Ortho Level 4 unit C

Question 1

Why was orthognathic surgery developed?

Answer 1

Allowed the mandible to be moved forward or back,

Made it possible to reposition the maxilla in all three planes of space and in multiple segments if necessary

Were developed for surgical repositioning of the chin and dentoalveolar segments.

Question 2

What was the key development for modern orthognathc surgery of the mandible?

Answer 2

The saggital split osteotomy of the ramus giving good bone to bone contactfor mandibular advancement.

Question 3

What was the key development for modern orthognathc surgery of the maxilla?

Answer 3

The development of the LeFort I osteotomy technique, which allows movement of the maxilla in all three planes of space.

Question 4

Why is repositioning of the maxilla done so often now?

Answer 4

The maxilla can be repositioned without concern about maintaining joint function

Question 5

What is the most frequently used orthognathic procedure?

Answer 5

The saggital split osteotomy which can be used for mandibular advancement.

Question 6

How is a saggital split osteotomy done?

Answer 6

Completely intraorally, an incision is made in the mandibular vestibule. A cut is made through the medial cortical bone of the ramus above the lingula and extended diagonally across the front of the ramus to the second molar area then down to the lower border.

Osteotome is then used to split the ramus through medullary bone so that the inferior alveolar neurovascular bundle is with the tooth-bearing segment allowing it to be moved forward and rotated as desired.

Teeth are then brought back to desired occlusion.

Question 7

How does backward movement of the mandible differ from forward movement?

Answer 7

Backward movement requires removal of a segment of bone on the facial side of the split but everything else is similar whether the mandible is advanced or retracted.

Question 8

What are the steps to a LeFort osteotomy?

Answer 8

LeFort 1 incision: The sinus walls are sectioned above the roots of the teeth and the roof of the mouth.

Maxilla is separated from the pterygoid plates so that it can be rotated down anteriorly.

Maxilla is then moved in the down-fractured position so that it can be approached from above

The maxilla is then repositioned vertically and moved forward or back as planned

Question 9

Who needs orthognathic surgery?

Answer 9

Patients with a severe skeletal problem or a very severe dentoalveolar problem, too severe for correction with orthodontics alone

Question 10

How severe does a malocclusion have to be before it is too severe to be corrected by orthodontics alone?

Answer 10

Guidelines for this are provided by the “envelope of discrepancy” which is the maximum viable distance a tooth can be moved orthodontically.

Question 11

What are the key points to consider about tooth movement regarding the envelope of discrepancy?

Answer 11

the envelope reflects bodily movement and also takes long-term stability into account

If teeth are severely tipped, it may be possible to move the crown more than the envelope implies.

For some patients, the distances in the guidelines can be exceeded, and for some, you would be hard pressed to move the teeth that far.

Question 12

What are the envelopes that surround teeth and affect what can be done to the?

Answer 12

The envelope of tooth movement which is influenced by bodily movement, tipping, intrusion, and extrusion.

The envelope of growth modification surrounds the tooth movement envelope.
It reflects the amount of change in tooth positions that can be achieved by changing the growth of the jaws.

The envelope of discrepancy which is the envelope of surgical change

Question 13

How does age affect the envelopes that surround teeth?

Answer 13

No growth modification in adults

Question 14

What are the health indications for surgical treatment?

Answer 14

Healthy patient: Pathological conditions must be under control but the patient doesn’t have to be in perfect health

Smoking reduces blood flow and healing.

Control periodontal disease

Mental and physical health should be good.

Question 15

For a patient with Class III malocclusion and reverse overjet, would successful treatment be possible by tipping the upper incisors tipped facially and retracting the lower incisors?

Answer 15

One limit would be how far the teeth could be moved, but there also is a limitation related to facial appearance. Retracting the lower incisors tends to make a prominent chin even more prominent, just the reverse of camouflage, so Class III camouflage can be done only for mild Class III problems.

Question 16

Can vertical problems be camouflaged?

Answer 16

Elongating teeth in a long face patient, even if the occlusion is corrected, is likely to make the patient look worse, not better. For that reason, surgery may be needed in long face patients even if the dental discrepancy is within the envelope of discrepancy.

Question 17

How is orthodontic camouflage outcomes judged?

Answer 17

Based on the aesthetic outcome

Question 18

Why would premolars be extracted from the lower arch when correcting class II?

Answer 18

If premolar extractions are done in the mandibular arch, it is to allow use of Class II elastics (from lower molars to upper incisors)

Question 19

When is it a bad idea to use class II elastics to repair class II malocclusion?

Answer 19

When there is also a vertical problem caused by excessive maxillary growth leading to downward and backward rotation of the mandible. Class II elastics would accenturate the vertical problem as a result.

Question 20

What orthodontic work is done following orthognathic surgery?

Answer 20

The stabilizing arch wires remain in place after surgery until healing is satisfactory and the patient is comfortable functioning inthe the spline that was used at surgery to establish the jaw relationship.

Light elastics are worn to control jaw movements and guide correct occlusion.

This usually takes place and appliances are removed 6 months after surgery.

Question 21

What treatments are done for patients with cleft lip and palate at each stage of a child’s life?

Answer 21

In infancy, dental specialist may do presurgical orthopaedics to align the maxillary cleft segments. Surgeon repairs lip and cleft palate +/- early bone graft. Social worker counsels parents on future care. Geneticist tests for syndromes in the child. Speech pathologist monitors speech development. Audiologist/ENT surgeon monitor middle ear function.

During preadolescent stage between 5 and 8 years old. The patient will have a bone graft placed in the alveolus - alveolar bone grafting. In conjunction with this there will be an initial phase of orthodontics to align the dentition and expand the maxillary arch.

Later during adolescence, there will be a second phase of orthodontics and patient may need orthognathic surgery after adolescent growth spurt.

Finally residual soft tissue deficiencies are fixed as well asymmetries of the lip and nasal regions.

Question 22

What is the sequence of cleft lip treatment?

Answer 22

either presurgical infant orthopedics or a lip adhesion may be recommended. Once the displaced cleft segments are repositioned, the surgeon can repair the lip under less tension.

Until 1 year old a feeding appliance MAY be used.

Repair of the cleft palate occurs between 1 - 2 years of age.

During preschool years child will attend regular team evaluations and may have other treatments such as general dental care and surgeries to improve function of soft palate, middle ear, and lips.

Orthodontic treatment + Alveolar bone graft will be placed approximately 6 - 8 years of age (exact time will be assessed) Bone graft is taken during mixed dentition stage near the cleft site.

Question 23

How is infant orthopaedics done for babies with unilateral and bilateral cleft lip and palate?

Answer 23

For the baby with a unilateral cleft lip and palate, an orthopedic appliance is used to mold and approximate the maxillary cleft segments decreasing the facial asymmetry.

For the baby with a bilateral cleft lip and palate, a similar appliance is used to expand the maxillary segments and to retract and approximate the premaxillary segment to a more normal position

Question 24

How commonly is infant orthopaedics used? What is used instead nowadays?

Answer 24

in 1965 - 80, infant ortho was very popular but it is now considered less useful than originally though and so it has been discontinued from most places.

Instead, lip adhesion is used which repairs the superficial skin tissues of the lip above the vermillion border.

Question 25

What is a feeding appliance and when is it used?

Answer 25

A full-coverage palatal acrylic plate that occludes the palatal cleft. It improves swallowing and allows more effective feeding in a baby.

They are used until 1 year old and have to be constantly replaced as the baby grows. This is because the cleft is repaired between 1 and 2 years of age.

Feeding appliances have not been demonstrated to be effective scientifically as of yet.

Question 26

Why is repair of the palate done between 1 and 2 years of age?

Answer 26

Exact timing is controversial because speech pathologist would prefer early but surgeon/orthodontist would prefer later until there is sufficient development and maturation of the hard tand soft tissues.

Question 27

How is repair of a cleft palate done surgically?

Answer 27

Lifting soft tissue flaps from the cleft halves of the palate and suturing the flaps in the midline to close the bony defect.

Question 28

Why shouldn’t maxillary expansion of cleft lip and palate patients be done at 3 - 5 years?

Answer 28

Generally, orthodontics at this age has little long-term effect and for that reason can be considered a waste of time and effort. It is better to wait until the mixed dentition, when the permanent incisors and first molars have erupted.

Question 29

Why is orthodontic treatment done alongside alveolar bone grafting at the same time?

Answer 29

To bring the incisors into position (often they are rotated when they erupt, due to stretching of the tissues during palate repair),

And, more important,, to prepare the maxillary arch for the alveolar bone graft.

Question 30

What problems are commonly associated with cleft lip and palate?

Answer 30

Posterior crossbite

Spacing/crowding

Skeletal problems of the long face and/or maxillary deficiency.

Question 31

What are the considerations that should be taken when timing the decision for treatment?

Answer 31

Effectiveness: How well does the treatment work? To what extent does it solve the patient’s problems? The more improvement it produces, and the more ideal the result, the more effective it is. Is effectiveness different at different stages of growth?

Efficiency: How much effort does it take to achieve a satsifactory result? How does the benefit of treatment relate to risk and cost? For equivalent results, the more it costs, the less efficient it is. Is efficiency different different at different stages of growth?

Question 32

What are the costs that should be considered when efficiency is evaluated?

Answer 32

The economic cost: Dollars which reflects time and effort for doctor and staff.

Burden of treatment: its impact on the patient and the parent.

Question 33

When should growth modification be timed?

Answer 33

Adolescent growth spurt

Completed by the time the growth spurt ends otherwise much of the effect can be lost to rebound growth.

Question 34

What happens if treatment for growth modification is done too early or too late?

Answer 34

If you start too late, it doesn’t work—you can’t modify growth that isn’t happening, and the treatment would not be effective.

If you start too soon, it takes too long—you can’t quit until the growth spurt ends. So even if the treatment were effective, it would not be efficient. Both the burden of treatment and the economic cost would be unnecessarily high

Question 35

Which principles affect the timing of treatment?

Answer 35

Growth modification is often desirable

Tooth eruption correlates with the skeletal growth status and timing of the adolescent growth spurt

Permanent teeth often do not erupt where their primary predecessors were

Question 36

How should orthodontic treatment referral timing be chosen for orthodontic treatment?

Answer 36

Using the physical maturation level rather than the dentition for class II and class III.

If the problem is only dental (Class I crowding) then judge by dentition.

Question 37

Why is the best time to treat most orthodontic problems the adolescent growth spurt?

Answer 37

The permanent teeth are available for final alignment.

Effective growth modification can be obtained if needed.

The treatment ends as adolescent growth slows to the low rate of later life (growth doesn’t totally stop-

Adults continue to grow, (very slowly).

One stage of treatment, rather than a first phase during the mixed dentition and a second phase later, gives a shorter treatment time and maximum efficiency.

Question 38

What is the major indication for delaying treatment until after adolescence?

Answer 38

Class III due to excessive mandibular growth

Question 39

How do class III patients differ from the norm?

Answer 39

Class III patients with excessive mandibular growth differ from the norm in two ways:

Their mandibles are large

Their mandibular growth doesn’t stop at the end of the adolescent growth spurt.

Question 40

When should maxillary expansion be timed?

Answer 40

If treatment started in the primary dentition it would have to continue through adolescence so early expansion isn’t a good idea.

Adolescence is the best time.

Question 41

How is maxillary expansion done in the primary dentition?

Answer 41

A jackscrew device is used but this is often unnecessary and risks injury to the patient.

Question 42

What are the steps in serial extraction?

Answer 42

Removal of primary canines to provide enough space for the permanent lateral incisors as they erupt.

Removal of the primary first molars before they would normally be lost, to encourage eruption of the first premolars

Extraction of the first premolars before the canines and second premolars erupt. Usually the second primary molars also are extracted at this point

Primary canine -> First primary molar -> first premolar.

Question 43

What are the problems of serial extraction?

Answer 43

2 main problems:

1) Accurate prediction that crowding is severe. If wrong a mistake is irreversible and can be a huge problem
2) 2nd phase of treatment is often needed after permanent teeth erupt.

Question 44

What are the advantages of serial extractions?

Answer 44

If a child is severely crowded, it:

Eliminates incisor crowding during the mixed dentition, which can make the parent and child happier during that period.

Reduces phase 2 treatment time

Reduces chance that crowded-out canines will erupt through mucosa instead of gingiva (better long term perio health)

May also improve long term stability

Question 45

Who should get serial extractions?

Answer 45

Modern guidelines restrict serial extractions to children with:

10mm or more crowding in both arches predicted by space analysis

Normal facial proportions (not skeletal class II/III, short/long face)

Phase 2 treatment definitely available

Question 46

How should class I patients with severe crowding be treated?

Answer 46

Unless crowding is VERY severe, don’t extract primary mandibular canines prematurely.

Question 47

How should patients that lose a primary canine spontaneously be treated?

Answer 47

If one or both primary canines are lost spontaneously as the lateral incisors erupt, some early treatment is indicated:
Keep it symmetric: extract the other primary canine if only one was lost.
Use a lingual arch to maintain space unless the strict criteria for serial extraction are met.

Question 48

Why is growth modification often done in early age?

Answer 48

The major reason for it is to modify growth. Tooth movement can and should be done later.

Growth modification at an early age tends to wear off as uncontrolled later growth occurs, so what looked successful in the short term may not be so successful in the long term.

Question 49

Describe the UNC clinical trial in the late 1990s and the results:

Answer 49

PHASE 1:

3 groups: No treatment until adolescence, headgear treatment, and functional appliance treatment. All children received comprehensive treatment following phase 1 treatment.

Progress records @ 15 months in phase 1. ANB angle used to measure the discrepancy.

Groups that were treated had significantly different jaw growth to controls.

Variable effectiveness but 75% saw little or large improvement.

CONCLUSION: Early treatment is effective but not 100% of the time.

PHASE 2:

Dental occlusion, jaw relationship, type of treatment needed in phase2, and treatment time were evaluated in order to understand if early treatment produced a better result at the end of phase 2.

PAR scores were measured to evaluate overjet, overbite, midline, alignment of maxillary and mandibular teeth, and buccal occlusion on RHS and LHS. Lower the PAR score the better the result. 5 or lower = perfect dental occlusion.

CONCLUSION: Early treatment made very little long-term difference in jaw relationships. At the end of phase 2, the differences between the children who had two phases of treatment and those who had only one were no longer statistically significant. 2 phase treatment is not supported by evidence.

Question 50

Is 2 phase treatment ineffective for all skeletal problems?

Answer 50

For patients with class II problems, a first phase treatment prior to adolescence is less efficient and not more effective than later treatment.

Children with severe skeletal vertical problems were not included in the clinical trial so data doesn’t really apply to them.

Question 51

When should class II patients be treated with preadolescent treatment?

Answer 51

Evidence of major social problems from teasing

Evidence of damage to teeth or soft tissues related to malocclusion.

Question 52

Class III background concepts:

Answer 52

Excessive mandibular growth is almost impossible to control. Mandibular restraining devices arent very effective in most circumstances and children will not tolerate the amount of force required.

Deficient maxillary growth can be stimulated with force to pull the maxilla forward but for face mask should be done around age 8 or 9 and for TAD around age 10.5 or 11.

Question 53

Does effectiveness of the facemask in children mean all Class III children should have face mask treatment early?

Answer 53

No, only those whose problem is largely due to maxillary deficiency and who would prefer face mask treatment to bone plates that would require (relatively minor) surgery to place them.

Question 54

How do TADs work in correcting class III? How effective are they?

Answer 54

Bone plates in the maxilla at the base of the zygomatic arches that are held by 3 screws, and bone plates mesial and inferior to the mandibular canines that are held by 2 screws (see Level III,

On average, about twice as much maxillary advancement is obtained as with a face mask, even if the force from the face mask is applied to bone screws in the anterior maxilla

Question 55

What’s the best time to use TADs with class III elastics?

Answer 55

As early as possible, which turns out age 10 1/2 to 11, significantly later than the age for face mask treatment.

Question 56

At what age is a patient too old to expect a favorable response to TADs with class III elastics?

Answer 56

It appears that significant advancement of the maxilla is less likely after age 12 or 13, depending on the patient’s maturity. Since the response does include a component of restraint of mandibular growth, it is possible that this might, for the first time, be a way to control excessive growth during adolescence–but that has not yet been demonstrated in enough patients to be sure it would work.

Question 57

What should you recommend to the parents of the Class III child in your practice?

Answer 57

Child should have early ortho evaluation (lat cephs for superimposition)

Early referral means age 7/8, if possible; earlier

If excessive mandible growth is the problem: Ortho and surgical treatment should be after adolescent growth spurt.

If maxillary deficiency: Facemask in young children (8yos), TADs in older children (10.5/11 yos)

Ensure parents know this can recur.

Question 58

When is the best time for orthodontic treatment?

Answer 58

The best time for most orthodontic treatment is during the adolescent growth spurt, which usually coincides with the transition from the late mixed dentition to the early permanent dentition.

Question 59

When is early treatment of class I problems indicated?

Answer 59

Very severe crowding

Early loss of primary teeth, especially primary canines

Question 60

When is early treatment of class II problems indicated?

Answer 60

Psychologic problems produced by teasing, etc.

Trauma to the soft tissues or teeth during function (usually from deep overbite)