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BDS3 > Orthodontics > Flashcards

Orthodontics Flashcards

1
Q

What should be included in an orthodontic diagnosis?

A

Description of the malocclusion
Causes of the malocclusion (if applicable)

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2
Q

Possible causes of malocclusion

A

Dentoalveolar or skeletal
Small teeth - spacing
Early loss of deciduous teeth - crowding
Digit sucking - proclination or increased OJ

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3
Q

What special test is required if suspected skeletal problem causing malocclusion?

A

Lateral cephalogram

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4
Q

Why is important to know whether the cause is skeletal?

A

Ortho can only modify skeletal relationship minimally
A severe surgical discrepancy may require surgical intervention

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5
Q

3 desired properties when undergoing ortho

A

Stable
Functional
Aesthetic

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6
Q

Potential factors influencing ortho treatment plan

A

Patient’s wishes
Access to treatment
Compliance
Space requirements
Aims of treatment
Prognosis of individual teeth
Future growth changes
Aetiology of malocclusion
Patient’s soft tissue profile
Retention
Stability

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7
Q

Desired occlusion to aim for

A

Class I incisor relationship (OJ/OB normal)
Class I canine relationship
Class I molar relationship (can accept class II)
No rotations, spaces, flat occlusal plane

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8
Q

Stages of treatment planning

A
  1. Plan around the lower arch (angulation of lower labial segment)
  2. Decide on treatment in lower
  3. Build upper arch around lower, aim for class I incisor and canine relationship (OJ and OB normal)
  4. Decide on molar relationship (class I or full unit class II)
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9
Q

Checklist for examination of lower arch

A

Crowding/angulation of incisors
Angulation of the canines
Curve of spee
Centrelines

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10
Q

Examination of upper arch checklist

A

Crowding/angulation of incisors
Angulation of canines
Centrelines

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11
Q

Examination of teeth in occlusion checklist

A

Incisor relationship
OJ
OB
Centrelines
Canine relationship
Molar relationship

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12
Q

How to assess whether extraction is required for crowding?

A

Measure space available and space required - overlap technique to estimate extent of crowding

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13
Q

What is mild/moderate/severe crowding?

A

Mild - 0-4mm
Moderate - 4-8mm
Severe - 8+mm

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14
Q

Treatment options for mild crowding of lower arch

A

Stripping - metal sand paper remove some interproximal enamel
Extract 5s

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15
Q

Treatment options for moderate crowding of lower arch

A

Extract 5s
Extract 4s

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16
Q

Treatment options for severe crowding of lower arch

A

Ext 4s

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17
Q

If extracting for crowding in the lower arch, what are the treatment options for the upper arch?

A

Must extract - MR class I

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18
Q

If you have no extracted in the lower arch, what are the treatment options in the upper arch?

A

Extract - MR class II
Distalise UBS using headgear - MR class I

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19
Q

Treatment options for ortho patients

A
  1. Accept malocclusion - tell patient consequences of this
  2. Extractions only - occasionally, class I crowding cases, ext 4s
  3. URA - limited, good at reducing OB
  4. Functional appliance - largely for class II
  5. Fixed appliance - detailed movement, close spaces
  6. Complex treatment involving orthodontics and restorative treatment or orthodontics and orthognathic surgery

(3,4,5 can be done with or without extractions)

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20
Q

Limitations of orthodontic treatment

A

Effects of orthodontic treatment are alsmot purely dento-alveolar and tooth movement, little skeletal influence
Tooth movements are limited by the shape and size of alveolar processes
Teeth will only remain stable in a position where there is equilibrium between the forces of the soft tissue, the occlusion and the periodontal structures. All other positions are unstable and prone to relapse

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21
Q

Who should carry out orthodontic treatment?

A

Simple treatment - GDP (relatively straightforward, can be managed with URA)
Complex treatment - specialist practitioner or hospital specialist

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22
Q

Why is timing of orthodontics important?

A

Some treatment relies on growth for success and should be used during the adolescent growth spurt for maximal effect (e.g. OB reduction, functional appliance therapy)

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23
Q

Orthodontics

A

Specialty of dentistry concerned with growth and development of teeth, face and jaws
Diagnosis, prevention and correction of dental and facial irregularities

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24
Q

Class I skeletal relationship

A

Mandible 2-3mm behind maxilla

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25
Q

Class II skeletal relationship

A

> 3mm mandible behind maxilla

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26
Q

Class III skeletal relationship

A

Mandible <2mm behind the maxilla

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27
Q

How is skeletal class judged by looking?

A

Looking side on with frankfort plane parallel to the floor, compare the position of the innermost curvatures of the two lips

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28
Q

Mandibular hypoplasia

A

Mandible is too small causes class II

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29
Q

Mandibular retrognathia

A

Mandible too far back causes class II

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30
Q

Mandibular prognathism

A

Mandible too big causes class III

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31
Q

Maxillary hypoplasia

A

Maxilla too small causes class III

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32
Q

Hemimandibular hypertrophy

A

Skeletal asymmetry
One side of the mandible continues to grow

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33
Q

Hemifacial microsomia

A

Failure in development of condyle, ramus and body of mandible on one side, to varying degree
Progressive facial asymmetry
Occlusal problems
Malformed ear

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34
Q

How to get a patient to position themself with Frankfort plane parallel to the floor

A

Look into their eyes in a mirror about 3 feet away

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35
Q

Treatment for skeletal discrepancies in growing patient

A

Growth modification techniques to promote or restrict growth of either jaw
Functional appliance - grow mandible
Headgear - Restrict maxillary growth
Reverse pull facemask and RME - promotes maxillary growth (age 8-10/11)

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36
Q

Examination checklist for ortho diagnosis

A

Skeletal relationship (how the jaws relate to each other, and to the skull base)
Facial anomalies/asymmetry
Teeth in each arch
Occlusion

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37
Q

Further investigations that can be used in ortho diagnosis

A

Study models
Radiographs
Photographs
Sensibility tests
Cone beam CT

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38
Q

Aims of orthodontic treatment

A

Stable functional and aesthetic occlusion

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39
Q

Removeable appliances uses

A

Tip teeth, open bites, maintain space

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40
Q

Functional appliance mode of action

A

Modify jaw growth

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41
Q

Risks of orthodontic treatment

A

Decalcification
Relapse
Root resorption
Pain
Soft tissue trauma
Failure to complete treatment
Loss of treatment vitality
Aspiration/swallowing of small componenets
Candidal infections

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42
Q

When is orthodontic assessment done?

A

Brief examination at age 9
Comprehensive exam when premolars and canines erupt (11-12)
When older patients first present
If malocclusion develops

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43
Q

Ideal occlusion

A

Hypothetical, rarely found in nature
Gold standard by which occlusal irregularities and treatment may be judged

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44
Q

Andrews 6 keys

A

Molar relationship - distal surface of 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
Crown angulation - mesio-distal tip
Crown inclination
No rotations
No spaces
Flat occlusal planes

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45
Q

Malocclusion

A

Significant deviations from the ideal that may be considered unsatisfactory (aesthetically or functionally)
May require treatment, patient factors may influence the decision

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46
Q

Contra-indications for ortho treatment

A

Allergy (Ni or latex)
Epilepsy/drugs
Drugs
Imaging

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47
Q

Extra oral orthodontic exam

A

Skeletal bases (in antero-posterior, vertical and transverse planes)
Soft tissue
TMJ

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48
Q

Skeletal Class I

A

Maxilla 2-3mm in front of mandible

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49
Q

Skeletal Class II

A

Maxilla more than 3mm in front of mandible

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50
Q

Skeletal Class III

A

Mandible in front of maxilla

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51
Q

FMPA

A

Frankfort mandibular plane angle

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52
Q

How do soft tissues affect too position?

A

Lips - competent/incompetent, lower lip level and activity
Tongue - position, habitual, swallowing
Habits - thumb/digit sucking
Speech - lisping

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53
Q

Incompetent lips

A

Do not meet at rest with a relaxed mentalis muscle

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54
Q

Lip trap

A

Lower lip traps behind upper incisors
May procline upper incisors
May lead to relapse of overjet if persists after treatment

55
Q

Strap lip

A

Hyperactive lower lip
May retrocline lower incisors
Indicates instability at end of treatment

56
Q

What occlusal issue is associated with tongue thrust on swallowing?

A

AOB
May cause relapse after treatment

57
Q

Occlusal effects of digit sucking habit

A

Proclined upper anteriors
Retroclined lower anteriors
Localised AOB or complete OB
Narrow upper arch +/- unilateral posterior crossbite

58
Q

What should be examined in TMJ exam?

A

Path of closure
Range of movement
Click
Deviation on opening
Muscle tenderness
Pain
Mandibular displacement from RCP to ICP

59
Q

Degree of crowding

A

Uncrowded
Mild
Moderate
Severe

60
Q

Class I incisor relationship

A

The lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors

61
Q

Class II incisor relationship

A

The lower incisor edges lie posterior to the cingulum plateau of the upper incisors
Div I - The upper incisors are proclined or of an average inclination and there is an increase in OJ
Div II - The upper central incisors are retroclined the OJ is minimal or decreased

62
Q

Class III incisal relationship

A

The lower incisor edges lie anterior to the cingulum plateau of the upper incisors. OJ if reduced or reversed

63
Q

Average overbite

A

Upper incisor covers 1/2 to 1/3 of the lower incisor crown

64
Q

Overbite types

A

Average
Increased
AOB
Increased and complete contacts tooth
Increased and complete contacts palate
Increased but incomplete

65
Q

Canine relationship

A

Class I - mandibular canine cusp tip anterior to maxillary canine cusp tip
Class II - cusp tips in line
Class III - Maxillary canine cusp tip anterior to mandibular

66
Q

Class I molar relationship

A

Mesiobuccal cusp of first upper molar contacts buccal groove of first lower molar

67
Q

Class II molar relationship

A

Mesiobuccal cusp of first lower molar contacts buccal groove of first upper molar

68
Q

Class III molar relationship

A

Second upper premolar contacts buccal groove of first lower molar

69
Q

What should be included in an orthodontic summary?

A

Name/age/sex of patient
HPC, RMH, RDH
Incisor relationship, skeletal relationship
Teeth present/absent
OH
Lower and upper arch incisor inclination, crowding
OJ, OB, centrelines, molar relationship, crossbites
IOTN score

70
Q

3 views of relationship of skeletal bases

A

Antero-posterior
Vertical
Transverse

71
Q

Most common cause of class II skeletal jaw relationship

A

Retrognathic mandible

72
Q

Most common cause of class III skeletal relationship

A

Anteroposterior maxillary deficiency

73
Q

Features of long face syndrome

A

Backward growth rotation of the mandible
Increased maxillary posterior dentoalveolar height
An increased lower anterior face height percentage (>55% of TAFH)
FMPA >31 degrees
Ante-gonial notching of the mandible
AOB tendency
Steeply inclined mandibular plane

74
Q

What is the likely cause of a left sided unilaterally posterior crossbite that is not associated with a lateral displacement of the mandible on closure?

A

A true asymmetry of the mandible with the chin point shifted to the left

75
Q

What is the term used to describe a mismatch between the size of the teeth and jaws?

A

Dento-alveolar disproportion

76
Q

Frankfort plane

A

Lower orbital rim to superior border of EAM

77
Q

Mandibular plane

A

Lower border of the mandible

78
Q

Where do Frankfort plane and mandibular plane lines usually meet?

A

Occipital protuberance

79
Q

Upper anterior face height

A

Glabella to base of nose

80
Q

Lower anterior face height

A

Base of nose to inferior aspect of the chin

81
Q

Average LAFH to TAFH

A

50%

82
Q

Average FMPA

A

27 degrees (+/-4)

83
Q

Characteristics of short facial type

A

FMPA < 23 degrees
LAFH to TAFH <55%
Tendency to parallelism of jaws
Forward mandibular growth rotation
Deep OB tendency

84
Q

When does mandibular displacement occur?

A

Where inter arch width discrepancy results in upper and lower posteriors occluding cusp to cusp - mandible forced to deviate to one side to achieve maximum intercuspation

85
Q

What does disproportion between the arches cause?

A

Unilateral or bilateral buccal segment crossbites

86
Q

Causes of facial asymmetry

A

Dental cause - displacement of normal mandible due to unilateral crossbite
True mandibular asymmetry - hemimandibular hyperplasia/elongation, condylar hyperplasia
Whole face may be affected by mild expressions of hemi-facial microsomia

87
Q

Dento alveolar disproportion

A

Discrepancy between size of teeth and jaws

88
Q

Local causes of malocclusion

A

Localised problem or abnormality within either arch, usually confined to one, two or several teeth producing a malocclusion

89
Q

Local causes of malocclusion

A

Variation in tooth number
Variation in tooth size or form
Abnormalities of tooth position
Local abnormalities of soft tissues
Local pathology

90
Q

Variation in tooth number

A

Supernumerary teeth
Hypodontia
Retained primary teeth
Early loss of primary teeth
Unscheduled loss of permanent teeth

91
Q

Supernumerary teeth

A

A tooth or tooth like entity additional to the normal series
Most common anterior maxilla
Males>females
~1% in primary dentition
~2% in permanent dentition

92
Q

Types of supernumerary teeth

A

Tuberculate
Odontome
Supplemental
Conical

93
Q

Conical supernumerary

A

Small peg shaped
Close to midline
May erupt (extract)
Usually 1 or 2
Tend not to prevent eruption but may displace adjacent teeth

94
Q

Tuberculate supernumerary

A

Tend not to erupt
Paired
Barrel shaped
Usually extract
One of the main causes of failure of eruption of permanent upper incisors

95
Q

Supplementary supernumerary

A

Extra teeth of normal morphology
Most often upper laterals or lower incisors
Can be third premolars, fourth molars
Often extract, based on form and position

96
Q

Odontome supernumerary

A

Compound - discreet denticles
Complex - disorganised mass of dentine, pulp, enamel

97
Q

Hypodontia

A

Developmental absence of one or more teeth
Females>males
4-6% population (not including 8s)
Commonly upper laterals, second premolars

98
Q

When should you consider that retention of primary teeth is unusual?

A

More than 6 months since shedding of contra lateral

99
Q

Why are primary teeth retained?

A

Absence of successor
Ectopic or dilacerated successor
Infre-occluded (ankylosed) primary molars
Dentally delayed development
Pathology/suprenumerary

100
Q

Management of primary tooth retention due to absence of successor

A

Maintain primary for as long as possible if good prognosis
Extract early to encourage spontaneous space closure in crowded cases

101
Q

Causes of early loss of primary teeth

A

Trauma
PA pathology
Caries
Resorption by successor

102
Q

Balancing extraction

A

Extraction of a tooth from the opposite side of the same arch

103
Q

Compensation extraction

A

Extraction of a tooth from the opposing arch of the same side

104
Q

Effects of early loss of primary teeth

A

Incisors - very little effect, no compensating/balancing
Canines - unilateral in crowded arch can shift centreline and some mesial drift of buccal segments, consider balancing extraction
Molars - More space loss E>D and upper>lower, 6s drift mesially taking 5 space

105
Q

Problems with macrodontia

A

Crowding
Asymmetry
Aesthetics

106
Q

Abnormal form examples

A

Peg laterals
Dens in dente
Geminated/fused
Talon cusps
Dilaceration
Accessory cusps and ridges

107
Q

Most commonly ectopic teeth

A

Third molars
Upper canines
First permanent molars
Upper centrals

108
Q

From what age should a palpable buccal canine bulge be felt for?

A

9y

109
Q

Indications of ectopic canines

A

Any obvious bumps around c
Inclination of 2
Mobility of c or 2
Colour of c or 2

110
Q

Management options for ectopic upper 3

A

Prevent - extract c to encourage improvement of position
Retain and observe (accept its position)
Surgical exposure and orthodontic alignment
Surgical extraction
Autotransplantation

111
Q

What mediates bone remodelling during ortho treatment

A

PDL?

112
Q

Differential pressure theory

A

In areas of compression bone is resorbed and in areas of tension bone is deposited

113
Q

Types of tooth movement

A

Tipping 35-60g
Bodily movement - 150-200g
Intrusion 10-20g
Extrusion 35-60g
Rotation 35-60g
Torque 50-100g

114
Q

Mode of action of functional appliances

A

Skeletal change 30% dentoalveolar change 70%
Mesial migration of lowers + distal migration of uppers achieves a class I

115
Q

Secondary remodelling

A

Allows tooth to retain normal periodontal ligament width and stability

116
Q

What occurs on the pressure side during orthodontic treatment under light force?

A

Hyperaemia of blood vessels
Increased osteoclastic activity, resorption of lamina dura
PDL reorganises
-> resorption

117
Q

What occurs on the tension side during ortho treatment under light force?

A

Hyperaemia of blood vessels
Increased osteoblastic activity, deposition of osteoid
-> depostion

118
Q

What occurs of the pressure side and tension side during ortho treatment under moderate force?

A

Occlusion of blood vessels
Cell free areas - hylinisation
Increased endosteal vascularity
Increased osteoclastic activity
Sudden movement

Tension - hyperaemia of BVs, period of stasis, healing of PDL

119
Q

What is the difference in movement over time between light/moderate/heavy orthodontic forces?

A

Light allows for slow continuous movement
Moderate and heavy - rapid movement initially then 10-14 days with little movement while undermining resorption occurs

120
Q

Unwanted side effects of excessive forces

A

Pain
Necrosis and undermining resorption
Root resorption
Anchorage loss
Possible loss of tooth vitality

121
Q

Factors affecting the response to orthodontic force

A

Magnitude
Duration
Age
Anatomy

122
Q

Ideal tooth movement/time for orthodontic treatment

A

1mm per month

123
Q

Embryological origin of most of the face

A

Neural crest

124
Q

When does ossification of the face and skull occur?

A

7-8 weeks in utero

125
Q

Primary abnormality

A

Defect in the structure of an organ or part of an organ that can be traced back to an anomaly in its development (Spina bifida, cleft lip)

126
Q

Secondary abnormality

A

Interruption of the normal development of an organ that can be traced back to other influences such as infection, chemicals or trauma

127
Q

Agenesia

A

Absence of an organ due to failed development during embryonic period

128
Q

Sites of facial growth

A

Sutures
Synchrondroses
Surface deposition

129
Q

Synchondroses

A

Found in the midline between the ethmoid, sphenoid and occipital bone
Cartilage based growth centre with growth occurring in both directions
New cartilage formed in centre, peripheral cartilage turns into bone

130
Q

Deciduous dentition characteristics

A

More susceptible to wear
Incisors more upright
Spaced

131
Q

Interceptive orthodontics

A

Any procedure that will reduce or eliminate the severity of a developing malocclusion

132
Q

What size midline diastema is likely to close once 3s are fully erupted?

A

2.5mm

133
Q

In order to promote eruption of upper second premolar, what is the ideal stage of root development of the unerupted tooth at which to extract the deciduous second molar?

A

One half to two thirds root formed

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