Mandibular Intra-Oral Landmarks Lecture PDF

Faculty of Dentistry Removable Prosthodontics Division Lecture : Mandibular Intra oral landmarks Dr.: Reham El sharabasy Date : 28/10/2024  Border structures that limit the periphery of the denture base(Limiting structures) The Peripheral Seal The Peripheral Seal  Mandibular limi...

Faculty of Dentistry Removable Prosthodontics Division Lecture : Mandibular Intra oral landmarks Dr.: Reham El sharabasy Date : 28/10/2024  Border structures that limit the periphery of the denture base(Limiting structures) The Peripheral Seal The Peripheral Seal  Mandibular limiting structures 1. Labial Frenum Denture should be notched opposite to it. Mandibular limiting structures 2. Labial vestibule Limits the denture flange thickness and length.  Mandibular limiting structures 3. Buccal Frenum It is a fold of mucous membrane in the premolar area. Movement of the lip and the cheek move the frenum. A notch is made in the lower denture to accommodate the frenum.  Mandibular limiting structures 4. Buccal Vestibule The denture in this area is related to the buccinator muscle. Its contraction does not displace the lower denture so flanges of the lower denture must extend in the buccal vestibule.  Mandibular limiting structures 5. Masseter muscle influencing area (Masseteric Notch) The distobuccal flange of the denture should be contoured to allow freedom for this action otherwise the denture will be displaced or the patient will experience soreness in this area.  Mandibular limiting structures 6. Posterior end of retromolar pad It constitutes the posterior limit of the lower denture at which postdamming can be performed.  Mandibular limiting structures 7. Palatoglossal arch Disto-lingual border of lower denture is related to the palato-glossal Distolingual area arch which is formed mainly by the palato- glossal muscles Denture overextension in this area will cause sore throat.  Mandibular limiting structures 8. Lingual Pouch Lingual Pouch Lingual pouch Posteriorly : The palatoglosssus muscle. Anteriorly : The Mylohyoid muscle. Medially : The tongue. Laterally : The medial aspect of the mandible.  Mandibular limiting structures 9. Mylohyoid muscle influencing area (internal oblique ridge) Mylohyoid muscle influencing area Mylohyoid muscle influencing area  Mandibular limiting structures 10. Sublingual salivary gland area Sublingual salivary gland area Sublingual salivary gland area The lingual flanges of the lower denture should not extend in this area because with excessive resorption of the mandible the gland may bulge superiorly above the body of the mandible.  Mandibular limiting structures 11. Lingual Frenum More anteriorly a fold mucous membrane attach the mucosa of the undersurface of the tongue to mucosa of the floor of the mouth. It moves with the movement of the tongue so a notch is made to accommodate the frenum.  Mandibular limiting structures 6. Retromolar 7. Palatoglossus arch pad 8. Lingual pouch 5. Masseteric notch 9. M.M,influencing a. 4. Buccal vestibule 10. sublingual salivary gland a. 3. Buccalfrenum 11. Lingual frenum 2. Labial vestibule 1. Labial frenum Mandibular intra-oral landmarks 1- Residual alveolar ridge: It is that portion of the alveolar process that remains after extraction of teeth. The highest part of the ridge is called the crest of the ridge. It is formed of cancellous bone. Sometimes, in severe resorption, it appears as flabby tissue. This case necessitates special impression technique or surgical intervention as it impairs denture stability. Mandibular intra-oral landmarks 2. External Oblique ridge : It is a dense bony ridge descending obliquely from the ramus of the mandible downward and forward till it fades at the mental foramen. The lower denture should cover but not extend beyond EOR to avoid denture displacement by the masseter ms. Mandibular intra-oral landmarks Buccal shelf 3. Buccal Shelf of bone: It is bordered externally by the external oblique line and internally by the slope of the residual ridge. This region is a primary stress bearing area in the mandibular arch because it is parallel to the occlusal plane and the bone is. very dense. Mandibular intra-oral landmarks 4. Mental Foramen: The anterior exit of the mandibular canal and the mental nerve. In cases of severe residual ridge resorption, the foramen occupies a more superior position. The denture base must be relieved to prevent nerve compression and pain and cause numbness of the lower lip. Mandibular intra-oral landmarks 5. Retromolar pad: It is pear shaped pad of soft tissue present bilaterally at the distal end of the residual ridge. It contains mucous glands, tendons, and muscle fibers. It should be covered by the lower denture to help for denture retention. Act as a cushion Mandibular intra-oral landmarks 6. Torus mandibularis: It is a bony prominence sometimes present on the inner surface of the mandible in the premolar region. It varies in size and shape. Relief of the denture base in this area could be made to avoid impingement of the mucosa. If the torus mandibularis is large and prevents proper seating of the lower denture, surgical intervention is necessary. Mandibular intra-oral landmarks 7. Mylohyoid ridge: It is a bony ridge extending on the medial surface of the mandible from the third molar region to the lower border of the mandible near the midline.  Moderate resorption Dentate Mandible-No resorption Note the position of the mylohyoid ridge as it varies with the degree of alveolar ridge resorption. Severe resorption Mylohyoid ridge Mandibular intra-oral landmarks 8. Genial tubercles: present on the medial surface of the mandible and serve as the attachment sites of the genioglossus and geniohyoid muscles. In patients’ with severe ridge resorption they may cause discomfort if they are exposed to the denture base.