Potential Questions Flashcards
1
Q
What landmarks are used to construct the mandibular and Frankfort planes
A
- Po to Or
- Go to Me
2
Q
What angle is used to determine the anteroposterior position of the mandible
A
- ANB
3
Q
What angle is used to determine vertical discrepancies
A
- FMPA angle
4
Q
Name 3 salivary glands
A
- Parotid gland
- Submandibular gland
- Sublingual gland
5
Q
What are the uses of saliva
A
- chewing , lubrication, digestion,
6
Q
What are the implications of saliva during orthodontic procedure?
A
- cleaning, buffering PH level, prevent caries
- Disadvantage- Moisture control
7
Q
Name the muscles of mastication
A
- Masseter
- Medial pterygoid
- Lateral pterygoid
- Temporalis
8
Q
What muscle of mastication is used to open the mouth
A
- Lateral Pterygoid
9
Q
What nerve supplies muscle of mastication muscles ?
A
- 5th Trigeminal nerve
10
Q
Which of these muscles would ache when a functional appliance is worn
A
Masseter
11
Q
What are the effects on the dentition from a digit sucking habit
A
- Open bite - Unilateral: bilateral displacement
- Anterior open bite.
- Proclined upper incisor
- Retroclined lower incisors
- crossbite with mandibular displacement
12
Q
What are the factors in the amount of effects that may occur
A
Skeletal factor - Increased lower face height
Soft tissue - forward tongue posture or atypical swallowing pattern
Habit - digit sucking
Combination of above
13
Q
For a patient with a Class II div I type malocclusion, what makes trauma more likely
A
– 45% of 12 yrs old children with OJ > 9mm had visible damage to increased incisor
- More effect of OJ in females than males
- 50% children need tx following trauma.
14
Q
For a patient who has had previous trauma what might you consider during treatment planning
A
- No tx
- Explained risk of trauma before tx
- Involved pt and parent with decision
- Shorter treatment length / aim
- Monitoring during tx
- light conts force
15
Q
If a patient complained about you, what would you do.
A
- Acknowledge mistake and apologise.
- Listen carefully.
- Explain them what went wrong and put things right quickly and effectively.
16
Q
What are the effects of using too much force
A
- If excessive force is applied for prolonged period, the blood flow cut off from PDL and sterile necrosis ( hyalinisation) will result and no osteoclastic stimulation occurs. Bone will remodelled by cells from adjacent undamaged areas this is known as undermining resorption.
Results into : Pain for pt , Slow movement , Root resorption and Ankylosis.
17
Q
What factors must you consider before you change an arch wire
A
-Niti - alignment wire flexible shape memory and low constant force
- SS- Rigid, high stiffness, low friction than Niti.
Bodily movement - Niti/ SS rectangular wire 2 point contact
18
Q
What wire would you use for space closure
A
- SS round wires for sliding mechanism.
19
Q
What are the factors that decide the force in an aligning arch wire
A
- Below capillary pressure 20-25 gm/cm2
20
Q
What is friction and how would you limit it
A
- Friction is the force resisting relative motion.
Law- Friction = Force x Coefficient of Friction. - Bracket - material ceramic > friction than metal
- Wire- material - beta titanium > friction than NiTi > friction than SS
- Type of Ligation - Elastomeric ligatures 60-70% more than SS.
- ## Type of tooth movement - Tipping bodily movement
21
Q
What is informed consent
A
- A patient must be given full information about what treatment is involved including benefits,
Risks, advantages and disadvantages. Alternatives
to treatment including doing nothing.
22
Q
How should it be documented
A
- Contemporaneous
- Informed written consent.
- Signing a consent form with all option, benefit, advantages ,disadvantages given letting them know it’s inform decision.
23
Q
Name another form of consent
A
- Implied - Book and turn up for appointment
- Expressed - Either Verbal or writing express they are happy for appt to go ahead with treatment prescribed.
- Informed- Signing consent form with all options, risks, benefits, advantages and disadvantages given letting them know it’s an informed decision.
24
Q
List 3 helpful aids that could be used when explaining orthodontic treatment to patients
A
- Photos
- Study model / Digital scan
- Radiographs
- appliances
25
What should all dental staff be immunised against
- Tetnus
- Hep B
-Hep C
- Diptheria
- Polio
- MMR
26
How many hours of CPD does an orthodontic therapist have to complete
- 75 hours per cycle verifiable.
- Unlimited non verifiable.
27
What is CPD and why is it necessary
Continuing professional development is defined as learning experiences which help you develop and improve your professional practice.
28
What 5 things should be documented on an OPT
- Present teeth
-Position of teeth
- Pathology- Decay ,'bone level, length of root ,cyst , periodontal disease.
- Clinical Justification
-Optimisation
29
List 5 things shown on an OPT
- 3P- Position, presence and pathology of tooth
- Bone level
30
Why do we need retention
- Due to elastic recoil of gingival and PDL fibres.
- For reorganisation of the periodontal and gingival tissue after Orthodontic treatment.
- PDL reorganises over 3months
- Gingival (Collagenous fibres) reorganise over 6month
- Gingival (Supercrestal fibres) reorganise over 1 yr.
31
Name 2 periodontal fibres and how long it takes them to reorganise
- 3-6months - Supracrestal and collagenous periodontal and
- 1 year transseptal fibres
32
What would you do if you dropped etch:
On a patients lip
On a patients clothing
In a patients eye
- On lip - Wash, inform pt and apologise. record in notes and incident book. Explain scab can appear but it will heal. Suggest to contact pharmacist if needed. Follow up with pt .
- Patient clothing - remove it and inform pt and apologies.
- Patient eye- Wash immediately and rinse thoroughly. apologise and inform pt and orthodontist, record in accident book. Ask them to get it check asap.
33
What is the definition of relapse
Reasons for relapse
Types of retainers
- The Return , following correction of original features of malocclusion
- Orthodontic tooth movement results in disruption of periodontal and gingival structures. Because tissue are slow to remodel following orthodontic tooth movement, residual tension with periodontal ligament and gingival fibres results in elastic recoil which moves teeth towards their original position. 3-4 months PD, 4-6 months gingival fibres and 1 year transseptal fibres
- Hawley retainer , Vacuum formed essix retainer and Fixed bonded retainer.
34
What is iotrogenic damage
List 2 benefits of orthodontic treatment
List 3 risks of orthodontic treatment
- Tissue or organ damage that's caused by necessary medical treatment
- Improves OH , Aesthetic, and function
- Root resorption, relapse , decalcification.
35
What causes a splinter haemorrhage
Who would you consult with regarding this
What should healthcare workers be vaccinated against
Name 2 blood borne viruses
What virus could you catch with an ungloved hand
What is the most common metal allergy.
- Bacteria endocarditis and scleroderma
- GP
- Tetnus, Polio, diptheria, MMR (Measles,mumps and Rubella).
- Hepatitis B, Hepatitis C, HIV.
- Hep B, Hep C?
- Nickel
36
What are the 3 fibres contributing to ortho relapse
How long does it take for the elastic fibres to remodel
What effect do 3rd molars have on stability
What 3 factors are important in stability
- Periodontal fibre , Gingival fibre and Transseptal fibre.
- Periodontal fibre 3-4 months, (Collagenous fibre ) 4-6 months and (Supercrestal fibres)Transseptal fibre 1 year
- No outcome. Some says cause mandibular anterior crowding occurs
- Periodontium, soft tissue, growth and occlusion.
37
What causes an open bite
What treatment would you advise
1 - High FMPA angle ,backward growth rotation
- Habit- Tongue thrust
- aitrogenic - Extrusion of molars
- Trauma- effecting condyle
- Pathology- CLP
- Respiration
2- Stop habit , Orthodontic approach, Orthognathic approach or both
38
Define anchorage
List 3 ways to increase anchorage in a fixed appliance system
What happens if excessive force is applied
How long does force need to be applied before movement
When headgear is used for anchorage what is the force and duration
- Resistance of unwanted tooth movement.
- Increased number of teeth to anchor unit by increasing root surface area. Restrict anchor unit to move and maximise wanted tooth movement and minimise unwanted tooth movement.
-If excessive force is applied direct resorption of the bone doesn’t occur due to compression of blood vessels, ground glass appearance hyalinisation occurs Sterile necrosis. Indirect root resorption (undermining root resorption) occurs once pressure is released.
- Light constant force for more than 6hours
- Anchorage 250-300g per side 10-12 hours
39
What is meant by ‘Duty of Care’
What is informed consent
Who can give consent for a pt under the age of 16
Who can give consent to a handicapped pt over the age of 16
How long are we legally required to keep pt records
- be honest and open to patient if something goes wrong
- informed consent means patient and parent has been informed verbally and written about all tx options, benefits and risk included including no tx option.
- anyone who is under age of 16 has mental capacity to understand information and take decision.
- parent or legal guardian
- Till age of 25 and 11 years
40
What is the risk of inducing cancer when taking a ceph
What is the effective dose of an OPT
What information can be obtained from a ceph
Name the usual planes drawn on a ceph tracing and what landmarks are needed to do so
- risk is very less but unnecessary radiation from diagnostic Radiographs cause 200-250 uk cancer fatalities. 25% of all X-rays are dental examination xray.
- -< 3 uSv Sievert Ceph
- It is reproducible radiographs of lateral Skull to assess facial, dental and skeletal relationship in vertical and anterior posterior dimensions.
- Frankfort plane - Or-Po
- Sn plane - Sella to Nasion
- Maxillary plane - Ans -
Mandibular plane - Go- Me
41
Name the 4 components of a URA
What type of movement can be obtained with a URA
What functional appliance allows eruption of the buccal segments
Name 2 ways of transitioning from a functional to FA
What muscles are utilised during functional therapy
What proportion of the effects are dental and skeletal
ARAB- Active - anterior / posterior bite plane Spring 0.5mm (Retentive - Southend 0.8mm Elgiloy 0.7mm ss , Labial bow 0.7mm Adams's 0.6 mm crib Anchorage - palatal vault, root surface area, extra oral. Base plate- Completed,segmented ,buccal capping.
- Tip teeth around fulcrum at centre of resistance.
- bite planes ?
- Trimming / undermining blocks.
- A period of nights only wear after overjet reduction - usually 3 months
- When overjet reduced, place URA with very steep anterior bite plane to reduce overbite and hold mandible and lower incisor forward.
- Subsequent fixed appliances
- Muscle of mastication
- facial muscles
- Oro facial
- 70% dental 30% skeletal
42
Describe a Class I molar relationship
Name 2 common presenting features of a Class I malocclusion
Describe a Class II div I incisor relationship
What is the aetiology of a Class II div I malocclusion
Nmae Andrews 6 keys
- Crowding and Bimaxillary proclination
- Sk Class 2 relationship, Habit - Thumb sucking, Soft tissue- Lower lip trap behind upper incisors,short upper lip.
- Correction of molar relationship, correction of inclination of teeth, correction of angulation of teeth, flat curve of spee, no rotation, no space.
43
What is COSHH
What are the 7 steps of hazardous substances
- The Control of Substances Hazardous to Health.
- - Conduct a COSHH risk assessment
- Eliminate any risks
- Implement control measures
- Review control measures
- Develop emergency procedures
- Monitor workplace exposure levels
- Conduct health surveillance
-Provide information and training
44
Give 3 examples of the effects of hazardous substances
What would you do if you dropped etch on a pts lip
- Irritant, Skin damage and dizziness
- inform pt duty of candour. Be apologetic by mean, explain what can happen and how to manage it and follow up with it, document Contemporaneous notes and incident book.
45
Name 5 ways to isolate for a bond up
What type of etch is used
What 4 things does etch do
- Cheeck retractors, suction, cotton rolls, dry guard, saliva ejector.
- Phosphoric acid 20-35% apply for 15-30 seconds.
- to Increase surface area for bonding by increasing surface area.
46
What chemical is unfilled resin
Why is resin used
What does the light do
Q-List the advantages and disadvantages of direct and indirect bonding
Q-What is the difference between the 2
- Methyl methacrylate monomer
- To protect etched surface
- Polymerisation- the process of converting a liquid monomer or prepolymer into a solid polymer by a polymerization reaction when irradiated by UV or visible light
-
-
47
What is meant by intra arch and gives examples
What is meant by inter arch and give examples
- Intra arch- Same arch - Rotation, space, crowding of teeth.
- Inter arch- both arch - increased or decreased Overjet, increased or decreased overbite cross , scissor bite.
48
Where should a bracket be placed
What does a SWA provide
Where should a buccal tube be placed
What is the molar relationship if:
Upper first premolars have been extracted
Lower first pre molars have been extracted
All first premolars have been extracted
No premolars have been extracted
- LA point of LACC precise position.
- SWA- single wire appliance provide 3 order movement build in bracket.
- Buccal tube should be placed on Buccal midpoint of molar.
- Upper premolars- Class 2
Lower premolars- class 3
-All 4- Class 1.
- No Xtn. Class 1
49
List 3 ways of treating a skeletal problem
Q-What might happen to lip support if dental camouflage is used
What are the dental changes produced in functional therapy
- Orthdontics alone , Orthognathic alone or both.
- - incompetent lip may result relapse of tx like corrected overjet increased
- Proclined lower incisors
Retroclined upper incisors
Mesial movement of lower buccal segment
Distal movement of upper buccal segment
50
What are the consequences of the following bracket position errors:
Bracket is not seated correctly (wedge of material)
Bracket is too high or too low on the tooth
Bracket is tipped on the tooth
Bracket is placed too mesially or too distally
- Bracket will not deliver prescribed movement.
High - Intrusion . Low Extrusion
Tipped - wrong tip to tooth mesioangulate disto-angulate
Too mesially or distally - Rotate tooth
51
How would you monitor anchorage
- 3 dimensional assesment, note and photos and study model.
AP- loss of space with increased OJ
- Vertical- High buccal canine to come down.
- Lateral - canine palatal impacted with cross bite.
52
Wha things does etch do
- Expose enamel prism to increase surface area by increasing surface area
53
List 3 ways to create space
- distalising
- IPR
- Proclining lower incisors
- Expansion
- extractions
54
Who can consent to treatment for a pt who is handicapped and over the age of 16
Parent, legal guardian or carer
55
List three ways of increasing anchorage in a fixed appliance
- Vertical - IO elastics
- AP - bonding / banding 7s ,TPA ,
Heaadgear.
- Nance
- Moving anchor unit difficult.
- Making other teeth move easy
56
Briefly describe how a functional works
- They are constructed to posture the mandible forward and away from rest position. As a resultant soft tissue stretch generate forces that causes tooth movement.
57
What are the skeletal and dental effects
- Skeletal - Retrain maxilla growth by 1-2mm
Enhance mandibular growth by 2-3mm
- Procline lower incisors
Retroclined upper incisors
Medial movement of upper buccal segment
Distal movement of lower buccal segment
58
Define anchorage
- Source of resistance to forces generated in reaction to the active components of appliance. This is Newton third law for every action there is an equal and opposite reaction.
59
What is meant by the term ‘Duty of Care’
Being open and honest with patient Before tx
60
What is informed consent
Informed - signing consent form with all options risks, benefits, advantages disadvantages, given and letting them know or it's inform consent.
61
Name and define all ceph landmarks
-(A) Deepest concavity on anterior profile of
maxilla
(B) Deepest concavity on anterior surface of
mandibular symphysis
Anterior nasal spine (ANS)
Tip of anterior process of maxilla
Posterior nasal spine (PNS)
Tip of posterior nasal spine of maxilla
Pogonion (Pg)
Most anterior point on bony chin
Nasion (N)
Deepest point on frontonasal suture
Sella (S)
Midpoint of sella turcica
Orbitale (Or)
Most inferior point on orbital margin
Porion (Po) Upper and outermost point on bony external
auditory meatus
Condylion Most superior posterior point on the
condylar head
Gnathion (Gn) The most anterior inferior point on the
mandibular symphysis
Menton (Me)
Lowest point on mandibular symphysis
Gonion (Go) The most posterior inferior point on the
angle of the mandible
62
What are Andrews 6 Keys
- Correction of molar relationship
- Correctoon of crown inclination
- Correction of crown angulation
- Flat curve of spee
- No rotation
- No space
63
What is meant by 1st, 2nd, and 3rd order
1st order - in/out
2nd order- crown tip
3rd order- crown torque
64
What are intra and inter arch relationships and give examples of each
- Intra - Same arch - Crowding, spacing, rotation
- Inter- Opposite arch- Overjet, overbite, crossbite, scissor bite.
65
Name 3 standardised things on a ceph
- Assesment of skeletal, dental and soft tissue relationships in ap and vertical directions
66
What information is obtained from a ceph
- Assess skeletal , dental and soft tissue relationship in AP and vertical dimension.
67
Name the planes drawn on a ceph tracing
- SN line sella to Nasion stable landmark from approx 7 year old.
- Frankfort plane Po to Or
- Maxillary plane - ANS- PNS
-Mandibular plane - Gonion to Menton
68
Describe a Class I, II div I and II and Class III incisor class
Class I – the lower incisor tips occlude or lie below the cingulum plateau of the upper incisors; • Class II – the lower incisor tips occlude or lie posterior to the cingulum plateau of the upper incisors.Class III- lower incisor occlude before cingulum plateau off upper incisors.
69
Why is it necessary to use more than optimal force during space closure
Ideal forces in orthodontic tooth movement are those which over come capillary blood pressure which is 20-25gm/cm2 that's called optimal force. If we do not use more force tooth movement won't occur.
70
How many hours of force is needed to move teeth
- Light continuous force for 6 hours a day.
71
What are harnessed when using a functional appliance
- Growth?
72
Name 5 reasons for failure of space closure
- Too much force
- Less force
- too much friction
- Wire not seating properly Slop
- Calculus or plaque
- Ankylosed
73
What radiographs are taken to determine the position of unerupted canines
- USO and PA
- USO and DPT
74
What information can be obtained from an OPT
- Pathology , presence and position of teeth.
75
What does the term Gillick Competent mean
- child under age of 16 could now give consent in their own right if mental capacity to understand information and take decision.
76
How could you treat a patient who presented with a Class II division I malocclusion
-Upper removable appliance
- Functional appliance
- Fixed appliance
- Joint orthodontic / orthodonathic (surgical approach)
77
What is meant by the term ‘burning anchorage’
- Intentional wanted tooth movement of anchorage unit.
78
What are the special investigations carried out during an orthodontic assessment and list the reasons why
- MH - including previous tx , previous trauma
- Radiograph. To assess 3ps of teeth. If trauma teeth - investigate with GDP.
- Ceph- To assess severity of sk discrepancies.
- OH- To assess OH status if ready to start treatment . Or need any aid.
- Photos and Assesment .
79
Instructions to a pt with a functional appliance
- Bring lower jaw forward and then bite together. Inform Do not bite without posture.
- Duration of wear Fulltime/ part time./Hours
- How to look after it - Clean with soft brush and normal soapy water. Use of antibacterial tables to keep it clean and shiny.
- Any problem with brace book emergency appt.
- Encourage/ motivate pt to wear.the more you wear it less duration it takes in your mouth.
- If with expansion. Show them why and how to turn key with sheet to count.
80
What are the current ABC regs and where would you find them
81
What would you do if a patient had an anaphylactic shock
- Removed source of Allergen if possible
- Call 999
- Supine position
- To restore BP - Loose tight cloth
- ADM: Adrenaline 1:1000lm
- Oxygen : 15/L /min
- Repeat after 5 min if need
- Pt must admit in hospital given Steroid, antihistamines, monitor
82
What do you do to imps before sending them to the lab
- Check under light if any bubble or undercuts
- Sterlise and pack it with correct lab sheet.
83
What is a supernumerary tooth
- A tooth or like structure which develope in addition to normal series of 32 teeth.
84
What are the effects of having a supernumerary tooth
- midline diestema
- Delay eruption
- risk of cyst formation of adjustment tooth
- Crowding
85
Name the different morphological types
- Supplemental - Resemble a tooth - usually last series 2,5,8. Always check root on R/G.
- Conical - Peg shaped, often erupts between upper central incisors. May be inverted, risk of cyst formation / RR incisors.
- Tuberculate- barrel shaped, classically associated with failure of eruption- No root or less root.
- Odontome- Complex or compound
86
How would you clinically locate an unerupted canine tooth
- Look , Observe - bulge, inclination and colour of lateral incisors.
- Palpation of canine crown - Buccal and palatal
- Mobility of UC or U2s
87
If the canine appears higher on the OPT than the SMO what would this tell you about the position of the canine
- tooth is lying palatally, if it appear lower then buccally if same then line of arch.
88
What are the treatment options for an unerupted/impacted canine
- No TX
- Interceptive tx: Xtn C age 10-13. 62% crowded 78% uncrowded mouth possibility to normalised.
- Exposure and alignment
- Surgical removal.
89
List 2 methods of providing space to relieve maxillary crowding
- Distalisation
- Extraction
- IPR
- Expansion
90
If ANB is 0 what is the skeletal class
- Class III
91
What effect does trauma to a deciduous incisor have on the permanent successors
enamel discoloration,
enamel hypoplasia,
coronal dilaceration,
root dilaceration,
odontoma-like malformations,
alterations in eruption
92
What may cause retention of a primary molar 9 months after expected exfoliation
- Absence of permanent successor.
93
What are the inter and intra arch effects/features of a patient with a digit sucking habit
- Inter- Proclination of upper incisors and retroclination of lower incisors.
Intra- Open bite , cross bite
94
Name 4 ideal properties of alginate impression material
- fluid to record fine details
- Elasticity protect from undercuts
-Adhesion can be problem
- compatible with plaster and dental stone
- setting time affected by water temperate.
95
What is the role of a facebow record and when is it considered in orthodontics
- Facebows are calliper-like devices that record the relationship of the maxillary teeth to the position of the condyle when it is in the terminal hinge axis position and allows this information to be transferred to the articulator when mounting dental casts.
96
What is glass polyalkenoate
- GIC - Glass ionomer composer
97
What factors contribute to lower incisor crowding
- Inherent mesial migration
- Facial growth pattern and rotation
- Soft tissue pressure
- Jaw size decreasing with age
- Narrow contact points of lower incisors
98
Define the following:
Intercuspal position
Mandibular displacement
Mandibular deviation
- Intercuspal position : the complete intercuspation of the opposing teeth independent. of condylar position,
- Mandibular displacement- The difference between ICP- RCP
- Mandibular deviation - facial asymmetry and chin and dental midline deviations
99
What is the incidence of hypodontia
6.4% except 8s
- 25-35% of 8s
- 3% of 5s
- 2% of 2s
-<1% of 1s
100
What problems can result from the early loss of a deciduous tooth
- Crowded case - may result in neighbouring teeth drifting into space.This will depend on degree of crowding, patient age and location
- Less likely to occur in spaced arches
- Effect is greater in maxilla
101
If a lower deciduous first molar is lost unilaterally, what would you see clinically
- Centreline discrepancy .
102
1 What cells are responsible for the craniofacial skeleton
- Cranial neural crest cell
103
Define growth
- Growth refers to the increase in number and size.
104
3 What is the relevance of growth to orthodontics
- if growth present orthodontic tx is quicker.
- OB reduction
- distal movement of posterior teeth
- Space closure
- Occlusal setting
- Functional appliance treatment
- Use of RME
105
What is ossification
Process of bone formation
106
Ossification is formed in two ways, name them
- Intramembranouos - mesenchymal tissue
- Endochondral - cartilage
107
What phenomena is bone growth a function of
- support and regulation of calcium and phosphorus, as well as to repair any damage to the skeleton,
108
Which pharyngeal arch is the mandible derived from
First branchial arch:
Arch: mandible, incus, malleus, muscles of mastication, cranial nerves (CN) V2 and V3.
109
In what direction does the maxilla grow
- Forward and downward
110
Name two factors that influence growth
- Generics and environmental factors
111
Name the three stages of dental development
- Bud , cap and. Bell
112
Name three types of physiological tooth movement
Pre-eruptive tooth movement 2. Eruptive tooth movement 3. Posteruptive tooth movement.
113
Name four theories of tooth eruption
- Biomechanical / cellular theory
- Piezoelectric tension hypothesis
- The pressure tension hypothesis
- The hydrodynamic theory
114
What is a natal tooth
teeth that are already present at birth
115
When do deciduous teeth erupt
6-12 months
116
Name two general and local causes for delayed eruption
Local - a tooth in the path of eruption, insufficient space in the dental arch, or dental infection. Ectopic eruption,
General- genetics , endocrine disorders
117
What is ankyloglossa
Tongue-tie is where the skin joining a baby's tongue to the bottom of their mouth is shorter than usual. It sometimes makes it harder to breastfeed.
118
List two ways of classifying a malocclusion
- Angle's classification
-Andrews's classification
119
What is mesial drift
the tendency of teeth to move in a mesial direction within the arch with an aim to maintain interproximal contact between teeth.
120
What is the incidence of supernumeraries
1-2%
121
Where do they most commonly occur
- anterior segment upper central incisors
122
What is infraocclusion
-condition where teeth are found with their occlusal surface below the adjacent teeth, long after they should have reached occlusion. Many terms have been used to describe this con
123
What is dilaceration and how does it occur
-Dilaceration is a developmental disturbance in shape of teeth. It refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth.
- traumatic dental injury to the primary predecessor, idiopathic developmental disturbance, a retained or ankylosed primary tooth, and the presence of supernumerary tooth or teeth
124
List two causes of disrupted mineralisation
- Genetics
-Prolonged illness
125
What difference between impeded and impacted tooth?
- Impacted 5i: Space for unerupted tooth <\= 4mm
- Impeded- If tooth has erupted but is short of space so tips against neighbouring tooth scored as impeded. 4t
126
When planning anchorage what must you consider?
- All three dimensions.
- A/P dimension - extractions.
- Vertical - Use of removable appliance
- Transverse
- Number of teeth to be moved
-Distance they need to be moved
- Type of movement planned
- How anchorage demanding the case ( Class II mal with crowding and increased Overjet is far more than anchorage demanding.
- Soft tissue
- Type of appliance to be used.
127
3 ways of increasing anchorage in fixed appliances
- Add more teeth in the anchor unit - Binding second molars.
- Use of figure of eight when lighting.
- Use of HG, TPA, lingual arch or quad helix.
128
What happens if excessive force is applied.
- If excessive force is applied direct resorption of the bone doesn't occur due to compression of blood vessels
- Sterile necrosis ( Hyalinisation ) structure less microscopic appearance
- After few days indirect resorption occurs then tooth moves (undermining resorption)
- Pain for patient
- slow movement
- Root resorption
- Tooth may die
129
Name three types of anchorage in twin block appliance with midline screw?
- Reciprocal- Midline screw
- Intermaxillary unsung both arches
- vertical - Palatal vault
130
What Anchorage does TPA provide
- Compound
- Horizontal or AP
-vertical
131
What happens if excessive force is applied in lingual arch
- May Procline lower incisors
132
What Anchorage does quadhelix provide
- Reciprocal
133
What Anchorage does URA provide
- vertical
- If screw present - Reciprocal
134
What happens if you lose Anchorage
- Jeopardise successful treatment
- Loss of space
- unwanted tooth movement
- possible worsening malocclusion
- Increased Overjet and extraction space closed.
- Bilateral open bite when retracting high angle canine
- Nance wedged in palate.
135
What is burning Anchorage
- Intentional movement of anchor unit
- E.g. Intentional Mesial movement of molars as if too much space.
136
What are the use of high pull headgear
- Traction : Distal movement and intrusion of first molars 12-14 hours of 400-500g force per side.
- Extra oral Anchorage 250-300g force per side 10-12 hours.
137
Cervical headgear
- Backward and downward- Distalise and extrude
- Combi Headgear
- Distalise molars
138
How many hours force is needed to move teeth
- 6 hours
139
What happenes when optimal force applied and tooth movement
- The optimal force for tooth movement is below capillary pressure which is 20-25g/cm2.
- The pressure side- Periodontal ligament is compressed. With in seconds the alveolar bone bends and the blood supply is altered. When this pressure is continued over a period of hours there is chemical reaction within blood cells which release Cykotonis (Cytokines) and prostoglandis which in turn signals the need for osteoclasts to migrate to the area. Osteoclasts migrate to the area and begin direct bone resorption, which allow the teeth to move.
Tension side- PDL is stretched which again alter the capillary pressure and blood flow but this time in different way. This signals need for osteoblasts and fibroblasts to migrate to the area and lay down osteoids onto socket wall and new PDL fibre.
140
Osteoblast derived from
- Undifferentiated Mesenchymal cells considered stem cell from PDL.
141
What is RANK L
- Rank Ligand which is key regulator of bone remodelling-
- *RANKL is responsible for osteoclast recruitment and activation. *
- Act as Osteoclast receptors.
142
What determines the response from teeth?
- Pressure and tension with in PDL.
143
Name three cause of failure of eruption of upper central incisors
- Dilaceration
-Ankylosed
- Impaction due presence of supernumerary.
144
How would you determine if unerupted canine was lying buccally or palatal
- Vertical parallax - USO and DPT / PA and DPT
- Horizontal Parallax - USO and PA
If the canine appears higher on the OPT than the SMO canine is lying palatal
- If canine appear lower on DPT than SMO canine is lying buccally.
145
Four active component of URA
- Finger spring
- Canine retractor
- Z spring
- T spring
146
Name four type of functional appliance
- Twin block functional appliance - Bite blocks 70 degree to occlusal plane
- Frankel- Shields to hold check out of way- class I class II and (class III only Dentoalveolar change).
- Medium opening activator - allow nuvcal segments to erupt. Class II DIV 1 deep OB Overjet .
- Dynamax-
147
What are harnessed in use of functional appliance
- Masseter
- Temporalis
- Lateral Pterygoid
- Medial pterygoid
148
How does a twin block appliance work
- They are constructed to posture the mandible forward and away from rest position. As a resultant soft tissue ( muscle of mastication and orofacial) stretch generate forces that causes tooth movement.
SK effect - 1-2mm maxillary restrain.
- 1-2mm mandibular enhancements.
- Dentoalveolar effect - Procline lower incisor , Retroclined upper incisors, Mesial movement of upper buccal segment and distal movement of lower buccal segment.
149
What percentage is tooth movement and skeletal change
- Sk change 30%
- Dental alveolar change 70%
150
What are intra arch relationships and name for?
- Intra arch relationships are within an arch
- Crowding, rotations, spacing and supernumeraries.
151
What are intra arch relationships and name for?
- Intra arch relationships are within an arch
- Crowding, rotations, spacing and supernumeraries.
152
What are inter arch relationships
- Anterior/ posterior increased or reversed Overjet
- Vertical - Increased or reduced overbite
- Transverse - Crossbite or scissor bite.
153
Why do teeth move faster in children
- Greater physiological change still occurring
- PDL more cellular and wider
- More osteoblasts
154
What is used to prepare the tooth surface before bonding.
- Bristle brush / cups with slow handpiece to remove plaque
- Etchant 30-50% phosphoric acid for 15-20 seconds.
155
What happens during the setting process
- Polymerisation
156
What would you do differently in lower bond up for pt with Class III malocclusion
- If canine are distally angulated you might swap the left and right canine bracket over to reverse tip.
157
How would you treat candida infection
- Antifungal such as Nystatin
158
What tell tale sign of digit sucker
- Open bite either unilateral , bilateral or anterior.
- Proclined upper incisor
- Retroclined lower incisors
159
What treatment would you provide for digit sucker
- Interventions: sock, gloves or nasty nail varnish.
- Fit habit breaker
- No treatment until habit is broken
160
What is difference between displacement and deviation
- A displacement is premature contact and slide on closing and deviation is functional movement of mandible to avoid displacement
161
What is lateral excursion
- When mandible moves to the left or right
- Canine guided lateral excursion where canine guide movement
- Group function lateral guided excursion when more than canines are in contact.
162
6 reasons of failure to close space
- Occlussal interference
-Too much friction
- Binding
- too little force
- Presence of supernumerary
- Ideopathic
- Alveolar necking - Cause incomplete space closer
- Root angulation - Cause incomplete space closer
- Bend in wire stop space closer
- Retain deciduous teeth
163
What does DMUBS stands for?
Distal Movement Upper Buccal Segment
164
How could you measure degree of crowding
- Use an archwire from molar to molar and measure the length of wire then measure each tooth in the arch. Difference between two figures will give you degree of crowding
- Under 4mm of crowding can be treated by non Xtn.
- 4-8 mm may need Xtn of second premolars
- 8mm may need to extract first premolars
165
What are balancing extraction
- If tooth is lost one side then you match the other side
166
What are compensating extractions
- when you extract an upper tooth you extract the equivalent tooth in opposing arch.
