First Semester Flashcards
What is was the problem they were trying to address in the ABO objective grading system article (1998)?
They were trying to address a way to make all phase 3 examination more objective with the grading system. Also tried establishing validity and reliability within the indexes used for grading.
Furthermore, diplomates may use this scoring system at anytime in their career to determine if they are producing “board quality” results for self-evaluation.
This would help with repeatability, accuracy, and standardized evaluation of candidates
What was known prior to the 1994 ABO committee? Were the indices that had been used valid? were they reliable?
Prior to the 1994 ABO committee several indices existed aiming to evaluate the outcome of orthodontic treatment. The PAR (peer assessment rating) index is reliable and valid, however it is not precise enough to discriminate between the minor inadequacies of tooth position that are found in ABO case reports.
The occlusal index has been used to determine treatment quality, but this method is tedious and is more appropriate for pre-treatment records rather than post-treatment
How did the ABO conduct their first study (1995) and what was the level of evidence (RCT, prospective, restrospective, etc?)
100 cases were evaluated, series of 15 criteria measured on final dental casts and pano
LOE = retrospective without controls, no selection criteria
Results = 85% of the inadequacies occurred in 7 of the 15 criteria (alignment, marginal ridges, BL inclination, OJ, occlusal relationships, occlusal contacts, root angulation)
In the ABO 1995 study, 85% of the inadequacies occurred in 7 of the 15 criteria. What were the 7?
Alignment marginal ridges BL inclination OJ Occlusal relationship Occlusal contacts Root angulation
How did the ABO conduct their second study (1996)? What did they find?
300 cases were evaluated by a subcommittee of four directors. This test was intended to verify the results of the previous test to determine if multiple examiners could score the records reliably and consistently. Again, the majority of inadequacies occurred in the same 7 categories. But the committee had difficulty establishing adequate inter examiner reliability. Thus, they suggested creating a measuring instrument to make the process more reliable.
What was different in ABO’s third study conducted in 1997? What did they find?
third field test was performed with a modified scoring system and the addition of an instrument to measure the various criteria more accurately. 832 cases were analyzed by all the directors. This time, a calibration session preceded the examination to establish increased reliability of the directors. Again, the results showed that the overwhelming majority of inadequacies occurred in the same 7 categories. however, this time, they added inter proximal contacts to the scoring system
Describe the 1998 ABO study
all directors participated in the evaluation process. the new and improved measuring instrument was used, extensive calibration of directors was performe.d. this study reaffirmed the benefits of using an objective grading system for grading the dental casts and pano, and also established standards for successful completion of this portion of the phase 3 examination. 8 criteria: alignment, marginal ridges, BL inclination, occlusal relationship, occlusal contacts, overjet, inter proximal contacts, root angulation
How does the ABO assess ideal alignment of maxillary anterior teeth?
incisal edges and lingual surface of maxillary anterior teeth (functioning surfaces and they effect esthetics)
how does the ABO assess ideal alignment of mandibular anterior teeth?
incisal edges and labial incisal surfaces
How does the ABO assess ideal alignment for maxillary posterior teeth?
MD central groove of the premolars and molars
How does the ABO assess ideal alignment for mandibular posterior teeth?
Buccal cusps of the premolars and molars
How do we achieve ideal alignment with bracket placement?
Incisal/gingival alignment determined by incisal/gingival position of brackets. BL alignment determined by the bracket prescription (and ensuring bracket is fully seated against the teeth). M/D tip determined by angling the bracket slot.
Why should the marginal ridges be at the same level according to ABO?
if marginal ridges are at the same relative height, the CEJ will be at the same lee. In a periodontally healthy individual, this will result in flat bone levels between adjacent teeth. Additionally, if marginal ridges are at the same height, it will be easier to establish proper occlusal contacts.
How are marginal ridges positioned at the same level by bracket placement?
The slot should be parallel with the plane extending from the mesial to distal marginal ridges
Describe the vertical placement of brackets following Alexander’s protocol.
Upper: central = X Lateral = X -0.5 Canine = X + 0.5 Bicuspids = X First molar = X -0.5 Second molar = X - 1
Lower: incisors = X -0.5 Canine = X +0.5 Bicuspids = X First molar = X -0.5 Second molar = X - 1
In regards to BL inclination, there should not be a significant difference between the heights of the buccal and lingual cusps of the molars and premolars. why? (per ABO)
In order to establish proper occlusion in maximum intercuspation and avoiding balancing interferences, there should not be a significant difference between the heights of the B and L cusps of the maxillary and mandibular molars and premolars.
How do the brackets help achieve correct BL inclination?
third order compensations (torque) prescribed into brackets(slots).
What are the four main factors to consider in placement of brackets in regards to BL inclination (torque)?
1) prescriptions in different appliances vary considerably.
2) Brackets must be placed occluso-gingivally at the correct height of contour given the chosen torque prescription
3) consider the expected “play” between the wire and slot
4) consider the resistance to unwanted tooth movements (EG resistance to negative torque of lower incisors in non extraction cases)
In regards to root angulation, there should be sufficient bone present between adjacent roots. Why?
if roots are properly angulated, then sufficient bone will be present between the adjacent roots, which could be important if the patient were susceptible to perio bone loss at some point in time.
how do brackets influence root angulation?
the guiding line in the bracket should be in line with the long axis of the tooth in order to achieve the proper MD root position prescribed in the bracket. Also, visualize the angulation of the bracket slot
How do we get to a well-finished case as efficiently as possible (minimal wire-bending)?
proper initial bracket placement
Prior to Andrew’s straight wire appliance, bends needed to be placed for 1st, 2nd, and 3rd order movements. Describe the first order dimension.
B/L. B/L bends placed in arch wires necessary to compensate for variation in the contour /thickness of labial surfaces of individual teeth. With a contemporary appliance, the compensation is built into the base of the bracket itself, by varying the thickness of the base depending on which tooth it is attached to. This reduces the need of first order bends.
Prior to Andrew’s straight wire appliance, bends needed to be placed for 1st, 2nd, and 3rd order movements. Describe the second order dimension.
Incisal/gingival (vertical plane). Originally, M/D root tipping required angled bends called second order bends. (step up and step down also second order because its incisal/gingivla bend). Now, prescription of the angle of the bracket slot decreases the need for these angled bends.correct bracket placement is necessary to avoid step-up and step-down bends.
Prior to Andrew’s straight wire appliance, bends needed to be placed for 1st, 2nd, and 3rd order movements. Describe the third order dimension.
B/L (root torque)
Originally, it was necessary to place a twist/torque in rectangular wires to move/control roots buccally or lingually. Now, prescription brackets are inclined to compensate for the inclination of the facial surface so the third-order bends are less necessary.
In Andrew’s article (1972) about the six keys to normal occlusion, what was the problem he was trying to address? What was known prior to his study?
improper cusp-embrasure relationship existed even after ortho treatment. he was trying to identify “ideal” parameters to orthodontically treat patients. prior to his study, Angle’s classes of malocclusion were the gold standard
In Andrew’s first study (1960-4), what was the study design and what was the level of evidence?
LOE = retrospective observational w/o controls
120 non orthodontic normal models were acquired and the crowns were examined to ascertain characteristics of ideal occlusion. inclusion criteria = never had ortho tx, straight and pleasing in appearance, bite looked generally good, Andrew’s judgment would not benefit from ortho tx.
In Andrew’s first study, how did he study and what did he find?
he gathered data because there was no standardization for what was confirmed successful orthodontic treatment (it was very subjective). Recognizing conditions in treated cases that were less than ideal was simple, but wasn’t enough. We needed criteria found through a deliberate approach to determine what was naturally ideal where its required no ortho tx and to use that for ortho tx goals.
What was different in Andrew’s second study (1965-71)?
Much greater population sample size (1,150 cases) and cases were treated by orthodontists following criteria for ideal occlusion.
This was used to learn to what degree the 6 keys were present and whether the absence of any one permitted prediction of other error factors.
Why did Andrews think his results from his second study (1965-71) were valid?
the six keys were present in each of the 120 normals, but also even the LACK of even one of the six was predictive of an incomplete end result in treated model.
What did Andrews find about molar relationship and how did it influence his bracket preadjustment?
- distal surface of the DB cusp of the U6s made contact and occluded with mesial surface of MB cusp of L7s.
- MB cusp of U6 fell within buccal groove of L6s
- only person to pre-tip the bracket to gain MD tipping of the U6s (5 degrees on first molar, none on second)
What did Andrews find about crown angulation and how did it influence his bracket preadjustment?
gingival portion of crown should be distal to the incisal portion, varying with individual tooth height. This is the reason why Andrews prescription has a positive tip on all teeth (highest for upper 3s)
What did Andrews find about crown torque for the incisors?
anterior inclination of uppers - only upper incisors exhibit positive torque in Andrews prescription
What did Andrews find about crown torque for the upper posteriors?
lingual inclination similar in degree from canines to second molars. Andrews Rx - similar negative torque for upper canines-molars
What did Andrews find about crown torque for lower posteriors?
lingual inclination increasing from canine to second molars. Andrews Rx - increasingly negative torque from lower canines to molars
According to Andrews, there should be [no/some] rotations in the teeth.
no
rotated molar takes up more MD space
How do you know if you have the correct band when placing on a tooth?
the hook is attached to the Mesial-gingval portion of the bracket (end of hook points distally)
What are some considerations when adjusting the vertical position of bands?
when viewed from buccal, the tube and band should be parallel with the buccal cusps
when viewed from occlusal, the upper molar tube should straddle the buccal groove. The lower molar tube should also straddle the buccal groove.
What are some considerations when adjusting the MD position of the bracket attached to the band?
mesial border of the buccal tube should bisect the MB cusp as seen from the occlusal view
What is the best technique to find the right size of band?
start with band that is too big, then work down to the smallest size that meets positioning criteria. (if you can position it with only finger pressure, it is still too large!)
In regards to bonded bracket placement, how do you achieve ideal alignment (rotation)?
if the tooth is not rotated, place the bracket in the center of the tooth MD to prevent rotation
On a rotated tooth, bond the bracket slightly towards the end (M/D) of the tooth that needs to be rotated out to aid in correction of the rotation.
In regards to bonded bracket placement, how do you achieve ideal vertical tooth relations and marginal ridges?
can use a measuring device or visually eyeball the vertical placement to the center of the tooth
Important to consider adjacent and contralateral teeth
pay attention to gingival height (fractured/worn teeth can throw you off)
maxillary laterals should be slightly shorter than centrals
don’t seat molar bands too far gingival
In regards to bonded bracket placement, how do you achieve ideal angulation of the crowns/roots?
use a mirror to visualize long axis of crown from facial and occlusal view
use the most prominent portion of the buccal surface as a guide
pano will help visualize long axis to see root angulation
What are the two different types of ceramic brackets?
monocrystalline
polycrystalline
What are the differences between mono crystalline and polycrystalline ceramic brackets?
Mono- offers greater strength (until bracket surface is scratched), scratches/cracks tend to spread and reduces fracture resistance to below the level of poly crystalline (scratches are likely to occur during treatment)
Poly - relatively rougher surfaces (not good for sliding and could cause more enamel damage), some of these brackets have an integrated metal slot
What’re are the two most common ways that fractures occur in ceramic brackets?
loss of part of the brackets (tie wings) during arch wire changes or eating
cracking of bracket when torque forces are applied
What are some ways that ceramic brackets compensate for their tendency to fracture?
bulkier brackets than steel
design is much closer to a wide single bracket than is usual in steel brackets
Define fracture toughness
ability to resist fracture
True or false.. the fracture toughness of ceramic brackets is greater than steel
false, it is much lower than steel.
fractures occur easier in ceramic, especially when scratched
What are some problems associated with ceramic brackets? (name 4)
fractures of brackets
resistance to sliding (some use metal slot to decrease friction)
enamel wear (risk is avoided if ceramic is only placed on upper anterior teeth)
Enamel damage from bracket removal
How can enamel damage from removal of ceramic brackets be minimized?
use debonding pliers from the manufacturers of the ceramic bracket (some brackets manufactured to break in a way to avoid enamel damage)
use thermal or laser instrument to weaken the adhesive by heating it (to induce failure whin bonding agent itself (reduces risk of enamel damage but increases risk of pulpal damage)
Ceramic brackets can be bonded chemically and/or mechanically. ceramic brackets are composed of aluminum oxide which is inert, so ____ is used to promote chemical retention
silane (coupling agent)
What are the ceramic bracket debonding techniques recommended for Clarity from 3M unitek?
Utilize the Unitek SL bracket debonding instrument preferably while brackets remain on AW
brackets are retained with mechanical retention, not chemical
concentrate stress on base side of slot so when you squeeze wings together, it creates a peeling force
What are the ceramic bracket debonding recommendations for Inspire ICE from Ormco?
Brackets utilize a ball-base design. Utilize their bracket removal plier to ensure the brackets come off easily and consistently
What are the ceramic bracket debonding recommendations for InVu from TP orthodontics?
No special instrument required, brackets use a molded polymer mesh base
step 1: after removing any flash, squeeze MD edges of mesh base with a SHARP 2-jawed instrument
step 2: the base will flex and release from the tooth, retaining most of the adhesive. the bracket should remain intact with no breaking or shattering
What are the ceramic bracket removal recommendations for the In-ovation C brackets from GAC?
place ligature cutter incisally and gingival and use to remove bracket
be careful not to cut the enamel
claims base design of bracket allows for easy debonding
What are the ceramic bracket removal recommendations for Fascination 2 brackets from Dentaurum USA?
use Weingard pliers for debonding
place a blue separating ring around bracket base for protection
These brackets use chemical bonding!
According to research (Cochrane NJ 2017), enamel damage is more frequent and severe when debonding __ brackets vs. ___ brackets
ceramic
metal
According to research (Cochrane NJ 2017), enamel damage is less severe when ceramic brackets are bonded with ___ compared to ___
RMGI cement
composite resin
According to research (Cochrane NJ 2017), where is the most common site of failure when debonding mechanically retained ceramic brackets?
bracket/bonding-material interface
According to research (Cochrane NJ 2017), which tooth has the highest risk of enamel damage when debonding ceramic brackets?
maxillary laterals
According to the Kitahara-Ceia FMA 2008 article, in a chemically retained ceramic bracket, the difference between the enamel surfaces before and after debonding [was/was not] statistically significant indicating that….
was statistically significant
procedures of bonding and debonding of chemically retained ceramic brackets resulted in enamel damage
According to the Kitahara-Ceia FMA 2008 article, in a mechanically retained ceramic bracket, the difference between the enamel surfaces before and after debonding [was/was not] statistically significant indicating that….
was not statistically significant
Mechanically bonded ceramic brackets does not significantly alter the enamel surface when debonding
According to the Suliman SN 2015 article, both polycrystalline and mono crystalline ceramic brackets can be debonded successfully with minimal enamel damage. However, Polycrystalline brackets had slightly [less/more] damage than mono crystalline. Why?
more
iit was attributed to a more demanding cleanup
What is the major advantage of ceramic brackets?
esthetics
Name 6 disadvantages of ceramic brackets
- higher incidence of fracture during debonding (so don’t delegate removal of ceramic brackets)
- unable to withstand strong torque forces
- should be avoided in compromised teeth
- enamel wear can occur on opposing teeth
- causes nicks in the arch wire and increases friction
- Don’t use in pts who will undergo orthognathic surgery
What should you tell patients about ceramic brackets during a consult?
more chance of damage to enamel during debond
if brackets fracture could have more enamel damage
brackets fail more than metal brackets
Enamel damage from debonding of metal brackets occurs about __/10 times whereas ceramic occurs __/10 times. if RMGI is used instead of composite, about __/10 result in enamel damage.
1
3-4
2
Metal brackets fracture about __/10 times whereas ceramic brackets fracture about __/10 times
0
1-3
At present are we likely to encounter drugs that stimulate tooth movement?
No, not yet anyway
- Vitamin D (may have an effect?)
- prostaglandins DO accelerate tooth movement but injection of prostaglandins into PDL is very painful
- Relaxin (pregnancy hormone) reduces collagen synthesis and increases collagen breakdown, but its effect on tooth movement is still inconclusive
What are prostaglandins formed from? What are they?
Arachidonic acid, which is derived from phospholipids.
prostaglandins are mediators of inflammation, body temp, blood flow/clotting.
When are prostaglandins released and what causes their release?
They are released when COX2 breaks down arachidonic acid
Orthodontically, the release of PGE2 by COX 2 is activated when cells are mechanically deformed during the application of pressure on the PDL
What role do prostaglandins play in orthodontics?
prostaglandins (namely PGE2) stimulate osteoclastic and osteoblastic activity
Activates Rank-L from osteoblasts which causes a conversion of macrophages into activated osteoclasts on the compression side
True or false… when prostaglandins are inhibited it may slow down tooth movement
true
Prostaglandins activate ___ from ___ which causes a conversion of ___ into activated ___ on the ___ side of the PDL
Rank-L
macrophages
osteoclasts
compression
How can corticosteroids influence tooth movement? be specific
they reduce prostaglandin synthesis by inhibiting the formation of arachidonic acid (the precursor to prostaglandins)
less prostaglandins = less tooth movement
How do NSAIDs work and how could they influence tooth movement?
inhibit COX2 enzyme (responsible for converting arachidonic acid to prostaglandins)
less prostaglandins = less tooth movement
Describe how Tylenol works and how it could influence tooth movement.
Tylenol acts CENTRALLY, not peripherally, therefore tooth movement should NOT be affected
If orthodontic patients are taking NSAIDs PRN for ortho-related pain, would this likely affect tooth movement?
Nope. in this case, dosages are low and of short duration, thus unlikely to interfere with tooth movement
If pt was taking NSAIDs constantly for other condition such as arthritis, it could affect tooth movement because dosage and duration is increased
Since NSAIDs and Tylenol act differently, would a combo of the two provide better pain control than either one separately?
possibly. Current study going on in ortho rn. In other dental treatment though, the answer is yes.
What is the mechanism of bisphosphonates and how might they affect tooth movement?
Bisphosphonates are synthetic analogue of pyrophosphate, which bind to hydroxyapatite in bone in order ro prevent osteoporosis. they act as specific inhibitors of osteoclast-mediated bone resorption, so the modeling/remodling of bone during tooth movement is slower
Bisphosphonates are synthetic analogues of ___ which bind to ___ in bone in order to prevent ___
pyrophosphate
hydroxyapatite
osteoporosis
Why should elective procedures, such as extractions for ortho, be avoided for patients taking bisphosphonates?
elective extractions for orthodontic treatment can cause osteonecrosis of mandibular bone
What are some additional drugs that might affect orthodontic force?
tricyclic antidepressants
antiarrhythmic drugs
antimalarial drugs
methylxanthines
anticonvulsants (phenytoin)
tetracyclines
When teeth erupt or are moved, what happens to the alveolar bone?
when test erupt or are moved, they bring alveolar bone with them.
the only exception fo this is when the pt has active per dx.
What happens to the bone if a tooth is congenitally missing or extracted at an early age?
a permanent defect will occur unless another tooth is moved into that spot rather quickly
What can be down when a maxillary lateral incisor is missing and a prosthetic replacement is planned?
erupting teeth to bring bone with it
orthodontic tooth movement can create the alveolar bone needed to support an implant to replace a missing maxillary lateral incisor
have permanent canine erupt mesillay into the empty spot and then move distally to its proper position once the pt has stopped growing (this will stimulate bone formation in an area that would normally not occur)
Can bone support around periodontally involved teeth be improved by intruding teeth?
Normally when intruding teeth, the alveolar bone follows so the same amount of root is embedded in bone as before. There are reports of therapeutic intrusion resulting in smaller pockets (but the smaller pocket depths are due to an elongated junctional epithelium, not actual no bony support)
Can a tooth with normal periodontist be moved into an area of reduced bone height and maintain its attachment level?
“space closure in areas of major bone loss sometimes leads to an improvement in bone height if at least ONE wall of the periodontal pocket remains”
so, it may happen but cannot be predicted and promised to the pt. Good control of periodontal condition is key to success
According to the Bollen article, do we have evidence that ortho treatment has a positive effect on periodontal health?
no
What is the rationale for incorporating local injury to the alveolar process to accelerate tooth movement?
bone remodeling is accelerated during wound healing = teeth will move faster after local injury to the alveolar process
According to profit, how long after corticotomy would one expect that bone remodeling could be accelerated? corticocotomy is most effective in reduction of __ time.
2-4 months
key result is reduction in alignment time
What is the Kole technique associated with corticotomy?
teeth move within minutes/hours using a still arch wire that causes greenstick fractures of the bone at root apex. This causes rapid tipping movements, not bodily movement
What modifications to corticotomy have been proposed?
Piezocision - Incisions without flaps
Microperforations (propel)
What are some pros and cons to piezocision compared to corticotomy?
less invasive than corticotomy (small facial incisions with addition of bone graft)
can damage root, cause dehiscence, fenestration
What are some pros and cons to microperforations compared to corticotomy?
cost-risk ratio is favorable (no perio surgery)
lack of data regarding its effectiveness
What are profits conclusions regarding recommending corticotomy/piezocision/microperforations to accelerate tooth movement?
hesitant to recommend until further studies are completed
the benefits of reduction of time is beneficial, but the extent of the risks and its lack of evidence of effectiveness of treatment prevents the recommendation to be used commonly
In addition to corticotomy-like procedures, what are some other proposed approaches to accelerate tooth movement? comment on if it is effective or not
vibration (no definitive evidence)
tissue penetrating light (no definitive evidence)
ultrasound (plausible theory but lacking evidence)
low level laser therapy (unable to accelerate tooth movement)
electrical current (lacks evidence)
dentoalveolar periodontal distraction (lacks evidence)
