Landmark Definitions

Number  Code        Definition

 1      ME        MENTON - The most inferior point on the symphyseal

                outline.

 2      GN        GNATHION - The most anterior-interior point on the

                contour of the bony chin symphysis. Determined by

                bisecting the angle formed by the mandibular plane

                and a line through Pogonion and Nasion.

 3      PG        POGONION - The most anterior point on the contour of

                the bony chin. Determined by a tangent through

                Nasion.

 4      B        B POINT - The point most posterior to a line from

                Infradentale to Pogonion on the anterior surface of

                the symphyseal outline of the mandible. B Point

                should lie within the apical third of the incisor

                roots. When there is no curvature in this region

                and determination of B Point is not possible by

                the above method, it is chosen with the aid of

                preceding or succeeding films because erupting teeth

                obscure mandibular concavity on occasion.

 5      ID        INFRADENTALE - The anterior superior point on the

                mandible at its labial contact with the mandibular

                central incisor.

 6      LIE        LOWER INCISOR INCISAL EDGE - The incisal tip of

                the mandibular central incisor.

 7      UIE        UPPER INCISOR INCISAL EDGE - The incisal tip of

                the maxillary central incisor.

 8      SD        SUPRADENTALE - The most anterior inferior point

                on the maxilla at its labial contact with the

                maxillary central incisor.

 9      A        A POINT - The most posterior point on the curve of

                the maxilla between the anterior nasal spine and

                supradentale.

10      ANS        ANTERIOR NASAL SPINE - The tip of the median, sharp

                bony process of the maxilla at the lower margin of

                the anterior nasal opening.

11      L        L POINT - Represents a point on the anterior surface

                on the image of the labial lam&la at the apex

                region of the maxillary central incisor. When the

                permanent incisors (before eruption) are positioned

                within bone with there crown in the apical base

                region, L Point is taken 1-2 millimeters anterior

                to the height of contour of the crown relative to

                and on a line drawn through supradentale and parallel

                to the axis of the central incisor. When the permanent

incisors are erupted and their roots are not

                fully formed, L Point is located at the root end

                along an axially placed line through supradentale.

                When the root is completed, L Point is located

                along the same axial line at the root tip. The

                procedure for locating L Point is well illustrated

                by van der Linden, Amer. J. Orthodont., 59:111-125,

                1971.   

12      UIA        UPPER INCISOR APEX - The root tip of the maxillary

                central incisor. In cases where the root is not

yet completed, the midpoint of the growing root

                tip is marked.

13      UIB        UPPER INCISOR LINGUAL BONY CONTACT POINT - The

                lingual contact of alveolar bone with the maxillary

                central incisor. This point generally corresponds

                with the lingual cemento enamel junction (CEJ).

14      LIB        LOWER INCISOR LINGUAL BONY CONTACT POINT - The

                lingual contact of alveolar bone with the mandibular

                central incisor. Generally corresponds with the

                lingual CEJ.

15      LIA        LOWER INCISOR APEX - The root tip of the mandibular

                central incisor. When the root is not yet completed,

                the midpoint of the growing root tip is marked.

16      SYMP        LINGUAL SYMPHYSEAL POINT - A constructed point used

                to determine symphyseal width at Pogonion. The

                SYMP Point is located at the intersection of a

                construction line through Pogonion and parallel

                with the mandibular plane with the posterior border

                of the mandibular symphysis.

17      LMJ        LOWER MOLAR MESIAL CEJ - The anterior cemento-enamel

                junction of the mandibular first molar.

18      LMT        LOWER MOLAR MESIAL CUSP TIP - The anterior cusp

                tip of the mandibular first molar.

19      UMT        UPPER MOLAR MESIAL CUSP TIP - The anterior cusp

                tip of the maxillary first molar.

20      UMJ        UPPER MOLAR MESIAL CEJ - The anterior cement-

                enamel junction of the maxillary first molar.

21      UDJ        UPPER MOLAR DISTAL CEJ - The posterior cemento-

                enamel junction of the maxillary first molar.

22      UDC        UPPER MOLAR DISTAL CONTACT POINT - The posterior

                contact (height of contour) of the maxillary first

                molar.

23      UDT        UPPER MOLAR DISTAL CUSP TIP - The posterior cusp

                tip of the maxillary first molar.

24      LDT        LOWER MOLAR DISTAL CUSP TIP - The posterior cusp

                tip of the mandibular first molar.

25      LDC        LOWER MOLAR DISTAL CONTACT POINT - The posterior

                contact point of the mandibular first molar.

26      LDJ        LOWER MOLAR DISTAL CEJ - The posterior temento-

                enamel junction of the mandibular first molar.

27      GO        GONION - The midpoint of the angle of the mandible.

                Found by bisecting the angle formed by the mandibular

                plane and a plane through Articulare, Posterior and

                along the portion of the mandibular ramus inferior

                to it.

28      GOI        GONIAL INTERSECTION - the intersection of the mandi-

                bular plane with a plane through Articulare, Poster-

                ior and along the portion of the mandibular ramus

                inferior to it.

29      OP        OPISTHION - The posterior midsagittal point on the

                posterior margin of foramen magnum.

30      BA        BASION - The most inferior, posterior point on the

                anterior margin of foramen magnum.

31      AR        ARTICULARE (Articulare Posterior) - The Point of

                intersection of the inferior cranial base surface

                and the averaged posterior surfaces of the mandibular

                condyles.

32      AA        ARTICULARE, ANTERIOR - The point of intersection of

                the inferior surface of the cranial base and the

                averaged anterior surfaces of the mandibular

                condyles.

33      CO        CONDYLION - The most posterior superior point on

                the curvature of the average of the right and left

                outlines of the condylar head. Determined as the

                point of tangency to a perpendicular construction

                line to the anterior and posterior borders of the

                condylar head.. The CO point is, therefore located

                as the most superior axial point of the condylar

                head rather than as the most  superior point on

                the condyle.

34      SOS        CENTER OF THE SPHENO-OCCIPITAL SYNC HONDROSIS -

                The midpoint of the cartilaginous union of the

                anterior end of the basilar  portion of the occipital

                bone and the posterior surface of the body of the

                sphenoid bone. In cases where the synchondrosis is

                not readily apparent, it is located by comparison

                with either previous or subsequent cephalograrns.

35      S        SELLA TURCICA - The center of the pituitary fossa

                of the sphenoid bone. Determined by inspection.

36      SE        ETHMOID REGISTRATION POINT - Intersection of the

                sphenoidal plane with the averaged greater sphenoid

                wing.

37      GB        GLABELLA - The height of curvature of the bone

                overlying the frontal sinus. In cases where this

                point is not readily apparent, the overlying soft

                tissue is used to locate it.

38      N        NASION - The- junction of the frontonasal suture

                at the most posterior point on the curve at the

                bridge of the nose.

39      FMN        FRONTOMAXILLARY NASAL SUTURE - The junction of

                the frontal, maxillary and nasal bones.

40      OR        ORBITALE - The lowest point on the average of the

                right and left borders of the bony orbit.

41      IZ        INFERIOR ZYGOMA - The lowest point on the average

                of the right and left outlines of the zygoma.

42      PTMS        PTFRYGO-MAXILLARY FISSURE, SUPERIOR - The most

                superior point on the average of the right and

                left outlines-of the pterygo-maxillary fissure.

43      PTM        PTERYGO-MAXILLARY FISSURE, INFERIOR - The most

                inferior point on the average of the right and

                left outlines of the pterygo-maxillary fissure.

44      CP        CORONOID PROCESS - The most superior point on the

                average of the right and left outlines of the

                coronoid process. Determined as the point of

                tangency to a perpendicular drawn to the plane of

                the anterior border of the ramus.

45      PNS        POSTERIOR NASAL SPINE - The most.posterior point

                at the sagittal plane on the bony hard palate.

46      PMC        PREMOLAR MESIAL CONTACT POINT - A point established

                by the intersection of a line alond the occlusal

                contact of the upper and lower premolars and a

                perpendicular line to it through the averaged

                anterior contact of the first maxillary premolars

                with the maxillary cuspid.

47      PDC        PREMOLAR DISTAL CONTACT POINT - Established along

                the same premolar occlusion line as point 46 but

                at the point of a perpendicular line through the

                distal contact of the maxillary first premolar.

                The distance from PMC to PCD should be equal to

                the averaged mesial-distal distance of the first

                maxillary premolar.

48      TP        TRICHOTOMOUS POINT - This point has three determin-

                ative methods and interpretations: (a) when the

                permanent first molars are absent (not in occlusion)

                and the deciduous second molars are traced, point

                48 is chosen along a line through points 46 and

                47 and in the region of the anterior border of the

                mandibular ramus. Its presence in this case is to

                indicate that deciduous, rather than permanent

                teeth were traced; (b) when the first permanent

                molars are erupted and traced, point 48 is not

                marked except as below; (c) when the second

                permanent molars are erupted and in full occlusion,

                point 48 is marked at their distal contact points.

49      P0        PORION - The midpoint of the line connecting the

                most superior point of the radiopacity generated

                by each of the two ear rods of the cephalostat.

50      FPP        FUNCTIONAL OCCLUSAL PLANE POINT - This point is

                logically determined and is therefore not a traced

                landmark. It is used to define the posterior loca-

                tion of the functionnal occlusal plane and consequent-

                ly its value is related to the presence (or absence)

                of Landmark 48. (a) If landmark 48 is present and

                the individual is less than 9 years of age, landmark

                50 takes on the same value as landmark 48. (b) In

                all other cases, landmark 50 takes on the value of

                landmark 23.

51      PB        POSTERIOR BORDER OF THE RAMUS - This is defined as

                the intersection of the FOP with the posterior bor-

                der of the mandibular ramus.

52      AB        ANTERIOR BORDER OF THE RAMUS - This is defined as

                the intersection of the FOP with the anterior border

                of the ramus.

53      LT        LINGUAL TUBEROSITY - The Lingual Tuberosity is derived

                by extending the distance between landmarks 51 and

                52 anteriorly along the FOP from the intersection of

                the FOP and the RA Vertical Line.

54      LMC        LOWER MOLAR MESIAL CONTACT - The mesial contact

                (height of contour) of the mandibular first molar

                relative to the FOP.

65      UMC        UPPER MOLAR MESIAL CONTACT - The mesial contact

                (height of contour) of the maxillary first molar

                relative to the FOP.

56      ADP        ANTERIOR DOWNS POINT - The midpoint of the line

                connecting landmarks 6 and 7 (LIE and UID). This

                represents the anterior point through which Downs

                Occlusal Plane passes.

57      PDP        POSTERIOR DOWNS POINT - The midpoint of the line

                connecting landmarks 18 and 19 (LMT and UMT). This

                represents the posterior point through which Downs

                Occlusal Plane passes.