Ortho level 3 unit B module 3 and 4

Question 1

When is adjunctive treatment used in orthodontics?

Answer 1

Although adjunctive treatment could be needed in children, for all practical purposes it is treatment for adults who have lost teeth and/or supporting bone to dental disease.

Question 2

What is pathologic occlusion?

Answer 2

Some tooth positions and dental relationships are not conducive to long-term oral health, so that occlusal function contributes to destruction of the occlusion.

An example would be the loss of gingival tissues lingual to the upper incisors from a deep, impinging overbite.

Question 3

What should be done for pathologic occlusion?

Answer 3

If signs of pathologic occlusion exist, or if restorations needed for other problems would compromise the maintenance of oral hygiene or overly stress the periodontal support apparatus, tooth movement should become part of an overall treatment plan.

Question 4

What are the goals of adjunctive treatment?

Answer 4

The goals of adjunctive treatment are to:

Facilitate restorative treatment by positioning the teeth so more ideal and conservative techniques (including implants) can be used.

Improve periodontal health by eliminating plaque-harboring areas and improving the alveolar ridge contour adjacent to the teeth.

Establish favourable crown-root ratios and position the teeth so that occlusal forces are transmitted along the long axes of the teeth.

Do this while maintaining or improving dental and facial aesthetics.

Question 5

What are the possible tooth movements in adjunctive treatment?

Answer 5

Mesial or distal movements of specific crowns, roots, or both

Correction of the axial inclination of drifted teeth

Correction of the buccolingual position of certain teeth

Correction of rotations
extrusion of selected teeth

Question 6

How are teeth with excessive elongation treated?

Answer 6

As a general rule for adjunctive treatment, teeth that are excessively elongated are best treated by reduction of crown height, which has the added advantage of improving the crown-root ratio in patients who have experienced loss of alveolar bone.

Question 7

Why should intrusion be avoided in adjunctive orthodontic treatment?

Answer 7

Although intrusion of teeth can be an important part of comprehensive treatment for adults, it should be avoided as part of adjunctive treatment because of its technical difficulty and the possibility of root resorption and/or loss of control of tooth positions.

Question 8

What are the diagnostic steps of creating a treatment plan for adjunctive orthodontic treatment?

Answer 8

Collecting an adequate data base of information

Developing a comprehensive but clearly stated list of the patient’s problems

Question 9

What diagnostic information is required when providing adjunctive orthodontic treatment to patients with periodontitis?

Answer 9

OPG + Intraoral radiographs

Articulator mounted casts are more likely to be needed than cephalometric radiographs

Question 10

What guides treatment planning of orthodontic treatment?

Answer 10

The sequence of treatment is guided by two principles:

Pathologic problems must be brought under control before the orthodontic phase of treatment begins.

Permanent restorations and definitive perio procedures should be deferred until after the final occlusion has been developed.

Question 11

What are the steps in treatment planning of adjunctive orthodontic treatment?

Answer 11

The first step in treatment planning, therefore, is to separate pathologic problems from occlusal problems.

Once these problems have been identified, they are brought under control. The sequence of treatment then is orthodontic tooth movement to establish the occlusion and finally the definitive perio/restorative treatment. Maintenance of the restorations and continued disease control is required long term.

Question 12

How is the diagnostic database derived?

Answer 12

Interview

Clinical examination

Analysis of diagnostic records (eg dental casts)

Question 13

How does treatment differ in reduced periodontal support?

Answer 13

Decrease in volume of PDL. More pressure on the remaining PDL so lighter forces required when bone loss has occurred.

Center of resistance lower down away from the crown. (larger moments needed to control root position)

Question 14

Can you use a removable appliance for adjunctive orthodontics, or is a fixed appliance required? Why or why not?

Answer 14

For adults receiving adjunctive orthodontics, as a general rule, removable appliances rarely are satisfactory. 4 reasons for this:

It is impossible to obtain both a force, which generates a moment, and the moment of a couple to counteract the moment of the force, with a single spring. (Root position will change)

It is difficult to correct rotations at the same time a crown is repositioned, for the same reasons: two points of contact are needed to rotate a tooth without displacing it

At best, the removable appliance is worn only part of the time. Interrupted forces, those that are there when the appliance is in place but drop to zero when it is removed, can move teeth but are not as effective as continuous forces.

Discomfort and interference with speech and mastication are greater than with a carefully designed and placed fixed appliance.

Question 15

When can a removable appliance be used for adjunctive orthodontic treatment?

Answer 15

One situation in which an acrylic removable appliance may have an advantage is in a patient with multiple missing teeth. With a fixed appliance that has long unsupported spans of wire between teeth, distortion of the arch wire can become a problem, and irritation of the cheek can also occur. These problems are avoided with a removable appliance that has acrylic between separated teeth.

some reaction forces from tooth movement can be spread over adjacent supporting tissues, such as the palatal vault and alveolar mucosa. Major tooth movements, however, will still be very difficult with a removable appliance. The anchorage value of supporting tissues is minimal.

Question 16

How should brackets be placed to upright a leaning molar?

Answer 16

Often the primary goal of adjunctive treatment is to upright a molar, using the premolars and canine as anchorage. If the anchor teeth are not perfectly aligned, and brackets are placed on the anchor teeth in the ideal position near the center of the crown, a straight piece of wire connecting the brackets creates forces and moments to ideally position these teeth, which can decrease their anchorage value

If the goal is to upright a molar but to use the premolars and canines just as anchorage without repositioning them, it would be better to place the brackets on the anchor teeth so that a straight segment of wire would not displace them

Question 17

Why are periodontal problems on the mesial of a tipped tooth common?

Answer 17

Periodontal problems on the mesial of a tipped mandibular second molar occur for two reasons: (1) the area beneath the tipped mesial portion of the crown is difficult to clean and inherently unhealthy, and (2) occlusal forces are not directed along the long axis of the tooth.

Question 18

What are the advantages of uprighting a tipped molar and closing the spaces between premolars on periodontal health?

Answer 18

The advantages of uprighting the tipped molar and closing spaces between the premolars are better periodontal health and a better long-term prognosis for restorations placed in this area. It is possible to fabricate a bridge without uprighting a tipped abutment molar, but it is very difficult to make a good one.

The long-term success of an implant-supported crown adjacent to a tipped molar also can be compromised.

Question 19

What is the best treatment for uprighting a mandibular second molar that has tipped mesially into space of mandibular first molar?

Answer 19

When a mandibular second molar has tipped mesially into an old first molar extraction space, the best treatment usually is to extract the third molar and upright the second molar by tipping it distally. This provides space for an appropriately contoured replacement tooth and places occlusal forces more along the long axis of the teeth.

If restorations (crowns/onlays) are needed in what would be the bridge abutment teeth (as they often are), replacing the missing first molar with a bridge pontic can be the best procedure (see images). If restorations are not needed, an implant is often preferred.

Question 20

What should be considered when uprighting second mandibular molars that have drifted mesially?

Answer 20

Extraction of the third molar is necessary if significant distal movement of the second molar is to be obtained. If both the second and third molars are to be retained, the technique for uprighting is different

Adequate anchorage for the uprighting must be obtained. This means that fixed attachments on the molar, canine, and both premolars are necessary, and better control is obtained when a fixed lingual arch from canine to canine is placed

Reduction of the occlusal surface of the molar is necessary as it uprights, to control occlusal interferences

Question 21

What are the steps of mandibular molar uprighting?

Answer 21

Step 1 is to place a fixed appliance on the molar and the anchor tooth. A bonded bracket on the molars and canines are almost always preferred.

Step 2 is to further open the space of the missing first molar, closing any space between the premolars and moving the second molar more distally. Often it is as important to move the second premolar mesially, closing spaces between the premolars, as it is to move the molar further distally.

Step 3 is using a fixed retainer to maintain tooth position until a bridge or implant is placed. Try get the bridge or implant in asap after orthodontic treatment.

Question 22

How can the mandibular molar be uprighted while correcting malalignment of the premolars and canines at the same time?

Answer 22

A flexible rectangular wire placed in both the premolar brackets and the molar tube.

A continuous wire that spans the old extraction site and an auxiliary spring. This requires two tubes on the molar, one used for the auxiliary spring and the other for the main arch wire. It is convenient to have two tubes available routinely on a molar to be uprighted, so that an auxiliary spring can be used if desired.

A wire in the brackets of the anchor teeth that does not span the old extraction site, and an auxiliary uprighting spring

Choice is determined by how much change is desired

Question 23

When should an auxiliary spring with a separate anchor segment of rigid wire be used?

Answer 23

An auxiliary spring with a separate anchor segment of rigid wire is indicated when the molar is severely tipped, so that a continuous flexible wire cannot be fitted into both the attachments on the anchor teeth and the molar tube.

With this approach, the anchor teeth should be stabilized with a rigid wire before the auxiliary spring is activated.

Question 24

How is the space of the mandibular first molar uprighting expanded?

Answer 24

Using a compressed coil spring over a rigid wire. Wire musn’t be too tight in the brackets because we need sliding to occur.

Question 25

How much clearance is needed for sliding?

Answer 25

For sliding to occur, there must be a 0.002 inch clearance.

Question 26

How can the spring be reactivated?

Answer 26

By adding a split section of tubing over the arch wire to compress the spring forcing it to expand.

Question 27

How can mandibular molar be moved mesially?

Answer 27

A T-loop can be used in a rectangular arch wire segment.

When it is placed into the molar tube, a moment is created to tip the crown distally and bring the root mesially

If the wire is pulled through the distal of the tube and bent over. the effect is to create a force to prevent the crown from tipping distally. (premolars are tied together for adequate anchorage)

If the molar to be uprighted is severely rotated and tipped, a modification of a loop wire, with the wire inserted into the distal of the molar tube can be helpful

Question 28

When is mesial root movement needed?

Answer 28

It is much more difficult to move the root of the second molar mesially than to tip the crown distally, but if the third molar is not extracted, some mesial root movement is needed.

Question 29

How is maxillary molar uprighting different to mandibular molar uprighting?

Answer 29

The additional anchorage of a canine-to-canine lingual arch is not needed

As they drift mesially, upper molars tend to tip less than lower molars but rotate more.

Question 30

What kind of retainers are indicated following molar uprighting?

Answer 30

Fixed retainers, retainers of this type are tolerated by patients much better than a palate-covering maxillary removable retainer, and for that reason are much more effective in maintaining the position of the teeth until final restorations can be placed.

Question 31

Why is closing space in the upper arch more feasible than the lower arch?

Answer 31

Because research has shown that in the upper arch, healthy alveolar bone can exist even if the second molar and second premolar roots are not parallel,

The space can be closed without the necessity of paralleling the roots.

Question 32

How can a posterior crossbite be corrected?

Answer 32

a rubber band from a button on the lingual of the lower molar to a hook on the facial of the upper molar can be used to tip the upper molar lingually and the lower molar facially.

Question 33

When is a canine to canine lingual wire indicated?

Answer 33

in the mandibular arch, a bonded canine-to-canine lingual wire increases the anchorage value of a premolars-canine anchorage unit–but this is rarely indicated in the maxillary arch

Question 34

How is a molar uprighted if not severely tipped and if severely tipped?

Answer 34

If a molar to be uprighted is not severely tipped, a continuous flexible archwire segment (usually NiTi wire) is effective

Greater tipping of the molar usually is managed best with the use of an auxiliary uprighting spring

Question 35

When should crossbite correction be done? What is needed after?

Answer 35

Crossbite correction with cross-elastics can be done simultaneously with uprighting, but long-term retention is likely to be needed–and a fixed bridge with two abutments is a permanent retainer

Question 36

How can mesial root movement be achieved?

Answer 36

Mesial root movement to close space can be managed with a T-loop archwire segment, and is easier to accomplish in the maxillary arch, where root inclination is not as critical as in the mandibular arch

Question 37

How should a tooth be treated if it has a defect in the cervical third of the root?

Answer 37

If a tooth has a defect in the cervical third of the root (from fracture, resorption, decay or periodontal problems), extensive crown lengthening would be necessary to gain access for treatment. Poor esthetics and adverse changes in the crown-root ratio are likely problems.

Question 38

How can orthodontics help with teeth that have a defect in the cervical third of the root?

Answer 38

For many patients, controlled extrusion (forced eruption) is an excellent alternative. It improves endodontic access and can allow crown margins to be placed on sound tooth structure while maintaining the gingival contour. Although a tooth with a single tapering root is the ideal candidate for extrusion, multirooted teeth also can be managed in this way.

Question 39

What determines the distance of extrusion?

Answer 39

The distance of extrusion is determined by

the location of the defect relative to the alveolar crest
space for placement of the restoration margin (1 mm)
allowance for the gingival attachment (2 mm)

Question 40

How long should an extruded tooth be held in place for?

Answer 40

An extruded tooth should be held in its new position at least 4 weeks, until the rebound tendency from stretched gingival and periodontal tissues subsides

Question 41

What are the limitations to using interarch elastics for extrusion?

Answer 41

The force from an interarch elastic is not as constant as from a spring on a fixed appliance. Anything about an orthodontic appliance that can be removed will be—the elastic will not be worn all the time, even by a highly cooperative patient. So the rate of extrusion is less predicable with this method, but it can work very well for a fractured molar.

Question 42

How can eruption be forced to maintain bridge abutment tooth?

Answer 42

Section bridge and remove crown from the damaged abutment.

Extrude using other teeth as anchorage.

Question 43

Summary of forced eruption:

Answer 43

Is indicated as a way to make restoration of fractured teeth possible

Usually requires a partial fixed appliance (an exception using magnets in attraction can be seen in

Should be done using relatively light force (50-100 gm)

Occurs at a rate of about 1 mm per week

Often requires recontouring the gingiva, and sometimes requires recontouring alveolar bone, after the tooth movement is completed.

Question 44

How can maxillary incisor aligment be done?

Answer 44

There are two ways to accomplish this:

bonded brackets, flexible arch wires, and coil springs over the wire to reposition the teeth.

Or a series of transparent plastic aligners

Question 45

What kind of retainers can be used to hold central incisors together?

Answer 45

There are two ways to make a fixed retainer to hold central incisors together. The first type, consisting of a rigid bar, is both less effective (more likely to break) and less physiologic (splints the teeth too much).

The better way, bonding the teeth together with a piece of flexible wire

Question 46

Are plastic aligners useful for closing up space between maxillary incisors?

Answer 46

This approach is less effective when space closure is needed. It is better suited for the correction of mild crowding.

Question 47

How are plastic aligners made?

Answer 47

These aligners are made on a series of computer-generated casts, with a small amount of movement of teeth (not more than 0.5-mm increments) between aligners. Each aligner is worn for approximately 2 weeks, then is replaced with the next in a series.

Question 48

If there is excessive mandibular incisor crowding is it better to extract an incisor then align or align immediately?

Answer 48

From the perspective of dental esthetics, three lower incisors versus four is not an important issue, but the lower incisors are exposed more in older patients than in younger ones because the upper and lower lips sag downward with aging. So alignment of these teeth can become more important with increasing age.

In addition, in adults, loss of lip support if the incisors are retracted during space closure can increase facial wrinkles and subtly make the patient look older. For esthetics, it’s better to increase lip support than decrease it. Because of the esthetic sensitivity, mandibular incisor alignment can be considered the most difficult and potentially troublesome type of adjunctive treatment.

Question 49

Conclusions about mandibular incisor alignment:

Answer 49

Mandibular incisor alignment in adults:

is one of the more difficult adjunctive treatment procedures.
in a patient with severe incisor crowding and a fractured or endodontically-involved incisor, extraction and space closure can be the most effective treatment.
non-extraction alignment of less severely crowded lower incisors often requires repositioning of the upper incisors as well,
whatever the type of treatment in an adult, long-term retention will be needed. Initially, a suckdown retainer can be satisfactory; in the long-term, either a clip-on removable retainer or a bonded lingual flexible wire performs better