Cephalometric

Lecture two

Cephalometric assessment

Cephalometric lines of reference

1. True horizontal:
Can be identified when the patient’s head is in the natural postural position, this line is differ from one person to other.

Cephalometric lines of reference

Cephalometric lines of reference
2. Frankfort plane:
Po - Or

Cephalometric lines of reference

3. Sella - Nasion plane:
S - N

Cephalometric lines of reference

4. De Coster’s line:
The floor of the anterior
cranial base, from ethmoid
bone to sella turcica





Cephalometric lines of reference
5. Maxillary line:
ANS - PNS

Cephalometric lines of reference

6. Mandibular plane:
Me - Go

Cephalometric lines of reference

7. Occlusal plane:
Cusp tips of molars – tip of lower incisor





Cephalometric lines of reference
8. Functional occlusal plane (FOP):
Cusp tip of lower 1st molar –
cusp tip of lower 1st premolar

Cephalometric lines of reference

9. The facial plane:
N - Pog

Cephalometric lines of reference

10. Line from point A to pogonion:
A - Pog

Antero-posterior skeletal relations

Antero-posterior skeletal relations
SNA angle (82 + 3)
Indicates antero-posterior position of maxillary apical base in relation to the cranial base: Large angle = Prognathic maxilla
Normal angle = Orthognathic maxilla Small angle = Retrognathic maxilla

82

Antero-posterior skeletal relations

SNB angle (79 + 3)
Indicates antero-posterior position of mandibular apical base in relation to the cranial base
Large angle = Prognathic mandible
Normal angle = Orthognathic mandible
Small angle = Retrognathic mandible

80

Antero-posterior skeletal relations

ANB angle (3 + 1)
Indicates the skeletal relationship between maxilla and mandible:
Large angle = postnormal relation (skeletal class II)
Normal angle = Normal relation
(skeletal class I)
Small angle (reverse) = Prenormal relation (skeletal calss III)


Antero-posterior skeletal relations
A-B / FOP angle (90 + 5):
Indicates the skeletal relationship between maxilla and mandible with reference to FOP :
Large angle = postnormal relation (skeletal class II)
Normal angle = Normal relation
(skeletal class I)
Small angle = Prenormal relation
(skeletal calss III)

-1 mm

BO anterior to AO
Skeletal AssessmentWits (AO-BO)

Antero-posterior skeletal relations

(wits= University of Witwatersrand)


Facial angle
87° + 3
Indicate the anteropost
Position of the chin

Antero-posterior skeletal relations

N-S-Gn (Y-Axis) = 66⁰
This angle determine the position of the mandible relative to the cranial base



N
S
Gn

Antero-posterior skeletal relations

Vertical skeletal relations

Vertical skeletal relations

MM angle (27 + 5)

Large angle = Skeletal open bite

Normal angle = Normal
Small angle = Skeletal deep bite

Vertical skeletal relations

Frankfort-mandibular angle (27 + 5)

Large angle = Skeletal open bite

Normal angle = Normal
Small angle = Skeletal deep bite

Vertical skeletal relations

Frankfort-SN angle (6 + 5)





32
Vertical Skeletal Assessment

Skeletal Vertical AssessmentNS(SN plane)-GoGn

Dentoskeletal relations
UI / Mx plane angle (108 + 5)

LI / Mn plane angle (90 + 3)

Interincisal angle (133 + 10)

LI / A-Pog distance (0 + 2 mm)

UI / Mx plane angle (108 + 5)

Dental Assessment
108

90

Incisor Angulation Assessment

Dental AssessmentL1-GoGn (Man 1 - GoGn)

0 mm ± 2

Dental AssessmentAPog - Man 1

130

Inter-Incisor Angulation Assessment

Dental AssessmentU1-L1 (Max 1 - Man 1)