Class III Flashcards
Describe a suitable pt for camouflage tx to fix a class III malocclusion
- Mild-Moderate Skeletal III pattern
- Px happy with facial profile
- Potential to procline upper teeth & retrocline lowers
- Good overbite
- Patient not growing adversely
- Patient can achieve an edge-to-edge incisors
- Minimal pre-treatment dentoalveolar compensation
Clinically (in regards to teeth only) what may you expect to see in a class III malocclusion pt?
- Reduced incisor show at smiling
- Increase buccal corridor dark space
- Upper dentition tends to have more crowding
- Incisors will have compensation for the Skeletal base, i.e. Proclined maxillary and retroclined mandibular incisors
- Potential posterior crossbite (due to transverse discrepencies)
- reverse OJ/ reduced OB or AOB
When are fixed applainces needed when a pt needs orthgnathic surgery?
Fixed appliances required
Before surgery
During surgery
After surgery
What is considered late age treatment when treating class III malocclusion? And what tx can be done at this stage?
Over 16 years - NON-GROWING
Growth modification NO LONGER AN OPTION
Camouflage if possible (facial profile not a concern) or Orthognathic Surgery + Fixed appliance
What teeth are normally extracted for camouflage tx of class III malocclusion?
Fixed appliances usually with the extraction of lower 4s or upper 5s
What are the components of an upper removable appliance?
Remember ARAB
A - active
Z-spring or T-Spring or Screw (more than one tooth)
R- retention
Adam’s Clasps 6s and Ball ended Clasps on Es
A- anchorage
The resistance to unwanted tooth movement
Involvement of more teeth in the appliance than just the anterior teeth
B- baseplate
Posterior bite blocks and midline screw - allows for the bite to be opened and expansion of the upper arch
What are some relavant history questions you would ask a pt with class III malocclusion?
- Px concerns? Facial or dental concerns
- Age: Growing (10-16 years) or non-growing, to determine functional appliance use
- Family history: Genetic skeletal III (does anyone in the family have similar concerns? Has anyone ever had facial surgery?)
- Medical History
- Previous orthodontic work?
- Habits
Why is it important to diagnose potential mandibular prognathism in skeletal class III pts at the start of the treatment?
(increased growth of mandible)
Skeletal III patterns with mandibular prognathism can commonly have an asymmetry, it is important to diagnose this at the start of any treatment as its management will need to be planned accordingly
Label the following features that are common to see in a pt with a class III malocclusion
- Increase scleral show (white part of eye)
- Cheekbone flattening (Malar hypoplasia in midface deficiency)
3.. Paranasal hallowing (either side of nose flattened) - Obtuse Nasio-Labial Angle
- Thin upper lip
- Prominent chin
- Increased throat length
What special investigations would you need to diagnose a class III malocclusion?
OPG
Lateral Ceph
+/- Upper standard occlusal
Define a skeletal III relationship
Forward mandibular position with respect to the cranial base or maxilla
What are the treatment options for class III malocclusion?
- No treatment
- Growth modification
- Camouflage
- Orthgnathic surgery
Why do we treat class III malocclusion?
- Concerns regarding aesthetics
- Psychological well being
- Masticatory problems
- Speech problems
- Concerns regarding dental health - (tooth surface loss, gingival recession)
Define class III molar relationship
The mesiobuccal cusp of the maxillary first molar occludes posterior to the buccal groove of the mandibular first molar
What is considered early treatment when treating class III malocclusion? And what tx can be done at this stage?
Less than 10 years as still growing and has mixed dentition
Growth Modification
(however poor stability, compliance and unpredicatble growth)
Define interceptive treatment
Any treatment which eliminates or reduces the severity of a developing malocclusion in order to eliminate or simplify the need for future treatment (Chung 1987)
Define Class III incisor relatoinship
The lower incisor edge lies anterior to the cingulum plateaux of the upper incisor teeth; overjet may be reduced or reversed
BSI Classifictaion
Describe an ideal patient for interceptive treatment
- Growing - early/late mixed dentition
- Good Oral Hygiene
- Motivated
- Enough teeth to retain an Upper Removable Appliance or a Small fixed appliance (such as a 2x4)
- Good overbite, average or reduced vertical dimensions - allows for the result to be retained
- Traumatic occlusion which can be relieved by correction of the crossbite and elimination of the displacement
- Mild malocclusion - the patient should be able to posture into an edge to edge occlusion.
What are some dental aetiological factors that contribute to a class III malocclusion?
hypodontia/microdontia/impacted in maxillary arch
Narrow upper arch & broad lower arch
What are some skeletal aetiological factors that contribute to a class III malocclusion?
Short or Retrusive Maxilla (Hypoplasia)
Long or Prognathic Mandible (Hyperplasia)
Combination of both
Most pts have a combinatiom of both
Besides dental and skeletal what are some other aetiological factors that contribute to a class III malocclusion?
Genetics (E.g. Hapsburg Royal Family)
Cranio-facial Anomalies (E.g. Cleft lip & palate or Binders Syndrome)
What is considered intermediate age treatment when treating class III malocclusion? And what tx can be donew at this stage?
10-16 years old, adult dentition still growing
Growth modification or camouflage
Why would cleft lip rest in a class III skeletal relationship?
Scarring from the repair of the cleft in the palate can result in less growth of the maxilla
What soft tissue factors can contribute to class III relationship?
*Macroglossia - results in proclination of the lower labial segment
- High Angle cases - where there is a tongue to lower lip adaptive seal that might worsen a class III relationship.
Name the ceph values you’d see in a typical class III pt
Reduced cranial base angle
Obtuse gonial angle
Reduced ANB
Normal or increase MMP angle and lower face height
Increased mandibular length - can be measured as part of the Harvold Analysis
Reduced maxillary length - can be measured as part of the Harvold Analysis
What factors do we consider when planning tx for class III pts?
*Age
*Growing / Non-Growing
*Family history of Class III skeletal pattern - will affect the timing of treatment
*Patients concern - facial or dental
*Severity of skeletal discrepancy
*Amount of dento-alveolar compensation - Upper teeth proclination, Lower teeth retroclination, there are limits beyond which camouflage is not possible
What is the criteria for growth modification tx for class III?
*Ideally <10 years
*Mild to moderate skeletal discrepancy
*Patient able to achieve an edge to edge occlusion
*Average or reduced vertical dimensions
*Motivated patient and parents
*Mainly maxillary hypoplasia
*Average or Retroclined upper incisors and average or proclined lower incisors
Give some examples of growth modification tx options for class III
*Protraction headgear with or without rapid maxillary expansion
*Functional appliances e.g. Frankel III or reversed Twin Block
What does the decision to extract in a class III pt depend on?
The decision to extract depends upon the degree of crowding, the amount of lower incisor retraction required, the amount of upper incisor proclination that can be allowed and the likely future growth.
What do the principles involved in the comprehensive treatment of Class III malocclusions with fixed appliances include?
Relief of crowding
Level and aligning the arches
Increase the overbite and overjet
Correct buccal segment relationships
Plan retention.
Class III intermaxillary elastics can be used to retract the lower incisors using the upper arch as …?
Anchorage
