Anatomy and Physiology in Relation to Complete Denture Construction
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Transcript of Anatomy and Physiology in Relation to Complete Denture Construction
Anatomy and Physiology In Relation to Complete Denture Construction
→ The knowledge of oral anatomy and physiology will help the operator and provides enough landmarks to act as positive guide during denture construction.
→ This subject can be discussed under:[ I ] Extra-oral landmarks of prosthetic importance.[ II ] Intra-oral landmarks of prosthetic importance:
a) In the maxilla.b) In the mandible.
[ III ] Border structures that limit the periphery of the denture:a) In the maxilla.b) In the mandible.
[ IV ] Anatomy and physiology of the T.M. J. and mandibular movements.
[ I ] Extra-oral Landmarks Of Prosthetic Importance:Landmark Description Significance
1- Inter-pupillary line
- Imaginary line running between the two pupils of the eye when the pt. is looking straight forward.
- Establishing the anterior Occlusal plane of the artificial teeth of the denture.
2- Ala-tragus line (Camper's line)
- Imaginary line running from the Inferior border of the ala of the nose to the superior border of the tragus of the ear.
- Establishing the posterior Occlusal plane of the artificial teeth of the denture.
3- Canthus-tragus line
- Imaginary line running from the outer canthus of the eye to the superior border of the tragus of the ear.
- Locating the position of the condyles.
4- Naso-labial sulcus
- Depression that extends from the ala of the nose in a downward and lateral direction to the corner of the mouth.
- After extraction of teeth it becomes accentuated and should be restored by complete denture.
5- Vermillion border - The transitional epithelium between the mucous membrane of the lip and the skin.
- After extraction disappears in the upper lip and becomes accentuated in the lower& should be restored by a complete denture.
6- Mento-labial sulcus
- Depression runs horizontally between the lower lip and chin.
- It determines the Angle of Classification:1- Angle class [I]: Normal ridge relationship.2- Angle class [II[: Retruded mandibular position.3- Angle class [III]: Protruded maxillo-mandibular relation ship.
Landmark Description Significance
7- Philtrum - Diamond-shaped area between the center of the upper lip and the base of the nose.
- After extraction of teeth it becomes flattened and should be restored by a complete denture.
8- Modiolus - The point of meeting of facial muscle fibers.
- After extraction of teeth it becomes downwards and should be restored by a complete denture.
9- Angle of the mouth (commissure of the lips)
- Point of meeting between the upper and lower lip.
- (Angular Chilitis): Inflammation and ulceration as a result of:1- Prolonged edentulism.2- ↓ vertical dimension of complete denture.3- Vitamin B deficiency.
Fig.1: A, The Philtrum, naso-labial sulcus, commissure of the lips& mento-labial sulcus.B, Modiolus and Orbicularis Oris muscle.
Fig.2: Profile view showing the relation of the upper and lower anterior teeth and the curvature of mento-labial sulcus.
[ II ] Intra-oral landmark of prosthetic importance:
A- In the Maxilla:Landmark Description Significance
1- Residual ridge - The portion of the alveolar process& it's soft tissue covering that remains after extraction.
- It covers by a dense connective tissue fibers so, it can be act as a 1ry stress bearing area.
2- Maxillary tuberosity
- Bony prominence located posterior to the upper 3rd molar.
- Aid in support, retention and stability of the complete denture.- When it is large:1- Relieved.2- Modify the path of insertion. (unilateral enlargement).3- Surgical removal.
3- Median palatine raphe
- The mucoperiostium that covers the median palatine suture.
- When it is prominent it should be relieved.- Lack of relief cause:1- rocking of the denture due to bone resorption.2- Tissue ulceration.3- Mid-line denture fracture.
4- Incisive papilla - Pear-shaped elevation present in the midline behind the 2 centrals.
- After extraction of teeth it migrates to the crest of the ridge.- It should be relieved to avoid the burning sensation of the palate.
5- Palatine rugae - It is irregular elevations radiates from the midline of the anterior part of the palate.
- 2ry stress bearing area.- Prevent forward movement of the denture.- If it is sensitive or prominent it should be relived.
6- Torus palatinus - Bony prominence present at both sides of the midline of the palate.
- It should be:1- Relieved.2- Surgical removal.
7- Fovea palatinae - Two openings of minor salivary glands present in both sides of the midline posterior to junction of hard and soft palate.
- It determines the posterior extension of the upper complete denture to be 2mm posterior to it.
B- In the Mandible:Landmark Description Significance
Fig.3: A, Diagram of the upper arch.B, Diagram of the lateral surface of the maxilla.
1- residual ridge - The portion of the alveolar process& it's soft tissue covering that remains after extraction.
- Don't used as 1ry stress bearing area → Covered by movable fibrous connective tissue.- Don't Provide stability or support.
2- External oblique ridge
- Bony ridge running downward and forward from ramus to reach mental foramen.
- It is a limiting structure to the complete denture and not extend to it.
3- Buccal shelf area - Bony area extends between the external oblique ridge and the residual ridge.
- Used as 1ry stress bearing area:1- Perpendicular to the vertical masticatory force.2- Formed from compact bone.3- provide support.
4- Mental foramen - It's located on the Buccal surface of the mandible between the roots of 1st and 2nd premolar.
- Lack of relief → numbness of the lower lip.
5- Retromolar pad - Pear-shaped area located distal to the lower 3rd molar.
- Shock absorbent.- Gives retention not support.- Determine the level of the Occlusal plane.
6- Torus mandibularis
- Bony prominence located at the inner surface of premolar area.
- It should be: 1- Relieved.2- Surgical removal.
7- Internal oblique ridge (Mylohyoid ridge)
- Irregular bony ridge of median surface of the mandible which the Mylohyoid muscle attached.
- It should be relieved during complete denture construction.
8- Genial tubercle (Mental spine)
- Two bony projections present at the median surface of mandible at midline of each side of symphesis.
- Represent the attachment of geniohyiod and genioglossus muscles.- If it's prominent, it should be relieved.
[ III ] Border Structures That Limits The Periphery Of The Denture:
Fig.4: Diagram showing the mandible:A, Buccal view.B, Lingual view.