JCO You advocate preorthodontic guidance as well as Begg treatment in the mixed dentition as a part of early intervention.
DR. WAGERS Yes. Young patients who have a developing malocclusion fall into two general categories in our office. They are either preorthodontic guidance cases or mixed dentition corrective treatment cases. Preorthodontic guidance is simply the management of a malocclusion, prior to banded treatment of the case in the mixed or permanent dentition. To us, preorthodontic guidance means doing as much tooth eruption guidance as possible to minimize the amount of future banded orthodontic treatment. For example, in a Class I discrepancy case, if we remove first premolar teeth well ahead of their eruptive time, the cuspids will move into a near normal position as they are erupting. The amount of orthodontic movement will have been minimized in that case. These cases, as a group, will average 16 months of one-phase treatment, which means that some of them finish in less than a year.
JCO Do you use any appliances in your preorthodontic guidance?
DR. WAGERS We use fixed lingual arches with springs, or removable appliances with auxiliaries to guide individual teeth to erupt close to their proper position. Occasionally, we place a space maintainer as a preventive procedure. The prevention of malocclusion is extremely limited. Today, I am convinced that arch size to tooth size discrepancy is the major cause of malocclusion and I do not know how to prevent this.
Over the years, we used cervical gear, both orthopedically and orthodontically, bite plates, bite guides, habit reminders, lip bumpers, and many other fixed and removable appliances. Finally, we settled on the early corrective approach with full bands in the mixed dentition for total arch management. When this was not necessary, a preorthodontic guidance approach was used. We use the simplest method possible to do simple tooth guidance to maintain space.
JCO How much do you aim to accomplish in the mixed dentition and how much is left for treatment after the permanent teeth have erupted?
DR. WAGERS Mixed dentition banded treatment must be done in two phases and any appliance may be used. We use the Begg appliance. In the first phase of mixed dentition Begg treatment we attempt to finish Stage I treatment goals and about a third or one-half of Stage II treatment goals. We must open or close the bite and move the anterior teeth to an end-to-end position. It is not possible to close all the spaces, since all permanent teeth have not erupted. We retract protrusive incisors, trying to anticipate the space requirement of the unerupted teeth. We prefer to overclose rather than to leave space in our estimated goal for space closure. The anterior teeth will recover and move back to the labial by the time appliances are needed in the second phase. Then we will be
finishing the last portion of Begg Stage II and proceed into Stage III as usual.
JCO If mixed dentition Begg treatment carries part way through Stage II, are the teeth at poor inclinations for a long period of time?
DR. WAGERS No, because the incisors tend to upright themselves. In fact, by the time Stage III is achieved in the 2nd phase of 2-phase treatment, there is less third stage torquing and uprighting than usual. The tooth inclinations at the beginning of the second phase are not as accentuated as they are in 1-phase treatment. The roots reposition and will even torque some during the rest period. The ANB difference will often be less when treatment begins again in the second phase. This can be due to chin growth. Stage II may take a little longer time if space has opened, but Stage III generally takes a little less time in mixed dentition 2-phase treatment cases, because of this uprighting in the rest period between phases of treatment.
One of the big worries of those who don't do mixed dentition treatment is the fear that they may lose too much anchorage by having treated in this period. The accompanying chart made from a survey of twenty-five mixed dentition treatment patients' cephalometric radiographs shows that of the molar anchorage you lose, about half is lost in the first period and half in the second period. The total anchorage loss is just about what would be lost if banded treatment were undertaken at an older age in just one period.
JCO Is there any more of a lower molar anchorage problem in nonextraction mixed dentition treatment, because you are correcting the molar relationship at that time?
DR. WAGERS This doesn't seem to be a problem in mixed dentition nonextraction cases. But, I'll admit we're conservative and on rare occasions will use a fixed lingual archwire as a safeguard against loss of anchorage in these cases.
JCO Is banding the same in mixed dentition extraction and nonextraction treatment?
DR. WAGERS In extraction cases, we have removed the deciduous cuspids, first deciduous molars, and the first bicuspids. In nonextraction cases, we leave these teeth out of the banding arrangement. Consequently, we use the same banding arrangement. The only difference is that we may use a fixed lingual archwire on nonextraction cases. We band the permanent first molars, deciduous second molars, and the central and lateral incisors in either case.
JCO Do you use identical bends in the first archwire in mixed dentition and permanent dentition treatment?
DR. WAGERS
In mixed dentition, the distance between the bracket on the deciduous molar band and the first molar tube is a little greater, which means that the anchor bend might be placed closer to the molar than it is in the permanent dentition. The angulation is the same. The bite opens more quickly in mixed dentition cases. Some bites relapse just as quickly in the rest period. This must be taken in consideration when the orthodontist starts the last phase of treatment. Problems such as habits and muscle tenseness that will affect bites can be observed during the rest period. This allows better assessment of the course to take in the last phase of treatment.
JCO As far as the mechanics is concerned, do you use a first stage arch running from the four anteriors to the six-year molars, with tipbacks?
DR. WAGERS Yes, but it passes through a loose attachment on second deciduous molars. We use any deviation or arch loops necessary to get the teeth into alignment and then on subsequent adjustments change to a straight archwire. If there is a tendency for the teeth to spread out along the archwire, we will use an intramaxillary elastic or an elastic ligature, from lateral incisor to lateral incisor. After the spaces are closed, we will frequently use stops distal to the lateral brackets, just to hold them while the protrusive retraction continues. We retract until the lower incisors are a couple of millimeters behind the APo line and the upper incisors are moved back to an end-to-end position with the lower incisors.
JCO Do you always band both arches?
DR. WAGERS Yes, we always band both arches.
JCO Do you always use intermaxillary elastics?
DR. WAGERS Yes, always and frequently intramaxillary elastics as well. But, we never use a bite plate or cervical gear. Only Begg full-banded appliances.
JCO When you treat first stage, in the mixed dentition, is bite opening easier or about the same?
DR. WAGERS First stage is generally much easier. There is a great deal of improvement in the first 4-5 months and the bite will open in the first 3-4 months. The whole first phase, which includes some Stage II Begg goals, only averages 9 months.
JCO What maintains it, in the interim or rest period, to prevent the bite from closing back down?
DR. WAGERS Some bites do close, but most do not. We open the bite more in the first phase today than we did in years past. Also, we may move incisors past an edge-to-edge position. If we have a patient with strong musculature and a closed bite to begin with, it is very likely the patient'sbite will close again in the rest period. The bite will have to be opened up again in the second phase of treatment. Once the bite is opened up again in that second phase, the majority of them do not have a tendency to close again. There must be more torquing of the anterior incisors to guard against this history of bite closure. I believe stability is better in the cases treated in mixed dentition in two phases, than comparable cases treated in the permanent dentition.
JCO Are high angle and low angle cases handled differently, in mixed dentition treatment?
DR. WAGERS In our experience, a high angle case can be analyzed as a high angle case at 6 years of age and that pattern and high angulation doesn't change by 14 years of age. We treat it in the mixed dentition the same as in the permanent dentition. There is not much vertical room in the posterior region in that type of case, due to the high angle of rise of the mandible to the maxillae. This lack of vertical room keeps long and large roots from being moved up that plane. The decision to remove teeth is likely to be made in high angle cases, whether mixed dentition or permanent dentition. In a low angle case, you are as likely to consider it as nonextraction in a mixed dentition case as in a permanent dentition case. In low angle cases, there is more room to move tooth roots
back into the posterior regions.
JCO Do you treat mixed dentition cases differently in open bites?
DR. WAGERS We treat them the same as in the permanent dentition. Open bite cases are frequently high angle cases and are more likely to need extraction of teeth for correction at any age.
Open bite non-discrepancy cases that are Class II, not needing extraction of bicuspids, can also be successfully treated in two-phase mixed dentition correction. Positioners are used prior to retainers almost routinely in these cases. This seems to help in keeping the bite closed posttreatment.
JCO Do you tend to not use Class II elastics on open bite cases?
DR. WAGERS We use Class II elastics generally, since open bite cases are usually protrusive. Once we reduce the protrusion, in the first period, most open bites don't seem to reopen in the rest period. If they should reopen, we reanalyze the case and consider an eight-tooth extraction solution. This will occur no more often than in permanent dentition cases.
JCO The eruptive pattern is so varied that you have some 7-year-olds who need treatment, while others will have a comparable situation at 10. What do you consider the optimum time for mixed dentition treatment?
DR. WAGERS Anytime that there is a severe protrusion. We generally wait for the four incisors in both arches to erupt before we make an orthodontic evaluation. Years ago, we treated extreme cases with only two incisors present. It can be done, but it is more difficult and sometimes takes a little longer. So, now we wait for eruption of four incisors in both arches before attempting treatment.
We have treated a few extremely severe deciduous arch malalignments at 3-4 years of age. Some were Class III cases and some Class II cases. There is better response in the deciduous dentition in the Class III cases than at any other time. In a very small number of patients, we have treated in three periods -- deciduous, mixed and permanent dentition. The dental arches were so far out of position in the deciduous dentition that the patients could not masticate food.
JCO And, you feel comfortable with the extraction decision in the mixed dentition stage?
DR. WAGERS The arch size perimeter anterior to the first molar is decided by the time of its eruption. Consequently, from that point on there is only arch length growth to be gained in the second molar area. The orthodontist can make a valid judgment as to whether or not there is enough space for the permanent tooth material trying to erupt. If there is not enough space, he should consider the removal of teeth. Many of the cases treated in the mixed dentition are extraction cases and many of the preorthodontic guidance cases involve extractions.
[show_img]631-jco-img-0.jpg[/show_img]To illustrate the use of bands in the first phase and subsequent adjustments, here is an 8-year-old boy (K.G.) with a mixed dentition treatment indication, due to a severe protrusion and a tooth size to arch size discrepancy.
[show_img]631-jco-img-2.jpg[/show_img]There had been some preorthodontic guidance procedures a year earlier, with removal of the deciduous molars.
[show_img]631-jco-img-3.jpg[/show_img]His first deciduous molars were removed first, to encourage the premature eruption of the first bicuspids, which were trapped by the severe discrepancy. Sometimes, you can remove the first deciduous molars and get an early eruption of the first bicuspids. That didn't happen in this case and we still had to have the first bicuspids removed, before eruption. We don't ordinarily do that unless the cuspid looks as if it is going to be deviated by the crowding. We palpate the maxillary canine area. Based on its prominence and on the appearance of its root formation, we make a decision on the extraction of bicuspids. I see no reason to permit the canines to erupt greatly deviated to the labial by crowding in a discrepancy case. In this case, even though the lower incisor was 4mm behind the APo line, it was an extraction case, because there was such a discrepancy between tooth size and arch size.
Banded appliances were placed, after the extraction of the first bicuspids, overlying deciduous cuspids and first deciduous molars; with first stage Begg archwires having the necessary loops to align the anterior teeth .
[show_img]631-jco-img-4.jpg[/show_img]JCO You have no qualms in this situation, about moving anterior teeth back against the unerupted cuspids?
DR. WAGERS None. The cuspid is displaced back into the extraction space. We have never seen lateral incisor root resorption, as a result of this movement, except in cases needing extraction. This causes cuspids to crowd the lateral incisor roots too much. If there is room made behind the cuspids, they take the line of the least resistance and, as the lateral incisors are moved back against them, the cuspids will erupt in the extraction space. In the case we are looking at, we removed the looped
archwires in less than four weeks and placed straight archwires.
We used an elastic from lateral to lateral, to keep the teeth from drifting apart, and to close space. As soon as the space is closed, we put stops in the archwire to avoid using the elastic further.
[show_img]631-jco-img-5.jpg[/show_img]JCO This is a first stage arch with a tipback in the molars?
DR. WAGERS Yes.
JCO And not tied into the deciduous second molars?
DR. WAGERS Right. We use retaining rings, which allow complete freedom of movement of the archwire. We rarely seat the archwire in the brackets of the deciduous molars in the first phase of treatment.
At the end of the first phase, in this case, the lower incisors moved back ½mm behind the APo line from 4mm to 4½mm, and the maxillary incisors were moved back end-to-end to the lower incisors.
[show_img]631-jco-img-6.jpg[/show_img]There was little molar change; a loss of molar anchorage of only one millimeter. The molars were moved to Class I, but in a critical anchorage case, such as this, we don't want to move the molars any more than we have to in the first phase. We did want to open the bite and move the incisors back to an end-to-end position. Then, we leave them out of control to assume their natural balanced position with the lips and tongue.
This bite had not opened as much as usual, and the molars had not elongated. Mandibular plane, which we measure as Go-Gn-SN, remained the same. So, all that really happened was the retraction of the maxillary anteriors. Most of the time, we get an increase in ANB, at this stage, with an elongation of the molars and a downward and backward rotation of the mandible. This generally recovers, in the rest period. If you get chin growth, ANB decreases. After that, it doesn't change much in the second period of treatment.
At the beginning of the second period, ANB difference was 5°, but at the end of treatment it was back at 3°.
[show_img]631-jco-img-8.jpg[/show_img]The mandibular plane angle did change 3°, in the second period. We were able to move the lower incisor from -4mm to 0, to the APo line. There was a slight tendency for a lateral open bite, but otherwise, the case has remained stable.
To further illustrate banding in first phase correction, consider the next patient, an 8-year-old (C.M.) with a protrusion and a tooth size to arch size discrepancy, for whom we removed deciduous cuspids, deciduous first molars and the first bicuspids, before their eruption.
[show_img]631-jco-img-9.jpg[/show_img]The mandibular incisors are on the APo line. The maxillary incisors are 10mm ahead of the APo line. There is a tooth to arch size discrepancy. There is not enough room to retract the incisors without overcrowding the remaining teeth. This is why we removed first bicuspids prematurely in this case. At the end of the first phase of treatment, the lower incisors were 3mm behind the APo line and the ANB difference decreased 1mm. The bite had not opened much and point A moved back a bit. The mandibular plane angle remained the same . We put little stress on the anchorage as very little was lost.
[show_img]631-jco-img-10.jpg[/show_img]In this case, we didn't use loops, and used very light forces -- 1½ ounces -- which is about all that is necessary. Note the stops distal to the laterals to keep the incisors from drifting apart.
After 3 months of treatment the Stage I wires are loosely tied in, using retaining rings on the first deciduous molars. We suspended treatment and placed retainers after 6 additional months, for a total of 9 months first period treatment. The incisors should be end-to-end at this point, but remember this case was an open bite problem and we are not concerned about it closing a little.
This is typically what a case looks like at the end of Phase I. The anteriors have been moved back as far as they should go and are still able to move back properly to the APo line.
[show_img]631-jco-img-11.jpg[/show_img]This case continued closing in the waiting period. This was not surprising, because early removal of first bicuspids in serial extraction or in preorthodontic guidance will invariably result in bite closure due to a dropping back of the mandibular incisors. In this case, at the beginning of the second phase of treatment the mandibular incisors were 2mm behind the APo line and the bite was closed. In the rest period, there will be more bite closure in low angle cases, than in high angle cases. At the end of the second phase of treatment, lower incisors were moved to only 1mm behind the APo line. The bite closure was corrected.
During retention and at dismissal, the incisors moved back to - 3mm to the APo line. Some of this was due to chin growth, but facial appearance was good in the final records.
[show_img]631-jco-img-12.jpg[/show_img]JCO How do you decide at this age that you have a discrepancy that is great enough to require the extraction of the first bicuspids?
DR. WAGERS We measure tooth size and available arch length, from the six-year molars forward, both on the x-rays and in the mouth or on the casts. By measuring the teeth that are already in place and the same teeth on x-ray, we determine if there is any x-ray distortion to account for, and make a judgment based on the amount of available arch space compared to the amount of tooth structure.
JCO If you were able to anticipate that chin growth, would you still remove teeth?
DR. WAGERS Yes. I would not treat this case nonextraction, if I had it to do over again. The occlusion will be more stable by extraction treatment. Many of these cases, that have excessive chin growth in the so-called "button" area, also have a very tense lower lip. This seems to go together. The more the chin grows, the more the lip drops back and crowds the teeth. It is hard to reach a balance. In this case, if we had left all the teeth, we would have had a more prominent upper lip and not as pleasing a face.
She is a pleasant looking girl and I am not unhappy with the result, in spite of the fact that her incisors are behind the APo line. Of course, the ballpark goal is ±3mm to the APo line, but moving incisors nearer to the APo line is considered to be more stable.
JCO Is the temporary retainer worn all the time between Phase 1 and Phase 2? DR WAGERS Yes, we have patients wear the temporary retainers all the time, except when they eat. I don't know whether full time wear is necessary. We have better luck with retainer wear if it is full time. Patients seldom have problems with retainers and seldom lose them during full time wearing. One of the advantages of mixed dentition treatment is that young children are more receptive and follow instructions better than teenagers. Another advantage of mixed dentition treatment is that the 2nd phase treatment in the permanent dentition stage will be 9 months shorter than waiting and starting in the permanent dentition treatment for only one phase. The two periods of treatment together average the same amount of treatment time as permanent dentition treatment will later. First phase treatment averages 9 months and is finished before eruption of all permanent teeth.
JCO Let's discuss how you handle the finances for two-phase treatment.
DR. WAGERS This is important. Parents of children with severe protrusion cases, anxious to start treatment, are made to understand that there are two definite phases of treatment. There is an initial fee and monthly installments in both periods. In the 2nd phase there is a smaller initial fee, which we call a continuation fee. It is about one-half of the first period initial fee. We explain to the parents that two-phase treatment will add some to treatment cost, because there will be office calls during the rest period and the continuation fee. This is all written down and we honor this 2nd period treatment fee, even though there might be a 3-4 year rest period. In times of great inflation, this is a mistake. We should adjust the fee according to the percentage of inflation. We are now, for example, honoring some monthly treatment fees that are lower than our present regular monthly fees, because the patients were started in first phase treatment several years back. The majority of cases will not have a rest period over two years, but some can exceed 36 months. If rest periods exceed one year, we now tell parents that we may have to adjust monthly fees to inflation and charge our current monthly fees. If there is one thing I have learned about being comfortable in practice, it is to explain and write down at the beginning what the problem is and the fees for service. We explain it two or three times, write it out and give it to the parents in writing. We keep a copy. You will never have a better time to explain all ramifications than at the beginning. We have never delegated parent and patient consultations to auxiliary personnel because of the importance of that first contact with patients and parents. For future practice comfort you must let them know what is going to happen. Auxiliary personnel can be better utilized in many other ways.
The next case (M.C.) is an open bite, bimaxillary dental protrusion.
[show_img]631-jco-img-13.jpg[/show_img]Mandibular incisors were 2.5mm ahead of the APo line; maxillary incisors were 12mm ahead of the APo line.
[show_img]631-jco-img-14.jpg[/show_img]In preorthodontic guidance, we removed the deciduous incisors and deciduous first molars and the remaining teeth erupted into place very well. The cuspids moved back much more than the posterior teeth drifted forward.
The cuspids had become prominent on palpation since there was a severe protrusion and an openbite. We decided we must go into treatment as early as possible. So, we removed the first bicuspids prematurely. We rarely remove first bicuspids before all the incisors have erupted. This was a preorthodontic guidance procedure prior to mixed dentition treatment. Usually, we do not treat Class I bimaxillary protrusions in the mixed dentition, unless the protrusion is so severe that it prevents closure of the lips. Bimaxillary protrusion, unless unusually severe, is not generally an indication for mixed dentition treatment.
JCO How about Class II bimaxillary protrusion?
DR. WAGERS Yes, if the protrusion is severe. In this case, it took just 4 months to move the incisors back to an end-to-end position. The maxillary incisors were 12mm ahead of the APo line and we moved them back to 1.5mm ahead of the APo line or 10½mm retraction.
[show_img]631-jco-img-15.jpg[/show_img]Lower incisors to APo was originally 2.5mm. We moved these teeth back 5.5mm. We used Class II elastics for about two months, and then went to intramaxillary elastics and Class II elastics (Stage II elastics) for the last two months in order to
move the incisors back.
[show_img]631-jco-img-16.jpg[/show_img]During a 2½-year rest period, the patient wore an upper temporary retainer which was stopped about 4 months prior to starting the second phase of treatment. This was done to see if the protrusion would reoccur.
[show_img]631-jco-img-17.jpg[/show_img]At the start of Phase 2 we banded all the teeth, except the second molars. We do band second molars on occasion, but generally we band them toward the end of treatment. Second phase treatment lasted exactly 12 months and total banded time was 16 months. Stage III took only about 4 months. This case did not need a lot of uprighting. These are the final records made at dismissal, after the removal of third molars.
[show_img]631-jco-img-18.jpg[/show_img]We remove third molars after treatment in all cases where third molars are likely to become impacted.
JCO Do you think you see less lower anterior relapse, because you routinely take the third molars out?
DR. WAGERS Yes, I do. Clinically, we don't have as much lower anterior relapse as in former years. If the third molar is crowded for arch space and mesially inclined, it will erupt toward second molars and if it doesn't move them, it must become impacted.
JCO You had a nice facial result on this case.
DR. WAGERS My clinical observation is that facial results are better in 2-phase mixed dentition cases than those treated in the permanent dentition only. Early correction of protrusions allows facial growth on a better foundation and there seems to be less facial imbalance. In-depth research should be attempted in view of this clinical observation.
[show_img]631-jco-img-20.jpg[/show_img]The next case (T.L.) was a severe protrusion with a severe discrepancy.
We removed the deciduous cuspids, deciduous first molars, and the permanent first bicuspids immediately before starting two-phase treatment.
[show_img]631-jco-img-21.jpg[/show_img]At the end of the first phase the ANB shows a decrease, which is not usual.
[show_img]631-jco-img-22.jpg[/show_img]The lower incisors only moved back 2mm and are still ahead of the APo line. We did move the maxillary incisors back to -1mm to APo.
The first phase of treatment lasted 9 months. We waited 2 years, 5 months during the rest period for the remaining teeth to erupt. There was some return of the protrusion and bite closure. The ANB difference increased a couple of degrees. The lower incisors stayed about where they were at the end of first phase treatment. By the time the second phase treatment finished, they moved forward another millimeter. The ANB changed little and, basically, we opened the bite and moved the anterior teeth back slightly.
[show_img]631-jco-img-23.jpg[/show_img]Posttreatment growth of the mandible was in a counterclockwise direction as recorded in enucleation cases by Ingram in the July 1976 Angle Orthodontist. The mandibular plane angle decreased after retention.