Flashcards in Ortho Deck (77):
What is perfect occlusion?
Class 1 molar and incisor relationship, no crowding or spacing, perfect crown angulation/inclination, no rotations, flat occlusal plane
What is normal occlusion?
The normal variation from perfect occlusion
What is malocclusion?
Teeth that dont fit together due to: dent-alveolar factors (crowding/spacing), skeletal pattern (class 1/2.1/2.2/3), soft tissues (lips, cheeks and tongue) and local factors (missing/ectopic/extra teeth)
What are the risks of crowded teeth?
What is the risk of having an overjet?
Tooth damage from trauma
What is a functional appliance?
Corrects class II and jaw alignment, can be either fixed or removable, work by retraining U jaw and increasing growth of L jaw by 1-2 mm
What is a fixed appliance/
Attached to teeth and capable of causing bodily movement of teeth and rotation
What is a removable appliance?
A brace that can be removed from the mouth and tilts single teeth and widens the arches
What is balancing?
When you also extract any tooth on the opposite side fo at the same arch to keep the centre line
What is compensating?
When you also extract the same tooth in the opposite arch ti prevent over-eruption and maintain the molar relationship
How common are submerged teeth?
Which jaw are submerged teeth more common?
What is submergence?
Infraoccluded deciduous teeth when successor is absent (may also shed when successor erupts or occasionally prevents eruption of the successor)
Why is there variation in dentoalveolar factors?
Genetics (60%) and unknown environmental factors (40%)
How common is class 1?
What order do the classifications go in frequency?
1 > 2.1 >2.2 >3
What causes crowding?
Large teeth, small arch, combo of both
Teeth are mesially angulated hence they erupt forward = crowding
How should deciduous teeth look?
Spaced (3 years) to make room for the permanent teeth and close all available teeth (8.5 years)
What is predictive of permanent teeth?
Deciduous teeth at 5 years are:
Crowded = 100%
<3mm spacing = 50%
>6mm spacing = 0%
What is the consequence of early loss of D's and E's?
What dictates where permanent teeth erupt?
(if not enough space for 2s they will erupt palatally unless c's are removed)
How do we treat crowding?
Lateral arch expansion
Antero posterior (headgear)
How do we treat spacing?
Redistributing space (fill prosthetically)
What is are the different class ANB angles?
Class 1 2-4 degrees (3.4 most common)
Class 2 >4 degrees
Class 3 <2 degrees
What is the frankfort plane?
Infraorbital ridge to EAM
What are the signs of an increase lower face height?
Clinically lines meet anterior to back of head
Anterior open bite, reduced overbite and separation of lips
What are the signs of reduced lower face height?
Clinically lines meet posterior to back of head
Prominent chin, increased overbite, lips cover teeth
Define dento-alveolar compensation:
Where the lips and tongue guide erupting teeth into better positions than skeletal class would suggest
n.b. dental bases determine apex location but soft tissues determine crown position
What is the neutral zone?
Where soft tissue continuous forces don't act (oppose each other equally)
How do soft tissues effect stability of treatment?
If teeth are moved into an unstable position (e.g. arches expanded) soft tissues apply pressure making it more likely to relapse.
What is a class 1 incisor relationship?
Ideal overjet and overbite
What is lip competence?
Lips meet together at rest without any muscle activity
What is incompetent but held together?
Lips meet together when mentalis contracts
What is mild incompetence?
<1/2 crown showing
What is marked incompetence?
>1/2 crown showing (this is the only one that matters)
How does lip competence change with age?
Improves (elevates at 9-11 yrs reducing the overjet)
What does lower lip length determine?>
The lip line
What is a normal lower lip length?
at rest it overlaps 3-6mm/ 1/3 of U2 incisal crowns
If lip line unfavourable (low lip line or incompetent lips) what do you do?
2. reduce overjet to <2mm and stabilise occlusion (keep braces on for longer
What does the upper lip length determine?
Amount of upper incisors visible - aesthetics only
Normal 2-3 mm,
'unattractive gummy smile' >2mm
What are the consequences of digit sucking?
Narrow upper arch
What are the consequences from the tongue?
Affects lower arch size
Tongue thrusts (adaptive to incompetent lips to produce anterior seal or endogenous like in downs syndrome or anterior open bite)
What data do you collect for orthodontic diagnosis?
Skeletal pattern - anterio-posterior, vertical, transverse
Soft tissue - lip competency, lip line, upper lip height, tongue, cheeks
Dentoalveolar factors - crowding (mild
What is a class 1 molar relationship?
The U6 mesiobuccal cusp sits in the buccal groove of the L6)
What should a treatment plan include?
1) Malocclusion diagnosis
2) Problem list (recording negative aims i.e. problems that you're going to 'accept'O
3) Plan treatment aims (improve OH, reduce overjet)
4) Plan treat,emt means - i.e. how wet re going to do it ( (OHI, XLA, FA)
Why do we need radiographs in ortho?
- presence of teeth (primary, secondary, missing, ectopic, cysts)
- Position (skeletal class and position of teeth)
- pathology (caries/ bone levels/apical pathology/root resorption/trauma/TMJ disease/cyst)
- pre treatment for diagnosis and treatment planning
- mid treatment for surgical planning, growth changes, treatment progress (indicates stability), root positions, pathology
- post treatment (rare) surgical/ortho relapse and resorption
What can a lat ceph show?
- assess U + L jaws and cranial base (SK class)
- tooth inclinations (occlusal class)
- find ectopic teeth
- implant planning
- monitor growth
- treatment plan and progress
When are lat cephs used?
SK discrepancies using functional/ fixed appliance
What is a class 1 incisor relationship?
The tip of the lower incisor occludes or projects onto the cingulum plateaux of the upper central incisor
How common is a class 1 incisor relationship?
What usually needs to be fixed in a class 1 relationship?
Hyperdontia/hypodontia/macrodontia/microdonti/ectopic canines/transposition etc.
Anterior open bite
Posterior cross bite
What are the causes of an anterior open bite?
Endogenous tongue thrusting
What are the causes of a posterior cross bite>
What is class 2.1 incisor relationship?
The lower incisor tip contacts or projects behind the cingulum plateaux of the upper central incisors (overjet) and the upper centrals are proclaimed or normal
What are the contributing soft tissue factors of a class II incisor relationship?
Low lip line
How does the incisor classification affect trauma risk?>
In a class II relationship the upper incisors are more likely to be traumatised due to the overheat (5mm 22%. 9mm 24%, >9mm 44%)
What are fixed appliances good at?
Multiple bodily movement of upper labial segment
Non aligned arches
What us 2.2 incisor relationship?
The lower incisor tip occludes or project posteriorly to the cingulum plateaux of the upper central incisors and the upper central incisors are retroclined
Which incisor class is growth favourable to?
Class 2 - jaw grows down and out
What is the average growth of a childs mandible?
2mm increase from 11 y/o to end of growth
What is class 3 incisor relationship?
The lower incisor tip occludes or projects anterior to the cingulum plateau of the upper central incisors
When are girls in their peak growth?
When do girls stop growing?
When are boys in their peak growth?
When do boys stop growing?
How do we monitor facial growth?
Monitor height using tanner graphs - parallel to facial growth - we cannot predicts changes in SK only assume average
When does inter canine width stop?
At 10 y/o
When should you treat class 2?
Early (growth is favourable)
when should you treat class 3?
Late (growth unfavourable)
When should orthognathics and implants be done?
Once growth has stopped
How does headgear and functional appliance affect growth?
Restrains Maxilla and enhances growth in mandible (2-3mm)
What is relapse?
The return of malocclusion following correction
What is stability?
teeth in equilibrium with soft tissues
What is retention?
Stabilisation of post treatment occlusion
What are the causes of relapse/factors of stability)
Occlusion - overbite in class 3 = 135 intercuspal angle in class 2.1, intercuspation in all cases
Soft tissues - incompetent lip, teeth out of neutral zone, lips
Growth - worsened lower ant. crowding, forward mandibular rotation = increased overbite, backward mandibular rotation = worsen anterior open bite
Periodontal tissues - new bone more susceptible to remodel (3 months), sharpey fibres reorganise (1-2 months), supracrestal fibres (reorganise >6 months), free gingival fibres (reorganise >12 months)
When do we use a fixed retainer?
When instability is more likely:
Lower incisor crowding
- arch expansion or incisor proclamation (L)