Test 2 ortho final notes

Question 1

What are the common variations in eruption that lead to clinical problems in space for permanent teeth?

Answer 1

Eruption of mandibular 7s before loss of Es or eruption of 5s

Eruption of canines before or at the same time as first premolars in the upper arch

Asymmetry of the position of teeth in opposite sides of the same arch

Question 2

What causes eruption of mandibular 7s before loss of Es or eruption of 5s? What does it lead to?

Answer 2

Can be a part of normal variation/sequence of eruption. It leads to a reduction of space available for 5s to erupt which leads to impaction. Can eventually lead to 8s impaction.

Question 3

What is the treatment for misalignment caused by eruption of mandibular 7s before the loss of Es or eruption of 5s?

Answer 3

Mandibular orthodontic appliance on the lower lingual arch to hold molars back and open up space for 5s to erupt.

Question 4

Why is eruption of canines before or at the same time as the first premolars of the upper arch a problem?

Answer 4

This eruption is out of sequence in the upper arch (normally 4s at 10/11, upper 3s at 12) This leads to the maxillary canine being forced to move labially and to become prominent creating the fang appearance.

Question 5

How is the misalignment caused by eruption of canines before or at the same time as the first premolars treated?

Answer 5

Space is created fro maxillary canine to erupt by using orthodontic treatment to widen the dental arch.

Distalisation

Extraction

Question 6

When should asymmetry in position of teeth in opposite sides of the same arch be investigated?

Answer 6

If there is more than 6 months difference in eruption time.

Question 7

What are the reasons for asymmetry of position of teeth in opposite sides of the same arch?

Answer 7

Retained primary teeth due to failure of root resorption resulting in impaction of permanent successor.

Retained primary tooth due to crown of permanent tooth missing the root of primary tooth during development leading to altered eruption pathway and impaction.

Ankylosis of primary teeth can prevent further eruption of the successor.

Question 8

How are the reasons for asymmetry of position of the teeth in opposite sides of the same arch treated?

Answer 8

Extraction of tooth blocking the eruption to give pathway for successor to erupt.

In the case of failed root resorption it is important to use a bonded attachment to drag the tooth occlusally.

With ankylosis, use an ortho band to resolve tilting of adjacent teeth and use bonded attachment to bring tooth to correct position if necessary.

Question 9

Discuss the variations in eruption that are most likely to be associated with clinical problems in space for permanent teeth. 4/3/5

EXAM question

Answer 9

Eruption of Mandibular 7s Before Loss of Es or eruption of 5s:

• Can be part of normal variation/sequence (both in the 12 year old group)
• Leads to reduction of space available for 5s to erupt -> impaction
• Implications for 8s eruption (mesial impaction????)
• Tx: Mandibular orthodontic appliance (lower lingual arch) to hold molars back and open up space for 5s to erupt

Eruption of Canines before or at the same time as first premolars in upper arch:
• Out of sequence (normally 4s at 10/11, upper 3s at 12), normal for lower
• Not enough room to accommodate 4s -> Leads to maxillary canine being forced labially and become prominent (fang appearance)
• Tx: To create space for maxillary canine
o Ortho tx to widen dental arch
o Distalisation
o Extraction

Asymmetry of Position of Teeth in Opposites sides of the same arch:
• Normal variation of few months for asymmetry in eruption between two sides
• > 6 months difference in eruption= need investigation

Reasons for asymmetry of position of teeth in opposite sides of the same arch could include:
• Retained primary teeth due to failure of root resorption resulting in impaction of permanent successor -> extract retained primary teeth to give pathway for successor to erupt + bonded attachment to drag it occlusally
• Retained primary tooth due to crown of permanent missing the root of primary tooth during development -> altered eruption pathways and impaction -> extract primary tooth to allow successor the correct pathway to erupt
• Ankylosis of primary teeth preventing further eruption of successor -> Extract ankylosed teeth (to create space for eruption) -> ortho band to resolve tilting of adjacent teeth + bonded attachment to bring tooth to correct position if necessary
o Typical omen: If nearby teeth have been erupting past it and bringing bone up + this one starts being relative submerged because bone level still same and the adjacent teeth start tilting over it- diagram

Question 10

Where does incisor liability come from? Why is it a problem?

Answer 10

The width of upper incisors is more than the primary incisors and the jaw does not get bigger.

Leads to incisal crowding during mixed dentition phase. Space is needed to accomodate larger incisors

Question 11

How much incisor liability is there?

Answer 11

Maxilla: 7.6mm

Mandible: 6mm

Question 12

What are the sources of space needed to overcome incisor liability?

Answer 12

Source 1: inter-canine width

Source 2: Labial eruption of incisors

Source 3: Distal drift into spaces

Question 13

How does inter-canine width help overcome incisor liabiltiy?

Answer 13

Canines erupt laterally which increases inter-canine width which widens the arch.

Widening of the arch provides 2mm extra space in the lower.

Question 14

Who gets more intercanine width increase males or females? Implications?

Answer 14

Males, thus girls are more prone than boys to incisal crowding.

Question 15

How does labial eruption of incisors help with overcoming incisor liability?

Answer 15

Incisor tooth buds of U/L are located lingually but they erupt labially (forward leaning relative to position of the primary which are quite upright) -> Increased arch length

Increase in arch length provides 1 - 2mm of space.

Question 16

Which arch has more labial eruption of incisors?

Answer 16

More maxillary than mandibular (thus maxilla deals with crowding better)

Question 17

How much space is offered by distal drift into spaces?

Answer 17

Approximately 1mm worth of room.

Question 18

What spaces does distal drift occur into?

Answer 18

Developmental spaces: 
Generalized/interdental space (Space between incisors in primary dentition (eg maxillary diastema during ugly duckling period))
Primate spaces (Maxillary between lateral incisor and canine and mandibular between canine and first primary molar)

Leeway space:
Generated by the 3/4/5s being narrower mesial-distally than C/D/Es.

Question 19

Indicate the sources of space to overcome incisor liability:

EXAM question

Answer 19

Incisor liability: Caused by the width differential caused by permanent incisors being wider than primary incisors + but jaw doesn’t get wider so space deficit
• In Mx: 7.6mm
• In Mn: 6mm
• Leads to incisal crowding during mixed dentition phase.
• Thus space needed to accommodate larger incisors.

Source 1: Inter-canine Width
• Canines erupt laterally  increases inter-canine width  widens the arch
• The widening of the arch provides 2mm of space in the lower
• More in boys than girls, thus girls more prone to Incisal crowding. More in max?
Source 2: Labial Eruption of Incisors
• Incisor tooth buds of U/L are located lingually, but they erupt labially (forward leaning relative to position of the primary, which are quite upright)  increase arch length
• Increase in arch length) provides 1-2mm of space
• More max than man (thus max deals with crowding better)
Source 3: Distal drift into spaces
This offers about 1mm worth of room for relief of Incisal liability

Developmental Spaces
• Generalised/interdental spaces:
o The ‘slack’ offered by spaces between incisors in primary dentition is utilised by the larger permanent incisors.
o E.g. maxillary diastema (up to 2mm) disappears as permanent canines erupt and push lateral incisors (and thus central incisor) mesially
• Primate Spaces:
o The ‘slack’ offered by the Mx primate space between B and Cs (1.7mm) is utilised when the permanent lateral incisors drift distally, partly accommodating the larger size of incisors
o The ‘slack’ offered by the Mn primate space between C and Ds (1.5mm) is partially utilised when the permanent canines drift/tilt distally, providing extra space for the larger incisors (slight increase in inter-canine width)
Leeway Space
• Generated by the 3/4/5s being narrower mesial-distally than C/D/Es
o Mx: 1.5mm per side
o Mn: 2.5mm per side
• Provides space for larger permanent incisors to drift a bit distally = alleviate crowding

• Graph shows an increase in antimere distance= inter-canine distance (and arch width) upon the eruption of 3s and also eruption of incisors

Question 20

How many stages of sexual maturation are there for girls?

Answer 20

3

Question 21

What are the features of stage 1 sexual maturation in girls?

Answer 21

Coincides with beginning of the pubertal growth spurt.

Breast formation is seen with appearance of bud breast shape and increase in areola diameter

Early pubic hair which is slightly pigmented and sparsely distributed along the labia

Question 22

What are the features of stage 2 sexual maturation in girls?

Answer 22

Peak of pubertal growth spurt occurs at this stage.

Noticeable breast development is seen with growth + elevation of breast + areola with smooth contour.

Pubic hair is darker, coarser, curlier, and more widespread

Axillary hair is seen in armpits

Question 23

When is stage 2 of sexual maturation in females seen?

Answer 23

12 months after stage 1

Question 24

When is stage 3 of sexual maturation in females seen?

Answer 24

12 - 18 months after stage 2

Question 25

What happens during stage 3 of sexual maturation?

Answer 25

Growth spurt is complete

Broadening of hips and accumulation of adult fatty tissue

More adult distribution of pubic hair (medial of inner thighs)

Completed breast development (More adult contours, areola and papilla forming a secondary mound)

Onset of menstruation/menarche

Question 26

How does sexual maturation influence treatment?

Answer 26

The effectiveness of orthodontic treatment is enhanced if it is done during a period of high jaw growth or change in dentition to fix alignment.

An adolescent growth spurt in length of the mandible occurs concurrently with the general adolescent growth spurt (More growth of mandible relative to the maxilla due to cephalocaudal gradient)

Girls have a “juvenile acceleration” in jaw growth 1 - 2 years before the adolescent growth spurt

Thus by assessing general growth, we can make an inference on the stage of jaw growth and this influences timing of treatment.

These adolescent ‘spurts’ occur during the mixed dentition stage before 12 (as physical growth all but completes when the 5s and 7s erupt to complete the transition into permanent dentition)

Question 27

When should orthodontic treatment occur in girls?

Answer 27

It should commence while the patient is still in the mixed dentition stage (before eruption of all succedaneous teeth)

Question 28

Describe the stages of sexual maturation in girls:

EXAM question

Answer 28

Stage 1: (11 years old)
• Coincides with the beginning of the pubertal growth spurt – benign growth spurt
Initial signs of sexual maturation:
• Breast formation- appearance of bud breast shape, areola diameter increases
• Early pubic hair- slightly pigmented – sparsely distributed along labia
Stage 2: (12 years old)
• 12 months after stage 1
• Peak of pubertal growth spurt
• Noticeable breast development- growth + elevation of breast + areola w/ smooth contour
• Pubic Hair- darker, coarser, curlier, more widespread
• Axillary hair in armpits
Stage 3: (13 ish years old)
• 12-18 months after stage 2
• Growth spurt complete
• Broadening of hips- accumulation of adult fatty tissue
• More adult distribution of pubic hair: Medial of inner thighs
• Completed breast development: More adult contours, areola and papilla forming a secondary mound
• Onset of Menstruation/menarche
Treatment Implications
• The effectiveness of orthodontic treatment is enhanced if it is done during period of high jaw growth or change in dentition to fix alignment etc.
o E.g. Able to correct Class II jaw relationships via headgears (holding maxilla while mandible grows forward to alleviate mandible deficiency) or intra-oral devices (Bionator- hold mandible forward and guide posterior eruption) etc.
• An adolescent growth spurt in the length of the mandible (and maxilla to a lesser extent) occurs concurrently with the general adolescent growth spurt (more growth relative to maxilla due to cephalocaudal gradient- leads to differential jaw growth)
• Girls also have a “Juvenile acceleration” in jaw growth 1-2 years before adolescent growth spurt (of at least equal magnitude)
• Thus by assessing general growth (including secondary characteristics)-> allows an inference of stage of jaw growth -> influences timing of treatment
• These adolescent ‘spurts’ occur during the mixed dentition stage before 12 (as physical growth all but completes when 5s and 7s erupt to complete the transition into permanent dentition)

Thus Orthodontic treatment for girls should commence while the patient is still in the mixed dentition stage (i.e. before eruption of all succedaneous teeth)

Question 29

What are the 3 theories of lower incisor crowding seen in individuals in their early 20s who previously had good alignment?

Answer 29

3rd molar theory

Begg’s interproximal wear theory

Late mandibular growth

Question 30

What is third molar theory?

Answer 30

Third molars cause incisor crowding by pushing dentition mesially.

Question 31

Why was third molar theory thought to describe the cause of incisor crowding?

Answer 31

3rd molar eruption occurs at the same time as onset of crowding and 8s are often impacted as there is often insufficient growth in the length of the mandible to accomodate for it.

For this reason it was thought the impacted 3rd molars pushed everything mesially forcing the incisors together.

Question 32

What evidence goes against third molar theory?

Answer 32

Lower incisor crowding occurs just as often in people missing 8s congenitally.

Studies show link between 8s and incisor crowding is clinically insignificant.

Question 33

What is Begg’s interproximal wear theory?

Answer 33

Interproximal wear seen in primitive societies with coarser diets yields the necessary interdental space that can be used by the mesially drifting permanent molars to avoid late incisor crowding.

Lack of interproximal wear in societies with refined diets means no extra space which leads to crowding.

Question 34

What evidence goes against Begg’s interproximal wear theory?

Answer 34

Indigenous Australians now have refined diets and still don’t develop incisal crowding.

Extraction of 4s did not avert incisal crowding

More likely due to higher resting tongue position (position of teeth is mainly caused by soft tissue pressure)

Question 35

What is the currently accepted theory for late incisal crowding?

Answer 35

Small amount of mandibular growth occurs in early 20s causing a relative forward translation of the mandible (as growth of other facial structures is minimal due to cephalocaudal gradient)

This forward growth/rotation of the mandible carries dentition forward and incisors encounter resistance from the lips causing lower incisors to move more lingally to an upright position and this decreases arch length and causes incisor crowding.

Question 36

What evidence is there of late mandible growth which leads to incisal crowding?

Answer 36

More late mandibular growth = higher risk of incisal crowding

Incisal crowding will occur regardless of occlusal contact of incisors. Occurs even in those with anterior open bites from previous backward rotations of the mandible.

Lingual displacement and crowding upon late mandible growth was shown in Bjork’s implant studies.

Question 37

What is classical conditioning?

Answer 37

Learning by association. When a neutral stimulus becomes associated with an unconditioned stimulus (that leads to an unconditioned response), the neutral stimulus eventually becomes conditioned and can directly induce the said response regardless of presence of stimulus (pavlov’s dog).

An association between conditioned stimuli and unconditioned stimuli can be reinforced or weakened through multiple occurences increasing or decreasing the chance of a conditioned response

Question 38

How does classic conditioning apply to a dental setting?

Answer 38

Can occur in a child’s first visit to the dentist if the child previously attended a hospital/paediatrician and was exposed to an unpleasant stimulus that led to a negative response.

o They might have had a painful injection (unconditioned stimulus) that elicited a negative response (e.g. fear and crying).
o A neutral stimulus among that particular setting, such as white coats can then become associated with the painful injection (and subsequent fear/crying).
o When the child visits the dentist and sees the white coat, the conditioned stimulus of the white coat may directly elicit the fear and crying that was normally in response to pain.

For this reason it is important to make the dental clinic look and feel different to a hospital or doctors office by using colourful surroundings and clothing and fun waiting room activities to avoid exposure to a conditioned stimulus and eliciting a conditioned response.

Question 39

What is generalisation and how does it occur?

Answer 39

Generalisation can occur when association with the unpleasant stimulus becomes generalized to a wider range of neutral stimuli leading toa wider range of things that can elicit a conditioned response.

Question 40

What is discrimination?

Answer 40

Discrimination occurs when the child differentiates between harmless neutral stimuli and unpleasant stimuli.

Question 41

How can discrimination be achieved in a dental clinical setting?

Answer 41

By inviting them to observe other harmless exams being performed or avoiding unpleasant treatment in their first visit, the child learns to discriminate and disassociate the dental office (where no painful stimulus occurs) with the previous medical office (where painful stimulus and response occured)

Thus the generalized conditioned response of crying when they see any clinic will cease.

Question 42

What is the period of formal operations?

Answer 42

Seen after the age of 11 in adolescence through to adulthood throughout highschool.

It is the final stage of piaget’s 4 stage cognitive development theory. (sensorimotor, pre-op, and concrete)

Child’s cognitive development has reached levels similar to adults.

Question 43

What are the features of the period of formal operations?

Answer 43

Child is now able to think in abstract terms.

Renewed egocentrism: Imaginary audience

Increased risk taking: Personal fable

Question 44

How is a child able to think in abstract terms in the period of formal operations? What does this mean?

Answer 44

o Able to comprehend abstract concepts such as ‘health’, ‘disease’, ‘aesthetics’ and ‘prevention’

o Should link advice to abstract concepts of why it’s necessary (E.g. brush your teeth is important so you won’t develop decay and dental disease)

o Don’t talk in condescending simplified concrete terms

Question 45

What happens during period of renewed egocentrism?

Answer 45

Time of great physical and emotional change leading to cognitive fixation on oneself.

Belief that everyone is watching/judging their actions/appearance as if there is an imaginary audience watching them all the time.

Question 46

How does the period of renewed egocentrism apply to dental treatment?

Answer 46

Their attitude towards dental treatment becomes closely influenced by what they perceive as the reaction of their peers. (the audience). This makes them unlikely to proceed with treatment they think will get ridiculed (braces) and are likely to proceed with treatment they think will improve their standing among their peers.

OHI will be better received if framed around how it will improve their standing with their audience (teeth look nicer with no holes and rots)

Potential concerns about treatment application to peer group needs to be explored -> Treatment should be patient guided to re-evaluate the actual reception of their audience, rather than being flat out dismissed. (eg guide them into realising the reaction of their friends to wearing interarch elastics isn’t as negative as they think, or getting them to at least trial the braces to gauge the reaction of their peers)

Question 47

What are the implications of the increased risk taking (personal fable) stage of development?

Answer 47

Self-fixation also manifests in the idea that they are unique, and as such the consequences of actions might occur in others but not in them. (eg others will be fined for speeding but they won’t)

Question 48

How does the increased risk taking (personal fable) stage of development affect dentists?

Answer 48

OHI and other advice that warns of consequences won’t be effective as patient will dismiss it as something that won’t happen to them.

Show them it’s already starting to happen on them.

Question 49

What is classical conditioning and how does it apply to dentistry?

Exam question

Answer 49

• When a neutral stimulus becomes associated with an unconditioned stimulus (that leads to a unconditioned response), the neutral stimulus eventually becomes a conditioned stimulus and can directly induce the said response with/without the unconditioned stimulus.
• Can occur in child’s first visit to the dentist if the child previously attended a hospital/paediatrician and was exposed to a unpleasant stimulus that led to a negative response
o They might have had a painful injection (unconditioned stimulus) that elicited a negative response (e.g. fear and crying).
o A neutral stimulus among that particular setting, such as white coats can then become associated with the painful injection (and subsequent fear/crying).
o When the child visits the dentist and sees the white coat, the conditioned stimulus of the white coat may directly elicit the fear and crying that was normally in response to pain.
• Thus important to make dental clinic look/feel different from hospital- e.g. colourful décor, colourful clothing, fun waiting room activities to avoid exposure to a conditioned stimulus and eliciting the conditioned response.

• The association between a conditioned stimuli and unconditioned stimuli can be reinforced through multiple concurrences, increasing the chance of a conditioned response.
• OR weakened if not reinforced (e.g. if second visit isn’t also unpleasant), eventually extinguishing the conditioned response.

• Generalisation can occur when association with the unpleasant stimulus becomes generalised to a wider range of neutral stimuli (e.g. the reception area), leading to a wider range of things that can elicit the conditioned response.

Discrimination occurs when the child differentiates between a harmless neutral stimuli and unpleasant stimuli.
• By inviting them to observe other harmless exams being performed or avoiding unpleasant treatment in their first visit, the child learns to discriminate and disassociate the dental office (where no painful stimulus occurs) with the previous medical office (where painful stimulus and response occurred).
• Thus the generalised conditioned response of crying when they see any clinic will cease.

Question 50

What happens during the formal operations stage and how does this apply to dentistry?

Answer 50

Period of Formal Operations: 11+, adolescence through to adulthood, high school
• Final stage of Piaget’s 4 stage cognitive development theory (Sensorimotor, pre-op, concrete)
• Child’s cognitive development has reached levels similar to adults
• Child able to think in abstract terms:
o Able to comprehend abstract concepts such as ‘health’, ‘disease’, ‘aesthetics’ and ‘prevention’
o Should link advice to abstract concepts of why it’s necessary (E.g. brush your teeth is important so you won’t develop decay and dental disease)

o Don’t talk in condescending simplified concrete terms
• Renewed egocentrism: Imaginary Audience [Elkind]
o Time of great physical and emotional change lead to cognitive fixation on oneself
o Belief that everyone is observing/judging their actions/appearance- as if there is an imaginary audience watching them all the time
o Their attitude towards dental treatment (e.g. braces) becomes closely influenced by what they perceive as the reaction of their peers (the audience)

• Unlikely to proceed with a treatment they think will generate negative judgement from their peers- e.g. if they think they will get ridiculed for wearing braces
• Likely to proceed with a treatment they think will be received positively by their ‘audience’ – e.g. aesthetic improvement

o OHI will be better received if framed around how it will improve their standing with their audience- e.g. teeth look nicer when seen by their peers and no rots and holes
o Potential concerns about treatment (e.g. if worried they will be judged or singled out) need to be explored -> pt guided to re-evaluate the actual reception of their audience, rather than being flat out dismissed (E.g. guide them into realising the reaction of their friends to wearing interarch elastics isn’t as negative as they think, or getting them to at least trial the braces to gauge the reaction of their peers)

• Increased risk taking: Personal Fable [Elkind]
o Self-fixation also manifests in the idea that they are unique, and as such the consequences of actions might occur in others but won’t happen with them
o E.g. they think that others will get fined for speeding, but they won’t
o OHI and other advice that warns of consequences (e.g. caries if no brushing) won’t be effective as patient will dismiss it as something that won’t happen to them
o Show them it’s already starting to happen on them (decalcification)