- Email: [email protected]
Stability and relapse of maxillary anterior crowding treatment in Class I and Class II Division 1 malocclusions
ORIGINAL ARTICLE
Stability and relapse of maxillary anterior crowding treatment in Class I and Class II Division 1 malocclusions Camila Leite Quaglio,a Karina Maria Salvatore de Freitas,b Marcos Roberto de Freitas,c Guilherme Janson,c Fernando Castanha Henriquesc and Jose Bauru, S~ao Paulo, Brazil Introduction: The maxillary anterior teeth are the most important to facial esthetics because they are the first to show on a smile. Therefore, stability of the maxillary anterior teeth alignment is an important issue. The objective of this study was to compare the stability of maxillary anterior tooth alignment in Class I and Class II Division 1 malocclusions. Methods: The sample comprised dental casts of 70 patients with Class I and Class II Division 1 malocclusions and a minimum of 3 mm of maxillary anterior crowding measured by an irregularity index. The patients were treated with extractions and evaluated at pretreatment and posttreatment and at least 5 years after treatment. The sample was divided into 3 groups: group 1, Class I malocclusion treated with 4 first premolar extractions comprising 30 subjects, with an initial age of 13.16 years and 8.59 mm of initial maxillary irregularity; group 2, Class II malocclusion treated with 4 first premolar extractions comprising 20 subjects, with an initial age of 12.95 years and 11.10 mm of maxillary irregularity; and group 3, Class II malocclusion treated with 2 first maxillary premolar extractions comprising 20 subjects, with an initial age of 13.09 years and 9.68 mm of maxillary irregularity. Results: The decrease in the maxillary irregularity index was significantly greater in group 2 than in group 1 during treatment. The stability of maxillary anterior alignment was 88.12% over the long term; 77% of the linear displacement of the anatomic contact points tended to return to their original positions. Conclusions: Stability of maxillary anterior alignment between the 3 groups was similar. The stability of maxillary anterior alignment was high over the long term, but a high percentage of teeth tended to return to their original positions. (Am J Orthod Dentofacial Orthop 2011;139:768-74)
E
sthetic treatments are common nowadays because concern with facial appearance has greatly increased in the last decades. Alignment of the maxillary anterior teeth is especially important for an esthetic smile, since they are the first to show. Many patients seek orthodontic treatment to align these teeth. Correct orthodontic treatment improves facial esthetics as well as the occlusion, but long-term stability of the aligned teeth is highly variable and unpredictable. Greater research emphasis has been placed on relapse of mandibular anterior crowding probably because a Orthodontic graduate student, Department of Orthodontics, Bauru Dental School, University of S~ao Paulo, Bauru, S~ao Paulo, Brazil. b and UNORP. Professor of UNINGA c Professor and head, Department of Orthodontics, Bauru Dental School, University of S~ao Paulo, Bauru, S~ao Paulo, Brazil. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Camila Leite Quaglio, Rua Visconde de Castro, 573, S~ao Paulo, SP, 04611-050, Brazil; e-mail, [email protected]. Submitted, April 2009; revised and accepted, October 2009. 0889-5406/$36.00 Copyright Ó 2011 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2009.10.044
768
alignment stability of these teeth is less than that of the maxillary anterior teeth.1-4 Nevertheless, little emphasis has been given to investigating the direction of relapse.4,5 Patients tend to judge orthodontic treatment success primarily by maxillary anterior tooth alignment.5-8 Therefore, long-term stability investigations of maxillary anterior tooth alignment have become important in orthodontics. Because of insufficient studies on maxillary anterior tooth alignment, the objectives of this investigation were to evaluate the amount and direction of relapse of maxillary anterior crowding in different extraction protocols, compare the relapse amounts in Class I and Class II Division 1 malocclusions, and evaluate possible relationships between crowding relapse and intercanine, interpremolar, and intermolar widths, arch lengths, and amounts of initial maxillary anterior crowding. MATERIAL AND METHODS
The sample was retrospectively selected from over 4500 patient records treated by graduate students in the Department of Orthodontics at Bauru Dental School,
Quaglio et al
University of S~ao Paulo, Brazil. The selection criteria were patients under 15 years of age at pretreatment (T1), with all permanent teeth erupted up to the first molars; no supernumerary teeth or tooth agenesis; Class I or Class II Division 1 malocclusion of at least three-quarter cusp Class II molar relationship; and more than 3 mm of crowding on Little’s irregularity index9 in the mandible (LIIMx). The patients also had a maximum peer assessment rating (PAR) score of 5 at posttreatment (T2), and balanced faces and passive lip seal. Subjects with anterior open bite or crossbite malocclusion were not included. Therefore, the sample comprised 70 patients divided into 3 groups, evaluated at 3 stages: T1, T2, and postretention (T3). Thirty had Class I and 40 had Class II Division 1 malocclusions (5 had three-quarter cusp, and 65 had full-cusp Class II molar relationships). Group 1 comprised 30 patients (12 boys, 18 girls) with Class I malocclusion treated with 4 first premolar extractions. Mean initial maxillary anterior crowding, initial age, and treatment time were 8.59 mm (SD, 3.08), 13.16 years (SD, 0.97), and 1.99 years (SD, 0.51), respectively. Group 2 consisted of 20 patients (11 boys, 9 girls) with Class II Division 1 malocclusion treated with 4 first premolar extractions. Mean initial maxillary anterior crowding, initial age, and treatment time were 11.10 mm (SD, 4.46), 12.95 years (SD, 1.08), and 2.48 years (SD, 0.72), respectively. Group 3 comprised 20 patients (9 boys, 11 girls) with Class II Division 1 malocclusions treated with 2 maxillary first premolar extractions. Mean initial maxillary anterior crowding, initial age, and treatment time were 9.68 mm (SD, 4.00), 13.09 years (SD, 1.11), and 2.05 years (SD, 0.45), respectively. All patients were treated with fixed edgewise appliances. Anterior retraction was performed by sliding mechanics with elastic chains. All patients used an extraoral appliance for anchorage reinforcement, as needed, during active treatment. No patient underwent interproximal stripping, rapid maxillary expansion, or fiberotomy as part of the treatment plan. Class II elastics were used when necessary, especially in the Class II malocclusion patients treated with 4 maxillary premolar extractions. Retention included a maxillary Hawley plate and a bonded lingual canine-to-canine retainer in the mandibular arch. The assessed variables consisted of LIIMx, arch length (AL), intercanine width (ICW), interpremolar width (IPW), and intermolar width (IMW) (Figs 1 and 2). All dental cast measurements were made with a 0.01-mm precision digital caliper (Mitutoyo America, Aurora, Ill) by the same examiner (C.L.Q.). To investigate the direction of relapse, each linear displacement of the anatomic contact points was
769
Fig 1. Little’s irregularity index in the maxillary arch.
Fig 2. A 1 B 5 arch length; C 5 intercanine width; D 5 interpremolar width; E 5 intermolar width.
separately evaluated at T1 and T3 in the maxillary arch.9 The contact points (A, B, C, D, and E) were evaluated by taking into account the direction of each anterior tooth in relation to its adjacent tooth (labial or lingual). The relapse percentage was calculated as the ratio between the relapse and the correction amounts. To analyze whether the percentage of relapse was associated with the amount of initial crowding, the whole sample was divided into 2 subgroups according to initial crowding. Subgroup A comprised patients with LIIMx scores less than 7 mm, or minimal and moderate irregularity (19 patients), and subgroup B had LIIMx scores equal to or greater than 7 mm, or severe and very severe irregularity (51 patients).9 A month after the first measurements, randomly selected dental casts of 15 patients (21% of the whole
American Journal of Orthodontics and Dentofacial Orthopedics
June 2011 Vol 139 Issue 6
Quaglio et al
770
sample) were remeasured by the same examiner (C.L.Q.) in all stages (T1, T2, and T3). Casual errors were P calculated according to Dahlberg’s formula (SE2 5 d2 =2n),10 where SE2 is the error variance and d is the difference between 2 determinations of the same variable. Systematic errors were evaluated with dependent t tests at P \0.05. Statistical analysis
Normal distribution was verified by the KolmogorovSmirnov test. The results were nonsignificant for all variables. Intergroup sex distribution was evaluated with the chi-square test; intergroup comparisons of age, treatment, retention, posttreatment, and postretention observation times, and initial and final LIIMx scores were made with 1-way analysis of variance (ANOVA), followed by Tukey tests when necessary. These last tests were also used to evaluate intergroup comparisons of LIIMx scores, AL, and ICW, IPW, and IMW at T1, T2, and T3, and their treatment (T2-T1) and posttreatment (T3-T2) changes. Pearson correlation coefficients were used to assess the relationships of LIIMx scores at different stages with the other variables, and the relationships between linear displacements of the anatomic contact points at T1 and T3. The percentages of teeth that kept the same labiolingual direction at T1 and T3 were calculated. The relapse percentages in subgroups A and B were compared with t tests. All statistical analyses were performed with Statistica software (version 6.0, Statsoft, Tulsa, Okla), and the results were considered significant at P \0.05.
Table I. Casual and systematic errors between the first and second measurements (mm) Measurement 1 Measurement 2 Variable A at T1 B at T1 C at T1 D at T1 E at T1 LIIMx at T1 AL at T1 ICW at T1 IPW at T1 IMW at T1 A at T2 B at T2 C at T2 D at T2 E at T2 LIIMx at T2 AL at T2 ICW at T2 IPW at T2 IMW at T2 A at T3 B at T3 C at T3 D at T3 E at T3 LIIMx at T3 AL at T3 ICW at T3 IPW at T3 IMW at T3
Mean 2.67 2.10 1.10 1.08 2.58 9.52 72.24 35.04 37.28 48.84 0.05 0.18 0.09 0.16 0.20 0.69 62.68 34.69 36.64 48.50 0.25 0.32 0.31 0.38 0.42 1.69 61.48 34.65 35.62 47.62
SD 1.55 1.29 1.19 0.93 1.89 4.29 4.35 1.72 1.92 2.61 0.10 0.29 0.15 0.25 0.25 0.48 2.46 1.81 2.08 2.92 0.40 0.36 0.36 0.45 0.65 1.47 2.22 1.70 2.33 3.28
Mean 2.66 2.08 1.08 1.05 2.53 9.40 72.26 34.91 37.39 48.87 0.05 0.19 0.06 0.10 0.18 0.58 62.75 34.77 36.61 48.56 0.22 0.32 0.26 0.31 0.36 1.47 61.38 34.65 35.72 47.63
SD 1.52 1.25 1.11 0.92 1.87 4.16 4.24 1.88 1.97 2.56 0.07 0.22 0.10 0.18 0.24 0.30 2.36 1.72 2.03 2.80 0.34 0.35 0.27 0.37 0.63 1.23 2.40 1.75 2.21 3.23
Dahlberg 0.127 0.118 0.106 0.059 0.083 0.286 0.616 0.436 0.232 0.197 0.034 0.116 0.047 0.078 0.065 0.182 0.574 0.192 0.160 0.169 0.085 0.081 0.086 0.113 0.152 0.069 0.960 0.151 0.472 0.991
P 0.848 0.779 0.635 0.181 0.147 0.285 0.955 0.431 0.222 0.705 0.608 0.964 0.098 0.034* 0.424 0.091 0.737 0.265 0.671 0.333 0.275 0.813 0.104 0.081 0.152 0.069 0.961 0.151 0.472 0.991
*Statistically significant at P \0.05.
RESULTS
No variable showed a casual error greater than 1 mm. Among 30 variables, only width D at T2 showed a statistically significant systematic error (Table I). The groups were compatible regarding all variables, except that group 2 had a significantly longer treatment time than group 1 (Tables II and III). Decreases in the LIIMx scores were significantly greater in group 2 than in group 1 during treatment. The increase in IPW was significantly greater in group 2 than in groups 1 and 3, in which it decreased during treatment. IMW at T2 was significantly smaller in group 3 than in group 2. The decrease in IMW was significantly greater in group 3 than in group 2 during treatment (Table IV). There were positive significant correlations between the T1 and the T3 LIIMx scores, between the T1 LIIMx score and the relapse at T3, and between the T2 and T3 LIIMx scores (Table V). There were significant positive correlations between linear displacements of anatomic contact points B, C,
June 2011 Vol 139 Issue 6
Table II. Intergroup comparison of sex distribution
(chi-square test)
Sex Male Female Total
Group 1, Class I, 4 extractions 12 18 30
Group 2, Class II Division 1, 4 extractions 11 9 20
Group 3, Class II Division 1, 2 extractions 11 9 20
Total 34 36 70
Chi-square 51.544; df 5 2; P 5 0.462.
and D at T1 and T3 (Table V), and 77% of the linear displacements of the anatomic contact points had the same direction at T1 and T3. There was no significant difference between subgroups A and B regarding the relapse percentages (Table VI). DISCUSSION
The sample was selected by previously described valid inclusion criteria and according to the objectives of the
American Journal of Orthodontics and Dentofacial Orthopedics
Quaglio et al
771
Table III. Intergroup comparisons of age, treatment, retention, posttreatment and postretention observation times,
initial and final LIIMx scores (ANOVA followed by Tukey tests) Group 1, Class I, 4 extractions Variable T1 age (y) T2 age (y) T3 age (y) Treatment time (y) Retention time (y) T2 observation (y) T3 observation (y) LIIMx at T1 (mm) LIIMx at T2 (mm)
Mean 13.16A 15.15A 23.71A 1.99A 1.24A 8.55A 7.31A 8.59A 0.80A
SD 0.97 1.14 2.80 0.51 0.53 3.03 3.18 3.08 0.90
Group 2, Class II Division 1, 4 extractions Mean 12.95A 15.43A 24.97A 2.48B 1.28A 9.54A 8.26A 11.10A 0.61A
SD 1.08 1.28 4.02 0.72 0.54 4.27 4.47 4.46 0.52
Group 3, Class II Division 1, 2 extractions Mean 13.09A 15.14A 25.02A 2.05AB 1.10A 9.88A 8.78A 9.68A 0.64A
SD 1.11 1.10 2.85 0.45 0.27 2.87 2.95 4.00 0.55
P 0.760 0.604 0.159 0.01* 0.419 0.209 0.191 0.077 0.601
Different letters indicate statistically significant differences. *Statistically significant at P \0.05.
Table IV. Intergroup comparisons (mm) of LIIMx scores, AL, ICW, IPW, and IMW at T1, T2, and T3, and their treatment (T2-T1) and posttreatment (T3-T2) changes (1-way ANOVA followed by Tukey tests) Group 1, Class I, 4 extractions Variable LIIMx at T1 AL at T1 ICW at T1 IPW at T1 IMW at T1 LIIMx at T2 AL at T2 ICW at T2 IPW at T2 IMW at T2 LIIMx at T3 AL at T3 ICW at T3 IPW at T3 IMW at T3 LIIMx, T2-T1 AL, T2-T1 ICW, T2-T1 IPW, T2-T1 IMW, T2-T1 LIIMx, T3-T2 AL, T3-T2 ICW, T3-T2 IPW, T3-T2 IMW, T3-T2
Mean 8.59A 71.04A 34.78A 37.87A 49.31A 0.80A 62.05A 34.73A 36.31A 47.79AB 1.79A 60.66A 34.58A 35.28A 47.12A 7.79A 8.99A 0.05A 1.57A 1.53AB 0.97A 1.39A 0.16A 1.03A 0.66A
SD 3.08 3.79 2.25 2.18 2.80 0.90 2.20 1.75 1.77 2.32 1.59 2.26 1.58 2.05 2.77 2.88 3.10 2.06 1.85 2.14 1.28 1.37 1.02 0.97 1.28
Group 2, Class II Division 1, 4 extractions Mean 11.10A 70.48A 34.56A 36.72A 48.71A 0.61A 62.91A 35.59A 37.19A 48.55A 2.07A 61.40A 35.03A 36.04A 48.47A 10.48B 7.56A 1.03A 0.46B 0.16A 1.46A 1.50A 0.56A 1.15A 0.42A
SD 4.46 4.38 2.81 2.60 3.28 0.52 1.96 2.00 1.77 2.61 1.44 3.59 1.97 2.05 2.66 4.35 4.38 2.16 1.83 2.72 1.42 2.47 1.15 0.58 1.91
Group 3, Class II Division 1, 2 extractions Mean 9.68A 69.88A 34.49A 37.51A 49.24A 0.64A 61.06A 34.72A 35.91A 46.44B 1.43A 60.13A 34.87A 35.33A 46.47A 9.05AB 8.82A 0.24A 1.59A 2.80B 0.79A 0.93A 0.15A 0.58A 0.02A
SD 4.00 3.63 2.90 2.01 2.11 0.55 2.98 1.55 1.39 2.07 1.03 3.01 2.22 2.11 2.66 3.93 4.10 2.24 1.51 1.82 1.05 1.36 1.30 1.44 1.66
P 0.077 0.590 0.917 0.219 0.732 0.601 0.096 0.194 0.052 0.020* 0.361 0.381 0.689 0.406 0.151 0.043* 0.401 0.216 0.000* 0.002* 0.223 0.544 0.155 0.255 0.301
Different letters indicate statistically significant differences. *Statistically significant at P \0.05.
study.2,6,11-19 An additional inclusion criterion was the quality of treatment results as evaluated by the PAR index. This criterion is rarely a factor for sample selection,20 which has generated speculation that greater relapse might occur in patients with
compromised results after active treatment.4,21-23 Another inclusion criterion was the severity of the initial Class II molar relationship. Two groups had only patients with three-quarter cusp or full-cusp Class II molar relationships. This allowed a more precise comparison
American Journal of Orthodontics and Dentofacial Orthopedics
June 2011 Vol 139 Issue 6
Quaglio et al
772
Table V. Correlations among the variables Variable LIIMx at T1 3 LIIMx at T2 LIIMx at T1 3 LIIMx at T3 LIIMx at T1 3 LIIMx, T3-T2 LIIMx at T2 3 LIIMx at T3 LIIMx at T3 3 AL at T3 LIIMx at T3 3 ICW at T3 LIIMx at T3 3 IPW at T3 LIIMx at T3 3 IMW at T3 LIIMx at T3 3 T2 observation LIIMx at T3 3 T3 observation LIIMx at T3 3 treatment time LIIMx at T3 3 retention time LIIMx at T3 3 T1 age LIIMx at T3 3 T2 age LIIMx at T3 3 T3 age LIIMx, T3-T2 3 AL, T3-T2 LIIMx, T3-T2 3 ICW, T3-T2 LIIMx, T3-T2 3 IPW, T3-T2 LIIMx, T3-T2 3 IMW, T3-T2 LIIMx, T3-T2 3 T2 observation LIIMx, T3-T2 3 T3 observation LIIMx, T3-T2 3 treatment time A at T1 3 A at T3 B at T1 3 B at T3 C at T1 3 C at T3 D at T1 3 D at T3 E at T1 3 E at T3
R 0.2227 0.3596 0.2698 0.4380 0.0449 0.0973 0.1338 0.0061 0.1160 0.1090 0.1675 0.0149 0.0929 0.0035 0.1207 0.0557 0.1371 0.1819 0.0740 0.1947 0.1852 0.2010 0.1504 0.4586 0.3592 0.4977 0.0386
Table VI. Intersubgroup comparison of relapse perP 0.064 0.002* 0.024* 0.000* 0.712 0.423 0.270 0.960 0.339 0.369 0.166 0.902 0.444 0.977 0.319 0.647 0.258 0.132 0.542 0.106 0.125 0.095 0.214 0.000* 0.002* 0.000* 0.751
*Statistically significant at P \0.05.
of maxillary anterior tooth alignment behavior in malocclusions with extremely different interarch anteroposterior discrepancies. Patient records indicating a muscular imbalance were not included in the sample to minimize the influence of this factor on tooth alignment.17,18 Another exclusion criterion was an open-bite malocclusion. However, even with this careful selection, it cannot be stated that a muscle imbalance had no influence on the results because muscle pressure is difficult to quantify.17,24,25 A factor that was not used in the inclusion criteria was the presence of third molars because many studies have shown that these teeth do not interfere in anterior crowding relapse.26-32 The most challenging aspect of any retrospective study is to obtain a significant number of patients with complete records. The rigid inclusion criteria of this study limited its sample size. However, many current retrospective studies had similar sample sizes from which important conclusions were drawn.6,19,25,33-35 Additionally, the method error results compared favorably to those in other studies and ensured measuring reliability14,36 (Table I). Treatment time was longer in group 2 than in group 1; this was expected because the molar relationship must
June 2011 Vol 139 Issue 6
centages (t test)
Variable Relapse (%)
Group A LIIMx at T1 \7 mm 15.41
SD 12.12
Group B LIIMx at T1 .7 mm 12.40
SD 16.86
P 0.068
be corrected in Class II malocclusions treated with 4-premolar extractions37 (Table III). Nevertheless, treatment time does not seem to be related to the risk of crowding relapse, because a longer treatment does not reduce the risk of crowding relapse.14 Intergroup comparisons did not show differences in stability of maxillary anterior alignment. There was only greater correction of maxillary anterior crowding in group 2 than in group 1 during treatment. This seems to be reasonable because, despite not being significant, maxillary anterior crowding in group 2 was greater than in group 1, and both groups finished with similar alignments at T2 (Table IV). AL and ICW were similar at the 3 stages and also behaved similarly in the groups during the treatment and posttreatment periods (Table IV). With treatment, IPW tended to increase in group 2 and to decrease in groups 1 and 3, with significant differences (Table IV). This tendency to increase was probably due to some distalization of the premolars to correct the Class II anteroposterior discrepancy in group 2.38,39 IMW at T2 was significantly smaller in group 3 than in group 2, and the decrease in IMW was significantly greater in group 3 than in group 2 during treatment (Table IV). As explained for the premolars, these differences might be consequent to the need for some distalization of the molars to correct the Class II anteroposterior discrepancy in group 2. In group 3, where only 2 maxillary premolars were extracted, the maxillary molars might have experienced some mesialization.40 Because the results of intergroup comparisons showed no significant differences in maxillary anterior crowding in the LIIMx at T3 and from T3 to T2, the groups were pooled. Therefore, the LIIMx at T2 of the whole sample was 0.70 mm, which is smaller than or similar to other results of maxillary and mandibular anterior crowding.6,13,14 At T3, the LIIMx index was 1.76 mm, showing a relapse of 1.06 mm that was similar to other studies and classified as a small relapse.6,13,14,16,41 The whole sample showed stability of 88.12%. Groups 1, 2, and 3 had maxillary anterior alignment stability values of 87.55%, 86.07%, and 91.27%, respectively. The positive significant correlation between the LIIMx at T1 and T3, and the initial crowding and relapse amounts, mean that the greater the initial crowding, the
American Journal of Orthodontics and Dentofacial Orthopedics
Quaglio et al
greater the risk of relapse, corroborating some studies of mandibular anterior crowding relapse (Table V).4,20,21,42 The positive significant correlation between T2 and T3 crowding implies that there is a tendency for the remaining crowding at T2 to worsen with time. Therefore, better alignment at T2 will also provide better alignment at T3 (Table V). Because the linear distances B, C, and D had statistically significant positive correlations at T1 and T3, and because 77% of the linear displacements of the anatomic contact points had the same direction at T1 and T3, it can be concluded that the maxillary anterior teeth have a tendency to return to their original positions, as also previously observed with the mandibular teeth.4,5 It was shown that the amount of maxillary anterior crowding at T1 is correlated with its amount of relapse (Table V). Nevertheless, one cannot infer that the initial amount of crowding is associated with the percentage of relapse because subgroups A and B did not show statistically significant differences regarding relapse (Table VI). Subgroup A, with less initial crowding, had a greater relapse percentage (15.41%) than did subgroup B (12.40%). The explanation for this is that, with a small crowding correction, slight relapse amounts might represent a greater percentage of initial crowding than would a small percentage in severe crowding.14,16 These results are supported by previous studies.14,16,43 Some studies have shown that crowding relapse is associated to changes in ICW, IPW, and IMW during and after treatment,13,21,44,45 but our results did not confirm the association of crowding relapse with posttreatment transversal changes, which have also been found by others.14,36,46,47 Therefore, it seems that this is still a controversial issue that must be further investigated. Most studies have shown that crowding relapse appears to be multifactorial; this could account for the lack of significant correlations between crowding relapse and the transverse posttreatment changes investigated.3,6,13,16,20,21,42,48-54 There is no single clinical factor that influences crowding relapse but, rather, an interaction of several factors. Long-term stability is a challenge for all orthodontists because it is almost impossible to guarantee absolute posttreatment stability. This implies that orthodontists and laypeople associate treatment success with long-term stability.15 Even though this study and others on maxillary anterior crowding showed high stability percentages (88.12%), orthodontists should be cautious because 77% of the maxillary anterior teeth tend to return to their original positions.5,6,13,19,45,47 If patients seek orthodontic treatment to have an esthetic smile, they
773
certainly do not expect that their teeth will return to their original crowded positions with time. This clinical knowledge helps orthodontists set their treatments and retention plans with greater emphasis on the crowded teeth during and after treatment. CONCLUSIONS
1.
2.
3.
The stability of maxillary anterior alignment between Class I and Class II malocclusions treated with extractions was similar. The stability of maxillary anterior alignment in the whole sample was 88.12%. Class I malocclusion treated with the 4 first premolar extractions, Class II Division 1 malocclusion treated with 4 first maxillary premolar extractions, and Class II Division 1 malocclusion treated with 2 first maxillary premolar extractions had stability values of 87.55%, 86.07%, and 91.27%, respectively. Even though the results suggest that stability of the maxillary anterior alignment is high, caution is recommended because the maxillary anterior teeth tend to return to their original positions.
REFERENCES 1. Heiser W, Niederwanger A, Bancher B, Bittermann G, Neunteufel N, Kulmer S. Three-dimensional dental arch and palatal form changes after extraction and nonextraction treatment. Part 1. Arch length and area. Am J Orthod Dentofacial Orthop 2004;126:71-81. 2. Huang L, Artun J. Is the postretention relapse of maxillary and mandibular incisor alignment related? Am J Orthod Dentofacial Orthop 2001;120:9-19. 3. Sadowsky C, Sakols EI. Long-term assessment of orthodontic relapse. Am J Orthod 1982;82:456-63. 4. Surbeck BT, Artun J, Hawkins NR, Leroux B. Associations between initial, posttreatment, and postretention alignment of maxillary anterior teeth. Am J Orthod Dentofacial Orthop 1998;113: 186-95. 5. Naraghi S, Andren A, Kjellberg H, Mohlin BO. Relapse tendency after orthodontic correction of upper front teeth retained with a bonded retainer. Angle Orthod 2006;76:570-6. 6. Destang DL, Kerr WJ. Maxillary retention: is longer better? Eur J Orthod 2003;25:65-9. 7. Espeland LV, Stenvik A. Perception of personal dental appearance in young adults: relationship between occlusion, awareness, and satisfaction. Am J Orthod Dentofacial Orthop 1991;100:234-41. 8. Helm S, Kreiborg S, Solow B. Psychosocial implications of malocclusion: a 15-year follow-up study in 30-year-old Danes. Am J Orthod 1985;87:110-8. 9. Little RM. The irregularity index: a quantitative score of mandibular anterior alignment. Am J Orthod 1975;68:554-63. 10. Dahlberg G. Statistical methods for medical and biological students. New York: Interscience Publications; 1940. 11. Blake M, Bibby K. Retention and stability: a review of the literature. Am J Orthod Dentofacial Orthop 1998;114:299-306. 12. Bondemark L, Holm AK, Hansen K, Axelsson S, Mohlin B, Brattstrom V, et al. Long-term stability of orthodontic treatment
American Journal of Orthodontics and Dentofacial Orthopedics
June 2011 Vol 139 Issue 6
Quaglio et al
774
13. 14.
15.
16.
17.
18. 19.
20.
21.
22. 23. 24. 25.
26.
27.
28. 29. 30.
31. 32. 33.
34. 35.
and patient satisfaction. A systematic review. Angle Orthod 2007; 77:181-91. Vaden JL, Harris EF, Gardner RL. Relapse revisited. Am J Orthod Dentofacial Orthop 1997;111:543-53. Freitas KM, Freitas MR, Henriques JF, Pinzan A, Janson G. Postretention relapse of mandibular anterior crowding in patients treated without mandibular premolar extraction. Am J Orthod Dentofacial Orthop 2004;125:480-7. Little RM, Riedel RA, Engst ED. Serial extraction of first premolars— postretention evaluation of stability and relapse. Angle Orthod 1990;60:255-62. Little RM, Wallen TR, Riedel RA. Stability and relapse of mandibular anterior alignment—first premolar extraction cases treated by traditional edgewise orthodontics. Am J Orthod 1981;80:349-65. Pepicelli A, Woods M, Briggs C. The mandibular muscles and their importance in orthodontics: a contemporary review. Am J Orthod Dentofacial Orthop 2005;128:774-80. Proffit WR. Equilibrium theory revisited: factors influencing position of the teeth. Angle Orthod 1978;48:175-86. Taner TU, Haydar B, Kavuklu I, Korkmaz A. Short-term effects of fiberotomy on relapse of anterior crowding. Am J Orthod Dentofacial Orthop 2000;118:617-23. Artun J, Garol JD, Little RM. Long-term stability of mandibular incisors following successful treatment of Class II, Division 1, malocclusions. Angle Orthod 1996;66:229-38. Kahl-Nieke B, Fischbach H, Schwarze CW. Post-retention crowding and incisor irregularity: a long-term follow-up evaluation of stability and relapse. Br J Orthod 1995;22:249-57. Roth RH. Functional occlusion for the orthodontist. Part III. J Clin Orthod 1981;15:174-9, 82-98. Zachrisson BU. Important aspects of long-term stability. J Clin Orthod 1997;31:562-83. Carter GA, McNamara JA Jr. Longitudinal dental arch changes in adults. Am J Orthod Dentofacial Orthop 1998;114:88-99. Eslambolchi S, Woodside DG, Rossouw PE. A descriptive study of mandibular incisor alignment in untreated subjects. Am J Orthod Dentofacial Orthop 2008;133:343-53. Ades AG, Joondeph DR, Little RM, Chapko MK. A long-term study of the relationship of third molars to changes in the mandibular dental arch. Am J Orthod Dentofacial Orthop 1990;97:323-35. Little RM, Riedel RA, Stein A. Mandibular arch length increase during the mixed dentition: postretention evaluation of stability and relapse. Am J Orthod Dentofacial Orthop 1990;97:393-404. Little RM. Stability and relapse of dental arch alignment. Br J Orthod 1990;17:235-41. Southard TE, Southard KA, Weeda LW. Mesial force from unerupted third molars. Am J Orthod Dentofacial Orthop 1991;99:220-5. Harradine NW, Pearson MH, Toth B. The effect of extraction of third molars on late lower incisor crowding: a randomized controlled trial. Br J Orthod 1998;25:117-22. Bishara SE. Third molars: a dilemma! Or is it? Am J Orthod Dentofacial Orthop 1999;115:628-33. Sidlauskas A, Trakiniene G. Effect of the lower third molars on the lower dental arch crowding. Stomatologija 2006;8:80-4. Acar A, Alcan T, Erverdi N. Evaluation of the relationship between the anterior component of occlusal force and postretention crowding. Am J Orthod Dentofacial Orthop 2002;122:366-70. Melsen B, Dalstra M. Distal molar movement with Kloehn headgear: is it stable? Am J Orthod Dentofacial Orthop 2003;123:374-8. Janson G, Busato MC, Henriques JF, Freitas MR, Freitas LM. Alignment stability in Class II malocclusion treated with 2- and 4-premolar extraction protocols. Am J Orthod Dentofacial Orthop 2006;130:189-95.
June 2011 Vol 139 Issue 6
36. Paquette DE, Beattie JR, Johnston LE Jr. A long-term comparison of nonextraction and premolar extraction edgewise therapy in "borderline" Class II patients. Am J Orthod Dentofacial Orthop 1992;102:1-14. 37. Janson G, Maria FR, Barros SE, Freitas MR, Henriques JF. Orthodontic treatment time in 2- and 4-premolar-extraction protocols. Am J Orthod Dentofacial Orthop 2006;129:666-71. 38. Bishara SE, Bayati P, Zaher AR, Jakobsen JR. Comparisons of the dental arch changes in patients with Class II, division 1 malocclusions: extraction vs nonextraction treatments. Angle Orthod 1994; 64:351-8. 39. Bishara SE, Cummins DM, Zaher AR. Treatment and posttreatment changes in patients with Class II, Division 1 malocclusion after extraction and nonextraction treatment. Am J Orthod Dentofacial Orthop 1997;111:18-27. 40. Kahl-Nieke B, Fischbach H, Schwarze CW. Treatment and postretention changes in dental arch width dimensions—a long-term evaluation of influencing cofactors. Am J Orthod Dentofacial Orthop 1996;109:368-78. 41. Little RM, Riedel RA, Artun J. An evaluation of changes in mandibular anterior alignment from 10 to 20 years postretention. Am J Orthod Dentofacial Orthop 1988;93:423-8. 42. Ormiston JP, Huang GJ, Little RM, Decker JD, Seuk GD. Retrospective analysis of long-term stable and unstable orthodontic treatment outcomes. Am J Orthod Dentofacial Orthop 2005;128:568-74. 43. Miyazaki H, Motegi E, Yatabe K, Isshiki Y. Occlusal stability after extraction orthodontic therapy in adult and adolescent patients. Am J Orthod Dentofacial Orthop 1998;114:530-7. 44. Gianelly A. Evidence-based therapy: an orthodontic dilemma. Am J Orthod Dentofacial Orthop 2006;129:596-8. 45. Heiser W, Richter M, Niederwanger A, Neunteufel N, Kulmer S. Association of the canine guidance angle with maxillary and mandibular intercanine widths and anterior alignment relapse: extraction vs nonextraction treatment. Am J Orthod Dentofacial Orthop 2008;133:669-80. 46. BeGole EA, Fox DL, Sadowsky C. Analysis of change in arch form with premolar expansion. Am J Orthod Dentofacial Orthop 1998; 113:307-15. 47. Erdinc AE, Nanda RS, Isiksal E. Relapse of anterior crowding in patients treated with extraction and nonextraction of premolars. Am J Orthod Dentofacial Orthop 2006;129:775-84. 48. Uhde MD, Sadowsky C, BeGole EA. Long-term stability of dental relationships after orthodontic treatment. Angle Orthod 1983; 53:240-52. 49. Bishara SE, Jakobsen JR, Treder JE, Stasi MJ. Changes in the maxillary and mandibular tooth size-arch length relationship from early adolescence to early adulthood. A longitudinal study. Am J Orthod Dentofacial Orthop 1989;95:46-59. 50. Little RM, Riedel RA. Postretention evaluation of stability and relapse—mandibular arches with generalized spacing. Am J Orthod Dentofacial Orthop 1989;95:37-41. 51. Artun J, Krogstad O, Little RM. Stability of mandibular incisors following excessive proclination: a study in adults with surgically treated mandibular prognathism. Angle Orthod 1990;60:99-106. 52. Luppanapornlarp S, Johnston LE Jr. The effects of premolar extraction: a long-term comparison of outcomes in "clear-cut" extraction and nonextraction Class II patients. Angle Orthod 1993;63:257-72. 53. Sadowsky C, Schneider BJ, BeGole EA, Tahir E. Long-term stability after orthodontic treatment: nonextraction with prolonged retention. Am J Orthod Dentofacial Orthop 1994;106:243-9. 54. Harris EH, Gardner RZ, Vaden JL. A longitudinal cephalometric study of postorthodontic craniofacial changes. Am J Orthod Dentofacial Orthop 1999;115:77-82.
American Journal of Orthodontics and Dentofacial Orthopedics
Stability and relapse of maxillary anterior crowding treatment in Class I and Class II Division 1 malocclusions Camila Leite Quaglio,a Karina Maria Salvatore de Freitas,b Marcos Roberto de Freitas,c Guilherme Janson,c Fernando Castanha Henriquesc and Jose Bauru, S~ao Paulo, Brazil Introduction: The maxillary anterior teeth are the most important to facial esthetics because they are the first to show on a smile. Therefore, stability of the maxillary anterior teeth alignment is an important issue. The objective of this study was to compare the stability of maxillary anterior tooth alignment in Class I and Class II Division 1 malocclusions. Methods: The sample comprised dental casts of 70 patients with Class I and Class II Division 1 malocclusions and a minimum of 3 mm of maxillary anterior crowding measured by an irregularity index. The patients were treated with extractions and evaluated at pretreatment and posttreatment and at least 5 years after treatment. The sample was divided into 3 groups: group 1, Class I malocclusion treated with 4 first premolar extractions comprising 30 subjects, with an initial age of 13.16 years and 8.59 mm of initial maxillary irregularity; group 2, Class II malocclusion treated with 4 first premolar extractions comprising 20 subjects, with an initial age of 12.95 years and 11.10 mm of maxillary irregularity; and group 3, Class II malocclusion treated with 2 first maxillary premolar extractions comprising 20 subjects, with an initial age of 13.09 years and 9.68 mm of maxillary irregularity. Results: The decrease in the maxillary irregularity index was significantly greater in group 2 than in group 1 during treatment. The stability of maxillary anterior alignment was 88.12% over the long term; 77% of the linear displacement of the anatomic contact points tended to return to their original positions. Conclusions: Stability of maxillary anterior alignment between the 3 groups was similar. The stability of maxillary anterior alignment was high over the long term, but a high percentage of teeth tended to return to their original positions. (Am J Orthod Dentofacial Orthop 2011;139:768-74)
E
sthetic treatments are common nowadays because concern with facial appearance has greatly increased in the last decades. Alignment of the maxillary anterior teeth is especially important for an esthetic smile, since they are the first to show. Many patients seek orthodontic treatment to align these teeth. Correct orthodontic treatment improves facial esthetics as well as the occlusion, but long-term stability of the aligned teeth is highly variable and unpredictable. Greater research emphasis has been placed on relapse of mandibular anterior crowding probably because a Orthodontic graduate student, Department of Orthodontics, Bauru Dental School, University of S~ao Paulo, Bauru, S~ao Paulo, Brazil. b and UNORP. Professor of UNINGA c Professor and head, Department of Orthodontics, Bauru Dental School, University of S~ao Paulo, Bauru, S~ao Paulo, Brazil. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Camila Leite Quaglio, Rua Visconde de Castro, 573, S~ao Paulo, SP, 04611-050, Brazil; e-mail, [email protected]. Submitted, April 2009; revised and accepted, October 2009. 0889-5406/$36.00 Copyright Ó 2011 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2009.10.044
768
alignment stability of these teeth is less than that of the maxillary anterior teeth.1-4 Nevertheless, little emphasis has been given to investigating the direction of relapse.4,5 Patients tend to judge orthodontic treatment success primarily by maxillary anterior tooth alignment.5-8 Therefore, long-term stability investigations of maxillary anterior tooth alignment have become important in orthodontics. Because of insufficient studies on maxillary anterior tooth alignment, the objectives of this investigation were to evaluate the amount and direction of relapse of maxillary anterior crowding in different extraction protocols, compare the relapse amounts in Class I and Class II Division 1 malocclusions, and evaluate possible relationships between crowding relapse and intercanine, interpremolar, and intermolar widths, arch lengths, and amounts of initial maxillary anterior crowding. MATERIAL AND METHODS
The sample was retrospectively selected from over 4500 patient records treated by graduate students in the Department of Orthodontics at Bauru Dental School,
Quaglio et al
University of S~ao Paulo, Brazil. The selection criteria were patients under 15 years of age at pretreatment (T1), with all permanent teeth erupted up to the first molars; no supernumerary teeth or tooth agenesis; Class I or Class II Division 1 malocclusion of at least three-quarter cusp Class II molar relationship; and more than 3 mm of crowding on Little’s irregularity index9 in the mandible (LIIMx). The patients also had a maximum peer assessment rating (PAR) score of 5 at posttreatment (T2), and balanced faces and passive lip seal. Subjects with anterior open bite or crossbite malocclusion were not included. Therefore, the sample comprised 70 patients divided into 3 groups, evaluated at 3 stages: T1, T2, and postretention (T3). Thirty had Class I and 40 had Class II Division 1 malocclusions (5 had three-quarter cusp, and 65 had full-cusp Class II molar relationships). Group 1 comprised 30 patients (12 boys, 18 girls) with Class I malocclusion treated with 4 first premolar extractions. Mean initial maxillary anterior crowding, initial age, and treatment time were 8.59 mm (SD, 3.08), 13.16 years (SD, 0.97), and 1.99 years (SD, 0.51), respectively. Group 2 consisted of 20 patients (11 boys, 9 girls) with Class II Division 1 malocclusion treated with 4 first premolar extractions. Mean initial maxillary anterior crowding, initial age, and treatment time were 11.10 mm (SD, 4.46), 12.95 years (SD, 1.08), and 2.48 years (SD, 0.72), respectively. Group 3 comprised 20 patients (9 boys, 11 girls) with Class II Division 1 malocclusions treated with 2 maxillary first premolar extractions. Mean initial maxillary anterior crowding, initial age, and treatment time were 9.68 mm (SD, 4.00), 13.09 years (SD, 1.11), and 2.05 years (SD, 0.45), respectively. All patients were treated with fixed edgewise appliances. Anterior retraction was performed by sliding mechanics with elastic chains. All patients used an extraoral appliance for anchorage reinforcement, as needed, during active treatment. No patient underwent interproximal stripping, rapid maxillary expansion, or fiberotomy as part of the treatment plan. Class II elastics were used when necessary, especially in the Class II malocclusion patients treated with 4 maxillary premolar extractions. Retention included a maxillary Hawley plate and a bonded lingual canine-to-canine retainer in the mandibular arch. The assessed variables consisted of LIIMx, arch length (AL), intercanine width (ICW), interpremolar width (IPW), and intermolar width (IMW) (Figs 1 and 2). All dental cast measurements were made with a 0.01-mm precision digital caliper (Mitutoyo America, Aurora, Ill) by the same examiner (C.L.Q.). To investigate the direction of relapse, each linear displacement of the anatomic contact points was
769
Fig 1. Little’s irregularity index in the maxillary arch.
Fig 2. A 1 B 5 arch length; C 5 intercanine width; D 5 interpremolar width; E 5 intermolar width.
separately evaluated at T1 and T3 in the maxillary arch.9 The contact points (A, B, C, D, and E) were evaluated by taking into account the direction of each anterior tooth in relation to its adjacent tooth (labial or lingual). The relapse percentage was calculated as the ratio between the relapse and the correction amounts. To analyze whether the percentage of relapse was associated with the amount of initial crowding, the whole sample was divided into 2 subgroups according to initial crowding. Subgroup A comprised patients with LIIMx scores less than 7 mm, or minimal and moderate irregularity (19 patients), and subgroup B had LIIMx scores equal to or greater than 7 mm, or severe and very severe irregularity (51 patients).9 A month after the first measurements, randomly selected dental casts of 15 patients (21% of the whole
American Journal of Orthodontics and Dentofacial Orthopedics
June 2011 Vol 139 Issue 6
Quaglio et al
770
sample) were remeasured by the same examiner (C.L.Q.) in all stages (T1, T2, and T3). Casual errors were P calculated according to Dahlberg’s formula (SE2 5 d2 =2n),10 where SE2 is the error variance and d is the difference between 2 determinations of the same variable. Systematic errors were evaluated with dependent t tests at P \0.05. Statistical analysis
Normal distribution was verified by the KolmogorovSmirnov test. The results were nonsignificant for all variables. Intergroup sex distribution was evaluated with the chi-square test; intergroup comparisons of age, treatment, retention, posttreatment, and postretention observation times, and initial and final LIIMx scores were made with 1-way analysis of variance (ANOVA), followed by Tukey tests when necessary. These last tests were also used to evaluate intergroup comparisons of LIIMx scores, AL, and ICW, IPW, and IMW at T1, T2, and T3, and their treatment (T2-T1) and posttreatment (T3-T2) changes. Pearson correlation coefficients were used to assess the relationships of LIIMx scores at different stages with the other variables, and the relationships between linear displacements of the anatomic contact points at T1 and T3. The percentages of teeth that kept the same labiolingual direction at T1 and T3 were calculated. The relapse percentages in subgroups A and B were compared with t tests. All statistical analyses were performed with Statistica software (version 6.0, Statsoft, Tulsa, Okla), and the results were considered significant at P \0.05.
Table I. Casual and systematic errors between the first and second measurements (mm) Measurement 1 Measurement 2 Variable A at T1 B at T1 C at T1 D at T1 E at T1 LIIMx at T1 AL at T1 ICW at T1 IPW at T1 IMW at T1 A at T2 B at T2 C at T2 D at T2 E at T2 LIIMx at T2 AL at T2 ICW at T2 IPW at T2 IMW at T2 A at T3 B at T3 C at T3 D at T3 E at T3 LIIMx at T3 AL at T3 ICW at T3 IPW at T3 IMW at T3
Mean 2.67 2.10 1.10 1.08 2.58 9.52 72.24 35.04 37.28 48.84 0.05 0.18 0.09 0.16 0.20 0.69 62.68 34.69 36.64 48.50 0.25 0.32 0.31 0.38 0.42 1.69 61.48 34.65 35.62 47.62
SD 1.55 1.29 1.19 0.93 1.89 4.29 4.35 1.72 1.92 2.61 0.10 0.29 0.15 0.25 0.25 0.48 2.46 1.81 2.08 2.92 0.40 0.36 0.36 0.45 0.65 1.47 2.22 1.70 2.33 3.28
Mean 2.66 2.08 1.08 1.05 2.53 9.40 72.26 34.91 37.39 48.87 0.05 0.19 0.06 0.10 0.18 0.58 62.75 34.77 36.61 48.56 0.22 0.32 0.26 0.31 0.36 1.47 61.38 34.65 35.72 47.63
SD 1.52 1.25 1.11 0.92 1.87 4.16 4.24 1.88 1.97 2.56 0.07 0.22 0.10 0.18 0.24 0.30 2.36 1.72 2.03 2.80 0.34 0.35 0.27 0.37 0.63 1.23 2.40 1.75 2.21 3.23
Dahlberg 0.127 0.118 0.106 0.059 0.083 0.286 0.616 0.436 0.232 0.197 0.034 0.116 0.047 0.078 0.065 0.182 0.574 0.192 0.160 0.169 0.085 0.081 0.086 0.113 0.152 0.069 0.960 0.151 0.472 0.991
P 0.848 0.779 0.635 0.181 0.147 0.285 0.955 0.431 0.222 0.705 0.608 0.964 0.098 0.034* 0.424 0.091 0.737 0.265 0.671 0.333 0.275 0.813 0.104 0.081 0.152 0.069 0.961 0.151 0.472 0.991
*Statistically significant at P \0.05.
RESULTS
No variable showed a casual error greater than 1 mm. Among 30 variables, only width D at T2 showed a statistically significant systematic error (Table I). The groups were compatible regarding all variables, except that group 2 had a significantly longer treatment time than group 1 (Tables II and III). Decreases in the LIIMx scores were significantly greater in group 2 than in group 1 during treatment. The increase in IPW was significantly greater in group 2 than in groups 1 and 3, in which it decreased during treatment. IMW at T2 was significantly smaller in group 3 than in group 2. The decrease in IMW was significantly greater in group 3 than in group 2 during treatment (Table IV). There were positive significant correlations between the T1 and the T3 LIIMx scores, between the T1 LIIMx score and the relapse at T3, and between the T2 and T3 LIIMx scores (Table V). There were significant positive correlations between linear displacements of anatomic contact points B, C,
June 2011 Vol 139 Issue 6
Table II. Intergroup comparison of sex distribution
(chi-square test)
Sex Male Female Total
Group 1, Class I, 4 extractions 12 18 30
Group 2, Class II Division 1, 4 extractions 11 9 20
Group 3, Class II Division 1, 2 extractions 11 9 20
Total 34 36 70
Chi-square 51.544; df 5 2; P 5 0.462.
and D at T1 and T3 (Table V), and 77% of the linear displacements of the anatomic contact points had the same direction at T1 and T3. There was no significant difference between subgroups A and B regarding the relapse percentages (Table VI). DISCUSSION
The sample was selected by previously described valid inclusion criteria and according to the objectives of the
American Journal of Orthodontics and Dentofacial Orthopedics
Quaglio et al
771
Table III. Intergroup comparisons of age, treatment, retention, posttreatment and postretention observation times,
initial and final LIIMx scores (ANOVA followed by Tukey tests) Group 1, Class I, 4 extractions Variable T1 age (y) T2 age (y) T3 age (y) Treatment time (y) Retention time (y) T2 observation (y) T3 observation (y) LIIMx at T1 (mm) LIIMx at T2 (mm)
Mean 13.16A 15.15A 23.71A 1.99A 1.24A 8.55A 7.31A 8.59A 0.80A
SD 0.97 1.14 2.80 0.51 0.53 3.03 3.18 3.08 0.90
Group 2, Class II Division 1, 4 extractions Mean 12.95A 15.43A 24.97A 2.48B 1.28A 9.54A 8.26A 11.10A 0.61A
SD 1.08 1.28 4.02 0.72 0.54 4.27 4.47 4.46 0.52
Group 3, Class II Division 1, 2 extractions Mean 13.09A 15.14A 25.02A 2.05AB 1.10A 9.88A 8.78A 9.68A 0.64A
SD 1.11 1.10 2.85 0.45 0.27 2.87 2.95 4.00 0.55
P 0.760 0.604 0.159 0.01* 0.419 0.209 0.191 0.077 0.601
Different letters indicate statistically significant differences. *Statistically significant at P \0.05.
Table IV. Intergroup comparisons (mm) of LIIMx scores, AL, ICW, IPW, and IMW at T1, T2, and T3, and their treatment (T2-T1) and posttreatment (T3-T2) changes (1-way ANOVA followed by Tukey tests) Group 1, Class I, 4 extractions Variable LIIMx at T1 AL at T1 ICW at T1 IPW at T1 IMW at T1 LIIMx at T2 AL at T2 ICW at T2 IPW at T2 IMW at T2 LIIMx at T3 AL at T3 ICW at T3 IPW at T3 IMW at T3 LIIMx, T2-T1 AL, T2-T1 ICW, T2-T1 IPW, T2-T1 IMW, T2-T1 LIIMx, T3-T2 AL, T3-T2 ICW, T3-T2 IPW, T3-T2 IMW, T3-T2
Mean 8.59A 71.04A 34.78A 37.87A 49.31A 0.80A 62.05A 34.73A 36.31A 47.79AB 1.79A 60.66A 34.58A 35.28A 47.12A 7.79A 8.99A 0.05A 1.57A 1.53AB 0.97A 1.39A 0.16A 1.03A 0.66A
SD 3.08 3.79 2.25 2.18 2.80 0.90 2.20 1.75 1.77 2.32 1.59 2.26 1.58 2.05 2.77 2.88 3.10 2.06 1.85 2.14 1.28 1.37 1.02 0.97 1.28
Group 2, Class II Division 1, 4 extractions Mean 11.10A 70.48A 34.56A 36.72A 48.71A 0.61A 62.91A 35.59A 37.19A 48.55A 2.07A 61.40A 35.03A 36.04A 48.47A 10.48B 7.56A 1.03A 0.46B 0.16A 1.46A 1.50A 0.56A 1.15A 0.42A
SD 4.46 4.38 2.81 2.60 3.28 0.52 1.96 2.00 1.77 2.61 1.44 3.59 1.97 2.05 2.66 4.35 4.38 2.16 1.83 2.72 1.42 2.47 1.15 0.58 1.91
Group 3, Class II Division 1, 2 extractions Mean 9.68A 69.88A 34.49A 37.51A 49.24A 0.64A 61.06A 34.72A 35.91A 46.44B 1.43A 60.13A 34.87A 35.33A 46.47A 9.05AB 8.82A 0.24A 1.59A 2.80B 0.79A 0.93A 0.15A 0.58A 0.02A
SD 4.00 3.63 2.90 2.01 2.11 0.55 2.98 1.55 1.39 2.07 1.03 3.01 2.22 2.11 2.66 3.93 4.10 2.24 1.51 1.82 1.05 1.36 1.30 1.44 1.66
P 0.077 0.590 0.917 0.219 0.732 0.601 0.096 0.194 0.052 0.020* 0.361 0.381 0.689 0.406 0.151 0.043* 0.401 0.216 0.000* 0.002* 0.223 0.544 0.155 0.255 0.301
Different letters indicate statistically significant differences. *Statistically significant at P \0.05.
study.2,6,11-19 An additional inclusion criterion was the quality of treatment results as evaluated by the PAR index. This criterion is rarely a factor for sample selection,20 which has generated speculation that greater relapse might occur in patients with
compromised results after active treatment.4,21-23 Another inclusion criterion was the severity of the initial Class II molar relationship. Two groups had only patients with three-quarter cusp or full-cusp Class II molar relationships. This allowed a more precise comparison
American Journal of Orthodontics and Dentofacial Orthopedics
June 2011 Vol 139 Issue 6
Quaglio et al
772
Table V. Correlations among the variables Variable LIIMx at T1 3 LIIMx at T2 LIIMx at T1 3 LIIMx at T3 LIIMx at T1 3 LIIMx, T3-T2 LIIMx at T2 3 LIIMx at T3 LIIMx at T3 3 AL at T3 LIIMx at T3 3 ICW at T3 LIIMx at T3 3 IPW at T3 LIIMx at T3 3 IMW at T3 LIIMx at T3 3 T2 observation LIIMx at T3 3 T3 observation LIIMx at T3 3 treatment time LIIMx at T3 3 retention time LIIMx at T3 3 T1 age LIIMx at T3 3 T2 age LIIMx at T3 3 T3 age LIIMx, T3-T2 3 AL, T3-T2 LIIMx, T3-T2 3 ICW, T3-T2 LIIMx, T3-T2 3 IPW, T3-T2 LIIMx, T3-T2 3 IMW, T3-T2 LIIMx, T3-T2 3 T2 observation LIIMx, T3-T2 3 T3 observation LIIMx, T3-T2 3 treatment time A at T1 3 A at T3 B at T1 3 B at T3 C at T1 3 C at T3 D at T1 3 D at T3 E at T1 3 E at T3
R 0.2227 0.3596 0.2698 0.4380 0.0449 0.0973 0.1338 0.0061 0.1160 0.1090 0.1675 0.0149 0.0929 0.0035 0.1207 0.0557 0.1371 0.1819 0.0740 0.1947 0.1852 0.2010 0.1504 0.4586 0.3592 0.4977 0.0386
Table VI. Intersubgroup comparison of relapse perP 0.064 0.002* 0.024* 0.000* 0.712 0.423 0.270 0.960 0.339 0.369 0.166 0.902 0.444 0.977 0.319 0.647 0.258 0.132 0.542 0.106 0.125 0.095 0.214 0.000* 0.002* 0.000* 0.751
*Statistically significant at P \0.05.
of maxillary anterior tooth alignment behavior in malocclusions with extremely different interarch anteroposterior discrepancies. Patient records indicating a muscular imbalance were not included in the sample to minimize the influence of this factor on tooth alignment.17,18 Another exclusion criterion was an open-bite malocclusion. However, even with this careful selection, it cannot be stated that a muscle imbalance had no influence on the results because muscle pressure is difficult to quantify.17,24,25 A factor that was not used in the inclusion criteria was the presence of third molars because many studies have shown that these teeth do not interfere in anterior crowding relapse.26-32 The most challenging aspect of any retrospective study is to obtain a significant number of patients with complete records. The rigid inclusion criteria of this study limited its sample size. However, many current retrospective studies had similar sample sizes from which important conclusions were drawn.6,19,25,33-35 Additionally, the method error results compared favorably to those in other studies and ensured measuring reliability14,36 (Table I). Treatment time was longer in group 2 than in group 1; this was expected because the molar relationship must
June 2011 Vol 139 Issue 6
centages (t test)
Variable Relapse (%)
Group A LIIMx at T1 \7 mm 15.41
SD 12.12
Group B LIIMx at T1 .7 mm 12.40
SD 16.86
P 0.068
be corrected in Class II malocclusions treated with 4-premolar extractions37 (Table III). Nevertheless, treatment time does not seem to be related to the risk of crowding relapse, because a longer treatment does not reduce the risk of crowding relapse.14 Intergroup comparisons did not show differences in stability of maxillary anterior alignment. There was only greater correction of maxillary anterior crowding in group 2 than in group 1 during treatment. This seems to be reasonable because, despite not being significant, maxillary anterior crowding in group 2 was greater than in group 1, and both groups finished with similar alignments at T2 (Table IV). AL and ICW were similar at the 3 stages and also behaved similarly in the groups during the treatment and posttreatment periods (Table IV). With treatment, IPW tended to increase in group 2 and to decrease in groups 1 and 3, with significant differences (Table IV). This tendency to increase was probably due to some distalization of the premolars to correct the Class II anteroposterior discrepancy in group 2.38,39 IMW at T2 was significantly smaller in group 3 than in group 2, and the decrease in IMW was significantly greater in group 3 than in group 2 during treatment (Table IV). As explained for the premolars, these differences might be consequent to the need for some distalization of the molars to correct the Class II anteroposterior discrepancy in group 2. In group 3, where only 2 maxillary premolars were extracted, the maxillary molars might have experienced some mesialization.40 Because the results of intergroup comparisons showed no significant differences in maxillary anterior crowding in the LIIMx at T3 and from T3 to T2, the groups were pooled. Therefore, the LIIMx at T2 of the whole sample was 0.70 mm, which is smaller than or similar to other results of maxillary and mandibular anterior crowding.6,13,14 At T3, the LIIMx index was 1.76 mm, showing a relapse of 1.06 mm that was similar to other studies and classified as a small relapse.6,13,14,16,41 The whole sample showed stability of 88.12%. Groups 1, 2, and 3 had maxillary anterior alignment stability values of 87.55%, 86.07%, and 91.27%, respectively. The positive significant correlation between the LIIMx at T1 and T3, and the initial crowding and relapse amounts, mean that the greater the initial crowding, the
American Journal of Orthodontics and Dentofacial Orthopedics
Quaglio et al
greater the risk of relapse, corroborating some studies of mandibular anterior crowding relapse (Table V).4,20,21,42 The positive significant correlation between T2 and T3 crowding implies that there is a tendency for the remaining crowding at T2 to worsen with time. Therefore, better alignment at T2 will also provide better alignment at T3 (Table V). Because the linear distances B, C, and D had statistically significant positive correlations at T1 and T3, and because 77% of the linear displacements of the anatomic contact points had the same direction at T1 and T3, it can be concluded that the maxillary anterior teeth have a tendency to return to their original positions, as also previously observed with the mandibular teeth.4,5 It was shown that the amount of maxillary anterior crowding at T1 is correlated with its amount of relapse (Table V). Nevertheless, one cannot infer that the initial amount of crowding is associated with the percentage of relapse because subgroups A and B did not show statistically significant differences regarding relapse (Table VI). Subgroup A, with less initial crowding, had a greater relapse percentage (15.41%) than did subgroup B (12.40%). The explanation for this is that, with a small crowding correction, slight relapse amounts might represent a greater percentage of initial crowding than would a small percentage in severe crowding.14,16 These results are supported by previous studies.14,16,43 Some studies have shown that crowding relapse is associated to changes in ICW, IPW, and IMW during and after treatment,13,21,44,45 but our results did not confirm the association of crowding relapse with posttreatment transversal changes, which have also been found by others.14,36,46,47 Therefore, it seems that this is still a controversial issue that must be further investigated. Most studies have shown that crowding relapse appears to be multifactorial; this could account for the lack of significant correlations between crowding relapse and the transverse posttreatment changes investigated.3,6,13,16,20,21,42,48-54 There is no single clinical factor that influences crowding relapse but, rather, an interaction of several factors. Long-term stability is a challenge for all orthodontists because it is almost impossible to guarantee absolute posttreatment stability. This implies that orthodontists and laypeople associate treatment success with long-term stability.15 Even though this study and others on maxillary anterior crowding showed high stability percentages (88.12%), orthodontists should be cautious because 77% of the maxillary anterior teeth tend to return to their original positions.5,6,13,19,45,47 If patients seek orthodontic treatment to have an esthetic smile, they
773
certainly do not expect that their teeth will return to their original crowded positions with time. This clinical knowledge helps orthodontists set their treatments and retention plans with greater emphasis on the crowded teeth during and after treatment. CONCLUSIONS
1.
2.
3.
The stability of maxillary anterior alignment between Class I and Class II malocclusions treated with extractions was similar. The stability of maxillary anterior alignment in the whole sample was 88.12%. Class I malocclusion treated with the 4 first premolar extractions, Class II Division 1 malocclusion treated with 4 first maxillary premolar extractions, and Class II Division 1 malocclusion treated with 2 first maxillary premolar extractions had stability values of 87.55%, 86.07%, and 91.27%, respectively. Even though the results suggest that stability of the maxillary anterior alignment is high, caution is recommended because the maxillary anterior teeth tend to return to their original positions.
REFERENCES 1. Heiser W, Niederwanger A, Bancher B, Bittermann G, Neunteufel N, Kulmer S. Three-dimensional dental arch and palatal form changes after extraction and nonextraction treatment. Part 1. Arch length and area. Am J Orthod Dentofacial Orthop 2004;126:71-81. 2. Huang L, Artun J. Is the postretention relapse of maxillary and mandibular incisor alignment related? Am J Orthod Dentofacial Orthop 2001;120:9-19. 3. Sadowsky C, Sakols EI. Long-term assessment of orthodontic relapse. Am J Orthod 1982;82:456-63. 4. Surbeck BT, Artun J, Hawkins NR, Leroux B. Associations between initial, posttreatment, and postretention alignment of maxillary anterior teeth. Am J Orthod Dentofacial Orthop 1998;113: 186-95. 5. Naraghi S, Andren A, Kjellberg H, Mohlin BO. Relapse tendency after orthodontic correction of upper front teeth retained with a bonded retainer. Angle Orthod 2006;76:570-6. 6. Destang DL, Kerr WJ. Maxillary retention: is longer better? Eur J Orthod 2003;25:65-9. 7. Espeland LV, Stenvik A. Perception of personal dental appearance in young adults: relationship between occlusion, awareness, and satisfaction. Am J Orthod Dentofacial Orthop 1991;100:234-41. 8. Helm S, Kreiborg S, Solow B. Psychosocial implications of malocclusion: a 15-year follow-up study in 30-year-old Danes. Am J Orthod 1985;87:110-8. 9. Little RM. The irregularity index: a quantitative score of mandibular anterior alignment. Am J Orthod 1975;68:554-63. 10. Dahlberg G. Statistical methods for medical and biological students. New York: Interscience Publications; 1940. 11. Blake M, Bibby K. Retention and stability: a review of the literature. Am J Orthod Dentofacial Orthop 1998;114:299-306. 12. Bondemark L, Holm AK, Hansen K, Axelsson S, Mohlin B, Brattstrom V, et al. Long-term stability of orthodontic treatment
American Journal of Orthodontics and Dentofacial Orthopedics
June 2011 Vol 139 Issue 6
Quaglio et al
774
13. 14.
15.
16.
17.
18. 19.
20.
21.
22. 23. 24. 25.
26.
27.
28. 29. 30.
31. 32. 33.
34. 35.
and patient satisfaction. A systematic review. Angle Orthod 2007; 77:181-91. Vaden JL, Harris EF, Gardner RL. Relapse revisited. Am J Orthod Dentofacial Orthop 1997;111:543-53. Freitas KM, Freitas MR, Henriques JF, Pinzan A, Janson G. Postretention relapse of mandibular anterior crowding in patients treated without mandibular premolar extraction. Am J Orthod Dentofacial Orthop 2004;125:480-7. Little RM, Riedel RA, Engst ED. Serial extraction of first premolars— postretention evaluation of stability and relapse. Angle Orthod 1990;60:255-62. Little RM, Wallen TR, Riedel RA. Stability and relapse of mandibular anterior alignment—first premolar extraction cases treated by traditional edgewise orthodontics. Am J Orthod 1981;80:349-65. Pepicelli A, Woods M, Briggs C. The mandibular muscles and their importance in orthodontics: a contemporary review. Am J Orthod Dentofacial Orthop 2005;128:774-80. Proffit WR. Equilibrium theory revisited: factors influencing position of the teeth. Angle Orthod 1978;48:175-86. Taner TU, Haydar B, Kavuklu I, Korkmaz A. Short-term effects of fiberotomy on relapse of anterior crowding. Am J Orthod Dentofacial Orthop 2000;118:617-23. Artun J, Garol JD, Little RM. Long-term stability of mandibular incisors following successful treatment of Class II, Division 1, malocclusions. Angle Orthod 1996;66:229-38. Kahl-Nieke B, Fischbach H, Schwarze CW. Post-retention crowding and incisor irregularity: a long-term follow-up evaluation of stability and relapse. Br J Orthod 1995;22:249-57. Roth RH. Functional occlusion for the orthodontist. Part III. J Clin Orthod 1981;15:174-9, 82-98. Zachrisson BU. Important aspects of long-term stability. J Clin Orthod 1997;31:562-83. Carter GA, McNamara JA Jr. Longitudinal dental arch changes in adults. Am J Orthod Dentofacial Orthop 1998;114:88-99. Eslambolchi S, Woodside DG, Rossouw PE. A descriptive study of mandibular incisor alignment in untreated subjects. Am J Orthod Dentofacial Orthop 2008;133:343-53. Ades AG, Joondeph DR, Little RM, Chapko MK. A long-term study of the relationship of third molars to changes in the mandibular dental arch. Am J Orthod Dentofacial Orthop 1990;97:323-35. Little RM, Riedel RA, Stein A. Mandibular arch length increase during the mixed dentition: postretention evaluation of stability and relapse. Am J Orthod Dentofacial Orthop 1990;97:393-404. Little RM. Stability and relapse of dental arch alignment. Br J Orthod 1990;17:235-41. Southard TE, Southard KA, Weeda LW. Mesial force from unerupted third molars. Am J Orthod Dentofacial Orthop 1991;99:220-5. Harradine NW, Pearson MH, Toth B. The effect of extraction of third molars on late lower incisor crowding: a randomized controlled trial. Br J Orthod 1998;25:117-22. Bishara SE. Third molars: a dilemma! Or is it? Am J Orthod Dentofacial Orthop 1999;115:628-33. Sidlauskas A, Trakiniene G. Effect of the lower third molars on the lower dental arch crowding. Stomatologija 2006;8:80-4. Acar A, Alcan T, Erverdi N. Evaluation of the relationship between the anterior component of occlusal force and postretention crowding. Am J Orthod Dentofacial Orthop 2002;122:366-70. Melsen B, Dalstra M. Distal molar movement with Kloehn headgear: is it stable? Am J Orthod Dentofacial Orthop 2003;123:374-8. Janson G, Busato MC, Henriques JF, Freitas MR, Freitas LM. Alignment stability in Class II malocclusion treated with 2- and 4-premolar extraction protocols. Am J Orthod Dentofacial Orthop 2006;130:189-95.
June 2011 Vol 139 Issue 6
36. Paquette DE, Beattie JR, Johnston LE Jr. A long-term comparison of nonextraction and premolar extraction edgewise therapy in "borderline" Class II patients. Am J Orthod Dentofacial Orthop 1992;102:1-14. 37. Janson G, Maria FR, Barros SE, Freitas MR, Henriques JF. Orthodontic treatment time in 2- and 4-premolar-extraction protocols. Am J Orthod Dentofacial Orthop 2006;129:666-71. 38. Bishara SE, Bayati P, Zaher AR, Jakobsen JR. Comparisons of the dental arch changes in patients with Class II, division 1 malocclusions: extraction vs nonextraction treatments. Angle Orthod 1994; 64:351-8. 39. Bishara SE, Cummins DM, Zaher AR. Treatment and posttreatment changes in patients with Class II, Division 1 malocclusion after extraction and nonextraction treatment. Am J Orthod Dentofacial Orthop 1997;111:18-27. 40. Kahl-Nieke B, Fischbach H, Schwarze CW. Treatment and postretention changes in dental arch width dimensions—a long-term evaluation of influencing cofactors. Am J Orthod Dentofacial Orthop 1996;109:368-78. 41. Little RM, Riedel RA, Artun J. An evaluation of changes in mandibular anterior alignment from 10 to 20 years postretention. Am J Orthod Dentofacial Orthop 1988;93:423-8. 42. Ormiston JP, Huang GJ, Little RM, Decker JD, Seuk GD. Retrospective analysis of long-term stable and unstable orthodontic treatment outcomes. Am J Orthod Dentofacial Orthop 2005;128:568-74. 43. Miyazaki H, Motegi E, Yatabe K, Isshiki Y. Occlusal stability after extraction orthodontic therapy in adult and adolescent patients. Am J Orthod Dentofacial Orthop 1998;114:530-7. 44. Gianelly A. Evidence-based therapy: an orthodontic dilemma. Am J Orthod Dentofacial Orthop 2006;129:596-8. 45. Heiser W, Richter M, Niederwanger A, Neunteufel N, Kulmer S. Association of the canine guidance angle with maxillary and mandibular intercanine widths and anterior alignment relapse: extraction vs nonextraction treatment. Am J Orthod Dentofacial Orthop 2008;133:669-80. 46. BeGole EA, Fox DL, Sadowsky C. Analysis of change in arch form with premolar expansion. Am J Orthod Dentofacial Orthop 1998; 113:307-15. 47. Erdinc AE, Nanda RS, Isiksal E. Relapse of anterior crowding in patients treated with extraction and nonextraction of premolars. Am J Orthod Dentofacial Orthop 2006;129:775-84. 48. Uhde MD, Sadowsky C, BeGole EA. Long-term stability of dental relationships after orthodontic treatment. Angle Orthod 1983; 53:240-52. 49. Bishara SE, Jakobsen JR, Treder JE, Stasi MJ. Changes in the maxillary and mandibular tooth size-arch length relationship from early adolescence to early adulthood. A longitudinal study. Am J Orthod Dentofacial Orthop 1989;95:46-59. 50. Little RM, Riedel RA. Postretention evaluation of stability and relapse—mandibular arches with generalized spacing. Am J Orthod Dentofacial Orthop 1989;95:37-41. 51. Artun J, Krogstad O, Little RM. Stability of mandibular incisors following excessive proclination: a study in adults with surgically treated mandibular prognathism. Angle Orthod 1990;60:99-106. 52. Luppanapornlarp S, Johnston LE Jr. The effects of premolar extraction: a long-term comparison of outcomes in "clear-cut" extraction and nonextraction Class II patients. Angle Orthod 1993;63:257-72. 53. Sadowsky C, Schneider BJ, BeGole EA, Tahir E. Long-term stability after orthodontic treatment: nonextraction with prolonged retention. Am J Orthod Dentofacial Orthop 1994;106:243-9. 54. Harris EH, Gardner RZ, Vaden JL. A longitudinal cephalometric study of postorthodontic craniofacial changes. Am J Orthod Dentofacial Orthop 1999;115:77-82.
American Journal of Orthodontics and Dentofacial Orthopedics