orthodontics Flashcards
A Patient has an anterior crossbite and requires fixed appliance treatment;
Name 4 fluoride supplements you would give the patient to prevent
decalcification, naming the dose and frequency?
2x daily Duraphat toothpaste 2800ppm or 5000ppm
1x daily Mouthwash 225ppm 0.05%
1x daily Fluoride tablet 1mg
4x yearly (HR patients) Duraphat fluoride varnish 22,600ppm
Name other methods to prevent decalcification other than fluoride supplements? (3)
To prevent decalcification:
Oral hygiene instruction (before and during)
- Minimum 2x per day very thoroughly
- After every meal
- Use disclosing tablets
- Target gingival margins
- Target around each bracket
Diet advice
- Encourage non-cariogenic diet
- Educate impacts of sugar amounts and frequency
- advise using free gum to stimulate saliva (buffering)
Case selection of pxs for ortho
- good OH prior to tx
- motivated
- low caries risk
High risks patients have - pre-existing decal, erosion, caries history (Lots of restorative tx)
List 8 potential risks of orthodontic treatment other than decalcification?
- (Decalcification )
- Root resorption
- Relapse
- Soft tissue trauma
- Loss of vitality
- Poor/failed tx
(above are the most important)
_
* Recession
* Loss of perio support
* Headgear injuries
* Enamel fracture/toothwear
* Allergy
Patient is 30 years old and he is worried with his class 3 incisors relationship, How would you assess patients skeletal anterior-posterior relationship? (3)
with the frankfort plane horizontal to the floor;
- Visual examination
- palpate the skeletal bases
lateral cephalometry
List the the classes of AP relationship?
Class I: Maxilla 2-3mm in front of the mandible
Class II: Maxilla is > 3mm in front of the mandible
Class III: Mandible is in front of the maxilla (less than 2-3mm)
Teeth reduced/reversed overjet
Describe a class 3 anterior posterior skeletal relationship.
Class III: Mandible is in front of the maxilla
(maxilla is less than 2-3mm in front of the mandible)
Teeth reversed overjet
Name 4 special investigations an orthodontist would carry out before starting tx. (6)
(not special invetsiagtions)
Extra & Intra-oral examination
BPE
Radiographs: OPT, Lateral cephalometry
impressions for study models
clinical photographs
sensibility testing
Name 4 intra-oral features of a class 3 malocclusion.
- Class III incisors
- Often but not always C3 molars
- reversed/reduced overjet
- Reduced overbites or AOB present
- Crossbites (Anterior or posterior)
- Crowded maxilla
- Aligned or spaced mandible
- Dentoalveolar compensation commonly seen = proclined upper incisors and retroclined lower incisors
- Tendency for displacement (on closing) to achieve posterior contact
Name the systemic condition that causes the mandible to continue to grow.
Acromegaly - excess of growth hormone produced by the pituitary gland
e.g. via a pituitary adenoma (benign)
other symptoms:
enlarged hands and feet
enlarged facial tissue features e.g. nose, lips
How is a class 3 malocclusion managed? (5)
- Accept and monitor
Mild cases
- Used when Px has n concerns
- Used when px has no Dental health indications (displacement or attrition) - Early URA treatment to correct incisor relationship (e.g. crossbite)
- Growth modification- Reducing/redirecting mandibular growth and encourage maxillary growth via functional appliances e.g. Reverse twin block, Frankel III, protractiion headgear and rapid maxillary expansion.
- ortho camoflauge - maintain the underlying skeletal base relationship and create a class I incisor relationship (proclining UI +retrocline LI+ Correct overjet)
- Ortho + orthognathic surgery:
* Pt with aesthetic or functional concerns AFTER Growth is complete
* Moderate/Severe skeletal discrepancy
Patient attends with an anterior crossbite involving 21
- When is the best time to begin treatment?**
As soon as you detect it
What 3 features of the anterior crossbite involving 21 malocclusion would make it amenable to treatment with a URA? (4)
only single tooth movement
palatal tipping (can move to a positive overjet)
must have good overbite - aids stability
must have adequate space to move teeth forward
Design a URA for fixing an anterior crossbite involving 21.
Please construct a URA to correct the anterior crossbite on tooth 21:
A- 21 = Palatal Z spring (0.5mm HSSW)
R- Adam’s clasps (0.7mm HSSW) on the 14, 16, 24, 26
A- yes (1 tooth only)
B- Self cure PMMA with posterior bite plate.
What is hypodontia?
Congenital absence of one or more teeth (excluding the 8’s)
name syndromes associated with hypodontia. (4)
- Ectodermal Dysplasia
- Down Syndrome
- Cleft Palate
- Hurler’s syndrome
- Incontinentia pigmentii
how is hypodontia diagnosed? (2+5)
An examination and an x-ray are needed.
Observe:
* Early on in life
* Delayed or asymmetric eruption
* Retained or infra-occluded deciduous teeth
* Absent deciduous tooth = guaranteed absence of permanent
* Tooth form = tapered and small teeth commonly associated with hypodontia
how may hypodontia present to a GDP? (6)
- Delayed or asymmetric eruption
- Retained or infra-occluded deciduous teeth
- Absent deciduous tooth = guaranteed absence of permanent
- Tooth malformation = tapered and small teeth commonly associated with hypodontia
- ectopic canines
- Cleft lip and palate.
What are the possible tx options for hypodontia? (6)
- Accept
- Restorative tx alone
- Orthodontics tx alone
Combined orthodontic & restorative treatment:
- open space + restorative e.g. RPD, RBB, conventional Bridges, implant, autotransplantation.
- close space + no restorative (simple)
- close space + restorative (space closure plus)
Name 4 members of an MDT involved with hypodontia.
GDP - Recognition
orthodontist
prosthodontist
restorative
oral surgeon
Specifically the hypodontia clinic
Early tooth loss: What 4 factors worsen the effects of early loss of primary teeth? **
Age of the child
Which arch (loss in maxilla= worsen)
loss in an already crowded arch
which tooth is lost - E (worst).
when might you consider balancing a primary tooth
extraction? **
When there is planned loss of a primary C
- if you dont balance = midline shift
(optional)
When there is planned loss of a primary D
- more likely to balance on the other side if done under GA
(not routine)
When there is planned loss of a primary E = not routinely done however causes significant mesial drift of the permanent 6 = cause crowding
give 4 reasons for an unerupted central.
Early loss of primary teeth
prolonged retention of primary teeth
pathology
- Presence of a supernumerary
- Odontome
- Cystic formation
trauma = dilaceration of the root/crown
crowding upper labial segment
what are the treatment options for an unerupted central?(6)
- Do nothing
- If no supernumerary/pathology = Maintain space/create space and monitor for 1.5 years
- XLA supernumerary/ retained primary tooth and allow spontaneous eruption
- XLA supernumerary/ retained primary tooth and create space (URA or fixed)
- XLA supernumerary/ retained primary tooth and surgical exposure
- Closed exposure with gold chain if close to the surface and in the line of the arch
- open exposure
if > 9y/o use traction and fixed appliances
(bonded retainer after treatment)
- If significantly dilacerated or ankylosed = remove the incisor and maintain space
Class II div 1
- What is the BSI classification of class II div 1?
Where the lower incisal edges lie posterior to the cingulum plateau of the upper incisors
There is an increased overjet
The upper central incisors are proclined or of average inclincation
What are the dental features in class II div 1 patients? (5)
- Increased overjets
- Overbite varies (If deep- can have palatal trauma)
- Variable tooth position( good alignment, crowding or spacing)
- class ii Molar relationship
*Drying of gingivae & worsening of pre-existing gingivitis (Due to habitually parted lips)
What soft tissue problems are associated with class II div 1 malocclusion? (3)
Lower lip trap (getting behind incisors causing increased proclination of uppers)
Incompetent lips due to incisor prominence (increased trauma risk)
habitually parted lips = worsens pre-existing gingivitis
poor anterior oral seal
tongue thrust- to help achieve the anterior oral seal.
What are the 5 features of a twin block appliance?
2x bite blocks
Adams clasps
baseplate
labial bow
midpalatal screw
What makes a class II div 1 malocclusion amendable to correction via removable appliance therapy? (3)
If :
- very mild
- overjet is caused by proclined and spaced incisors
- If there is space to retrocline the UI by tipping & tilting movements.
-If there is an overbite = aids stability
What are the tx options for class II div1?
- Accept
- In a mildly increased overjet
- In a significant overjet but patient not concerned - Growth modification with functional appliances e.g. Twin block, Frankel 2, bionator, Herbst – act on underlying skeletal bases
- URA and Simple tipping of teeth
- Camouflage – fixed appliances correct incisor relationship without influencing the growth of the jaws. (may need extractions to allow retraction of teeth)
- Orthognathic surgery
When there is a severe anteroposterior skeletal discrepancy or vertical discrepancy
What is dentoalveolar compensation? **
The body’s attempt at creating a ‘normal’ occlusal relationship between the upper and lower arches when not it doesn’t occurring naturally.
Orthodontically-
E.g. proclination of UI by the tongue. Retroclination of LI by the lip.
Toothwear (compensation for loss of tooth surface)
E.g. the bone gets longer to prevent the incisal edge moving -leaving no room for restorations
what is the BSI classification of class III malocclusion.
Lower incisor edge occludes anterior to the cingulum plateau of the upper central incisor
The overjet is reduced or reversed
not all class 3’s have a reversed overjet - can be edge to edge
What 4 special investigations are carried out for class 3 patients?
Height and weight charts - to assess if patientis still growing
Radiographs: OPT, Lateral cephalometry
impressions for study models
clinical photographs
sensibility tests
List treatment options for class 3 malocclusion.
- Accept and monitor
-mild cases
- No patient concerns
- No Dental health indications (displacement or attrition) - Interceptive treatment (mixed dentition) e.g. a URA (functional appliance) to correct crossbite.
- Growth Modification- to redirect/reduce mandibular growth and encourage maxillary growth using:
Reverse Twin block/ protractor headgear/ bollard implants. - Orthodontic camouflage
Accept underlying skeletal base & using fixed appliances to achieve class 1 incisors by:
Proclining upper Incisors
Retroclining lower incisors
Correcting overjet. - Ortho + orthognathic surgery:
* Pt with aesthetic or functional concerns
* Growth completed
* Moderate/Severe skeletal discrepancy
Define a supernumerary.
An additional tooth or tooth like entity
Supernumerary teeth can be classified according to their position and / or shape. Please list and describe four different morphological types of supernumerary teeth you know of:
2020 Paper2
- Conical = cone shaped (most common)
- Tuberculate = barrel shaped, has tubercles
- Supplemental = looks like tooth of normal series however can be smaller (commonly a lateral incisor)
Both erupt - Keep whatever one is more suitable for orthodontic tx - Odontome = irregular mass of dental hard tissue
Can either be compound or complex
what are the effects of supernumeraries on the permanent dentition? (6)
2020 Paper 2
Delayed/failed eruption.
Displaces eruption of adjacent teeth causing an ectopic position.
Crowding.
Impaction
cyst formation (dentigerous cysts are associated with unerupted teeth)
root resorption of adjacent teeth
Child with mandibular displacement on closing on RHS with posterior unilateral cross bite of d, e and 6 on RHS
- What is mandibular displacement on closing?
2022 Paper 2 q25
Where the mandible to deviates to one side to achieve intercuspation.
This is because the interarch width discrepancy causes the upper and lower posterior teeth to meet cusp to cusp - mandible deviates to one side to prevent this and achieve ICP
Why would you correct a mandibular displacement? (4)
2022 paper 2 q25
Can lead to;
TMD
asymmetric growth
Tooth wear (attrition)
Gingival recession
What would you use to correct a unilateral posterior crossbite?
Provide design details.
2022 paper 2 q25
Please construct an URA to correct the Unilateral posterior crossbite.
A- midline palatal screw (baseplate cut as shwon in image)
R- Adam’s clasps (0.7mm HSSW) on 4s and 6s
A- baseplate provides
B- Self cure PMMA baseplate with flat posterior bite plane
Design the URA for a child with mandibular displacement on closing on RHS with posterior unilateral crossbite of d, e and 6 on RHS.
Please construct. an URA to correct the unilateral posterior crossbite.
A- Midline palatal screw (baseplate cut as shown in image)
R- Adams clasps on the Ds (0.6mm HSSW) and Adams clasps on the 6s (0.7mm HSSW)
A-
B- Self cure PMMA baseplate with flat posterior bite plane.
Give three uses of a URA other than tipping and tilting teeth (6)
Can be adapted to reducing an overbite
Retainer
habit breaker
space maintainer
expand upper arch
Write a prescription for a URA to reduce a 6mm OJ, 1st premolar have been extracted and previous URA retracted canines and reduced the overbite. Patient
has permanent dentition.
Aim: Please construct an upper removable appliance to reduce the overjet from the 12-22 and correct the overbite.
A: 11, 12,21, 22 – Roberts Retractor 0.5mm HSSW + 0.5mm ID tubing
13 + 23 – Mesial stops 0.7mm flattened HSSW
R: 16 + 26 = posterior retention Adams clasp 0.7mm HSSW
Roberts retractor also acts as retention
A: Yes and no – moving more than 2 teeth however the teeth we are moving have short roots.
B: Self cure PMMA + Flat anterior bite plane FABP (OJ + 3mm)
List 6 signs of good wearer/compliant patient with a URA on visit.
Patient arrives wearing the URA
Patient can insert and remove the URA easily
Can speak without impinging speech with URA
Device looks worn – wear on acrylic
Active component now passive as it needs to be re-activated again due to movement
Teeth have moved – 1mm per month
what are the difficulties experienced with URAs? (4)
1) The appliance will feel big and bulky – takes time for patient to get used to.
2) There will be mild discomfort and pressure on the teeth – indicates that this is working correctly (don’t use sore and pain)
3) Patient will initially have a lisp (Practice reading aloud to let tongue adapt to the appliance)
4) Initial production of lots of saliva – this will disappear over 24 hours.
What instructions would you give to the patient with a URA? (6)
1) Wear the appliance 24/7 including eating and sleeping
2) Take it out and clean it with a soft brush and soap under the luke warm tap after every meal
3) Put it in a protective container when carrying out contact (rugby) /active (sharp intake of breath) sports
4) Avoid hard and sticky food and exercise caution with hot food/drinks – heat is insulated as it acts as palatal coverage
5) Emphasise that non-compliance prolongs treatment
6) Provide emergency contact details – use if you have problems with the appliance
Outline the delivery of a URA steps. (4 & 6)
Check prior to fitting:
1) Make sure you have the correct appliance for the correct patient
2) Check that it matches the design
3) Run finger across it to ensure there are no sharp edges (safe for patient)
4) Make sure there are no signs of damage to the wirework (ensure integrity of the wirework)
Once in the patients mouth:
1) Ensure the fit doesn’t cause trauma – no blanching
2) Check the posterior retention – is it adequately going into the undercuts: check the flyover first and then the arrowhead in the undercut.
3) Check the anterior retention
4) Activate the appliance – The URA arrives passive- so we need to activate the active components. Activate a couple initially and active others later.Want to achieve 1mm movement open month. You can get the patient used to the appliance then come back and activate it later (not recommended as it prolongs the time)
5) Show them the correct way to put in and take out the appliance and get them to demonstrate this back to you.
6) See patients every 4 to 6 weeks
What 5 factors can cause displacement forces of a URA?
Tongue
Gravity
Mastication - patients should eat with the appliances in
Talking - creates vibrations through the palate
Active component - difficult to control
Patient has a 12mm overjet, well aligned arch and ectopic canines
- What are the possible complications of these features? (5)
OJ:
- trauma
- incompetent lips
- habitually parted lips = worsen pre-existing gingivitis
- difficulty speaking/eating
- psychological aspects - being teased
Ectopic canine:
- external resorption of adjacent teeth crown/roots
- cyst formation
- resorption of the canine crown
- ankylosis of the unerupted canine
What are the dental advantages and disadvantages of
fixed, holly and pressure vacuum formed retainers?
Fixed:
Advantages:
- Maintain corrections of diastemas/rotation
- Aesthetics
- Doesn’t interfere with the occlusal surfaces
- Compliance (attached 24/7)
- Cheaper (not for patient)
- Small and unobtrusive
Disadvantages;
- plaque trap
- Fracture and if composite debonds debris and sugars can leach beneath (must be checked at each check-ups)
- High failure rate (overbites and leading with upper ants when biting)
- Doesn’t incorporate all the teeth (no posterior retention)
Holly:
Disadvantages:
- Aesthetics poor
- Compliance poor because removable
- Bulky = affect speech and increased saliva
- Impinge on tongue space
- Problematic with lingual frenal attachment
- Expensive to produce
- Time consuming to produce
Advantages:
- Removable (for cleaning)
- Strongest and most resilient
- Incorporates all the teeth
- No tooth prep required
- No occlusal coverage = occlusal settling
- Can be adjusted to become active (passive to active and then can be made passive again)
Baseplate can provide anchorage when they become active
Thermoplastic:
Advantages:
- Aesthetics (if made correctly)
- Improved compliance
- Removable for cleaning
- Lower cost
- Incorporate all the teeth
- Can be altered (to stop at 6’a) if 7’s PE then get a new one when the 7’s erupted
- Better tolerated
- No tooth preparation
- Can correct minor tooth movements (become temporary positioner)
Disadvantages:
- Can break over time
- Stain and discoloured (when cleaned with toothbrush and toothpaste)
- If you don’t wear it, it doesn’t work/you can’t put them back in
- Doesn’t allow occlusal settling (props the bite open)
- Can cause caries if you wear after sugary foods/drinks
- Can deform when cleaning with boiling water
- Lost
- Use inappropriately for tooth whitening
Describe how bodily movement works in fixed appliances. (3)
- Move the tooth whilst maintaining it’s angulation
- Coordinated bone modelling and remodelling: allows resorption on pressure side side and deposition on the tension side.
- Allows tooth to move whilst maintaining a normal relationship with the periodontium
Define molar relationship
class 1: Mesiobuccal cusp of the upper 6 occludes with the buccal groove of the lower 6
Class 2: mesiobuccal cusp Anterior to the buccal fissure/groove
Class 3: Mesiobuccal Posterior to the buccal fissure/groove
Define incisor angulation
This is the relationship of the long axis of the tooth and the alveolar bone:
Angle of Upper Incisors to maxilla (109)
Angle of Lower Incisors to mandible (93)
