03 - The Best Time for Orthodontic Treatment

Background

Treatment Timing Controversy: How Early?

A debate within the dental profession on the timing of orthodontic treatment went public in the early 2000s, as several major newspapers ran lengthy stories about whether early (preadolescent) orthodontic treatment really benefited patients.Excerpts of those stories appeared in papers all over the country, and almost all dentists were asked about it. Sporadic news reports on that subject continue because there still is controversy within the dental profession. As with any controversy, some see it one way, some another.

It doesn’t matter whether you’re a specialist in that aspect of dentistry or not; whenever a controversy about the best way to treat some type of dental problem comes up, you’re going to get asked about it if you’re in dental practice. You don’t have to know the details of exactly how to treat the problem, but you have to know enough about it to give an intelligent opinion. That’s especially true when it’s a child from your practice who receives contradictory opinions from different specialists. Nothing gets a mother’s attention like the treatment that is planned for her child.

What do you say to a parent with questions about the best time for her child to have orthodontic treatment? Even closer to home, when should your child start orthodontic treatment?

Even prior to starting school? — primary dentition

Preadolescent, elementary school years? — early mixed dentition

Adolescent, junior high/high school years? — late mixed/early permanent

Even later, for best results? — late permanent dentition

Story introduction	Minor miracles
Critical view	Sooner than later?

Effectiveness and Efficiency in Treatment

There are two important things to consider in the timing decision:

Effectiveness: How well does the treatment work? To what extent does it solve the patient’s problems? The more improvement it produces, and the more ideal the result, the more effective it is. Is effectiveness different at different stages of growth?

Efficiency: How much effort does it take to achieve a satisfactory result? How does the benefit of treatment relate to risk and cost? For equivalent results, the more it costs, the less efficient it is. Is efficiency different different at different stages of growth?

Remember that there are two kinds of costs when efficiency is evaluated:

1. The economic cost, in dollars, which reflects the amount of time and effort for the doctor and staff.
2. The burden of treatment, which is its impact on the patient and the parent. The greater the risk associated with the treatment, the more the child experiences discomfort and complains to the mother, the more appointments that have to be kept even if they interfere with school or soccer practice, the greater the inconvenience of travel, a whole series of things like that: the greater the burden of treatment.

The best treatment has the best combination of effectiveness and efficiency.

Obviously, the best time for treatment would be when it is most effective and most efficient. Timing is important when the patient’s growth will affect the treatment outcome, as it almost will in orthodontic treatment for children and adolescents.

Principles That Affect Treatment Timing

Some important principles affect the timing of treatment:

1. Growth modification often is desirable.

For example, in a growing patient with a skeletal Class II jaw relationship, guiding growth so that the mandible grows forward more than the maxilla is the best way to solve the problem.

One approach is to use a fixed functional (Herbst) appliance, illustrated here. The appliance holds the mandible forward, which tends to accelerate its growth, and the reaction creates some restraint of growth of the upper jaw. There are a number of alternative approaches in Class II growth modification, but the goal is the same: differential forward growth of the mandible.

Treatment of this type

• is most effective during the adolescent growth spurt
• should be completed about the time the growth spurt ends, otherwise much of the effect can be lost to rebound growth

If you start too late, it doesn’t work—you can’t modify growth that isn’t happening, and the treatment would not be effective.

If you start too soon, it takes too long—you can’t quit until the growth spurt ends. So even if the treatment were effective, it would not be efficient. Both the burden of treatment and the economic cost would be unnecessarily high.

Dental vs. Skeletal Maturation

Some important principles affect the timing of treatment:

2. Tooth eruption correlates—but not too well—with the skeletal growth status and the timing of the adolescent growth spurt.

This graph shows the variation in adolescent growth for American girls with early, midrange, and late maturation, and the variation in timing of eruption of the mandibular canines and premolars. Because tooth eruption correlates with skeletal growth, early maturing girls are likely to also have early eruption of their teeth.

But because the correlation is not as high as you might think, tooth eruption can and does occur over a wide range of physical development. Some children (especially girls) have almost completed their growth before they lose the last baby teeth. Others (especially boys) have all their permanent teeth almost before their growth spurt starts.

So the dentist has to judge physical maturation, not just the stage of dental development, to decide when treatment should start.

What does that mean?

• For skeletal problems (Class II/III), choose when to send a child for orthodontic treatment by the physical maturation level, not the dentition.
• If the problem is only dental (Class I crowding), judge by the dentition.

Position of Primary vs. Permanent Teeth

3. Permanent teeth often do not erupt where their primary predecessors were.

The patient shown here had early expansion of the maxillary arch to make space for the teeth. Note that the canines and premolars aren’t erupting into ideal arch form, although the primary canines and primary molars were in the ideal position after the early treatment. To obtain good occlusion, further treatment to align these teeth will be needed.

The result: If early (mixed dentition) treatment was done, a second phase of treatment after the permanent teeth erupt usually is necessary to obtain normal occlusion.

Adolescent Treatment: The “Gold Standard”

Based on those principles, we can conclude that the best time to treat most orthodontic problems is during the adolescent growth spurt.

Why? Because for most patients this gives the best combination of effectiveness and efficiency.

• The permanent teeth are available for final alignment.
• Effective growth modification can be obtained if needed.
• The treatment ends as adolescent growth slows to the low rate of later life (growth doesn’t totally stop—adults continue to grow, very slowly).
• One stage of treatment, rather than a first phase during the mixed dentition and a second phase later, gives a shorter treatment time and maximum efficiency.

Why Deviate from the Gold Standard?

Why would you deviate from the gold standard, treating earlier or later?

Obviously, because treatment at a different time would be more effective, more efficient, or perhaps both.

Let’s start by asking when it might be wise to delay treatment beyond the adolescent growth spurt. Why would you do that?

Primarily if prolonged growth (after the adolescent growth spurt) would cause relapse after treatment at the usually optimal time.

Indications for Later Treatment

The major indication for delaying treatment until after adolescence:

• Class III due to excessive mandibular growth.

Class III patients with excessive mandibular growth differ from the norm in two ways: Their mandibles are large, and their mandibular growth doesn’t stop at the end of the adolescent growth spurt.

Continued mandibular growth in this girl between age 16 and 19 is obvious from examining her profile. Sometimes these patients look reasonably normal until they just don’t stop growing at puberty. There is no good way to stop excessive mandibular growth—attempts to modify growth in that way, including early orthognathic surgery, just doesn’t work reliably—so the best plan is to wait until growth stops, then treat it. For this girl, that meant delaying treatment until she finally stopped growing at age 19.

Severe long face problems also may have to be treated after adolescence, because often vertical growth in these patients doesn’t stop when it should. But growth modification aimed at restricting downward growth of the maxilla and controlling eruption of posterior teeth can help some long face patients and is worth trying during adolescence.

Indications for Earlier (Preadolescent) Treatment

Whether to start treatment before adolescence and if so, when, are the controversial issues at present.

What would be the indications for early treatment? It should be either

• More effective: produces a result that could not have been obtained with later treatment, or
• More efficient: produces as good a result with less cost/burden of treatment.

Let’s look at treatment timing for the major types of malocclusion from this perspective, starting with Class I crowding/protrusion.

Class I Problems

Background Concept

For treatment of Class I crowding/protrusion problems, first, an important concept:

• There’s no need to modify growth in patients who have a normal jaw relationship. So for these patients, the stage of dental development rather than skeletal maturation is more important.
• But erupting teeth often become a demonstration of the “law of the perversity of inanimate objects,” erupting in poor positions even though they had every opportunity to erupt in the correct place. That’s why a second stage of treatment in the early permanent dentition usually is necessary after mixed dentition treatment of Class I patients.

It is extremely unlikely that two phases of treatment would be more efficient than one. Only if early treatment eliminated or significantly shortened the later second phase could it be more efficient.

The reason for early treatment for crowding and/or protrusion, therefore, would have to be that it produced a better result, and thus was more effective.

There are two approaches to crowding/protrusion (which are discussed in detail in the program To Extract Or Not To Extract, Part 1. These are expansion of the arches or extraction of some permanent tooth or teeth, usually first premolars.

Let’s look at the timing of expansion first.

Class I Crowding/Protrusion: Early Expansion?

Keep the definition in mind: Early treatment is done in the mixed dentition, prior to the adolescent growth spurt, before the canines and premolars erupt. There is no doubt that early expansion is effective—it works. The question is whether it works better than later expansion that does not require such prolonged treatment time.

Early expansion often is done with a jackscrew device, which widens the upper arch by opening the midpalatal suture. If treatment started in the primary dentition (image 1), it would still have to continue through adolescence, so expansion in the primary dentition almost never is a good idea. If it were done in the primary dentition, light force is sufficient. A jackscrew device like the one shown in image 1 is unnecessary and should not be used in a young child. This child suffered an injury because of excessive force from the screw device.

In the mixed dentition (image 2), the expander often is bonded to the primary and permanent molars, as shown in the lower image. By this age, a jackscrew device is acceptable if it is not activated too rapidly. It’s generally accepted that this is appropriate treatment for a child with a posterior crossbite due to a narrow maxilla.

What if the child has crowded teeth but no crossbite? Then the maxillary expansion would produce a buccal crossbite. It has been claimed, but not demonstrated, that this makes it possible to expand the lower arch more than would have been possible with a fixed appliance later (image 3). No evidence exists to verify this claim.

The bottom line: Compared to later expansion during adolescence, early expansion is

• probably no more effective
• certainly less efficient

Image 1, primary dentition: A jackscrew device for expansion should not be used in the primary dentition.	Image 2, early mixed dentition: A bonded expander with a jackscrew is appropriate in the mixed dentition if the maxilla is narrow.
Image 3, early permanent dentition: Fixed appliance with bonded brackets for expansion in the early permanent dentition.

Class I Crowding/Protrusion: Early (Serial) Extraction

The other possibility for treating crowding/protrusion, of course, is extraction.

Early extraction (usually referred to as serial extraction) was used widely in the mid-20th century in the hopes that it would simplify or even eliminate the need for later treatment. The objective was to systematically move the crowding in each quadrant of the dental arches around to the point where a permanent tooth—almost always the first premolar—would be extracted.

Typical serial extraction has three stages:

• Removal of primary canines to provide enough space for the permanent lateral incisors as they erupt (image 1).
• Removal of the primary first molars before they would normally be lost, to encourage eruption of the first premolars (image 2).
• Extraction of the first premolars before the canines and second premolars erupt (image 3). Usually the second primary molars also are extracted at this point.

This allows the canines and second premolars to share the space of the first premolars as they erupt, and if the potential crowding was severe, the space would be totally closed (image 4). In an ideal world, further eruption of the teeth would lead to proper positioning of the roots and excellent occlusion (image 5). Since this is not an ideal world, often the final result is not so good.

Image 1, 1st stage, serial extraction: 1st step, serial extraction: extract primary canines.	Image 2, 2nd stage: 2nd step: extract primary 1st molars when 1st premolars are nearly through the alveolar bone.
Image 3, 3rd stage: 3rd step: extract permanent 1st premolars before canines/2nd premolars erupt.	Image 4, 4th stage: Eruption of canines/2nd premolars into 1st premolar space.
Image 5, completion: Closure of residual space, root paralleling (which usually requires a period of fixed appliance treatment).

Problems with Serial Extraction

There are two problems with serial extraction:

1. It requires accurate prediction that the crowding is severe and that extraction really will be necessary for an individual patient. Since extraction is irreversible, even if the probability of an error is small, a mistake is a serious problem.

2. A second phase of treatment is needed after the permanent teeth erupt. A typical serial extraction result, in a child who did have so much crowding (10 mm space discrepancy in each arch) that extraction was necessary, is shown here in the accompanying images. The typical findings are:

• alignment is improved but not perfect
• some extraction space remains
• excessive overbite has developed

For this reason, a second stage of fixed appliance treatment almost always is needed. The deepening of the bite can be difficult to correct, but the length of the fixed appliance treatment is less than it would have been with late extraction.

Image 1, frontal view: Serial extraction result: note anterior deep bite (excessive overbite).	Image 2, right lateral: Right lateral view: overbite, imperfect alignment.
Image 3, left lateral: Left lateral view: overbite, good alignment.	Image 4, upper occlusal: Upper occlusal: rotations, extraction space not totally closed.
Image 5, lower occlusal: Lower occlusal: small space on left, mild incisor crowding.

Serial Extraction: The Bottom Line

Serial extraction is not a cheap way to avoid orthodontic appliance therapy for most children. It was hoped at one time that properly timed extractions would make conventional orthodontic treatment unnecessary for most children with crowding/protrusion. It now is well documented that this is not the case.

On the other hand, because it does have the potential to reduce phase 2 treatment time, it isn’t necessarily less efficient than later one-phase treatment. A similar number of total visits can be spread over a longer period of time if phase 2 is shortened sufficiently.

What about the effectiveness of serial extraction? If a child really is severely crowded, serial extraction has advantages that can lead to a better result than later extraction. It

• eliminates incisor crowding during the mixed dentition, which can make both the parent and child happier during that period.
• reduces phase 2 treatment time.
• may also reduce the chance that crowded-out canines will erupt through mucosa instead of gingiva, thus improving long-term periodontal health.
• may also improve long-term stability. It seems reasonable that if the incisors were never allowed to become malaligned, they should be more stable in the long term, but the evidence for this is questionable.

Modern guidelines restricts serial extraction to children with

• 10 mm or more crowding in both arches predicted by space analysis
• normal facial proportions (not skeletal Class II/III, short/long face)
• phase 2 treatment definitely available

Most children with crowding/protrusion are excluded by those restrictions. For the small group who are candidates for it, serial extraction can be judged to be both effective and reasonably efficient.

Timing Guidelines, Class I Crowding/Protrusion

So how do we summarize the timing guidelines for Class I patients?

• Unless crowding is very severe as the lateral incisors are erupting and the serial extraction criteria exist, don’t extract mandibular primary canines prematurely. No treatment is needed at that point, unless extraction of maxillary primary canines is needed to decrease the chance of canine impaction.

It takes a lot more potential crowding than is seen in image 1 to justify the extraction of primary canines to make space for lateral incisors.

• If one or both primary canines are lost spontaneously as the lateral incisors erupt, some early treatment is indicated: Keep it symmetric: extract the other primary canine if only one was lost. Use a lingual arch to maintain space unless the strict criteria for serial extraction are met.

One of the patients shown in image 2 needs extraction of the other mandibular primary canine and both need a lingual arch to maintain space—but neither needs anything else now. This keeps the option open for long-term expansion or extraction and prevents the development of major asymmetry in dental arch.

• Arrange for orthodontic treatment to begin just before the second primary molars are lost, so that leeway space (the difference between the size of 2nd primary molars and 2nd premolars) can be used to help resolve any space discrepancy.

The patient in image 3 is close to the ideal time to start fixed appliance treatment for mild/moderate crowding. If crowding had been more severe, placing an appliance on the lower arch before leeway space was lost would have been indicated.

Image 1, no serial extraction: Moderate crowding, not enough to indicate early treatment.	Image 2, lingual arch needed: More severe crowding: maintain space and symmetry.
Image 3, gold standard time: Ideal treatment time: just as 2nd primary molars are ready to exfoliate.

Class II Problems

Background Concept, Growth Modification

Important concepts in treatment of skeletal (jaw relationship) problems:

• The major reason for early treatment is to modify growth. Tooth movement (as for camouflage of a skeletal problem) can and should be done later.
• Growth modification at an early age tends to wear off as uncontrolled later growth occurs, so what looked successful in the short term may not be so successful in the long term.

Dentists’ opinions about the effectiveness of early Class II treatment have changed back and forth over time. Recently, many have been enthusiastic about early (preadolescent) treatment, on the theory that growth modification would be more successful at that time. Others have doubted that two phases of treatment would produce a better outcome than later one-phase treatment.

By far the best way to evaluate alternative treatment approaches is a randomized clinical trial. For early (preadolescent) vs later (adolescent) Class II treatment, clinical trial data became available in the late 1990s. The National Institute of Dental and Craniofacial Research funded a 10-year study at UNC that allowed a careful comparison of the outcomes in children who did and did not have early treatment for comparable problems (image 1). Two other major clinical trials were carried out at the University of Florida and at Manchester University in England, and several smaller trials were done elsewhere. Let’s look at the results, focusing first on the UNC trial and then broadening the overview.

Class II Clinical Trial: Research Design

The UNC clinical trial, like the other major trials, was designed to answer two major questions:

• Did preadolescent treatment really modify growth?
• Was there any difference in the final outcome between children who had early (preadolescent) treatment followed by a second phase of treatment at adolescence, and those who had only one phase at adolescence?

In the trial, preadolescent Class II children were randomly assigned to one of three groups:

• No treatment until adolescence
• Headgear treatment
• Functional appliance treatment

All the children in each group, including the untreated controls, had progress records taken after 15 months in phase 1. If needed, phase 1 treatment continued, and at the appropriate time later, during adolescence, all the children received comprehensive fixed appliance treatment.

Class II Clinical Trial: Phase 1 Outcomes

At the end of the first phase, there was a small but statistically significant difference in jaw growth between the children who had treatment and the untreated controls—so now there is good evidence that early treatment is effective.

But the variability in results was perhaps the most impressive finding. This graph shows the percentage of patients whose jaw relationship improved greatly, improved somewhat, stayed the same or got worse with or without treatment. The ANB angle, of course, is one measure of the difference between the position of the maxilla and mandible. If it decreases, the jaw relationship is improving. A highly favorable response would be a large decrease, unfavorable would be an increase.

Note that a few of the untreated children improved, most showed no change, and some got worse. In the treated groups, some improved impressively, the majority improved a little, and 25% showed no response or got worse. Cooperation obviously was a factor in treatment response, but it did not explain all the variability.

With this variability, if you were an advocate of a particular approach, it would be easy to select the right children to illustrate that your point of view was correct. Many published case reports, in fact, demonstrate different outcomes in different children from similar treatment procedures. Clinical impressions obviously can be misleading.

The conclusion from the first phase of the trial: Although early treatment is effective in general, it does not improve the jaw relationship every time. Things change for some children in both directions, in the absence of treatment.

Class II Clinical Trial: Phase 2 Outcomes

The first phase of treatment was effective—it produced the desired change in most (but not all) patients.

That brings us to the second major question:

• Did early treatment produce a better (different) outcome at the end of phase 2, after both the treated children and untreated controls had fixed appliance treatment during adolescence?

The factors that would need to be considered would include

• dental occlusion
• jaw relationship
• type of treatment needed in phase 2 nonextraction orthodontics extraction orthodontics orthognathic surgery
• treatment time

Let’s look at these one at the time, using the phase 2 data.

Clinical Trial Phase 2: PAR Scores

Perhaps the best way to measure the quality of the dental occlusion is to use PAR scores. These scores are derived from a weighted system (in which overjet is emphasized) to evaluate

• Overjet, overbite, midlines
• Alignment of maxillary and mandibular teeth
• Right and left buccal occlusion

PAR scores are like golf—low score wins. A PAR score of 5 or lower is nearly perfect occlusion, under 10 is good. A patient with a typical Class II malocclusion would have a score in the 25-40 range before treatment.

Data for changes in mean PAR scores for the three groups of patients are shown in image 1, and the percentages of children with excellent, good and disappointing scores at the end of phase 2 are shown in image 2.

The objective of phase 1 treatment was growth modification, not improvement in the occlusion, so it is not surprising that PAR scores changed very little in phase 1 (image 1). Phase 2 treatment greatly reduced the mean PAR scores for each treatment group, and at the end of Phase 2 there was no difference in the mean scores for those who did and did not have a first phase of early treatment. The distribution of children by phase 2 PAR scores also was the same for the three groups.

The bottom line: Early treatment didn’t make any difference in the extent to which the Class II malocclusion was corrected.

Image 1, mean PAR scores: Changes in PAR scores during phase 2, without/with early treatment.	Image 2, PAR score distribution: The distribution of children with excellent/good/disappointing PAR scores after phase 2 treatment, without/with early treatment.

Clinical Trial Phase 2: Jaw Relationships

The goal of phase 1 treatment was to improve jaw relationships, and on average, it did. What happened to jaw relationships during phase 2? In this table (image 1), look at the amount of decrease in ANB for the three groups during early (phase 1) treatment, during phase 2, and the total for both phases.

The interesting result: The difference between the previously treated and untreated control children nearly disappeared during phase 2. The ANB angle decreased more for the previous controls during phase 2, and they almost caught up with the children who had early treatment, even though phase 2 treatment did not focus on the jaw relationship. The same effect is observed when other indicators of jaw relationship are measured.

The bottom line: Early treatment made very little long-term difference in jaw relationships. At the end of phase 2, the differences between the children who had two phases of treatment and those who had only one were no longer statistically significant.

Clinical Trial Phase 2: Extraction Percentage

One of the possible advantages of early treatment would be a reduction in the number of patients who would need premolar extraction during phase 2 (for camouflage—see To Extract Or Not To Extract, Part 2). It seems reasonable that if growth modification were successful during phase 1, the extraction percentage should be lower in children who had early treatment.

In phase 2 treatment, the orthodontist was instructed to do whatever it took to produce the best outcome for that individual patient—so extractions were used if they were needed, in the doctor’s opinion. The data show differences among doctors, as would be expected.

But as the chart shows, for the three groups of patients who did or did not have early treatment, the differences in the number of patients with extractions during phase 2 were small and not statistically significant. It often has been claimed that early functional appliance treatment decreased the need for later extractions. The data clearly did not support that contention.

Clinical Trial Phase 2: Orthognathic Surgery Percentage

It also seems reasonable that taking advantage of growth at an early age might reduce the number of patients with severe Class II problems who ultimately would need orthognathic surgery. All patients enrolled in the clinical trial had to have at least a moderately severe Class II malocclusion, but there was no upper limit on severity, so some of the children had quite severe problems. It would be expected that some of them eventually would require orthognathic surgery.

As the chart shows, if early treatment decreased the chance that orthognathic surgery ultimately would be needed, the change was small. The small difference between early and later treatment is suggestive but not statistically significant.

The bottom line: The results for orthognathic surgery were the same as for other indicators of effectiveness. The clinical trial data did not support two-phase treatment with a first phase prior to adolescence as being more effective (producing a better result) than one-phase treatment during adolescence.

Clinical Trial Phase 2: Treatment Time

Finally, one would hope that at least some of the time spent on early treatment would be recovered by shorter phase 2 treatment time later.

The clinical trial data, however, show no significant difference in phase 2 treatment time with or without early treatment. As the graph demonstrates, the median treatment time in phase 2 was very similar for the three groups, and the distribution of phase 2 treatment times was nearly identical.

The conclusion: For most patients with Class II problems, a first phase of treatment prior to adolescence is

• No more effective then later treatment
• Considerably less efficient

An important caveat: Children with severe skeletal vertical problems (severe short or long face) were not included in the clinical trial. Its conclusion, therefore, applies to children with a skeletal Class II malocclusion and reasonably normal face height.

Class II Treatment Timing: Summary/Recommendations

The data for the clinical trials of preadolescent vs. adolescent treatment of children with skeletal Class II problems have been reviewed by an expert group, using the criteria of the Cochrane Collaboration that evaluate the quality of the research. The bottom line: “For most Class II children, there is no advantage in beginning treatment before the adolescent growth spurt.”

Does that mean early treatment is never indicated for a Class II patient?

No—but it does mean there should be a good reason for early treatment and that early treatment is not indicated for the majority of Class II children.

Remember, treatment timing is related to skeletal development, not dental development, so a rapidly maturing girl who still is in the mixed dentition as she enters her adolescent growth spurt should start treatment (for her, it’s not really early), and a slowly maturing boy whose teeth have erupted probably should wait for the growth spurt (for him, it’s still early).

What characteristics should lead you to recommend orthodontic consultation for a preadolescent Class II patient in your practice? The current guidelines, based on an interpretation of the clinical trial results:

• Evidence of major social problems from teasing, etc. Problem severity should be determined by its effect on the patient’s quality of life, not characteristics like mandibular deficiency or overjet.

• Evidence of damage to teeth or soft tissues that is related to the malocclusion.

Since data from a randomized clinical trial involving children with combined vertical and anteroposterior problems are not yet available, it is possible that early treatment might be advantageous for children with a short-face or long-face Class II problem. On that point, clinical opinions still are the best available information.

How many Class II children meet these guidelines for early treatment? Except that it obviously isn’t the majority, we still don’t know with any precision.

Class III Problems

Background Concepts

Class III problems can arise from maxillary deficiency, mandibular excess, or their combination. Important background concepts:

• Excessive mandibular growth is almost impossible to control. Devices that put force against the chin to restrain the mandible (like the chin cup shown in image 1) are not effective in most circumstances, probably because children will not tolerate the amount of force and time required.
• In contrast, deficient maxillary growth can be stimulated with force to pull the maxilla forward. As we have described previously, there are two ways now to do that: reverse pull headgear or face mask (image 2), or Class III elastics to bone anchors (image 3). But the window of opportunity for non-surgical face mask treatment closes around age 10, so treatment should start at age 8 or 9; therefore, referral for early treatment is critically important. Treatment with bone anchors is possible in the early part of the adolescent growth spurt but also should start as early as possible (when there is enough bone maturation to hold the bone screws), ideally at age 10 1/2 or 11.

Image 1, chin cup: Devices to place force against the chin do not succeed in restraining mandibular growth.	Image 2, face mask: Devices to pull the maxilla forward to reduce skeletal maxillary deficiency can succeed—but only if used very early.

Chin Cup to Restrain Mandibular Growth

The image you see here is from a textbook published in 1890. The caption under the picture described the use of this chin cup device to inhibit mandibular growth, then said, “Unfortunately, it doesn’t work very well.” More than 100 years later, that is still the best summary.

There are two problems with chin cups:

• Mandibular growth restraint requires a level of cooperation (and tolerance of pain) that is very difficult to obtain in children.

• Patients with excessive mandibular growth differ from the norm in two ways:Their mandibles grow too much, and as we noted previously, They don’t stop growing at the end of the adolescent growth spurt

• So any restraint or redirection of growth tends to be canceled out by “rebound” growth afterward unless the treatment is continued well into adolescence.

The bottom line: Early treatment with a chin cup is neither effective nor efficient.

Face Mask to Stimulate Maxillary Growth

Until the 1970s, it was thought to be impossible to stimulate forward growth of the maxilla. Then it was discovered that if force to bring the maxilla forward is employed at quite young ages, it is possible to obtain skeletal change. The original guideline, from the French surgeon who pioneered this method, was that the treatment had to be done before age 8 to be effective.

The treatment is done with a face mask (reverse pull headgear) (image 1), placing relatively heavy force against the maxillary teeth that is transmitted to the maxilla. Skeletal change, not tooth movement, is the goal. The teeth must be splinted to minimize tooth movement. Treatment can start in the primary dentition, but to control tooth movement, it helps to have the maxillary first molars available, so age 7 is the preferred time.

This boy wore his face mask for 12 hours per day for a year, between ages 7 and 8. The improvement in the prominence of his maxilla is apparent (image 2).

The upper age limit for success with face mask treatment has moved up a little recently, but it remains clear that if a face mask is used when a patient is approaching adolescence, the only effects are tooth movement and downward/backward rotation of the mandible, not forward growth of the maxilla.

Bottom line: If face mask treatment is going to help a maxillary deficient Class III child, it must start early, preferably before age 8.

Image 1, face mask: Reverse pull headgear (face mask), to provide force against the maxilla to bring it forward.	Image 2, profile change: Profile effect of 12 months of face mask treatment.

Face Mask to Stimulate Maxillary Growth (cont.)

Does that mean all Class III children should have face mask treatment early?

No, only those whose problem is largely due to maxillary deficiency and who would prefer face mask treatment to bone plates that would require (relatively minor) surgery to place them. The moment of truth for the former face mask patients is the adolescent growth spurt. If excessive mandibular growth occurs then, the Class III problem will recur, no matter how much it was improved earlier.

The only solution for excessive mandibular growth is orthognathic surgery, and the best estimate (based on similar results from three studies of long-term outcomes) is that 20-25% of children who responded well initially to face mask treatment will eventually need surgery.

You saw the impressive improvement for this boy with early face mask treatment (image 1). But at age 16 (image 2) he was on the borderline for surgery and mandibular growht was continuing. At age 19 (image 3), he was concerned about his reverse overjet and jaw asymmetry, and was told that orthognathic surgery was the only way to correct it. His problem was a combination of maxillary deficiency, which was significantly improved, and excessive mandibular growth that led to a need for surgery in spite of the favorable face mask response.

Image 1, after face mask: Age 9, one year after face mask therapy was discontinued.	Image 2, 7 years later: Age 16, recurrence of the skeletal Class III problem.
Image 3, comparison: Change from age 9 to 16, with continued mandibular growth.

Class III Elastics to Skeletal Anchorage

As you have seen in earlier modules on temporary anchorage devices (TADs), growth modification is one of the possible uses for skeletal anchors. The technique is built around the use of bone plates in the maxilla at the base of the zygomatic arches that are held by 3 screws, and bone plates mesial and inferior to the mandibular canines that are held by 2 screws (see Level III, . Recent data show that on average, about twice as much maxillary advancement is obtained as with a face mask, even if the force from the face mask is applied to bone screws in the anterior maxilla.

The patient shown in image 1 was treated with this approach, with a treatment duration of 12 months and a gratifying short-term outcome (image 2). What’s the best time to do this type of treatment? The answer still is, as early as possible, which turns out age 10 1/2 to 11, significantly later than the age for face mask treatment. By the time a child’s jaws have matured to the point that bone screws are reliably retained, he or she is already too old to expect a good face mask response—which means that there is a way now to modify Class III growth in children who have entered adolescence.

At what age is a patient too old to expect a favorable response to this type of treatment? It appears that significant advancement of the maxilla is less likely after age 12 or 13, depending on the patient’s maturity. Since the response does include a component of restraint of mandibular growth, it is possible that this might, for the first time, be a way to control excessive growth during adolescence—but that has not yet been demonstrated in enough patients to be sure it would work.

Class III Treatment Timing: Summary/Recommendations

So what should you recommend to the parents of the Class III child in your practice?

• The child should have an early orthodontic evaluation including cephalometric radiographs, so that later cephs could be superimposed to determine the pattern of growth and suitability for early growth modification treatment.
• Early referral means age 7 to 8, earlier if possible.
• If the problem is primarily excessive mandibular growth, a chin cup appliance is unlikely to be effective treatment and orthodontic / surgical treatment should be delayed until after the adolescent growth spurt and a decline in mandibular growth to the very slow adult level.
• If the problem is primarily maxillary deficiency, there are two possibilities:for younger children: face mask (reverse pull headgear) to a splint on the maxillary teeth, with treatment starting by age 8. Class III elastics to maxillary and mandibular bone anchors, with treatment starting at age 10 1/2 to 11
• Be sure the parents understand that this is a growth problem and that even if it’s corrected early, it may recur during adolescent growth.

Treatment Timing Conclusions

The best time for most orthodontic treatment is during the adolescent growth spurt, which usually coincides with the transition from the late mixed dentition to the early permanent dentition.

For children with no skeletal component to their malocclusion (Class I problems), treatment timing is based primarily on the dentition. Early treatment (early mixed dentition) is indicated primarily for

• very severe crowding (serial extraction)
• early loss of primary teeth, especially primary canines (maintain space if serial extraction criteria not met)

For children with Class II malocclusion, early (preadolescent) treatment has been shown to be of limited benefit in most cases. It is primarily indicated a child with

• psychologic problems produced by teasing, etc.
• trauma to the soft tissues or teeth during function (usually from deep overbite)

For children with Class III malocclusion, maxillary deficiency can be improved with face mask treatment, but only at very early ages, well before adolescence. Class III elastics to skeletal anchors can bring the maxilla forward in older children, perhaps up to ages 12 or 13. Mandibular excess, in contrast, is almost impossible to control, and so may better be treated late in adolescence.

Any Class III child is a candidate for early diagnostic evaluation to determine the extent to which the problem is maxillary deficiency, and therefore whether early treatment is appropriate.

Self-Test Referral

The self-test section of this program is designed to help you be sure you have understood the material. Do the assigned reading (Contemporary Orthodontics, 5th ed: pages 472-475 and 480-497; 4th ed: pages 497-498 and 502-516). Then take the test, and use it as a guide for further study and review.

Copyright 2013, UNC Dept. of Orthodontics

Self-Test

Question 1

Which of the following are important considerations in determining the effectiveness of orthodontic treatment?

a. PAR score

b. Appearance of teeth

c. Appearance of face

d. Duration of treatment

1. a and b
2. b and c
3. a, b, and c ✓
4. b, c, and d
5. all of the above

Correct

That’s right, both the quality of the dental occlusion (which can be summarized by the PAR score) and the appearance of the teeth and face are important considerations in determining the effectiveness of treatment. No matter how perfect the dental occlusion, it’s not successful treatment if the patient’s dental and facial appearance isn’t esthetically acceptable. Treatment duration relates to efficiency, not effectiveness.

Incorrect

No, that’s wrong. Both the quality of the dental occlusion (which can be summarized by the PAR score) and the appearance of the teeth and face are important considerations in determining the effectiveness. No matter how perfect the dental occlusion, it’s not successful treatment if the patient’s dental and facial appearance isn’t esthetically acceptable. Treatment duration relates to efficiency, not effectiveness.

Question 2

Which of the following are part of the burden of treatment in orthodontics?

a. Posttreatment pain

b. Travel time to the office

c. Comments about having to wear braces

d. Interest on money borrowed to pay for treatment

1. a and b
2. b and c
3. a, b, and c
4. b, c, and d
5. all of the above ✓

Correct

That’s right, all the annoyances, inconveniences, and economic costs of treatment are part of its burden. The noneconomic costs of treatment have to be considered along with the monetary cost when treatment efficiency is evaluated.

Incorrect

No, that’s wrong. All the annoyances, inconveniences, and economic costs of treatment are part of its burden. The noneconomic costs of treatment have to be considered along with the monetary cost when treatment efficiency is evaluated.

Question 3

(A) The best time to stop preadolescent growth modification treatment is when the jaw relationship has been corrected because (B) Continuing treatment beyond that point would make things worse, not better.

1. A true, B true, A and B related
2. A true, B true, A and B not related
3. A true, B false
4. A false, B true
5. A and B false ✓

Correct

That’s right, both these statements are false. No matter when it starts, the best time to stop growth modification treatment is toward the end of adolescent growth, when little growth remains. For a younger patient, unless treatment is continued, growth in the original pattern will wipe out much or all of the improvement.

Incorrect

No, that’s wrong. Both these statements are false. No matter when it starts, the best time to stop growth modification treatment is toward the end of adolescent growth, when little growth remains. For a younger patient, unless treatment is continued, growth in the original pattern will wipe out much or all of the improvement.

Question 4

Which of the following are reasons why the adolescent growth spurt is the preferred time for most orthodontic treatment?

a. Crooked teeth are more apparent after all the permanent teeth erupt.

b. The rate of growth declines sharply after the adolescent spurt.

c. Only one stage of treatment is needed.

d. Adolescents are, in general, more cooperative than younger children.

1. a and b
2. b and c ✓
3. a, b, and c
4. b, c, and d
5. all of the above

Correct

That’s right, adolescent treatment is preferred because the rate of growth declines sharply after the adolescent spurt, which means that further growth will not undo the treatment effect, and only one stage of treatment is needed because the permanent teeth are available after adolescence. Both effects make the treatment most efficient then.

It’s true that crooked teeth are often more apparent after the maxillary canines erupt, but that isn’t a factor in the timing of treatment relative to adolescence. Unfortunately, adolescents often are less cooperative than younger children, so adolescent treatment generally is preferred in spite of this, not because of it.

Incorrect

No, that’s wrong. The correct answer is b and c. Adolescent treatment is preferred because the rate of growth declines sharply after the adolescent spurt, which means that further growth will not undo the treatment effect, and only one stage of treatment is needed because the permanent teeth are available after adolescence. Both effects make the treatment most efficient then.

It’s true that crooked teeth are often more apparent after the maxillary canines erupt, but that isn’t a factor in the timing of treatment relative to adolescence. Unfortunately, adolescents often are less cooperative than younger children, so adolescent treatment generally is preferred in spite of this, not because of it.

Question 5

What is the major reason for delaying orthodontic treatment until after the adolescent growth spurt?

1. Unpredictable growth in a syndromic patient
2. Class II due to a long face condition
3. Class III due to mandibular excess ✓
4. Slowly erupting permanent teeth that aren’t available until later

Correct

That’s right, the major reason for delaying treatment is excessive mandibular growth, because this often continues well beyond the adolescent growth spurt and can cause relapse after adolescent treatment. The other conditions listed in this question might or might not lead to delayed treatment, but they aren’t the major reason for delay.

Incorrect

No, that’s wrong. The major reason for delaying treatment is excessive mandibular growth, because this often continues well beyond the adolescent growth spurt and can cause relapse after adolescent treatment. The other conditions listed in this question might or might not lead to delayed treatment, but they aren’t the major reason for delay.

Question 6

Preadolescent expansion to correct dental crowding usually involves what sort of appliance?

1. Fixed jackscrew to widen the maxilla ✓
2. Lingual arch to move incisors forward
3. Functional appliance to hold mandible forward
4. Removable expanders to widen both arches
5. All of the above

Correct

That’s right, early expansion usually involves a jackscrew appliance to widen the upper arch by opening the midpalatal suture, which is followed later by a complete fixed appliance in both arches. A lingual arch is used much more to maintain space than to throw incisors forward. Functional appliances to guide growth are irrelevant in treatment of crowding/protrusion problems. Removable expanders are possible, but removable appliances to move teeth are so much less effective than fixed appliances that they are rarely used now.

Incorrect

No, that’s wrong. Early expansion usually involves a jackscrew appliance to widen the upper arch by opening the midpalatal suture, which is followed later by a complete fixed appliance in both arches. A lingual arch is used much more to maintain space than to throw incisors forward. Functional appliances to guide growth are irrelevant in treatment of crowding/protrusion problems. Removable expanders are possible, but removable appliances to move teeth are so much less effective than fixed appliances that they are rarely used now.

Question 7

Which of the following criteria should a patient meet to become a candidate for serial extraction starting at age 8?

a. Lack of space for alignment of lateral incisors

b. >9 mm crowding in both arches

c. Normal facial proportions

d. Fixed appliance treatment available later

1. a and b
2. b and c
3. c and d
4. a, b, and c
5. all of the above ✓

Correct

That’s right, an 8-year-old child isn’t a candidate for serial extraction unless all these criteria are met. The rule on starting serial extraction, which usually involves extraction of primary canines so lateral incisors can erupt, is simple: “If in doubt, don’t!”

Early extraction of primary canines in a child who doesn’t meet the criteria can greatly complicate appropriate treatment later. But for the limited number of children who do meet all the criteria, serial extraction can be effective and reasonably efficient treatment. So once all doubt has been removed, it’s perfectly acceptable.

Incorrect

No, that’s wrong. An 8-year-old child isn’t a candidate for serial extraction unless all these criteria are met. The rule on starting serial extraction, which usually involves extraction of primary canines so lateral incisors can erupt, is simple: “If in doubt, don’t!”

Early extraction of primary canines in in a child who doesn’t meet the criteria can greatly complicate appropriate treatment later. But for the limited number of children who do meet all the criteria, serial extraction can be effective and reasonably efficient treatment. So once all doubt has been removed, it’s perfectly acceptable.

Question 8

In a patient with a moderate space discrepancy, which of the following are criteria for placement of a lingual arch to maintain space during the early mixed dentition?

a. Loss of primary molar to caries

b. Spontaneous loss of one or both primary canines

c. Posterior crossbite

d. Anterior open bite

1. a and b ✓
2. b and c
3. c and d
4. a, b, and c
5. All the above

Correct

That’s right. Early treatment, consisting of a lingual arch to maintain space, is needed for a child with moderate crowding who loses a primary molar to caries or one or both primary canines spontaneously (which can happen as the permanent laterals erupt). Neither posterior crossbite nor anterior open bite are indications for a lingual arch at an early age.

Incorrect

That’s wrong. Early treatment, consisting of a lingual arch to maintain space, is needed for a child with moderate crowding who loses a primary molar to caries or one or both primary canines spontaneously (which can happen as the permanent laterals erupt). Neither posterior crossbite nor anterior open bite are indications for a lingual arch at an early age.

Question 9

Why is it recommended to start comprehensive (fixed appliance) treatment for Class I crowding/protrusion just before the second primary molars are lost?

1. The uncooperative phase of adolescence starts then.
2. The adolescent growth spurt usually occurs then.
3. Freeway space decreases at that point.
4. Leeway space is lost when the second primary molars are lost. ✓

Correct

That’s right. In patients with moderate crowding, maintaining the leeway space (the difference in size between second primary molars and second premolars) provides valuable space for aligning the other teeth, often enough that further arch expansion is unnecessary.

The growth spurt doesn’t affect the dentition. Uncooperative behavior isn’t a good answer to this question, even though it’s true that adolescence makes behavior less predictable and often less pleasant for authority figures (which includes the dentist, unfortunately). Freeway space (the difference between the intercuspal and postural positions of the mandible) doesn’t change when 2nd primary molars are lost.

Incorrect

No, that’s wrong. In patients with moderate crowding, maintaining the leeway space (the difference in size between second primary molars and second premolars) provides valuable space for aligning the other teeth, often enough that further arch expansion is unnecessary.

The growth spurt doesn’t affect the dentition. Uncooperative behavior isn’t a good answer to this question, even though it’s true that adolescence makes behavior less predictable and often less pleasant for authority figures (which includes the dentist, unfortunately). Freeway space (the difference between the intercuspal and postural positions of the mandible) doesn’t change when 2nd primary molars are lost.

Question 10

What percentage of the patients treated in the clinical trial of early vs late Class II treatment showed a favorable response, in terms of an improvement in the jaw relationship?

1. 25%
2. 50%
3. 75% ✓

4. 90% of those who cooperated

Correct

That’s right, about 75% of the children showed a highly favorable or favorable response, as evaluated by a reduction in the ANB angle that measures the difference in prominence of the upper and lower jaws.

There is no way to be sure precisely how cooperation influenced this number, except that it is not the only reason for failure to respond. You can’t take for granted that whatever the growth modification approach, it would have succeeded if the child had cooperated.

Incorrect

No, that’s wrong. About 75% of the children showed a highly favorable or favorable response, as evaluated by a reduction in the ANB angle that measures the difference in prominence of the upper and lower jaws.

There is no way to be sure precisely how cooperation influenced this number, except that it is not the only reason for failure to respond. You can’t take for granted that whatever the growth modification approach, it would have succeeded if the child had cooperated.

Question 11

In randomized clinical trials of early vs later Class II treatment, after comprehensive phase 2 treatment for both the previously treated and untreated children, how do the PAR scores compare?

1. Much lower in the previously treated group
2. A little lower in the previously treated group
3. About the same ✓
4. A little higher in the previously treated group
5. Much higher in the previously treated group

Correct

That’s right, after phase 2 treatment, PAR scores (which reflect how well the teeth are aligned and how well they fit together) were remarkably similar in the previously treated and untreated Class II children, both in mean scores and in the percentages with excellent/good/disappointing results. PAR scores are like golf scores, lower is better; so for all the groups, there was a similar improvement in occlusion with treatment.

Incorrect

No, that’s wrong. After phase 2 treatment, PAR scores (which reflect how well the teeth are aligned and how well they fit together) were remarkably similar in the previously treated and untreated Class II children, both in mean scores and in the percentages with excellent/good/disappointing results. PAR scores are like golf scores, lower is better; so for all the groups, there was a similar improvement in occlusion with treatment.

Question 12

Which of the following now are considered valid reasons for early Class II treatment?

a. Unusually severe problems

b. Evidence of major social problems from teasing, etc.

c. Tissue damage from the bad bite

d. Maternal anxiety about waiting for treatment

1. a and b
2. b and c
3. c and d
4. a, b, and c ✓
5. all of the above

Correct

That’s right. Unusually severe problems, major social problems, and the presence of tissue damage from the malocclusion are now considered valid reasons for early Class II treatment. Maternal anxiety isn’t. Orthodontics as a form of psychotherapy for mothers is not good treatment for the mother or the child.

Incorrect

No, that’s wrong. Unusually severe problems, major social problems, and the presence of tissue damage from the malocclusion are now considered valid reasons for early Class II treatment. Maternal anxiety isn’t. Orthodontics as a form of psychotherapy for mothers is not good treatment for the mother or the child.

Question 13

Which of the following are problems with early treatment to restrain excessive mandibular growth?

a. Minimally effective

b. Any effect tends to be lost to continued growth

c. Treatment has to be continued until the late teens

d. Early orthognathic surgery is a better alternative

1. a and b
2. b and c
3. c and d
4. a, b, and c ✓
5. all of the above

Correct

That’s right, problems with early treatment to restrain excessive mandibular growth are that it’s minimally effective, doesn’t work very well. Any effects it does achieve tend to be lost to rebound growth unless the treatment is continued for a decade or more, well into the late teens, and even then it may not work.

But early orthognathic surgery isn’t a better alternative. Excessive growth is likely to continue even after surgery if it is done too soon, so the surgery has to wait, often until the late teens, until growth finally slows to adult levels.

Incorrect

No, that’s wrong. Problems with early treatment to restrain excessive mandibular growth is that it’s minimally effective, doesn’t work very well. Any effects it does achieve are lost to rebound growth unless the treatment is continued for a decade or more, well into the late teens—and even then it may not work.

But early orthognathic surgery isn’t a better alternative. Excessive growth is likely to continue even after surgery if it is done too soon—so the surgery has to wait, often until the late teens, until growth finally slows to adult levels.

Question 14

Why is it so important for a maxillary deficient child to start treatment early?

1. Above about age 8, forward displacement of the maxilla becomes impossible. ✓
2. It is much easier to move the upper incisors forward just as they are erupting.
3. Only quite young children can be persuaded to cooperate with wearing a face mask.
4. It isn’t—waiting until the adolescent growth spurt is the most efficient approach.

Correct

That’s right, it’s important to start this treatment early because the window of opportunity to produce skeletal change closes about age 8. After that, the sutures of the maxilla become so interdigitated that displacing it forward is no longer possible.

Moving the upper incisors forward is not the goal of treatment, skeletal change is. Older children can be persuaded to wear a face mask, it just doesn’t work as well or often at all. For most problems waiting until the adolescent growth spurt is the most efficient approach to treatment. Maxillary deficiency is the prime exception to that rule.

Incorrect

That’s wrong. It’s important to start this treatment early because the window of opportunity to produce skeletal change closes about age 8. After that, the sutures of the maxilla become so interdigitated that displacing it forward is no longer possible.

Moving the upper incisors forward is not the goal of treatment, skeletal change is. Older children can be persuaded to wear a face mask, it just doesn’t work as well or often at all. For most problems waiting until the adolescent growth spurt is the most efficient approach to treatment. Maxillary deficiency is the prime exception to that rule.