Spring - Final Flashcards
(205 cards)
1
Q
What are the three main treatment options for phase I maxillary crowding?
A
- Expansion
- Limited orthodontics on maxillary first molars and incisors
- Extraction of primary canines (or others as needed) to create space for erupting permanent teeth
This test is crazy!
2
Q
What are the major reasons to do early maxillary expansion in the mixed dentition?
A
- To eliminate mandibular shifts on closure
- To provide more space for the erupting maxillary teeth
- To lessen dental arch distortion and potential tooth abrasion from interferences of anterior teeth
- Reduce the possibility of mandibular skeletal asymmetry
3
Q
What are the characteristics of indentations in the superior surface of the tongue?
A
W-arches, quad helixes, expanders, and habit appliances can leaven indentations on the tongue, and they often remain after appliance removal for up to 1 year. No treatment is recommended but parents and patients should be aware.
4
Q
What are the possible treatment options for phase I mandibular crowding?
A
- Expansion (only dental expansion, not skeletal) with a schwartz, or lip bumper
- Limited ortho on mandibular permanent teeth
- Extraction of primary canines (or others as needed) to create space for erupting permanent teeth
5
Q
What are the characteristics of treating class III skeletal growth patterns in phase I ortho treatment.
A
– The early you get started with these patients, the better.
– Patients are typically in an anterior crossbite with maxillary constriction and can be in full posterior cross bite
– Class III growth patterns are very difficult to control, especially in males, and referral to an orthodontist should be initiated as soon as possible
– Treatment for these patients typically consists of limited orthodontic treatment on the permanent dentition in association with expansion and reverse pull head gear.
– If forward traction is applied at an early age, it is possible to produce forward displacement of the maxilla rather than just displacement of maxillary teeth
6
Q
What are the characteristics of treating class II skeletal growth patterns in phase I ortho treatment?
A
-- Unless they have another problem that can be treated in phase I, like mandibular crowding, just wait to do one full treatment later on instead of in two phases if they have class II skeletal growth. • Unlike early treatment for a skeletal class III patient, phase I treatment for a skeletal class II patient is not as common. • A lot of research has been done comparing children who have undergone phase 1 growth modification for class II skeletal growth, and the following has been concluded about the early attempts and the benefits of early treatment for class II problems. – Skeletal changes are likely to be produced by early treatment with head gear or a functional appliance but tend to be diminished or eliminated by subsequent growth and later treatment -- Skeletal changes account for only a portion of the treatment effect, even when an effort is made to minimize tooth movement – After later comprehensive treatment, alignment and occlusio are very similar in children who did and those that did not have early treatment – Early treatment does not reduce the number of children who require extractions during a second phase of treatment or the number who eventually require orthognathic surgery – The duration of phase II treatment (full ortho treatment) is quite similar in those who had a first phase of early treatment aimed at growth modification and those that did not • Based on these results, it seems clear that for most class II children, early treatment is no more effective than just one phase of later treatment
7
Q
What are the characteristics of permanent first molars erupting ectopically?
A
• Moderately advanced resorption of the primary second molar, from ectopic eruption of the permanent maxillary first molar requires active intervention.
• In these x-rays the distal root of the primary maxillary second molar shows enough resorption that self- correction is highly unlikely.
• Sometimes a spacer can be placed between the teeth to distalize the first molar other times active orthodontic treatment must be performed to distalize the tooth
• Due to the resorption of the distal root of the primary tooth, it is often necessary to extract the primary second molar.
– Space maintenance should be incorporated into the treatment plan.
8
Q
The permanent incisor tooth buds are positioned buccally to the primary incisors. True or False?
A
False, lingually
9
Q
Lingual arches should not be placed until after the lower incisors erupt. True or False?
A
True, because of the ectopic eruption that can happen lingually and tooth buds that are found lingually
10
Q
What is tooth fusion?
A
• Tooth Fusion is when two tooth buds fuse together to make one large wide crown. The fused tooth will have two independent pulp chambers and root canals. The fusion will start at the top of the crown and travel possibly to the apex of the root. So you are missing one tooth when you count all the teeth.
11
Q
What is tooth gemination?
A
• Tooth Gemination is when one tooth bud tries to divide into two teeth. The tooth count is normal with gemination. On a radiograph, the geminated tooth will have one pulp canal but two pulp chambers.
12
Q
Treatment options for fused or gemination teeth are usually not good. True or False?
A
True. The teeth typically are extracted but sometimes can have RCT and then the crowns can be re-contoured.
– Restore fused tooth with RCT
– Extraction with implant replacement
– Autotransplantation
– Orthodontic space closure and substitution
13
Q
Early loss of a primary tooth presents a potential alignment problem because drift of permanent or other primary teeth is very likely unless it is prevented. True or False?
A
True
14
Q
Space maintenance is always appropriate. True or False?
A
False. Only when adequate space is available, and when all unerupted teeth are normal and at the normal stage of development. If there is not enough space for the permanent tooth or if the permanent tooth is missing, space maintenance alone is inadequate or inappropriate and other treatment approaches are necessary. If a space maintainer is used it must be monitored carefully for breakage and leakage to be successful.
15
Q
If a permanent successor will erupt within 6 months (ie: there is more than one-half to two-thirds of its root formed), a space maintainer is unnecessary. True or False?
A
True
16
Q
What are the characteristics of a band and loop space maintainer?
A
– Band and loop–Because the loop has limited strength, this appliance must be restricted to holding the space of one tooth and is not intended to accept the functional forces of chewing
• Should you solder a loop to a stainless steel crown? No, ideally no.
• Should you band the primary or permanent tooth?
– Risk of decay to permanent tooth
– Evaluate x-ray to evaluate when the
primary tooth will be lost
• If a single primary molar has been lost bilaterally, a pair of band and loop space maintainers is recommended instead of the lingual arch that would be used if the patient were older because the primary incisors often erupt lingually, which would interferer with their eruption.
• Band and loop survival is not impressive and has been judged to be about 18 months with cement failure being the most frequent problem
17
Q
What are the characteristics of distal shoe space maintainers?
A
– Distal Shoe
- The distal-shoe space maintainer is indicated when a primary second molar is lost before eruption of the permanent first molar and is usually placed at or very soon after the extraction of the primary molar.
- The loop portion, made of 36 mil stainless steel wire, and the intra-alveolar blade are soldered to a band so the whole appliance can be removed and replaced with another space maintainer after the permanent molar erupts
- The loop portion must be contoured closely to the ridge since the appliance cannot resist excessive occlusal forces from the opposing teeth.
- The blade portion must be positioned so that it extends approximately 1 mm below the mesial marginal ridge of the erupting permanent tooth to guide its eruption. This position can be measured from pretreatment radiographs and verified by a radiograph taken at try-in or post- cementation.
- An additional occlusal radiograph can be obtained if the faciolingual position is in doubt.
18
Q
What are the characteristics of lingual arch space maintainers?
A
– Lingual arch - A lingual holding arch usually is the best choice to maintain space for premolars after premature loss of the primary molars when the permanent incisors have erupted.
– The lingual arch is stepped away from the premolars to allow their eruption without interference, which results in a keyhole design. The wire is also 1.5 mm away from the soft tissue at all points.
– A lingual arch on the maxillary teeth can be used if the overbite is not excessive
– A spur on a lingual arch can be used in the mixed dentition either to maintain a correct midline when a primary canine is lost or to retain a corrected midline.
19
Q
What are the characteristics of a nance space maintainer? When is it indicated?
A
- Nance - a Nance arch with an acrylic button in the palatal vault is indicated if the overbite is excessive. The palatal button must be monitored because it may cause soft tissue irritation.
20
Q
What are the characteristics of a transpalatal arch space maintainer?
A
Transpalatal arch - The transpalatal arch prevents a molar from rotating mesially into a primary molar extraction space, and this largely prevents its mesial migration. Several teeth should be present on at least one side of the arch when a transpalatal design is employed as a sole space maintainer.
21
Q
What are the characteristics of removable space maintainers?
A
– Removable retainers • Removable hawley (wire labial bow) retainer with tooth • Removable essix with tooth • Removable partial denture - In a young child, a removable partial denture is used to replace anterior teeth for esthetics. At the same time, it can maintain the space of one or more prematurely lost primary molars. For this patient, the four incisors are replaced by the partial denture. Multiple clasps, preferably Adams’ clasps, are necessary for good retention. Both the clasps and the acrylic need frequent adjustment to prevent interference with physiologic adjustment of primary teeth during eruption of permanent teeth
22
Q
Premolars are the teeth most often extracted due to ortho treatment, but any tooth, or combination, could be used. True or False?
A
True
23
Q
What did Edward Angle believe?
A
Extraction for ortho treatment is almost a crime, called people that did it odontocides. Taught that bone could be induced by mechanical means to grow beyond its inherent size. Calvin Case taught the opposite, and that there are indications for extractions in certain forms of malocclusion.
24
Q
What is Charles Tweed’s story?
A
Tweed trained under Angle, but had also read Case’s articles, and was bugged by his bad cases where he didn’t extract any teeth. He re-did some and found that extractions can be beneficial. This was in the 1950’s.
25
What are the things to consider in patients with severe dental crowding?
1. Esthetic considerations (lip support)
2. Stability considerations (bony support, equilibrium of forces of soft tissues)
3. Gingival, bone and tooth health
26
What are the mm rules for arch length discrepancy and extraction requirement?
- Arch length discrepancy of less than 4 mm = extraction is rarely indicated
- Arch length discrepancy of 5 mm to 9 mm = extraction or non-extraction treatment is a possibility
- Arch length discrepancy of 10 mm or more = extraction is almost always required
27
What is bi-maxillary protrusion?
• Bi-maxillary protrusion refers to a protrusive dento- alveolar position of the maxillary and mandibular dental arches that produces a convex facial profile.
- Patients with this can have all four first premolars extracted to retract the protrusive incisors and allow the lips to relax and gently come together
28
When adult teeth erupt, they tend to erupt with a distal migration. True or False?
False. A mesial migration.
29
What is the concept of serial extraction?
- It was kjellgren in 1929 who coined the term Serial extraction to describe a procedure where some deciduous teeth were extracted and followed by extraction of permanent teeth to guide the rest of the teeth into normal occlusion.
- -The primary 1st molar is extracted, which then helps the first premolars erupt, and then you extract them as well
30
What are the main assumed disadvantages of extraction treatment in orthodontics?
- Non-extraction treatment is held by some to always be better than extraction.
- Non-extraction treatment is thought to improve the facial profile and appearance of orthodontic patients.
- Claims of detrimental facial appearance due to extraction include:
– Flat lips and retracted sunken in incisors
• If the anterior teeth are retracted to closet he extraction space, lip support is lost and can create a flattening of the lips and a sunken in incisor look.
– Narrow arch widths with large buccal corridors.
• It is believed that if you extract teeth then the dental arches must be constricted, which can create large buccal corridors.
31
What three main factors affect facial appearance?
1. Genetic Makeup
2. Environmental influences
3. Cultural background
32
What did the North Carolina study conclude about the attractiveness of extraction vs non extraction patients?
They concluded that there was no difference in attractiveness between extraction and nonextraction patients.
• It was concluded that extraction had a positive effect on the profile of patients with some combination of crowded and proclined teeth,
• Whereas nonextraction therapy had a detrimental effect on the profile
– This patient didn’t like the angulation and protrusion of her front teeth which caused the patient to have to strain to get her lips to touch.
• You can see the dimpling of the patients chin referred to as mentalis strain with lip incompetence.
– The patient was treated with non extraction therapy as a teenager and was never happy with the results.
– After consultation and analysis the patient decided to have four premolars extracted, to relax the lip incompetency and retract the incisor position.
33
How does proclining the mandibular incisors during treatment affect the periodontal status?
– Proclining the mandibular incisors more than 95° with decreased gingival thickness of less than .5 mm increased the severity and the amount of recession.
– This is a significant disadvantage for nonextraction patients with crowded mandibular incisors.
34
It now is claimed that expansion of the mandibular arch is stable if the maxillary arch is expanded, but no evidence supports this. True or False?
True
35
For the best treatment outcomes, some patients need non- extraction treatment, some need extractions, and a key goal of diagnosis is gathering data on which to base this decision, not on which bracket to use. True or False?
True
36
What are the characteristics of lower incisor extractions?
• Sometimes an orthodontist will order the extraction of a lower incisor.
• This is typically due to a tooth size discrepancy
• This treatment option is sometimes elected if an adult has mandibular incisor crowding with recession and bone loss on a protrusive incisor.
• Draw backs to lower incisor extraction treatment:
– Patient will have to be finished with a deeper bite (over-bite).
– Patient often will have some over-jet once the case is finished.
– Canine guidance is sometimes difficult to achieve.
• A full orthodontic work up and analysis must be performed, weighing the pros and cons before extraction of any tooth, especially a lower incisor due to the typical compromised results.
37
When are second molar extractions used?
With class II cusp and jaw relationships, anterior open bites, and severe thumb-sucking habits.
38
ANY tooth could be extracted for orthodontic purposes. True or False?
True
39
What is root burial?
• Because erupting teeth bring bone with it, orthodontic tooth movement can be used to create the alveolar bone needed to support an implant to replace a congenitally missing tooth.
– Missing maxillary lateral incisors or mandibular second premolars
• Root Burial is leaving a tooth in place, or its root, to help maintain bone in the area until an implant can be placed
40
Why is the mesial drift of a canine with a missing lateral incisor beneficial?
Because it will bring alveolar bone with it. • Once the canine has fully erupted:
– it can then be distalized orthodontically, into its proper position. Leaving a good bony site for a future implant.
– Or left in place and lateralized to replace the missing lateral incisor.
41
Canine substitution typically has the best results when only one canine is used to substitute for the missing lateral incisors, to help maintain arch width and length. True or False?
False.
- Canine substitution typically has the best results when both canines are used to substitute for the missing lateral incisors, to help maintain smile symmetry
42
What are the characteristics of replacing missing maxillary lateral incisors with implants?
* If implants are to be used to replace the missing lateral incisors it is advantageous to allow the maxillary canine to erupt into the lateral incisor position and then orthodontically distalize the canines, which increases the bone in the lateral incisor area for the future implant
* Missing lateral incisors must have the spaces maintained until implants can be placed once growth is completed.
* Retainer to replace missing teeth
* Bridges
* Maryland bridge
* Tooth bonded to permanent retainer
* Composite bridge
43
How are missing mandibular second premolars most often fixed?
• Close space orthodontically
– Temporary anchorage device (TAD)
• Bridges
• Implants
– Retention until implant can be placed
-If they don't have a lower wisdom tooth, then it wouldn't be ideal to bring all of the molars mesial.
44
When treating peg laterals, orthodontics should center the peg lateral. True or False?
True
45
When re-building a peg lateral, how large should it be?
* Measure the opposite side lateral incisor, if the tooth is present to determine size and shape
* If both lateral incisors are missing, the width is determined by using 2/3 size of the central incisor as a guide.
* The length should be 80 percent the length of the central incisor
* Gingival height of the lateral should be 1mm lower than the gingival height of the central incisor and canines.
46
Maxillary lateral incisors are the second most commonly impacted or displaced tooth behind the third molars. True or False? And what are the percentages?
False, it is maxillary canines.
• Impaction occurs in about 0.8 to 2.4 percent of the U.S. population and is significantly more common in females than males (about 2:1)
• In more than 90 percent of the cases impaction usually involves a single maxillary canine, however impactions are also seen bilaterally in 8 percent of the patients.
• The majority of impacted canines are displaced toward the palatal aspect, but 20 percent occur toward the facial aspect.
47
What are the main six reasons for maxillary canine impaction?
1. Crowding
2. Narrow maxillary arch
3. A class II division II incisor relationship
4. Familial tendency, some patients are genetically predisposed
5. Follicular disturbance of the canine
6. Pathology to the overlying primary dentition
48
For impacted canines, If the patient is not going to undergo orthodontic treatment to correct the tooth, it is best to extract the impacted tooth to reduce the risk of future pathological or trauma to adjacent teeth. True or False?
True. An implant with a crown or bridge can be used to replace the missing tooth.
49
If the canines are not overlapping the lateral incisors but are erupting mesially, pushing on the lateral incisors root, tipping the root mesially, what are the steps being evaluated and prescribed by the orthodontist to try to help the eruption path of the maxillary canines?
1. Extraction of the maxillary deciduous canine. This removes a possible overlying obstruction and creates a void in the bone, which activates the inflammatory response in the area. Like a corticotomy, removal of the primary tooth increases cellular differentiation and bone resorption which tends to help improve the eruption path of the maxillary canine
2. Opening space for the canine crown with routine orthodontic mechanics and/or maxillary expansion giving the canine more room and thus allowing for the spontaneous eruption of the impacted canine
3. However, in some situations, even these techniques do not work, and the orthodontist must refer the patient to have the impacted canine uncovered surgically
50
What are the three problems when considering an unerupted tooth that must be surgically exposed?
1. Type of surgery
2. How to attach to the impacted tooth
3. Ortho mechanics to bring the tooth into the dental arch
51
What are the three surgical techniques for uncovering an impacted maxillary canine?
1. Gingevectomy
2. Apically positioned flap (One of the cons of #2 is you are getting rid of the attached gingiva, so they are prone to periodontal problems later in life)
3. Closed eruption technique
52
Why is it critical for the orthodontist, that the oral surgeon bond to the buccal surface of the impacted canine or as close to the occlusal tip as possible?
• If the attachment is bonded in the incorrect position the
| canine will come in sideways or worse backwards
53
What are the root complications of having erupting canines or really any tooth?
* Ectopic eruption of canines (or any tooth) may cause severe root resorption of adjacent teeth
* Early screening and diagnosis are essential
* Since resorbed incisors are mostly free of pain, early detection by radiographic examination is essential to establish proper diagnosis.
* Angulation of the canine is important
* A 25 percent increase in the eruption angle of the canine relative to the lateral incisor, increases the risk of resorption of the lateral incisor by 50 percent
* Rimes and colleagues have shown that the problem often is diagnosed late, both in relation to the patient’s age and to the extent of the resorption. They suggest that dental practitioners may underestimate the problem.
54
When should you refer in regards to maxillary canine ectopic eruption?
* As soon as you see mesial movement of the maxillary canine and especially if the canine is disrupting the angulation of the maxillary lateral incisor, immediate referral and evaluation by an Orthodontist is critical. (When in doubt, send it out:)
* American Association of Orthodontists recommends that all children be evaluated by an orthodontist by the age of 8 years old
55
Treatment for older adults has been the fastest growing area in orthodontics during the last decade. True or False?
True
56
Growth modification, camouflage, and surgical options are all possible treatment options for adult orthodontics. True or False?
False. Adult treatment is more difficult due to the absence of growth, which means that growth modification to treat jaw discrepancies is not possible, which leaves only camouflage or surgical options available to the orthodontist.
57
What two steps are required for planning limited adult ortho treatment?
1. Collecting an adequate diagnostic data base
| 2. Developing a comprehensive but clearly stated list of the patient's problems.
58
What are the main goals of limited adult ortho treatment?
– Improve periodontal health by eliminating plaque harboring areas and improving the alveolar ridge contour adjacent to the teeth
– Establish favorable crown-to- root ratios and position the teeth so that occlusal forces are transmitted along the long axes of the teeth
– Facilitate restorative treatment by positioning the teeth so that:
• More ideal and conservative techniques (including implants) can be used
• Allowing optimal esthetics to be obtained through bonding, laminates, or full coverage porcelain restorations
59
An adults orthodontic records should ALWAYS include a FULL set of full mouth x-rays. True or False?
True
60
A teenagers orthodontic records should ALWAYS include a FULL set of full mouth x-rays. True or False?
False, their bone and periodontal health is usually pretty good.
61
What happens to the adjacent teeth when a first permanent molar is lost?
When a first permanent molar is lost and is not replaced, the second molar typically drifts mesially and the premolars often tip distally and rotate into the space between them
- As the teeth move the adjacent gingival tissue becomes folded and distorted, forming a plaque harboring pseudopocket that may be virtually impossible for the patient to clean
62
What are the two main orthodontic options for treating the consequences of losing a permanent first molar?
• Uprighting a tipped molar by distal crown movement leads to increased space for a bridge pontic or implant. This is a more common approach because it's easier.
• Whereas uprighting the molar by mesial root movement reduces space and might eliminate the need for a prosthesis
– but this tooth movement can be very difficult and time- consuming to accomplish
– especially if the alveolar bone has resorbed in the area where the first molar was extracted and cortical bone has filled into the extraction site
63
What is the best option for treating a lost permanent first molar with a third molar present behind it?
* For many patients distal positioning of the third molar would move it into a position in which good hygiene could not be maintained or it would not be in functional occlusion.
* In these circumstances, it is more appropriate to extract the third molar and simply upright the remaining second molar tooth.
* If both molars are to be uprighted, a significant change in technique is required and treatment time will also be significantly increased
64
What does uprighting a tipped molar do to the crown height and depth of the mesial pocket?
It increases the crown height while reducing the depth of the mesial pocket.
65
Reducing the height of the molar crown by shaving it down is a routine part of molar uprighting. True or False?
True. Crown reduction decreases occlusal interference and also improves the ratio of crown height to supported root length of the molar.
-- This will also improve the mesial pseudopocket, as well as forces along the tooth.
66
What are the eight guidelines that the dental team should follow when planning interdisciplinary treatment?
1. Realistic objectives
2. Create a diagnostic set-up
3. Determine the sequence of treatment
4. Stabilize/ correct any active disease
5. Position teeth to facilitate restorative treatment
6. Evaluate gingival esthetics
7. Take progress radiographs
8. All members interact during finishing
67
How are one wall periodontal defects best treated?
• One wall defects are the type which are treated most efficiently by the orthodontist.
– In these situations, periodontal pathogenic bacteria have destroyed the attachment on three of the four interproximal walls, leaving one wall remaining.
• One wall defects are difficult for a periodontist to manage, because resective surgery could be too destructive, and regenerative therapy is inappropriate.
• Orthodontic eruption of the tooth can eliminate these defects
68
How are two wall periodontal defects best treated?
• Two wall periodontal defects are best treated with periodontal surgery with or without adjunctive orthodontics
– When two walls are remaining in an inter-proximal region, and the patient cannot maintain the area, it is difficult for a periodontist to completely resolve the defect with resective or regenerative treatment.
– These defects often require orthodontic eruption of the affected tooth, followed by crown lengthening to improve the restorability of the tooth.
69
How are three wall periodontal defects best treated?
-- Three wall defects are not resolvable with orthodontics. These defects are generally treated with regenerative therapy, using either autogenous or alloplastic bone grafts in the affected area.
– Orthodontic treatment can begin 6 months after placement of the bone graft and the area has been shown to be stable.
70
When orthodontic brackets are placed on an adult patient, the decision as to where to place these brackets or bands is not determined by the interproximal bone level, but rather by the anatomy of the tooth. True or False?
False, it is backward. When orthodontic brackets are placed on an adult patient the decision as to where to place these brackets or bands is not determined by the anatomy of the tooth but rather by the interproximal bone level.
71
If the bone level is oriented in the same direction as the marginal ridge discrepancy, then leveling the marginal ridges will level the bone. True or False?
True.
- However, if the bone level is flat between adjacent teeth and the marginal ridges are at significantly different levels, correction of the marginal ridge discrepancy orthodontically produces a hemiseptal defect in the bone.
• This could cause a periodontal pocket between the two teeth
- Whenever possible the bone should be leveled orthodontically and any remaining discrepancies between the marginal ridges should be equilibrated.
• This method produces the best occlusal result and improves the periodontal health
• Patients should be seen every 2 – 3 months by their dentist or periodontist during the leveling process to control inflammation in the interproximal region
72
If an adult patient has considerable gingival recession and bone loss, would it be more effective to alight the crowns of the teeth orthodontically, or to align the teeth so their bone level is at the same level?
• By aligning the crowns of the teeth, the clinician may perpetuate tooth mobility by maintaining an unfavorable crown to root ratio.
– Also by aligning the crowns of the teeth and disregarding the bone level, significant bone discrepancies occur between healthy and periodontally diseased roots, which could require periodontal surgery.
• Many of these problems can be corrected by using the bone level as a guide to position the brackets on the teeth.
• In these situations, the crowns of the teeth may require considerable equilibration but:
– Bone health
– Periodontal health and
– Crown to root ratios will all be improved and the patient may not require periodontal surgery.
73
What type of lesions are the most difficult to maintain and can worsen during orthodontic therapy?
Furcation lesions
74
What are the three furcation classifications?
– Class 1 – Very shallow and do not enter the furcation deeply. These are typically just observed and monitored during orthodontic treatment
– Class 2 – Extend into the furcation but does not completely go through
– Class 3 – Lesion goes completely through the furcation.
75
If a patient has a class III furcation and is to be undergoing ortho treatment, what are the steps taken?
```
• If the patient is to be undergoing orthodontic treatment the tooth is moved first and then the tooth is hemisected after treatment is complete.
• A patient with a class 3 furcation can be treated by eliminating the furcation by hemisecting the crown and roots of the tooth.
– (works well for mandibular molars) but this procedure requires endodontic, periodontal and restorative procedures.
• This treatment is an option that should be considered in special circumstances, but implants may be a better alternative to hemisecting treatment.
```
76
What are the two ways for clinicans to address long term incisal wear with subsequent overeruption (short clinical crowns and disproportionate marginal gingiva)?
1. Crown lengthening
| 2. Orthodontic Intrusion
77
What are the advantages of performing orthodontic intrusion for short clinical worn down crowns rather than crown lengthening?
• Crown lengthening exposes cementum and subsequently requires a more invasive, full coverage restoration.
• Orthodontic intrusion provides the potential benefit of limiting the restored area to enamel and often results in a more conservative bonded veneer restoration
– Orthodontic intrusion is beneficial restoratively only if the bone level and gingival margin follows the tooth as it moves apically, which in the absence of disease is what happens.
78
Why can opening the patient's vertical cause problems for worn down teeth?
• Although some clinicians believe that patients with anterior tooth wear are “overclosed” and need to have their vertical dimension increased, this diagnosis and the resulting treatment plan are usually inappropriate.
• The problem typically is compensatory eruption of the anterior teeth, secondary to incisal wear.
• The problem for the restorative dentist is that there is insufficient space to restore these teeth without further:
– Tooth reduction,
– Crown lengthening and
– Root canal treatment
79
What are the considerations with patients that have severe attrition of the mandibular anterior teeth and insufficient crown length to either place an ortho bracket or to permit adequate ferrule for tooth preparation?
• In these situations periodontal surgery and crown lengthening prior to orthodontic intrusion may be appropriate.
• If there is not 1.5 to 2.0mm of ferrule then crown lengthening surgery should be performed first to establish adequate ferrule then the teeth should be intruded orthodontically to create the correct vertical position prior to restoration.
– This will provide access to bond orthodontic brackets to intrude the teeth.
80
How do you correctly determine a patient's correct occlusal plane?
• To do this you identify the occlusal contact point between the maxillary and mandibular second molars posteriorly and the level of the patient’s upper lip at rest anteriorly. These reference points are points that cannot be changed but that are important to stability and esthetics
81
Opening the vertical dimension by extruding maxillary and or mandibular molars is stable in adults. True or False?
False, it is not, since adults are not growing.
-– The muscles of mastication do not have the capacity to stretch in adults and attempts to increase posterior facial height with orthognathic surgery have consistently been unstable, and the vertical dimension usually reverts to its original level.
• That is not to say that there are not occasions when patients are overclosed and opening the vertical dimension is appropriate.
• But special care must be taken so that when the patients vertical is opened there is not an impingement on the patients freeway space, which is typically 2-4mm.
• If the treatment plan involves opening a patients vertical, every tooth will need to be crowned/restored, be sure to evaluate crown to root ratios.
– These patients are best treated by a prosthodontist and these cases should be referred out.
82
What is a possible treatment on teeth that have fractured the crowns that extend beneath the level of the gingival margin and terminate at the level of the alveolar ridge?
* If a patient severely fractures the crown of their tooth, the general practitioner must evaluate if the tooth can be restored or if the tooth must be extracted.
* Orthodontic forced eruption should be considered in these situations as a possible treatment, to aid in the restoration of these teeth.
* Without forced eruption, these teeth are destined for extraction or periodontal crown lengthening procedures, which often result in long unaesthetic teeth with visible restorative margins.
83
What are the different types of problems that orthodontic forced eruption can fix?
– Esthetic enhancement of the maxillary anterior periodontium
– Recontouring infrabony periodontal defects in anterior and posterior areas
– esthetic restoration of subgingival and subosseous dental fractures, carious lesions, and resorbed areas
– maintenance of osseous integrity in "early" trauma sites (for eventual implant replacements)
– slow extrusion of hopeless periodontally involved teeth in preparation for implant placement
84
What are the differences between rapid and slow forced eruption (extrusion)?
* During slow extrusion in the normal course of events, bone and gingival movements follow the eruption of the tooth under low-intensity extrusive forces.
* When stronger traction forces are exerted, as in rapid extrusion, coronal migration of the tissues supporting the tooth is less pronounced because the rapid movement exceeds their capacity for physiologic adaptation. (Like a controlled extraction of the tooth)
* Rapid extrusion is associated with a risk that the periodontal ligament will be torn and that tooth ankylosis may occur and also can place high intrusive forces on the adjacent teeth
* Slow eruption may require a periodontal crown lengthening procedure to re- contour the gingiva and bone once the orthodontic eruption is complete
85
What are the six criteria that determine whether a tooth should be forcibly erupted or extracted?
1. Root length
2. Root form
3. Level of fracture
4. Relative importance of the tooth
5. Esthetics
6. Endo/Perio prognosis
86
What are the characteristics of 1) Root length when deciding whether to forcibly erupt (extrude) or extract a tooth?
1) Root length – Root must be long enough so at least a one to one crown to root ratio will be preserved after the root has been erupted. If the fracture extends to the level of the bone the tooth must be erupted 4mm.
• The first 2.5 mm moves the fracture margin far enough away from the bone for biologic width the other 1.5 allows for the proper amount of tooth to accommodate the ferrule rule for adequate crown resistance form.
• Biologic width
– it is the height between the deepest point of the gingival sulcus and the alveolar bone crest (typically 2.5mm.)
– Invasion of biologic width for additional restorative retention will cause iatrogenic periodontal disease with a premature loss of restoration.
– When the restoration margin is placed too far below the gingival tissue crest, it will impinge on the gingival attachment apparatus and a constant inflammation is created and made worse by the patient’s inability to clean this area.
– The body attempts to recreate room between the alveolar bone and the margin to allow space for issue reattachment
87
What are the characteristics of 2) Root form when deciding whether to forcibly erupt (extrude) or extract a tooth?
– 2) Root form – root should be broad and non tapering.
– A root with significant taper could compromise esthetics of the final restoration once the tooth has been erupted 4mm.
– Internal root form is also important. If the root canal is wide, the distance between the external root surface and the root canal filling will be narrow, which may cause the walls of the crown preparation to be too thin.
– As a general rule the root canal should not be more than one third of the overall width of the root.
88
What are the characteristics of 3) level of fracture when deciding whether to forcibly erupt (extrude) or extract a tooth?
– 3) Level of fracture – If the entire crown is fractured 2 to 3 mm apical to the level of the alveolar bone, it is difficult, if not impossible, to attach to the root to erupt it.
89
What are the characteristics of 4) relative importance of the tooth when deciding whether to forcibly erupt (extrude) or extract a tooth?
– 4) Relative importance of the tooth – A 15 year old with adjacent teeth which were unrestored would be a better candidate than a 70 year old with multiple crowns and restorations.
90
What are the characteristics of 5) esthetics when deciding whether to forcibly erupt (extrude) or extract a tooth?
– 5) Esthe/cs – If the patient has a high lip line and displays 2 – 3 mm of gingiva when smiling, then any type of restoration in this area will be more obvious. In this situation, keeping the patients own tooth would be much more esthetic than any type of implant or prosthetic replacement
91
What are the characteristics of 6) endo/perio prognosis when deciding whether to forcibly erupt (extrude) or extract a tooth?
– 6) Endo/Perio prognosis – If the tooth has a significant periodontal defect, or cannot be treated endodontically, it may not be possible to retain the root.
92
What is the most important factor in successful placement of endosseous implants?
The presence of adequate alveolar bone at the recipient site
93
Orthodontic extrusion can be used to increase the vertical bone height and volume prior to implant placement. True or False?
True
-The increase in the vertical osseous dimension at interproximal sites may assist in the preservation of the interdental papillae and can further enhance gingival esthetics.
94
What are the main three disadvantages of forced orthodontic eruption?
1. Wearing an orthodontic device, as is required for orthodontic extrusion, may cause esthetic problems and may adversely affect oral hygiene
2. The duration of treatment may discourage some patients from seeking orthodontic treatment
3. At the end of the procedure, conservative periodontal surgery may be necessary to correct any discrepancy that has developed between adjacent periodontal levels.
95
What are the two major causes of relapse after ortho treatment?
1. Continued growth by the patient in an unfavorable pattern
| 2. Tissue rebound after the release of orthodontic force
96
What role do periodontal trans-septal fibers play in dental relapse after ortho treatment?
• Periodontal trans-septal fibers: extend inter-proximally over the alveolar bone and are embedded in the cementum of adjacent teeth.
They form an interdental ligament and keep all the teeth in contact. These fibers may be considered as belonging to the gingiva because they don’t have an osseous attachment
– Note:
• The trans-septal fibers (C) passing from the cementum of one tooth, over the top of the septal alveolar bone (D), to anchor into the cementum of the adjacent tooth.
97
What is the major reason for retention after ortho treatment?
To hold the teeth until soft tissue remodeling can take place.
• Even with the best tissue remodeling, however, some rebound from the application of orthodontic forces occurs.
98
What are the two ways to deal with the rebound immediately post ortho treatment?
1. Overtreatment, so that any rebound will only bring the teeth back to their proper position.
2. Adjunctive periodontal surgery to reduce rebound from elastic fibers in the gingiva
99
How much should class II or class III malocclusions be over treated by to accommodate for an expected relapse post ortho treatment?
By 1 to 2 mm
100
How much should crossbite malocclusions be over treated by to accommodate for an expected relapse post ortho treatment?
By 1 to 2 mm
101
How should irregular and rotated teeth be approached to accommodate for an expected relapse post ortho treatment?
Irregular and rotated teeth should be held in a slightly over corrected position (either by activating wings or rotation wedges) for a few months but should not be incorporated into finishing wires.
102
What is a circumferential supracrestal fibrotomy (CSF)?
– This procedure consists of inserting the sharp point of a fine blade into the gingival sulcus down to the crest of the alveolar bone.
– Cuts are made interproximally on each side of rotated tooth and along the labial and lingual gingiva margins, unless the labial or lingual margins are thin.
– No periodontal pack is necessary and there is only minor discomfort after the procedure.
• An alternative method is to make an incision in the center of each gingival papilla 1 – 2 mm below the height of the bone buccally and lingually.
– This modification is said to reduce the possibility that the height of the gingival attachment will be reduced after the surgery, and is particularly indicated for esthetically sensitive areas (maxillary incisor region)
- Neither CSF nor the papilla-dividing procedure should be done until misaligned teeth have been corrected and held in their new position for several months.
103
What does sectioning the gingival fibers help control and not help control?
- Sectioning the gingival fibers is an effective method to control rotational relapse but does not control the tendency for crowded incisors to again become irregular.
104
What is the primary indication for gingival surgery around or during ortho treatment?
The primary indication for gingival surgery therefore is a tooth or teeth that were severely rotated. This surgery is not indicated for patients with crowding without rotations.
105
How does the frenum affect ortho treatment?
* The frena may jeopardize the gingival health when they are attached too closely to the gingival margin, either due to an interference in the plaque control or due to a muscle pull
* In addition to this, the maxillary frenum may present aesthetic problems or compromise the orthodontic result causing a recurrence after the treatment.
106
When is the frenum indicated for removal with ortho treatment? What three scenarios?
1. An frenal attachment is present, which causes a midline diastema
2. A flattened interdental papilla with the frenum closely attached to the gingival margin, which causes a gingival recession and a hindrance in maintaining the oral hygiene.
3. An frenum with an inadequately attached gingiva and a shallow vestibule is seen.
107
What are the things we CAN control in orthodontics?
1. Diagnosis
2. Treatmentplan
3. Selection of orthodontic
appliances
4. Brackets, wires, bands
5. Placement of orthodontic
appliances
6. Forces on teeth
108
What are the things we CANNOT control in orthodontics?
```
• Patient compliance
• Oral Hygiene
• Elastics
• Appointments
• Growth
• Tooth size and form
• Root resorption
• Ankylosis
• Impacted teeth
• Abnormal tooth eruption
• Bone loss, gingival recession,
periodontal disease
• Temporal mandibular joint disorders
• Muscle/Oral habits- tongue, thumb
• Post treatment tooth movement
```
109
What are the items covered and assessed at the initial consultation?
Questionnaire/Consultation Chief concern
Medical history Dental history Habits
Clinical Evaluation
Oral Health – dental and periodontal, caries, recession, bone loss
TMJ evaluation – max opening, lateral range, CR/CO
Facial and dental Appearance Pathology
Radiographic examination (panoramic) Missing, supernumerary, impacted
Molar and canine relationship Transverse and Anterior Posterior relationships (AP), dentally and skeletally
– Crowding, Spacing
– Overjet , Overbite, Curve of
Spee, Curve of Wilson
– Midlines
– Profile
– Chin deviation
– Developmental age compared to dental age
– Growth Disharmony
– Lip position
– Primary teeth eruption
– Tooth size, shape
110
What can be injected directly into the PDL to increase the rate of tooth movement?
Prostaglandin, but this is quite painful. That's essentially what a beesting is.
111
What are the two types of drugs that are known to depress the response of orthodontic force?
1. Prostaglandin inhibitors - pain control
| 2. Bisphosphonates - used in the treatment of osteoporosis
112
How do bisphosphonates act?
* Bisphosphonates bind to hydroxyapatite in bone and act as specific inhibitors of osteoclast-mediated bone resorption.
* These drugs are incorporated into the structure of the bone then slowly eliminated over a period of years, so stopping the drug does not eliminate all of its effects
* Most of the drug is absorbed on the surface of the bone, which makes orthodontic treatment possible after about 3 months with no further bisphosphonate therapy
113
Where are prostaglandins derived from?
Formed from arachidonic acid, which in turn is derived from phospholipids
114
What do corticosteroids do?
Reduce prostaglandin synthesis by inhibiting the formation of arachidonic acid to prostaglandins
115
All NSAIDS affect orthodontic force movement. True or False?
False. The more potent members of this group that are used in the treatment of arthritis like indomethacin do, but over the counter NSAIDs are short acting and do not affect ortho treatment if used to control pain. But if an adult or child is being treated for arthritis and is chronically taking the medication, then it can be a problem.
116
What other types of drugs can affect prostaglandin levels and affect the response to ortho force?
* Tri-cyclic antidepressants – Doxepin, Imipramine
* Antiarrhythmic agents - Procaine
* Anti-malarial drugs - Quinine
* Anticonvulsant - Phenytoin
117
How are orthodontic casts trimmed?
The backs are trimmed perpendicular to the midsagittal line. This allows them to be picked up in maximum intercuspation.
118
For orthodontic casts, precise angulation is more important than symmetry. True or False?
False, symmetry is more important. The angles shown for the casts are suggested values.
119
What items are measured once the orthodontic cast models are made?
1. Occlusal and canine relationships
2. Tooth size, shape and morphology (If teeth in either arch are larger or smaller the occlusal relationship won’t align correctly, and the orthodontist must allow for this in the final treatment plan)
3. Overjet, overbite, and open bite (Millimeter measurements describing the severity of each individual problem.)
120
Crowding is worse when the incisors are flared. True or False?
False, they are worse when they are positioned lingually, less space, smaller arch circle.
121
How is space analysis with teeth usually done?
The analysis can be done either directly on the dental casts or by a computer algorithm after appropriate digitization of the arch and tooth dimensions by scanning the casts, or intra-orally.
• Available space minus space required is used to determine the amount of crowding or spacing.
122
What is the first step of space analysis of teeth?
The first step is calculation of the space available
– This is accomplished by measuring arch perimeter from the mesial of one first molar to the mesial of the other over the buccal cusps and incisal edges.
• This can be done by dividing the dental arch into segments that can be measured as straight line approximations of the arch
– Another method can be used by contouring a piece of wire or curved line on a computer image to the arch.
• then measuring the length of wire or have the computer compute the length of the line.
123
What is the second step of space analysis of teeth?
• The Second step is to calculate the amount of space required
– This is done by measuring the mesiodistal width of each erupted tooth from contact point to contact point and estimating the widths of the size of the unerupted teeth
124
What are the three assumptions that must be made in order for space analysis to be correct?
1. The anterio-posterior position of the incisors is correct
2. The space available will not change because of growth and dental compensatory tipping
3. All the teeth are present and are reasonably normal in size
• None of these assumptions can be taken for granted and all of them must be kept in mind when space analysis is performed.
– This is one of the many reasons why Orthodontics is so difficult.
– Treatment plans must be thoroughly thought through, analyzed, and adjusted if necessary through out treatment.
125
The assumption that space available will not change during growth, is valid for most but not all children. True or False?
True
– In a child with a well-proportioned face, there is little or no tendency for the dentition to be displaced relative to the jaw during growth
– Teeth will often shift anteriorly or posteriorly in a child with a jaw discrepancy, for this reason space analysis is less accurate and less useful for children with skeletal problems.
126
How do you estimate space required in the mixed dentition in the mandibular arch using the Tanaka and Johnston prediction values?
- First, you measure the four incisors from distal to mesial, even if they are rotated, and then lets say you get 22.5mm.
- Then you take half of that and get 11.25 mm
- Then you use pre-fabricated numbers, +10.5 = width of the mandibular canine and premolars in one quadrant. And +11mm = width of the maxillary canine and premolars in one quadrant.
- So we would have 11.25mm + 10.5mm = 21.75mm on the mandibular right quadrant and mandibular left quadrant separately.
- Now we add 22.5mm + 21.75mm + 21.75mm = 66mm, which is the total estimated space required in the mixed dentition in the mandibular arch.
127
What is the Bolton Analysis?
• The Bolton analysis has been designed following observation that tooth size was important to ideal occlusion.
• In order to obtain the proper interdigitation and arch coordination when the molars are in a Class I relationship, the dimension of the lower teeth has to be proportional to the dimension of the upper teeth.
• For a patient to have a normal overbite and overjet, the lower teeth must occupy a dental arch that is smaller than the upper arch.
• Bolton calculated that a constant proportion between the upper and the lower dentition was present when the occlusion was perfect.
• He determined that the sum of the mesio-distal dimension of the lower teeth must be equal to 91% of the sum of the mesio-distal dimension of the upper teeth.
• He also discovered that a satisfactory Class I canine occlusion was only possible if a specific proportion was present between the upper and lower anterior teeth.
• The sum of the size of the mesio-distal dimension of the lower anteriors (canine to canine) must be 77% of the sum of the size of the mesio-distal dimension of the upper anterior teeth(canine to canine).
– The Bolton analysis is now mainly used for the anterior region (canine to canine).
128
According to the bolton analysis, what percentage should the sum of the mandibular mesio-distal dimensions make up of the maxillary sum?
91%
129
According to the bolton analysis, what percentage should the sum of the maxillary mesio-distal dimensions of canine to canine make up of the maxillary sum?
77%
130
When looking at a photograph of the face from the front and from the side, what are the thirds that the image can be split into?
• In modern Caucasians, the lower facial third often is slightly longer than the central third.
• The lower third has thirds:
1) The corners of the mouth
should be 1/3 of the way between the base of the nose and the chin.
2) The chin and lower lip should occupy 2/3 of the lower third.
131
What are the vertical lines that the face can be split into when looking at it straight on?
– An ideally proportional face can be divided into central, medial, and lateral equal fifths.
– The separation of the eyes and the width of the eyes, which should be equal, determine the central and medial fifths.
– The lateral fifths are from the outside corner of the eye to the edge of the face.
– The nose and chin should be centered within the central fifth,
• With the width of the nose the same as or slightly wider than the central fifth.
– The inter-pupillary distance (dotted line) should equal the width of the mouth.
132
When is facial asymmetry considered abnormal?
When it is noticeable to the general public or patient
133
Usually the left side of the face is a little larger than the right. True or False?
False, the right side is usually a little larger.
134
Profile convexity or concavity results from a disproportion in the size of the jaws and can indicate which jaw is at fault. True or False?
False. Profile convexity or concavity
| results from a disproportion in the size of the jaws but does not by itself indicate which jaw is at fault.
135
A convex facial profile indicated a class II jaw relationship. True or False?
True. Which can result from either a maxilla that projects too far forward or a mandible too far back.
136
A concave profile indicated a class III jaw relationship. True or False?
True. Which can result from either a maxilla that is too far back or a mandible that protrudes forward.
137
What are the three ways in which bimaxillary dentoalveolar protrusion is seen in the facial appearance?
Bimaxillary dentoalveolar protrusion is seen in the facial appearance in three ways:
1. Excessive separation of the lips at rest (lip incompetence).
• The general guideline (which holds for all racial groups) is that lip separation at rest should be not more than 4 mm.
2. Excessive effort to bring the lips into closure (lip strain and mentalis activity( chin dimpling)).
3. Prominence of lips in the profile view.
138
A general guideline is that lip separation at rest should not be more than 3 mm. True or False?
False, 4 mm is the answer.
139
All three soft tissue characteristics must be present to make the diagnosis of bimaxillary dentoalveolar dental protrusion. True or False?
True
140
Different racial groups and individuals within those groups have different degrees of lip prominence that are independent of tooth position. True or False?
True
141
Excessive dental protrusion is a diagnosis that can be made accurately from cephalometric radiographs. True or False?
False, excessive dental protrusion must be a clinical diagnosis. It cannot be made accurately from cephalometric radiographs.
142
What is the usual cause of excessive display of maxillary gingiva?
The usual cause of excessive display of maxillary gingiva is a long face due to excessive downward growth of the maxilla, which moves the maxilla down below the upper lip and results in a disproportionately long lower third of the face.
143
What are the other two things that can cause gingival display in excess?
1. Incomplete eruption of the teeth
| 2. A short upper lip (botox injections, surgery)
144
Growth of the upper lip as the patient ages typically reduces some excessive gingival display. True or False?
True
145
As a person ages, more gingiva and maxillary incisor show is normal. True or False?
False. As a person ages, less gingiva and maxillary incisor show is normal.
– This happens as the upper lip lengthens with age and the teeth wear down from use.
– Having less maxillary incisal show gives the face an older appearance.
146
What two things can contribute to a stepped throat contour?
Both submental fat deposition and a low tongue posture contribute to a stepped throat contour, which becomes a “double chin” when extreme.
147
In what terms is throat form evaluated?
The throat form is evaluated in terms of the contour of the submental tissues.
148
What is the ideal chin-throat angle?
Closer to 90 degrees is better
149
When the mandible is deficient or short, throat length is usually long. True or False?
False, throat length is usually short.
150
When someone has more submental fat, the chin-throat angle is somewhat more obtuse usually. True or False?
True
151
The width of the maxillary dental arch, as seen on smile, should be proportional to the width of the midface. True or False?
True
152
What is the smile arc?
The smile arc is the relationship of the curvature of the lower lip to the curvature of the maxillary incisors.
153
In terms of the golden proportion, what are the percentage widths of the lateral from the central, canine, from the lateral, etc., when looking straight on?
It can be seen that the width of the lateral incisor is 62% of the width of the central incisor; the (apparent) width of the canine is 62% of the width of the lateral incisor; and the (apparent) width of the first premolar is 62% of the width of the canine.
154
For the central incisor, at what percentage should the width of the tooth be at of its height?
About 80%. Or the length should be 20% longer than the width.
-This patient’s central incisors look almost square, because their width is normal but their length is not.
155
What is the zenith?
The height of contour of the gingiva over a tooth.
156
Where should the zenith be located from the midline on a maxillary central incisor?
Distal to the midline. And for ideal appearance, the contour of the gingiva over the maxillary central incisors is a horizontal half- ellipse (i.e., flattened horizontally)
157
What is the gingival contour of a maxillary lateral incisor and where is the zenith located from the midline?
The maxillary lateral incisor, in contrast, has a gingival contour of a half-circle, with the zenith at the midline of the tooth.
158
What is the gingival contour of the canine and where is the zenith located from the midline?
The canine gingival contour is a vertical half-ellipse (i.e., higher contour than a half circle), with the zenith just distal to the mid-line.
159
At what height should the gingival height be when comparing the maxillary central, lateral, and canine?
The gingival height should be the same for the central incisors and canines with the lateral incisors being 0.5 – 1.0mm below a line connecting the canine gingival height and the central gingival height
160
In which direction to the contact points of maxillary teeth move from the central incisors to the premolars?
The contact points of the maxillary teeth move progressively gingivally from the central incisors to the premolars, so that there is a progressively larger incisal embrasure.
161
The embrasure angle also gets progressively smaller going form the central incisors posteriorly. True or False?
False, they get larger
162
What is the "connector" when talking about contact points? And does it increase or decrease is it goes from the centrals posteriorly?
The connector is the area that looks to be in contact in an unmagnified frontal view.
– Note that the connector decreases in size from the centrals posteriorly.
– Connectors that are too short often are part of the problem when “black triangles” appear between the teeth because the gingival embrasures are not filled with gingival papillae
163
What is natural head position when referring to radiographs?
• The cephalometric radiograph is taken with the patient in natural head position (NHP),
– Natural head position is having the patient stand in a relaxed natural position when the x-ray is taken staring at a point directly in front of them.
– NHP is preferred in modern cephalometrics to anatomic head positioning (Positioning the head for the patient)
164
What is the panoramic x-ray used to evaluate?
```
– Missing teeth,
– Extra or abnormal teeth
– Abnormal eruption patterns
– Evaluate the TMJ
– Bone level
– Root structure, (length/resorption)
– Pathology
```
165
What is the major goal of cephalometric analysis?
To establish the relationship of the cranium and cranial base, maxilla and naxomaxillary complex, mandible, maxillary and mandibular teeth and their alveolar processes in both the anterior-posterior and vertical planes of space.
166
What can cause class II division I malocclusion?
Produced by protrusion of the maxillary teeth although the jaw relationship was normal
167
What are five things that excessive vertical growth of the maxilla can do to the mandible and the rest of the smile?
1. Cause the mandible to perform a downward-backward rotation
2. Anterior open bite
3. High mandibular plane angle
4. Over-eruption of mandibular incisors
5. Gummy smile
168
What are the three major superimpositions used in orthodontics?
1. Superimposition on the anterior cranial base along the SN line
2. Superimposition on the maxilla, specifically on the contour of the palate behind the incisors and long the palatal plane
3. Superimposition on the mandible, specifically on the inner surface of the mandibular symphysis and the outline of the mandibular canal and unerupted third molar crypts
169
What are the characteristics of the superimposition on the anterior cranial base along the SN line?
* This superimposition shows the overall pattern of changes in the face, which result from a combination of growth and treatment in children receiving orthodontic therapy.
* Note: in this patient that the lower jaw grew downward and forward, while the upper jaw moved straight down. This allowed the correction of the patient’s Class II malocclusion.
170
What are the characteristics of superimposition on the maxilla, specifically on the contour of the palate behind the incisors and along the palatal plane?
* This view shows changes of the maxillary teeth relative to the maxilla.
* Note: in this patient’s case, minimal changes occurred, the most notable being a forward movement of the upper first molar when the second primary molar was lost.
171
What are the characteristics of superimposition on the mandible, specifically on the inner surface of the mandibular symphysis and the outline of the mandibular canal and unerupted third molar crypts?
* This superimposition shows both changes in the mandibular ramus and condylar process (due to growth or treatment) and changes in the position of the mandibular teeth relative to the mandible.
* Note: that the mandibular ramus increased in length posteriorly, while the condyle grew upward and backward. As would be expected, the mandibular molar teeth moved forward as the transition from the mixed to the early permanent dentition occurred.
172
What problems need to be addressed first in treatment planning?
Pathologic problems must be brought under control before orthodontic treatment begins.
173
Patients must be evaluated for abnormalities in skeletal, dental, and soft tissue elements, in all three planes of space. True or False?
True
174
What are three common anatomic landmarks that need to be bisected because they are bilateral structures?
1. Porion
2. Orbitale
3. Gonion
175
When referring to cephalometric anatomic landmarks, what is (S)?
S = Sella (S) -- Center of the pituitary fossa of the sphenoid bone.
176
When referring to cephalometric anatomic landmarks, what is (N)?
N = Nasion (N) – Intersection of the internasal suture with the nasofrontal suture in the midsagittal plane
177
When referring to cephalometric anatomic landmarks, what is (Or)?
Or = Orbitale (Or) – Lowest point of the floor of the orbit, the most inferior point of the external border of the orbital cavity (bisected)
178
When referring to cephalometric anatomic landmarks, what is (Po)?
Po = Porion (Po) – The point on the upper most portion of the external auditory meatus (bisected)
179
When referring to cephalometric anatomic landmarks, what is (ANS)?
ANS = Anterior nasal spine (ANS) – Most anterior bony point on the maxilla at the base of the nose
180
When referring to cephalometric anatomic landmarks, what is (PNS)?
PNS = Posterior nasal spine (PNS) – Posterior limit of the bony palate
181
When referring to cephalometric anatomic landmarks, what is the A point?
A Point = A point – Deepest point of the curve of the maxilla, between anterior nasal spine and the dental alveolus. Usually located just opposite the root tip of the central incisor
182
When referring to cephalometric anatomic landmarks, what is the B point?
B Point = B point – Most posterior point in the concavity along the anterior border of the symphysis, usually opposite the root tip of the mandibular incisor. Represents the anterior limit of the mandibular base.
183
When referring to cephalometric anatomic landmarks, what is (Pog)?
Pog = Pogonion (Pog) – The most anterior point on the anterior curvature of the mandibular symphysis
184
When referring to cephalometric anatomic landmarks, what is (Gn)?
Gn = Gnathion (Gn)—the most outward and everted point on the profile curvature of the symphysis of the mandible, located midway between pogonion and menton.
185
When referring to cephalometric anatomic landmarks, what is (Me)?
Me = Menton (Me) – Most inferior point on the mandibular symphysis
186
When referring to cephalometric anatomic landmarks, what is (Go)?
Go = Gonion (Go) – The point at the middle of the curvature at the angle of the mandible. Represents the junction of the ramus and the body of the mandible at its posterior inferior aspect, (bisected)
187
When referring to cephalometric planes, what is (SN)?
Sella – Nasion (SN) – Plane formed by connecting S point to N Point
188
When referring to cephalometric planes, what is (FH)?
Frankfort Horizontal (FH) – Formed by connecting porion and orbitale.
189
When referring to cephalometric planes, what is (PP)?
Palatal Plane (PP) – Formed by a line connecting anterior nasal spine to posterior nasal spine
190
When referring to cephalometric planes, what is (OP)?
Occlusal Plane (OP) – Formed by a line connecting the distal cusp of the mandibular first molar and the incisal edge of the mandibular incisors.
191
When referring to cephalometric planes, what is (MP)?
Mandibular plane (MP) – A line is drawn from menton to gonion.
192
When referring to cephalometric planes, what is (S-Gn)?
Y – Axis (S-Gn) – The line connecting sella to gnathion. This line us used as an indicator for vertical facial growth tendency
193
What should the number be for SN-A, and what does the angle indicate?
Reference Line: Sella - Nasion
This angle indicates the horizontal position of the maxilla relative to the cranial base.
>85° - protrusive or prognathic maxilla
194
What should the number be for SN-B, and what does the angle indicate?
Reference Line: Sella - Nasion
B-point is the most anterior measure point of the mandibular apical base. This angle expresses the horizontal position of the mandible relative to the cranial base using B-point as a cephalometric landmark.
>82° - prognathic mandible
195
If a single primary molar has been lost bilaterally and the permanent incisors haven't erupted, what is the space maintainer of choice?
A pair of band and loop space maintainers, because a lingual arch would interfere with the eruption of the permanent incisors often erupt lingually. Otherwise, a lingual arch is better.
196
If a primary second molar is lost before eruption of the permanent first molar, what type of space maintainer would be best?
The distal shoe, which would be placed at or very soon after the extraction of the primary molar.
197
A lingual arch should never be used on maxillary teeth. True or False?
False, you can as long as the overbite is not excessive.
198
If the overbite is excessive and you don't want to use a lingual arch on the palate for space maintenance of maxillary teeth, what should you use?
A nance arch with an acrylic button in the palatal vault.
199
What does the transpalatal arch do?
It preventts a molar from rotating mesially into a primary molar extraction space, and prevents mesial migration.
200
When can a spur on a lingual arch be used?
In mixed dentition to either maintain a correct midline when a primary canine is lost or to retain a corrected midline.
201
What can vertical ortho tooth repositioning help with in adult ortho treatment?
Can improve certain types of osseous defects in periodontal patients, which can eliminate the need for resective osseous surgery.
202
For adult ortho treatment, articulator-mounted casts are usually not needed. True or False?
False, they facilitate the planning of associated restorative procedures.
203
How often should adult ortho patients be seen and on what type of schedule should they be put on?
On a 2-3 month periodontal recall schedule during the leveling process to control inflammation in the interproximal region.
204
When should a frenectomy due to a midline diastema be performed?
After the diastema has been closed orthodontically so healing can be done with the teeth in their proper position.
205
What should the number be for ANB, and what does the angle indicate?
The ANB angle measures the relative position of the maxilla to mandible. The ANB angle can be measured or calculated from the formula: ANB = SNA - SNB.
1. A positive ANB angle indicates that the maxilla is positioned anteriorly
relatively to the mandible (Class I or Class II malocclusion cases).
2. A negative ANB angle indicates that the maxilla is positioned posteriorly
relative to the mandible (Class III malocclusion cases).
The normal range is 1°-5°.
>5° indicates a Class II skeletal jaw relationship, protrusive maxilla or
retrognathic mandible.fdfdfdsadf
