Malocclusion Class 1 Flashcards
Class 1 malocclusion
Lower incisor edge lies on cingulum plateau of upper central incisor
Incidence of class 1
60%
Skeletal pattern in class 1
AP RELATIONSHIP?
Full range, mostly average but also increased and reduced face height
Sk1 normal incisors -normal incisors ,
Mild sk class 2 - normal U , L proclined,
Mild sk class 3 - Proclined U , L Retroclined
Dentoalveolar compensation
A mechanism through which soft tissues (lips, tongue, cheeks) produce more class 1 incisor relatiohship when AP skeletal pattern is SK 2 or SK3.
Dento- alveolar compensation for class 3 SK.
- Proclined upper incisors
- Retroclined lower incisors
They tend to go towards class 1
Class 2 Sk Dento Alveolar compensation
- Retroclined upper incisors
- proclined lower incisors
They tend to go towards class 1
Transverse Dimension
Facial asymmetry
- Biological variation - usual situation
- pathological- condylar hyperplasia
Facial asymmetry
I/O
- centre line discrepancies
- Posterior cross bites +- ( mandibular displacements)
If you see one of these go back and check facial asymmetry.
Soft tissues?
-The soft tissues pattern in class 1 is generally favourable and doesn’t change facial growth
Malocclusion class 1
COMMON FEATURE
- Crowding
- Spacing
- Bimaxillary proclination
- local factors
- pathology
- Anterior open bite
- posterior open bite
- local cross bite
- unilateral cross bite
- Bilateral cross bite
Crowding because? And tx
- very common problem
- too much tooth tissue for arch size
- mild crowding, Non XT
- moderate to severe- XT of premolar +-EOT
Spacing why and tx?
- smalll teeth on normal Jaws
- Normal sized teeth on large jaws
- missing teeth
Tx- Close space or redistribute space
Bimaxillary proclination why?
- Upper and lower incisors proclined.
- influenced by soft tissues
factors?
- variation in tooth number - extra teeth supernumeraries or hypodontia
- variation in tooth form- Macrodonts, microdonts,
- Abnormalities in tooth position - can be canine but more likely in Class 2 div 2. transposition ( most transposition involves canine
- local abnormalities of soft tissue : frenum
- local pathology : Cyst
-AOB - Sk cause - due to increase lower face height, Habbit due to digit sucking , Soft tissues due to tongue activity ( seen in Down’s syndrome pt) ( hard to diagnose, usually diagnose of exclusion)
- SK and soft tissue AOB almost always symmetrical , digit effect asymmetrical.
-Habit- Digit habit can produce AOB sometimes,
Posterior cross bite
-Transverse occlusion problem ( one arch is bigger than other) - can occur in any class
-CAUSE OF Posterior cross bite- narrow maxilla i.e- transverse sk discrepency. Digit sucking habit- discuss the reasons, local problem often related to local crowding.
- Crossbites unilateral (May associated with mandibular displacement) always check. Mandibular displacement , bilateral -Bilateral cross bite
Aim and objectives Class 1 Malocclusion
- understand /Aetiology of class 1 malocclusion
- understand problem tha may require tx class 1 mal
- know some key points about tx of class 1 mal