CLASS 1 MALOCCLUSION

CLASS 1 MALOCCLUSION


Definition:
>>Angle’s class I malocclusion is also known as neutrocclusion where the molars are in normal class I relationship(Mesiobuccal cusp of the upper first permanent molar lies in the mid buccal groove of the lower first permanent molar)
leaving the other teeth in malocclusion.
>>Harmonious relationship of the underlying skeletal structures and malocclusion component is restricted to the dental malrelations only..
Class I malocclusion
Most common forms are:
1) Class I malocclusion.

2) Bimaxillary protrusion

FEATURES OF CLASS 1 MALOCCLUSION
Features of skeletal class I malocclusion:
SKELETAL FEATURES:
Harmonious face
Straight to convex profile
Nothing really abnormal

DENTAL FEATURES
Class I molar relationship

Individual tooth malocclusion with varying degree of severity

Malocclusion may be in vertical and transverse planes.
Lip competence is dependant on degree of anterior proclination



MANAGEMENT OF CLASS1 MALOCCLUSION
Treatment aimed at correcting:
Spacing
Crowding
Crossbite
Openbite (anterior)
Rotations
Deepbite (anterior)
Bimaxillary protrusion

DIAGNOSIS:
History
Clinical examination
Study models
Radiography
OPG
Periapical
Lateral ceph

SPACING

Generalized:
Eliminate cause
Microdontia
Eliminate spaces between anteriors,leaving a space between canine and 1st premolar
Prosthesis
Spacing with proclination:
Labial bow
Elastics with fixed or removable appliance

Localized spacing with proclination:
Labial bow with finger spring
Midline Diastema:
Eliminate cause i.e. high labial frenum attachment
Removable appliances:
Finger spring
Finger spring with labial bow
Split labial bow
Fixed appliances:
Pin and tube appliance.

CROWDING
CROWDING
Analyze space discrepancy using model analysis.
Treatment is planned on the amount of space required.
Mild Crowding:
If the space discrepancy is up to 4mm:
usually resolves without extraction.
Proximal stripping
Alignment of teeth by labial bow, finger spring.




CROWDING
Moderate crowding:
If space discrepancy is in the range of 5-9mm, treated without extractions by :

Arch expansion
Molar anchorage or
Enamel reduction.


CROWDING
Severe crowding :
Patients with space discrepancy of 10 mm or more:
Extract all 1st premolars
Retract canine by canine retractor
Align anteriors by labial bow
Retention by Hawley’s retainer.





HAWLEY’S RETAINER
CROSSBITE
CROSSBITE:it is when upper tooth lie lingual to their opposing lower teeth.its of tow types:Anterior c.bite:involving one or more incisors or canine.it may be associated with anterior mandibular displacement……Posterior c.bite:involving one or more premolar or molar.its of 2 types:a-buccal c.bite:the buccal cusp of the mand. Tooth lies Buccal to the maximum height of the Buccal cusp of apposing max. tooth…..b-scissors bite{lingual c. bite}:the Buccal cusp of the mand.tooth lies lingual to the maximum height of the lingual cusp of opposing max.tooth…..
TREATMENT OF CROSSBITE
ANTERIOR
Z-spring with posterior bite plane
Expansion screw with posterior bite plane

CROSSBITE
POSTERIOR
Single tooth:
Cross-elastics
Unilateral:
Unilateral expansion screw
Functional appliance
Bilateral:
Maxillary expansion is done to relieve cross bite by:
Coffin spring
CROSSBITE
Quad Helix Appliance

CROSSBITE
Hyrax screw for rapid maxillary expansion

OPEN BITE
OPEN BITE
ANTERIOR:
Eliminate habit
Thumb sucking
Tongue thrust
Mouth breathing
Skeletal openbite
during mixed dentition:
Frankel IV or chin cap with high pull headgear
In permanent dentition,before puberty
Fixed appliance with box elastics
In permanent dentition after puberty:
Surgery
If due to supra-erupted posteriors:
Posterior segmental osteotomy

ROTATIONS
ROTATIONS
Single Tooth:
Removable Appliance:
Couple force by flapper spring/ double cantilever spring and labial bow
Semi-fixed Appliance:
Whip spring
High labial bow with soldered ‘T’ spring
Multiple rotations:
Treated by fixed appliance
Overcorrection is done and retention is given for atleast 1 year….
ROTATIONS
High Labial bow




T spring


DEEP BITE
DEEP BITE
Growing age:
With less low facial height:
Anterior bite planes
DEEP BITE
Anterior bite planes are contraindicated if patient already has more lower facial height.
Intrude anteriors by:
Fixed appliance
J hooks of vertical pull headgear

BIMAXILLARY PROTRUSION
A bimaxillary protrusion is a condition in which the maxillary and the mandibular incisor teeth protrude severely so that the lips cannot be closed together. Because not all bimaxilary protrusion patients are candidates for surgical correction, patient assessment and selection remain main issues in diagnosis and treatment planning. The purpose of this study was to separate bimaxilary protrusion patients who can be properly treated orthodontically from those who require orthognathic surgery. 
FEATURES OF BIMAXILARY PROTRUSION
SKELETAL FEATURES:
Prognathic jaws
Increased ANB angle
Convex profile
Everted lips
Smaller upper and posterior facial height with divergent facial planes


DENTAL FEATURES:
Bimaxillary proclination
Increased incisal angle
Spacing between teeth
Normal molar and canine relationship
Steep mandibular plane angles


TREATMENT OF B.M.P
TREATMENT OFBIMAXILLARY PROTRUSION
Extract all 1st premolars, or 1st molars.

Treatment depends on angulation of canine:

Distally inclined canine:
Retract canine and align incisors using retainers
Mesially inclined canine:
Fixed appliance
Treatment of BIMAXILLARY PROTRUSION
Use of anterior subapical osteotomy in conjunction with extraction of a tooth in each quadrant, usually the 1st premolars.
Bone apical to upper 6 anteriors is cut, and the whole segment is pushed back, in conjunction with surgical splints and rigid osteosynthesis (plating).
Box and vertical elastics and retainers are used postsurgically to prevent relapse of teeth.
Pre and post treatment lateral view
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REFERENCES
Lecture notes
Contemporary orthodontics by William R Proffit
www.wikipedia.org
www.Library.thinkquest.org