5_6174796343119184192.pdf - lec 7 Orthodontics Points and...

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د . دورو اللهريخ lec. 7 Orthodontics 1 | P a g e Points and landmarks-described in the lateral projection Unilateral landmarks Sella(S) : The center of the hypophyseal fossa (pituitary gland fossa) (sella turcica). It is selected by the eye, since that procedure has been shown to be as reliable as a constructed center. Nasion (NA): The most anterior and superior point on the frontonasal suture on the curve at the bridge of the nose. Anterior Nasal Spine (ANS) : The most anterior point on the maxilla at the level of the palate. Posterior Nasal Spine (PNS) : The most posterior point on the bony hard plate in the sagittal plane: usually the meeting point of the inferior and superior surfaces of the hard plate. Subspinale ("A" Point) : The most posterior point on the curve between ANS and PR (SPr). "A" point is usually found 2mm anterior to the apices of the maxillary central incisor root. Superior Prosthion (SPr or PR) : Also termed s upradentale . The most anterior inferior point on the maxillary alveolar process, usually found near the cemento- enamel junction of the maxillary central incisor. Incision Superius (Is) : The incisal tip of the most anterior maxillary central incisor. Incision Inferius (Ii) : The incisal tip of the most labial mandibular central incisor. Infradentale (Id) : Also termed inferior prosthion . The most anterosuperior point on the mandibular alveolar process usually found near the cemento- enamel junction of the mandibular central incisor. Supramentale ("B" point) : The most posterior point of the bony curvature of the mandible below infradentale and above Pogonion. "B" point is usually found near the apical third of the roots of the mandibular incisors and may be obscured during the eruption of these teeth. When the profile of the chin is not concave, "B" point cannot be determined. Pogonion (Pog) : is the most anterior point on the contour of the chin. Pogonion usually is located by a tangent perpendicular to the mandibular line or a tangent dropped to the chin from Nasion. Menton (Me ) : is the lowest point on the symphyseal outline of the chin.
د . دورو اللهريخ lec. 7 Orthodontics 2 | P a g e Gnathion (Gn) : The most anteroinferior point on the lateral shadow of the chin. Gnathion may be approximated by the midpoint between pogonion and menton on the contour of the chin. Basion (Ba): The most inferior point in the sagittal plane on the anterior rim of the foramen magnum-the tip of the posterior cranial base. Bilateral landmarks Orbitale (Or): the lowest point of the bony orbit. In the PA cephalogram, each may be identified but in the lateral cephalogram the outlines of the orbital rims overlap. Usually, the lowest point on the average outline is used to construct the Frankfort plane.

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