Anatomic Landmarks 1 PDF

Anatomic Landmarks 1 Extra oral Anatomical landmarks Anatomical structure Description Prosthetic value 1. Nasolabial Sulcus A crease that extends Affected by: laterally and downwards – Proper positioning of anterior...

Anatomic Landmarks 1 Extra oral Anatomical landmarks Anatomical structure Description Prosthetic value 1. Nasolabial Sulcus A crease that extends Affected by: laterally and downwards – Proper positioning of anterior from the ala of the nose to teeth. the corners of the mouth that – Proper establishment of becomes more prominent occlusal vertical dimensions. with aging. – Thickness of the denture flange. 2. Mentolabial Sulcus Runs from side to side Its curvature indicates the horizontally between the character of the lower lip and the chin. maxillomandibular relationship. Obtuse in class I Acute in class II Flat in class III 3. Nasolabial Angle Angle between columella of Normally, approximately 90 as nose & philtrum of lip viewed in profile 4. Philtrum A diamond shaped area at the Affected by center of the upper lip and – Proper positioning of anterior base of the nose. teeth. – Thickness of the denture flange. – loss of teeth and resorption of the labial alveolar boneflattened 5. Vermillion Border It is the transitional Affected by epithelium between the – Proper positioning of anterior mucous membrane of the lips teeth. and the skin. – The bulk of the orbicularis oris muscle. – loss of teeth and resorption of labial alveolar bone orbicularis oris loses its support and drops inward (palatally)  diminution Dr. Wafaa Ibrahim Page 1  Anatomic Landmarks 1 of amount of vermillion border showing on the upper lip and relative fullness of the lower lip. 6. Angle of the Mouth It is the point of meeting – Denture should support the between the upper and lower mouth angle. lip at corners of the mouth – Lack of proper support of the upper lip and a reduced vertical dimensionangular cheilitis that is fissuring and inflammation of the angle of the mouth as a result of a continuous wetting from saliva 7. Modiolus Located at the meeting place of the buccinator and other – With the loss of teeth, the facial muscles near the angle modiolus is displaced giving the of the mouth. appearance of an edentulous person (sunken cheek). – The buccal surface of the premolar region of the lower denture must be thin to avoid the modiolus lifting the denture. 8. Interpupillary line An imaginary line running – Aids in orientation of the between the two pupils of the anterior occlusal plane of eyes when the patient is artificial teeth. looking straight forward. – This parallism allows vertical force transmission to the supporting tissues. Any deviation from this parallism will place non vertical forces which are damaging to the tissues. 9. Ala-tragus line An imaginary line running – Aids in orientation of the (Camper’s Line) from the ala of the nose to posterior occlusal plane of the tip of tragus of the ear. artificial teeth. – This parallism allow the masticatory force to be directed at right angle to the ridge 10. Canthus tragus line Imaginary line running from It is used to arbitrarily to locate outer canthus of the eye to the mandibular axis of the the tragus of the ear condyle Dr. Wafaa Ibrahim Page 2  Anatomic Landmarks 1 Intra oral Anatomical landmarks I- Maxilla A- Border (limiting) structures that limit the periphery of the denture 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 dislodgement of the denture and/or soreness of the area While failure to cover the areas up to the limiting structure decreased retention stability and support. Anatomical structure Description Prosthetic value 1. Labial frenum Fold of mucous Labial notch should be membrane that may be provided in the denture to single or multiple facilitate functional extending from the movement of the frenum and mucous lining of the lip avoid ulceration. towards the crest of the ridge on the labial surface. 2. Labial vestibule Extends on both sides The reflection of the mucous from the labial frenum to membrane superiorly the buccal frenum. determines the height of the denture flange. 3. Buccal frenum Folds or folds of mucous Denture borders should be membrane that vary in functionally trimmed to size and position, and avoid dislodgment of the extends from the buccal denture during function. Dr. Wafaa Ibrahim Page 3  Anatomic Landmarks 1 mucous membrane reflection area to the crest of the residual ridge. 4. Buccal vestibule The space distal to the –Buccinator muscle will not buccal frenum. Bounded displace the denture externally by the cheek (horizontal direction of the and internally by the fibers). residual ridge. –Thickness of the distal end of the buccal flange must accommodate the coronoid process (displace denture). - The size of the buccal vestibule varies with:  contraction of the buccinator muscle  coronoid process of the mandible during opening 5. Hamular notch Notch located between – Posterior palatal border of maxillary tuberosity the denture should extend anteriorly and the from hamular notch on one pterygoid hamulus side to the hamular notch on posteriorly. the other side passing through vibrating line of soft palate. – Its mucous membrane contains thick submucosa with loose areolar connective tissue that help to achieve posterior palatal seal. 6. Vibrating line of the soft palate Soft palate has two parts; – Posterior palatal seal anterior immovable and should be created on the posterior movable. compressible immovable – Vibrating line (Ah tissues of soft palate. line) is an imaginary line –Its width follows soft palate lying between the curvature. movable and immovable parts of the soft palate. – Vibrating line extends from one hamular notch to the other, 2 mm posterior to fovea palatinae following palatal contour. Dr. Wafaa Ibrahim Page 4  Anatomic Landmarks 1 B- Anatomical landmarks of denture bearing area (supporting structures) Load bearing areas Show minimal ridge resorption under constant load. Denture should be designed such that most of the loads concentrated on these areas. Two types of stress bearing areas: primary stress bearing areas secondary stress bearing areas Anatomical structure Description Prosthetic value 1. Alveolar ridge – It is the portion of the alveolar process Later and its soft tissue covering that remains after the extraction of teeth. – The highest continuous surface of the ridge is called the crest of the ridge, it is covered with a layer of dense fibrous connective tissue. 2. Maxillary tuberosity – Distal to the maxillary third molar, the – It is important for denture alveolar process ends in a prominence that retention and support, so it is called the maxillary tuberosity. should be covered. – The size of the maxillary tuberosity is – Extremely large tuberosity affected by the extent of the maxillary may need surgical intervention sinus, which vary in different individuals. before denture construction. Dr. Wafaa Ibrahim Page 5  Anatomic Landmarks 1 3. Palatine vault – Formed anteriorly by hard palate and posteriorly by soft palate. – Palatal surface of the alveolar arch forms the lateral and anterior boundaries of the vault. – It has different forms according to the development of the maxillary processes.(U-V-flat) 4. Median palatine raphe Median palatine suture is covered by a Its position in the palate is thin, dense mucoperiosteum with little or marked with a raised area of no sub-mucosa. mucous membrane called the median palatine raphe, which is relieved to prevent rocking. 5. Incisive papilla A pad of fibrous connective tissue – Located on the palatal side overlying the orifice of the nasopalatine and between the central canal incisors and is used as a guide to place central incisors. – After loss of teeth and excessive bone resorption papilla may require relief to prevent burning sensation. 6. Rugae area Irregularly shaped ridges of connective The rugae are thought to play a tissue covered by mucous membrane in part in speech, especially the anterior third of the hard palate. letter “S” 7. Torus palatinus Raised bony ridge running down the Surgical removal or relief center of the hard palate from the anterior according to size and palatine foramen to the posterior border, extension. any part of this distance. Dr. Wafaa Ibrahim Page 6  Anatomic Landmarks 1 – Small pits or indentations found at the Posterior border of the denture 8. Fovea palatinae midline just posterior to the junction of should extend 2 mm posterior hard and soft palate. to fovea palatinae. – Represent openings of ducts of minor salivary glands. Dr. Wafaa Ibrahim Page 7