Orthodontics Flashcards
List any 3 uses of a URA apart from tipping and tilting teeth
* Habit breaker
* Space maintainer
* Reduce overbite (FABP)
* Retainer
* Dont say maxillary expansion as technically this does tip and tilt teeth
What is the patients malocclusion type, skeletal pattern and incisal relationship?
Class II division I
Class II skeletal base (moderate)
Class II division I incisors.
Retrognathic mandible.
High FMPA
In general, what are the possible aetiological factors Class II division I malocclusion?
Skeletal II pattern (retrognathic mandible, prognathic maxilla).
Soft tissues - lower lip trap.
Strap like lower lip may retrocline the lower incisors.
Digit habits.
Dental - increased overjet could be due to crowding/ectopic upper incisor
In addition to having an OPT, what other ways (clinical and radiographic), can be used to assess the position of an unerupted canine?
* Palpate for unerupted 3s, buccal and palatal.
* Check for mobility of Cs and 2s
* Take an anterior occlusal maxilla radiograph
* Take 2 x PAs
* Use parallax to localise the tooth
* CBCT
What is the risk of providing no treatment in a patient with an IOTN of 5a?
* Trauma to upper incisors.
* Psychosocial issues (bullying due to appearance)
* If patient is still growing, same options may not be available once they stop growing.
* Crowded arch could lead to impaction of teeth
An orthodontic patients mother has heard that braces can shorten the length of her sons roots. She wants to know if this is true, and can it be avoided?
Yes. A course of FA treatment can lead to root resorption of all of the teeth connected to the appliance. Usually by around 1mm, and at this level there is not any long term clinical significance.
Some patients experience a greater degree of resorption but this is not entirely predictable.
Possible risk factors are; short pretreatment root length or unusually shaped roots, previous dentoalveolar trauma, nail biting habits, genetic predisposition, metabolic factors, treatment length, distance tooth moved, higher forces and intrusive forces more likely to cause root resorption.
Management inlcudes; identifying at risk cases, radiographic monitoring of patients with increased susceptability, leave short rooted teeth off of appliace, orthodontist to manage forces appropriately, keep treatment time short, discontinue treatment if root resorption progressing.
This patient is going to have both upper first premolars extracted to allow eruption of the upper canines. Give a design suitable for a removable space maintainer
* ARAB; Active components, Retentive components, Anchorage, Baseplate
*A none
*R Adams clasps 16, 26 in 0.7mm HSSW
Southend clasp 11, 21 in 0.7mm HSSW
*A yes, offered by base plate
* B Baseplate in self cure PMMA
Besides a URA what other type of space maintainer could be used?
* Fixed palatal arch
* Fixed palatal arch with nance button
How would you gauge if a patient has been wearing their appliance as instructed?
* Ask the patient how they’ve been getting on
* Have the teeth moved?
* The patient can handle the appliance well
* The active components are now passive
* The patients speech is no longer effected
* The patient no longer produces excess saliva
* There are visible signs of wear on the patients soft tissues
* There are signs of wear on the acrylic
* The appliance may be discoloured
What are the eruption dates of the primary dentition?
A 6-7 mon
B 7-8 mon
C 18-20 mon
D 12-15 mon
E 24-36 mon
What are the eruption dates of the permanent dentition?
1 - 6/7 y
2 - 7/8 y
3 - 11/12 y
4 - 11y
5 - 12 y
6 - 6 y
7 - 12 y
8 - 16-21 y
At what age would you expect crown formation to be complete?
Central incisors - 3-5 years
Lateral incisors 3-6 years
Canines 4-6 years
First premolars 5-7 years
Second premolars 6-7 years
First molars 2-4 years
Second molars 6-7 years
At what age does crown formation begin?
Central incisor 3-4 months
Lateral incisor 3-12 months
Canine 4-5 months
First premolar 18-24 months
Second premolar 24-30 months
First molar 7-8 months after ovulation
Second molar 30-36 months
At what age would you expect root formation to be complete?
Central incisors 8-10 years
Lateral incisors 8-10 years
Canine 8-13 years
First premolar 11-13 years
Second premolar 11-14 years
First molar 8-11 years
Second molar 11-16 years
What is the DHC of the IOTN hierarchial scale?
MOCDO
Missing teeth
Overjet
Crossbite
Displacement of contact points
Overbites (inc open bite)
What are the 6 components of a DHC grade 5?
5i - Impacted teeth due to crowding, displacement, the presence of supernumerary teeth, retained deciduous teeth and any other pathological cause.
5h - Extensive hypodontial with restorative implications (more than one tooth missing in any quadrant) requiring pre restorative ortho
5a - Increased overjet .9mm
5m - Reverse overjet .3.5mm with reported masticatory and speech difficulties
5p - defects of cleft lip and palate and other craniofacial anomalies
5s - submerged deciduous teeth
What are the 11 components of a DHC grade 4?
4h - less extensive hypodontia
4a - overjet .6mm but ,9mm
4b - reverse oj .3.5mm with no recorded masticatory or speech difficulties
4m - same as b with masticatory or speech difficulties
4c - Ant or post crossbites with .2mm discrepancy between RCP and ICP
4l - Post lingual crossbite with no functional occlusal contact
4d - Severe contact displacement .4mm
4f - Increased and complete overbite with gingival or palatal trauma
4t - PE teeth, tipped and impacted against adjacent teeth
4x - Presence of supernumary teeth
Name some general aetiological factors of malocclusion
* Skeletal; size, shape and relative positions of the upper and lower jaws.
* Muscular; Form and function of the muscles that surround the teeth (lips, cheeks, tongue)
* Dentoalveolar; size of the teeth in relation to the size of the jaws
What is the aetiology of skeletal variation?
Genetic and environmental factors. Strong hereditary component to shape of face and jaws. Possible environmental factors include masticatory muscles, mouth breathing, head posture
What are the aetiological factors of class ii malocclusion
* Mandible placed posterior relative to maxilla
* Mandible too small (most commonly), maxilla too large or combination of both
* Mandible normally sized but placed too far back due to obtuse cranial base angle.
* Teeth erupt into post normal occlusion
* SNA usually average but may be increased if maxilla prognathic
* SNB usually decreased
* ANB >5 degrees
What are the aetiological factors of class iii malocclusion
* Mandible placed anteriorly relative to maxilla.
* Maxilla too small (most commonly), mandible too large, or combination of both
* Normally sized jaws but mandible positioned too far forwards due to acute cranial base angle.
* Teeth erupt into pre-normal occlusion
* Expect SNA to be decreased if maxilla deficient
* SNB often average but may be increased if mandible prognathic
* ANB <1 degree or negative
What are some causes of facial asymmetries?
Dental cause; displacement of normal mandible due to unilateral crossbite.
True mandibular asymmetry; hemi-mandibular hyperplasia/elongation. Condylar hyperplasia
A patient has a 12mm OJ, well aligned arches and ectopic canines. What are the complications of these features?
Trauma risk.
Difficulty speaking
Difficulty eating
Psychological aspects
Root resorption of adjacent teeth
What are the dental complications of a retainer?
Fixed retainer; can debond. Can fracture. Increased risk of gingivitis. More difficult to clean/maintain OH
Removable; can be lost. Can alter occlusion. Can be chipped/fractured. Can be removed - pt compliance.
What would be the URA design to correct a posterior crossbite?
Aim; to correct posterior crossbite.
Active component(s) - mid palatal screw
Retention; Adams clasps 16, 26, 14, 24
Anchorage; yes
Baseplate; Self cure PMMA and FPBP
What does right deviation of mandible on closing mean, what are two problems patient might suffer from if left untreated?
Mandibular displacement on closing due to inter arch discrepancy. TMD, parafunctional habit, tooth wear
List 8 potential risks of otho treatment besides decalcification
Root resorption.
Failure to complete treatment.
Loss of vitality.
Tooth wear.
Relapse.
Soft tissue irritation.
Gingival recession.
Loss of periodontal support.
Wear of adjacent teeth
How could you assess a patients AP relationship?
Visually. Palpate skeletal bases. Lateral cephalometry
Name four intraoral features an adult patient with class iii occlusion may have
Reverse or reduced overjet. Displacement on closing. Retroclined lower teeth. Attition
Design a URA to correct an anterior crossbite on tooth 12.
Aim - to correct crossbite tooth 12
A - Palatal z spring 12 in 0.5mm HSSW
R - Adams clasps 16, 14, 24, 26
A - yes
B - self cured PMMA with posterior bite plane
What 5 factors can resist displacement forces?
Gravity. Active components. Tongue. Mastication. Speech
A patient attends for a routine check up half way through ortho treatment. You notice a debonded bracket and demineralisation around the remaining brackets. How would you manage each of these problems?
Account for components. Ask patient if they know what happened. Check health of teeth. If round wire remove ligature and bracket, if rectangular show patient how to clean properly. Make patient aware of the problem. Refer back to orthodontist.
A patient has their fixed appliance removed due to lack of compliance. Extraction of the upper central incisors and RPD is a potential treatment option. What would be the risks of A. Extracting the teeth and B provision of an RPD?
A, Loss of incisors, drifting of incisors. Resorption of bone. Labial profile.
B, Increased plaque, caries risk. Pt unhappy with aesthetics. Increased risk of perio disease. Psychological effects
What can cause failure of eruption of the permanent upper central incisors?
Trauma; ankylosis of A or hypoplasia of 1 may cause formation of odontome in a reactionary process.
Supernumerary; can be erupted or unerupted
What are the 3 types of supernumerary?
Mesiodens - conical.
Tuberculate - malformed premolars
Supplemental - extra teeth of normal morphology. Typically erups in correct position.
What is the aetiology of palatally ectopic canines?
Small laterals or small roots.
Missing laterals.
Typically class ii div ii
Why is it important to detect palatally ectopic canines and what is the recommended treatment?
If left, can start causing root resorption of teeth involved in impaction.
Erupt around 11/12 years, palpate from 9 years. If they cant be felt, take a radiograph.
Use the SLOB rule to determine location.
Tx - consider space creation; extract c’s or arch expansion or combination of both. If extracting c’s space maintainers may be necessary
When is it best to correct an anterior crossbite and why?
Best to correct in the mixed dentition.
Left untreated can lead to attrition of the labial surfaces of upper incisors, fractured lowers, increased mobility and gingival recession.
What is the aetiology and correction of a posterior crossbite?
Aetiology is normally a narrow upper arch.
Correction is not always essential. Treatment decision should be based on functional need.
Purpose of treatment is usually to expand the maxilla and eliminate any mandibular displacement.
Treatment with removable appliance or quadhelix (better ohi and similar long term stability)
What is the ideal time to extract 6s of poor prognosis
When bifurcation of 7s visible on radiographs (8.5-10 years). Allows 7 to drift mesially providing acceptable occlusion