Rules in orthodontic practice Mohammed Al Muzian Part 2. Episode 77. February 17th 2021

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Hosted by
Farooq Ahmed

Join me for part 2 where we explore Mohammed’s rules on which teeth to extract, anchorage assessment and management, Bonding 2nd permanent molars, elastics and treatment planning adults Vs children

Which to extract 4 or 5

o   CAT-V principle

§  C: Clinical condition of the teeth

§  A: Anterior crowding: 8mm + extract the 4s, 8mm – 5s or 4s

§  T: Transverse: Lower 5 will help narrow the arch

§  V: Vertical: Extraction of 5s for high angle cases will improve the overbite


Molar outcomes in treatment planning

o   Non-extraction or extraction of 4 premolars = class 1

o   Extraction of 2 upper premolars: Class 2

o   Extraction of 2 lower premolars: Class 3

o   Extraction of 1st molars: Ignore them! Will not change the final molar relationship



o   Type A  (absolute) No movement of the posterior segment

o   TADs – HG – extraction pattern

o   Type B posterior movement moves mesially by 25%

o   Nance, sectional archwires, intermaxillary elastics, HG

o   Type C posterior movement moves mesially by 50%

o   Reciprocal movement of anterior retraction

o   Type D posterior movement moves mesially by 75%

o   Anterior anchorage (reverse HG, TADS)

o   Biomechanics: intermaxillary elastics – 2nd order bends – inverted lower brackets

Anchorage loss in the lower arch is less than upper arch

·      Differential alveolar bone density

·      differential root surface area

·      differential Buccolingual width of molar

·      differential anterior palatal root torques


Bonding upper 7s

o   Don’t bond to for anchorage

o   Bonding results in loss of anchorage due to 7s distally tipped, uprighting results in loss of anchorage


o   Elastics =  rotation of mandible

o   Overjet 0.5mm correction per month with class 2 elastics

o   1:3 ratio of vertical: horizontal effects

o   Unilateral intermaxillary elastics in one side only =  cant

o   = Use vertical part time elastics on the other side

o   Elastic should be stretched 3 times its diameter to give the force

Distalisation Rule

o   Don’t expect you can distalize more than 2.5 mm unless you extract 7 OR 8

o   Distalization lowers without TADS is very limited


Adults Vs growing patients

·      Growing patient:

o   Elastics +++

o   Distalisation +++

o   Functional appliances +++

o   Extractions +++

·      Adult

o   Extractions +++

o   Elastics ++


o   Distalisation +



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