Class III malocclusion, characterized by the lower jaw protruding ahead of the upper jaw, is prevalent among various ethnic groups, with rates ranging from 1% to 8%. Its etiology includes genetic and environmental factors, as well as conditions like cleft lip and palate, presenting with specific clinical features. Diagnosis involves history, clinical examination, and records, with treatment options like face masks and chin cups to redirect jaw growth.

1. CLASS III
MALOCCLUSION

2. DEFINITION
 “ It is defined as the anterioposterior jaw relation in which lower jaw is ahead
of upper jaw with dental features of lower molar more mesially positioned
relative to upper molar”
 Class 3 malocclusion, called prognathism or underbite, occurs when the lower
jaw protrudes or juts forward, causing the lower jaw and teeth to overlap the
upper jaw and teeth.
 Skeletofacial deformity characterized by forward mandibular position with
respect to cranial base and maxilla

4. PREVALENCE
1. Caucasian 1-4%
2. African /American 5-8%
3. Asian
 Japanese 4% younger /14% older
 Indians 1.3%
 Chinese 3% younger /13% older

5. ETIOLOGY
 Skeletal pattern :
Genetic / environmental
•Dental factors
•Familial ( Hapsburg jaw)
 •Environmental ( mouth breathing, postural habits)
•Cleft lip and palate
 Mental disease
 Premature loss of deciduous molars
•Ethnic

6. CLINICAL FEATURES
 Extra oral
1)Concave profile2. Retrusive nasomaxillary area 3)prominent lower third of
face 4)protruded lips 5)steep mandibular plane angle
 Intra oral
1)Narrow upper arch 2) broad lower arch 3)reverse OJ 4)protruded UI
5) Retruded LI

7. DIAGNOSIS
 History
 Clinical examination
 Diagnostic record
1. Cast
2. photograph
3. Ceph

9. FACE MASK
 FACE MASK > Used in patients with mild tomoderate Class III with
maxillaryretrusion > 2 pads connecting soft tissue inforehead and chin region
 2 pads connecting soft tissues in forehead and chin region with a
metallicframework - Elastics attached near the maxillary canine region with a
downward andforward pull of 30° to the occlusal plane - Metallic banded or acrylic
bonded palatalexpansion plate can be attached

10. CHIN CUP

11.  Effects on growth:
 A) Mandible- Redirection of mandibular growth vertically- Backward repositioning
or rotation- Remodeling with closure of gonial angle- Posterior movement of Point
B and Pogonion
 A study by Graber showed that the use of a chincup promoted a backward
movement of Point B, due to a clockwise rotation of themandible. (AJO 1977)B)
Maxilla- Prevents retardation of Anteroposterior maxillary growth
 Types
1. Occipital pull-
2. Vertical pull

12. TANDEM APPLIANCE
 TANDEM APPLIANCE>
 By Chun et al, 1999• Appliance design: (By Leon Klempner, JCO 2011) - Intraoral
appliance with one fixed and tworemovable components - Upper section is fixed
Hyrax, Hass or Quad helix with buccal arms soldered forattachment of protraction
elastics - Lower similar to removable retainer, with posterior occlusal cover- age
and buccal headaear tubes embedded in the lower

13. ORTHODONTIC CAMOUFLAGE
 Depending on the malocclusion extraction can be doneas follows:• Two lower
premolars or a mandibular incisor> All four premolars> Maxillary 2nd and
mandibular 1st premolars> Mandibular second molars[By Jiuxiang Lin, Angle
Orthodontist 2006;76(2)]

14. MANDIBULAR PTOGNATHISM

15. CLASS 3 WITH ANT OPEN BITE