Does the rhythm and appliance type of rapid maxillary expansion have an effect on root resorption?: A comparative clinical study using micro–computed tomography

ObjectivesTo evaluate the volume, amount, and localization of root resorption in the upper first premolars by micro–computed tomography (micro-CT) after three different rapid maxillary expansion appliances and two different activation rhythms.Materials and MethodsThe patients were divided into three groups; Hyrax, acrylic cap splint (ACS), and full coverage acrylic bonded (FCAB) appliances. Each group was then divided into the following two subgroups: rapid maxillary expansion (RME) and semirapid maxillary expansion (SRME). After expansion was completed, the appliances were stabilized for 12 weeks during the retention period. For each group, 10 premolars (for a total of 60 premolars) were scanned with the micro-CT (SkyScan). The reconstructed 3D images of each root sample were divided into six regions. The resorption craters on these six different root surfaces were analyzed by special CTAn (SkyScan) software for direct volumetric measurements. Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests were used for statistical analysis.ResultsThe total volume of root resorption was less with FCAB than with ACS and Hyrax (P < .001). In all groups, a greater volume of resorption was found on the buccal surface than on the lingual surface (P < .001). No significant differences were found between the RME and SRME groups (P > .05).ConclusionsAll expansion appliances caused root resorption in the upper first premolar teeth, but FCAB may be safer in terms of root resorption. The resorption craters were generally concentrated on the buccal surface. There was no effect of activation rhythm on root resorption.     

Cephalometric evaluation of rapid and slow maxillary expansion in patients with BCLP: Secondary data analysis from a randomized clinical trial

Objective:To compare the dentoskeletal effects of rapid (RME) and slow (SME) maxillary expansion in patients with bilateral complete cleft lip and palate (BCLP).Materials and Methods:This was a secondary analysis of a previous randomized controlled trial (RCT). Forty-six patients (34 male, 12 female) with BCLP and posterior crossbite (mean age of 9.2 years) were randomly assigned to two study groups. Group RME comprised subjects treated with Haas/Hyrax expander. Group SME included patients treated with quad-helix appliance. Cone-beam computed tomography (CBCT) was performed before expansion (T1) and after appliance removal at the end of a 6-month retention period (T2) for a previous RCT that compared the transverse skeletal effects of RME and SME. CBCT-derived cephalometric images were generated and cephalometric analysis was performed using Dolphin Imaging Software (Chatsworth, Calif). Intergroup comparisons were performed using t tests (P < .05).Results:Baseline forms were similar between groups. No significant differences between RME and SME groups were found.Conclusions:Rapid and slow maxillary expansion produced similar sagittal and vertical changes in patients with BCLP. Both Haas/Hyrax and quad-helix appliances can be used in patients with vertical facial pattern. Clinical relevance: RME and SME can be equally indicated in the treatment of maxillary arch constriction in patients with BCLP.     

Rapid maxillary expansion: Do banded teeth develop more external root resorption than non-banded anchorage teeth?

Objective:To compare external root resorption (ERR) when bands and wires are used as orthodontic anchorage during rapid maxillary expansion (RME).Materials and Methods:Histologic analysis was performed on 108 sites from 18 maxillary first premolars and on 36 sites from six mandibular first premolars in nine subjects (mean age = 15.2 ± 1.4 years) 3 months after RME. Maxillary teeth were pooled into two groups (n = 54 each) according to the type of orthodontic anchorage (band group [BG] vs wire group [WG]). Anchorage type was randomly chosen in a split-mouth design. Mandibular first premolars, which were not subjected to orthodontic forces, were used as the control group (CG).Results:All premolars in the BG and WG showed ERR at the level of the cementum and dentin. Repair with cementum cells was observed in all resorption areas, but complete repair was rarely found. No statistically significant difference was found between the BG and WG with regard to the ERR. No association was found between the root height position (middle or cervical third) and the incidence of ERR. Buccal root surfaces showed a higher amount of ERR compared with the palatal and interproximal surfaces. ERR was not found in any teeth in the CG.Conclusion:All maxillary first premolars subjected to RME showed ERR and partial cementum repair. Banded teeth did not develop more ERR than nonbanded anchorage teeth.     

Tooth-borne vs bone-borne rapid maxillary expanders in late adolescence

Objective:To evaluate the immediate effects of rapid maxillary expansion (RME) on the transverse skeletal and dentoalveolar changes with bone-borne (C-expander) and tooth-borne type expanders using cone-beam computed tomography (CBCT) in late adolescents.Materials and Methods:A sample of 28 female late-adolescent patients was divided into two groups according to the type of expander: bone-borne (C-expander, n  =  15, age  =  18.1 ± 4.4 years) and tooth-borne (hyrax, bands on premolars and molars, n  =  13, age  =  17.4 ± 3.4 years). CBCT scans were taken at 0.2-mm voxel size before treatment (T1) and 3 months after RME (T2). Transverse skeletal and dental expansion, alveolar inclination, tooth axis, vertical height of tooth, and buccal dehiscence were evaluated on maxillary premolars and molars. Paired t-test, independent t-test, one-way analysis of variance, and Scheffé post hoc analysis were performed.Results:The C-expander group produced greater skeletal expansion, except in the region of the first premolar (P < .05 or < .01), which showed slight buccal tipping of the alveolar bone. The Hyrax group had more buccal tipping of the alveolar bone and the tooth axes, except in the region of the second molar (P < .05 or < .01 or < .001). Dental expansion at the apex level was similar in the banded teeth (the first premolar and the first molar). Vertical height changes were apparent on the second premolar in the hyrax group (P < .05 or < .01). Significant buccal dehiscence occurred at the first premolar in the hyrax group (P < .01 or < .001). There were no significant differences between tooth types for any variables in the C-expander group.Conclusions:For patients in late adolescence, bone-borne expanders produced greater orthopedic effects and fewer dentoalveolar side effects compared to the hyrax expanders.     

Root resorption diagnosed with cone beam computed tomography after 6 months and at the end of orthodontic treatment with fixed appliances

Objective:To investigate the prevalence of orthodontically induced root resorption after treatment and the correlation with resorption found after 6 months of treatment.Materials and Methods:One hundred fifty-six patients (11–18 years) treated with fixed appliances and extraction of four premolars were examined with cone beam computed tomography before treatment, after 6 months of treatment (n  =  97), and at the end of active treatment. The Malmgren Index was used to describe the degree of root resorption.Results:Severe root resorption (>2 mm, score 3) was found in 25.6% of the patients at the end of treatment. Extreme root resorption was found in one patient. Root resorption was seen more frequently in the maxillary incisor region. There was no correlation between the severity of root resorption after 6 months and the amount observed at the end of treatment. Furthermore, no correlation was seen between treatment duration and the severity of root resorption.Conclusions:Clinically significant resorption was diagnosed in 25.6% of the patients, but no correlations, either with the resorption seen after 6 months or with the length of treatment, were found. Radiographic examination after 3 to 6 months of orthodontic treatment is too early and will not reduce the number of patients who will have teeth with severe root resorption.     

CBCT of skeletal changes following rapid maxillary expansion to increase arch-length with a development-dependent bonded or banded appliance

Objective:To assess the three-dimensional (3D) skeletal response to a standardized 5 mm of rapid maxillary expansion (RME) in growing children (6–15 years) with maxillary width deficiency and crowding.Materials and Methods:A bonded appliance was used prior to the eruption of the maxillary first premolars (Mx4s), and a banded appliance was used thereafter. A consecutive sample of 89 patients (29 boys and 60 girls) from a large pediatric dentistry and orthodontics practice was divided into four groups: 1) 6–8 years old (n  =  26), 2) 9–11 years old with unerupted Mx4s (n  =  21), 3) 9–11 years with erupted Mx4s (n  =  23), and 4) 12–15 years (n  =  19). For all patients, the 3D evaluation of dental and skeletal effects was performed with cone-beam computed tomography (CBCT).Results:For both appliances in all patients, CBCT confirmed a triangular pattern of expansion in both the frontal and sagittal planes. Overall, both appliances produced significant maxillary expansion (>80% of the 5-mm activation), but older children showed a progressively more dental (less skeletal) response. Comparison of the two types of expanders in the crossover sample, children aged 9–11 years, showed that the bonded RME produced the most efficient skeletal expansion in the preadolescent sample. Increased maxillary width at the level of the zygomaticomaxillary suture was the best indicator for development of maxillary arch circumference.Conclusion:Development-dependent appliances (bonded RPE before Mx4s erupt, and a banded device thereafter) provided optimal RME treatment for all children from age 6–15 years.     

Efficacy of injectable platelet-rich plasma in reducing alveolar bone resorption following rapid maxillary expansion: A cone-beam computed tomography assessment in a randomized split-mouth controlled trial

Objectives:To evaluate the effectiveness of platelet-rich plasma (PRP) with its growth factors in minimizing the side effects of rapid maxillary expansion (RME) on the periodontal tissue of anchoring teeth using cone-beam computed tomography (CBCT).Materials and Methods:A randomized, split-mouth clinical trial was conducted on 18 patients aged 12–16 years (14 ± 1.65) with a skeletal maxillary constriction who underwent RME using a Hyrax appliance. The sample was randomly divided into two groups: intervention and control sides. PRP was prepared and injected on the buccal aspect of supporting teeth in the intervention group. High-resolution CBCT imaging (H-CBCT) was carried out preoperatively (T0) and after 3 months of retention (T1) to study the buccal bone plate thickness (BBPT) and buccal bone crest level (BBCL) of anchoring teeth. Changes induced by expansion were evaluated using paired sample t-test (P < .05).Results:Results showed that there was no significant difference in BBPT and BBCL between the two groups after RME (P > .05). The prevalence of dehiscence and fenestrations was increased at (T1) in both groups and the percentage was higher in the PRP group.Conclusions:RME induced vertical and horizontal bone loss. PRP did not minimize alveolar defects after RME.     

Surface resorption following two forms of rapid maxillary expansion

Rapid maxillary expansion (RME) is a useful orthodontic technique for correction of posterior cross-bite of skeletal origin. The aim of the present study was to compare the frequency and nature of root resorption in premolars subjected to RME by means of either a tissue-borne, fixed split acrylic (Haas) palatal expansion applicance, or an all-wire framework appliance. Another factor examined was the relationship between the pattern of resorption and the duration of the retention period. RME was performed on five patients using the fixed split acrylic appliance and on four patients with the all-wire framework appliance. Following the transverse expansion, two upper and two lower premolars were extracted and processed for histological examination. Root resorption was found mainly on the buccal surfaces of all maxillary premolars. The resorption lacunae covered more of the root surface in premolars treated with an all-wire framework appliance compared to premolars treated with the acrylic expansion plate. The largest resorption areas were found on teeth extracted shortly after the expansion period and the smallest on premolars retained for a relatively longer period. Mandibular premolars showed neither buccal nor lingual resorptions. It was concluded that maximum anchorage of the expansion device, using the tissue-borne acrylic appliance, seems preferable in order to minimize the incidence of buccal surface root resorption. A longer post-treatment observation time is needed in order to draw more specific conclusions regarding the healing process of the damaged root surface.     

Effect of fluoride on root resorption following heavy and light orthodontic force application for 4 weeks and 12 weeks of retention

Objective:To evaluate the null hypothesis that fluoride intake via drinking water has no effect on orthodontic root resorption in humans after orthodontic force application for 4 weeks and 12 weeks of retention.Materials and Methods:Forty-eight patients who required maxillary premolar extractions as part of their orthodontic treatment were selected from two cities in Turkey. These cities had a high and low fluoride concentration in public water of ≥2 pm and ≤0.05 pm, respectively. The patients were randomly separated into four groups of 12 each: group 1HH, high fluoride (≥2 ppm) and heavy force (225 g); group 2LH, low fluoride (≤0.05 ppm) and heavy force; group 3HL, high fluoride and light force (25 g); and group 4LL, low fluoride and light force. Light or heavy buccal tipping force was applied on the upper first premolars for 28 days. At day 28, the left premolars were extracted (positive control side); the right premolars (experimental side) were extracted after 12 weeks of retention. The samples were analyzed with microcomputed tomography.Results:On the positive control side, under heavy force application, the high fluoride groups exhibited less root resorption (P  =  .015). On the experimental side, it was found that fluoride reduced the total volume of root resorption craters; however, this effect was not statistically significant (P  =  .237). Moreover, the results revealed that under heavy force application experimental teeth exhibited more root resorption than positive control groups.Conclusion:The null hypothesis could not be rejected. High fluoride intake from public water did not have a beneficial effect on the severity of root resorption after a 4-week orthodontic force application and 12 weeks of passive retention.     

Hounsfield Units: A new indicator showing maxillary resistance in rapid maxillary expansion cases?

Objective:To determine if density measurements of several maxillary regions in Hounsfield Units (HU) and outcomes of rapid maxillary expansion (RME) are correlated. Is correlation powerful enough to give us direct information about maxillary resistance to RME?Materials and Methods:Twenty-two computed tomographic (CT) scans (14 years) are used in this archive study. Two CT records were collected, one before RME (T₁) and one after 3 months of retention period (T₂). Maxillary measurements were made using dental and skeletal landmarks in first molar and first premolar slides to measure the effects of RME. Density of midpalatal suture (MPSD) and segments of maxillary bone is measured in HU at T₁. Correlation analysis was conducted between density measurements and maxillary variables. Regression analysis was then performed for variables that showed positive correlation.Results:There was no correlation between density and skeletal measurements. Intermolar angle (ImA) in molar slice showed statistically significant correlation with density measurements. The ImA variable showed the highest correlation with MPSD in frontal section (r  =  0.669, P < .01).Conclusions:There is correlation of 32.1–43.3% between density measurements and ImA increase. Our density measurements explain a certain percentage of ImA increase, but density is not the only and definitive indicator of changes after RME.     

A patient with protrusion and multiple missing teeth treated with autotransplantation and space closure

Objective:To present a patient treated with submerging autotransplantation (SA) of an immature premolar and subsequent orthodontic space closure (OSC) and to report a 10-year follow-up result.Case and Method:A 10-year-old boy had multiple missing premolars with an asymmetric pattern (maxillary right first and second premolars, teeth 14 and 15; maxillary left second premolar, tooth 25; and mandibular right second premolar, tooth 45). After considering several treatment options, tooth 35 with immature root development underwent SA into the missing site of tooth 15 at a depth 5 mm below the occlusal plane and was stabilized with sutures to create a symmetric missing condition of the premolars in the four quadrants.Results:Three months after autotransplantation, spontaneous eruption of the transplanted tooth was observed. Nine months after autotransplantation, presence of the lamina dura of the transplanted tooth was confirmed with a periapical radiograph. Active orthodontic treatment was initiated to reduce lip protrusion by closing the missing spaces of teeth 14, 25, 35, and 45 and to correct dental midline deviation. After 33 months of active orthodontic treatment, Class I canine and molar relationships were obtained. During the 10-year follow-up, the pulp vitality of the transplanted tooth was maintained without any pathologic findings, including root resorption or pulp canal obliteration.Conclusions:In a patient with lip protrusion and multiple congenitally missing premolars with an asymmetric pattern, SA of one premolar from the normal quadrant into the quadrant missing two premolars with subsequent OSC of the missing sites of the other premolars can be an effective treatment modality.     

Three-dimensional assessment of the spheno-occipital synchondrosis and clivus after tooth-borne and bone-borne rapid maxillary expansion:: A retrospective CBCT study using voxel-based superimposition

ObjectivesTo assess changes in spheno-occipital synchondrosis after rapid maxillary expansion (RME) performed with conventional tooth-borne (TB) and bone-borne (BB) appliances.Materials and MethodsThis study included 40 subjects with transverse maxillary deficiency who received TB RME or BB RME. Cone-beam computed tomography images (CBCT) were taken before treatment (T0), and after a 6-month retention period (T1). Three-dimensional surface models of the spheno-occipital synchondrosis and basilar part of the occipital bone were generated. The CBCTs taken at T0 and T1 were registered at the anterior cranial fossa via voxel-based superimposition. Quantitative evaluation of Basion displacement was performed with linear measurements and Euclidean distances. The volume of the synchndrosis was also calculated for each time point as well as the Nasion-Sella-Basion angle (N-S-Ba°). All data were statistically analyzed to perform inter-timing and intergroup comparisons.ResultsIn both groups, there was a small increment of the volume of the synchondrosis and of N-S-Ba° (P < .05). Basion showed a posterosuperior pattern of displacement. However, no significant differences (P > .05) were found between the two groups.ConclusionsAlthough TB and BB RME seemed to have some effects on the spheno-occipital synchondrosis, differences were very small and clinically negligible.     

A comparison of dentoalveolar inclination treated by two palatal expanders

The objective of the present study was to evaluate buccal dentoalveolar inclinations in subjects treated with a Hyrax (tooth-borne) or acrylic-bonded (tooth-tissue borne) palatal expander. The sample comprised 39 patients (10 males and 29 females) aged between 11 and 16 years randomly assigned to two groups. Rapid maxillary expansion (RME) was carried out with a Hyrax appliance in one group (n = 21) and with an acrylic-bonded appliance in the other (n = 18). Their mean ages were 13 years 9 months and 13 years 6 months, respectively. Orthodontic study models were obtained before RME (T1) and approximately 1 week after completion of maxillary expansion (T2). A line of barium sulphate solution was drawn between the upper first molars on the models, and radiographs were taken. The radiographic images of the models were transferred to digital medium, and buccal tipping of the molar crowns and alveolar processes were evaluated by means of a software program. The data were analysed by paired and Student's t-tests. Both RME appliances produced significant (P < 0.001) dentoalveolar tipping during RME, but this was greater in the Hyrax group (P < 0.05).     

Comparison of the effects of RME and fan-type RME on nasal airway by using acoustic rhinometry

Objective:To evaluate and compare the nasal airway changes following rapid maxillary expansion (RME) and fan-type RME using acoustic rhinometry (AR).Materials and Methods:The study sample consisted of three groups. The RME group comprised 15 subjects with maxillary transverse discrepancies and posterior crossbites. The fan-type RME group comprised 15 subjects, who had an anteriorly constricted maxilla with a normal intermolar width. The third group included 15 patients who had an ideal occlusion and received no orthodontic treatment and served as the control group. AR was used to measure nasal volume and the minimal cross-sectional area (MCA) before expansion (T1), after expansion (T2), and 6 months after expansion (T3). Each AR recording was performed with and without the use of a decongestant. Two-way analysis of variance was used to determine differences among the groups and three-way analysis of variance was used for the differences between groups. If evidence of statistically significant differences was found, a Bonferroni test was used.Results:The results showed that nasal volume and MCA were significantly increased with RME and fan-type RME immediately after expansion (P < .05). At the end of retention, nasal volume and MCA values of RME showed significant differences with both expansion fan-type RME and control groups (P < .05).Conclusions:RME and fan-type RME had similar effects on the nasal airway immediately after expansion. The increase in nasal volume and MCA was more stable in the RME group than in the fan-type RME group at the end of the retention period.     

Effects of different rapid maxillary expansion appliances on facial soft tissues using three-dimensional imaging

Objective:To determine three-dimensional (3D) effects of three different rapid maxillary expansion (RME) appliances on facial soft tissues.Materials and Methods:Forty-two children (18 boys, 24 girls) who required RME treatment were included in this study. Patients were randomly divided into three equal groups: banded RME, acrylic splint RME, and modified acrylic splint RME. For each patient, 3D images were obtained before treatment (T1) and at the end of the 3-month retention (T2) with the 3dMD system.Results:When three RME appliances were compared in terms of the effects on the facial soft tissues, there were no significant differences among them. The mouth and nasal width showed a significant increase in all groups. Although the effect of the acrylic splint RME appliances on total face height was less than that of the banded RME, there was no significant difference between the appliances. The effect of the modified acrylic splint appliance on the upper lip was significant according to the volumetric measurements (P < .01).Conclusions:There were no significant differences among three RME appliances on the facial soft tissues. The modified acrylic splint RME produced a more protrusive effect on the upper lip.     

Comparison of root resorption between self-ligating and conventional preadjusted brackets using cone beam computed tomography

Objective:To compare the magnitude of external apical root resorption (EARR) of incisors in patients undergoing the initial phase of orthodontic treatment with two sets of brackets.Materials and Methods:According to the results of the power analysis for sample size calculation, 19 Angle Class I patients (anterior crowding: 3 to 5 mm; mean age: 20.6 years) were included in the study and randomly divided into two groups: group I (n  =  11, self-ligating brackets) and group II (n  =  8, conventional preadjusted brackets). The degree of EARR was detected in 152 upper and lower incisors by using cone-beam computed tomography (CBCT) scans and a three-dimensional program (Dolphin 11.5, Dolphin Imaging & Management Solutions, Chatsworth, Calif) with 25% level of sensitivity. The CBCT scans were obtained before (T1) and 6 months after initiation of treatment (T2). Differences between and within groups were analyzed by nonpaired and paired t-test, respectively, with 5% significance level.Results:Significant differences were found for both groups between T1 and T2. However, no differences in the degree of EARR were detected between the groups studied.Conclusions:Although EARR has occurred in all teeth evaluated, the bracket design (self-ligating or conventional) did not demonstrate any influence on the results observed.     

Symmetry of root anatomy and root canal morphology in maxillary premolars analyzed using cone-beam computed tomography

ObjectiveThis study aimed to use cone-beam computed tomography (CBCT) to evaluate the root anatomy and canal morphology of maxillary premolars in a Chinese population and determine their degree of bilateral symmetry.Design774 CBCT images were retrospectively analyzed, representing 1387 maxillary first premolars and 1403 second premolars. The number of roots and canals were recorded. The morphology of root canal systems was determined according to Vertucci’s classification. The symmetry of root and canal anatomies between maxillary contralateral premolars was further evaluated.ResultsThe most common anatomy of maxillary first and second premolars was one-rooted with two canals (58.0%) and one-rooted with one canal (50.3%), respectively. The typical canal morphology was type IV (42.7%) in maxillary first premolars and type I (50.3%) in maxillary second premolars. One-rooted maxillary premolars exhibited a higher variability in the canal morphology, compared to two-rooted or three-rooted teeth. Maxillary second premolars exhibited greater anatomic symmetry than first premolars. The root and canal numbers showed bilateral symmetry between 80.2% of maxillary first premolar pairs and 81.8% of second premolar pairs. Bilateral symmetry in both number and morphology of roots and canals was observed for 72.3% of maxillary first premolar pairs and 73.2% of second premolar pairs.ConclusionThe root anatomy and canal morphology of maxillary premolars in a Chinese population were quite diversified. Maxillary contralateral premolars demonstrated a high degree of symmetry in root and canal anatomies, which enables practitioners to better determine the nature of the root canal system during treatment of opposite homonymous teeth.     

Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man

This study was designed to investigate human repair and reattachment of principal periodontal fibers in areas of resorption on anchor premolar root surfaces following rapid maxillary expansion. Maxillary first premolar teeth were obtained from patients requiring rapid maxillary expansion. Extraction of the teeth was scheduled after periods of retention varying between 14 and 53 weeks. The roots of the teeth were examined via light microscopy and scanning electron microscopy. Extensive root resorption characterized the buccal surfaces of anchor premolars. Repair of the resorptive defects was found to occur exclusively with cellular cementum. Anchor teeth retained for longer periods, up to the maximum of 53 weeks of retention in this study, generally demonstrated more advanced repair. Topographically, Sharpey fiber holes indicative of principal periodontal fiber insertion were found in repair cementum. However, these depressions were neither numerous nor consistent in their presence and location. In human teeth, periodontal attachment to resorbed and repairing surfaces was shown to be present. SEM studies of histologic sections revealed that periodontal fibers and fiber bundles inserted directly into the repair cellular cementum matrix, irrespective of the site of the lesion on the root.     

Root resorption extremes resulting from clinical RME

An assessment has been made of the area of root surface resorption on extracted RME anchor premolar teeth from eighteen patients held in fixed retention for periods varying between 14 and 52 weeks. The areas of resorption present were extensive but did not increase significantly over the time interval studied. By comparison, the proportion of repair tissue in the defects became greater with the more prolonged retention periods. The topographic findings suggest that strong relapse forces are probably dissipated after 3 months of retention. This investigation showed no correlation between the period of RME, the length of retention, and the total area of resorption affecting the anchor teeth. These findings are discussed in relation to retention following RME.     

Effects of symmetric and asymmetric rapid maxillary expansion treatments on pharyngeal airway and sinus volume:: A cone-beam computed tomography study

ObjectiveTo evaluate pharyngeal airway and maxillary sinus volumes following symmetric rapid maxillary expansion (RME) and asymmetric rapid maxillary expansion (ARME) treatment using cone-beam computed tomography (CBCT).Materials and MethodsThe study consisted of 60 patients presenting to the orthodontics clinic with an indication that they required symmetric or asymmetric rapid maxillary expansion treatment. Individuals were included if they were aged 12–15 years and had symmetric (RME group; 14 girls, 16 boys) or asymmetric (ARME group; 16 girls, 14 boys) maxillary deficiency. Maxillary sinus volume (mm³) and pharyngeal airway volume (upper, lower, and total; mm³) were evaluated using CBCT records. The parameters were compared before treatment (T1) and after 3 months in retention (T2).ResultsAll measurements at T2 were increased significantly compared with T1 in the RME group (P < .05). In the ARME group, changes in the lower pharyngeal airway and the nonaffected maxillary sinus volumes (non-affected side of maxillary sinus volumes) were not significant; however, the other measurements increased significantly from T1 to T2 (P < .05). Intergroup comparisons revealed that total pharyngeal airway volume and total maxillary sinus volume changes were significantly greater in the RME group.ConclusionsPharyngeal airway and maxillary sinus volumes increased with both RME and ARME treatment. Both were found to be effective for treating transverse maxillary deficiency.