basic lecture about orthodontic management of class III malocclusion

1. ‫الرحيم‬‫الرحمن‬‫هللا‬‫بسم‬
Ibn Sina University
Faculty of Dentistry
Department of Orthodontics
Class III malocclusion
Mohanad Elsherif
BDS (U of K), MFD RCSI, MFDS RCPS(Glasg), MSc (Orthodontics), M.Orth. RCSEd

2. Objectives
 Definition
 Incidence
 Types
 Etiology
 Clinical features
 Diagnosis
 Treatment

3. Definition
 Angle classification.
 Incisor classification.
 Canine classification.

4. Angle definition of class III
It state that: {the mesiobuccal cusp of the upper first permanent
molar occlude posterior to the buccal groove of the lower first
permanent molar}.

5. Incisor’s definition of class
III
It state that: the incisor edges of the lower permanent central
incisors occlude anterior to the cingulum platue of the upper
permanent central incisors. The overjet may be reduced or
reversed.
O
R
O
R

6. Canine definition of class III
It state that: the tip of the upper canine occlude posterior to
the embrasure between lower canine and first premolar.

7. Incidence
 In UK: 3-5 %
Foster & Day, 1974,
Todd and Dodd 1975
 More common in Asian: 4-14%
Lew 1993
 In Africa: 12%
Chukwudi 2003

8. Types
 True class III
These molar and incisors are class III and usually
associated with class III apical base relationship.
 Pseudo class III
Anterior displacement of mandible due to
occlusal prematurity or the molar are class I
while the incisor are class III.

9. Clinical Features
 Skeletal features
 Soft tissue features
 Dental features
 Cephalometric features
 Displacement
 Path of closure

10. Clinical features
 Skeletal features:
 Cranial base:
• Short cranial base length.
• Decrease cranial base angle
resulting in forwards position of
mandible.

11. Clinical features
 Skeletal features:
 Antero-posterior relations:
• Mainly class III due to:
 Retrognathic maxilla
 Prognathic mandible
 Combination.
• Sometimes can be class I or mild class II

12. Clinical features
 Skeletal features:
 Vertical relation:
• 59% has normal or reduced
Lower facial height.
• 41% has an increased lower
facial height.
Guyer 1986

13. Clinical features
 Skeletal features:
 Transverse relation:
• Narrow maxilla and/or wide mandible.
• skeletal asymmetry (specially in the
mandible).

14. Clinical features
 Soft tissue features
 Soft tissue not involved in etiology but
encourage dentoalveolar compensation.
 However some features might be present:
 Obtuse Nasolabial angle
 Reduced incisor show at smile
 Increase buccal corridor dark space
 Obtuse labiomental fold
 Prominent chin
 Concave or straight profile with anterior divergence.
 Increased throat length

15. Clinical features
 Dental features
 Class III incisor relationship
 Mostly CI III molar and canine relationship.
 Tendency to or full reverse Overjet,
 Reduced Overbite or Anterior openbite may exist
 Often crowding in the maxillary arch.
 No crowding in the mandibular arch or even spacing
 Incisors compensate for Skeletal base, i.e. Proclined maxillary
incisors and retroclined mandibular incisors
 Transverse discrepancy expressed in a form of tendency to
posterior cross bite.

16. Clinical features
 Cephalometric features
 Reduced cranial base angle
 Obtuse gonial angle
 Reduced ANB
 Normal or increase MMP angle and lower
face height
 Increased mandibular length
 Reduced maxillary length

17. Clinical features
 Displacement:
 Could be in anterior or lateral direction or combination of
both
 Mostly CI III molar and canine relationship could be I or
even II.
 Growth:
 Usually unfavorable

18. Diagnosis
 History
 Examination
 Diagnostic records
 Growth Assessment

19. Treatment
Class III can be skeletal and/or dental in nature.
 Dental class III can be corrected with
orthodontic treatment alone using fixed or
removable appliances.
 Skeletal class III means that there are problems
with the size and/or the position of the jaws.

20. Treatment Options
 There are three treatment
option for skeletal class III:
 Growth modifications.
 Orthodontic camouflage.
 Orthographic Surgery.

21. Growth Modification Vs Camouflage VS
Surgery
 This will depend on:
 The patient age.
 Medical status.
 The severity of skeletal discrepancy ( mild, moderate
or sever problem?).
 The pattern and direction of future growth.
 The degree of dentoalvelor compensation.
 The patient concerns ( if he/ She desire major facial
changes.

22. Growth modification
 In growing patient class III can be due
to:
 Deficient maxillary growth
 Excessive mandibular growth
 Combination of both

23. Maxillary deficiency
 Both anteroposterior and vertical maxillary
deficiency can contribute to Class III
malocclusion.
 If the maxilla is small or positioned
posteriorly, the effect is direct.
 if it does not grow vertically, there is an
indirect effect on the mandiblewhich then
rotates upward and forward as it grows,
producing an appearance of mandibular
prognathism that may be due more to the
position of the mandible than its size.

24. Maxillary deficiency
 Growth modification for lass III due to
maxillary deficiency can be achieved by:
 Reverse-pull headgear.
 Frankle III functional appliance (???).
 Class III elastics to skeletal anchorage (???).

25. Facemask (reverse-pull headgear)
 Also called protraction headgear or mask of
delaire.
 Cause protraction of the maxilla.
 Used in treatment of skeletal class III due to
maxillary deficiency.
 Force are usually high (400-500 mg/per side).
 The force should be directed 15-20° to the
occlusal plane.
 Should be used before age of 10 years to
produce maximum skeletal effects.

26. Facemask

28. Camouflage for class III
 The decision for camouflage or surgery must be made
before treatment begins because the orthodontic
treatment to prepare for surgery often is just the opposite
of orthodontic treatment for camouflage.
 It is a serious error to attempt camouflage on the theory that if it
fails, the patient can then be referred for surgical correction.
 At that point, another phase of “reverse orthodontics” to
eliminate the effects of the original treatment will be required
before surgery can provide both normal jaw relationships and
normal occlusion.

29. Camouflage for class III
Options for extractions:
 For class III
 Extraction of lower first
premolars only.
 Extraction of upper 2nd
and lower 1st premolars.
 Extraction of one lower
incisor.

30. Declaration
 The author wish to declare that; these presentations are his original work, all
materials and pictures collection, typing and slide design has been done by the
author.
 Most of these materials has been done for undergraduate students, although
postgraduate students may find some useful basic and advanced information.
 The universities title at the front page indicate where the lecture was first
presented. The author was working as a lecturer of orthodontics at Ibn Sina
University, Sudan International University, and as a Master student in Orthodontics at
University of Khartoum.
 The author declare that all materials and photos in these presentations has been
collected from different textbooks, papers and online websites. These pictures are
presented here for education and demonstration purposes only. The author are not
attempting to plagiarize or reproduced unauthorized material, and the intellectual
properties of these photos belong to their original authors.

31. Declaration
 As the authors reviews several textbooks, papers and other references during
preparation of these materials, it was impossible to cite every textbook and journal
article, the main textbooks that has been reviewed during preparation of these
presentations were:
Contemporary Orthodontics 5th edition; Proffit, William R, Henry W. Fields, and
David M. Sarver.
Handbook of Orthodontics. 1st edition; Cobourne, Martyn T, and Andrew T. DiBiase.
Clinical cases in orthodontics. Martyn T. Cobourne, Padhraig S. Fleming, Andrew T.
DiBiase, Sofia Ahmad
Essentials of orthodontics: Diagnosis and Treatment; Robert N. Staley, Neil T. Reske
Orthodontics: Current Principles & Techniques 5th edition; Graber, Lee W, Robert L.
Vanarsdall, and Katherine W. L. Vig
Orthodontics: The Art and Science. 3rd Edition. Bhalajhi, S.I.

32. Declaration
 For the purposes of dissemination and sharing of knowledge, these
lectures were given to several colleagues and students. It were also
uploaded to SlideShare website by the author. Colleagues and students
may download, use, and modify these materials as they see fit for non-
profit purposes. The author retain the copyright of the original work.
 The author wish to thank his family, teachers, colleagues and students
for their love and support throughout his career. I also wish to express
my sincere gratitude to all orthodontic pillars for their tremendous
contribution to our specialty.
 Finally, the author welcome any advices and enquires through his
email address: Mohanad-07@hotmail.com

33. Thank You