Thursday, November 18, 2010

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:

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.


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.


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).

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.

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.