interceptive orthodontics

Question 1

what is interceptive orthodontics

Answer 1

any procedure aimed at reducing or eliminating the severity of a developing malocclusion

Question 2

what might need interceptive ortho (14)

Answer 2

x bite
digit sucking habit
supernumerary teeth
midline diastema
increased OJ
reverse OJ
increased OB
early loss of primary teeth
developing crowding
poor prognosis of FPM
impacted FPM
infra occluded teeth
hypodontia
delayed eruption i.e. u/e canines or max incisors

Question 3

what is anterior x bite & possible issues

Answer 3

abnormal relationship between opposing teeth in a buccopalatal or labiopalatal direction
issues - toothwear, gingival recession, displacement on closure

Question 4

what features of anterior x bite will make it amenable to correction via URA (3)

Answer 4

1. tooth in x bite palatally tipped
2. good OB indicated end of tx stability
3. adequate space to move forwards
   manage via URA (2x4 appliance i.e. brackets on incisors & 6s)

Question 5

issues with posterior x bite (5)

Answer 5

• displacement on closure
• tooth wear
• facial asymmetry
• teeth may erupt in displaced ICP position
• potential TMJ problems

Question 6

mx of posterior x bite

Answer 6

1. URA (mid palatal screw)
2. quad helix
3. RME i.e. rapid maxillary expansion

Question 7

why tx increased OJ in mixed dentition

Answer 7

1. increased risk of trauma
2. poor aesthetics (teasing / psychosocial problems)

Question 8

aetiology of increased OJ

Answer 8

1. skeletal - usually class II, mandibular deficiency most common
2. soft tissue - lower lip trap, hyperactive lower lip
3. dental - upper incisor proclination, lingual displacement of lower incisors, potentially digit habit

Question 9

mx of increased OJ in growing pt

Answer 9

1. URA for simple retraction of upper incisors
2. attempt growth modification by either
   - tooth borne appliances i.e. twin block or activator (andreason)
   - soft tissue borne appliances i.e. myofunctional regulator (Frankel)

Question 10

patient selection for tx of increased OJ (7)

Answer 10

1. growing pt
2. pt concerns
3. dental health risk
4. pt motivation
5. large dentoalveolar contribution to aetiology
6. absence of significant crowding
7. increased OB

Question 11

therapeutic effects of growth mod in increased OJ

Answer 11

postures mandible down and forwards to encourage mandibular growth
restrains maxillary growth
remodels glenoid fossa
retroclines maxillary incisors & distalises molars
proclines mandibular incisors & mesialises molars

Question 12

problems with reverse OJ (4)

Answer 12

• displacement on closure
• incisal edge wear
• difficulty eating
• speech problems

Question 13

aetiology of reverse OJ

Answer 13

skeletal - class III skeletal base, hypoplastic maxilla, prognathic mandible
dental - mandibular displacement, retained upper primary incisors

Question 14

mx of reverse OJ in growing pt

Answer 14

1. simple proclination of upper incisors via URA
2. attempt growth modification
   - chin strap / cup
   - functional appliances i.e. reverse twin block
   - protraction headgear

Question 15

mode of action of functional appliances for reverse OJ

Answer 15

alter force exerted by lips & cheeks
disengages occlusion

Question 16

if see anterior x bite must check for

Answer 16

mandibular displacement
as this will determine whether we intercept or not i.e. if displacing need to intercept but if not then can leave until age for rest of ortho tx
basically early intervention

Question 17

issues with mandibular displacement in anterior x bite

Answer 17

1. TMJ problems
2. occluding then displacing can cause:
   - excess force on lower incisors so they become more mobile & proclines them leading to gingival recession ( can see root shine through)
   - attrition on lingual of lower and labial of upper

Question 18

to correct anterior x bite in practice

Answer 18

URA with z spring & posterior bite plane
make sure no lateral incisor in way of moving central forwards & don’t have clasping arrangement that will get in way of moving teeth
no ABP as will cause over eruption of molars then causing reduced OB but we want significant OB for end of tx stability

Question 19

issues & tx of deep OB

Answer 19

issues - palatal ulceration & gingival stripping
tx -
- URA with FABP; will allow lower molars to erupt. pt must be growing to accommodate the increase in vertical dimension
- potentially convert to class II div 1 with twin block

Question 20

issues with digit sucking habit

Answer 20

AOB / reduced OB
proclined upper incisors & retroclined lower incisors
increased OJ
posterior x bite

Question 21

aetiology of digit sucking habit

Answer 21

> 6hr duration
prevention of eruption of incisors
labio lingual pressure on incisors
lowering of tongue position
unopposed buccinator pressure against D and E
creates negative IO pressure not a lot but enough to cause unilateral posterior x bite
if no displacement - arch width discrepancy between upper and lower i.e. wide mandible and narrow upper arch; pt will usually have asymmetry

Question 22

key to tx of digit sucking habit

Answer 22

habit must be stopped prior to active tx
try BMT / nail polish / removeable habit breaker
want thumb out as early as possible as greater chance of spontaneous closure as 8-9 as opposed to 11-12

Question 23

components for URA habit breaker

Answer 23

1-2 palatal goal posts
why 2? - expand upper arch & correct x bite at same time. 2 goal posts so they don’t cross the midline

Question 24

problems with supernumerary teeth

Answer 24

1. impeded eruption
2. delayed eruption
3. aesthetics
4. damage to adjacent teeth
5. 10% diastemas due to supernumerary
6. maxilla > mandible
7. M > F

Question 25

types of supernumerary

Answer 25

1. conical - close to midline, 1-2 in no, tend not to prevent eruption but may displace centrals, xla only if erupt / impede tooth movement 2. tuberculate - main cause of failure of eruption of centrals, usually palatal, remove +/- surgical exposure of centrals 3. supplemental - normal morphology, tend to XLA, decision based on tooth form & position 4. odontome - less common, compound & complex forms

Question 26

aetiology of median diastema

Answer 26

developmental generalised spacing hypodontia (absent 2s) midline supernumerary (mesiodens) proclination of upper incisors low fraenal attachment pathology

Question 27

FPM poor prognosis

Answer 27

wouldn't routinely balance as too far posterior to cause centre line shift rule of thumb - consider compensation in U if L needs to go (7 will get caught behind if 6 over erupts) don't have to take L if taking U as L doesn't tend to over erupt and space closure is more rapid in the maxilla (roots more distal & crown more mesially angulated so quickly moves forwards)

Question 28

guidance on FPM

Answer 28

- don't routinely take FPM in upper unless specific occlusal reasons for doing so or else significant risk for over eruption - angulation lower 2nd molar makes with occlusion i.e. if mesial & 8s forming this is favourable; 8 is appropriate age to be looking at this gold standard = refer to centre with combined paediatric & orthodontic services for opinion

Question 29

impact of early loss of Es

Answer 29

major cause of impacted 5s

Question 30

compensating & balancing of FPM

Answer 30

upper 6 xla - do not compensate lower 6 xla - consider compensating balance - only in lower & if crowded guideline = RCS clinical effectiveness committee 2009

Question 31

loss of mandibular FPM summary

Answer 31

ideal timing for xla = bifurcation of 7s forming / age 8-9yrs / good spontaneous closure between 7 & 5 early loss = distal migration of 2nd premolar late loss = poor spontaneous space closure & mesial tipping & lingual rolling of 7s

Question 32

loss of maxillary FPM summary

Answer 32

timing less critical than in mandible as better space closure if space required consider delaying until eruption of 7 & place space maintainer is possible

Question 33

early loss of primary teeth

Answer 33

early loss of a and b - minimal effect on centre line - don't balance or compensate early loss of c - consider balance to maintain centreline in crowded dentition - do not compensate early loss of d and e - space loss especially in upper - consider space maintenance - little effect on centre line no need to balance

Question 34

impact of early loss of primary teeth

Answer 34

1. loss of Es = major cause of impacted 5s will often erupt inside of the arch if given time 2. effect in upper arch more severe than lower 3. the further back in the arch the more marked the effect on crowding

Question 35

when to use space maintenance

Answer 35

1. early loss of primary teeth 2. early loss FPM 3. traumatic loss / delayed eruption of maxillary incisor 4. preserve Leeway space note - good OH crucial & best space maintainer is primary tooth itself

Question 36

factors influencing rate of space closure following xla

Answer 36

- age at loss; too early slows eruption of permanent teeth & too late speeds up eruption - degree of crowding - which arch i.e. upper shows quicker space closure

Question 37

development of FPM

Answer 37

derived from primary dental lamina coronal development complete by 3yrs erupts at 6-7yrs root formation complete at 9-10

Question 38

predictors of successful SPM eruption following interceptive FPM removal

Answer 38

1. SPM within alveolar bone 2. early mineralisation of bifurcation 3. mesio-distal angulation 4. presence of TPM

Question 39

when to xla FPM

Answer 39

when SPM is developing i.e. between 8-10yrs as this will cause the least disruption to the occlusion if <8yrs or >8yrs SPM & 2nd premolar can drift into xla space, tip, rotate & produce spacing within dental arch with poor occlusal contacts

Question 40

types of space maintainer available

Answer 40

1. tooth (even badly decayed primary molars can be restored for a few years) 2. band & loop - design of choice for a single tooth space 3. lingual / palatal arch - best for bilateral spaces 4. URA - avoid unless appliance can be used for active orthodontic tx

Question 41

3 features of primary dentition than indicate good development

Answer 41

1. incisor spacing 2. anthropoid spacing - mesial to max primary canine and distal to mandibular primary canine 3. straight or mesial step primary 2nd molar occlusion

Question 42

impacted FPM aetiology & effect

Answer 42

aetiology - eruption angle, ectopic cyst, morphology of 2nd primary molar crown, small maxilla effect - pulpitis of E / premature exfoliation of E

Question 43

tx options for impacted FPM (3)

Answer 43

1. observe for ~6mths as 66% disimpact by age 7 2. XLA E - regain space for premolar or tx crowding at later stage 3. dis impact - separators / band E and bracket 6 with open coil / distal discing of E / URA with finger spring attachment on 6

Question 44

primary molar infra occlusion key factors

Answer 44

temporary ankylosis 8-14% lower D most common mandible > maxilla M : F = percussion sound blurring or absence of pdl on radiograph usually shed normally if perm successor present

Question 45

mx of infra occluded primary molars

Answer 45

premolars come down between roots of primary so won't be able to palpate if developing normally MX DEPENDS ON PRESENCE / ABSENCE OF 5S 5s present & in good position = xla & space maintenance (if no xla, adjacent teeth tip, e becomes submerged & gets much worse) 5s absent = must consider prognosis of E & how it will fit with rest of dentition i.e. other features of malocclusion that need addressed so can xla & close space via ortho or retain for as long as possible & place onlay if infra occluded primary molar below contact point mark as urgent