Orthodontics Flashcards
When should you refer patient for orthodontic assessment?
deciduous dentition - CLP, craniofacial abnormalities (if not under MDT care) early mixed dentition - delayed eruption of perm incisors, impaction/FOE of 6s, poor prognosis of 6s, severe class 3, AXB, ectopic canines, pathology late mixed dentition - growth mod in class 2, hypodontia, other routine problems
What is ideal occlusion?
anatomically perfect arrangement of teeth
what is normal occlusion?
acceptable variation from the ideal
what are competent lips?
lips meet with minimal or no muscle activity
what are incompetent lips?
evident muscle activity is needed to make lips meet
Class I incisor relationship
lower incisors occlude with or lie immediately below cingulum of upper incisors
Class II incisor relationship
lower incisor edges lie posterior to cingulum of upper incisors
div 1 - max centrals are upright or proclined, OJ increased
div 2 - max centrals retroclined, OJ usually decreased, may be increased
Class III incisor relationship
lower incisors lie anterior to cingulum of upper incisors, OJ is decreased or reversed
OJ and OB
OJ - distance between max and mand incisors in horizontal plane
OB - overlap of incisors in vertical plane
Complete vs incomplete OB
Complete - lower incisors contact upper incisors or palatal mucosa
incomplete - they dont
Anterior Open bite
no vertical overlap of incisors when the buccal segments are in contact
Crossbites
deviation from normal bucco-lingual relationship
- lingual - buccal cusps of lower molars occlude lingually to lingual cusps of upper
- buccal - buccal cusps of lower per/molars occlude buccally to buccal cusps of uppers
Dento-alveolar compensation
inclination of the teeth to compensate for underlying skeletal abnormalities
Why are study models taken?
clinical records, legal documents, show what could be achievable, show what has changed, show the final treatment position
What indices are used for assessing orthodontic need
IOTN - grade 1 - minor malocclusions grade 2 - minimal need grade 3 - moderate need - use the aesthetic component grade 4 - great need grade 5 - very great
grade 4/5 get NHS treatment
grade 3 needs aesthetic component of 6+
How do you assess the dental health component?
MOCDOO Missing teeth overjet crossbite displacement overbite other
What are the cephalometric points used in ortho assessment? and what are the common values
Sella, nasion, orbitale, porion (EAM), anterior nasal spine, posterior nasal spine, gonion, menton, A point, B point Frankfort plane = porion-orbitale maxillary plane = PNS-ANS mandibular plane = gonion - menton SNA = 81 +/-3 SNB = 79 +/-3 ANB = 3 +/-2 Max = 109 +/-6 Mand = 93 +/- 6 MMPA = 27 +/-4 facial proportion (LAFH) = 55
What are balancing extractions and compensating extractions?
balancing - extraction of same/adjacent tooth on the opposite side of the same arch - preserves symmetry
compensating - extract of occluding tooth on the opposing arch. stops over eruption
When do you extract FPM?
poor prognosis, need calcification of the furcation of the 7s as optimal.
if late - little space closure and 7 tilts mesially
if early - get crowding
What is a median diastema, what causes it and how to treat
Diastema - gap between central incisors. 6yo = 98%, 12yo = 7%
caused by small teeth, absent/peg laterals, midline discrepancy, proclination of ULS, physiological from pressure of developing teeth on roots, fraenum
treatment - wait. before 3s erupt and <3mm
after 3s - ortho Tx and retention.
Anchorage options for distal movement
temporary anchorage devices are preferred to headgear
How to treat buccally displaced max 3s
if crowded - XLA 4s and fixed applicances
ortho Tx - buccal canine retractor
How to treat impacted canines
- do nothing and monitor for pathology
- XLA 3s, restorative to close space (possible trauma from XLA, fixed treatment)
- open exposure of 3s, ortho Tx to pull down (only if in favourable position, takes a while, fixed Tx and requires good cooperation)
- autotransplantation - not always successful, can cause ankylosis/necrosis
Causes of increased OJ
Skeletal pattern, soft tissues, lip trap, habits, crowding
management of increased OJ
fixed appliances for class I and II to retract ULA, +/- XLA.
functional appliance in class II to tilt teeth/growth mod
ortho camouflage
surgical correction if severe
Causes of increased OB
normal is 1/2-1/3 overlap.
increased is associated with class II/2
only treat if traumatic.
decreased LFH, high lower lip, retroclined incisors, increased inter incisal angle
how to treat increased OB
FABP to allow molars to erupt
procline lower incisors
Cause of AOB
vertical growth > horizontal growth
habits, tongue thrust, iatrogenic, CLP
Treatment of AOB
cease habit, FPBP
Treatment of reverse OJ
- Do nothing and accept
- camouflage
- surgery if ANB below -4
lower incisal angle to mand plan <80
How do you treat XB?
AXB - z spring and FPBP to disclude teeth
PXB - quad helix, RME, midline palatal screw and FPBP
what are indications for removable appliances?
Require movement of blocs of teeth (PXB) interceptive treatment in mixed dentition (AXB) overbite reduction elimination of occlusal interferences spacemaintainer when passive retention when passive habit deterrent
What are the active components of removable appliances and what are they made out of
Z springs - 0.5mm HSSW
buccal canine retractor
roberts retractor
midline palatal screw
What are the retentive components of removable appliances and what are they made out of?
Adams cribs - 0.7mm HSSW (0.6mm on deciduous)
southend clasp
labial bow
What are the components of fixed orthodontic appliances?
Bands - on molars
Brackets - on each teeth, usually labial surfaces
Archwire - active component. NiTi or steel.
ligatures - elastic bands or wire to hold archwire in bracket
can have class II or class III inter arch bands
What is the mode of action of functional appliances? and give an example of one
25% skeletal change, 75% dental tooth tipping
twin block appliance
What information would you give a patient who has jsut been given their removable appliance?
- non compliance with significantly increase your treatment time
- it will feel big, you will salivate more and you will find it hard to talk. practice and these will aleviate
- wear is 24/7 except contact sports and swimming. clean after meals with toothbrush over filled sink
- if it breaks, come back
- some discomfort initially is to be expected - it means it is working. this will reduce
- emergency contact details
How does a twin block appliance work?
retroclination of upper anteriors
proclination of lower anteriors
mid line palatal screw frequently incorportated to tip posterior teeth to correct PCB
re-positions mandible forward
reduces muscle action on jaws
some skeletal grown from secondary growth centres
correcting AOB with posterior bite planes and allows further eruption of anteriors
What is dento-alveolar compensation?
a system which attempts to maintain normal inter arch relationships
can maintain occlusal relationship even though there are variations in growth and facial pattern
What is a supernumerary tooth?
a tooth that is in addition to the regular dentition
What are TADs and why are they used?
temporary anchorage devices - mini implants to provide anchorage for ortho treatment no osseointegration easily placed absolute anchorage removable patient compliance unnecessary
Who is involved in treating a patient with class III malocclusion
psychology ortho surgical technologist restorative speech and language therapy oral hygeine
list the steps involved in class III malocclusion treatment
tooth alignment, eliminating crowding/spaces and XB coordination of the arches decompensate incisors flatten occlusal plane surgical fixatoin port surgery ortho
What different orthognathic surgeries are carried out?
Le fort 1 osteotomy
ant max osteotomy
BSSO
genioplasty
What are the risk/benefits you need to discuss with a patient who has carious 6s but wants ortho Tx?
- removal of 6s, tipping of 7s, loss of bone, spaces
- long term prognosis of 6s
- LA/GA for Xn, risk of death if GA
- risks of ortho Tx
What are some risks of orthodontic treatment?
- root resorption
- relapse
- failure to complete treatment
- treatment failure
- devitalising of tooth
- pain
- trauma from components
- decalcification of tooth
when would you treat an anterior open bite?
if mand displacement on closing
if traumatic
aesthetics
What characteristics of a malocclusion would make it ideal for treatment with a URA
- palatally tipped teeth
- 1 or 2 teeth needing movement
- class 1 molar relationship
- space
What are causes of ectopic canines?
- ectopic crypt position
- absent laterals
- crowding
- retention of deciduous canine
- genetics
How do you monitor the eruption of canines?
palpation from 9/10
look at inclination of 2s
mobility of cs
colour of cs
What are the signs of impacted canines?
- delayed eruption
- retained Cs
- unable to palpate
- distal tipping of 2s
loss of vitality or mobility of 1s/2s
What are functions of a URA other than tipping teeth?
- space maintainer
- habit breaker
- retainer
- correct OB
What warnings do you give someone on provision of a URA?
- big and bulky
- non compliance increases duration
- will feel uncomfortable, saliva, speech - will settle
- beware of hot drinks
Waht instructions do you provide to somone when you have them a URA?
- wear 24hs
- remove for contact sport or swimming
- clean after eating with soft brush and water
- dont eat hard or sticky foods
What do you use in a URA to correct an ACB and a PCB?
ACB - Z spring
PCB - midline palatal screw
What are the signs of a digit sucking habit?
narrow and high palate PCB AOB ACB increased OJ proclined uppers/retroclined lowers
What are risks of bonded and pressure formed retainers?
bonded:
can debond, caries, gingivitis, poor OH, fracture of wire
pressure:
lost/chewed by dog
compliance and no longer fitting, keeping clean
How would you assess vertical skeletal relationship?
LAFH vs TFH - should be 50% ish
FMPA - should meet at the back of the head
What special investigations would you do for a patient before referring them on to ortho?
study models and bite recording
lateral ceph -
What are some causes of AOB?
digit sucking
tongue thrust
fracture of mandible
skeletal discrepancy
How would you monitor canine movement?
measure, can use a definite point to compare against
what are different types of orthodontic retention?
hawley retainer
vacuum formed retainer
fixed bonded retainer
A patient with fixed ortho presents with white areas around the brackets, what could be the cause?
- demineralisation
- excess cements
- plaque
How does a URA affect the anterio-posterior skeletal relationship?
it doesnt
How does a URA affect the vertical skeletal relationship?
FABP would decrease overbite and increased LAFH
What would cause the failure of removal of infected material during RCT?
inadequate apical shaping
indadequate coronal flare
inadequate irrigation
apical stop too coronal
a. Why might a tooth restored with MOD amalgam fracture?
b. What could be done to prevent this?
a. amalgam not bonded to tooth tissue - unsupported enamel more likely to fracture
buccal cusps can be thin
parafunction
margins on occlusal contacts
b. bond with panavia porcelain inlay composite crown good preparation
Why would a fixed/fixed adhesive bridge debond?
poor prep poor bonding technique incorrect occlusal forces different pathways for torque caries
Why is a single wing of a fixed/fixed bonded bridge debonding a bad thing?
difficult to clean underneath, cant move. can get caries developing underneath
patient might not know
what are andrews 6 keys?
- tight contacts, no rotations
- class I incisors
- class I molars
- flat occlusal plane
- long axis is slightly mesial
- crowns canines back are lingually inclined
What are different surgical procedures for orthognathic surgery?
Le fort 1 anterior maxillary osteotomoy advancement BSSO set back (VSSO) genioplasty
design a URA for retroclining anterior teeth
- Active: Roberts retractor 0.5mm in tubing
- Retention: Adams cribs 6/6 0.7mm HSSW
- ?Anchorage: Stops mesial to 3/3?
- Baseplate: Flat anterior biteplane
