The European Journal of Orthodontics Advance Access originally published online on September 12, 2008
The European Journal of Orthodontics 2008 30(5):469-476; doi:10.1093/ejo/cjn045
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Dental arch changes following rapid maxillary expansion
* Department of Orthodontics, University of Ferrara
** Consultant in Computer Science
*** Department of Economics, University of Trento, Italy
Address for correspondence Sabrina Mutinelli, Via Brennero, 260/B, 38100 Trento, Italy, E-mail: sabrinamutinelli{at}orthodontics.it
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Summary |
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The purpose of this research was to evaluate changes in upper arch dimension and form following rapid maxillary expansion (RME) using a modified Haas appliance in the primary dentition. The sample comprised 49 children [17 males, 32 females, mean age 7 years 5 months, standard deviation (SD) 1 year 1 month] with a crossbite or maxillary crowding. Twenty patients had a normal SN–GoGn angle (7 males, 13 females, mean 33.25 degrees, SD 2.10), three were low angle (1 male, 2 females, mean 27.67 degrees, SD 2.31), and 22 were high angle (8 males, 14 females, mean 39.95 degrees, SD 3.15). The vertical dimensions of four patients could not be measured, due to the unavailability of radiographs. Expansion was undertaken to either correct a crossbite or treat maxillary crowding. The upper dental casts were analysed using a computerized system: before treatment (T1), at appliance removal (T2), and 2 years 4 months after appliance removal (T3).
Using bootstrap statistical analysis applied to distance ratio values [Euclidean distance matrix analysis (EDMA)], it was found that 48 patients showed a change in arch form. In 40.82 per cent (n = 20, group A), the arch form changed from T1 to T2, T1 to T3, and T2 to T3. In 32.65 per cent (n = 16, group B), it varied from T1 to T2 but relapsed at T3 to the form of T1. For 24.5 per cent (n = 12, group C), it changed from T1 to T2 but maintained the same form at T3. The favourable characteristics for obtaining expansion, identified by logistic regression analysis, were being male, of an immature stage of dental development (lateral incisor not fully erupted) and the presence of a lateral crossbite. Intercanine and intermolar widths, arch length, and the distance between the interincisive point and the line joining the canines (depth of the intercanine arch) at the different time points were analysed using a two-tailed t-test (P < 0.05). For the whole group, the increase in intercanine and intermolar width and in the depth of the intercanine arch was significant. Comparison between groups A, B, and C was undertaken using an analysis of variance, but there was no significant difference between the groups.
This modified type of Haas appliance was able to increase the transverse dimension of the maxillary dental arch in the mixed dentition. The most appropriate timing for treatment appears to be before the eruption of the permanent lateral incisors.
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Introduction |
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Rapid maxillary expansion (RME) is a clinical technique largely employed in orthodontic treatment to manage maxillary transverse deficiencies (Kutin and Hawes, 1969
; McNamara, 2000; Schiffman and Tuncay, 2001; Petrén et al., 2003; Turpin, 2004). Many authors consider that widening of the midpalatal suture is a suitable method for treating maxillary arch size discrepancies (Haas, 1961, 1965, 1970, 1980; Wertz, 1970; Bishara and Staley, 1987; Ladner and Muhl, 1995; Spillane and McNamara, 1995; Sandikçio
lu and Hazar, 1997; McNamara, 2000; Giannelly, 2003; Sari et al., 2003; Lima et al., 2005).
The Haas appliance is one device designed to expand the palate. It is a tooth- and tissue-borne appliance attached to four teeth and to the palatal vault (Zimring and Isaacson, 1965; Haas, 1980). The screw produces orthopaedic expansion (Oliveira et al., 2004) by the activation of the midline expansion screw on a daily basis. The technique is generally considered more appropriate in young patients because the sutures are not as interdigitated as in adults (Zimring and Isaacson, 1965; Melsen, 1975; Holberg and Rudzki-Janson, 2006). However, the negative effects of applying high forces to the anchor teeth include potential root resorption (Timms and Moss, 1971; Barber and Sims, 1981; Langford and Sims, 1982; Odenrick et al, 1991; Vardimon et al., 1991, 1993) and exostoses and pulp stones (Timms and Moss, 1971). Due to these problems, Cozzani et al. (2003, 2007) evaluated the effectiveness of the Haas appliance when cemented on the primary canines and second molars and successfully achieved expansion of the upper first permanent molars.
The purpose of the present study was to evaluate the efficacy, in a group of young patients, of this modified Haas appliance in the primary dentition with respect to (1) changing the form and dimensions of the dental arch, (2) expansion stability at least 1 year out of retention, and (3) the most appropriate timing for treatment.
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Subjects and method |
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Sample
The sample comprised 49 patients (Table 1), 32 females and 17 males (mean age 7 years 5 months, SD 1 year 1 month). The children were either in the first transitional period (van der Linden and Duterloo, 1983) with the first permanent upper molars erupted (36 patients, 14 males and 22 females) or in the intertransitional period (13 patients, 3 males and 10 females).
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The vertical dimensions of 45 patients were assessed by measuring the SN–GoGn angle on lateral cephalograms taken before treatment (T1). The vertical dimension was considered to be normal if the angle measured between 30 and 36 degrees, low if the angle was less than 30 degrees, and high if the angle was more than 36 degrees. The normal angle group comprised 20 patients (7 males, 13 females; average angle 33.25 degrees, SD 2.10); the low angle group three patients (1 male, 2 females; average angle 27.67 degrees, SD 2.31), and the high angle group 22 patients (8 males, 14 females; average angle 39.95 degrees, SD 3.15). The vertical dimensions of four patients could not be measured, due to the unavailability of radiographs.
Patients required maxillary expansion for one of two reasons: in order to correct a crossbite (23 patients, 5 males and 18 females) or to treat maxillary crowding (26 patients, 12 males and 14 females).
Therapy
The patients were treated by three orthodontists, following the same protocol. A Hass appliance (Haas, 1980), modified such that it was attached to the maxillary second primary molars and primary canines, was inserted and activated once or twice per day (Figure 1). Each activation was 0.2 mm and the maximum expansion possible was 10 mm.
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The patients were monitored weekly. Expansion was terminated in the crossbite group when the first molars were in normal occlusion and, in the crowded group, when there was sufficient space for the lateral incisors (on average 20 days). The appliance was stabilized and kept in situ as retention for at least 7 months (average 11 months, SD 4 months). No direct force or any retention was applied to the permanent teeth. After RME, no additional orthodontic treatment was carried out.
For each patient study, models were taken at T1, at appliance removal (T2), and at least 1 year after appliance removal (T3; average 2 years 4 months, SD 1 year 4 months).
Dental cast analysis
The maxillary dental arches were analysed according to a previously published computerized method (Mutinelli et al., 2004). The models were scanned and the images enhanced using the software. The landmarks marked were: the interincisive point, the distal point of the right and left lateral incisor edge, the tip of the right and left canine, and the tips of the mesiobuccal cusps of the right and left first permanent molar (Figure 2). The same operator (SM) identified all landmarks, and the distances between the points were calculated automatically.
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Method error
The method error was evaluated by comparing 189 measurements repeated twice by the same operator after an interval of 1 week using the method described by Dahlberg (1948). The difference was not significant (P = 0.41).
Data elaboration and statistical analysis
Evaluation of dental arch form change.
The distances between the points were analysed using Euclidean distance matrix analysis (EDMA; Lele and Richtsmeier, 1991; Ferrario et al., 1994; Cole and Richtsmeier, 1998) and the statistical bootstrapping technique (Efron and Tibshirani, 1993) in order to investigate the change in arch form between the different time points: from T1 to T2 (expansion), from T2 to T3 (relapse), and from T1 to T3 (final expansion out of retention).
Using this method, it was first necessary to determine whether the average of the observations for a single patient was significantly different from 1. An observation is given by the ratio of a particular measurement at each of the different time points, T1, T2, and T3. Hence, for each measurement and each patient, three ratios were calculated: DT2/DT1, DT3/DT1, and DT3/DT2 (EDMA). There were 21 observations for each patient (although in a small number of cases some of the measurements were missing, so that the observations were fewer than 21). A bootstrap analysis, which is a computer-based statistical method (Efron and Tibshirani, 1993), was run for each patient and for each of the three combinations of times: (T2/T1, T3/T1, and T3/T2). The confidence interval (CI, 95 per cent) of a predicted value was determined following duplication of the sample using 1000 iterations. Therefore, CIs were generated using the bootstrap method for the 21 measurements and the data studied to ascertain whether the value 1 was included in the interval: if the answer was positive, it was concluded that the distance was unchanged, otherwise the hypothesis that the distance was unchanged was rejected.
The patients were then divided into three groups based on the change in shape of the dental arch:
- 1. Group A (variability): the form changed from T1 to T2, from T2 to T3, and from T1 to T3.
- 2. Group B (relapse): the form changed from T1 to T2, from T2 to T3, but at T3 it was the same as at T1.
- 3. Group C (stability): the form changed from T1 to T2, from T1 to T3, but at T3 it was the same as at T2.
- 2. Group B (relapse): the form changed from T1 to T2, from T2 to T3, but at T3 it was the same as at T1.
In order to further investigate the change in the arch form and establish why group C was more stable, logistic regression was undertaken with the following variables included: gender, presence or absence of a lateral crossbite, dental age (presence or absence of all four permanent incisors), and vertical dimension.
Evaluation of the transverse and sagittal dimensions. A two-tailed t-test (P < 0.05) was used to investigate intercanine and intermolar widths, arch length (distance between the interincisive point and intermolar width), and intercanine arch depth (distance between the interincisive point and the line joining the canines) measured at the different time points (Figure 3). For each group of measurements, the 95 per cent CI for the mean was calculated and groups A, B, and C were compared using an analysis of variance (ANOVA).
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The analyses provided values for the whole sample and for the eight subsamples classified according to gender, presence or absence of a lateral crossbite, dental age, and vertical dimension at the start of treatment: (1) male group, (2) female group, (3) crossbite group, (4) non-crossbite group, (5) early dental age group, i.e. patients with lateral incisor eruption not yet complete (first transitional period), (6) late dental age group, i.e. patients with four permanent incisors (intertransitional period), (7) high angle group, and (8) normal angle group.
When analysing the vertical dimension groups, the low angle group was not considered because of the small number of subjects (n = 3).
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Results |
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Arch form variation
The results of the analyses are shown in Table 1. One patient could not be classified because the arch form only changed from T2 to T3.
The coefficients for arch form stability after expansion, calculated using logistic regression, were dental age 2.3433 (P < 0.001), vertical dimension 0.0055 (P = 0.94), lateral crossbite –2.1287 (P < 0.001), and gender –0.1552 (P = 0.0304).
The coefficients showed that vertical dimension did not affect stability following upper arch expansion, whereas early dental age, a lateral crossbite, and male gender were statistically significant factors in obtaining stable expansion out of retention. The probabilities of relapse are shown in Table 2.
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Arch width and length variation
Whole group.
Intercanine and intermolar width.
The variations were significant (P < 0.05) from T1 to T2 (intercanine width 5.04 mm, SD 1.87; intermolar width 3.63 mm, SD 1.97) and from T1 to T3 (intercanine width 2.97 mm, SD 2.18; intermolar width 2.58 mm, SD 2.17). The measurements increased as a result of RME and then later relapsed (relapse of intercanine width 2.08 mm, SD 2.26; relapse of intermolar width 1.05 mm, SD 1.54); however, the final values, measured 2 years 4 months out of retention, remained significantly increased (Table 3).
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Arch length and intercanine arch depth.
Arch length increased significantly (P < 0.05) from T1 to T2 (1.03 mm, SD 1.33) and then decreased from T2 to T3 (0.58 mm, SD 1.19). Although the T3 value was greater than that at T1, there was no significant difference between the T1 and T3 measurements (increase from T1 to T3 of 0.44 mm, SD 1.45). Intercanine arch depth increased from T2 to T3 (T2 to T3 0.81 mm, SD 1.14; ns from T1 to T2 0.10 mm, SD 1.21; Table 3).
Intercanine and intermolar width in the subgroups
Crossbite and non-crossbite group. The only significant difference between the two groups was for intermolar width (Table 4) which was increased in the group with a lateral crossbite (crossbite group at T2 4.87 mm, SD 1.37 and non-crossbite group 2.56 mm, SD 1.81; T3: 3.85 mm, SD 1.57 and 1.37 mm, SD 2.01, respectively). However, the extent of the relapse was similar for the two groups (–1.02 mm, SD 1.40, versus –1.19 mm, SD 1.61).
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Age/dental development. The group was divided into two subgroups with respect to the presence (late dental age) or absence (early dental age) of the permanent lateral incisors. The increase and relapse measured in the intercanine and intermolar widths were significant in both subsamples.
Comparing the two groups at T1, the intercanine width of the younger patients was significantly less (28.64 mm, SD 2.66) than for the older group (31.43 mm, SD 2.97). At T3, intercanine width showed a non-significant difference between the subgroups (32.11 mm, SD 2.55, and 33.10 mm, SD 1.58, respectively).
Therefore, the intercanine width expanded more before eruption of the permanent lateral incisors than after. At T3, the two groups relapsed in the same way although with a resultant greater net increase in arch width in the younger patients.
The increase in intercanine arch depth and arch length was significantly larger in the group expanded before eruption of the permanent lateral incisors.
High and normal angle group.
Expansion at T2, and relapse at T3, of the intercanine and intermolar widths respectively in the high angle group were significant. Comparison of the same widths between the two subsamples was not significant.
Female and male groups.
The increase (T2), and relapse (T3), of the intercanine and intermolar widths were significant. Comparison between males and females showed that the change in intercanine and intermolar widths was approximately the same in both groups.
Groups A, B, and C.
The expansion, relapse, and net increase at T3 were significant in groups A and B. In group C, the changes were significant, but the relapse was not significant. Comparing the groups using ANOVA, the results were not significant.
Arch length and intercanine arch depth variation in the subgroups
Intercanine arch depth tended to increase slightly after expansion in all subgroups, with the exception of the older dental age group and group B, where there was a decrease in arch length and a non-significant change in intercanine arch depth (Table 5).
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Discussion |
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TopSummaryIntroductionSubjects and methodResultsDiscussionConclusionsReferences |
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In this study, expansion resulted in arch form changes in 98 per cent of the patients. Study model analysis showed that RME acted on the transverse dimension and did not affect the sagittal dimensions of the dental arch.
The intercanine and intermolar widths increased during expansion and a significant amount of this expansion was retained more than 2 years out of retention, confirming the efficacy of the Haas appliance when anchored to the primary canines and primary molars. The effectiveness of the Haas appliance has been demonstrated by others, but with the device anchored to the permanent teeth (Ladner and Muhl, 1995; Moussa et al., 1995; Spillane and McNamara, 1995; Sandikçiolu and Hazar, 1997; Sari et al., 2003; Oliveira et al., 2004; Lima et al., 2005). Cozza et al. (2001) successfully used an expander banded to the second primary molars, but it was a butterfly type without an acrylic palatal button.
The expansion of the intercanine width was greater than that in the intermolar area: e.g. in group C, at T2, the intercanine width expanded 1.4 times more than the intermolar width. This could be explained by the triangular opening of the palatal suture due to the position of the centre of resistance of the maxilla with respect to the screw position (Wertz, 1970; da Silva Filho et al., 1995; Lee et al., 1997; Moore, 1997; Vardimon et al., 1998; Braun et al., 1999; Davidovitch et al., 2005).
The dental arch showed a tendency for intercanine arch depth to increase after expansion. Analysis of the change in intercanine arch depth with respect to dental age at T3 showed that the group expanded before the eruption of the permanent lateral incisors had a significant increase from T2 to T3, whereas the older group (with erupted permanent lateral incisors) did not show any change in intercanine arch depth.
Growth linked to dental eruption has been suggested as a predictive factor for the success of arch expansion. Sillman (1964), Moorrees et al. (1969), and van der Linden and Duterloo (1983) explained the change as a result of buccal proclination of the permanent incisors with respect to the primary teeth.
After computation of the variation in arch form with EDMA and bootstrapping, the patients were classified into three subsamples. Group C showed little relapse between the three observational points and was therefore considered to be ‘stable’. Using logistic regression, three pre-treatment characteristics appear to be important factors to obtain stable expansion: the presence of a posterior crossbite, dental age, and being male.
Spillane and McNamara (1995) did not find any relationship between expansion and age or between expansion and a posterior crossbite. However, they used an acrylic bonded expander, and the methods of evaluation were different from the present study.
The first predictive characteristic for stability was a posterior crossbite. The intermolar width increased more in the crossbite group, but relapse was equal for both subsamples. The initial width in the crossbite group was significantly less than that in the group with a normal transverse relationship. After expansion, this difference was no longer apparent. This behaviour was similar to that observed in the variation of the intercanine width found in the two different dental age groups.
The second predictive characteristic for stability was dental age. Subjects in the early dental age group showed an increase in intercanine arch depth. In group C (stable), this increase compensated for the reduction in arch length in the region of the primary molars and first permanent molar. Therefore, at T3 arch length was unchanged. Some authors have explained this reduction in length of the molar area as being a consequence of space closure between the primary molars (Sillman, 1964; Moorrees et al., 1969; van der Linden and Duterloo, 1983). Evaluation of the intercanine width in the younger (first transitional period) and older (intertransitional period) patients before expansion showed a significantly lower value in the first group. After expansion there was no significant difference: the increase in the younger children was greater but the relapse was the same in both groups. Dental age did not affect expansion of the intermolar distance.
It is also important to consider how much of the increase in intercanine width is due to growth and how much to RME. The increase in intercanine width during growth has been analysed by many authors. Sillman (1964), Knott (1972), and Bishara et al. (1997) noted an increase in the intercanine width until 13 years. Moorrees et al. (1969) and van der Linden and Duterloo (1983) reported a significant increase in intercanine width during the eruption of the permanent incisors and a further small increase as the permanent canines erupt. Sinclair and Little (1983) found a significant decrease from the mixed dentition stage into early adulthood; however, the mixed dentition stage in that research corresponded with both the intertransitional and the second transitional periods.
Therefore, it is possible that upper intercanine width increases between the intertransitional and second transitional periods. Consequently, there may be additional space created by growth, as well as by early treatment with RME. However, Schiffman and Tuncay (2001), in a meta-analysis, found no data to support the hypothesis that space can be gained in the dental arch in addition to the increase produced by normal growth, even if the maxilla has been expanded. Comparing the results of the two studies, the short-term post-expansion intermolar data were similar: 75 per cent in the meta-analysis (Schiffman and Tuncay, 2001) and 71 per cent in the present investigation. However, in the meta-analysis the average age of the patients was older than that in the present study and the effect of expansion was evaluated only by the change in intermolar width. Therefore, the increase found in the present investigation in younger patients may be due to the appliance producing earlier growth in the intercanine area.
In contrast to the work by Spillane and McNamara (1995) and Lima et al. (2005), there was a significant difference (P < 0.05) in stability between males and females in the present study.
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Conclusions |
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TopSummaryIntroductionSubjects and methodResultsDiscussionConclusionsReferences |
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Expansion of the maxilla using a Haas appliance anchored to the primary teeth resulted in a significant increase in transverse width. The most stable result was in younger patients (first transitional period) with a lateral crossbite. Therefore, when presented with the choice of treating early or postponing expansion, it may be better to commence therapy before eruption of the permanent lateral incisors. In addition, at this dental age it is possible to band the second primary molars, without involving the permanent dentition and this consequently avoids the risk of damage to these teeth. Moreover, with favourable growth the intercanine arch width may increase until eruption of the permanent canines, resulting in a widening of the anterior part of the arch.
Further, long-term studies are necessary to evaluate the ‘real’ amount of intercanine growth after expansion and to confirm the greater stability of the results obtained in younger patients.
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References |
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Barber AF, Sims MR. Rapid maxillary expansion and external root resorption in man: a scanning electron microscope study. American Journal of Orthodontics (1981) 79:630–652.[CrossRef][Web of Science][Medline]
Bishara SE, Staley RN. Maxillary expansion: clinical implication. American Journal of Orthodontics and Dentofacial Orthopedics (1987) 91:3–14.[CrossRef][Web of Science][Medline]
Bishara SE, Jakobsen JR, Treder J, Nowak A. Arch width changes from 6 weeks to 45 years of age. American Journal of Orthodontics and Dentofacial Orthopedics (1997) 111:401–409.[CrossRef][Web of Science][Medline]
Braun S, Lee K-G, Legan HL. A reexamination of various extraoral appliances in light of recent research findings. Angle Orthodontist (1999) 69:81–84.[Web of Science][Medline]
Cole M, Richtsmeier JT. A simple method for visualization of influential landmarks when using Euclidean distance matrix analysis. American Journal of Physical Anthropology (1998) 107:273–283.[CrossRef][Web of Science][Medline]
Cozza P, Giancotti A, Petrosino A. Rapid palatal expansion in mixed dentition using a modified expander: a cephalometric investigation. Journal of Orthodontics (2001) 28:129–134.
Cozzani M, Rosa M, Cozzani P, Siciliani G. Deciduous dentition-anchored rapid maxillary expansion in crossbite and non-crossbite mixed dentition patients: reaction of the permanent first molar. Progress in Orthodontics (2003) 4:15–22.[CrossRef][Medline]
Cozzani M, Guiducci A, Mirenghi S, Mutinelli S, Siciliani G. Arch width change with a rapid maxillary expansion appliance anchored to the primary teeth. Angle Orthodontist (2007) 77:296–302.[CrossRef][Web of Science][Medline]
Dahlberg G. Statistical methods for medical and biological students (1948) London: George Allen and Unwin Ltd.
da Silva Filho OG, do Prado Montes LA, Torelly LF. Rapid maxillary expansion in the deciduous and mixed dentition evaluated through posteroanterior cephalometric analysis. American Journal of Orthodontics and Dentofacial Orthopedics (1995) 107:268–275.[CrossRef][Web of Science][Medline]
Davidovitch M, Efstathiou S, Sarne O, Vardimon AD. Skeletal and dental response to rapid maxillary expansion with 2- versus 4-band appliances. American Journal of Orthodontics and Dentofacial Orthopedics (2005) 127:483–492.[CrossRef][Web of Science][Medline]
Efron B, Tibshirani R. An introduction to the bootstrap (1993) London: Chapman and Hall.
Ferrario VF, Sforza C, Miani A, Tartaglia G. Maxillary versus mandibular arch form differences in human permanent dentition assessed by Euclidean-distance matrix analysis. Archives of Oral Biology (1994) 39:135–139.[CrossRef][Web of Science][Medline]
Giannelly A. Rapid maxillary expansion in absence of crossbites: added value? American Journal of Orthodontics and Dentofacial Orthopedics (2003) 124:362–365.[CrossRef][Web of Science][Medline]
Haas JA. Rapid expansion of the maxillary dental arch and nasal cavity by opening the midpalatal suture. Angle Orthodontist (1961) 31:73–90.
Haas JA. The treatment of maxillary deficiency by opening the midpalatal suture. Angle Orthodontist (1965) 35:200–217.[Medline]
Haas JA. Palatal expansion: just the beginning of dentofacial orthopedics. American Journal of Orthodontics (1970) 57:219–255.[CrossRef][Web of Science][Medline]
Haas JA. Long-term posttreatment evaluation of rapid palatal expansion. Angle Orthodontist (1980) 50:189–217.[Web of Science][Medline]
Holberg C, Rudzki-Janson I. Stresses at the cranial base induced by rapid maxillary expansion. Angle Orthodontist (2006) 76:543–550.[Web of Science][Medline]
Knott V. Longitudinal study of dental arch widths at four stages of dentition. Angle Orthodontist (1972) 42:387–394.[Web of Science][Medline]
Kutin G, Hawes RR. Posterior cross-bites in the deciduous and mixed dentitions. American Journal of Orthodontics (1969) 56:491–504.[CrossRef][Web of Science][Medline]
Ladner PT, Muhl ZF. Changes concurrent with orthodontic treatment when maxillary expansion is a primary goal. American Journal of Orthodontics and Dentofacial Orthopedics (1995) 108:184–193.[CrossRef][Web of Science][Medline]
Langford SR, Sims MR. Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man. American Journal of Orthodontics (1982) 81:108–115.[CrossRef][Web of Science][Medline]
Lee K-G, Ryu Y-K, Park Y-C, Rudolph DJ. A study of holographic interferometry on the initial reaction of maxillofacial complex during protraction. American Journal of Orthodontics and Dentofacial Orthopedics (1997) 111:623–632.[CrossRef][Web of Science][Medline]
Lele S, Richtsmeier JT. Euclidean distance matrix analysis: a coordinate-free approach for comparing biological shapes using landmark data. American Journal of Physical Anthropology (1991) 86:415–427.[CrossRef][Web of Science][Medline]
Lima AL, Lima Filho RMA, Bolognese AM. Long-term clinical outcome of rapid maxillary expansion as the only treatment performed in Class I malocclusion. Angle Orthodontist (2005) 75:416–420.[Web of Science][Medline]
McNamara J. Maxillary transverse deficiency. American Journal of Orthodontics and Dentofacial Orthopedics (2000) 117:567–570.[CrossRef][Web of Science][Medline]
Melsen B. Palatal growth studied on human autopsy material. A histologic microradiographic study. American Journal of Orthodontics (1975) 68:42–54.[Web of Science][Medline]
Moore RN. Principles of dentofacial orthopedics. Seminars in Orthodontics (1997) 3:212–222.[CrossRef][Medline]
Moorrees CFA, Grøn A-M, Lebret LML, Yen PKJ, Fröhlich FJ. Growth studies of the dentition: a review. American Journal of Orthodontics (1969) 55:600–616.[CrossRef][Web of Science][Medline]
Moussa R, O’Reilly MT, Close JM. Long-term stability of rapid palatal expander treatment and edgewise mechanotherapy. American Journal of Orthodontics and Dentofacial Orthopedics (1995) 108:478–488.[CrossRef][Web of Science][Medline]
Mutinelli S, Cozzani M, Manfredi M, Siciliani G. Dental arch analysis system. Progress in Orthodontics (2004) 5:200–208.[Medline]
Odenrick L, Karlander EL, Pierce A, Kretschmar U. Surface resorption following two forms of rapid maxillary expansion. European Journal of Orthodontics (1991) 13:264–270.
Oliveira NL, Da Silveira AC, Kusnoto B, Viana G. Three-dimensional assessment of morphologic changes of the maxilla: a comparison of 2 kinds of palatal expanders. American Journal of Orthodontics and Dentofacial Orthopedics (2004) 126:354–362.[CrossRef][Web of Science][Medline]
Petrén S, Bondemark L, Söderfeldt B. A systematic review concerning early orthodontic treatment of unilateral crossbite. Angle Orthodontist (2003) 73:588–596.[Web of Science][Medline]
Sandikçiolu M, Hazar S. Skeletal and dental changes after maxillary expansion in the mixed dentition. American Journal of Orthodontics and Dentofacial Orthopedics (1997) 111:321–327.[CrossRef][Web of Science][Medline]
Sari Z, Uysal T, Usumez S, Basciftci FA. Rapid maxillary expansion. Is it better in the mixed or in the permanent dentition? Angle Orthodontist (2003) 73:654–661.[Web of Science][Medline]
Schiffman PH, Tuncay OC. Maxillary expansion: a meta analysis. Clinical Orthodontics Research (2001) 4:86–96.[CrossRef]
Sillman JH. Dimensional changes of the dental arches: longitudinal study from birth to 25 years. American Journal of Orthodontics (1964) 50:824–842.[CrossRef][Web of Science]
Sinclair PM, Little RM. Maturation of untreated normal occlusion. American Journal of Orthodontics (1983) 83:114–123.[CrossRef][Web of Science][Medline]
Spillane LM, McNamara JA. Maxillary adaptation to expansion in the mixed dentition. Seminars in Orthodontics (1995) 1:176–187.[CrossRef][Medline]
Timms DJ, Moss JP. An historical investigation into the effect of rapid maxillary expansion on the teeth and their supporting tissues. Transactions of the European Orthodontic Society (1971) 263–272.
Turpin DL. Dealing with posterior crossbite in young patients. American Journal of Orthodontics and Dentofacial Orthopedics (2004) 126:531–532. (editorial).[CrossRef][Web of Science][Medline]
van der Linden FPGM, Duterloo HS. Development of the dentition (1983) Chicago: Quintessence Publishing Co.
Vardimon AD, Graber TM, Voss LR, Lenke J. Determinants controlling iatrogenic external root resorption and repair during and after palatal expansion. Angle Orthodontist (1991) 61:113–122.[Web of Science][Medline]
Vardimon AD, Graber TM, Pitaru S. Repair process of external root resorption subsequent to palatal expansion treatment. American Journal of Orthodontics and Dentofacial Orthopedics (1993) 103:120–130.[CrossRef][Web of Science][Medline]
Vardimon AD, Brosh T, Spiegler A, Liberman M, Pitaru S. Rapid palatal expansion: Part 1. Mineralization pattern of the midpalatal suture in cats. American Journal of Orthodontics and Dentofacial Orthopedics (1998) 113:371–378.[Web of Science][Medline]
Wertz RA. Skeletal and dental changes accompanying rapid midpalatal suture opening. American Journal of Orthodontics (1970) 58:41–66.[CrossRef][Web of Science][Medline]
Zimring JF, Isaacson RJ. Forces produced by rapid maxillary expansion. Angle Orthodontist (1965) 35:178–186.[Medline]
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