Lecture notes Orthodontics - TERMINOLOGY, CLASSIFICATION, HISTORY AND EXAM

TERMINOLOGY, CLASSIFICATION, HISTORY AND EXAM
●​ Orthodontics = branch of dentistry concerned with alignment and development of teeth and jaws

Extra-oral exam
●​ Skeletal relationship
o​ AP skeletal relations (anteroposterior - maxilla and mandible in relation to each other) – zero meridian
line and Frankfort Plane
▪​ 2 methods to classify skeletal pattern - palpation/bi-manual palpation OR zero meridian
methods
●​ I = normal relationship between maxilla and mandible
●​ II = mandible relatively retrusive (behind maxilla)
●​ III = mandible relatively protrusive (in front of maxilla)
▪​ Bi-manual palpation technique:
●​ Index finger on cupids bow, middle finger on concavity of mandible - assess change in
inclination




●​ Zero-meridian method:
○​ Relies on Frankfort plane (horizontal) and zero meridian line (ZML) (vertical)




●​ Skeletal 1 - Chin on or up to 2mm behind the ZML
●​ Skeletal 2 – Chin behind the ZML
●​ Skeletal 3 – Chin in front of the ZML
o​ Vertical relationship - FMPA = Frankfort mandibular plane angle; LAFH = Lower anterior face height
▪​ LAFH: Glabella (mid-eyebrow) → Subnasale → soft tissue gnathion (low part of chin)
▪​ Facial thirds: male 72mm, female 66mm