I posted a couple of items from "Practical Reviews in Orthodontics" which is a subscription service that I strongly recommend.It can be found here:
http://www.practicalreviews.com/Orthodontics/Journals/Practical-Reviews-in-Orthodontics-3105.aspx
Here is the description of the service (taken from the practical reviews website):
With the literally thousands of articles published annually in orthodontics, it is virtually an impossible task to sort through and read everything necessary to stay current. And there's the daunting task to even identify all the key clinical developments that are reported on in the numerous journals.
The physician-editors with Practical Reviews in Orthodontics sort through dozens of publications, find the most relevant studies, summarize them, and suggest ways to apply this information in practice. Most of the reviews are available to you in convenient audio format — allowing you to download this material to your laptop, MP3 player or almost any portable device.
Note: none of the material in this post was written by me. This post is taken directly from Practical Reviews. Hopefully, I have given the authors full credit.
An Evaluation of Clinicians' Choices When Selecting Archwires.
McNamara C, Drage KJ, et al: Eur J Orthod; 2010;32 (February): 54-59
Background: Many studies have looked at the stability of orthodontic results. In particular, attention has been paid to the form of the arch. Previous studies have found that using an arch form that maintains intercanine width, intermolar width, and arch length contributes to a stable result.
Objective: To determine the choices clinicians make when choosing arch wires during initial alignment and space closure.
Design: Survey.
Participants: 100 orthodontic practitioners within the Bristol Dental Hospital or who were contacted at local meetings were included in the survey. These consisted of consultant orthodontists (n=37), specialist practitioners (n=36), senior specialist registrars in orthodontics (n=10), and dentists with a special interest in orthodontics (n=17).
Methods: A questionnaire survey was distributed between November 2005 and March 2006. The questionnaire was divided into 2 parts, wires for initial alignment and wires for space closure in a Class I premolar extraction case. For initial alignment wires, clinicians were asked about arch-wire material, dimensions, trade name, arch form, and the importance of these factors when choosing a wire. For the space closure wires, clinicians were asked about arch-wire material, dimensions, use of study models for adaptation, use of symmetry charts, and the importance of these factors when using a wire.
Results: The 100 questionnaires returned represented a 92.6% response rate. A 0.022-inch slot was used by 99% of clinicians. For initial alignment wires, 1 clinician used 0.014 inch multi-stranded stainless steel, while the other 99% used nickel-titanium; of the 99%, 23 used classic NiTi (martensitic stable), 34 used super-elastic (austenitic active), and 34 used heat-activated (martensitic active) NiTi; 9 did not know what type of NiTi they used.
At this stage, arch form was found to be important by 16% of clinicians and the arch width by 23%.For space closure wires, 1 clinician used 0.018- x 0.025-inch NiTi, and the other 99% used stainless steel. All but 5 clinicians felt that adaptation to the canines was important, but there was great diversity on the other landmarks (incisors, premolars, or molars). In addition, the use of casts and symmetry charts varied.
Conclusions: A majority of clinicians felt that preserving a patient's pretreatment arch form was important in the later stages of treatment, but not for selection of initial alignment wires. No uniformity was found in the method used to preserve arch form.
Reviewer's Comments: Although this was not a scientific study of arch form or the ability to maintain arch form, it was interesting that most clinicians at least claimed to be concerned about preservation the lower arch intercanine width. Most of the clinicians rightly believed that arch form selection was less important for early alignment wires when tooth-to-tooth discrepancies override overall arch form characteristics. It would be interesting to look at actual treatment outcomes from this group of practitioners to see if the varied methods used during later treatment stages were equally successful in maintaining the lower arch form.(Reviewer–Brent E. Larson, DDS, MS).
Long-Term Effects of Rapid Maxillary Expansion Followed by Fixed Appliances.
Gurel HG, Memili B, et al: Angle Orthod; 2010;80 (January): 5-9
Background: Maxillary expansion is a routine procedure performed to correct narrow maxillary arch width and posterior cross-bite. We assume, as orthodontists, that our expansion will be stable long term, but is that assumption correct?
Objective: To evaluate the long-term changes in maxillary dental arch widths in patients who were treated with rapid maxillary expansion (RME) appliances followed by edgewise appliances.
Design: This was a retrospective analysis of the records of 41 patients who had been treated for maxillary constriction.
Methods: Maxillary dental casts were available at 4 time periods: before treatment, after maxillary expansion, after complete nonextraction orthodontic therapy, and approximately 5 years later. The maxillary intercanine, interpremolar, and intermolar widths were measured at all 4 intervals. These widths were then compared over time.
Results: The maxillary intermolar, interpremolar, and intercanine widths all increased during palatal expansion treatment. During the time of full-banded, edgewise orthodontic therapy, the intermolar, interpremolar, and intercanine widths decreased. After appliance removal, these widths continued to decrease, with the greatest decrease occurring in the intercanine width, which nearly reached its original pretreatment distance.
Conclusions:
A significant amount of relapse occurs after RME during a second phase of orthodontics, as well as long term.
Reviewer's Comments: I found the information in this study to be useful. I have had similar experiences in patients I have treated using RME followed by routine orthodontics. Long term, these arch widths tend to decrease with time. I believe it is probably due to the stretching of the palatal gingiva, which simply does not accommodate to these greater widths in all patients. It is good to be aware of this information before correction of posterior cross-bites and to consider long-term retention for patients who have been treated for significant palatal constriction.(Reviewer–Vincent G. Kokich, DDS, MSD).
Alignment Efficiency of Damon3 Self-Ligating and Conventional Orthodontic Bracket Systems: A Randomized Clinical Trial.
Scott P, DiBiase A, et al: Am J Orthod Dentofacial Orthop; 2008;134 (October): 470.e1-470.e8
Background: Self-ligating brackets have become increasingly popular. It has been suggested that the Damon3 self-ligating bracket encourages more rapid tooth alignment. In deciding to choose a bracket system, it is important to know if this is true.
Objective/Design: The purpose of this randomized, clinical trial was to compare the clinical efficiency of Damon3 self-ligating brackets with a conventional ligated bracket system during orthodontic tooth alignment.
Participants: The sample for this study consisted of 60 subjects (28 using Synthesis traditional brackets and 32 using Damon3 brackets). All subjects had a mandibular incisor irregularity of 5 to 12 mm, extraction of mandibular first premolars, and the absence of a complete overbite.
Interventions: The same series of initial arch wires ranging from a 0.014-in copper nickel titanium to a 0.019 x 0.025-in stainless steel arch wire were used for each group. Study casts were taken at the start of treatment, at the first arch wire change, and at placement of the final 0.019 x 0.025-in stainless steel arch wire. Little's Irregularity Index was used to measure changes in mandibular incisor alignment.
Results: No significant difference was noted in the initial rate of alignment for either bracket system. The influence of sex, age, and appliance type was statistically insignificant; however, the initial irregularity influenced the rate of tooth movement for both systems with greater irregularity related to more efficient tooth movement.
Conclusions:
Damon3 self-ligating brackets are no more efficient than conventionally ligated preadjusted brackets during tooth alignment.
Reviewer's Comments: Based on claims I have heard, I would have suspected that the Damon3 system would have been more efficient for mandibular incisor alignment. However, once again, it does not surprise me that commonly held orthodontic claims or theories are found to have no basis when exposed to objective research. There may be several good reasons to use the Damon3 self-ligating bracket system, such as reduced staff time in changing arch wires, but the rate of tooth movement is not one of them. (Reviewer–John S. Casko, DDS, MS, PhD).
Thursday, November 18, 2010
Sunday, November 14, 2010
Root Resorption
Reference-Evaluation of the risk of root resorption during orthodontic treatment. Eur J Orthod 10 (1): 30-38. Author: Eva Levander
Undiscovered root resorption is one of the main reasons for orthodontic litigation, so it is important that doctors performing ortho are aware of how to handle root resorption.
Informed consent- tell patients that there is a chance that treatment will have to be stopped early if the roots become damaged.
Panorex on all orthodontic patients 6 months into treatment
-Especially check upper front teeth
If all roots look normal, take follow up xray in about 1 year
Panorex 3 months into treatment on patients whose roots look fragile
-Fragile looking roots mean short, blunt, pipette shaped roots
Follow up xray in 6 months for fragile looking roots
If you discover root resorption, first stop active treatment for 3 months. Don’t take the braces off, but leave in a passive round wire with no forces (no rubber bands, chain, etc). Be especially concerned about forces on the upper cuspids, because forces on the cuspids can be easily transferred to the laterals, which seem to be the teeth most susceptible to resorption. After 3 months, get a p-a x-ray of teeth in question. If resorption has stopped (usually the case), continue treatment. If resorption has continued, remove the braces.
Undiscovered root resorption is one of the main reasons for orthodontic litigation, so it is important that doctors performing ortho are aware of how to handle root resorption.
Informed consent- tell patients that there is a chance that treatment will have to be stopped early if the roots become damaged.
Panorex on all orthodontic patients 6 months into treatment
-Especially check upper front teeth
If all roots look normal, take follow up xray in about 1 year
Panorex 3 months into treatment on patients whose roots look fragile
-Fragile looking roots mean short, blunt, pipette shaped roots
Follow up xray in 6 months for fragile looking roots
If you discover root resorption, first stop active treatment for 3 months. Don’t take the braces off, but leave in a passive round wire with no forces (no rubber bands, chain, etc). Be especially concerned about forces on the upper cuspids, because forces on the cuspids can be easily transferred to the laterals, which seem to be the teeth most susceptible to resorption. After 3 months, get a p-a x-ray of teeth in question. If resorption has stopped (usually the case), continue treatment. If resorption has continued, remove the braces.
Sunday, November 7, 2010
Question: On a deep bite patient, I can't put brackets on the lower anterior teeth because the bite is too deep. Do you usually open up the bite by using bite opening techniques on the upper arch before bracketing the lower, or do you open up the bite using occlusal composites and bracket the lower at the same time as the upper?
Answer: I usually bond composite to the occlusal surface of the lower molars and bracket the lowers, then gradually reduce the amount of composite as the bite opens.
Question: Often, when I finish a case I have overbite problems. Why is this happening? I am bracketing 4.0 mm from the incisal edge on all teeth except for upper laterals, on which I place 3.5mm from the incisal edge. Do you think that is my problem?
Answer:It is probably more a mechanics problem than a finishing problem. Brackets must be positioned based on the characteristics of the case, not some pre-set number. If the bite is deep pre-treatment the anterior brackets must be placed incisally and the premolar brackets must be positioned gingivally. This will allow you to open the bite and keep it open. During the wire progression, slightly overcorrect the overbite. Get it to 1 or 2mm. This is impossible to do if you position the brackets in the center when the pretreatment overbite is deep. Often many docs place the lower incisal brackets too gingivally in an effort to prevent occlusal interferences. This cannot be done; the bite will deepen. To avoid interferences, bond composite to the occlusal surfaces of the lower molars. Successful resolution of many aspects of malocclusions depend upon getting the bite open before progressing to other mechanics. If you are not getting overbite corrected, you will have difficulty in correcting other aspects (overjet, midline, spacing) of the malocclusion.
Question: When I bonded a LR3, the patient felt it interfering. Should I lower the bracket for now or should I open the bite temporarily by placing occlusal composite? Where should I place it?
Answer: Do not change bracket position. NEVER compromise bracket position. A small amount of composite bonded to the occlusal surface of the lower molars will help clear the bite.
TMJ/Ortho relationship statement (references available upon request)
1) There is no evidence to show that any type of orthodontic treatment done reasonably well has anything more than a minor effect on the health of the TMJ.
2) There is no evidence available that shows that performing orthodontic treatment for the main purpose of improving TMJ health is a valid reason to do treatment. Orthodontic treatment does not seem to predispose subjects to TMD problems nor is it indicated as an initial therapy for TMD patients.
3) The connection between occlusion and TMJ problems is a very weak connection. Patients should be told the following statement: I don't want to lead you to believe that straightening teeth will eliminate jaw problems. However, people with straight teeth do have fewer problems.
4) There are some occlusal factors that show a higher risk for future TMD problems. They are
Skeletal open bite
Overjet greater than 7mm
CR/ICP discrepancy greater than 4mm
Unilateral cross bite
6 or more permanent teeth missing
Absence of anterior guidance is also linked (weakly) to future TMD probs.
To help make sure the patient has the best odds of not developing future TMD problems, if possible these malocclusions with one or more of these characteristics should be corrected. But, to say a particular type of treatment is better from a TM health standpoint is not a valid statement.
Question: In extraction cases, why do you go through all of the wire progression before doing mechanics? I have heard some practitioners suggest to do mechanics at .020ss stage, then continue on with .019x.025 niti and stainless steel after the mechanics are complete. Also what is the difference if I use a posted wire and K-module from lateral hook to the molar hook to retract the anterior teeth vs. using chain elastics 3-3 and then hooking the
K-module to the canine hook and the molar hook? Which is better?
Answer: Wire progression is one of the hot topics in orthodontics today. Personally, I like to do all (or most) of my mechanics on rectangular wire because of the torque and arch width control it provides. Some docs prefer space closure on 020 because it is quicker and requires less anchorage control. They say that there is less friction with a round (as compared to a rectangular) wire (anecdotal evidence supports this statement, but no well designed studies have shown a significant difference in friction between the two methods). Those who close space on rectangular wire believe the arch width and torque control that filling the slot provides is more important than reducing friction. Take your pick (choose on a case by case basis) but know that most orthodontic graduate programs teach rectangular wire space closure.
The force system you use really doesn't matter as long as it is the correct force. I like 200-250g for space closure. Power chain starts off with an initial force that is too strong for efficient space closure. Then the force level rapidly decays, which is why my use of it is limited to areas where I don't have to stretch it too much. K modules provide a more consistent force over a long period of time, so the system you described is a good way to close space
.
No space closure method is necessarily better, but each system has advantages and disadvantages. Your job is to understand these and choose the method of space closure accordingly.
Question: I am trying to close a 1mm diastema in between 8 and 9 on a 30 year old patient. Can I bracket 3-3 only or do I have to band the molars as well? Also, do I have to go through all of the wire progression?
Answer: Bracketing 3-3 (or 2-2 or even 1-1) only is often appropriate when closing a diastema. A limited wire progression is also OK. Finally, an occlusally directed gable bend placed between the centrals when closing the space will help place the roots in a position where relapse may not as easily occur.
Question: After bonding a LR2 I could not deflect the wire enough to engage the wire fully into the slot. Can I bypass this tooth and pack open coil to create a little more space?
Answer: Bypassing teeth on initial tie-in is an OK thing to do. You could also try a lighter wire (014 or 012 niti) instead of 016 niti.
Question: I have a 18y/o female patient who has a deficient maxilla and high palate. She has a bilateral posterior crossbite, and has Class I molars. I plan to use rapid palatal expander. Is it appropriate? If so, how many turns of screw are necessary?
Answer:I don't think it is appropriate to use an RPE in a physically mature patient, unless you perform surgically assisted rapid palatal expansion. If you must expand, use an appliance that tips teeth, as that is all you are going to get anyway. I like the quad helix for this situation.
Question: To perform an arch width analysis on the mandible, what is the distance I should measure according to USDI guidelines? Do I measure at the first or second premolars?
Answer: USDI guidelines for ideal upper arch width use buccal pit to buccal pit the first bicuspids. The measurement is 6 to 8 mm wider (depending on facial type) of the sum of the width of 4 incisors compared to the width of pit to pit. Width of the mandibular arch is more controversial. Not a lot of quantitative measurements exist. My personal opinion (supported by the vast majority of ortho literature) is that mandibular expansion in an adult (in fact, on any child over 9 years old) is not indicated. If you choose to expand the lower arch, you should prescribe lifetime retention.
Answer: I usually bond composite to the occlusal surface of the lower molars and bracket the lowers, then gradually reduce the amount of composite as the bite opens.
Question: Often, when I finish a case I have overbite problems. Why is this happening? I am bracketing 4.0 mm from the incisal edge on all teeth except for upper laterals, on which I place 3.5mm from the incisal edge. Do you think that is my problem?
Answer:It is probably more a mechanics problem than a finishing problem. Brackets must be positioned based on the characteristics of the case, not some pre-set number. If the bite is deep pre-treatment the anterior brackets must be placed incisally and the premolar brackets must be positioned gingivally. This will allow you to open the bite and keep it open. During the wire progression, slightly overcorrect the overbite. Get it to 1 or 2mm. This is impossible to do if you position the brackets in the center when the pretreatment overbite is deep. Often many docs place the lower incisal brackets too gingivally in an effort to prevent occlusal interferences. This cannot be done; the bite will deepen. To avoid interferences, bond composite to the occlusal surfaces of the lower molars. Successful resolution of many aspects of malocclusions depend upon getting the bite open before progressing to other mechanics. If you are not getting overbite corrected, you will have difficulty in correcting other aspects (overjet, midline, spacing) of the malocclusion.
Question: When I bonded a LR3, the patient felt it interfering. Should I lower the bracket for now or should I open the bite temporarily by placing occlusal composite? Where should I place it?
Answer: Do not change bracket position. NEVER compromise bracket position. A small amount of composite bonded to the occlusal surface of the lower molars will help clear the bite.
TMJ/Ortho relationship statement (references available upon request)
1) There is no evidence to show that any type of orthodontic treatment done reasonably well has anything more than a minor effect on the health of the TMJ.
2) There is no evidence available that shows that performing orthodontic treatment for the main purpose of improving TMJ health is a valid reason to do treatment. Orthodontic treatment does not seem to predispose subjects to TMD problems nor is it indicated as an initial therapy for TMD patients.
3) The connection between occlusion and TMJ problems is a very weak connection. Patients should be told the following statement: I don't want to lead you to believe that straightening teeth will eliminate jaw problems. However, people with straight teeth do have fewer problems.
4) There are some occlusal factors that show a higher risk for future TMD problems. They are
Skeletal open bite
Overjet greater than 7mm
CR/ICP discrepancy greater than 4mm
Unilateral cross bite
6 or more permanent teeth missing
Absence of anterior guidance is also linked (weakly) to future TMD probs.
To help make sure the patient has the best odds of not developing future TMD problems, if possible these malocclusions with one or more of these characteristics should be corrected. But, to say a particular type of treatment is better from a TM health standpoint is not a valid statement.
Question: In extraction cases, why do you go through all of the wire progression before doing mechanics? I have heard some practitioners suggest to do mechanics at .020ss stage, then continue on with .019x.025 niti and stainless steel after the mechanics are complete. Also what is the difference if I use a posted wire and K-module from lateral hook to the molar hook to retract the anterior teeth vs. using chain elastics 3-3 and then hooking the
K-module to the canine hook and the molar hook? Which is better?
Answer: Wire progression is one of the hot topics in orthodontics today. Personally, I like to do all (or most) of my mechanics on rectangular wire because of the torque and arch width control it provides. Some docs prefer space closure on 020 because it is quicker and requires less anchorage control. They say that there is less friction with a round (as compared to a rectangular) wire (anecdotal evidence supports this statement, but no well designed studies have shown a significant difference in friction between the two methods). Those who close space on rectangular wire believe the arch width and torque control that filling the slot provides is more important than reducing friction. Take your pick (choose on a case by case basis) but know that most orthodontic graduate programs teach rectangular wire space closure.
The force system you use really doesn't matter as long as it is the correct force. I like 200-250g for space closure. Power chain starts off with an initial force that is too strong for efficient space closure. Then the force level rapidly decays, which is why my use of it is limited to areas where I don't have to stretch it too much. K modules provide a more consistent force over a long period of time, so the system you described is a good way to close space
.
No space closure method is necessarily better, but each system has advantages and disadvantages. Your job is to understand these and choose the method of space closure accordingly.
Question: I am trying to close a 1mm diastema in between 8 and 9 on a 30 year old patient. Can I bracket 3-3 only or do I have to band the molars as well? Also, do I have to go through all of the wire progression?
Answer: Bracketing 3-3 (or 2-2 or even 1-1) only is often appropriate when closing a diastema. A limited wire progression is also OK. Finally, an occlusally directed gable bend placed between the centrals when closing the space will help place the roots in a position where relapse may not as easily occur.
Question: After bonding a LR2 I could not deflect the wire enough to engage the wire fully into the slot. Can I bypass this tooth and pack open coil to create a little more space?
Answer: Bypassing teeth on initial tie-in is an OK thing to do. You could also try a lighter wire (014 or 012 niti) instead of 016 niti.
Question: I have a 18y/o female patient who has a deficient maxilla and high palate. She has a bilateral posterior crossbite, and has Class I molars. I plan to use rapid palatal expander. Is it appropriate? If so, how many turns of screw are necessary?
Answer:I don't think it is appropriate to use an RPE in a physically mature patient, unless you perform surgically assisted rapid palatal expansion. If you must expand, use an appliance that tips teeth, as that is all you are going to get anyway. I like the quad helix for this situation.
Question: To perform an arch width analysis on the mandible, what is the distance I should measure according to USDI guidelines? Do I measure at the first or second premolars?
Answer: USDI guidelines for ideal upper arch width use buccal pit to buccal pit the first bicuspids. The measurement is 6 to 8 mm wider (depending on facial type) of the sum of the width of 4 incisors compared to the width of pit to pit. Width of the mandibular arch is more controversial. Not a lot of quantitative measurements exist. My personal opinion (supported by the vast majority of ortho literature) is that mandibular expansion in an adult (in fact, on any child over 9 years old) is not indicated. If you choose to expand the lower arch, you should prescribe lifetime retention.
Friday, May 7, 2010
More Questions
How do you decide when to use arch wire curves as opposed to tip-back bends when the bite needs to be opened?
The amount of gingival display often dictates what method of bite opening to use. If the patient has a gummy smile I would rather intrude incisors (tip-backs do this more efficiently than curves) which results in a reduction of gingival display. If the smile is not gummy, erupting molars (curves often do this more efficiently than tip backs) will open the bite without reducing the gingival display.
It is easy to envision that a toe-in bend for maxillary molars helps correct the mesio-lingual rotation of the molars. But how does the toe-in bend applied to the mandibular molars counteract the lingual movement which is often a consequence of eruptive forces produced by tip backs? Also, do you do the toe-in and tip-back bends together or one at a time?
A toe-in results in buccal crown movement. An eruptive force (the tip back) in one plane of space becomes a buccal force (the toe in) in another plane of space. Look at the photo, courtesy of Dr. Tom Mulligan.
Although some practitioners use both bends simultaneously, I don't. I like to keep my forces as simple as possible. The toe in is used to counter the potential negative side effect of bite opening, which is lingual crown movement. If the side effect isn’t expressed when using the tip back, there is no need for a toe-in. So I wait to see if I need it.
Remember, when using toe-in or tip-back bends, for eruptive(tip-back) or horizontal (toe-in) forces to be produced, the bends must be asymmetric. In other words, the distance between where the wire is bent and where the wire is first engaged must be different on both sides of the wire.If this condition is met, use Mulligan's long and short segment rule (see photos or go to http://www.commonsensemechanics.com/CourseContent.htm )to determine the forces that will be imparted by the wire.
Now I’m a little confused. The toe-in is used to prevent rolling in of the mandibular molars. Why does this rolling in of the mandibular molars occur?
A side-effect of molar eruption (or any extrusive force for that matter) is lingual crown torque. This force often results in lingual molar movement. Because the wires used for tip backs (usually .016 or.020 stainless steel) are round, in a .022 slot no torque control occurs. Additionally, if rectangular wires are used, the pre-adjusted appliance prescription for the lower molars has lingual crown torque built in. These factors contribute to rolling in, or lingual tipping, of the lower molars. A toe-in bend counteracts these tendencies by providing a buccal force. Ideally, the "bad" forces are cancelled by the "good" forces and the net result is a molar that is upright, not rolled in.
I have another question for you: Why do practitioners who use utility arches expand the upper arch by 5-10 mm by flattening the anterior bridge to correct ClassII Div 1 and 2 patients? Is the expansion necessary?
Upper arch expansion combined with distally rotating the upper molars has been a technique used to correct Class II for over a century (It is often done when using headgear by adjusting the inner bow). The expansion creates the environment where the lower arch can be positioned forward (many ClassII’s are the result of a narrow upper arch which results in the lower arch being positioned, or trapped, distally). This is combined with distal rotation of the upper 1st molar, which places the palatal cusp of the upper 6 in a more anterior position. In ideal occlusion, the upper 6 palatal cusp occludes with the central pit of the lower 6. When the upper 6 palatal cusp is positioned more anteriorly, the lower molar (and hence the whole lower arch) is guided forward. The expanded upper arch allows the mandible to reposition forward, which results in Class II correction.
What’s the easiest way to flare lower incisors forward to gain arch length?
You can do this by manipulation of a utility arch, which has been popularized by Dr. Len Carapezza (http://www.igdpd.com). You could also use a straight wire, leaving the 3's, 4's and 5's unbracketed, packing coil between the 2's and 6's. Make the coil about 2mm longer than the distance between the distal of the bracket on the 2, and the mesial of the bracket on the 6. The force will push the anteriors forward and the molars back. The anterior teeth move forward much more easily than the molars distalize, so the net effect is forward incisor movement. Every month, pack a new piece of coil which is 2mm longer than the coil used in the previous month. Continue until the incisors are where you want them. The same effect can also be achieved by placing stops in the arch wire near the molars so there is a little extra wire length from molar to molar. If you do it this way, you must change the arch wire to gain additional forward movement of the incisors, so this method may be more cumbersome than packing coil.
I have a question about molar uprighting. I have a few adult patients that have lost their lower first molars and I would like to upright their 2nd molars. In order to do this could I simply place a tip back bend just distal to the 2nd premolars rather than just mesial to the molar band? Any suggestions you have on how to upright molars would be greatly appreciated.
Molar uprighting is tough. In theory a center bend (technically an occlusally directed gable bend) will parallel the roots and all vertical forces will cancel. In reality it is very difficult to make the bend a center bend because the bracket position- and hence wire angle of entry- is different on the teeth adjacent to the bend (one bracket is relatively straight, the other is tipped). This contributes to making the bend asymmetric. Unlike a center bend, where vertical forces cancel, the asymmetric bend leads to expression of vertical forces. The big challenge in molar uprighting is to prevent eruption of the molar which often contributes to unwanted bite opening.
Uprighting without eruption occurs with a center bend. You may also get eruption because the bend is usually not precisely a center bend.. Occlusal adjustments must be made so the bite doesn't excessively open. Often, the molar needs to be crowned because so much eruption occurs.
Orthodontists have designed uprighting springs that mitigate the eruptive forces. They are kind of hard to use. Many are now using temporary anchorage (TAD's) to get a more direct force on the molar.
All in all, uprighting is tough. Don't promise your patient much, because you never really know how successful it will be. A combination of a small amount of uprighting, followed by a small amount of mesial movement repeated over and over can yield acceptable results. This is cumbersome and time consuming.
I have a case where, during the initial stage of leveling and aligning, I cannot place the bracket on tooth # 4 in an ideal position. The tooth is blocked out of the arch and also slightly under erupted. Should I continue on to the next stage and wait for this tooth to come in a little more?
Don't go up the wire progression until you get that tooth aligned. Try packing coil for a month; that should free up the tooth to let it erupt. After creating space, get a bracket on it as best you can. If you have to place the bracket too occlusally, thread the initial arch wire (usually this is .012, .014, or .016 nickel titanium) under the gingival tie wings and engage the wire as usual on all the other teeth. This will help erupt the tooth. After a month, reposition the bracket if necessary and tie it in as usual. Once it is aligned, you can move up the wire progression.
I am working on a case where I extracted lower 1st bicuspids to camouflage a Class III occlusion. You suggested to do a tieback right away with .016Niti. Will this move the canine distally into the extraction site? If so, why do I not wait until I am in stronger wire(as suggested in some literature) such as 020ss or rectangular wire?. I have been trying the tieback for about 3 months and still do not see any significant changes. Should I use chain from 3-6 for a month or two instead of the tieback? Can I use the tieback and the power chain from 3-6 at the same time?
Thanks again for all your help.
The tieback (from here on I will refer to it as a laceback) prevents forward movement of incisors during the initial stages of treatment. Without lacebacks in extraction cases, aligning of a crowded arch results in anterior movement of incisors as the crowding is relieved.(For examples of laceback use, see here http://multimedia.3m.com/mws/mediawebserver?mwsId=66666UuZjcFSLXTtM8TamXTyEVuQEcuZgVs6EVs6E666666-- ) This is especially important on the lower arch in ClassIII cases because anterior lower incisor movement is contraindicated. In these cases, you probably won't see much retraction of the canine (it has to do with lack of tip built into preadjusted lower incisor brackets) but the incisors will not move forward. Using a chain instead of a steel tie is not a good idea because the chain is too powerful. It will tip the teeth into the extraction site which makes leveling more difficult.
Once you have completed the initial aligning, remove the laceback and go through a wire progression. When you get into a rigid wire, begin space closure. I prefer en-masse space closure; that is, I retract all 6 anteriors together. In most cases, close space on 019x025 stainless steel; however in many ClassIII's I use .020 stainless steel to do space closure in the lower arch. Space closure mechanics on round will result in de-torquing of the anterior teeth. This is usually beneficial on the lower arch in ClassIII cases because the de-torqued incisors help mask the underlying skeletal ClassIII occlusion.
The amount of gingival display often dictates what method of bite opening to use. If the patient has a gummy smile I would rather intrude incisors (tip-backs do this more efficiently than curves) which results in a reduction of gingival display. If the smile is not gummy, erupting molars (curves often do this more efficiently than tip backs) will open the bite without reducing the gingival display.
It is easy to envision that a toe-in bend for maxillary molars helps correct the mesio-lingual rotation of the molars. But how does the toe-in bend applied to the mandibular molars counteract the lingual movement which is often a consequence of eruptive forces produced by tip backs? Also, do you do the toe-in and tip-back bends together or one at a time?
A toe-in results in buccal crown movement. An eruptive force (the tip back) in one plane of space becomes a buccal force (the toe in) in another plane of space. Look at the photo, courtesy of Dr. Tom Mulligan.
Although some practitioners use both bends simultaneously, I don't. I like to keep my forces as simple as possible. The toe in is used to counter the potential negative side effect of bite opening, which is lingual crown movement. If the side effect isn’t expressed when using the tip back, there is no need for a toe-in. So I wait to see if I need it.
Remember, when using toe-in or tip-back bends, for eruptive(tip-back) or horizontal (toe-in) forces to be produced, the bends must be asymmetric. In other words, the distance between where the wire is bent and where the wire is first engaged must be different on both sides of the wire.If this condition is met, use Mulligan's long and short segment rule (see photos or go to http://www.commonsensemechanics.com/CourseContent.htm )to determine the forces that will be imparted by the wire.
Now I’m a little confused. The toe-in is used to prevent rolling in of the mandibular molars. Why does this rolling in of the mandibular molars occur?
A side-effect of molar eruption (or any extrusive force for that matter) is lingual crown torque. This force often results in lingual molar movement. Because the wires used for tip backs (usually .016 or.020 stainless steel) are round, in a .022 slot no torque control occurs. Additionally, if rectangular wires are used, the pre-adjusted appliance prescription for the lower molars has lingual crown torque built in. These factors contribute to rolling in, or lingual tipping, of the lower molars. A toe-in bend counteracts these tendencies by providing a buccal force. Ideally, the "bad" forces are cancelled by the "good" forces and the net result is a molar that is upright, not rolled in.
I have another question for you: Why do practitioners who use utility arches expand the upper arch by 5-10 mm by flattening the anterior bridge to correct ClassII Div 1 and 2 patients? Is the expansion necessary?
Upper arch expansion combined with distally rotating the upper molars has been a technique used to correct Class II for over a century (It is often done when using headgear by adjusting the inner bow). The expansion creates the environment where the lower arch can be positioned forward (many ClassII’s are the result of a narrow upper arch which results in the lower arch being positioned, or trapped, distally). This is combined with distal rotation of the upper 1st molar, which places the palatal cusp of the upper 6 in a more anterior position. In ideal occlusion, the upper 6 palatal cusp occludes with the central pit of the lower 6. When the upper 6 palatal cusp is positioned more anteriorly, the lower molar (and hence the whole lower arch) is guided forward. The expanded upper arch allows the mandible to reposition forward, which results in Class II correction.
What’s the easiest way to flare lower incisors forward to gain arch length?
You can do this by manipulation of a utility arch, which has been popularized by Dr. Len Carapezza (http://www.igdpd.com). You could also use a straight wire, leaving the 3's, 4's and 5's unbracketed, packing coil between the 2's and 6's. Make the coil about 2mm longer than the distance between the distal of the bracket on the 2, and the mesial of the bracket on the 6. The force will push the anteriors forward and the molars back. The anterior teeth move forward much more easily than the molars distalize, so the net effect is forward incisor movement. Every month, pack a new piece of coil which is 2mm longer than the coil used in the previous month. Continue until the incisors are where you want them. The same effect can also be achieved by placing stops in the arch wire near the molars so there is a little extra wire length from molar to molar. If you do it this way, you must change the arch wire to gain additional forward movement of the incisors, so this method may be more cumbersome than packing coil.
I have a question about molar uprighting. I have a few adult patients that have lost their lower first molars and I would like to upright their 2nd molars. In order to do this could I simply place a tip back bend just distal to the 2nd premolars rather than just mesial to the molar band? Any suggestions you have on how to upright molars would be greatly appreciated.
Molar uprighting is tough. In theory a center bend (technically an occlusally directed gable bend) will parallel the roots and all vertical forces will cancel. In reality it is very difficult to make the bend a center bend because the bracket position- and hence wire angle of entry- is different on the teeth adjacent to the bend (one bracket is relatively straight, the other is tipped). This contributes to making the bend asymmetric. Unlike a center bend, where vertical forces cancel, the asymmetric bend leads to expression of vertical forces. The big challenge in molar uprighting is to prevent eruption of the molar which often contributes to unwanted bite opening.
Uprighting without eruption occurs with a center bend. You may also get eruption because the bend is usually not precisely a center bend.. Occlusal adjustments must be made so the bite doesn't excessively open. Often, the molar needs to be crowned because so much eruption occurs.
Orthodontists have designed uprighting springs that mitigate the eruptive forces. They are kind of hard to use. Many are now using temporary anchorage (TAD's) to get a more direct force on the molar.
All in all, uprighting is tough. Don't promise your patient much, because you never really know how successful it will be. A combination of a small amount of uprighting, followed by a small amount of mesial movement repeated over and over can yield acceptable results. This is cumbersome and time consuming.
I have a case where, during the initial stage of leveling and aligning, I cannot place the bracket on tooth # 4 in an ideal position. The tooth is blocked out of the arch and also slightly under erupted. Should I continue on to the next stage and wait for this tooth to come in a little more?
Don't go up the wire progression until you get that tooth aligned. Try packing coil for a month; that should free up the tooth to let it erupt. After creating space, get a bracket on it as best you can. If you have to place the bracket too occlusally, thread the initial arch wire (usually this is .012, .014, or .016 nickel titanium) under the gingival tie wings and engage the wire as usual on all the other teeth. This will help erupt the tooth. After a month, reposition the bracket if necessary and tie it in as usual. Once it is aligned, you can move up the wire progression.
I am working on a case where I extracted lower 1st bicuspids to camouflage a Class III occlusion. You suggested to do a tieback right away with .016Niti. Will this move the canine distally into the extraction site? If so, why do I not wait until I am in stronger wire(as suggested in some literature) such as 020ss or rectangular wire?. I have been trying the tieback for about 3 months and still do not see any significant changes. Should I use chain from 3-6 for a month or two instead of the tieback? Can I use the tieback and the power chain from 3-6 at the same time?
Thanks again for all your help.
The tieback (from here on I will refer to it as a laceback) prevents forward movement of incisors during the initial stages of treatment. Without lacebacks in extraction cases, aligning of a crowded arch results in anterior movement of incisors as the crowding is relieved.(For examples of laceback use, see here http://multimedia.3m.com/mws/mediawebserver?mwsId=66666UuZjcFSLXTtM8TamXTyEVuQEcuZgVs6EVs6E666666-- ) This is especially important on the lower arch in ClassIII cases because anterior lower incisor movement is contraindicated. In these cases, you probably won't see much retraction of the canine (it has to do with lack of tip built into preadjusted lower incisor brackets) but the incisors will not move forward. Using a chain instead of a steel tie is not a good idea because the chain is too powerful. It will tip the teeth into the extraction site which makes leveling more difficult.
Once you have completed the initial aligning, remove the laceback and go through a wire progression. When you get into a rigid wire, begin space closure. I prefer en-masse space closure; that is, I retract all 6 anteriors together. In most cases, close space on 019x025 stainless steel; however in many ClassIII's I use .020 stainless steel to do space closure in the lower arch. Space closure mechanics on round will result in de-torquing of the anterior teeth. This is usually beneficial on the lower arch in ClassIII cases because the de-torqued incisors help mask the underlying skeletal ClassIII occlusion.
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