Ortho questions Flashcards
Name methods to prevent decalcification other than FV?
- Careful case selection
- fissure sealants
- fluoride supplements ( tablets , drops)
- fluoride mouthwash 225ppm
- High strength fluoride toothpaste
- OHI - correct toothbrushing and use of interdental brushes beneath wire and around brackets 2x daily
- Diet advice
- Regular hygiene appointments
List 8 other potential risks of orthodontics other than decalcification?
- relapse
- root resorption
- gingival recession
- trauma
- failure to complete treatment
- ulceration
- TMJ problems
- Risk of periodontal disease
- wear of adjacent teeth
- loss of periodontal support and vitality
- mucosal irritation
How would you assess a patient anterior-posterior relationship?
- visually with Frankfort plane parallel to floor
- Palpate skeletal bases at at two points (upper , lower)
- By lateral cephalometry - SNA - SNB = ANB
What are the classes of AP relationships?
- Class 1 - maxilla 2-3mm in-front of mandible (ANB 2-4)
- Class 2 - maxilla more than 2-3mm infront of mandible (ANB more than 4)
- Class 3 - mandible infront of maxilla (ANB less than 2)
Name 4 special investigations an orthodontist would do?
- Clinical photographs
- Study models
- Radiographs - OPT , lateral ceph
- Sensibility testing
Class 3 incisor relationship definition?
- Lower incisors edge lie anterior to the cingulum plateu of the upper central incisors
- Overjet is reduced or reversed
Name 8 intra-oral features of a class 3 malocclusion?
- reduced overbite , AOB may be present
- Posterior buccal or anterior crossbite
- reverse overjet
- maxilla often crowded
- mandible often aligned or spaced
- proclined upper incisors
- retroclined lower incisors
- tendency for displacement upon closing
What systemic disease causes the mandible to grow?
Acromegaly
How is a Class III malocclusion managed?
- Accept and monitor - if mild and pt still developing
- interceptive ortho URA - correct incisor relationship
- Growth modification ( functional appliance , headgear with RME to reduce and redirect mandibular growth , TAD’s)
- Camouflage - accept underlying skeletal base and correct incisors to class I
- Combined orthognathic and orthodontic treatment to correct functional and appearance issues
What functional appliances can be used for class III relationship?
- reverse twinblock
- frankel III
- chin up
Pt with anterior cross-bite
When is it best to begin ortho treatment?
Intercept as soon as detected with URA
Anterior crossbite involving 21
What featured of the malocclusion makes it suitable for treatment with a URA?
- Tooth in cross-bite is palatally tipped
- Good overbite (aids stability)
- Adequate space to move the teeth forward
Design a URA for fixing an anterior crossbite involving 21?
A - z spring on UR1 0.5 HSSW
R - adam’s clasp 16,26 0.7 mm HSSW + URd , ULd 0.6mm HSSW
A - only moving one tooth
B - selfcure PMMA with FPBP
URA for posterior cross bite
A - midline palatal screw
R - 16 + 26 + 24 + 14 adam’s clasp 0.7mm HSSW
A - reciprocal anchorage
B - self cure PMMA - posterior bite plane
URA for retracting canines
A - Palatal finger spring + gaurd ; 0.5mm HSSW
R - 6s adam’s clasp , 11+ 12 south end clasp 0.7mm HSSW
A - only moving 2 teeth
B - self cure PMMA
URA for moving canines palatally
A - buccal canine retractor + tubing
R - adam’s and south end clasp
A - y
B - selfcure PMMA
URA for overbite
A - robert’s retractor with I.D tubing
R - adam’s clasp 6s
A - y
B - self cure PMMA with anterior bite plane OJ +3mm
What syndromes are associated with hypodontia?
Cleft lip and palate
Axenfeld-rieger syndrome
Ectodermal dysplasia
Down’s syndrome
How may hypodontia present to you as a GDP?
- delayed or asymmetrical eruption
- retained or infra-occluded deciduous teeth
- Ectopic canines
- Absence of decidious teeth
- tooth malformation
Name members of MDT involved in treating hypodontia?
- othodontist
- restorative dentist
- paediatric dentist
- speech and language therapise
- Clinical psychologist
- Oral surgeon
- GDP
What factors can make early loss of primary teeth worse?
- Age of patient - early extraction is worse as will lead to premature eruption of permanent teeth
- space loss
- losing the E’s lead to issues with position of 6
- If it occurs in the maxilla its worse as more space is lost in upper than lower
- in crowded arches lead to evident space loss
- If it is in the anterior teeth will lead to psychological consequences affect appearance
When might you consider a balancing extraction of a primary tooth?
- balancing extractions are extraction of the same tooth in the same arch , this is to avoid centrelines shiftor relieve crowding
- Primary canines for centreline shift
- First primary molars for crowding
Give 4 reasons for an unerupted 1?
- supranumerary teeth (tuberculate)
- Trauma to A
- Crowding
- Pathology - dentigerous cyst
- Ankylosis
- Genetics
What are the treatment options for an impacted 11?
- Accept and monitor
- Surgical exposure and bonding using gold chain (over age of 9) using orthodontic traction
- XLA of supernumerary teeth if present
- Surgical extraction of 11
What is the BSI definition of Class II div 1 ?
- The lower incisor edges lie posterior to the cingulum plateau of the upper incisors
- Increased Overjet
- Upper incisors proclined or of average inclination
What dental features are seen in class II div 1 patients?
- proclined upper incisors or of average inclination
- Increased OJ
- Class 2 molars and canines
- overbite varies
- parted lips may lead to dry gingivae and can exacerbate gingivitis
What soft tissue features are associated with Class II div 1 patients?
- Incompetent lips due to incisor or skeletal relatoinship
- difficulty to achieve an anterior oral seal
- May have lip trap or tongue thrust
What are the 6 features of a twin-block appliance?
- consist of two separate bite blocks
- can have an expansion screw to widen the maxilla
- Has a anterior bow
- Adam cribs on teeth
- removable
- worn for 9-18 months
- deterrent rake can be added to prevent NNSH ( non - nutrusive sucking habit)
- can be adjusted to accommodate any changes
- have an interlocking mechanism
- tooth borne
How long should a twin block be worn for?
9-18 months
What makes a class II div 1 ammedable to correction with a functional appliance?
- Very mild class II
- Overjet is due to proclined or spaced incisors
- There is a favourable overbite
- only after specialised assessment
Usually URA have a very limited role in the treatment of inc overjet
How is the mandible postured when wearing a functional appliance?
- forward and downward
What are the treatment options for class 2 div 1
- accept and monitor
- Growth modification :twin block, frankel II , headgear or herbst
- URA - limited use but can use robert retractor
- fixed appliances
- Orthognathic surgery - when growth is complete and in severe cases
What is dentoalveolar compensation?
- A system the maintain normal inter-arch relationship by the mouth anatomical structures
- normal occlusion can normally be maintained by dento-alveolar compensation
Example of dentoalveolar compensation in class III malocclusion
Tongue Procline upper incisor
Lower lip Retrocline lowers
What 4 special investigations are done for class III patients?
- study models
- clinical photographs
- radiographs : lateral ceph ; OPT ; CBCT
- Planning models (Kesling) : setting up teeth to desired occlusion with wax
- sensibility testing
Define supernumerary teeth
- Tooth or tooth like entity found in the mouth which is additional to the normal series
What is the incidence of supernumerary teeth?
- most common in males
- found in anterior maxilla mostly
- 1% in primary and 2% in permanent
What are the types of supernumerary teeth?
- Conical
- Tuberculate
- Supplemental
- Odontome
What is a conical supernumerary?
- small peg shaped tooth
- close to midline
- Usually 1 or 2 in number
- May erupt but tend to prevent eruption
- May be high, inverted and symptoms free
What is a tuberculate supernumerary?
- Often paired and barrel shaped
- most common caused of failure of eruption of upper incisors
- Tend to not erupt
- need to be extracted
What is supplemental supernumerary?
- extra teeth of normal morphology
- usually an upper lateral or lower incisor
- can be 3rd premolar or 4th molar
- Often extracted due to form and position
What is an Odontome supernumerary tooth?
- Irregular mass of dental hard tissue
- can be compound which are discreet denticles
- can be complex as disorganised mass of dentine, pulp and enamel
What are 6 effects of supernumeraries on the permanent dentition?
- Diastemas
- Impaction (tuberculate cause impaction of 1)
- Displacement (crowding/spacing)
- Cyst formation
- Root resorption of surrounding teeth
- Crowding
What is mandibular displacement on closing?
- occurs when there is an inter-arch width discrepancy
- resulting in upper and lower teeth to meet cusp to cusp
- resulting in the mandible to be deviated to one side upon closing to achieve intercuspal contact position
Why would you correct a mandibular displacement?
- May cause TMD (best to intercept early)
- Tooth wear can occur
- May cause facial asymmetry
- May cause centrelines shift
- Teeth erupt in displaced ICP position
What would you use to correct a unilateral posterior crossbite?
- maxillary expansion with :
URA
Quadhelix
rapid maxillary expansion
Design a URA for someone with unilateral posterior crossbite
A - midline palatal screw 0.5 HSSW
R - Adam’s clasp on 6s and 4s or ds 0.7 HSSW (0.6 for primary)
A - reciprocal anchorage
B - Self cure acrylic + FPBP (must incorporate all posterior teeth to prevent unwanted tooth eruption)
Child present with ulceration , what 8 questions would you ask?
- where is the ulceration?
- is it getting better or worse?
- when did it appear?
- is there any blisters associated ?
- have these symptoms happened before?
- Is there any other area affected?
- Are there any other symptoms?
- Any other associated skin lesions?
- Any symptoms on the lips?
Patient present with ulcers on the lips what should you see intraorally ?
Herpes simplex primary infection
* Painful Erythmatous Swollen Gingivae
* Ulcers on lips, Gingivae and Extraoral mucosa
* Halitosis
Herpes labialis
* only present Extra-orally
Give uses of URA other than tipping and tilting of teeth
- Reduce overbite, overjet and crossbite
- Habit breaker
- Space maintainer
- Used as a retainer (HAWLEY)
- Expanding the arch
Write a prescription for URA to reduce a 6mm overjet and reduce overbite
ex question :
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 , pt has permanent dentition
A - Robert’s retractor with I.D tubing 0.5mm HSSW
R - Adam’s clasp on 16,26 - 0.7mm HSSW , Stops mesial of 23,13 0.6mm HSSW
A - ✔
B - self cure acrylic PMMA ; FABP (9mm)
List 6 signs of good wear and compliant patient on a URA on visit
- URA active component passive
- Signs of wear on URA ( acrylic part)
- patient can speak well with appliance
- no excess salivation
- patient can insert and remove URA easily
- teeth have moved (1mm per month)
- patient arrives wearing the URA
What are the difficulties experienced when wearing a URA?
- May have speaking difficulties at first - practice speaking with URA in loudly
- Excess salivation at first - should resolve within 24h
- May feel big and bulky but will get used to this
- Once activated may feel discomfort/pain but this means that the appliance is working
*
What instructions would you give to a patient wearing a URA?
- wear appliance 24/7 inculding meal times
- Avoid hard or sticky foods
- Take out and clean with soft brush after every meal
- Store in a safe container when playing contact sports
- non compliance will lengthen the treatment time
- be careful with hot foods and drinks
- give contact details in case of complications or failure of components
Outline the steps for delivering a URA?
- Check correct appliance for correct patient
- Check it matches prescription
- Check for any sharp edges and smooth
- Check wire integrity for areas of damage
- Try in the patient mouth
- Check for any signs of blanching, damage or trauma to soft tissue
- Check occlusion - flyover > arrowhead > anterior retention
- Adjust active component - 1mm movement per month
- Demonstrate to patient correct insertion and removal
When should you review a pt after giving them a URA?
Every 4-6 weeks
What factors can resist displacement forces of URA? (5)
- gravity
- mastication
- tongue
- talking/vibrations
- Active components
Patient has a 12mm overjet, well aligned arch and ectopic canines
What are the possible complications for these features?
- poor appearance - psychological effect
- Risk of trauma
- Root resorption of adjacent teeth
- Xerostomia
- Displacement on opening
- difficulty with mastication and speaking
What are the dental advantages and disadvantages of fixed dental retainer
Advantages
* does not need compliance
* good aesthetics
* no occlusal interference
* does not affect speech
*Cheap and easy to make
Disadvantages
* Only retains anteriors
* Oral hygiene issue
* Tooth is prepped with etch
* composite can debond
* high failure rate ( 50% debond in first 6 months)
What are the advantages and disadvantages of pressure vacuum formed retainer? (thermoplastic)
Advantages
* good aesthetics
* include all teeth
* cheap and easy to make
* good cooperation
* removable
* no prep to teeth
* does not cover palate
Disadvantages
* occlusal interference
* easily lost
* not as strong and resilient
* can be used for wrong purposes
What are the advantages and disadvantages of HAWLEY retainer?
Advantages
* removable
* incorporated all teeth
* no occlusal interference
* no prep to teeth
Disadvantages
* problem with compliance
* poor aesthetics
* big and bulky
* interfere with speech
* expensive
What information to provide to orthodontist regarding if pt needs ortho tx?
- patient details - name, DOB, CHI, address
- History (all)
- Orthodontic examination findings :
CO;HPC; expectations
Skeletal base A/P , vertical , transverse
Incisor relationship
IOTN score - radiographs
- study models
- photographs
During treatment , patient has a debonded bracket and demineralisation around remaining brackets , how would you manage this?
- never rebond the bracket
- Account for the components and ask how this happened ( refer to A&E) if suspected possible aspiration risk
- If wire is circular = remove ligature - take bracket off and give to pt
- Square wire = move bracket to side - clean underneath and show pt how to clean
- Give OHI regarding Fluoride use and apply FV to areas of demineralisation and explain to pt why it happens and how to prevent
- Refer back to ortho to replace bracket
child with removed ortho appliance due to poor compliance attends and asks about XLA of upper incisors and upper partial denture
What would be the potential long term risks of XLA of upper incisors?
- Spacing
- drifting of adjacent teeth
- problems with mastication
- aesthetic problem
- resorption of alveolar bone
child with removed ortho appliance due to poor compliance attends and asks about XLA of upper incisors and upper partial denture
What would be the potential long term risks of the RPD?
- increased plaque and increase of caries due to poor OH
- Increased risk of periodontal disease
- Poor aesthetics - psychological effects
- Harder to wear than fixed appliances
child with removed ortho appliance due to poor compliance attends and asks about XLA of upper incisors and upper partial denture
he does not want to wear a denture and asks for crowns, what would you advise against this option?
- Destructive - healthy tooth tissue will be removed
- More expensive than RPD
- Poor OH contraindicate crown placement
- Periodontal disease or recession will occur around crown due to poor OH resulting in an unaesthetic appearance
What are the oral signs of digit suckinig?
- Proclination of upper incisors
- Retroclination of lower incisors
- Localised AOB or incomplete OB
- Unilateral posterior Crossbite
What additions can be made to URA to break the habit of thumb sucking?
- Deterrent rake
- Hawley retainer (thumb appliance)
- Palatal crib
- Bluegrass appliance
Explain the effect of prolonged sucking habit on posterior dentition?
- thumb held in the mouth causes the mandible to drop open and and the tongue lies in a lower position
- this means the sucking action on the cheeks lead to narrowing of the maxillary dentition leading to posterior cross-bite (often unilateral)
What 4 methods can be used for stopping NNSH?
- Positive reinforcement
- Habit breaker URA
- Plaster on finger
- preventative nail varnish
- Gloves
- Fixed appliance with anterior rake habit breaker
What is the incidence of cleft lip and palate in the uk?
1:700 births
more common in males
What are the general health implications of CLP? (6)
- Hearing problems - otitis media with effusion (glue ears)
- Respiratory problems
- Higher risk of infection
- Problems with speech and mastication
- Poor aesthetics
- Congenital cardiac problems - atrioventricular canal defect
What are the dental features of cleft lip and palate?
- Increased caries risk
- High and narrow palate
- Hypodontia
- Crowding
- Growth problems - Class III malocclusion
- Impacted teeth
Outline 5 treatment stages of CLP patients?
3 months - lip closure
6-12 months - palate closure
8-10 years - alveolar bone graft
12-15 years - definitive orthodontics
18-20 years - orthognathic surgery
What causes CLP?
combination of
* genetic = syndromes, sex ratio, family history
* environmental = smoking, alcohol, multivitamins, anti-epileptics
What 5 members are involved in the management of CLP patients?
- maxillofacial surgery
- Cleft nurse
- Speech therapist
- ENT; respiratory team
- Geneticist
- Psychologist
- Dental team : Paeds, ortho, restorative, oral surgeon
What are the common complications of orthodontics?
- relapse
- gingival recession
- root resorption
- decalcification
How is relapse managed ?
- patient education and consent that ortho treatment require long term retention through a retainer at the end of treatment or teeth will revert back to previous alignment
- Explain that retainers should be worn lifelong to maintain orthodontic treatment results
How is decalcification managed?
- Patient education about the importance of oral hygiene compliance
- Use of fluoride toothpaste and supplements
- Education about Diet - cut out sugars
- FV can be applied
How to manage recession ?
- Patient education on importance of OH and OHI
- Gingival recession may be exacerbated by poor OH
- Tooth movement and brackets close to gingiva may cause some slight gingival recession
How to manage root resorption ?
- Explain to patient the risk of root resorption due to tooth movements and that it is minimal for about 1mm
- Excessive forces are limited in ortho
- Take pre and post tx OPT and PA to assess bone levels
Give other linked complications to ortho other than the main risks? (8)
- loss of vitality
- Trauma
- Mucosa irritation
- Periodontitis or gingivitis
- Failure to complete treatment
- Wear of adjacent teeth
- TMJ problems
- Ulceration
What are SnA , SnB and ANB
These are angles that measure the following:
* SnA - the anterio-posterior position of maxilla to the anterior cranial base
* SnB - the anterio-posterior position of the mandible to the anterior cranial base
* ANB = SnA-SnB - the anterio-posterior position of the maxilla to the mandible
What are the average values of SnA , SnB and ANB?
SnA = 81 ± 3
SnB = 78 ± 3
Anb = 3 ± 2
What is the average FMPA angle?
27 ± 4
What is the average incisor inclination
Upper = 109 ± 6
Lower = 93 ± 6
What is the ANB for Class I , Class II, Class III patients
Class I - 2-4
Class II - more than 4
Class III - less than 2
What percentage of 6-18 year olds have a diastema?
98% - 6 years old
49% - 11 years old
7% - 12- 18 years old
Give reasons for a diastema? (6)
- pathological causes
- proclined upper incisors
- generalised spacing
- midline supernumerary ( tuberculate)
- hypodontia
- Prominent frenulum
How are diastema’s managed?
- Accept and monitor - may correct with growth
- Treat the underlying cause
How to treat a diastema cause by generalised spacing?
Orthodontic management with or without restorative input
How to treat a diastema caused by hypodontia?
Orthodontics ± restorative management
How to treat a diastema caused by proclined upper incisors?
URA
How to treat a diastema caused by prominent frenulum?
Oral surgery to remove/reduce frenulum
How to treat a diastema caused by pathological causes ?
Oral med , oral surgery or maxfax
How to treat a diastema caused by a supernumerary tooth?
Oral surgery and orthodontics
What primary teeth are mostly infra-occluded?
lower D’s
more common in mandible
8-14%
How infra-occluded teeth appear clinically?
- metallic sound on percussion
- found lower in the arch compared to adjacent teeth
- no physiological mobility
How does infra-occluded teeth show radiographically?
- blurring or absence of PDL on radiograph
- external root resorption
What factors determine the management of infra- occluded teeth?
- presence or absence of permanent successor
- degree of infra-occlusion
- age of development
What are the treatment options for infraoccluded teeth?
- if permanent successor is present - monitor for 1 year as it may self fix , if it does not then extract
- If no permanent successor XLA as condition will worsen
Name components of a fixed appliance?
- bracket/tube
- bands
- modules - help bracket and wire to connect
- Auxiliaries - depends on type of movement achieved
- anchorage components
- force generating components
What are the components of a bracket?
- bracket slot
- tie wings
- bracket base
What materials can be used for brackets?
- metals ( Cocr, Au , Ti , SS)
- Polymers
- Ceramics
What is required before placement of bands?
- separator as it requires space
What material is used for bands?
Stainless steel with pre-welded attachments (tube or cleats)
When do we use fixed appliances?
- alignment of teeth
- correction of mild to moderate skeletal discrepancies
- corrections of rotations
- centreline correction
- overbite and overjet reduction
- closure and creating of space
- vertical movements of teeth
What materials can be used for the archwire?
SS , NiTi , CoCr, TMA (beta-titanium)
How does tooth movement work?
- when an external force is applied to a tooth , movements occur due to bone remodelling mediated by the PDL
- Orthodontic appliances transmit forces to PDL and bone resulting in osteoclast and osteoblast activity leading to tooth movement
cementum more reistant to resorption than bone
What are the three theories of orthodontic tooth movement?
- differential pressure theory
- piezo- electric
- mechano-chemical theory
Describe the Piezo electric theory of movement ?
- piezo electric current generated when bone is deformed
- which cause movement
- these currents are short lived and very small so unlikely to play a big role in remodelling
Briefly describe the differential pressure theory of tooth movement
- when force is applied to a tooth , bone is resorbed on the compression side and deposited on the tension side
Compression = resorption
Tension = deposition
Briefly Describe the mechanochemical theory
Mechanical loading causes stretching and compression of fibres within the PDL such as
* osteoblasts - produce prostaglandins and leukotrienes
* fibroblasts - matrix metalloproteinases ( breakdown extracellular matrix)
* macrophages - increase production of IL-1
causing bone resorption
Give an example of a cell interaction within the PDL that may cause tooth movement
- Cytokines activate osteoblasts to produce prostoglangins and leukotrienes
- This cause osteoblasts to produce an intracellular messenger
- Which initiates the production of RANKL and colony stimulating factors such IL-1 and CSF
- This activates osteoclasts and resorb the bone
What does RANKL do?
*Both RANKL and CSF cause blood monocytes to fuse and form osteoclasts
* RANKL stimulate the osteoclast to become active and resorb bone
* IL-1 increases the production of RANKL
How is bone resorption controlled?
- by osteoblasts , they produce RANKL which activate osteoclasts and OPG which suppresses osteoclast activity
- the balance between OPG and RANKL regulates bone remodelling
What is frontal resorption?
- In frontal resorption, bone is removed from the surface directly adjacent to the force applied (remodelling of socket)
- whereas, in undermining resorption, remodelling occurs from surfaces further away from the applied force
Give 4 methods of anchorage?
- Transpalatal arch
- Temorary anchorage devices that are non-osseointegrating screws
- Nance palatal arch - utilises palatal vault for anchorage reinforcement
- Elastomerics
What are the types of anchorage (6)
- Simple - using teeth of different sizes so the smaller moves towards the bigger
- Compound - using more than one tooth to move a smaller tooth
- Reciprocal - using similar teeth to achieve equal tooth movement
- Cortical - maintain intermolar width
- Absolute - TAD’s - forces distribute to cortical bone
- Inter-maxillary - using elastomerics
What is an overjet?
- the extent of horizontal overlap between the maxillary central incisors over the mandibular central incisors - in AP position
- average 2-4mm
How is overjet measured?
Using ruler held parallel to occlusal plane when teeth in ICP
What is an overbite?
- It is the extent of vertical overlap between the maxillary and mandibular incisors
- average 1/2 to 1/3
- can be average, increased or decreased
How is the molar relationship measured?
- Using the buccal segment of 6s relationship
- Class I - mesiobuccal cusp of upper molar occludes with mesiobuccal groove of lower 6
How is the canine relationship measured?
- using the buccal segment of the canines
- Upper canine occludes with embrasure between the lower canine and lower first premolar
How is crowding measured?
- space available vs space required
- using overlap technique
- mixed dentition analysis
What are the types of crowding/spacing ?
Mild - less than 4mm
Moderate - 4-8mm
Severe - more than 8mm
How is incisor angulation measured?
- using lateral cephalometry
Upper 109
lower 93
Why might a first molar be impacted in a 7 year old child?
- Eruption angle
- Ectopic cyst
- Small maxilla - not enough space
- Morphology of E crown
What problems are associated with impacted first molar that can be related to the E ?
- Pulpitis of E
- Premature exfoliation of E
- May cause pain and discomfort
Possible treatment options for an impacted first permanent molar?
- Observe for 6 months - usually will Disimpact on its own (66% at age 7)
- XLA of E - gain space for premolar or treat crowding later
- Dis-impaction by
Dicising distal crown of E
Seperators
URA with finger spring and attachment to 6 to push it back
Band the E and bracket the 6 with open coil
