Functional Posterior Crossbite Research Articles

Analysis of maxillary asymmetry before and after treatment of functional posterior cross-bite: a retrospective study using 3D imaging system and deviation analysis

BackgroundPrevious evidence would suggest that subjects affected by functional posterior cross-bite (FPXB) present an asymmetric morphology of the maxilla. However, no evidence is available concerning the morphology (symmetry/asymmetry) of the maxilla after treatment of FPXB. This study aimed to investigate the volumetric and morphological changes of the palate in FPXB subjects treated with maxillary expansion and to compare these data with an untreated control group. The study sample included 20 FPXB subjects (mean age 8.1 ± 0.9 years) who underwent maxillary expansion (MEG group) and 21 FPXB subjects (mean age 7.7 ± 1.2 years) as controls (CG group). Digital models were recorded at T0 (first observation) and T1 (12–18 months after first observation) and analyzed to assess palatal volume and symmetry. Deviation analysis and percentage matching calculation were also performed between original and mirrored palatal models for each patient. All data were statistically analyzed for intra-timing, inter-timing and inter-groups assessments.ResultsAt T0, the cross-bite side (CBS) was significantly smaller than non-cross-bite side (non-CBS) in both groups (p < 0.05). At T1, the CBS/non-CBS difference reduced significantly in the MEG group (p < 0.05) while slightly worsened in the CG, however without statistical significance (p > 0.05). The matching percentage of the palatal models improved significantly at T1 in the MEG group (T0 = 74.02% ± 9.8; T1 = 89.95% ± 7.12) (p < 0.05) while no significant differences were recorded in the CG (T0 = 76.36 ± 8.64; 72.18% ± 9.65) (p > 0.05).LimitationsThe small sample size and the retrospective design of the study represent two limitations that should be overcome with further clinical trials.ConclusionsSubjects with FPXB present an asymmetric development of the maxillary vault that improves after reestablishment of normal occlusion following maxillary expansion.

Palatal changes after treatment of functional posterior cross-bite using elastodontic appliances: a 3D imaging study using deviation analysis and surface-to-surface matching technique

BackgroundThe present study aimed to evaluate the changes in palate dimension and morphology after treatment of functional posterior crossbite (FPXB) with elastodontic devices (EAs).MethodsThe treatment group (TG) consisted of 25 subjects (mean age 7.3 ± 0.9 years) who received treatment with EA for one year. The control group (CG) comprised 14 untreated subjects (mean age 6.8 ± 0.7 years). Inclusion criteria: intra-oral scan registered before (T0) and after treatment (T1), FPXB with a mandibular shift towards the crossbite site of ≥ 2 mm, class I molar relationship. Exclusion criteria: missing teeth, anterior crossbite, temporomandibular disorders, previous orthodontic treatment, carious lesions, mobility of deciduous posterior teeth, craniofacial deformities. Digital models were analyzed to assess the inter-canine (ICW) and inter-molar widths (IMW) and the corresponding emi-lateral measurements (eICW and eIMW) using the median palatine plane as reference. According to a specific 3D imaging technology, the morphology and symmetry of the palate was investigated by analysing the 3D deviation between the two specular models of the palate.ResultsAt T0, both groups showed a significantly narrower dimension of eICW and eIMW at the crossbite side compared to the non-crossbite side (p < 0.05). Also, the 3D deviation analysis demonstrates a limited matching percentage of the original/mirrored models in both TG (81.12%) and CG (79.36%), confirming the asymmetry of the palate. The area of mis-matching was located at the alveolar bone level. At T1, subjects in the TG showed a significant increment of ICW and IMW (p < 0.05), a reduction of the differences of eICW and eIMW between both sides (p < 0.05) and an increment of the percentage matching (TG = 92.32%) (p < 0.05), suggesting a significant recovery of the palatal asymmetry. No significant changes were found between T0 and T1 in the CG (p > 0.05).ConclusionsEAs could be successfully used to correct FPXB in mixed dentition and could restore the harmonious development of the palate in children.

Malocclusion in children with speech sound disorders and motor speech involvement: a cross-sectional clinical study in Swedish children

ObjectivesThe objectives of this study were to investigate the occurrence, types and severity of malocclusions in children with speech sound disorder (SSD) persisting after 6 years of age, and to compare these findings to a control group of children with typical speech development (TSD).MethodsIn total, 105 children were included: 61 with SSD and motor speech involvement (mean age 8:5 ± 2:8 years; range 6:0–16:7 years, 14 girls and 47 boys) and 44 children with TSD (mean age 8:8 ± 1:6; range 6:0–12:2 years, 19 girls and 25 boys). Extra-oral and intra-oral examinations were performed by an orthodontist. The severity of malocclusion was scored using the IOTN-DHC Index.ResultsThere were differences between the SSD and TSD groups with regard to the prevalence, type, and severity of malocclusions; 61% of the children in the SSD group had a malocclusion, as compared to 29% in the TSD group. In addition, the malocclusions in the SSD group were rated as more severe. Functional posterior crossbite and habitual lateral and/or anterior shift appeared more frequently in the SSD group. Class III malocclusion, anterior open bite and scissors bite were found only in the SSD group.ConclusionChildren with SSD and motor speech involvement are more likely to have a higher prevalence of and more severe malocclusions than children with TSD.

Articulation Therapy for Children with Speech Distortion Caused by Functional Posterior Crossbite

Articulation Therapy for Children with Speech Distortion Caused by Functional Posterior Crossbite

Condylar Changes in Children with Posterior Crossbite after Maxillary Expansion: Tridimensional Evaluation.

(1) Background: To investigate condylar position in subjects with functional posterior crossbite comparing findings before and after rapid maxillary expansion (RME) treatment through 3D analysis; (2) Methods: Thirty-two Caucasian patients (14 males, mean age 8 y 8 m ± 1 y 2 m; 18 females mean age 8 y 2 m ± 1 y 4 m) with functional posterior crossbite (FPXB) diagnosis underwent rapid palatal expansion with a Haas appliance banded on second deciduous upper molars. Patients’ underwent CBCT scans before rapid palatal expansion (T0) and after 12 months (T1). The images were processed through 3D slicer software; (3) Results: The condylar position changes between T1 and T0 among the crossbite and non-crossbite sides were not statistically significant, except for the transversal axis. At T1, the condyles moved forward (y axis) and laterally (x axis), they also moved downward (z axis) but not significantly; (4) Conclusions: Condilar position in growing patients with functional posterior crossbite did not change significantly after rapid maxillary expansion.

Intervención temprana de la mordida cruzada por la pista directa de Planas: relato de siete años de seguimiento

Introducción: entre las maloclusiones, la mordida cruzada es la de mayor prevalencia entre los niños en edad preescolar y se considera la principal depreciadora del sistema estomatognático, con un alto riesgo de desarrollar secuelas musculoesqueléticas irreparables en la edad adulta. Por lo tanto, es fundamental elegir un tratamiento eficaz que no requiera la cooperación directa del paciente y que utilice técnicas simples de ortodoncia. El objetivo de este artículo es informar la eficacia del tratamiento de rehabilitación neuroclusal (RNO) con la técnica de las pistas directas de Planas en la corrección temprana de la mordida cruzada posterior y el seguimiento de su estabilidad oclusal durante siete años. Presentación del caso: niña de 4 años de edad, que usó biberón, diagnosticada con mordida cruzada posterior funcional unilateral izquierda y desviación de la línea media. Para el tratamiento de la rno, se realizaron los ajustes oclusales en los dientes 63, 64 y 65, y después de la desprogramación neuromuscular, se confeccionaron las pistas directas de Planas en los dientes cruzados. Después de 29 días, se corrigió la mordida y se hicieron ajustes oclusales para proporcionar una mayor armonía oclusal. Hubo monitoreamiento cada seis meses durante siete años para verificar el equilibrio y la estabilidad del tratamiento. Conclusiones: a RNO con el uso de pista directa de Planas fue eficaz para corregir la mordida cruzada posterior con una técnica simple y de bajo costo que puede ejecutar el clínico general.

Correction of morphological and positional asymmetry in early mixed dentition with functional unilateral crossbite

Unilateral posterior crossbite with functional mandibular shift occurs as a sequelae of constricted maxillary arch, which is usually seen in children between 3 and 12 years of age. Early treatment of this condition helps prevent facial asymmetry, proper functioning of temporomandibular joint, masticatory muscle, and proper development of dentition. Functional unilateral posterior crossbite correction using fan-shaped expander can provide differential expansion. Fan-shaped expander was used in a patient with constricted maxilla having functional unilateral posterior crossbite with asymmetric condylar position and led to the development of favorable differential expansion and correction of asymmetry.

Three-dimensional evaluation of surgically assisted asymmetric rapid maxillary expansion.

Unilateral posterior crossbite is classified as true unilateral posterior crossbite (TUPC) or functional posterior crossbite (FPC). The differential diagnosis between TUPC and FPC is of utmost importance for the decision of expansion protocol because conventional expansion methods have some shortcomings for TUPC. The aim of this retrospective study was to 3-dimensionally evaluate the effects of asymmetric rapid maxillary expansion combined with unilateral osteotomy. This study sample comprised 16 patients (mean age 18.38±1.45) with TUPC. A Hyrax acrylic cap included the maxillary premolars and molars on the constricted side, and all teeth up to the central incisor were included on the other side to increase anchorage. Unilateral surgically assisted rapid maxillary expansion was performed and included anterior (aperture piriformis), lateral (zygomatic buttress), and posterior (pterygomaxillary junction) osteotomies on the constricted side and separation of the midpalatal suture. Cone-beam computed tomographic scans taken just before the operation and after 6months of retention were used to assess skeletal, dental, and periodontal changes. Expansion was seen on both sides; however, the amount of expansion and tipping was higher on the osteotomy+side. Because the canines were not included in the acrylic cap on the osteotomy+side, they did not present the same amount of tipping as the ipsilateral posterior teeth. More teeth were affected periodontally on the osteotomy- side; however, there were no clinically significant differences between the osteotomy+ and osteotomy- sides (mean differences range+0.54 to -0.57mm). The aperture piriformis width increased significantly on the osteotomy+side. The treatment mechanics had no clinically detrimental effects on the supporting alveolar bone of the maxilla on either side, and it was thought to be effective in cases with TUPC; however, case selection is crucial.

CBCT evaluation of condylar changes in children with unilateral posterior crossbites and a functional shift

Posterior crossbite is one of the most frequently occurring malocclusions in adolescents with a prevalence of 7% to 23%. The most common form of posterior crossbite is a unilateral posterior crossbite with a functional side shift. It has been suggested that functional posterior crossbites (FUPXB) may result in right-to-left-side differences in the condyle fossa relationship, resulting in temporomandibular joint (TMJ) problems. The objective of this study was to determine if pathological position of the condyles can cause condylar signs or symptoms like degenerative joint disease (DJD) or juvenile condylar resorption (JCR), or if the position of the condyle is just an altered position within the TMJ. Sixty patients with an average age of 9.6years were randomly selected from the office of one of the investigators (T.S.). The study group consisted of 29 patients with a FUPXB and the control group had 31 patients with no posterior crossbite. All patients had multislice CT scans of the TMJ taken as part of the orthodontic records. Transverse widths were measured at the skeletal base and the dentoalveolar base. Molar inclinations, condylar angulations, condylar anterior joint space, superior joint space, and posterior joint space were measured. Independent sample t-tests were used to compare different measurements between groups and paired sample t-tests were used to compare differences within the same patient. Reliability of measurements were determined using pairwise correlation. For dentoalveolar measurements of transverse width, the maxillomandibular difference for the study group was -8.2 mm and for the control group was -4.0 mm. No significant differences were found between the molar inclinations, condylar width, angulation, or any joint space measurements between the two groups. A total of 61.3% of the subjects in the control group and 72.4% in the study group had a radiographic sign of joint disease. The lack of condylar positional differences between the control and crossbite groups suggests that TMJ signs and symptoms in the study group may be related to remodeling in the TMJ instead.

Rapid maxillary expansion in the treatment of the functional posterior crossbite: joint noise and electromyographic activity analysis

Abstract Introduction The rapid maxillary expansion (RME) reduces the risk of developing structural and functional disorders in the stomatognathic system. Objective To examine the effects of the RME as a treatment for the posterior crossbite, related with the electromyographic activity of the masticatory muscles and the TMJ noises in a population of children. Material and method 13 girls and 7 boys, regardless of the type of malocclusion, with a mean age of 9 years old (± 3), were treated with RME. The electrovibratography analyzed the TMJ noise, and the electromyography analyzed the masticatory muscles before treatment (T0) and after three months of a short-term follow-up (T1). The comparisons of the affected and unaffected sides by the crossbite were performed using Mann-Whitney’s test, and to compare data before and after treatment the Wilcoxon’s test was used (level of significance: 5%). Result No significant differences were found in the parameters of joint noise in comparison to the sides affected and unaffected by the crossbite, in both T0 and T1 (p&gt;0.05); only the side without the crossbite observed decrease in the peak amplitude of the joint noises after treatment. In the static electromyographic analysis, inter-side differences were observed before and after treatment, since the deliberate unilateral chewing showed greater asymmetry activity in T0 for both sides, which has been corrected after treatment, improving the functional chewing. Conclusion The proposed treatment did not lead to the occurrence of joint noises and improved the functional pattern of electromyographic activity during chewing at the end of treatment.

Three-dimensional evaluation on digital casts of maxillary palatal size and morphology in patients with functional posterior crossbite.

Some authors have recently postulated the possibility of a unilateral contraction of the palate in patients with crossbite. This study aimed to investigate palatal dimension size and morphology in subjects with functional posterior crossbite and to localize location of the contraction through a 3D analysis procedure. A study sample (SS) of 35 subjects (mean age 9.2 ± 0.8 years), diagnosed with functional crossbite, and a control sample (CS) of 35 subjects (mean age 9.4 ± 0.9 years) without crossbite were selected for this study. The digital models of each patient were analysed to assess palatal dimension size and symmetry by measuring linear distances between primary canines (D1) and fist molars (D2) to the median palatine plane and by performing and analysing the 3D deviation between the two specular models of the palatal vault for each patient. Our findings demonstrate a significantly narrower dimension of D2 for the crossbite side than at the non-crossbite side. The 3D deviation analysis demonstrates a lower matching percentage of the palatal vault models in the SS (83.36%) compared with the CS (92.82%) and a location of that the palatal contraction is at the alveolar bone level. It can be assumed that there is a bilateral symmetrical contraction of the palatal vault and an asymmetric contraction of the alveolar process, but further studies are needed to corroborate this hypothesis.

Evaluation of masticatory and salivary parameters in preschool children with different morphological occlusion

Objective: To better understand the relationship between malocclusion and masticatory and salivary functions in the primary dentition, the aim was to evaluate the differences in masticatory performance (MP), facial morphology (FM), maximal bite force (BF) and salivary parameters in 65 preschool children with normal occlusion (n = 22), functional posterior crossbite (n = 20) and anterior open bite (n = 23), and to explore the relationship between these variables. Material and Methods: MP, FM and BF were assessed by sieving method, anthropometry and gnatodynamometer, respectively. Stimulated (SS) and unstimulated (US) saliva flow and composition were measured by automated colorimetric technique. Data were analyzed using ANOVA/Kruskal-Wallis, t-test/Wilcoxon and Pearson/Spearman correlation test. The relationship between SS flow rate and the independent variables were assessed using multiple linear regression. Results: The lower face dimension was smaller in crossbite-group, and a decreased BF in the crossbite-side of the dental arch was observed. BF correlated positively with intergonial width in open bite group. In malocclusion groups, better MP correlated with byzigomatic and intergonial widths. US flow rate was lower in crossbite-group and total protein concentration differed between SS and US saliva only in the crossbite-group, being lower in US. Amylase activity was higher in SS than US in all groups. SS flow rate related positively with age and negatively with the presence of malocclusion. Conclusion: In young subjects, significant correlations were found between masticatory parameters and facial dimensions; in addition, some important masticatory and salivary parameters differed between children with different morphological occlusions, hence the importance of the early assessment of these parameters.KEYWORDS Bite Force; Dental Occlusion; Masticatory System; Primary Dentition.

Asymmetric molars' mesial rotation and mesialization in unilateral functional posterior crossbite and implications for interceptive treatment in the mixed dentition.

Symmetric transverse expansion is the main outcome of the early treatment in subjects with unilateral functional posterior crossbite. The aim of this study was to analyse mesial rotation and mesialization of upper first molars as sagittal parameters to be corrected in the treatment of these patients during the mixed dentition. Digital dental cast measurements (rotation and mesialization) were performed in a sample of 48 subjects with unilateral posterior crossbite (UPXB; 19 males and 29 females, mean age 10.2 ± 1.2 years) and in a control group of 35 subjects with normal Class I occlusion (17 males and 18 females, mean age 9.9 ± 1.3 years). An independent sample t-test, the Mann-Whitney test, Fisher's exact test, and Pearson correlation were used for statistical comparison. The amount of upper molar rotation was significantly greater in the experimental group when compared with the control group. A clinically significant 'upper molar rotation' (UMR) was present in 66.7 per cent of the subjects with UPXB versus 5.7 per cent of the control group. The UMR group presented also a significant mesialization of upper first molars when compared with the control group. In the experimental group, there was a significant difference between rotation and mesialization in the right and left side and a correlation has been found between these two variables and the amount of Class II molar relationship at the crossbite side. This is an epidemiological case-control study and the discussed effects of an early correction of the asymmetric upper molars' migration are only speculations based on an association relationship. The findings of this study show an asymmetric upper first molars' migration (rotation and mesialization) in unilateral functional posterior crossbite versus a control group. An early evaluation and correction of the molars' migration during the mixed dentition should be considered in order to obtain a correct inter-occlusal sagittal molar relationship, space for an adequate eruption of permanent teeth, and perhaps reduce the need of a following fixed appliance treatment in the permanent dentition.

Functional changes after early treatment of unilateral posterior cross-bite associated with mandibular shift: a systematic review.

The objective of this systematic review was to investigate whether oral functional asymmetry in children treated for unilateral functional posterior cross-bite disappears after orthodontic treatment with a resulting normalisation of oral functions. A literature search was carried out using PubMed, Web of Science and the Cochrane Library to locate longitudinal studies reporting on clinical oral functional changes, recorded by methods including masseter muscle thickness, bite force, masticatory/chewing cycle or electromyographic masticatory muscle activity, following the treatment of unilateral functional posterior cross-bite. All potential articles were initially screened according to their title and abstract, the full text of selected articles was evaluated, and the final study selection was made based on the pre-defined criteria. Data extraction was subsequently carried out. The initial literature search identified 736 articles, with 12 articles fulfilling pre-defined criteria. Although there was a lack of high-quality prospective studies, based on the available evidence, results suggest that the abnormal masticatory cycle associated with functional posterior unilateral cross-bite tends to normalise following early cross-bite treatment. Masticatory muscle activity shows an increase after early functional unilateral posterior cross-bite treatment, and this activity approaches normal levels. Insufficient evidence was available to conclude on maximal molar bite force or masticatory muscle thickness changes following early treatment of functional unilateral posterior cross-bite. Results should be interpreted with caution due to the lack of high-quality controlled studies. Well-designed prospective studies with large patient samples and long-term follow-up are necessary before making reliable conclusions concerning change in functional asymmetry following unilateral functional posterior cross-bite correction.

Residents' journal review

Residents' journal review

Crossbite cause TMD: a good hypothesis does not make it always true

Sir, We are conscious that the review article ‘Posterior crossbite and temporomandibular disorders (TMDs): need for orthodontic treatment?’ (Thilander and Bjerklin, 2012) will find a broad readership and will contribute enormously to our understanding of orthodontic treatment need for preventive purposes. Because the assessment of the orthodontic treatment need for preventive purposes, and particularly TMDs, is complex, some additional clarification might be useful. The article contains at least two points where the reader should be warned not to draw false conclusions in the process of making a clinical decision. In their review article, the authors discussed the associations between a unilateral posterior crossbite with mandibular deviation and some signs and symptoms of TMD. They conclude that ‘Need for orthodontic treatment of a functional unilateral posterior crossbite shall first of all focus on rehabilitation of the asymmetric muscular activity and the changed condylar position in the glenoid fossae due to the mandibular displacement’. In their first paragraph, the authors state

Early Correction of Malocclusion Using Planas Direct Tracks

The correction of functional posterior crossbite through Planas Direct Tracks has many characteristics that can become advantages. The aim of this study was to present a clinical case showing how to use this procedure for early correction with resources available through public health services. The patient, a 4-year-old girl, arrived to receive treatment due to a functional unilateral crossbite. When the mandible was moved to the centric position, it was observed that the teeth had occlusal trauma. An occlusal adjustment was performed. The adjustment was not sufficient to promote functional equilibrium; thus, Planas Direct Tracks were made, resulting in functional equilibrium and correction of the malocclusion. As shown in the case report, the Planas Direct Tracks were effective for the correction of the posterior crossbite. If malocclusion is considered a public health problem, implementation of low-cost and easy-to-execute techniques is needed.

Condyle fossa relationship associated with functional posterior crossbite, before and after rapid maxillary expansion

To investigate condylar symmetry and condyle fossa relationships in subjects with functional posterior crossbite comparing findings before and after rapid maxillary expansion (RME) treatment through low-dose computed tomography (CT). Twenty-six patients (14 girls and 12 boys, mean age 9.6 ± 1.4 years) with functional posterior crossbite (FPXB) diagnosis underwent rapid palatal expansion with a Hyrax appliance. Patients' temporomandibular joints (TMJ) underwent multislice CT scans before rapid palatal expansion (T0) and after (T1). Joint spaces were compared with those of a control sample of 13 subjects (7 girls and 5 boys, mean age 11 ± 0.6 years). Anterior space (AS), superior space (SS), and posterior space (PS) joint space measurements at T0 between the FPXB side and contralateral side demonstrated no statistically significant differences. After RME treatment (T1), all three joint spaces increased on both the FPXB side and the non-crossbite side. However, differences were statistically significant only for the SS when comparing the two sides at T1. SS increased more than AS and PS in the non-crossbite condyle (0.28 mm) and FPXB condyle (0.37 mm), and PS increased only on the FPXB side (0.34 mm). There were no statistically significant differences in condyle position within the glenoid fossa between the FPXB and non-crossbite side before treatment. Increases in joint spaces were observed after treatment with RME on both sides. These changes were, however, of small amounts.

Posterior crossbite and temporomandibular disorders (TMDs): need for orthodontic treatment?

The aim of this work was to update the bibliography regarding the concept of 'temporomandibular disorder (TMD)' and 'posterior crossbite' and try to find out if there is any association between some special signs/symptoms of TMD and type of posterior crossbite. A literature search from 1970 to 2009, due to specified criterion, resulted in 14 publications that were found to be relevant for the present systematic review. An association between TMD and posterior crossbite (Yes-group) was reported as often as absence of such a relationship (No-group). The samples in the two groups showed similarities as well as differences with respect to number, gender, and age. Most articles reported only on 'presence' or 'absence' of crossbite and only few on type of crossbite opposite to a thorough account of clinical signs and symptoms of TMD. This review seems, however, to state that a functional posterior crossbite (mandibular guidance with midline deviation) is associated with headache, temporomandibular joint and muscular pain, and clicking. As evident from the discussion, such type needs orthodontic treatment to rehabilitate the asymmetric muscular activity between the crossbite and non-crossbite sides and the changed condyle/temporal relationship caused by mandibular deviation. Whether this treatment also will avoid future TMD problems can be answered only after clinical follow-up studies have been performed.

Evaluation of treatment for functional posterior crossbite of the deciduous dentition using Planas′ direct tracks

Functional posterior crossbites are a common finding in children with deciduous teeth and must be treated as soon as they are diagnosed in order to avoid unwanted changes in normal growth and development patterns. This study objective was to evaluate the changes caused by Planas' direct tracks treatment on the arch dimensions of patients with functional posterior crossbite in first dentition. The sample consisted of 20 children, 4 to 6 years old, divided into two groups, paired up according to age and gender. Group test was composed of 10 patients with functional posterior crossbite treated with PDT. Group control consisted of 10 children with normal occlusion. The evaluation criteria were intercanine and intermolar distances and Carrea's analysis (arch perimeter). All data were collected by a pre-calibrated examiner on study casts obtained at baseline and after 4 months of treatment. The statistical analysis of the data was achieved using GraphPad InStat software, version 3.05 for Windows, with the level of significance set at 0.05. For the comparison between intercanine and intermolar distances, the Tukey-Kramer Multiple Comparisons test was used. When Carrea's analysis was considered, the Mann-Whitney test was used. At the beginning of the study, all the evaluated criteria showed lower mean values in patients with posterior crossbites, and significant differences between test and control groups were noticed (P<0.05). After the end of follow-up period, these differences could not be verified (P>0.05). Within the limits of the present study, it is possible to conclude that the treatment with Planas' direct tracks was able to give back the normal dimensions of deciduous arch in patients with unilateral functional posterior crossbites, thus making it possible a better growth pattern.