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Incisor trauma and early treatment for Class II Division 1 malocclusion
ORIGINAL ARTICLE
Incisor trauma and early treatment for Class II Division 1 malocclusion Lorne D. Koroluk, DMD, MSD, MS, FRCD(C),a J. F. Camilla Tulloch, BDS, FDS,b and Ceib Phillips, PhDb Chapel Hill, NC This study investigated incisor trauma in children with overjets greater than or equal to 7 mm who were enrolled in a clinical trial of 2-phase early orthodontic treatment for Class II malocclusion. In phase 1, children were randomly assigned to treatment in the mixed dentition with either modified bionator or combination headgear or to a group in which treatment was delayed until the permanent dentition. All children received comprehensive treatment during phase 2 if necessary. At the start of the trial, 29.1% of the patients had already had some incisor trauma. This was not significantly related to dental developmental age. During the trial, there was an increase in trauma in all 3 groups, but the magnitude of this increase was not significantly greater in the group for which treatment was delayed until the permanent dentition. This might suggest that orthodontic intervention aimed at reducing trauma should begin very soon after the eruption of the maxillary incisors. However, the injuries tended to be minor, and the expected cost of treatment related to incisor trauma was small compared with the expected additional cost of a 2-phase orthodontic intervention. (Am J Orthod Dentofacial Orthop 2003;123:117-26)
I
ncisor protrusion, maxillary prominence, Class II Division 1 malocclusion, and lip coverage have all been identified as possible predisposing factors for incisor trauma. An increased risk of incisor trauma has been well documented in children with an overjet greater than 6 mm.1-3 Orofacial trauma can result in a wide spectrum of dental injuries ranging from enamel crown fractures with good prognoses to complex injuries with reduced long-term prognoses. Early orthodontic treatment for children with Class II malocclusions and large overjets has been recommended as a method of preventing incisor trauma and its related long-term sequelae. The efficacy of such intervention is intimately related to its timing and the peak occurrence of incisor trauma. The benefits of early orthodontic intervention to prevent dental trauma can be questioned if most trauma occurs before the start of orthodontic treatment in the middle to late mixed dentition.4 Subjects of this study were initially enrolled in a clinical trial designed to study early growth modification in the treatment of Class II malocclusion. The From the Department of Orthodontics, School of Dentistry, University of North Carolina at Chapel Hill. a Associate Professor. b Professor. Supported by NIH grant DE 08708. Reprint requests to: Dr Lorne D. Koroluk, University of North Carolina at Chapel Hill, School of Dentistry, CB #7450, Department of Orthodontics, Chapel Hill, NC 27599-7450; e-mail, [email protected]. Submitted, January 2002; revised and accepted, May 2002. Copyright © 2003 by the American Association of Orthodontists. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.86
purposes of this study were to (1) describe the prevalence, extent, and severity of incisor trauma in this group of preadolescent children with large overjets; (2) compare the incidence of new incisor trauma in children whose growth modification started in the mixed dentition with those whose treatment was delayed until the early permanent dentition; and (3) compare the costs and risks of increased trauma for children with treatment started in the mixed or permanent dentition periods. METHODS
Data for this study were collected from a randomized clinical trial designed to study the benefits of early growth modification in the treatment of Class II malocclusion. The study design and patient selection are described in detail in previous publications.5-7 In the first phase of the trial, preadolescent children (mean chronological age ⫹ SD, 9.83 ⫾ .99 years; range, 7.9-12.6 years) with increased overjet (ⱖ7 mm) were randomly assigned (in blocks of 6, stratified by sex) to undergo early growth modification (modified bionator or combination headgear) or no treatment during an observation period. In accordance with a strict treatment protocol, 1 clinician provided all phase 1 treatment. All patients were evaluated at 15 months and kept in their assigned groups until their deciduous teeth were lost. During phase 2, the patients were once again randomized (in blocks of 8) stratified on the basis of their phase 1 group assignment to 1 of 4 doctors for completion of treatment. All children received compre117
118 Koroluk, Tulloch, and Phillips
Fig 1. Incisor trauma criteria.
hensive orthodontic treatment in the permanent dentition as considered necessary during the second phase of the trial. The criteria for inclusion in the study were moderate to severe overjet (ⱖ7 mm) (mean overjet, 9.29 mm ⫾ 2.0 mm SD; range, 7-15 mm), all permanent incisors and first molars erupted, and more than 1 year prepeak height velocity as determined by a hand-wrist radiograph. Patients with congenital syndromes, obvious facial asymmetry, extreme vertical disproportion, or history of prior orthodontic treatment including space maintenance and habit appliances were excluded from the trial. Orthodontic records were obtained for each patient at the start of the trial, after 15 months, and after the completion of orthodontic treatment. Incisor trauma was assessed by clinical examination at each stage of the study by the same research technician, who used incisor trauma criteria modified from the Third National Health and Nutrition Examination Survey (NHANES III)8 (Fig 1). Dental age at the start of the trial was determined with a method developed by Demirjiam et al9 in which each of the mandibular left permanent teeth, excluding the third molar, as viewed on a panoramic radiograph was assigned a developmental score on the basis of crown and root development. A computer program developed by the same author (Biological Age, Silver Platter Education Inc, Norwood, Mass) was used to calculate an overall dental age for
American Journal of Orthodontics and Dentofacial Orthopedics February 2003
each patient by entering the individual scores for each of the left mandibular permanent teeth. The McNemar test for paired binomial responses was used to compare the occurrence of trauma in mandibular and maxillary incisors, in lateral and central incisors, or in phase 1 and phase 2, because these comparisons are within a subject. The Fisher exact test was used to compare the occurrence of trauma between mutually exclusive groups (eg, the 3 treatment groups; males and females; or the 4 dental age groups), because the sample size for positive responses was small. The Mantel Haenszel row mean score test was used to compare the number of teeth and the summary severity score among the treatment groups, because these outcomes are quantitative but do not meet the assumptions of the unpaired t test. The cost of treating any new incisor trauma during the clinical trial was determined with a range of possible treatment options for each trauma category (Fig 2) and treatment costs from published American Dental Association fee data.10 For example, the minimal intervention procedures for craze lines (category 1) or enamel fractures (category 2) assumed that very minor trauma would have occurred and that no dental treatment or visit would have been required. The maximum intervention assumed that a dental visit occurred, necessary radiographs were taken, treatment was provided, and the recommended follow-up occurred. The maximum intervention also assumed that all enamel fractures would receive a 2-surface resin restoration. On the basis of clinical judgment, it was determined that the 4 teeth in categories 3 and 5 could also be restored with 2-surface resin restorations. In clinical practice, some category 3 and 5 fractures might require more extensive 3- or 4-surface restorations that would be more expensive. Some of these larger resin restorations might also require future, more costly restorations such as crowns or veneers. Such potential long-range costs were not included in the model, because in this trial, only 4 teeth could possibly require such future treatment, and the probability of the treatment could not be accurately estimated. The radiographic and reevaluation procedures for each trauma category were based on clinical protocols suggested by Andreasen and Andreasen,11 which continue to be widely accepted as the standard of care. The 1999 American Dental Association fee survey10 was used to develop a range of possible costs for each trauma category as follows: lowest possible cost (minimal intervention; fees based on the 10th percentile general practice fees), highest possible cost (maximum intervention; fees based on the 90th percentile general practice fees), and midrange cost (an average of the fees
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Fig 2. Clinical procedures used in cost analysis.
for maximum and minimum intervention; based on the mean general practice fees). If procedure codes were not listed in the fee survey, costs were estimated by using similar procedure codes with known local and American Dental Association fees. Trauma present at the initial evaluation was not included. The expected cost of incisor trauma per child during the trial was calculated by multiplying the possible cost of treatment for each trauma category by the frequency with which each trauma category occurred and then summing the results for all 7 trauma categories. The expected cost gives a comparison of the costs that might result from increased trauma if orthodontic treatment were begun in the mixed dentition or delayed until the permanent dentition.
RESULTS
Of the 179 patients (105 boys; 74 girls) who had initial records, 163 with complete trauma data (61, observation only; 52, functional appliance; and 50, headgear) completed phase 1 of the trial. During phase 2, 139 of these patients started and completed comprehensive treatment with fixed appliances (51, control; 42, functional appliance; and 46, headgear). At baseline, only 3 patients from the group had trauma to the mandibular incisors, and 1 patient had trauma to both the mandibular and maxillary incisors. The number of patients with maxillary incisor trauma was significantly greater than the number with mandibular incisor trauma (P ⬍ .001, McNemar test). Because
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Table I. Prevalence of traumatized maxillary incisors at baseline clinical evaluation
Trauma category 1 and 2 Craze lines; enamel only 3 Enamel and dentine 5 Restored fracture Total
Prevalence of traumatized maxillary incisors by dental age at baseline (before phase 1)
Table II.
Right Right Left Left lateral central central lateral Patients 2
21
18
4
37
0
1
0
0
1
1
8
10
0
15
3
30*
28*
4
53
Dental age
n
Number of patients with trauma
⬍9 9-9.9 10-10.9 ⱖ11
33 59 43 43
9 20 11 12
Percentage of dental age group with trauma*
Number of patients with trauma in ⬎1 tooth
27.3 33.9 25.6 27.9
2 0 4 3
n ⫽ 179 (105 males; 74 females). *Maxillary central incisors (58) had significantly more trauma than maxillary lateral incisors (7) (P ⬍ .001, McNemar test).
Total n ⫽ 178; mean dental age, 10.03 ⫾ 1.25 years (SD). Unable to determine dental age of 1 patient because of the lack of baseline panoramic radiograph. *No significant difference (P ⫽ .84, Fisher exact test).
mandibular trauma was so infrequent, only new maxillary incisor trauma was reported in this study. The prevalence of traumatized maxillary incisors and the number of patients with maxillary incisor trauma at baseline are shown in Table I. Forty-seven patients had maxillary central incisor trauma, 4 had maxillary lateral incisor trauma, and 2 had both maxillary central and lateral incisor trauma. The number of patients with maxillary central incisor trauma was significantly greater than patients with maxillary lateral incisor trauma (P ⬍ .001, McNemar test). At the start of the trial, there was no significant difference in the proportion of patients with and without maxillary incisor trauma by sex (P ⫽ .41, Fisher exact test) or by early treatment group (P ⫽ .08, Fisher exact test). Furthermore, the extent (number of maxillary teeth with trauma per child) (P ⫽ .31, Mantel Haenszel row mean score) and severity (sum of the trauma scores for each child) (P ⫽ .74, Mantel Haenszel row mean score) of trauma were not significantly different among the 3 groups. Because the children’s incisors might have been erupted for different lengths of time before the study, the prevalence of traumatized maxillary incisors at the time of initial records is shown in Table II by dental developmental age. No significant difference was found in the proportion of patients with and without maxillary incisor trauma among the 4 dental age categories (P ⫽ .84, Fisher exact test). The proportion of patients with trauma remained relatively stable throughout the late mixed and early permanent dentition. The incidence of new maxillary incisor trauma during phase 1 of the trial is shown in Table III. During the first phase of the trial, 16 patients sustained new trauma to 17 teeth. Within the groups, this change in incisor trauma was statistically different from 0 for both the control and the headgear groups, but not for the
functional appliance group, although the incidence in this group was only slightly smaller than that of the other groups. However, among the 3 early treatment groups, there was no statistically significant difference in the proportion of patients with and without new maxillary incisor trauma. This apparent lack of difference in the magnitude of the change among the 3 groups might be a function of the relatively small samples considered. The new trauma was generally minor; only 3 teeth required resin restorations. There was no significant difference in new maxillary incisor trauma between boys and girls during phase 1(P ⫽ .27, Fisher exact test). Additional incisor trauma also occurred in the second phase of the trial during comprehensive orthodontic treatment and is shown in Table IV. During this phase, 21 patients sustained new trauma to their maxillary incisors. This change in incisor trauma was statistically different from 0 for the control group, but not for the headgear and the functional appliance groups. Again, there was no significant difference in the proportion of patients with and without new maxillary incisor trauma among the 3 early treatment groups. As in phase 1, most new injuries tended to result in craze lines or enamel-only fractures. Only 1 patient required a resin restoration; another patient required endodontic treatment of a maxillary central incisor that had evidence of craze lines at the end of phase 1. There was no significant difference in new maxillary incisor trauma between boys and girls during phase 2 of the trial (P ⫽ .35, Fisher exact test). At baseline records, there was no significant difference between the mean overjet of patients with maxillary incisor trauma (9.50 ⫾ 2.28 mm, mean ⫾ SD) and patients without maxillary incisor trauma (9.22 ⫾ 1.89 mm) (P ⫽ .42, unpaired t test). There was a statistically significant difference in the mean overjet change
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Table III.
New maxillary incisor trauma during phase 1 Control* (n ⫽ 61)
Trauma category 1 and 2 Craze lines; enamel only 3 Enamel and dentine 5 Restored fracture Total
Functional* (n ⫽ 52)
Headgear* (n ⫽ 50)
Laterals
Centrals
Patients
Laterals
Centrals
Patients
Laterals
Centrals
Patients
0
7
7
0
3
3
0
4
3
0
0
0
0
0
0
0
0
0
0
2
2
0
0
0
0
1
1
0
9
9
0
3
3
0
5
4
*No significant difference in proportion of patients with and without new maxillary incisor trauma (P ⫽ .29 Fisher exact test). Statistically significant increase in presence of maxillary incisor trauma in control group (P ⫽ .002) and headgear group (P ⫽ .03) but not functional appliance group (P ⫽ .13) (McNemar 1-tailed test). Table IV.
New maxillary incisor trauma during phase 2 Control* (n ⫽ 51)
Trauma category 1 and 2 Craze lines; enamel only 3 Enamel and dentine 5 Restored fracture Total
Functional* (n ⫽ 42)
Headgear* (n ⫽ 46)
Laterals
Centrals
Patients
Laterals
Centrals
Patients
Laterals
Centrals
Patients
3
11
11
5
3
5
0
6
4
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
12
12
5
3
5
0
6
4
*No significant difference in proportion of patients with and without new maxillary incisor trauma (P ⫽ .12, Fisher exact test). Statistically significant increase in presence of maxillary incisor trauma in control group (P ⫽ .004) but not headgear group (P ⫽ .06) or functional appliance group (P ⫽ .19) (McNemar 1-tailed test) during phase 2. One additional control patient required endodontic treatment of maxillary right central incisor (end of phase 1 score of 1 [enamel fracture] to end of phase 2 score of 6 [lingual restoration indicative of endodontic access]).
among the 3 groups during both phase 1 (P ⫽ .0001, 1-way analysis of variance [ANOVA]) and phase 2 (P ⫽ .0001, 1-way ANOVA) (Fig 3). Table V shows the probability of each trauma category that occurred during phases 1 and 2 of the trial and the range of fees associated with each trauma category. The expected cost of trauma per patient in the control and the treatment groups during the entire trial is shown in Table VI. DISCUSSION
Even minor dental trauma can lead to significant complications despite appropriate initial treatment.12-15 The prognosis for traumatized teeth can be guarded for a long time after the initial injury. A rational approach to dental trauma would be to prevent or reduce these injuries rather than to treat the resulting significant immediate and long-term sequelae. The prevalence of recorded dental trauma has varied from 4% to 30% of children in previous studies.15 This clinical trial confirmed findings that the
incidence of incisor trauma in children with Class II malocclusion is high.1-3 A significant amount of incisor trauma occurred before the start of the trial; approximately one-third of the children with a dental age of less than 9 years had incisor trauma at the start of the trial. A more accurate determination of the time of initial incisor trauma would require a longitudinal study of a larger group of younger children enrolled at the dental age of 5 or 6 years. These age-related findings are similar to those of a longitudinal study of Danish children from birth to 14 years of age, in which 30% of them sustained injuries to the deciduous dentition, and 22% had injuries to the permanent dentition.16 The incidence of dental trauma has been shown to increase between 2 and 4 years of age in the deciduous dentition for boys and girls and between 8 and 10 years of age in the permanent dentition for boys.16,17 In this study, the prevalence of incisor trauma by dental developmental age rather than chronological age was shown at baseline records before phase 1 treatment as a proxy measure for the length of
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Fig 3. Change in overjet during phases 1 and 2.
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Table V.
Probability of additional trauma during entire trial and ranges of possible fees for trauma categories Probability of trauma during entire trial
Range of fees for trauma categories ($)
Trauma category
Control
Functional
Headgear
Low
Mid
High
1 2 3 5 6
0.0392 0.2912 0.0196 0.0327 0.0196
0.0476 0.1291 0 0 0
0.0434 0.1035 0 0.0200 0
0.00 0.00 107.00 107.00 382.00
67.15 117.04 234.08 234.08 640.51
194.00 334.00 443.00 443.00 1000.00
163 patients completed phase 1; 139 patients completed phase 2. Probability (entire trial) ⫽ probability (phase 1) ⫹ probability (phase 2).
Expected cost of trauma for patients who received early treatment with headgear and functional appliance compared with treatment delayed until permanent dentition
Table VI.
Expected cost range ($) Group
Low
Mid
High
Control Functional Headgear
13.10 0.00 2.14
60.56 18.31 19.70
147.70 52.03 51.85
Expected Cost ⫽ ⌺ (probability of trauma category) ⫻ (estimated fee for trauma category) for low, mid, and high ranges. For example, expected cost (low range) for control group (from Table V) ⫽ (0.0392)(0.00) ⫹ (0.2912)(0.00) ⫹ (0.0196)(107.00) ⫹ (0.0327)(107.00) ⫹ (0.0196)(382.00) ⫽ 13.10.
time the incisors had been erupted. The implications of the relationship between incisor trauma and the age of occurrence are crucial to the discussion of the efficacy of early orthodontic correction of severe overjet to reduce the risk of incisor trauma. The proportion of patients with maxillary incisor trauma at baseline records was not significantly different among the 4 dental developmental age categories, tempting one to conclude that a significant amount of the maxillary incisor trauma does occur early, shortly after the permanent incisors erupt. Thus, if early treatment is planned to prevent incisor trauma, it should be undertaken soon after these teeth erupt. However, the risks and costs of this approach must also be considered. In this study, the proportion of patients with and without maxillary incisor trauma at the time of baseline records was not significantly different between boys and girls. This is contrary to other findings, which have generally suggested an increased prevalence of incisor trauma in boys,18-20 but similar to those of GarciaGodoy et al.21 As in previous studies, the susceptibility of teeth to trauma was related to their position in the dental
arches.22 The maxillary incisors were found to have a much higher prevalence and incidence of trauma than the mandibular incisors, and the maxillary central incisors had a higher prevalence and incidence of trauma than did the maxillary lateral incisors. A high proportion of these patients incurred damage to their incisors before and during this investigation. However, most trauma was minor, consisting of enamel fractures and craze lines with good long-term prognoses.13,15 Improvements in resin bonding materials and techniques have greatly simplified the way clinicians treat minor incisor trauma. During the trial, only 1 tooth received trauma severe enough to require endodontic treatment. The main objective of the trial was to assess the possibility of growth changes during early treatment for Class II malocclusion, not to assess the benefit of early correction of overjet. In addition, the headgear and functional appliances used during the first phase of the trial produced different incisor effects. The functional appliance, although designed to prevent tipping, tended to have a direct effect on the maxillary incisors; this resulted in a significantly greater reduction of overjet during phase 1 compared with the headgear and the control groups, in which most overjet correction was completed during phase 2. During phase 1, the incidence of incisor trauma was statistically significant in the control and headgear groups, but not in the functional appliance group. During phase 2, the incidence of incisor trauma was statistically significant in the control group but not in the functional appliance or the headgear groups. The difference in the incidence of trauma was not significantly different between the groups during phases 1 and 2. During phase 1, without treatment, the control group experienced the largest increase in incisor trauma and only minor reduction in overjet, whereas the functional appliance group experienced less new maxillary incisor trauma and had the largest reduction in overjet. These
124 Koroluk, Tulloch, and Phillips
findings might suggest that early orthodontic treatment specifically designed to reduce overjet can affect the incidence of maxillary incisor trauma in children. In patients with increased overjet due to maxillary dentoalveolar protrusion, early orthodontic treatment with a 2 ⫻ 4 appliance or Hawley appliance with an active labial bow can be started shortly after the eruption of the central incisors at approximately age 7 years to reduce overjet. This early treatment would not necessarily be considered a growth modification phase if the increased overjet was dentoalveolar. A clinical trial would have to be designed to test the effectiveness of such early dentoalveolar intervention in preventing future early incisor trauma. Considering the costs of treating trauma, a wide range of estimates for the additional associated treatment costs has been presented. Combining cost data with the likelihood of a child sustaining different types of trauma suggests that the expected costs (cost of treating trauma ⫻ probability of trauma) are very similar for the 2 early treatment groups and higher for the patients receiving no early treatment, whether the low, medium, or high estimated costs are used. However, this increase in expected costs must be balanced with the almost certain increased cost of 2-stage orthodontic treatment. For most patients in this study, the cost of restoring the damaged incisors was minor compared with the increased fees generally associated with 2-phase early orthodontic treatment. A significant proportion of the high-range cost per child was related to extensive treatment for enamel fractures that might more realistically receive enamoplasty or no treatment at all. The low to midrange cost per child appears to be a more clinically realistic representation of the true cost of trauma per patient. Indeed, in this trial, most injuries were minor and easily treated at low cost with good long-term prognosis. Cost calculations were structured to reflect the relative short-term costs of incisor trauma, but all restorations have a real clinical life span. Larger category 3 and 5 fractures might require future replacement with more expensive veneers or crowns, thus increasing the expected cost. There were a minimal number of category 3 and 5 fractures that might require further long-term treatment; therefore, these costs were not included in the model because these small frequencies would not significantly affect the results of the analysis. Also, the life span of bonded resins has increased significantly with the advent of new bonding materials and techniques. From a public health perspective, the feasibility of early orthodontic treatment as a policy to reduce the incidence of trauma in all children with overjets greater
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than 7 mm would be financially prohibitive, because the orthodontic intervention would have to be very early and almost certainly followed by a second phase of treatment, and it would cost much more than the treatment of any possible incisor trauma. However, for an individual patient, the choices are more complex. Parents might elect early orthodontic treatment that reduces overjet to possibly decrease the likelihood of major incisor trauma and future trauma-related expenses. Nondental variables such as risk-taking behavior and increased physical activity can also place children at risk for incisor trauma regardless of the position of the incisors. Although all the children in this study had overjets greater than 7 mm, they did not have similar incisor trauma experiences. It is possible that a threshold overjet might exist, above which a child has an increased risk of incisor trauma. Other social and behavioral factors might place a susceptible child in the right environment to ultimately traumatize the teeth. The sample followed here was of insufficient size to permit such subgroup analysis. Only simple bivariate statistical analysis was used on the data from this clinical trial because the relative sample sizes of patients with and without trauma precluded using logistic regression analysis. As a result, the combination effect of multiple variables might be significant (ie, dental or chronologic age combined with sex), whereas the individual variables alone show no association with trauma. Although data analysis is not yet complete, the oral health, measured as periodontal indexes and enamel lesions, of children who had early treatment in this trial does not appear dissimilar from those for whom orthodontic treatment was delayed until their permanent dentition. Currently, another project is underway to evaluate whether teeth that have sustained trauma are at greater risk of root resorption than those that have not. CONCLUSIONS
The following conclusions can be made from this study of orthodontic treatment in preadolescent patients with Class II Division 1 malocclusions: 1. A significant number of patients had trauma to the maxillary incisors, but the injuries were minor. Most of the new injuries were minor and could easily be treated at low cost and with good long-term prognoses. 2. Early growth modification treatment might have some effect on the incidence of trauma, but to be effective it might have to be initiated soon after the eruption of the maxillary incisors. 3. The expected cost of trauma per child was less for
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patients who had early growth modification treatment than for patients whose treatment was delayed until their permanent dentition, but this expected difference must be balanced with the usually greatly increased cost of 2-phase early orthodontic treatment. REFERENCES 1. Dearing SG. Overbite, overjet, lip-drape and incisor tooth fracture in children. NZ Dent J 1984;80:50-2. 2. Ghose LJ, Baghdady VS, Enke H. Relation of traumatized permanent anterior teeth to occlusion and lip condition. Community Dent Oral Epidemiol 1980;8:381-4. 3. O’Mullane DM. Some factors predisposing to injuries of permanent incisors in school children. Br Dent J 1973;134:328-32. 4. King GJ, Keeling SD, Hocevar RA, Wheeler TT. The timing of treatment for Class II malocclusion in children: a literature review. Angle Orthod 1990;60:87-97. 5. Tulloch JFC, Phillips C, Koch G, Proffit WR. The effect of early intervention on skeletal pattern in Class II malocclusion: a randomized clinical trial. Am J Orthod Dentofacial Orthop 1997;111:391-400. 6. Tulloch JFC, Proffit WR, Phillips C. Influences on the outcome of early treatment for Class II malocclusion. Am J Orthod Dentofacial Orthop 1997;111:533-42. 7. Tulloch JFC, Phillips C, Proffit WR. Benefit of early Class II treatment: progress report of a two-phase randomized clinical trail. Am J Orthod Dentofacial Orthop 1998;113:62-72. 8. National Center for Health Statistics. NHANES III dental examiner’s manual. Hyattsville (Md): Westat, Inc; 1992. 9. Demirjiam A, Goldstein H, Tanner JM. A new system of dental age assessment. Hum Biol 1973;45:211-27. 10. American Dental Association. The 1999 survey of dental fees. Chicago: American Dental Association Survey Center; 1999. 11. Andreasen JO, Andreasen FM. Essentials of traumatic injuries to the teeth. Copenhagen: Munksgaard; 1990. p. 11-45. 12. Andreasen FM, Pedersen BV. Prognosis of luxated permanent teeth—the development of pulp necrosis. Endod Dent Traumatol 1985;1:207-20. 13. Zadik D, Chosack A, Eidelman E. The prognosis of traumatized permanent anterior teeth with fracture of enamel and dentin. Oral Surg Oral Med Oral Pathol 1979;47:173-5. 14. Hedegard B, Stalhane I. A study of traumatized permanent teeth in children aged 7-15 years. Swed Dent J 1973;66:431-50. 15. Andreasen JO. Traumatic injuries of the teeth. 2nd ed. Copenhagen: Munksgaard; 1981. p. 40, 78, 227. 16. Andreasen JO, Ravn JJ. Epidemiology of traumatic dental injuries to primary and permanent teeth in a Danish population sample. Int J Oral Surg 1972;1:235-9. 17. Mullane DM. Injured permanent incisor teeth: an epidemiological study. J Ir Dent Assoc 1972;18:160-73. 18. Kaste LM, Gift HC, Bhat M, Swango PA. Prevalence of incisor trauma in persons 6-50 years of age: United States, 1988-1991. J Dent Res 1996;75:696-705. 19. Kania MJ, Keeling SD, McGorray SP, Wheeler TT, King GJ. Risk factors associated with incisor injury in elementary school children. Angle Orthod 1996;66:423-32. 20. Ravn JJ. Dental injuries in Copenhagen schoolchildren, school years 1967-1972. Community Dent Oral Epidemiol 1974;2:23145. 21. Garcia-Godoy F, Sanchez R, Sanchez J. Traumatic dental inju-
ries in a sample of Dominican school children. Community Dent Oral Epidemiol 1981;9:193-217. 22. Gutz DP. Fractured permanent incisors in a clinic population. J Dent Child 1971;38:94-121.
COMMENTARY
A quick MEDLINE search for overjet, incisor trauma, and Class II malocclusion yields a list of more than 100 references. Obviously, the subject is both of considerable interest to the dental profession and well studied. So why would the American Journal of Orthodontics and Dentofacial Orthopedics want to publish yet another article on this subject? Any new work on the topic must offer more than an epidemiologic look at the incidence and prevalence of incisor trauma among children, and this article does. When an orthodontist recommends an early phase of treatment, there should be clear benefits for the consumer. These benefits might include increased stability, reduced treatment time in the second phase, reduced risk of future problems, or reduced costs. The epidemiologic data indicate that children with excessive overjet are more prone to incisor trauma, and an orthodontist might recommend early treatment to reduce the excessive overjet and to minimize the risk of incisor trauma. On the other hand, there is a trend toward delaying the correction of the Class II malocclusion until the late mixed dentition period. Prospective studies, including those from the University of North Carolina, do not make a strong argument for an early phase of orthopedic treatment to reduce a Class II malocclusion. However, is reducing incisor overjet a benefit of early treatment that we can “hang our hat on”? This article is based on a sample from a University of North Carolina prospective study on the efficacy of early Class II correction with either bionator functional appliance or headgear versus no early treatment. Both groups were treated with fixed appliances later. The prevalence, extent, and severity of incisor trauma were recorded for all 3 groups at baseline, and they were evaluated 15 months later to compare the incidence of new incisor trauma. Finally, the costs and risks of increased incisor trauma were compared for each group. At baseline, 29.6% of the patients already had trauma to at least 1 incisor. Of these, 8.4% already had restorations. Most of the others had only craze lines or enamel fractures. During the next 15 months of phase I treatment (or observation of the untreated control group), 9.8% of the patients had new fractures of at least 1 incisor. The majority were simple craze lines or enamel fractures. Interestingly, these were greater in
126 Koroluk, Tulloch, and Phillips
the control and the headgear groups than in the bionator group. The authors attribute this to the uprighting of the maxillary incisors from the labial bow of the bionator. During phase II treatment with fixed appliances, an additional 15.1% of the patients experienced a new fracture of at least 1 incisor. Nearly all of these were craze lines or simple enamel fractures. The authors calculated the expected cost of new incisor trauma as the probability of trauma for each group multiplied by the estimated fee for the treatment. Using the midrange of fees, the authors calculated the cost for the control group at $60.56, whereas the costs for the bionator and the headgear groups were $18.31 and $19.70, respectively; obviously, these amounts are less than the fees most orthodontists would assess for a first phase of treatment. A major shortcoming of this article is the timing of the onset of treatment. The youngest patient in this sample was 7.9 years old, and the mean chronological age was 9.83 years. By then, 29.6% of the sample had some form of trauma to at least 1 of their incisors. If our objective is to treat early to reduce incisor trauma, then we should screen these patients, as the American Association of Orthodontists suggests, closer to age 7 (or earlier). We then should ask what we can do if we see them just after the eruption of the maxillary incisors. Is the overjet caused by maxillary dentoalveolar protrusion or mandibular retrognathia? If dental, will we use fixed or removable appliances to upright maxillary incisors that might not have completely formed roots? If skeletal, will we treat the mandibular retrognathia at age 6 or 7 years? If our treatment philosophy is to treat Class II skeletal problems in the late mixed dentition, would a mouthguard, as recommended by the American Association of Orthodontists, have a significant benefit? Epidemiologic samples tend to be large— often over 1000 —in studies examining incisor trauma and ovejet. The current sample is small by comparison, and some findings might differ because of the sample size.
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For example, many epidemiologic studies show that incisor trauma is more prevalent in boys than in girls. This was not a finding of the present study. The statistical analyses, however, were quite specific and appeared to address this shortcoming. This is not just another article on incisor trauma and overjet. The authors have carefully reaped useful information from a well-documented sample to add another piece to the puzzle of the benefits of early orthopedic treatment. They have also humbly and thoroughly recognized the shortcomings of this sample in predicting the efficacy of early treatment in reducing incisor trauma. They suggest a future clinical trial to look at a younger sample. Tomorrow, will I stop doing early treatment to correct Class II skeletal problems because of this study? No, because many of my Class II skeletal patients also have associated vertical and transverse skeletal problems, making predictable correction in the late mixed dentition too complex. No, because many young girls who have severe Class II skeletal problems also have delayed dental development and are early skeletal maturers; surgical correction or compensation would be the only options if treatment were delayed until the late mixed dentition. No, because my 8- and 9-year-old patients typically cooperate better with removable functional appliance and headgear treatment than my 11and 12-year-old patients. No, because some patients are self-conscious about their excessive overjet and lip incompetency, and some have speech difficulties, and their parents are concerned. On the other hand, tomorrow will I look at these patients a little differently because of this study? I most certainly will. Gary R. Wolf, DDS, MSD Norwalk, Ohio Copyright © 2003 by the American Association of Orthodontists. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.92
Incisor trauma and early treatment for Class II Division 1 malocclusion Lorne D. Koroluk, DMD, MSD, MS, FRCD(C),a J. F. Camilla Tulloch, BDS, FDS,b and Ceib Phillips, PhDb Chapel Hill, NC This study investigated incisor trauma in children with overjets greater than or equal to 7 mm who were enrolled in a clinical trial of 2-phase early orthodontic treatment for Class II malocclusion. In phase 1, children were randomly assigned to treatment in the mixed dentition with either modified bionator or combination headgear or to a group in which treatment was delayed until the permanent dentition. All children received comprehensive treatment during phase 2 if necessary. At the start of the trial, 29.1% of the patients had already had some incisor trauma. This was not significantly related to dental developmental age. During the trial, there was an increase in trauma in all 3 groups, but the magnitude of this increase was not significantly greater in the group for which treatment was delayed until the permanent dentition. This might suggest that orthodontic intervention aimed at reducing trauma should begin very soon after the eruption of the maxillary incisors. However, the injuries tended to be minor, and the expected cost of treatment related to incisor trauma was small compared with the expected additional cost of a 2-phase orthodontic intervention. (Am J Orthod Dentofacial Orthop 2003;123:117-26)
I
ncisor protrusion, maxillary prominence, Class II Division 1 malocclusion, and lip coverage have all been identified as possible predisposing factors for incisor trauma. An increased risk of incisor trauma has been well documented in children with an overjet greater than 6 mm.1-3 Orofacial trauma can result in a wide spectrum of dental injuries ranging from enamel crown fractures with good prognoses to complex injuries with reduced long-term prognoses. Early orthodontic treatment for children with Class II malocclusions and large overjets has been recommended as a method of preventing incisor trauma and its related long-term sequelae. The efficacy of such intervention is intimately related to its timing and the peak occurrence of incisor trauma. The benefits of early orthodontic intervention to prevent dental trauma can be questioned if most trauma occurs before the start of orthodontic treatment in the middle to late mixed dentition.4 Subjects of this study were initially enrolled in a clinical trial designed to study early growth modification in the treatment of Class II malocclusion. The From the Department of Orthodontics, School of Dentistry, University of North Carolina at Chapel Hill. a Associate Professor. b Professor. Supported by NIH grant DE 08708. Reprint requests to: Dr Lorne D. Koroluk, University of North Carolina at Chapel Hill, School of Dentistry, CB #7450, Department of Orthodontics, Chapel Hill, NC 27599-7450; e-mail, [email protected]. Submitted, January 2002; revised and accepted, May 2002. Copyright © 2003 by the American Association of Orthodontists. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.86
purposes of this study were to (1) describe the prevalence, extent, and severity of incisor trauma in this group of preadolescent children with large overjets; (2) compare the incidence of new incisor trauma in children whose growth modification started in the mixed dentition with those whose treatment was delayed until the early permanent dentition; and (3) compare the costs and risks of increased trauma for children with treatment started in the mixed or permanent dentition periods. METHODS
Data for this study were collected from a randomized clinical trial designed to study the benefits of early growth modification in the treatment of Class II malocclusion. The study design and patient selection are described in detail in previous publications.5-7 In the first phase of the trial, preadolescent children (mean chronological age ⫹ SD, 9.83 ⫾ .99 years; range, 7.9-12.6 years) with increased overjet (ⱖ7 mm) were randomly assigned (in blocks of 6, stratified by sex) to undergo early growth modification (modified bionator or combination headgear) or no treatment during an observation period. In accordance with a strict treatment protocol, 1 clinician provided all phase 1 treatment. All patients were evaluated at 15 months and kept in their assigned groups until their deciduous teeth were lost. During phase 2, the patients were once again randomized (in blocks of 8) stratified on the basis of their phase 1 group assignment to 1 of 4 doctors for completion of treatment. All children received compre117
118 Koroluk, Tulloch, and Phillips
Fig 1. Incisor trauma criteria.
hensive orthodontic treatment in the permanent dentition as considered necessary during the second phase of the trial. The criteria for inclusion in the study were moderate to severe overjet (ⱖ7 mm) (mean overjet, 9.29 mm ⫾ 2.0 mm SD; range, 7-15 mm), all permanent incisors and first molars erupted, and more than 1 year prepeak height velocity as determined by a hand-wrist radiograph. Patients with congenital syndromes, obvious facial asymmetry, extreme vertical disproportion, or history of prior orthodontic treatment including space maintenance and habit appliances were excluded from the trial. Orthodontic records were obtained for each patient at the start of the trial, after 15 months, and after the completion of orthodontic treatment. Incisor trauma was assessed by clinical examination at each stage of the study by the same research technician, who used incisor trauma criteria modified from the Third National Health and Nutrition Examination Survey (NHANES III)8 (Fig 1). Dental age at the start of the trial was determined with a method developed by Demirjiam et al9 in which each of the mandibular left permanent teeth, excluding the third molar, as viewed on a panoramic radiograph was assigned a developmental score on the basis of crown and root development. A computer program developed by the same author (Biological Age, Silver Platter Education Inc, Norwood, Mass) was used to calculate an overall dental age for
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each patient by entering the individual scores for each of the left mandibular permanent teeth. The McNemar test for paired binomial responses was used to compare the occurrence of trauma in mandibular and maxillary incisors, in lateral and central incisors, or in phase 1 and phase 2, because these comparisons are within a subject. The Fisher exact test was used to compare the occurrence of trauma between mutually exclusive groups (eg, the 3 treatment groups; males and females; or the 4 dental age groups), because the sample size for positive responses was small. The Mantel Haenszel row mean score test was used to compare the number of teeth and the summary severity score among the treatment groups, because these outcomes are quantitative but do not meet the assumptions of the unpaired t test. The cost of treating any new incisor trauma during the clinical trial was determined with a range of possible treatment options for each trauma category (Fig 2) and treatment costs from published American Dental Association fee data.10 For example, the minimal intervention procedures for craze lines (category 1) or enamel fractures (category 2) assumed that very minor trauma would have occurred and that no dental treatment or visit would have been required. The maximum intervention assumed that a dental visit occurred, necessary radiographs were taken, treatment was provided, and the recommended follow-up occurred. The maximum intervention also assumed that all enamel fractures would receive a 2-surface resin restoration. On the basis of clinical judgment, it was determined that the 4 teeth in categories 3 and 5 could also be restored with 2-surface resin restorations. In clinical practice, some category 3 and 5 fractures might require more extensive 3- or 4-surface restorations that would be more expensive. Some of these larger resin restorations might also require future, more costly restorations such as crowns or veneers. Such potential long-range costs were not included in the model, because in this trial, only 4 teeth could possibly require such future treatment, and the probability of the treatment could not be accurately estimated. The radiographic and reevaluation procedures for each trauma category were based on clinical protocols suggested by Andreasen and Andreasen,11 which continue to be widely accepted as the standard of care. The 1999 American Dental Association fee survey10 was used to develop a range of possible costs for each trauma category as follows: lowest possible cost (minimal intervention; fees based on the 10th percentile general practice fees), highest possible cost (maximum intervention; fees based on the 90th percentile general practice fees), and midrange cost (an average of the fees
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Fig 2. Clinical procedures used in cost analysis.
for maximum and minimum intervention; based on the mean general practice fees). If procedure codes were not listed in the fee survey, costs were estimated by using similar procedure codes with known local and American Dental Association fees. Trauma present at the initial evaluation was not included. The expected cost of incisor trauma per child during the trial was calculated by multiplying the possible cost of treatment for each trauma category by the frequency with which each trauma category occurred and then summing the results for all 7 trauma categories. The expected cost gives a comparison of the costs that might result from increased trauma if orthodontic treatment were begun in the mixed dentition or delayed until the permanent dentition.
RESULTS
Of the 179 patients (105 boys; 74 girls) who had initial records, 163 with complete trauma data (61, observation only; 52, functional appliance; and 50, headgear) completed phase 1 of the trial. During phase 2, 139 of these patients started and completed comprehensive treatment with fixed appliances (51, control; 42, functional appliance; and 46, headgear). At baseline, only 3 patients from the group had trauma to the mandibular incisors, and 1 patient had trauma to both the mandibular and maxillary incisors. The number of patients with maxillary incisor trauma was significantly greater than the number with mandibular incisor trauma (P ⬍ .001, McNemar test). Because
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Table I. Prevalence of traumatized maxillary incisors at baseline clinical evaluation
Trauma category 1 and 2 Craze lines; enamel only 3 Enamel and dentine 5 Restored fracture Total
Prevalence of traumatized maxillary incisors by dental age at baseline (before phase 1)
Table II.
Right Right Left Left lateral central central lateral Patients 2
21
18
4
37
0
1
0
0
1
1
8
10
0
15
3
30*
28*
4
53
Dental age
n
Number of patients with trauma
⬍9 9-9.9 10-10.9 ⱖ11
33 59 43 43
9 20 11 12
Percentage of dental age group with trauma*
Number of patients with trauma in ⬎1 tooth
27.3 33.9 25.6 27.9
2 0 4 3
n ⫽ 179 (105 males; 74 females). *Maxillary central incisors (58) had significantly more trauma than maxillary lateral incisors (7) (P ⬍ .001, McNemar test).
Total n ⫽ 178; mean dental age, 10.03 ⫾ 1.25 years (SD). Unable to determine dental age of 1 patient because of the lack of baseline panoramic radiograph. *No significant difference (P ⫽ .84, Fisher exact test).
mandibular trauma was so infrequent, only new maxillary incisor trauma was reported in this study. The prevalence of traumatized maxillary incisors and the number of patients with maxillary incisor trauma at baseline are shown in Table I. Forty-seven patients had maxillary central incisor trauma, 4 had maxillary lateral incisor trauma, and 2 had both maxillary central and lateral incisor trauma. The number of patients with maxillary central incisor trauma was significantly greater than patients with maxillary lateral incisor trauma (P ⬍ .001, McNemar test). At the start of the trial, there was no significant difference in the proportion of patients with and without maxillary incisor trauma by sex (P ⫽ .41, Fisher exact test) or by early treatment group (P ⫽ .08, Fisher exact test). Furthermore, the extent (number of maxillary teeth with trauma per child) (P ⫽ .31, Mantel Haenszel row mean score) and severity (sum of the trauma scores for each child) (P ⫽ .74, Mantel Haenszel row mean score) of trauma were not significantly different among the 3 groups. Because the children’s incisors might have been erupted for different lengths of time before the study, the prevalence of traumatized maxillary incisors at the time of initial records is shown in Table II by dental developmental age. No significant difference was found in the proportion of patients with and without maxillary incisor trauma among the 4 dental age categories (P ⫽ .84, Fisher exact test). The proportion of patients with trauma remained relatively stable throughout the late mixed and early permanent dentition. The incidence of new maxillary incisor trauma during phase 1 of the trial is shown in Table III. During the first phase of the trial, 16 patients sustained new trauma to 17 teeth. Within the groups, this change in incisor trauma was statistically different from 0 for both the control and the headgear groups, but not for the
functional appliance group, although the incidence in this group was only slightly smaller than that of the other groups. However, among the 3 early treatment groups, there was no statistically significant difference in the proportion of patients with and without new maxillary incisor trauma. This apparent lack of difference in the magnitude of the change among the 3 groups might be a function of the relatively small samples considered. The new trauma was generally minor; only 3 teeth required resin restorations. There was no significant difference in new maxillary incisor trauma between boys and girls during phase 1(P ⫽ .27, Fisher exact test). Additional incisor trauma also occurred in the second phase of the trial during comprehensive orthodontic treatment and is shown in Table IV. During this phase, 21 patients sustained new trauma to their maxillary incisors. This change in incisor trauma was statistically different from 0 for the control group, but not for the headgear and the functional appliance groups. Again, there was no significant difference in the proportion of patients with and without new maxillary incisor trauma among the 3 early treatment groups. As in phase 1, most new injuries tended to result in craze lines or enamel-only fractures. Only 1 patient required a resin restoration; another patient required endodontic treatment of a maxillary central incisor that had evidence of craze lines at the end of phase 1. There was no significant difference in new maxillary incisor trauma between boys and girls during phase 2 of the trial (P ⫽ .35, Fisher exact test). At baseline records, there was no significant difference between the mean overjet of patients with maxillary incisor trauma (9.50 ⫾ 2.28 mm, mean ⫾ SD) and patients without maxillary incisor trauma (9.22 ⫾ 1.89 mm) (P ⫽ .42, unpaired t test). There was a statistically significant difference in the mean overjet change
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Table III.
New maxillary incisor trauma during phase 1 Control* (n ⫽ 61)
Trauma category 1 and 2 Craze lines; enamel only 3 Enamel and dentine 5 Restored fracture Total
Functional* (n ⫽ 52)
Headgear* (n ⫽ 50)
Laterals
Centrals
Patients
Laterals
Centrals
Patients
Laterals
Centrals
Patients
0
7
7
0
3
3
0
4
3
0
0
0
0
0
0
0
0
0
0
2
2
0
0
0
0
1
1
0
9
9
0
3
3
0
5
4
*No significant difference in proportion of patients with and without new maxillary incisor trauma (P ⫽ .29 Fisher exact test). Statistically significant increase in presence of maxillary incisor trauma in control group (P ⫽ .002) and headgear group (P ⫽ .03) but not functional appliance group (P ⫽ .13) (McNemar 1-tailed test). Table IV.
New maxillary incisor trauma during phase 2 Control* (n ⫽ 51)
Trauma category 1 and 2 Craze lines; enamel only 3 Enamel and dentine 5 Restored fracture Total
Functional* (n ⫽ 42)
Headgear* (n ⫽ 46)
Laterals
Centrals
Patients
Laterals
Centrals
Patients
Laterals
Centrals
Patients
3
11
11
5
3
5
0
6
4
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
12
12
5
3
5
0
6
4
*No significant difference in proportion of patients with and without new maxillary incisor trauma (P ⫽ .12, Fisher exact test). Statistically significant increase in presence of maxillary incisor trauma in control group (P ⫽ .004) but not headgear group (P ⫽ .06) or functional appliance group (P ⫽ .19) (McNemar 1-tailed test) during phase 2. One additional control patient required endodontic treatment of maxillary right central incisor (end of phase 1 score of 1 [enamel fracture] to end of phase 2 score of 6 [lingual restoration indicative of endodontic access]).
among the 3 groups during both phase 1 (P ⫽ .0001, 1-way analysis of variance [ANOVA]) and phase 2 (P ⫽ .0001, 1-way ANOVA) (Fig 3). Table V shows the probability of each trauma category that occurred during phases 1 and 2 of the trial and the range of fees associated with each trauma category. The expected cost of trauma per patient in the control and the treatment groups during the entire trial is shown in Table VI. DISCUSSION
Even minor dental trauma can lead to significant complications despite appropriate initial treatment.12-15 The prognosis for traumatized teeth can be guarded for a long time after the initial injury. A rational approach to dental trauma would be to prevent or reduce these injuries rather than to treat the resulting significant immediate and long-term sequelae. The prevalence of recorded dental trauma has varied from 4% to 30% of children in previous studies.15 This clinical trial confirmed findings that the
incidence of incisor trauma in children with Class II malocclusion is high.1-3 A significant amount of incisor trauma occurred before the start of the trial; approximately one-third of the children with a dental age of less than 9 years had incisor trauma at the start of the trial. A more accurate determination of the time of initial incisor trauma would require a longitudinal study of a larger group of younger children enrolled at the dental age of 5 or 6 years. These age-related findings are similar to those of a longitudinal study of Danish children from birth to 14 years of age, in which 30% of them sustained injuries to the deciduous dentition, and 22% had injuries to the permanent dentition.16 The incidence of dental trauma has been shown to increase between 2 and 4 years of age in the deciduous dentition for boys and girls and between 8 and 10 years of age in the permanent dentition for boys.16,17 In this study, the prevalence of incisor trauma by dental developmental age rather than chronological age was shown at baseline records before phase 1 treatment as a proxy measure for the length of
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Fig 3. Change in overjet during phases 1 and 2.
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Table V.
Probability of additional trauma during entire trial and ranges of possible fees for trauma categories Probability of trauma during entire trial
Range of fees for trauma categories ($)
Trauma category
Control
Functional
Headgear
Low
Mid
High
1 2 3 5 6
0.0392 0.2912 0.0196 0.0327 0.0196
0.0476 0.1291 0 0 0
0.0434 0.1035 0 0.0200 0
0.00 0.00 107.00 107.00 382.00
67.15 117.04 234.08 234.08 640.51
194.00 334.00 443.00 443.00 1000.00
163 patients completed phase 1; 139 patients completed phase 2. Probability (entire trial) ⫽ probability (phase 1) ⫹ probability (phase 2).
Expected cost of trauma for patients who received early treatment with headgear and functional appliance compared with treatment delayed until permanent dentition
Table VI.
Expected cost range ($) Group
Low
Mid
High
Control Functional Headgear
13.10 0.00 2.14
60.56 18.31 19.70
147.70 52.03 51.85
Expected Cost ⫽ ⌺ (probability of trauma category) ⫻ (estimated fee for trauma category) for low, mid, and high ranges. For example, expected cost (low range) for control group (from Table V) ⫽ (0.0392)(0.00) ⫹ (0.2912)(0.00) ⫹ (0.0196)(107.00) ⫹ (0.0327)(107.00) ⫹ (0.0196)(382.00) ⫽ 13.10.
time the incisors had been erupted. The implications of the relationship between incisor trauma and the age of occurrence are crucial to the discussion of the efficacy of early orthodontic correction of severe overjet to reduce the risk of incisor trauma. The proportion of patients with maxillary incisor trauma at baseline records was not significantly different among the 4 dental developmental age categories, tempting one to conclude that a significant amount of the maxillary incisor trauma does occur early, shortly after the permanent incisors erupt. Thus, if early treatment is planned to prevent incisor trauma, it should be undertaken soon after these teeth erupt. However, the risks and costs of this approach must also be considered. In this study, the proportion of patients with and without maxillary incisor trauma at the time of baseline records was not significantly different between boys and girls. This is contrary to other findings, which have generally suggested an increased prevalence of incisor trauma in boys,18-20 but similar to those of GarciaGodoy et al.21 As in previous studies, the susceptibility of teeth to trauma was related to their position in the dental
arches.22 The maxillary incisors were found to have a much higher prevalence and incidence of trauma than the mandibular incisors, and the maxillary central incisors had a higher prevalence and incidence of trauma than did the maxillary lateral incisors. A high proportion of these patients incurred damage to their incisors before and during this investigation. However, most trauma was minor, consisting of enamel fractures and craze lines with good long-term prognoses.13,15 Improvements in resin bonding materials and techniques have greatly simplified the way clinicians treat minor incisor trauma. During the trial, only 1 tooth received trauma severe enough to require endodontic treatment. The main objective of the trial was to assess the possibility of growth changes during early treatment for Class II malocclusion, not to assess the benefit of early correction of overjet. In addition, the headgear and functional appliances used during the first phase of the trial produced different incisor effects. The functional appliance, although designed to prevent tipping, tended to have a direct effect on the maxillary incisors; this resulted in a significantly greater reduction of overjet during phase 1 compared with the headgear and the control groups, in which most overjet correction was completed during phase 2. During phase 1, the incidence of incisor trauma was statistically significant in the control and headgear groups, but not in the functional appliance group. During phase 2, the incidence of incisor trauma was statistically significant in the control group but not in the functional appliance or the headgear groups. The difference in the incidence of trauma was not significantly different between the groups during phases 1 and 2. During phase 1, without treatment, the control group experienced the largest increase in incisor trauma and only minor reduction in overjet, whereas the functional appliance group experienced less new maxillary incisor trauma and had the largest reduction in overjet. These
124 Koroluk, Tulloch, and Phillips
findings might suggest that early orthodontic treatment specifically designed to reduce overjet can affect the incidence of maxillary incisor trauma in children. In patients with increased overjet due to maxillary dentoalveolar protrusion, early orthodontic treatment with a 2 ⫻ 4 appliance or Hawley appliance with an active labial bow can be started shortly after the eruption of the central incisors at approximately age 7 years to reduce overjet. This early treatment would not necessarily be considered a growth modification phase if the increased overjet was dentoalveolar. A clinical trial would have to be designed to test the effectiveness of such early dentoalveolar intervention in preventing future early incisor trauma. Considering the costs of treating trauma, a wide range of estimates for the additional associated treatment costs has been presented. Combining cost data with the likelihood of a child sustaining different types of trauma suggests that the expected costs (cost of treating trauma ⫻ probability of trauma) are very similar for the 2 early treatment groups and higher for the patients receiving no early treatment, whether the low, medium, or high estimated costs are used. However, this increase in expected costs must be balanced with the almost certain increased cost of 2-stage orthodontic treatment. For most patients in this study, the cost of restoring the damaged incisors was minor compared with the increased fees generally associated with 2-phase early orthodontic treatment. A significant proportion of the high-range cost per child was related to extensive treatment for enamel fractures that might more realistically receive enamoplasty or no treatment at all. The low to midrange cost per child appears to be a more clinically realistic representation of the true cost of trauma per patient. Indeed, in this trial, most injuries were minor and easily treated at low cost with good long-term prognosis. Cost calculations were structured to reflect the relative short-term costs of incisor trauma, but all restorations have a real clinical life span. Larger category 3 and 5 fractures might require future replacement with more expensive veneers or crowns, thus increasing the expected cost. There were a minimal number of category 3 and 5 fractures that might require further long-term treatment; therefore, these costs were not included in the model because these small frequencies would not significantly affect the results of the analysis. Also, the life span of bonded resins has increased significantly with the advent of new bonding materials and techniques. From a public health perspective, the feasibility of early orthodontic treatment as a policy to reduce the incidence of trauma in all children with overjets greater
American Journal of Orthodontics and Dentofacial Orthopedics February 2003
than 7 mm would be financially prohibitive, because the orthodontic intervention would have to be very early and almost certainly followed by a second phase of treatment, and it would cost much more than the treatment of any possible incisor trauma. However, for an individual patient, the choices are more complex. Parents might elect early orthodontic treatment that reduces overjet to possibly decrease the likelihood of major incisor trauma and future trauma-related expenses. Nondental variables such as risk-taking behavior and increased physical activity can also place children at risk for incisor trauma regardless of the position of the incisors. Although all the children in this study had overjets greater than 7 mm, they did not have similar incisor trauma experiences. It is possible that a threshold overjet might exist, above which a child has an increased risk of incisor trauma. Other social and behavioral factors might place a susceptible child in the right environment to ultimately traumatize the teeth. The sample followed here was of insufficient size to permit such subgroup analysis. Only simple bivariate statistical analysis was used on the data from this clinical trial because the relative sample sizes of patients with and without trauma precluded using logistic regression analysis. As a result, the combination effect of multiple variables might be significant (ie, dental or chronologic age combined with sex), whereas the individual variables alone show no association with trauma. Although data analysis is not yet complete, the oral health, measured as periodontal indexes and enamel lesions, of children who had early treatment in this trial does not appear dissimilar from those for whom orthodontic treatment was delayed until their permanent dentition. Currently, another project is underway to evaluate whether teeth that have sustained trauma are at greater risk of root resorption than those that have not. CONCLUSIONS
The following conclusions can be made from this study of orthodontic treatment in preadolescent patients with Class II Division 1 malocclusions: 1. A significant number of patients had trauma to the maxillary incisors, but the injuries were minor. Most of the new injuries were minor and could easily be treated at low cost and with good long-term prognoses. 2. Early growth modification treatment might have some effect on the incidence of trauma, but to be effective it might have to be initiated soon after the eruption of the maxillary incisors. 3. The expected cost of trauma per child was less for
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patients who had early growth modification treatment than for patients whose treatment was delayed until their permanent dentition, but this expected difference must be balanced with the usually greatly increased cost of 2-phase early orthodontic treatment. REFERENCES 1. Dearing SG. Overbite, overjet, lip-drape and incisor tooth fracture in children. NZ Dent J 1984;80:50-2. 2. Ghose LJ, Baghdady VS, Enke H. Relation of traumatized permanent anterior teeth to occlusion and lip condition. Community Dent Oral Epidemiol 1980;8:381-4. 3. O’Mullane DM. Some factors predisposing to injuries of permanent incisors in school children. Br Dent J 1973;134:328-32. 4. King GJ, Keeling SD, Hocevar RA, Wheeler TT. The timing of treatment for Class II malocclusion in children: a literature review. Angle Orthod 1990;60:87-97. 5. Tulloch JFC, Phillips C, Koch G, Proffit WR. The effect of early intervention on skeletal pattern in Class II malocclusion: a randomized clinical trial. Am J Orthod Dentofacial Orthop 1997;111:391-400. 6. Tulloch JFC, Proffit WR, Phillips C. Influences on the outcome of early treatment for Class II malocclusion. Am J Orthod Dentofacial Orthop 1997;111:533-42. 7. Tulloch JFC, Phillips C, Proffit WR. Benefit of early Class II treatment: progress report of a two-phase randomized clinical trail. Am J Orthod Dentofacial Orthop 1998;113:62-72. 8. National Center for Health Statistics. NHANES III dental examiner’s manual. Hyattsville (Md): Westat, Inc; 1992. 9. Demirjiam A, Goldstein H, Tanner JM. A new system of dental age assessment. Hum Biol 1973;45:211-27. 10. American Dental Association. The 1999 survey of dental fees. Chicago: American Dental Association Survey Center; 1999. 11. Andreasen JO, Andreasen FM. Essentials of traumatic injuries to the teeth. Copenhagen: Munksgaard; 1990. p. 11-45. 12. Andreasen FM, Pedersen BV. Prognosis of luxated permanent teeth—the development of pulp necrosis. Endod Dent Traumatol 1985;1:207-20. 13. Zadik D, Chosack A, Eidelman E. The prognosis of traumatized permanent anterior teeth with fracture of enamel and dentin. Oral Surg Oral Med Oral Pathol 1979;47:173-5. 14. Hedegard B, Stalhane I. A study of traumatized permanent teeth in children aged 7-15 years. Swed Dent J 1973;66:431-50. 15. Andreasen JO. Traumatic injuries of the teeth. 2nd ed. Copenhagen: Munksgaard; 1981. p. 40, 78, 227. 16. Andreasen JO, Ravn JJ. Epidemiology of traumatic dental injuries to primary and permanent teeth in a Danish population sample. Int J Oral Surg 1972;1:235-9. 17. Mullane DM. Injured permanent incisor teeth: an epidemiological study. J Ir Dent Assoc 1972;18:160-73. 18. Kaste LM, Gift HC, Bhat M, Swango PA. Prevalence of incisor trauma in persons 6-50 years of age: United States, 1988-1991. J Dent Res 1996;75:696-705. 19. Kania MJ, Keeling SD, McGorray SP, Wheeler TT, King GJ. Risk factors associated with incisor injury in elementary school children. Angle Orthod 1996;66:423-32. 20. Ravn JJ. Dental injuries in Copenhagen schoolchildren, school years 1967-1972. Community Dent Oral Epidemiol 1974;2:23145. 21. Garcia-Godoy F, Sanchez R, Sanchez J. Traumatic dental inju-
ries in a sample of Dominican school children. Community Dent Oral Epidemiol 1981;9:193-217. 22. Gutz DP. Fractured permanent incisors in a clinic population. J Dent Child 1971;38:94-121.
COMMENTARY
A quick MEDLINE search for overjet, incisor trauma, and Class II malocclusion yields a list of more than 100 references. Obviously, the subject is both of considerable interest to the dental profession and well studied. So why would the American Journal of Orthodontics and Dentofacial Orthopedics want to publish yet another article on this subject? Any new work on the topic must offer more than an epidemiologic look at the incidence and prevalence of incisor trauma among children, and this article does. When an orthodontist recommends an early phase of treatment, there should be clear benefits for the consumer. These benefits might include increased stability, reduced treatment time in the second phase, reduced risk of future problems, or reduced costs. The epidemiologic data indicate that children with excessive overjet are more prone to incisor trauma, and an orthodontist might recommend early treatment to reduce the excessive overjet and to minimize the risk of incisor trauma. On the other hand, there is a trend toward delaying the correction of the Class II malocclusion until the late mixed dentition period. Prospective studies, including those from the University of North Carolina, do not make a strong argument for an early phase of orthopedic treatment to reduce a Class II malocclusion. However, is reducing incisor overjet a benefit of early treatment that we can “hang our hat on”? This article is based on a sample from a University of North Carolina prospective study on the efficacy of early Class II correction with either bionator functional appliance or headgear versus no early treatment. Both groups were treated with fixed appliances later. The prevalence, extent, and severity of incisor trauma were recorded for all 3 groups at baseline, and they were evaluated 15 months later to compare the incidence of new incisor trauma. Finally, the costs and risks of increased incisor trauma were compared for each group. At baseline, 29.6% of the patients already had trauma to at least 1 incisor. Of these, 8.4% already had restorations. Most of the others had only craze lines or enamel fractures. During the next 15 months of phase I treatment (or observation of the untreated control group), 9.8% of the patients had new fractures of at least 1 incisor. The majority were simple craze lines or enamel fractures. Interestingly, these were greater in
126 Koroluk, Tulloch, and Phillips
the control and the headgear groups than in the bionator group. The authors attribute this to the uprighting of the maxillary incisors from the labial bow of the bionator. During phase II treatment with fixed appliances, an additional 15.1% of the patients experienced a new fracture of at least 1 incisor. Nearly all of these were craze lines or simple enamel fractures. The authors calculated the expected cost of new incisor trauma as the probability of trauma for each group multiplied by the estimated fee for the treatment. Using the midrange of fees, the authors calculated the cost for the control group at $60.56, whereas the costs for the bionator and the headgear groups were $18.31 and $19.70, respectively; obviously, these amounts are less than the fees most orthodontists would assess for a first phase of treatment. A major shortcoming of this article is the timing of the onset of treatment. The youngest patient in this sample was 7.9 years old, and the mean chronological age was 9.83 years. By then, 29.6% of the sample had some form of trauma to at least 1 of their incisors. If our objective is to treat early to reduce incisor trauma, then we should screen these patients, as the American Association of Orthodontists suggests, closer to age 7 (or earlier). We then should ask what we can do if we see them just after the eruption of the maxillary incisors. Is the overjet caused by maxillary dentoalveolar protrusion or mandibular retrognathia? If dental, will we use fixed or removable appliances to upright maxillary incisors that might not have completely formed roots? If skeletal, will we treat the mandibular retrognathia at age 6 or 7 years? If our treatment philosophy is to treat Class II skeletal problems in the late mixed dentition, would a mouthguard, as recommended by the American Association of Orthodontists, have a significant benefit? Epidemiologic samples tend to be large— often over 1000 —in studies examining incisor trauma and ovejet. The current sample is small by comparison, and some findings might differ because of the sample size.
American Journal of Orthodontics and Dentofacial Orthopedics February 2003
For example, many epidemiologic studies show that incisor trauma is more prevalent in boys than in girls. This was not a finding of the present study. The statistical analyses, however, were quite specific and appeared to address this shortcoming. This is not just another article on incisor trauma and overjet. The authors have carefully reaped useful information from a well-documented sample to add another piece to the puzzle of the benefits of early orthopedic treatment. They have also humbly and thoroughly recognized the shortcomings of this sample in predicting the efficacy of early treatment in reducing incisor trauma. They suggest a future clinical trial to look at a younger sample. Tomorrow, will I stop doing early treatment to correct Class II skeletal problems because of this study? No, because many of my Class II skeletal patients also have associated vertical and transverse skeletal problems, making predictable correction in the late mixed dentition too complex. No, because many young girls who have severe Class II skeletal problems also have delayed dental development and are early skeletal maturers; surgical correction or compensation would be the only options if treatment were delayed until the late mixed dentition. No, because my 8- and 9-year-old patients typically cooperate better with removable functional appliance and headgear treatment than my 11and 12-year-old patients. No, because some patients are self-conscious about their excessive overjet and lip incompetency, and some have speech difficulties, and their parents are concerned. On the other hand, tomorrow will I look at these patients a little differently because of this study? I most certainly will. Gary R. Wolf, DDS, MSD Norwalk, Ohio Copyright © 2003 by the American Association of Orthodontists. 0889-5406/2003/$30.00 ⫹ 0 doi:10.1067/mod.2003.92