Orthodontics Flashcards
1
Q
What should be included in an orthodontic diagnosis?
A
Description of the malocclusion
Causes of the malocclusion (if applicable)
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
3
Q
What special test is required if suspected skeletal problem causing malocclusion?
A
Lateral cephalogram
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
5
Q
3 desired properties when undergoing ortho
A
Stable
Functional
Aesthetic
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
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
8
Q
Stages of treatment planning
A
- Plan around the lower arch (angulation of lower labial segment)
- Decide on treatment in lower
- Build upper arch around lower, aim for class I incisor and canine relationship (OJ and OB normal)
- Decide on molar relationship (class I or full unit class II)
9
Q
Checklist for examination of lower arch
A
Crowding/angulation of incisors
Angulation of the canines
Curve of spee
Centrelines
10
Q
Examination of upper arch checklist
A
Crowding/angulation of incisors
Angulation of canines
Centrelines
11
Q
Examination of teeth in occlusion checklist
A
Incisor relationship
OJ
OB
Centrelines
Canine relationship
Molar relationship
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
13
Q
What is mild/moderate/severe crowding?
A
Mild - 0-4mm
Moderate - 4-8mm
Severe - 8+mm
14
Q
Treatment options for mild crowding of lower arch
A
Stripping - metal sand paper remove some interproximal enamel
Extract 5s
15
Q
Treatment options for moderate crowding of lower arch
A
Extract 5s
Extract 4s
16
Q
Treatment options for severe crowding of lower arch
A
Ext 4s
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
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
19
Q
Treatment options for ortho patients
A
- Accept malocclusion - tell patient consequences of this
- Extractions only - occasionally, class I crowding cases, ext 4s
- URA - limited, good at reducing OB
- Functional appliance - largely for class II
- Fixed appliance - detailed movement, close spaces
- Complex treatment involving orthodontics and restorative treatment or orthodontics and orthognathic surgery
(3,4,5 can be done with or without extractions)
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
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
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)
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
24
Q
Class I skeletal relationship
A
Mandible 2-3mm behind maxilla
25
Class II skeletal relationship
>3mm mandible behind maxilla
26
Class III skeletal relationship
Mandible <2mm behind the maxilla
27
How is skeletal class judged by looking?
Looking side on with frankfort plane parallel to the floor, compare the position of the innermost curvatures of the two lips
28
Mandibular hypoplasia
Mandible is too small causes class II
29
Mandibular retrognathia
Mandible too far back causes class II
30
Mandibular prognathism
Mandible too big causes class III
31
Maxillary hypoplasia
Maxilla too small causes class III
32
Hemimandibular hypertrophy
Skeletal asymmetry
One side of the mandible continues to grow
33
Hemifacial microsomia
Failure in development of condyle, ramus and body of mandible on one side, to varying degree
Progressive facial asymmetry
Occlusal problems
Malformed ear
34
How to get a patient to position themself with Frankfort plane parallel to the floor
Look into their eyes in a mirror about 3 feet away
35
Treatment for skeletal discrepancies in growing patient
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)
36
Examination checklist for ortho diagnosis
Skeletal relationship (how the jaws relate to each other, and to the skull base)
Facial anomalies/asymmetry
Teeth in each arch
Occlusion
37
Further investigations that can be used in ortho diagnosis
Study models
Radiographs
Photographs
Sensibility tests
Cone beam CT
38
Aims of orthodontic treatment
Stable functional and aesthetic occlusion
39
Removeable appliances uses
Tip teeth, open bites, maintain space
40
Functional appliance mode of action
Modify jaw growth
41
Risks of orthodontic treatment
Decalcification
Relapse
Root resorption
Pain
Soft tissue trauma
Failure to complete treatment
Loss of treatment vitality
Aspiration/swallowing of small componenets
Candidal infections
42
When is orthodontic assessment done?
Brief examination at age 9
Comprehensive exam when premolars and canines erupt (11-12)
When older patients first present
If malocclusion develops
43
Ideal occlusion
Hypothetical, rarely found in nature
Gold standard by which occlusal irregularities and treatment may be judged
44
Andrews 6 keys
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
45
Malocclusion
Significant deviations from the ideal that may be considered unsatisfactory (aesthetically or functionally)
May require treatment, patient factors may influence the decision
46
Contra-indications for ortho treatment
Allergy (Ni or latex)
Epilepsy/drugs
Drugs
Imaging
47
Extra oral orthodontic exam
Skeletal bases (in antero-posterior, vertical and transverse planes)
Soft tissue
TMJ
48
Skeletal Class I
Maxilla 2-3mm in front of mandible
49
Skeletal Class II
Maxilla more than 3mm in front of mandible
50
Skeletal Class III
Mandible in front of maxilla
51
FMPA
Frankfort mandibular plane angle
52
How do soft tissues affect too position?
Lips - competent/incompetent, lower lip level and activity
Tongue - position, habitual, swallowing
Habits - thumb/digit sucking
Speech - lisping
53
Incompetent lips
Do not meet at rest with a relaxed mentalis muscle
54
Lip trap
Lower lip traps behind upper incisors
May procline upper incisors
May lead to relapse of overjet if persists after treatment
55
Strap lip
Hyperactive lower lip
May retrocline lower incisors
Indicates instability at end of treatment
56
What occlusal issue is associated with tongue thrust on swallowing?
AOB
May cause relapse after treatment
57
Occlusal effects of digit sucking habit
Proclined upper anteriors
Retroclined lower anteriors
Localised AOB or complete OB
Narrow upper arch +/- unilateral posterior crossbite
58
What should be examined in TMJ exam?
Path of closure
Range of movement
Click
Deviation on opening
Muscle tenderness
Pain
Mandibular displacement from RCP to ICP
59
Degree of crowding
Uncrowded
Mild
Moderate
Severe
60
Class I incisor relationship
The lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors
61
Class II incisor relationship
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
Class III incisal relationship
The lower incisor edges lie anterior to the cingulum plateau of the upper incisors. OJ if reduced or reversed
63
Average overbite
Upper incisor covers 1/2 to 1/3 of the lower incisor crown
64
Overbite types
Average
Increased
AOB
Increased and complete contacts tooth
Increased and complete contacts palate
Increased but incomplete
65
Canine relationship
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
Class I molar relationship
Mesiobuccal cusp of first upper molar contacts buccal groove of first lower molar
67
Class II molar relationship
Mesiobuccal cusp of first lower molar contacts buccal groove of first upper molar
68
Class III molar relationship
Second upper premolar contacts buccal groove of first lower molar
69
What should be included in an orthodontic summary?
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
3 views of relationship of skeletal bases
Antero-posterior
Vertical
Transverse
71
Most common cause of class II skeletal jaw relationship
Retrognathic mandible
72
Most common cause of class III skeletal relationship
Anteroposterior maxillary deficiency
73
Features of long face syndrome
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
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 true asymmetry of the mandible with the chin point shifted to the left
75
What is the term used to describe a mismatch between the size of the teeth and jaws?
Dento-alveolar disproportion
76
Frankfort plane
Lower orbital rim to superior border of EAM
77
Mandibular plane
Lower border of the mandible
78
Where do Frankfort plane and mandibular plane lines usually meet?
Occipital protuberance
79
Upper anterior face height
Glabella to base of nose
80
Lower anterior face height
Base of nose to inferior aspect of the chin
81
Average LAFH to TAFH
50%
82
Average FMPA
27 degrees (+/-4)
83
Characteristics of short facial type
FMPA < 23 degrees
LAFH to TAFH <55%
Tendency to parallelism of jaws
Forward mandibular growth rotation
Deep OB tendency
84
When does mandibular displacement occur?
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
What does disproportion between the arches cause?
Unilateral or bilateral buccal segment crossbites
86
Causes of facial asymmetry
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
Dento alveolar disproportion
Discrepancy between size of teeth and jaws
88
Local causes of malocclusion
Localised problem or abnormality within either arch, usually confined to one, two or several teeth producing a malocclusion
89
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
90
Variation in tooth number
Supernumerary teeth
Hypodontia
Retained primary teeth
Early loss of primary teeth
Unscheduled loss of permanent teeth
91
Supernumerary teeth
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
Types of supernumerary teeth
Tuberculate
Odontome
Supplemental
Conical
93
Conical supernumerary
Small peg shaped
Close to midline
May erupt (extract)
Usually 1 or 2
Tend not to prevent eruption but may displace adjacent teeth
94
Tuberculate supernumerary
Tend not to erupt
Paired
Barrel shaped
Usually extract
One of the main causes of failure of eruption of permanent upper incisors
95
Supplementary supernumerary
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
Odontome supernumerary
Compound - discreet denticles
Complex - disorganised mass of dentine, pulp, enamel
97
Hypodontia
Developmental absence of one or more teeth
Females>males
4-6% population (not including 8s)
Commonly upper laterals, second premolars
98
When should you consider that retention of primary teeth is unusual?
More than 6 months since shedding of contra lateral
99
Why are primary teeth retained?
Absence of successor
Ectopic or dilacerated successor
Infre-occluded (ankylosed) primary molars
Dentally delayed development
Pathology/suprenumerary
100
Management of primary tooth retention due to absence of successor
Maintain primary for as long as possible if good prognosis
Extract early to encourage spontaneous space closure in crowded cases
101
Causes of early loss of primary teeth
Trauma
PA pathology
Caries
Resorption by successor
102
Balancing extraction
Extraction of a tooth from the opposite side of the same arch
103
Compensation extraction
Extraction of a tooth from the opposing arch of the same side
104
Effects of early loss of primary teeth
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
Problems with macrodontia
Crowding
Asymmetry
Aesthetics
106
Abnormal form examples
Peg laterals
Dens in dente
Geminated/fused
Talon cusps
Dilaceration
Accessory cusps and ridges
107
Most commonly ectopic teeth
Third molars
Upper canines
First permanent molars
Upper centrals
108
From what age should a palpable buccal canine bulge be felt for?
9y
109
Indications of ectopic canines
Any obvious bumps around c
Inclination of 2
Mobility of c or 2
Colour of c or 2
110
Management options for ectopic upper 3
Prevent - extract c to encourage improvement of position
Retain and observe (accept its position)
Surgical exposure and orthodontic alignment
Surgical extraction
Autotransplantation
111
What mediates bone remodelling during ortho treatment
PDL?
112
Differential pressure theory
In areas of compression bone is resorbed and in areas of tension bone is deposited
113
Types of tooth movement
Tipping 35-60g
Bodily movement - 150-200g
Intrusion 10-20g
Extrusion 35-60g
Rotation 35-60g
Torque 50-100g
114
Mode of action of functional appliances
Skeletal change 30% dentoalveolar change 70%
Mesial migration of lowers + distal migration of uppers achieves a class I
115
Secondary remodelling
Allows tooth to retain normal periodontal ligament width and stability
116
What occurs on the pressure side during orthodontic treatment under light force?
Hyperaemia of blood vessels
Increased osteoclastic activity, resorption of lamina dura
PDL reorganises
-> resorption
117
What occurs on the tension side during ortho treatment under light force?
Hyperaemia of blood vessels
Increased osteoblastic activity, deposition of osteoid
-> depostion
118
What occurs of the pressure side and tension side during ortho treatment under moderate force?
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
What is the difference in movement over time between light/moderate/heavy orthodontic forces?
Light allows for slow continuous movement
Moderate and heavy - rapid movement initially then 10-14 days with little movement while undermining resorption occurs
120
Unwanted side effects of excessive forces
Pain
Necrosis and undermining resorption
Root resorption
Anchorage loss
Possible loss of tooth vitality
121
Factors affecting the response to orthodontic force
Magnitude
Duration
Age
Anatomy
122
Ideal tooth movement/time for orthodontic treatment
1mm per month
123
Embryological origin of most of the face
Neural crest
124
When does ossification of the face and skull occur?
7-8 weeks in utero
125
Primary abnormality
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
Secondary abnormality
Interruption of the normal development of an organ that can be traced back to other influences such as infection, chemicals or trauma
127
Agenesia
Absence of an organ due to failed development during embryonic period
128
Sites of facial growth
Sutures
Synchrondroses
Surface deposition
129
Synchondroses
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
Deciduous dentition characteristics
More susceptible to wear
Incisors more upright
Spaced
131
Interceptive orthodontics
Any procedure that will reduce or eliminate the severity of a developing malocclusion
132
What size midline diastema is likely to close once 3s are fully erupted?
2.5mm
133
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?
One half to two thirds root formed
