Cephs Flashcards
Cephalostat definition
device used to standardise head position and magnification – to enable comparison.
Standardised how??
- by placing ear posts in external auditory meatus and Frankfort plane parallel to the floor.
- patient must bite together in undisplaced centric position
- magnification: 5%-12%
- x ray tube to head- 150-180 cm (patient in positioned 1.5/ 1.8 m from the xray tube )
- head to film – 30 cm. ( and 30 cm from the film)
Why do we take cephs?
To supplement the clinical examination and asses:
Skeletal pattern
Incisors proclination/retroclination
Soft tissue.
- to determine if patient needs orthognathic surgery or we can camouflage it with orthodontic treatment.
A/P angles + Mean values:
- AnteriorPosterior:
- SNA 81 (3)
- SNB 78 (3)
- ANB 3 (2)
ANB : <2 CLIII, 2-4 CLI, >4 CLII ( skeletal pattern)
= An increase or decrease angle – due to protrusion of retrusion of mandible and maxilla.
Vertical angles + mean values
- MMPA 27 (4)
- FMPA 28 (4)
- LAFH 55% (2)
Incisors relationship angles + mean value
- UinMX 109 (6)
- LinMD 93 (6)
- II 135 (10)
What does incisors angles measure?
Inclination :
- Normal II angle is an important factor in preventing the relapse of deep bite correction.
- The measured inclination of the lower incisors is not only influenced by the inclination of the incisors but also by the inclination of the mandibular plane
Soft tissue angles/ lines:
- Nasiolabial angle
- Lip position to Rickets E-line – lower lip should lie 2mm ( +-2 ) anterior to this line with the upper lip positioned posterior to this line
- A -Pog to lower incisor
- Holdaway line – chin to the upper lip ( extended should bisect the nose)
- Facial plane – line between the soft tissue nasion and chin
Ballard conversion
uses the incisors as indicators of the relative position of the maxilla and mandible
Wits analysis:
compares the relationship of the maxilla with the mandible with the occlusal plane.
