By: Dr. Ahmed Rabah
Oral cavity landmarks
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: In the maxilla. In the mandible. III. Border structures that limit the periphery of the denture: In the maxilla. In the mandible. IV. Anatomy and physiology of the T.M.J.
Landmark Description Significance
Angle s class II Angle s calss I Angle s class III Inter-pupillary line
1. In the maxilla (supporting structures)
2. In the mandible (supporting structures) Landmark Description Significance
Complete denture limiting structures
1. Labial frenum 2. Labial vestibule 3. Buccal frenum 4. Buccal vestibule 5. Coronoid bulge 6. Residual alveolar ridge 7. Maxillary tuberosity 8. Hamular notch 9. Posterior palatal seal region 10.Foveae palatinae 11.Median palatine raphe 12.Incisive papilla 13.Rugae area
Landmark Description Significance 1. Maxillary labial frenum Is a fold of mucous membrane extending from mucosa of the lip and attached near the crest of the ridge. It produces the maxillary labial notch in the denture border. 2. Maxillary labial vestibule (labial sulcus) It is the part of the oral vestibule that lies between the maxillary ridge and the lips. It extends from the maxillary labial frenum on both sides of the midline. It is occupied by the labial flange of the denture. The denture flange in this area is in relation to orbecularis oris and incisivus labii superioris muscles which determine the length and thickness of the labial flange. 3. Buccal frenum It is a fold of mucous membrane that varies in size, number and position. It overlies the canninus muscle 4. Buccal mucous membrane reflection area (buccal vestibule) 5. Pterygo-maxillary notch (hamular notch) It is the reflection of mucous membrane from the cheek to the alveolar ridge distal to the buccal frenum. The denture border in this area is in relation to buccinator muscle which limits the height and thickness of the denture border. It is a narrow cleft between the maxillary tuberosity and the peterygoid hamulus and filled with connective tissue. 6. Soft palate - It is the posterior border of the upper denture. - It has two parts (immovable part and movable part). - The area of the posterior palatal seal should be located at the junction between these two parts. It is called vibrating line or Ah line. It produces the maxillary buccal notch in the impression or the denture to facilitate functional movement. It represents the maxillary buccal flange of the denture. - It determines the posterior extension of the denture. - the posterior palatal seal is responsible for the posterior retention of the denture.
Landmark Description Significance 1. Mandibular labial frenum 2. Mandibular labial vestibule (labial sulcus) Is a fold of mucous membrane (contains no muscles) and extending from mucosa of the lip to the mucosa of the alveolar process at the mid line. It is the reflection of the mucosa of the lower lip to the mucosa of the alveolar process. 3. Buccal frenum - It is a fold of mucous membrane in the premolar area attaching the lip to the alveolar ridge. - It overlies the triangularis muscle. 4. Buccal mucous membrane reflection area (buccal vestibule) 5. masseter muscle influencing area 6. Reteromolar pad and anterior border of the ramus - It is the refelction of the mucosa of the cheek to the mucosa of the alveolar process - It is in relation with the buccinator muscle. The buccal flange should rest on the attachment of the buccinator muscle. It is the disto buccal corner of the mandibular denture which is in relation to the masster muscle - It is a mass of tissue at the distal end of the ridge containing glands, the pterygomandibular raphe fibers of the buccinator muscle and the temporal tendon. 7. Lingual frenum It is a fold of mucous membrane extending along the floor of the mouth to the under surface of the tongue in the midline. It produces the mandibular labial notch in the denture border. It is occupied by the labial flange of the denture. The denture flange in this area is in relation to orbecularis oris and incisivus labii inferioris muscles which determine the length and thickness of the labial flange. It produces the mandibular buccal notch in the impression or the denture to facilitate functional movement. It represents the mandibular buccal flange of the denture. Buccal flange must converge in a medial direction to avoid displacement due to contraction of the masseter muscle - The denture must cover it. It produces a lingual notch in the impression or the denture.
Muscles of Mastication Temporalis Muscle Origin: Temporal fossa Insertion: Coronoid process and anterior border of ramus Function: 1. Elevates and retracts mandible 2. Clenches teeth
Masseter muscle Origin: Superficial portion: anterior 2/3 of lower border of zygomatic arch Deep portion: medial surface of zygomatic arch Insertion: Lateral surface of ramus, coronoid process, and angle of mandible Function: - Elevates mandible. - Clenches teeth
Medial pterygoid muscle Origin: Medial surface of lateral pterygoid plate Insertion: Posterior and lower part of medial surface of ramus, angle of mandible Function: Elevates, protrudes and latero-trudes the mandible. Clenches teeth Lateral pterygoid muscle Origin: Superior head: infratemporal surface of greater wing of sphenoid bone Inferior head: lateral surface of lateral pterygoid plate Insertion: Anterior portion of condylar neck and articular disc Function: Protrudes and laterotrudes the mandible. Pulls articular disc forward