Ortho Flashcards
99% of people have normal occlusion
True or false
False 30-40%
What do you need to tell patients who have an increased overjet who opt not to have ortho
Increased risk of trauma
What are the main issues with impacted teeth (non third molar)
- Cause root root resorption of adjacent teeth
- Cysts associated with them may also cause resorption
- May prevent eruption of adjacent teeth (supernumerary)
What Angle Classification is this:
Mesiobuccal cusp of the upper 6, occludes with the mesiobuccal groove of the lower 6
Class I
What Angles Classification is this?
Mesiobuccal cusp of the upper 6 occludes mesial to the mesiobuccal groove of the lower 6
Class II
What Angles classification is this?
Mesiobuccal cusp of the upper 6 occludes distal to the mesiobuccal groove of the lower 6
Class III
What BSI classification is this?
Lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper centrals
Class I
What BSI classification is this?
Lower incisor edges lie posterior to the cingulum plateau of the upper incisors. Upper 1s are proclined or of an average inclination. Increased overjet.
Class II, Div I
What BSI classification is this?
Lower incisor edges lie posterior to the cingulum plateau of the upper incisors. Upper 1s are retroclined. Usually minimal overjet or may be increased.
Class II, Div II
What BSI classification is this?
Lower incisor edges lie anterior to the cingulum plateau of the upper incisors. Reduced or revered overjet.
Class III
What canine classification is this?
Maxillary permanent canine occludes directly in the embrasure between the mandibular permanent canine and first premolar
Class I
What canine classification is this?
Maxillary permanent canine occludes mesial to the embrasure between the mandibular permanent canine and first premolar
Class II canine
What canine classificaiton is this?
Maxillary permanent canine occludes distal to the embrasure between mandibular permanent canine and first premolar
Class III
Describe a Class I skeletal pattern
Mandible is 2-3mm posterior to the maxilla
describe a class II skeletal pattern
Mandible is retruded relative to maxilla
Describe a class III skeletal pattern
Mandible is protruded relative to the maxilla
Three commonly used indexs for quantitative measure of impacts of malocclusion
- IOTN
- PAR
- ICON
Ideally individuals should have routine oral screening by a GDP from what age
9-10
What is the key indicator for lip incompetency
Muscle contraction visible when patient asked to close lips together.
what is the line from the soft tissue chin to the tip of the nose called?
Ricketts Esthetic Plane or E-line
In an ideal situation, the lower lip is how far form the Rickets E line?
How far is the upper lip?
Lower lip 0 to 2mm posterior to line
Upper lip, slightly further posteriorly
What is assessment of Rickets E plane useful for?
Detecting excessive incisor protrusion
What is the angle of the mandibular plane called
Frankfort mandibular plane angle (FMPA)
Smile lines are usualy 1-2mm higher in females
True or false
True
In an ideal smie, the whoe height of the upper incisor is visible, with only interproximal papillae visible.
true or false
true
What is a consonant smile arc?
Where the upper incisor edges are parallel to the lower lip
In addition to 8s and upper 2s, what other teeth are often congenitally missing
5s
What teeth are most likely to erupt ectopically
6s and upper 3s
What should you do to quantify the space required in each arch for correction of a malocclusion
Space analysis
Space is required in order to correct (6)
- Crowding
- Obtain a normal overjet
- Level occlusal curves
- Arch contraction
- Upper incisor tip
- Upper incisor torque
Mild crowding is less thanmm space needed
4
Moderate crowding is there there is mm space needed
4-8mm
Severe crowding is where there is greater than mm space needed.
8mm
What teeth do you measure in permanent tooth space analysis
Mesial 6 to mesial 6
Spontaneous correction of mild crowding is possible at what age
7-9
Extractons are always required for correction of moderate crowding
True or false
False. Often can treat non-extraction with fixed appliances
As a general rule it is better to leave any ortho extractions until:
Early permanent dentition
At what age do kids usually have a full set of permanent teeth?
12 or 13
For every minimeter of incisor retraction, how much space is needed?
-2mm
For every millimeter of incisor proclination how much space is needed in arch
+2mm
The antero-posterior occlusal curve is called:
Curve of spee
Space is needed to level a curve of spee
True or false
True
List 6 methods of space creation/use
- Extraction
- Molar distal change
- Molar mesial change
- Expansion
- tooth reduction/enlargement
- Space opening
How are molars able to be distalised to create space
- Headgear or fixed intra-oral appliacnes
- Best done before 7s erupt
- Best for upper 6s
What is molar mesialisation for space creation?
Use a space maintainer to maintain leeway space.
How much leeway space in maxilla
0.9-1.5mm per side
How much leeway space in the mandible
1.7-2.5mm (per side)
Up to ……mm can be removed from the mesial and distal aspect of teeth to create space
0.25mm
Effect of early loss of A primary tooth:
Little effect on dentition
Effect of early loss of Bs on the dentition:
Little effect
Effect of early loss of C’s on dentition:
Affect centrelines, not buccal segments
Effect of early loss of D’s on the dentition
Can affect midline AND buccal segments
Effects of early loss of Es on dentition
Affect buccal segments, but not midlines
What is the ideal arch form?
Parabola
It is important to try and conserve the basic arch form of the patient.
True or false
True, particularly lower arch
What is Bolton Analysis used to measure?
Tooth size discrepancy
A TSD below mm is clinically insignificant
1.5mm
4 ways to address tooth size discrpancy:
- Extraction in arch with excess
- interproximal stripping
- Angle teeth to occupy smaller or larger space
- Increase width with resin etc
TSD is intra-arch analysis
True or false
FALSE. it is inter-arch analysis
Space analysis is intra-arch.
From tooth 3-3 a proportional TSD is:
77.2% +/- -.22
(if greater than 77.2% = mn excess, is less, max excess)
What is the % used for bolton analysis of all teeth(as opposed to just 3-3)
91.3% +/- 0.26
What plane does a Lat Ceph not assess
Transverse - need Posterio-anterior cephalomatric x-ray
Lat Cephs are used to assess
a) vertical features
b) Anterior-posterior features
c) Transverse features
A and B
How much is the radiation dose from an OPG
54uSv
How much is the radiation dose from a full mouth series of x-rays
150uSv
Most noticeable differences between malocclusions occur in the transverse plane
True or false
False!
Vertical and AP most common
What is the magnification of a Lat Ceph
7-8%
What Lat Ceph measurements compare the position of the maxilla and mandible, with the cranial base
- SNA
- SNB
Analysis of Relationship of the maxilla and mandible with the occlusal plane on a lat ceph is called:
wits analysis
Which of these is NOT used in assessment of vertical skeletal pattern
a) FMPA
b) MMPA
c) Facial Proportion
d) ANB
d) ANB
Which of these is not used to assess antero-posterior skeletal patten on a lat ceph:
a) SNA
b) FMPA
c) ANB
d) ) Wits
FMPA
Which of these is not used to assess incisor position on a lat ceph
a) Wits
b) UIA
c) LIA
d) Interincisal angle
a) wits
Line from soft tissue chin to the upper lip
Holdaway H line
What two lines are used for soft tissue analysis on a lat ceph
- Holdaway H line
- Rickett E plane
What three methods are most often used to treat skeletal discrepancies
- Orthodontic camouflage
- Growth modification
- Orthodontics and surgical tx
What is usualy used to fix antero-posterior issues of dental origin (Class I, II and III BSI)
- Fixed appliances
- Removable appliances
What is usually used to treat Antero-posterior problems of skeletal origin (3)
- Growth modification (functional appliances)
- Surgical tx
- Orthodontic camouflage tx
The optimal timing of functional appliances is during pubertal growth spurt. How is the growth stage of an individual determined
Assessment of:
- Cervical vertebra
- Hand/wrist
- Dental age
- Peak heigh velocity
- Secondary sex characteristic
What functional appliances are used for tx of mandibular retrusion (tx of class II)
Headgear (high, cervical or combination)
2 examples of removable functional appliance, and one example of fixed, for the tx of skeletal class II
- Van Beek
- Twin Blocks
- Hebst and Forsus (fixed)
2 functional appliances used for tx of skeletal class III
- Chin cap
- Face mask
When might surgery be used to tx skeletal antero-posterior discrepanyc?
- Patient over 18 so no longer growing
- Severe skeletal discrepancy
Overbite is usually anything over:
2mm
5 causes of long face/open bite
- Habits eg thumb sucking
- Mouth breathing (resulting in overeruption post)
- Tongue thrust
- Loss of condylar height
- Myotonic dystrophy
Four methods of treating deep bites
- Removable or fixed bite plane
- Fixed ortho
- Cervical headgear
- Orthognathic surgery
Stability of tx of deep bite depends on:
Good incisor angulation
Posterior Crossbites are common in primary and early mixed dentition.
True or false
True 8-20% of children
5 causes of posterior crossbite
- Crowding
- Inherited pattern
- Funcitonal influences - sucking habits, impaired nasal breathing, sleeping posture
- Developmental defect
- Trauma
Posterior crossbites of dento-alveolar origin usually involve how many teeth:
1-2. Tilted toward midline.
What is usually the cause of a skeletal posterior crossbite?
Narrowed maxilla. Teeth appear to tip outward.
Most unilateral posterior crossbites are functional.
True or false
True.
Midline shift.
What are the two most common RME devices
Haas (tooth-tissue borne)
Hyrax (tooth borne)
What type of appliance is this?
Haas maxillary expansion device
What is this?
Hyrax type maxillary expander
What is often used for slowQ maxillary expansion
- Quad helix
- Upper removable device
Lateral cant of the occlusal plane should be measured in comparison with:
Inter-commisure line AND inter-pupillary line
2 methods of treating anterior crossbite:
- URA
- 2x4
When is the most appropriate time to carry out a full orthodontic assessment?
- Late mixed dentition
- 10 for girls
- 11 for boys
What is often used to maintain space in the lower arch
Lingual arch retainer
Why is care needed for the exo of ankylosed teeth?
CAn cause extensive bone loss.
The normal PDL space is approximately how wide
0.5mm
What medications should not be prescribed to patients undergoing ortho treatment
- NSAIDs
- Corticosteroids
- Bisphosphonates
Classic case for a functional appliance:
Class II, Div I
Four contra-indications for functional appliances
- Non growing patient
- Dolicofacial
- Anterior open bite
- Problined lower incisors
What name and type of appliance is this?
Twin block
What name and type of appliance is this?
Activator
Functional appliance
When might functional appliances be recommended over traditional ortho?
When there is a significant risk of trauma in youth eg sports?
Otherwise, late stage ortho same benefits
What type of clasp is this?
Adams clasp
What are these?
Hawley Retainers
(a passive removable retainer to keep teeth in place)
What are molar bands used for in ortho?
They allow attachment of heavy duty appliances like headgear. stronger than bonded brackets.
Anomalous lateral incisors are associated with:
Palatally ectopic canines
Which of the folloiwng is NOT a cause of midline diastema
a) tooth size discrepancy
b) angulation of teeth
c) habits
d) soft tissue
e) hard tissue
e) hard tissue
Which is the following is NOT an advantage of interception orthodontic treatment
a) Conservative tx
b) prevent future needs
c) stability of tx
d) allow normal occlusal development
c) stability of tx
Which of the following is correct?
a) Central incisors usually erupt at 5 years
b) lateral incisors usually erupt at 5 years
c) third molars are present in the jaw from 3 years
d) most people tend to have all their teeth erupted by age 10
e) canines are the second most commonly impacted tooth
e)
4 complications of impacted canines:
- Resorption of laterals
- Ankylosis
- Aesthetics
- Pathology (dentigerous cyst)
3 causes of impacted canines
- Supernumeraries
- Crowding
- Trauma
Large OJ/OB can be an indicator of maxillary excess
True or false
True
Anterior crossbites in the permanent dentition are important to treat, because they can lead to:
Labial wear and functional shift
Options for tx of congeintally missing lateral incisor:
- Canine substitution
- Maryland bridge
- Implant
- Autotransplantation
Tx for missing premolars:
If spacing - preserve Es
If crowded - extract Es where appropriate
What % of midline diastemas are due to supernumeraries?
10%
What are 5 clinical signs of supernumeraries
- Spacing eg diastema
- Failure of adjacent teeth to erupt
- Displacement
- Eruption into mouth
- Local crowding or irregularity
Teeth which are often ectopic:
- Upper 6’s
- lower incisors
- canines
What is the difference between reversible and irreversible ectopic eruption of upper first molars
Reversible - the tooth spontaneously frees itself and erupts into occlusion. Deciduous tooth remains with distal surface partly resorbed.
Irreversible - permanent molar stays locked into the pack of the E, resulting in premature exfoliation of E. If not tx provided space is lost.
What % of ectopic upper first molars spontaneously correct?
60%
Impacted maxillary canines should be monitored for months at most
12
3 options for tx of palatally impacted canines:
- Early extraction of deciduous canine (at age of 10-13)
- Surgical exposure of canine and extrusion
- Make space with fixed appliances or exo of premolar
List 8 aetiologies of diastemas
- Genetic
- Developmental
- Tooth size discrepancy
- Angulation of teeth
- Soft tissue
- Habits
- Iatrogenic causes
- Pathology
What are the four main components of removable appliances
- Base plate
- Retentive components
- Active components
- Anchorage
What is the definition of anchorage
“Resistance to unwanted tooth movement”
When rebonding lingual retainers it is important that they are bonded:
a) actively
b) passivey
b) passively!
Should just be sitting against the tooth - no force! If you can’t achieve this - refer!
What way should you seat patient to assess skeletal classification?
Profile
What are 2x4 devices used to tx?
Anterior crossbite
What is this, what does it do, how does it work?
Lingual holding arch. Maintains space by preventing molars from migrating forward. Also used to resolve anterior crowding
What is this? What does it do?
Trans-palatal arch.
Helps de-rotate 6s, and can be activated to do expansion at molars.
What is this? What does it do?
Quad helix. Arch expansion and de-rotation but mostly through tooth tipping.
Good for crossbites.
What is this and what is it used for?
Anterior bite plane.
Correct deep bite by allowing posterior eruption.
What this device?
Hyrax device.
Arch expannder
What is this and what is it used for?
Twin Blocks.
Removable class 2 device.
What is this?
Herbst fixed functional device.
For class II
If primary molars are lost after the age of , the impact on space is likely to be less significant.
9
Sequelae of loss of arch length (due to early primary molar loss)
- Crowding
- Ecropic eruption
- Palatal impaction
- Crossbite formation
- Centreline discrepancies
6 contraindications for space maintainers
- When the permanent successor is about to erupt
- Where parent or child cooperation and/or oral hygiene, dental care is doubtful
- There are missing permanent teeth
- When there is a well-developed occlusion with cuspal interdigitation or where over-eruption of opposing teeth will prevent space closing
- In the mandibular arch Class III with spaced arch
- Severe crowding
List 3 fixed unilateral space maintainers
- Band and loop
- Crown and loop
- Distal shoe
List 4 fixed and bilateral space maintainers
- Lingual arch
- Palatal arch
- Nance button
- Lip bumper
What is this?
Band and loop
What is this?
Distal shoe
A four year old is missing a second primary molar. In your judgement, is the child in need of a space maintainer .
Yes. To prevent mesial eruption of 6. But check first that the 5s are present.
Use a distal Shoe.
Does this situation require a space maintainer?
Yes. Distal shoe.
A 6 year old child is missing their mandibular right first primary molar. In your judgement is the child in need of a space maintainer? If so, would you use a removal or a fixed space maintainer?
Yes. Band and loop. Fixed due to compliance.
Will prevent midline shift.
Is a space maintainer required here?
No because symmetrical but could consider for aesthetics and function
What is the leeway space in the maxilla?
0.9-1.5mm per side
What is the leeway space in the mandible?
1.7-2.5mm per side
Odontoma with an orderly fashion of tooth like structure. Commonly seen in anterior maxilla.
Compound odontoma
Odomtoma with disordered tissues, commonly seen in posterior mandible
Complex odontoma
Which of these is not a type of supernumerary:
a) Peg/Conical
b) Odontoma
c) Supplemental
d) Tuberculate
e) Comparable
e)
Managment of submerged (ankylosed) teeth.
Usually due to missing successor.
Discuss with ortho or pros. Surgical removal with minimum damage to alveolus if followed by ortho.
About 2% of the population suffer from an unerupted maxillary canine, and about % palatal.
85%
5 Indications for radiological investigation of maxillary canine:
- Inability to palpate by age 10
- Asymmetry in palpation or eruption of canine
- Missing or abnormal lateral incisor
- Canine bulge in wrong place
- Retained deciduous canine
About % of patients with median diastema have an abnormal:
fraenum
