Arch Width Changes Research Articles

Maxillary arch width and buccal corridor changes with orthodontic treatment. Part 2: Attractiveness of the frontal facial smile in extraction and nonextraction outcomes

This study was designed to assess the influence that the buccal corridor might have on the frontal facial attractiveness of subjects who had received orthodontic treatment with or without 4 premolar extractions. Posttreatment full-face frontal smiling photographs of 30 premolar extraction and 27 nonextraction patients were evaluated by 20 orthodontists, 20 dentists, and 20 laypeople using a visual analog scale. The ratings were analyzed according to rater group, rater sex, and number of years in practice for orthodontists and dentists to search for any statistically significant differences in the ratings on the basis of treatment groups, subject sex, and buccal corridor widths and areas. Orthodontists and dentists gave higher mean overall frontal facial attractiveness scores than did laypeople. There were no significant differences in how men and women rated the study subjects. The number of years in practice did not affect how the orthodontists rated, but it did affect the ratings of the dentists. Female subjects were consistently rated as significantly more attractive than male subjects. There was no difference in ratings for the extraction and nonextraction subject groups. The buccal corridor widths and areas did not affect the frontal facial attractiveness ratings. If treatment has been carried out with thorough diagnosis and careful planning, neither the choice of extraction or nonextraction treatment, nor the resulting buccal corridor widths or areas appeared to affect the subjects' frontal facial attractiveness.

Maxillary arch width and buccal corridor changes with orthodontic treatment. Part 1: Differences between premolar extraction and nonextraction treatment outcomes

In this retrospective study, we examined and compared the pretreatment and posttreatment arch widths and buccal corridor changes in subjects who had received orthodontic treatment either with or without premolar extractions. Pretreatment and posttreatment casts, frontal smiling photographs, and lateral cephalograms of 30 extraction and 27 nonextraction patients were analyzed to determine any significant differences in arch widths, buccopalatal inclinations of the teeth, and buccal corridor widths and areas, both within and between the 2 groups. Relationships between buccal corridor measurements and corresponding arch widths and buccopalatal inclinations of the teeth were also examined. There was a significant increase in the posttreatment maxillary intercanine width in the extraction group but not in the nonextraction group. Both the pretreatment and posttreatment arch widths between the maxillary first molars and at the level of the posterior rugae were greater in the nonextraction group than in the extraction group. There were no significant differences in any buccal corridor widths or areas measured between the extraction and nonextraction subjects. Because they reflect different morphologies, there are likely to be significant differences in average maxillary anterior and posterior posttreatment arch widths in those treated with or without extractions. However, these arch width differences are not likely to be discernible in extraction and nonextraction patients as differences in the buccal corridor widths and areas.

Incisor Inclination and Arch Width Changes Following Mandibular Setback Surgery for Correction of Mandibular Prognathism

Purpose: The aim of this study was to investigate and evaluate the changes of incisor inclination and arch width in the surgical-orthodontic treatment to correct a Class Ⅲ malocclusion resulting from skeletal mandibular prognathism. Materials and methods: The skeletal mandibular prognathism subjects consisted of 25 males and 20 females (mean age:22.8±4.2years). A lateral cephalogram was taken for each subject before preoperative orthodontic treatment (T1), presurgical (T2), and at completion of the postoperative orthodontic treatment (T3). Skeletal and dental values and arch width measurements at T1, T2 and T3 were obtained. Each cephalogram was traced and digitized twice. For statistical evaluation, all the data were expressed as Mean±Standard deviation and analyzed with SPSS software. Results: At pretreatment, dental compensation was normally found in both dental arches, including anterior and posterior teeth. During presurgical orthodontic treatment, most of the patient’s mandibular incisors were significantly decompensated (P<0.05), while no significant changes were noted in the maxillary incisors (P ≥ 0.05). The increase in maxillary inter-first molar width were statistically significant (P<0.05). With effective dental decompensation, the relationship between teeth and basal bone was improved obviously. It is beneficial for moving bone bulk in surgery. After the surgery, most of the patients (97.8%) finished with proper overjet and overbite, establish stable and harmony occlusion. Conclusion: By effective and proper dental decompensation, desired teeth positions could be achieved before surgery, which could lead to better surgical results.

Thirty-two-year follow-up study of Herbst therapy: A biometric dental cast analysis

The aim of this study was to analyze the very long-term effects of Herbst treatment on toothposition and occlusion. Fourteen patients from a sample of 22 with Class II Division 1 malocclusions consecutively treated with the banded Herbst appliance were reexamined 32 years after therapy. Dental casts were analyzed from before (T1) and after (T2) treatment, and at 6 years (T3) and 32 years (T4) after treatment. Minor changes in maxillary and mandibular dental arch perimeters and arch widths were seen during treatment (T1-T2) and posttreatment (T2-T4). Mandibular incisor irregularity remained, on average, unchanged from T1 to T2 but increased continuously during the 32-year follow-up period (T2-T4). Class II molar and canine relationships were normalized in most patients from T1 to T2. During the early posttreatment period (T2-T3), there was a minor relapse; during the late posttreatment period (T3-T4), molar and canine relationships remained, on average, unchanged. Overjet and overbite were reduced to normal values in all subjects during treatment (T1-T2). After treatment (T2-T4), overjet remained, on average, unchanged, but overbite increased insignificantly. Thirty-two years after Herbst therapy, overall, acceptable long-term results were seen. Stability was found in 64% of the patients for sagittal molar relationships, in 14% for sagittal canine relationships, in 86% for overjet, and in 86% for overbite. A Class II relapse seemed to be caused by an unstable interdigitation of the occluding teeth, a persisting oral habit, or an insufficient retention regimen after treatment. Most posttreatment changes occurred during the first 6 years after treatment. After the age of 20 years, only minor changes were noted. Long-term posttreatment changes in maxillary and mandibular dental arch perimeters and widths as well as in mandibular incisor irregularity seemed to be independent of treatment and a result of physiologic dentoskeletal changes throughout adulthood.

Space supervision and guidance of eruption in management of lower transitional crowding: A non-extraction approach

Mandibular incisor crowding in the mixed dentition is one of the most common problems presenting to the orthodontist. Asymmetry of alignment, premature loss of primary canine(s), and disruption in arch integrity are all early benchmarks of a tooth size/arch length discrepancy in the transitional dentition that can occur independent of any skeletal discrepancy. Space supervision and guidance of eruption refer to treatment interventions during the early to mid-mixed dentition periods that influence the eruption patterns and positioning of the permanent teeth during their transition. Generally considered applicable to individuals with adequate overall arch dimensions to accommodate a normal complement of permanent teeth with an acceptable esthetic and functioning occlusion, guidance of eruption involves the implementation of directed interventions to optimize the eruption and alignment patterns of the permanent teeth as part of a non-extraction protocol.

Dentoalveolar changes following maxillary distraction osteogenesis

The purpose of this study was to compare the dentoalveolar changes produced when using two different intraoperative surgical procedures for maxillary distraction osteogenesis. Eight patients were assigned into two groups according to the surgical procedure: down-fracture (DF, n = 6) vs non-down-fracture (NDF, n = 2). Lateral cephalograms and 3-D models before and after maxillary distraction were analyzed. The Mann-Whitney U test was used to compare the differences in the amounts of advancement and dento-alveolar changes between the DF and NDF groups. The significance level was established at 0.05. Although a significantly greater amount of maxillary movement was observed in the DF group (10.0 mm ± 2.2) than in the NDF group (5.9 mm ± 2.3), significantly greater arch length (8.7 mm ± 5.2) and arch width changes (6.0 mm ± 1.0) were observed in the NDF group than in the DF group, (arch lengths 3.0 mm ± 1.1 and arch width changes 3.2 mm ± 2.0). A significantly greater amount of dental anchorage loss was observed in the NDF group. The use of the NDF procedure resulted in greater amounts of dental anchorage loss than resulted from the DF procedures when tooth-borne devices were used during maxillary distraction osteogenesis. The type of surgical procedure might play an important role in the amount and direction of the dental changes.

Arch Widths after Extraction and Nonextraction Treatment in Class I Patients

To compare pretreatment and post-treatment dental arches in relation to intercanine and intermolar width changes in extraction and nonextraction treatment in class I patients. In this retrospective study pretreatment and post-treatment dental casts of 60 patients (30 extractions of first premolars and 30 nonextractions) were selected. Anterior and posterior arch widths in the canine and molar regions from the most labial aspect of buccal surfaces, the canines and the molars were measured with the help of digital caliper on the study models and compared statistically to determine whether the dental arches were narrower after extraction treatment. At the start of the treatment there were no statistically significant differences in maxillary and mandibular intercanine widths in both groups. At the end of treatment in both the groups anterior and posterior arch width changes were not significant except for the intercanine dimension which was 0.82 mm larger (p < 0.05) in the extraction group. The extraction treatment does not result in narrower dental arches than nonextraction treatment in intercanine and intermolar region. It is documented that the arch widths determine smile esthetics and treatment stability. According to the findings of the present study the arch widths in extraction treatments are not narrower than nonextraction so there will not be any compromising effects on esthetics and treatment stability.

Premaxillary characteristics in complete bilateral cleft lip and palate: A predictor for treatment outcome

Objectives:The aim of the current study was to investigate how bilateral cleft lip and palate (BCLP) cases responded differently to presurgical orthopedics (PSO) and primary lip repair (LR) based on premaxillary characteristics. We suggest a clinically oriented descriptive classification for BCLP based on premaxillary characteristics.Design and Setting:A retrospective longitudinal comparative study where available records of all non-syndromic patients with complete BCLP attending the Cleft Clinic, affiliated to the Oral and Maxillofacial Surgery department, Ain-Shams University, Cairo, Egypt were assessed.Sample Population and Methodology:Twenty-two cases were collected over a 4-years period from 2008 to 2011 (15 boys and 7 girls). Model assessment was performed for serial models representing four stages of treatment; M1: Prior to start of PSO, M2: At the end of PSO, M3: One month after LR, M4: Three months after LR. The premaxillary and vomerine widths were measured on M1. Models (M1-M4) were assessed for changes in anteroposterior projection, anterior arch width, intercanine width and posterior arch width and results were statistically analyzed. Intra-and postoperative surgical findings during and after primary LR were recorded. The sample was divided into two groups based on the premaxillary size and characteristics; Group R: Rudimentary premaxilla and Group P: Prominent premaxilla.Results:There was a highly significant difference in premaxillary width between the two groups (P = 0.00), changes in anteroposterior projection of the premaxilla were significant one and three months after LR. Changes in maxillary anterior arch width, intercanine and posterior arch widths were non-significant between groups. Mean age difference between the two groups was only statistically significant at the stage of LR. Surgical differences were noted between the two groups. Postoperatively as compared to group R; group P showed more premaxillary bulge and show at rest, as well as more prolabial stretching. In addition, facial profile was more convex in group P.Conclusion:The two types of BCLP outlined in this study are different from several aspects, and hence management should be modified according to each case. This descriptive classification provides a useful tool for evaluation and planning of patients with BCLP.

Facial divergence and mandibular crowding in treated subjects.

To understand the relationships between facial divergence, vertical growth, and postretention mandibular crowding. Seventy-five white extraction patients were evaluated immediately posttreatment (15.4 years) and again 16.6 years later. Hyperdivergent subjects, subjects with open bite or severe deep bites were not evaluated. Changes in incisor irregularity and tooth-size arch-length discrepancies (TSALD) were evaluated and correlated with measures of divergence and skeletal growth. Incisor irregularity increased 0.9 mm and TSALD increased 0.7 mm after treatment; 68% of the subjects had less than 3.5 mm incisor irregularity at postretention. Male patients showed significantly more growth than female patients did. Female patients, who were significantly more hyperdivergent than male patients, showed weak to moderately weak associations between posttreatment facial divergence and crowding. Female posttreatment changes in anterior face height, lower incisor eruption, and changes in arch depth were also related to crowding; male patients showed moderate relationships between posttreatment changes in arch width and crowding. Greater vertical growth, incisor eruption, and especially facial divergence are related to greater posttreatment mandibular crowding.

Changes in dental and basal archforms with preformed and customized archwires during orthodontic treatment

ObjectivesTo evaluate changes to the dental and dentoalveolar (WALA Ridge) arch widths with preformed and customized archwires during orthodontic treatment. Methods20 patients treated with preformed archwires and 20 treated with customized archwires were recruited. Pre-treatment (T1) and post-treatment (T2) mandibular casts were used to determine the changes in dental and dentoalveolar arch width measured at the canine, premolar and molar areas. Ratios of transverse dental to dentoalveolar movements were also calculated. Results were compared to an untreated control group with mandibular casts taken at two comparable time points. Data were analyzed using ANOVA and t-test. ResultsSignificant changes in dental and dentoalveolar arch width were found with the preformed archwire group when compared to the control (p<0.05). However, no significant changes in dental and dentoalveolar arch width were found with the customized archwire group compared to the control. Significant correlations were found between the dental and dentoalveolar arch widths. However, the ratios of dental to dentoalveolar transverse change differed between the groups and indicated that the types of movements were contrasting between the preformed and custom arch forms as each expanded the dental arches. ConclusionsThe WALA Ridge is a stable landmark when archwires are customized or shaped to the WALA Ridge. Changes in the WALA Ridge are expected when preformed archwires are used which do not conform to the patient's dentoalveolar arch width defined by the WALA Ridge. This is probably accounted for by the different types of tipping combined with extrusion that both methods employ.

Do long-term changes in relative maxillary arch width affect buccal-corridor ratios in extraction and nonextraction treatment?

Our aims were to evaluate long-term maxillary arch width changes in orthodontic patients treated with and without premolar extractions and to provide a potential link to the buccal-corridor ratios. Dental casts of 34 extraction and 32 nonextraction orthodontic patients with Class I malocclusions were digitized and evaluated before treatment (T1), at posttreatment (T2), and at postretention (T3). The mean postretention times for the extraction and the nonextraction groups were 5 years 2 months and 4 years 10 months, respectively. Specific arch width measurements were made on the anatomic y-axis of the casts between the most labial aspects of the anatomic dental arch immediately distal to the incisive papilla, the farthest point posteriorly of the conjunction of the third lateral and medial rugae on the midpalatal raphe and at an individually constant distance from the incisive papilla. Arch width changes were calculated and compared statistically to determine whether the dental arches were narrower after extraction treatment and at postretention. All maxillary arch width measurements remained virtually stable after extraction therapy and at the postretention follow-up. Significant increases were recorded for all maxillary arch width measurements in the nonextraction group after treatment (mean changes, 1.37-2.05 mm). Posterior arch width measurements decreased significantly between T2 and T3 (mean change, 0.5 mm). Mean changes between T1 and T2 were significant between the 2 groups for all measurements (P<0.05). Only the mean change in posterior arch width was significant between the 2 groups in the postretention period (P<0.05). Extraction treatment did not result in narrower maxillary dental arches, whereas nonextraction treatment slightly expanded the dental arch.

A Prospective Clinical Trial of Arch Width Changes Evaluated through Dental Casts in Consecutively Treated Non-extraction and Extraction Cases

Objective: To compare the dental arch width changes in consecutively treated extraction and non-extraction Class I patients. Materials and methods: Anterior and posterior arch widths of the maxillary and mandibular arches of 21 patients treated by 4 first-premolar extraction and 20 patients treated without extractions were measured on study models using a digital caliper.The initial mean ages were 13.4 ± 1.02 years for the extraction group and 13.1 ± 1.7 years for the non-extraction group. Mean treatment time was 2.7 ± 0.6 years for the extraction group and 2.4 ± 1.0 years for the non-extraction group. The maxillary and mandibular crowding were −5.2 ± 2.8 and −5.9 ± 3.1 mm for the extraction group and −4.1 ± 2.7 and −3.3 ± 2.5 mm for the non-extraction group, respectively. To compare the changes between groups, independent samples t-tests were performed. Results: At the end of treatment, no differences were found between the groups in maxillary intercanine width. The maxillary and mandibular intermolar widths decreased significantly for the extraction group (-0.74mm and -1.59mm, respectively) compared with non-extraction (1.30mm and 0.37mm, respectively). The mandibular intercanine width increased significantly for the extraction group (1.48mm) compared with non-extraction group (0.52mm). Conclusions: Orthodontic treatment with extractions of four first premolarsin Class I patients provided no significant difference in maxillary intercanine width after treatment compared to nonextraction. However, nonextraction treatment produced significantly larger values in maxillary and mandibular intermolar widths than that in the extraction group.

Progressive changes in arch width from primary to early mixed dentition period: A longitudinal study

The present study was conducted to evaluate, on a longitudinal basis, the changes in intercanine and intermolar widths form the primary to the early mixed dentition periods. A total of 38 children aged 4-5 years, with normal occlusion without any proximal caries or any dental anomalies, were selected. The impressions were recorded and casts were prepared. Intercanine and intermolar widths were measured on these dental casts with the help of a digital vernier calliper. After 3 years follow-up, the impressions were recorded again and dental casts were prepared. Intercanine and intermolar widths were measured again at this stage and were compared with the baseline data using the paired t-test and the chi square test. There is a significant increase in the intercanine (3.93 + 1.70 mm) and intermolar width (1.49 + 1.77 mm) during the transition period from primary to early mixed dentition in both the arches and both the sexes. The gender-wise comparison showed a greater increase in males than in females, but this was not statistically significant. A thorough knowledge of growth changes during various stages of the mixed dentition period are important for a pediatric dentist to make an accurate diagnosis and treatment planning during preventive and interceptive orthodontics.

Changes in mandibular transversal arch dimensions after rapid maxillary expansion procedure assessed through cone-beam computed tomography

Objective: This study aimed at evaluating the changes in mandibular arch widths and buccolingual inclinations of mandibular posterior teeth after rapid maxillary expansion (RME). Methods: Baseline and post-expansion cone-beam computed tomographic (CBCT) images of patients who initially had bilateral posterior cross-bite and underwent RME with a banded-type expander were assessed in this study. The patients included 9 boys (mean age: 13.97 ± 1.17 years) and 11 girls (mean age: 13.53 ± 2.12 years). Images obtained 6 months after retention were available for 10 of these patients. Eighteen angular and 43 linear measurements were performed for the maxilla and mandible. The measurements were performed on frontally clipped images at the following time points; before expansion (T1), after expansion (T2), and after retention (T3). Statistical significance was assessed with paired sample t-test at p ＜ 0.05. Results: T1-T2 comparisons showed statistically significant post-RME increases for all measurements; similarly, T2-T1 and T3-T1 comparisons showed statistically significant changes. The maxillary linear and angular measurements showed decreases after expansion, and mandibular linear and angular measurements increased after retention. Conclusion: All mandibular arch widths increased and mandibular posterior teeth were uprighted after RME procedure.

Arch width changes in canine and molar regions after extraction and non-extraction treatment

Arch width changes in canine and molar regions after extraction and non-extraction treatment

Dental arch widths in the early and late permanent dentitions of a Nigerian population

Objective: This study was carried out in a Nigerian population to assess arch widths at two different stages of dentition, to observe the comparative changes which may occur, and to determine the presence or absence of sexual dimorphism in arch dimensions. Material: The study population consisted of two groups of 150 subjects. Group 1 consisted of 75 males and 75 females aged 10-13 years (early permanent dentition); while Group 2 consisted of 75 males and 75 females aged 18-25 years (late permanent dentition). Measurements taken included maxillary and mandibular inter-canine, inter-premolar and inter-molar widths for both groups. Result: In the early permanent stage, the mean maxillary inter-canine, inter-premolar and inter-molar widths were 36.37mm, 45mm and 55.22mm respectively in males and 34.35mm, 42.62mm and 51.56mm respectively in females. All findings were significantly greater in males. In the mandibular arch, findings recorded in males were also significantly greater than females with the exception of the inter-canine widths. In the late permanent dentition the mean maxillary inter-canine, inter-premolar and inter-molar arch widths were 37.65mm, 46.25mm and 57.35mm respectively in males and 37.07mm, 45.21mm and 55.30mm respectively in females. Conclusion: Comparative changes in arch widths between early and late permanent dentition stages were seen with greater increases in arch widths in the maxilla when compared to the mandible. Significant sexual dimorphism was observed in almost all dimensions measured. Key words: Dental arch widths, Nigerians

Long-Term Effects of Rapid Maxillary Expansion Followed by Fixed Appliances

To evaluate the long-term changes in maxillary arch widths, overjet, and overbite in patients who were treated with rapid maxillary expansion (RME) followed by edgewise appliances. The material for the study consisted of study casts taken from 41 patients (19 males, 22 females) on four different occasions (before treatment, T1; after RME, T2; after treatment, T3; and during follow-up period, T4). The upper intercanine, interpremolar, and intermolar widths and overjet and overbite were measured on each set of study casts. Mean age of the subjects was 13.2 +/- 1.3 years (range, 11.2-16.9 years) at T1, 13.3 +/- 1.3 years (range, 11.3-17 years) at T2, 15.5 +/- 1.4 years (range, 13.1-18.8 years) at T3, and 20.4 +/- 1.6 years (range, 17.9-24.8 years) at T4. The net increase in intercanine width, interpremolar width, intermolar width, overjet, and overbite was 1.4 +/- 2.4 mm, 4.6 +/- 2.6 mm, 4.3 +/- 2.5 mm, 0.1 +/- 0.6 mm, and 0.2 +/- 0.6 mm, respectively, and the relapse rates were 37% for intercanine width, 19% for interpremolar width, and 17% for intermolar width at the end of the follow-up period. A significant amount of relapse occurred in maxillary arch widths at the postretention assessment, the greatest being in intercanine width. RME significantly decreased overbite and increased overjet, and a statistically significant decrease was observed in both overbite and overjet at the postretention assessment.

Extraction vs nonextraction: arch widths and smile esthetics.

Dental casts of 30 patients treated with extraction and 30 patients without extraction of four first premolars were randomly selected to determine changes in arch width as a result of treatment. Arch widths were measured from the cusp tips of the canines, premolars, and molars. Posttreatment arch widths were also measured in the midline at a constant arch depth from the most labial surfaces of the incisors. Standardized frontal photographs of the face taken during smiling of 12 extraction- and 12 nonextraction-treated subjects were evaluated. Fifty laypersons judged the esthetics of the smiles. Intercanine width increased less than one mm in both groups, and there was no difference between the two groups. The interpremolar and intermolar distance in both arches decreased significantly from 0.53 to 0.95 mm in the extraction sample, whereas the interpremolar and intermolar widths increased significantly from 0.81 to 2.10 mm in the nonextraction sample. When arch widths of both groups were measured from the most labial surfaces of the teeth at a constant depth, the average arch width of both arches was significantly wider in the extraction sample (1.8 mm wider in the mandible and 1.7 mm wider in the maxilla). The mean esthetic score and the number of teeth displayed during a smile did not differ between the groups. The results indicate that arch width is not decreased at a constant arch depth because of extraction treatment, and smile esthetics are the same in both groups of patients.

Differences between high- and low-angle subjects in arch form and anterior crowding from 23 to 33 years of age

The aim of this study was to compare changes in arch width and length in high- and low-angle subjects. The material comprised the cephalograms and study models of 17 males and 15 females with a high-angle and 12 males and 16 low-angle females. The age of the subjects at the first examination (T1) was 22 years 10 months and 22 years 8 months in the high-angle groups, 22 years 5 months and 22 years 8 months in the low-angle subjects, respectively, for males and females. The second assessment (T2) was 10 years and 9 years 10 months later in the high-angle and, 10 years 3 months and 9 years 10 months in the low-angle groups, respectively. Statistical analysis of changes for each group during the observation period T1-T2 was undertaken using a paired t-test, and the differences between the groups with two-sample t-tests. The findings showed a general reduction in upper and lower arch length, an increase of intermolar width, and a decrease of intercanine width in both genders. Anterior perimeter and anterior space in both angles decreased in both males and females. The mean changes were small, but with large individual differences. There were no significant differences between the genders or the high- and low-angle groups in the changes, except that the female high-angle group had a statistically significant (P = 0.05) greater decrease in mandibular arch length than the low-angle female group.

Arch width Changes with a Rapid Maxillary Expansion Appliance Anchored to the Primary Teeth

To examine the dimensional changes after rapid maxillary expansion (RME) carried out in the transitional dentition with the primary teeth as anchorage. Group A was composed of 31 consecutive transitional dentition patients with posterior quadrant crossbites treated with a Haas-type RME appliance anchored on the maxillary primary molars and canines. No treatment was administered after palatal expansion. Study models were made before RME (T1), at appliance removal (T2), and at least 1 year after appliance removal (T3). A control sample of 60 individuals with posterior quadrant crossbites who had had no orthodontic treatment was categorized into group B (30 individuals with an average age comparable with the treated patients at T2) and group C (30 individuals with an average age comparable with the treated patients at T3). Permanent molar crossbites were corrected at T2, and this correction was maintained at T3 in all patients. The mean permanent maxillary intermolar width was 42.6 +/- 2.3 mm at T1, 46.7 +/- 1.9 mm at T2 (P < .01), and 46.3 +/- 1.8 mm at T3 (P < .01) in group A; 42.9 +/- 2.7 mm (P < .01) in group B; and 44.4 +/- 3.0 (P < .01) in group C. Premolar and canine widths were slightly wider than the control at T3. To avoid undesirable treatment-induced effects on maxillary permanent molars, a stable transverse correction could be achieved with the RME appliance anchored on the primary teeth.