescence of several mucous gland ducts.

• Posterior to junction of hard and soft palate.

• Aids in determining vibrating line.


Hard palate• Support for the

maxillary denture.• Primary stress

bearing area- horizontal portion of hard palate lateral to midline.

• Secondary stress bearing area –rugae.


Alveloar ridge

• .

Alveolar groove


• Elevation of soft tissue over the incisive foramen or nasopalatine canal.

• Location : on or labial to ridge.

• Impingement –burning sensation, parasthesia and pain.

• Relief necessary.

Incisive papilla.

•Incisive fossa


Rugae.• Irregular shaped

rolls of soft tissue.• Secondary stress

bearing area.• Should not be

distorted in the impression.


• Extends from incisive papilla to distal end of hard palate.

• Thin mucosal covering and non-resilient..

• Relieve adequately to avoid trauma from denture base.

Median palatine raphae.

Median palatine groove


Labial frenum.• Shorter and wider

than the maxillary frenum.

• Adequate relief for muscle activity (mentalis).

• Proper fit around it maintains seal’.

Mandibular arch.

Labial notch.


Buccal frenum.

• Adequate relief for muscle activity.

• Proper denture seal.

Buccal notch.


Labial vestibule. • Labial-buccal frenum.• Overextension causes

instability/soreness.• Muscles attachment

close to the crest of the ridge- limits the denture flange extension.

• Mucolabial fold limits the depth of the flange.

• Record adequate depth and width.

• Proper contouring gives optimal esthetics.

Labial flange


Buccal vestibule.

• Buccal frenum-retromolar pad.

• Record adequate depth and width.

• Impression is widest in this area.

Buccal flangewww.indiandentalacademy.co

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Buccal shelf• .


Def..Anatomically buccal shelf is defined as the part of the basal seat located posterior to the buccal frenum.(Boucher 10th edition).

• The area between the mandibular buccal frenum and the anterior edges of masseter muscle is known as buccal shelf(b12)

Boundaries:• Anteriorly-buccal frenum.• Posteriorly-retromolar pad.• Medially-crest of the ridge• Laterally-external oblique ridge.Width-4-6 mm wide on average mandible.• 2-3 mm or less in narrow mandible.• The total widthof the bony foundation in this region becomes

greater as alveolar bone resorption continues.the reason is that the inferior border of the mandible is great than the width at the alveolar process.

Clinical implication: upper slopes of the buccal shelf adjacent to the pad helps to resist the distal dis placement of the denture because of the diminished available support,a narrow mandible is usually considered the most difficult to manage.

• Clinically care should be taken to cover the area


• Interpreting the buccal shelf area:While recording the final impression additonal load is applied in this area,the trays comes in to direct cotact with the mucosa.

• Preprosthetic surgery:no• When the residual ridge becomes flat the

buccinator is often attached to the center of the ridge.the buccinator muscle can be covered by the denture in this area because the muscle fibres run anterioposteriorly parallel to the bone and the denture does not resist the contracting forces of the muscles.the inferior part of the buccinator is attached to the buccal shelf of the mandible and the contraction of the muscle doesnot lift the denture.(resorbtion

• Resisted by horizontal fibres of buccinator


Histology: mucous membrane-is more loosely attached and less keratinised than the mucous membrane covering the crest of the ridge.

• Submucosa:thicker,fibres of buccinator are found running horizontally in the submucosa immediately overlying the bone.

• The mm overlying the buccal shelf may not be suitable histologically to provide primary support for the denture as the mm overlying the crest of the ridge.

• Bone:bs is covered by layer of smooth compact boneor cortical bone(with it’s haversian system,the bone is very dense and the trbaculae are arranged almost at right angles to the jaw closure) plus the fact that the bucal shelf lies at right angles to the vertical occlusal forces,therfore it is more suitable primary stress bearing area for the lower denture.


• Blood supply—artery supply—buccal artery,inferior alveolar artery,nerve supply—buccal nerve ,inferior alveolar nerve,buccal branch of mandibular nerve.

• Oralucousmembrane thick ness--mucous membrane-is more loosely attached and less keratinised than the mucous membrane covering the crest of the ridge.

• Muscle found in this area—inferior part of the buccinator,anterior edge of the masseter muscle.


External oblique ridge.• A bony ridge runs

antero-posteriorly outside the buccal shelf.

• Denture border 1-2 mm beyond this ridge.

• Shows as Groove in impression.


Alveolar ridge• Residual bone with

mucous membrane.• Crest to be

relieved.• Buccal and lingual

slopes are secondary stress bearing areas.


Retromolar pad.• Triangular soft pad of

tissue.• Posterior end of lower

edentulous ridge.• Limiting landmark of distal

extension of complete denture upto ant 2/3 rd of retro molar pad.

• Determines height and width of the occlusal table.

• Contents-loose connective tissue, glandular tissue ,laterallybuccinator,posteriorly temporalis tendon, medially superior constrictor and pterygo mandibular raphe

Retromolar fossa


Alveolo-Lingual sulcus.• Between lingual frenum to

retromylohyoid curtain.• Anterior region- • Premylohyoid fossa-

premylohyoid eminence in impression.

• Border of Impression to make contact with the mucosa of the floor of the mouth when tongue touches the upper incisor.

• Overextension causes soreness and instability.Lingual flange

Premylohyoid eminence


Middle region.• From pre-mylohyoid

fossa to the distal end of the mylohyoid ridge.

• Lingual flange extends below the level of the mylohyoid ridge- tongue rests on the top of flange and aids in stabilizing the lower denture.

• To record ask the patient to touch the buccal mucosa on either side of cheek with tip of the tongue.


Posterior region.• The flange

passes into the retromylohyoid fossa.

• Proper recording gives typical S –form of the lingual flange.


Retromylohyoid fossa.• Distal end of lingual

sulcus.• Area posterior to the

mylohyoid muscle.• Good seal aids in

retention and stability.• To record –ask the

patient to protrude the tongueRetromylohyoid eminence


BOUNDARIES OF LATERAL THROAT FORM. • Anteriorly –mylohyoid muscle • Laterally –pear shaped pad • Posteriolaterally-superior constrictors and• Posteromedially –palatoglossus• The posterior limit of the mandibular

denture is determined mainly by the palatoglossal muscle and by superior constrictor muscle-this area is called as retro myelohyoid curtain.


Mylohyoid ridge.• Attachment for the

mylohyoid muscle.• Sharp or irregular

covered by the mucous membrane.

• Trauma from denture base –relief necessary.


Mylohyoid muscle.• Floor of the mouth is

formed by mylohyoid muscle.

• Lies deep to the sublingual gland in the anterior region- does not affect the border of denture.

• Posterior region –affects the lingual border in swallowing and tongue movements.


Genial tubercle.• Area of muscle attachment

(Genioglossus and Geniohyoid).

• Lies away from the crest of the ridge.

• Prominent in Resorbed ridges.

• Adequate relief to be provided.


JANKELSON in 1962-Adjustments necessary

1.DYNAMIC PHYSIOLOGY2.FACTORS WITH MATERIALS &TECHNIQUES

PRESSURE AREAS-1.Basal surface 2.Intaglio surface 3.Denture peripheries


Common methods of border evaluation

Visual &tactile methodMethods employing indicator

pasteDisclosing wax methods


VISUAL-TACTILE METHOD

• Experienced operators• Selective activation of facial

musculature/tipping forces to denture• Identify areas of over extension/under

extension• Disadvantage-subjective& lead to over

adjustment/modification


Indicator paste• Pressure areas on intaglio surface&

not used for border evaluations• Low viscosity &displaced by

functional movements• Disadv-cannot built appreciable

thickness without distortion so, not used for under extension


Disclosing waxes• Exhibit higher viscosities than

indicator paste , it can with stand greater loads without complete displacement so, they built up to thickness

• Modification with silicone gels/petrolatum


TECHNIQUE


CONCLUSION



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Jcc / orthodontic courses by Indian dental academy

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