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Orthodontics Flashcards

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1
Q

List any 3 uses of a URA apart from tipping and tilting teeth

A

* Habit breaker

* Space maintainer

* Reduce overbite (FABP)

* Retainer

* Dont say maxillary expansion as technically this does tip and tilt teeth

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2
Q

What is the patients malocclusion type, skeletal pattern and incisal relationship?

A

Class II division I

Class II skeletal base (moderate)

Class II division I incisors.

Retrognathic mandible.

High FMPA

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4
Q

In general, what are the possible aetiological factors Class II division I malocclusion?

A

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

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5
Q

In addition to having an OPT, what other ways (clinical and radiographic), can be used to assess the position of an unerupted canine?

A

* 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

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6
Q

What is the risk of providing no treatment in a patient with an IOTN of 5a?

A

* 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

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7
Q

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?

A

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.

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8
Q

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

A

* 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

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9
Q

Besides a URA what other type of space maintainer could be used?

A

* Fixed palatal arch

* Fixed palatal arch with nance button

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10
Q

How would you gauge if a patient has been wearing their appliance as instructed?

A

* 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

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11
Q

What are the eruption dates of the primary dentition?

A

A 6-7 mon

B 7-8 mon

C 18-20 mon

D 12-15 mon

E 24-36 mon

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12
Q

What are the eruption dates of the permanent dentition?

A

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

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13
Q

At what age would you expect crown formation to be complete?

A

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

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14
Q

At what age does crown formation begin?

A

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

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15
Q

At what age would you expect root formation to be complete?

A

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

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16
Q

What is the DHC of the IOTN hierarchial scale?

A

MOCDO

Missing teeth

Overjet

Crossbite

Displacement of contact points

Overbites (inc open bite)

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17
Q

What are the 6 components of a DHC grade 5?

A

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

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18
Q

What are the 11 components of a DHC grade 4?

A

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

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19
Q

Name some general aetiological factors of malocclusion

A

* 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

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20
Q

What is the aetiology of skeletal variation?

A

Genetic and environmental factors. Strong hereditary component to shape of face and jaws. Possible environmental factors include masticatory muscles, mouth breathing, head posture

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21
Q

What are the aetiological factors of class ii malocclusion

A

* 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

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22
Q

What are the aetiological factors of class iii malocclusion

A

* 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

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23
Q

What are some causes of facial asymmetries?

A

Dental cause; displacement of normal mandible due to unilateral crossbite.

True mandibular asymmetry; hemi-mandibular hyperplasia/elongation. Condylar hyperplasia

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24
Q

A patient has a 12mm OJ, well aligned arches and ectopic canines. What are the complications of these features?

A

Trauma risk.

Difficulty speaking

Difficulty eating

Psychological aspects

Root resorption of adjacent teeth

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25
Q

What are the dental complications of a retainer?

A

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.

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26
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
27
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
28
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
29
How could you assess a patients AP relationship?
Visually. Palpate skeletal bases. Lateral cephalometry
30
Name four intraoral features an adult patient with class iii occlusion may have
Reverse or reduced overjet. Displacement on closing. Retroclined lower teeth. Attition
31
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
32
What 5 factors can resist displacement forces?
Gravity. Active components. Tongue. Mastication. Speech
33
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.
34
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
35
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
36
What are the 3 types of supernumerary?
Mesiodens - conical. Tuberculate - malformed premolars Supplemental - extra teeth of normal morphology. Typically erups in correct position.
37
What is the aetiology of palatally ectopic canines?
Small laterals or small roots. Missing laterals. Typically class ii div ii
38
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
39
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.
40
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)
41
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
42
What are the consequences of extracting 6s of poor prognosis too early or too late?
Too early can result in distal tipping of 5s Too late can result in not enough mesial movement of 7s and space not closing
43
What is the purpose of a balancing extraction?
Preserves symmetry and prevents centre line shift. Involves extracting contra-lateral tooth in same arch
44
What is the purpose of a compensating extraction?
Allows molar teeth to drift in unison and prevent over eruption. Involves removing opposing tooth.
45
What is the aetiology and points of note of infraoccluding E's?
\* Strong genetic components \* Below the occlusal plane \* Early marker for dental abnormalities eg ectopic canines, hypodontia. \* Aplastic successor; slow root resorption leading to lack of exfoliation esp 12-13 years
46
What are the treatment options for infraoccluded E's?
\* Ideally wait for exfoliation. Timing of exfoliation on other side will give a guide. \* Extract only if - Deep infraocclusion, tipping/tilting of adjacent teeth and space loss - No permanent successor and concerns for future treatment of infraocclusion. Refer to ortho for advice
47
How is the degree of infraocclusion graded?
\* Slight - occlusal surface approx 1mm below occlusal plane \* Moderate - occlusal plane approx at level of contact points of adjacent teeth \* Severe - occlusal plane below the contact points, potentially at gingival level and allowing tipping of the adjacent teeth
48
What information relevant to the provision of ortho care needs to be provided in a referarl?
Pt details; name, DOB, address Any radiographs or photographs Skeletal base Incisor classification GDP details
49
What advice would you give to an adult pt with decalcification regarding maintaining oral health long term?
Brush 2 x daily for 2-5 minutes Use the modified bass technique Spit don't rinse Duraphat 5,000ppmF toothpaste Interdental cleaning Use disclosing tablets
50
What are some uses of a URA?
Tooth tipping/tilting Habit breaker Space maintainer Reduce overbite Expand arch Retainer
51
Give 6 pieces of advice on fitting a removable appliance
Wear the appliance 24/7 There will be some pain/discomfort, painkillers can be taken You will produce some excess saliva but this will improve with time/use You will have some difficulties with speech, this will improve with time/use Brush with toothbrush and warm soapy water every day Rinse after meals Store in storage box, NOT tissue during contact sports Avoid fizzy drinks and sticky foods Avoid very hot foods/drinks Give emergency contact details
52
Outline the delivery of a URA
Check correct patient and appliance Check appliance matches design Feel for any sharp edges Check integrity of wire work Insert and check for blanching of tissues/trauma Inspect posterior retention - flyover then arrowheads Check anterior retention Activate Show patient insertion and removal and have them demonstrate Review in 4-6 weeks
53
What is the incidence of hypodontia in the UK?
6% in permanent dentition 1-2% in primary dentition
54
What 3 teeth in order (excluding 8s) are most commonly missing?
Mandibular 5s Maxillary 2s Maxillary 5s
55
How might hypodontia present to you as a GDP?
Delayed/asymmetric eruption Infraocclusion Missing primary tooth Ectopic canine Cleft lip and palate
56
What are the options for treating hypodontia?
Accept and monitor Restorative options; Denture, implant, adhesive bridge Orthodontics alone Combination of ortho and restorative
57
Name four members of the multidisciplinary team
Paediatric dentist Orthodontist GDP Prosthodontist Speech and language therapist Restorative dentist Oral surgeon Clinical psychologist
58
At what age should you intervene with ectopic canines?
Age 11
59
What are the treatment options for an impacted 3 when the Cs have already been extracted?
Open exposure palatally +/- bone removal Open buccal, apically repositioned flap +/- bone removal Closed exposure and gold chain Surgical extraction of 3
60
What is a supernumary?
A tooth that is in addition to the normal dentition
61
62
What are the four causes of fracture of a stainless steel wire?
\*overworking \*mechanical abraision \*fatigue \*weld decay
63
What causes a stainless steel wire to become overworked?
The wire has been excessively overworked by bending and then straightening the wire at the same point creating extreme stresses within the immediate area which can result in fracture
64
What causes mechanical abraision of a stainless steel wire?
This can occur if the wire has been damaged by burs or stones in the finishing process of removable appliances or if the wire has been marked or crushed during the fabrication of components.
65
What are the causes of fatigue in a stainless steel wire?
This can be caused by a repeated straining action eg continually strained to engage a deep undercut with an Adams clasp
66
What causes weld decay in a stainless steel wire?
This is an intergranular corrosion created by overheating the alloy. This causes the chromium carbides to precipitate at the grain boundaries. The oral fluids can now access the surface of the other metals resulting in a galvanic action which weakens the area sufficiently to result in fracture
67
When writing a lab prescription for an orthodontic appliance, in what order should you make your requests?
\*Aim \*Active components \*Retention \*Anchorage \*Baseplate
68
Define retention
Retention is the resistance to displacement forces. ie the tongue, mastication, gravity, talking, active components (applied forces can cause displacement)
69
Define anchorage
resistance to unwanted tooth movement
70
List four supernumary teeth
\*conical \*tuberculate \*supplimental \*odontome
71
How can a crossbite be corrected?
A URA with a palatal midline screw
72
how often should a palatal midline screw be activated?
one per month
73
list 6 things that can go wrong with the growth and development of teeth
\*increased over jet \*anterior/posterior cross bite \*retained deciduous teeth \*ectopic teeth \*crowding \*trauma \*anterior/lateral open bites \*ankylosis of deciduous teeth \*diastema \*dental asymmetries \*deep overbit \*early loss of deciduous teeth \*impacted first molars \*spacing \*habits \*cysts \*supernummaries
74
Name five potential risks of orthodontic treatment
\*decalcification \*relapse \*root resorption \*pain/discomfort \*soft tissue trauma \*failure to complete treatment \*loss of tooth vitality \*inhale or swallow small components \*candidal infections
75
When should an orthodontic exam be carried out?
\*brief exam at around aged 9 \*comprehensive exam when premolars and canines erupt (11-12 years) \*when older patients first present \*if a malocclusion develops later in life
76
What are Andrews 6 keys?
i) Molar relationship; the distal surface of the disto-buccal cusp of the upper first permanent molar occludes with the mesial surface of the mesio-buccal cusp of the lower second permanent molar ii) crown angulation iii) crown inclination iv) no rotations v) no spaces vi) flat occlusal planes (no curve of spee)
78
Give the Britisd standards institute classification of incisor relationships
\*Class I - the lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors \*Class II - the lower incisor edges lie posterior to the cingulum plateau of the upper incisors - Division I; the upper incisors are proclined or are of average inclination and there is an INCREASE IN OVERJET - Division II; the UPPER CENTRAL INCISORS ARE RETROCLINED. The OJ is usually minimal or may be increased \*Class III - lower incisor edges lie anterior to the cingulum plateau of the upper incisors. The OJ is reduced or reversed
79
Describe FMPA
Frankfort mandibular plane angle; and angle created between teh frankfort horizontal plane and the lower border of the mandible. An increased FMPA if theres a premature meeting point A decreased FMPA if theres a delayed meeting point (should be at the back of the head)
81
What special investigations should be carried out as part of an orthodontic assessment?
\*radiographs (OPT, maxillary anterior occlusal, lateral cephalogram) \*vitality tests \*study models \*photographs
82
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
83
Dento-alveolar compensation
inclination of the teeth to compensate for underlying skeletal abnormalities
84
Describe the AP class I relationship
maxilla 2-3mm in front of mandible
85
Describe the AP class II relationship
maxilla \>3mm in front of mandible
86
Describe the AP class III relationship
mandible in front of maxilla
87
What is an increased FMPA?
Frankfort mandibular plane angle increased if premature meeting point
88
What is a decreased FMPA?
Frankfort mandibular plane angle decreased if delayed meeting point
89
Where is the ideal meeting point of the FMPA?
external occipital protuberance
90
What are the occlusal features of a sucking habit?
\*Proclination of upper anteriors \*Retroclination of the lower anteriors \*Localised AOB or incomplete over bite \*Narrow upper arch
91
What are the average values in class I cephalometrics?
\*SNA relates maxilla to anterior cranial base Average value 81o +/- 3o \*SNB relates mandible to anterior cranial base Average value 78o +/- 3o \*ANB relates mandible to maxilla Average value 3o +/- 2o
92
What is the average value of FMPA
27o +/- 4o
93
In terms of cephalometrics, what is the upper and lower anterior face height?
\*Upper; nasion to anterior nasal spine \*Lower; anterior nasal spine to menton \*average value of LAFH to TAFH 55%
94
What is a dental cause of facial asymmetry?
displacement of normal mandible due to unilateral crossbite
95
What is a true mandibular cause of facial asymmetry?
\*Hemi mandibular hypoplasia \*condylar hypoplasia
96
What are the four aetiologies of malocclusion?
\*skeletal (ie class III) \*dental (missing teeth) \*soft tissue (lip trap) \*habit (thumb sucking)
97
What are five local causes of malocclusion?
\*variation in tooth number \*variation in tooth size or form \*abnormalities of tooth position \*local abnormalities of soft tissues \*local pathology
98
Describe balancing extraction
by extraction of a tooth from the opposite side of the same arch. Designed to minimise midline shift.
99
Describe compensating extraction
by extraction of a tooth from the opposing arch of the same side. Designed to maintain occlusal relationship
100
What are the six types of tooth movement and their ideal force?
\*Tipping (35-60g) \*Bodily movement (150-200g) \*Intrusion (10-20g) \*extrusion (35-60g) \*rotation (35-60g) \*torgue (50-100g)
101
What methods are there of clinically assessing ectopic canines?
\*visualisation, palpation of any obvious bumps \*Inclination of 2(s) \*Mobility of c(s) or 2(s) \*colour of c(s) or 2(s) \*radiographic assessment (usually OPT and anterior occlusal (parallax technique)) \*3p's; presence, position, pathology
102
What is the physiological basis of orthodontics?
If an external force is applied to a tooth, the tooth will move as the bone around it remodels. This bony remodelling is mediated by the PDL.
104
What is interceptive orthodontics?
Any procedure that will reduce or eliminate the severity of developing malocclusion
105
What are the causes of unerupted central incisors?
Supernumeraries preventing eruption. Trauma/dilaceration

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