Morphologic changes of the palate after rapid maxillary expansion: a 3-dimensional computed tomography evaluation

3D occlusal changes of upper first molars after rapid maxillary expansion on permanent versus deciduous teeth: a retrospective multicenter CBCT study

BACKGROUND

The purpose of this study was to compare the three-dimensional dental changes for the maxillary first molars and the overall skeletal effects achieved after expansion between the rapid maxillary expansion (RME) appliance attached to two different anchor units, the maxillary deciduous molars and the maxillary permanent first molars.

METHODS

Patients were retrospectively selected according to the anchorage unit used for RME: deciduous upper second molars (RME-E group; 10 M, 10 F; mean age 8.4 ± 1.1 years) and first upper permanent molars (RME-6 group; 10 M, 10 F; mean age 12.6 ± 1.8 years). CBCT scans were obtained before treatment start (T1) and after retention and removal of the expander (T2). Images were analyzed using a new three-dimensional intra-hemi-maxillary reference system. 3D landmarks were marked to calculate all changes on maxillary first permanent molars; mesio-distal and buccal-lingual inclination and rotation, as well as intermolar and interforaminal distances were calculated. The Wilcoxon test was used to compare within-group changes, whereas the Mann-Whitney test was used to compare between-group differences, with the significance level set at 0.05.

RESULTS

In the RME-E group, significant distorotation and lingual inclination of the first permanent molars at T2 were observed (p < 0.01); in the RME-6 group, only the buccolingual inclination of the crossbite side after RME was resulted statistically significant (p < 0.01). In both groups, intermolar and interforaminal values increased significantly (p < 0.01). Intergroup analysis showed a significantly higher distorotation and reduced buccal inclination of maxillary first permanent molars in the RME-E group after RME (p < 0.01).

CONCLUSIONS

RME is effective in treating maxillary transverse hypoplasia; RME anchored too deciduous teeth spontaneously reduces buccal inclination and increases distorotation of maxillary first permanent molars, whereas anchorage to permanent molars is associated with increased buccal inclination, albeit with little clinical significance.

Evaluation of the Changes of the Intercanine and Intermolar Widths Following Palatal Expansion in the Mixed Dentition Patients with Bilateral Posterior Crossbite: A Systematic Review

This systematic review aimed to identify the intercanine and intermolar width changes following palatal expansion in bilateral posterior crossbite (PXB) in mixed dentition. This review was registered in the PROSPERO database (CRD42021275833). All randomized controlled trials (RCT) and non-RCT articles between 1980 and August 2022 on the palatal expansion of bilateral PXB in mixed dentition were searched in seven online databases (Google Scholar, Ovid, Web of Science, Scopus, EBSCOHost, Cochrane Library and PubMed). The risk of bias (RoB) of the articles included was analyzed using the Joanna Briggs Institute (JBI) critical appraisal tool. Three non-RCT studies were included and showed a low risk of bias. Meta-analysis on the changes in intercanine and intermolar widths was not performed due to study design heterogeneity. One study reported an over-correction of the bilateral PXB. There is a need for more RCT studies with standardized landmark measurements, outcome assessment methods and retention periods to investigate the interdental changes following palatal expansion.

Three-dimensional evaluation of skeletal and dental effects of treatment with maxillary skeletal expansion

INTRODUCTION

The objective was to determine the skeletal and dental changes with microimplant assisted rapid palatal expansion (MARPE) appliances in growing (GR) and nongrowing (NG) patients using cone-beam computed tomography and 3-dimensional imaging analysis.

METHODS

The sample consisted of 25 patients with transverse maxillary discrepancy treated with a maxillary skeletal expander, a type of MARPE appliance. Cone-beam computed tomography scans were taken before and after maxillary expansion; the interval was 6.0 ± 4.3 months. The sample was divided into GR and NG groups using cervical vertebral and midpalatal suture maturation. Linear and angular 3-dimensional dentoskeletal changes were assessed after cranial base superimposition. Groups were compared with independent-samples t test (P <0.05).

RESULTS

Both groups displayed marked transverse changes with a similar ratio of skeletal to dental transverse changes and parallel sutural opening from the posterior nasal spine-anterior nasal spine; a similar amount of expansion occurred in the anterior and the posterior regions of the maxilla. The maxilla expanded skeletally without rotational displacements in both groups. The small downward-forward displacements were similar in both groups, except that the GR group had a significantly greater vertical displacement of the canines (GR, 1.7 ±1.0 mm; NG, 0.6 ± 0.8 mm; P = 0.02) and anterior nasal spine (GR, 1.1 ± 0.6 mm; NG, 0.5 ± 0.5 mm; P = 0.004).

CONCLUSIONS

Treatment of patients with MARPE appliance is effective in GR and NG patients. Although greater skeletal and dental changes were observed in GR patients, a similar ratio of skeletal to dental transverse changes was observed in both groups.

Skeletal, Dental, and Soft Tissue Changes after Applying Active Skeletonized Sutural Distractor (ASSD) for Class III Malocclusion Patients

Background: Nonsurgical treatment of Class III malocclusion may reduce the chances for orthognathic surgery in the future. This study aimed to determine the post-treatment skeletal, dental and soft tissue changes in the anteroposterior plane applying active skeletonized sutural distractor (ASSD) in late adolescent Class III malocclusion patients. Materials and Methods: After screening 13,500 students from 18 secondary schools, a sample of 26 subjects was recruited for this study, with a mean age of 15(±1.4) years after considering the inclusion and exclusion criteria. ASSD appliances were inserted into patients, and lateral cephalometric x-rays were taken for pre- and post-treatment analysis. Dental casts of the patients were also taken and scanned using a 3D laser scanner for comparisons. Results: The intraclass correlation coefficients (ICC) for inter-examiner were 0.87 to 0.99 and 0.96 to 0.99 for lateral cephalometric and dental cast measurements, respectively. The difference in pre- and post-treatment of cephalometric measurements of the mandible showed statistically significant changes for mandibular plane angle (p < 0.001) and SNB angle (p = 0.029). The dental cast measurements showed statistically significant changes of inter-molars width (p < 0.001) as well as palatal (p = 0.002). Conclusions: The results showed statistically significant improvement in skeletal, dental, and soft tissue changes after treatment applying ASSD for Class III malocclusion patients.

Efficacy of the miniscrew-assisted rapid palatal expansion: An original research

Introduction:

One of the most common procedures done in orthodontics is the rapid maxillary expansion for the treatment of transverse maxillary deficiency. Hence, in the present study, we aim to evaluate the efficacy of the rapid palatal expansion assisted with the miniscrews.

Materials and Methods:

We piloted a prospective observational study among 50 age-matched adolescent participants. They were grouped equally to receive miniscrew and tooth-borne expanders. The alterations after 6 months of wearing the expanders were calculated for the root length variations of the premolars, tipping of the tooth, buccal bone thickness, and the transverse skeletal widths using the “cone-beam computed tomography” images. Comparison of the values was done between the groups using the Chi-square and ANOVA test, deliberating P < 0.05 as significant.

Results:

We observed significantly greater values for the miniscrew expander for all the four parameters than the tooth-borne device. However, there was no significant variation for the root lengths variations between the two groups. No tipping was noted for the miniscrew expander.

Conclusions:

The miniscrew palatal expander brought faster expansion of the palate than the conventional palatal expanders. The miniscrews were also safe with no adverse effects and were efficus.

Palatal changes in crossbite patients treated with rapid maxillary expansion vs untreated ones: A geometric morphometric study

OBJECTIVE

The present study aimed to analyse palatal changes due to rapid maxillary expansion (RME) by using modern geometric morphometric analysis (GMA) on 3D models.

SETTINGS AND SAMPLE POPULATION

Forty children with posterior crossbite and maxillary deficiency were selected for this study. Twenty children were treated with RME (mean age 7.4 ± 0.8 years), whereas 20 children were not treated (mean age 7.2 ± 1.1 years).

MATERIALS AND METHODS

In the treated group, RME screw was activated until overcorrection was achieved and the RME appliance remained in place for 11 months. Digital dental casts were recorded before treatment and 1 year after the end of active treatment. GMA was performed to compare shape and dimensional variations among groups (between-group principal component analysis).

RESULTS

All children in the treated group achieved crossbite correction. None of the control group children achieved crossbite self-correction. No significant shape and dimensional changes were noted in the control group after 1 year. On the other hand, significant shape and dimensional changes were noted in the treated group after 1 year (P < .05). Most of the shape changes in the treated group were similar but more pronounced compared to those observed in the control group. All major changes in palatal morphology occurred on the lateral sides of the palatal vault (widening) and at the height (shortening). Some shape changes were observed in the treated group alone.

CONCLUSIONS

Application of GMA to evaluate the effects of RME in crossbite patients revealed significant changes in palatal morphology compared with the absence of changes in the control group.

A preliminary 3-D comparison of rapid and slow maxillary expansion in children: A randomized clinical trial

BACKGROUND

This study compared the effects of rapid maxillary expansion (RME) and slow maxillary expansion (SME) using cone-beam computed tomography (CBCT).

AIM

To evaluate the skeletal and dentoalveolar effects produced by two different maxillary expansion protocols.

DESIGN

Eligibility criteria included maxillary transverse deficiencies in children (mean age, 8.18 years old), randomly assigned to either RME or SME. At the outcome analysis phase, a sample of 29 subjects were analysed (RME group, N = 16 and SME group, N = 13). CBCT scans taken before expansion and 6 months later were evaluated. Five posterior and 6 anterior transverse measurements were made at different vertical levels. Treatment changes were analysed using paired t tests; independent t tests were used to compare the two groups.

RESULTS

There were statistically significant (P<.05) increases in maxillary width at the skeletal, alveolar, and dental levels for both groups, with significantly smaller increases at the more superior than inferior levels. The RME group exhibited statistically larger width increases than the SME group for all measures except interorbital width, anterior alveolar process width, and intercanine width. The group differences were greater for anterior than posterior apical base widths.

CONCLUSIONS

Rapid maxillary expansion produced greater orthopaedic effects than slow maxillary expansion, with the greatest effects occurring in the anterior apical base.

Preliminary comparison of three-dimensional reconstructed palatal morphology in subjects with different sagittal and vertical patterns

Background

The aim of this study was to assess the difference of palatal morphology in different vertical patterns between skeletal Class I subjects and skeletal Class II subjects with retrusive mandible.

Methods

Seventy-six skeletal Class II subjects with retrusive mandible (38 females, 38 males) and 85 skeletal Class I subjects (45 females, 40 males) were collected retrospectively and divided into hyperdivergent, normodivergent and hypodivergent groups. CBCT images of these subjects were reoriented by Dolphin 3D Imaging software. Three-dimensional (3D) maxilla was segmented by ProPlan software before using Geomagic Studio software to reconstruct 3D palatal morphology. Deviation patterns on 3D colored map analysis was performed to compare the difference of 3D palatal morphology between different groups.

Results

3D colored map analysis showed that male’s palate was higher and wider than that of female in the posterior part, regardless of different sagittal and vertical patterns. In skeletal Class II subjects with retrusive mandible, males with hyperdivergent and normodivergent showed higher and narrower in the posterior part of palate, while females with hyperdivergent and normodivergent had a higher but no obviously narrow palate compared with the hypodivergent subjects. Skeletal Class II subjects with retrusive mandible showed flatter and narrower in the posterior part of palate than that of skeletal Class I subjects.

Conclusions

Sagittal and vertical patterns have great influence on the palatal morphology and as the vertical dimension increased, the palate tended to be higher and narrower.

Evaluation of palate area before and after rapid maxillary expansion, using cone-beam computed tomography

Objective:

The aim of this study was to estimate the changes in the palate area after rapid maxillary expansion (RME) with the Hyrax expander in growing subjects, using cone beam computed tomography (CBCT).

Methods:

Fourteen patients (9 girls and 5 boys; mean age = 11.7 ± 2.4 years) who required RME as part of their orthodontic treatment were included in this study. CBCT records had been taken before RME treatment (T₀), at the end of active expansion (T₁) and after a 6-month retention period (T₂). The CBCT scans were manipulated with Dolphin Imaging^® version 11.7 Premium software, in which landmarks were positioned and measured in relation to sagittal, coronal and axial planes, to verify the palate surface area. In addition, linear measurements of the palatal depth and width were assessed. These measurements were compared by using analysis of variance (ANOVA) for repeated measures. A p-value smaller than 0.05 was considered statistically significant.

Results:

The palatal surface area and width significantly increased from T₀ to T₁, respectively by 9.27% and 9.71%, and both decreased in a non-significant manner from T₁ to T₂. The palatal depth had non-significant differences at T₀, T₁ and T₂.

Conclusions:

RME promotes a significant gain in the surface area of the palate and an increase in intermolar width. The Hyrax appliance was effective for the treatment of maxillary atresia in growing patients. There was no vertical alteration of the palate. After a 6-month retention period, the maxilla transverse dimension and the surface area of the palate remained stable.

Transverse Skeletal Effects of Rapid Maxillary Expansion in Pre and Post Pubertal Subjects: A Systematic Review

OBJECTIVE

The aim of this systematic review was to assess the transverse skeletal effects of rapid maxillary expansion (RME) in pre and post-pubertal subjects.

MATERIAL AND METHODS

Five databases were searched till May 2018; Pubmed, Cochrane, Scopus, Lilacs and Web of science in addition to the manual search of other sources. There were no language restrictions. Methodological Index for Non-Randomized Studies MINORS was used to assess the quality and risk of bias of the trials included.

RESULTS

Six studies were finally included in the qualitative analysis. A meta-analysis wasn't performed due to the heterogeneity of methodologies and outcomes. All of the included studies showed drawbacks in their structure yielding weak evidence. On the short term, RME caused an increase in the maxillary and lateral-nasal widths in pre-pubertal subjects by 3.4 mm and 3.3 mm, and by 2.8 and 2.2 mm respectively in post-pubertal subjects. Although statistically insignificant, the maxillary width increase was more than that of the post-pubertal subjects by 0.6 mm. Over the long term, expansion produced permanent increases in the transverse dimensions of both the dento-alveolar and skeletal components of the maxilla and circum-maxillary structures in pre-pubertal subjects. The post-pubertal subjects presented with a statistically significant increase only in the later-nasal width by 1.3 mm than the untreated controls with no permanent increase in the skeletal maxillary width.

CONCLUSION

The literature is very deficient regarding the use of skeletal age as a reference in the treatment of skeletal crossbites using RME. Only weak evidence exists supporting the increased maxillary and lateral-nasal widths after tooth-tissue borne RME in pre-pubertal subjects, with these effects being less in the post-pubertal ones.

Morphometric covariation between palatal shape and skeletal pattern in children and adolescents: a cross-sectional study

Objective

To assess shape covariation of the palate and craniofacial complex (CFC) in children and adolescents.

Methods

Pre-treatment lateral cephalometric radiographs and corresponding maxillary casts of 100 children (8-10 years) and 100 adolescents (15-20 years) were digitized. Exclusion criteria were previous orthodontic treatment, craniofacial syndromes, mouth breathing, finger sucking, crossbite, tooth agenesis, and tooth impaction. Palatal shape was described with 239 surface and curve semilandmarks and craniofacial shape with 10 fixed landmarks and 117 curve semilandmarks. Procrustes superimposition and principal component analysis were applied for evaluation of shape variability. Shape covariation between palate and CFC was assessed with partial least squares analysis.

Results

The first five principal components explained 77 per cent (palate) and 60 per cent (CFC) of total shape variability. The palate varied mainly in height (adolescent group) and width-length (both groups), whereas the CFC varied mainly in the vertical dimension. Significant covariation was found between the craniofacial and palatal components (RV coefficient: 0.27, children; RV: 0.23, adolescents). Variation of the CFC in the vertical and anteroposterior direction was mainly related to variation in the height-width and the width-length ratio of the palate, respectively.

Limitations

The use of lateral cephalometric radiographs eliminated the transverse dimension from the craniofacial shape analysis. The study was cross-sectional, so the observed intergroup differences should be interpreted with caution.

Conclusions

Covariation strength and pattern were similar in children and adolescents. The closer a subject was to the high-angle end of the variability spectrum, the higher and narrower was the palate, and conversely.

Evaluation of miniscrew-supported rapid maxillary expansion in adolescents: A prospective randomized clinical trial

OBJECTIVES:

To evaluate and compare the dental and skeletal changes with conventional and miniscrew-supported maxillary expansion appliances in adolescents.

MATERIALS AND METHODS:

Forty patients were divided into two groups, with one group receiving a tooth-borne expander and the other group receiving an expander supported by four miniscrews (bone-borne). Multiplanar coronal and axial slices obtained from cone-beam computed tomography images were used to measure the changes in transverse skeletal widths, buccal bone thickness, tooth inclination, and root length. Paired t-tests and independent-sample t-tests were used to compare the two expansion methods.

RESULTS:

Bone-borne expansion increased the maxillary suture opening more than 2.5 times than tooth-borne expansion both anteriorly and posteriorly. Between the maxillary first premolars, sutural expansion accounted for 28% and 70% of the total transverse width increase in the tooth-borne and bone-borne expander groups, respectively. Similarly, 26% and 68% of the total expansion was of skeletal nature in the tooth-borne and bone-borne expander groups between the maxillary first molars. The pattern of expansion was variable, with most of the patients in both groups demonstrating a triangular-shaped sutural opening that was wider anteriorly. Subjects in the conventional group experienced significantly more buccal bone reduction and greater buccal inclination of the teeth. No significant differences were observed for root length measurements between the two groups.

CONCLUSION:

Use of bone-borne expansion in the adolescent population increased the extent of skeletal changes in the range of 1.5 to 2.8 times that of tooth-borne expansion and did not result in any dental side effects.

Skeletal effects of RME in the transverse and vertical dimensions of the nasal cavity in mouth-breathing growing children

Introduction:

Maxillary constriction is a dentoskeletal deformity characterized by discrepancy in maxilla/mandible relationship in the transverse plane, which may be associated with respiratory dysfunction.

Objective:

The objective of this study was to evaluate the skeletal effects of RME on maxillary and nasal transverse dimensions and compare the differences between males and females.

Methods:

Sixty-one mouth-breathers patients with skeletal maxillary constriction (35 males and 26 females, mean age 9.6 years) were included in the study. Posteroanterior (PA) radiographs were taken before expansion (T1) and 3 months after expansion (T2). Data obtained from the evaluation of T1 and T2 cephalograms were tested for normality with the Kolmogorov-Smirnov method. The Student's t-test was performed for each measurement to determine sex differences.

Results:

RME produced a significant increase in all linear measurements of maxillary and nasal transverse dimensions.

Conclusions:

No significant differences were associated regarding sex. The RME produced significant width increases in the maxilla and nasal cavity, which are important for treatment stability, improving respiratory function and craniofacial development.

Effects of Combined Bonded Maxillary Expansion and Face Mask on Dental Arch Length in Patients with Skeletal Class III Malocclusions

OBJECTIVE

To evaluate the effects of combined rapid maxillary expansion (RME) and face mask (FM) therapy during the mixed dentition period on the dental arch length in patients with skeletal Class III malocclusion.

STUDY DESIGN

We evaluated pre- and post-treatment orthodontic models of 52 patients (25 girls, 27 boys) aged 8-12 years with skeletal Class III malocclusion(ANB<0) accompanied by maxillary transverse deficiency and retrognatism treated by bonded RME-FM therapy for a mean duration of 8 months. Palatal rugae, the cusp tips of permanent first molars, deciduous molars/permanent premolars, deciduous canines and the incisal edges of permanent central incisors were marked on orthodontic models, which were then photocopied. Inter-molar, inter-premolar and inter-canine widths; the arch length; the arch depth and molar and incisor sagittal movements were measured on these photocopies. Statistical comparisons were made using paired t-tests.

RESULTS

Inter-molar, inter-premolar and inter-canine widths and the arch length showed significant increases after treatment, while the arch depth showed a significant decrease (p<0.001 for all).

CONCLUSIONS

With the study limitations, our results suggest that combined RME-FM therapy increases the arch length in the mixed dentition of patients with skeletal Class III malocclusion.

Assessment of midpalatal suture ossification using cone-beam computed tomography

BACKGROUND AND OBJECTIVE

The degree of ossification of the midpalatal suture is an important factor in the selection of treatment procedure, especially in young individuals. Considering the discrepancies in the results of studies on the exact time of the closure of this suture, the present study was undertaken to evaluate ossification and morphology of the suture with the use of CBCT.

METHODS

In the present cross-sectional study, the CBCT images of the maxilla in 144 Iranian subjects (72 males, 72 females) with an age range of 10 to 70 years, referring to a private radiology center in Sari, Iran, were evaluated. The CBCT images were evaluated in the axial cross-sectional slice at 1 mm intervals to determine morphology and the maturation stage of the suture and its degree of ossification. The six developmental stages that were observed were as follows: stage A, a direct line without disturbances; stage B, a scalloped appearance in the suture; stage C, two parallel lines with a scalloped appearance that were connected at some points; stage CD, the anterior portion was similar to stage C, and the posterior region was similar to stage D; stage D, ossification only in the palatine bone; stage E, complete ossification of the suture. The degree of ossification of the suture was calculated with the use of the ratio of the length of the ossified segment to the entire length of the suture. Data were analyzed with Spearman's correlation test, Chi-squared test, t-test, ANOVA, Mann-Whitney U, and Kruskal-Wallis test. Intra-observer agreement was calculated with the use of weighted kappa coefficient. Data were analyzed with SPSS 17.

RESULTS

There was a strong correlation between the age groups and the developmental stages of the midpalatal suture in both genders (r=0.681, p<0.001). The ossification process occurred in the posterior to anterior direction in 98% of the cases. There was a significant relationship between aging and the degree of ossification (p<0.001); however, the difference was not significant between the two genders (p=0.193).

CONCLUSION

Although the rate of suture closure increased with aging, age was not a reliable factor alone to determine the developmental stage of the suture. Use of CBCT is necessary in all the patients to determine the degree of ossification and morphology of the midpalatal suture.

Phonetic analysis during treatment with rapid maxillary expander

OBJECTIVES

To investigate possible changes and/or device-related impairments in phonetic habits produced by rapid maxillary expansion (RME).

MATERIALS AND METHODS

Thirty-five patients scheduled for RME were divided into two groups: Group A (banded two-arm Hyrax) and Group B (banded four-arm Hyrax). Speech samples were collected at six time points, before, during and after RME removal. Acoustical analysis was performed using PRAAT and BioVoice analysis tools. Ten volunteers completed a questionnaire on the acceptability of patient's speech. Maxillary dimensions and palatal volume were measured on dental casts before and after expansion using a digital gauge.

RESULTS

Voice analysis showed an increase in the peak frequency of fricative consonants (/s/,/ʃ/) after expansion, whereas there was no change of formant frequencies of palatal consonants (/ɲ/,/ʎ/). Vowel /i/ displayed a lowering of the first formant frequency, and an increase in the second and third formant frequencies. After bonding, Group B showed both a greater reduction in the peak frequency of fricatives and a greater increase in the formant frequencies of palatal consonants than Group A.

CONCLUSION

Rapid maxillary expansion causes a slight phonetic change in the acoustical parameters of both consonants and vowels. The two-arm Hyrax caused less speech impairment than the four-arm Hyrax during the treatment.

Three-dimensional analysis of palatal shape in patients treated with SARME using traditional and geometric morphometrics

OBJECTIVES

To demonstrate the advantages of dense surface models in the evaluation of surgical-assisted rapid maxillary expansion's effect (SARME) on palatal morphology. Furthermore, we compared the palatal surface before (T1) and after (T2) therapy with controls.

SETTING AND SAMPLE POPULATION

Surgical-assisted rapid maxillary expansion's effect group of 15 adult patients (Le Fort I and midpalatal sagittal osteotomy, hyrax screw) and 50 adult individuals. Patients were treated in General Faculty Hospital, Prague.

MATERIALS AND METHODS

Eighty plaster casts were digitized using a three-dimensional laser scanner and evaluated using traditional and geometric morphometrics.

RESULTS

An unpaired Student's t-test on the controls and the SARME T1 group revealed significant differences in all width measurements. Between the controls and the SARME T2 group, significant differences were only related to the interdental angle between the first molars and particularly to the palatal height. The most remarkable differences between the pre- and post-treatment palatal morphology were a widening of the dental arch and buccal shift of the lateral teeth associated with apparent flattening of the alveolar crest.

CONCLUSIONS

Dense surface model provided descriptive visualization of the treatment effect and was helpful in the evaluation of palatal shape variability including detection of the most difficult patients. Correction of the dental arch width discrepancy by SARME was successfully achieved. After therapy, palatal shape variability of most of the patients was comparable to the variability of the control group.

Rapid maxillary expansion effects: an alternative assessment method by means of cone-beam tomography

INTRODUCTION:

This study aims to develop a method to assess the changes in palatal and lingual cross-sectional areas in patients submitted to rapid maxillary expansion (RME).

METHODS:

The sample comprised 31 Class I malocclusion individuals submitted to RME and divided into two groups treated with Haas (17 patients) and Hyrax (14 patients) expanders. Cone-beam computed tomography scans were acquired at T₀ (before expansion ) and T₁ (six months after screw stabilization). Maxillary and mandibular cross-sectional areas were assessed at first permanent molars and first premolars regions and compared at T₀ and T₁. Mandibular occlusal area was also analyzed.

RESULTS:

Maxillary cross-sectional areas increased in 56.18 mm² and 44.32 mm² for the posterior and anterior regions. These values were smaller for the mandible, representing augmentation of 40.32 mm² and 39.91 mm² for posterior and anterior sections. No differences were found when comparing both expanders. Mandibular occlusal area increased 43.99mm² and mandibular incisors proclined. Increments of 1.74 mm and 1.7 mm occurred in mandibular intermolar and interpremolar distances. These same distances presented increments of 5.5 mm and 5.57 mm for the maxillary arch.

CONCLUSION:

Occlusal and cross-sectional areas increased significantly after RME. The method described seems to be reliable and precise to assess intraoral area changes.

An assessment of the maxilla after rapid maxillary expansion using cone beam computed tomography in growing children

INTRODUCTION

With the advent of cone beam computed tomography (CBCT), it is now possible to quantitatively evaluate the effects of rapid maxillary expansion (RME) on the entire maxillary complex in growing patients.

OBJECTIVE

The purpose of this study is to use three-dimensional images to evaluate the displacement that occurs at the circummaxillary sutures (frontonasal, zygomaticomaxillary, intermaxillary, midpalatal, and transpalatal sutures) following rapid maxillary expansion in growing children.

METHODS

The CBCT scans of 25 consecutively treated RME patients (10 male, 15 female) with mean age of 12.3±2.6 years, were examined before expansion and immediately following the last activation of the expansion appliance.

RESULTS

Statistically significant (P<0.05) amounts of separation were found for the displacement of the bones of the frontonasal suture, the intermaxillary suture, the zygomaticomaxillary sutures, and the midpalatal suture. The change in angulation of the maxillary first molars due to RME was also statistically significant. There was no statistically significant displacement of the transpalatal suture.

CONCLUSIONS

Rapid maxillary expansion results in significant displacement of the bones of circummaxillary sutures in growing children.

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.

Diagnostic performance of 3-dimensional evaluation of palatal vault changes in assessing successful treatment of constricted maxilla in growing subjects

INTRODUCTION

The success of maxillary expansion should not be assessed solely by the elimination of the teeth in crossbite; it should also be defined as the reestablishment of normal maxillary growth. The aim of this research was to quantify longitudinal palatal changes in children treated for maxillary constriction associated with functional crossbite.

METHODS

The subjects included 48 white children (mean age, 5.2 ± 0.6 years), divided into a treatment group (n = 23) and a control group (n = 25). Children in the treatment group had maxillary constriction associated with functional crossbite and were treated with a cemented acrylic splint expander. Dental casts were collected at baseline and at 6, 12, 18, 30, 42, and 54 months later. The casts were scanned with a laser scanner, and the palatal surface areas and volumes, and their increments over time were calculated. Nonparametric tests were used for the data analysis. The diagnostic performance in assessing successful treatment of palatal constriction was evaluated by receiver operating characteristic curves.

RESULTS

Significantly greater increments in palatal surface area and volume were seen in the treatment group up to 30 months (P <0.05, at least). According to the receiver operating characteristic curves, the best overall diagnostic performance in terms of accuracy was for palatal volume at 18 months, reaching up to a value of 0.85, by using a cutoff value of increments of 13.5%.

CONCLUSIONS

An increase in palatal volume of at least 13.5% at 18 months after treatment is a good indicator to assess the reestablishment of normal growth in subjects treated for maxillary constriction in the deciduous dentition.

Validity of palatal superimposition of 3-dimensional digital models in cases treated with rapid maxillary expansion and maxillary protraction headgear

OBJECTIVE

The purpose of this study was to evaluate the validity of the 3-dimensional (3D) superimposition method of digital models in patients who received treatment with rapid maxillary expansion (RME) and maxillary protraction headgear.

METHODS

The material consisted of pre- and post-treatment maxillary dental casts and lateral cephalograms of 30 patients, who underwent RME and maxillary protraction headgear treatment. Digital models were superimposed using the palate as a reference area. The movement of the maxillary central incisor and the first molar was measured on superimposed cephalograms and 3D digital models. To determine whether any difference existed between the 2 measuring techniques, intra-class correlation (ICC) and Bland-Altman plots were analyzed.

RESULTS

The measurements on the 3D digital models and cephalograms showed a very high correlation in the antero-posterior direction (ICC, 0.956 for central incisor and 0.941 for first molar) and a moderate correlation in the vertical direction (ICC, 0.748 for central incisor and 0.717 for first molar).

CONCLUSIONS

The 3D model superimposition method using the palate as a reference area is as clinically reliable for assessing antero-posterior tooth movement as cephalometric superimposition, even in cases treated with orthopedic appliances, such as RME and maxillary protraction headgear.

Remodelling of the palatal dome following rapid maxillary expansion (RME): laser scan-quantifications during a low growth period

OBJECTIVES

To evaluate changes in the palatal vault after rapid maxillary expansion (RME) with bonded splint appliances.

SETTING AND SAMPLE POPULATION

The sample comprised 24 children (12 boys and 12 girls) with mixed dentition (mean age 8.3 years; range 6.4-10.4 years).

MATERIALS AND METHODS

Following expansion, the splint appliance was used as a retainer for 6 months and then removed. Study casts were taken before RME (T0) and when the appliance was removed (T1). Then, 3D laser scans were taken to build complete 3D jaw models. Frontal cross sections were constructed at 53-63, 55-65 and 16-26, exported as coordinates, and finite element calculated to quantify their area, width and height. Maxillary length was also determined.

RESULTS

Paired t-tests indicated statistically significant increases in the average palatal width (T1-T0=6.53-6.79 mm) and cross-sectional area (T1-T0=20.39-21.39 mm2) after RME (p<0.001). However, small but statistically significant reductions were observed in palatal height (T1-T0=-0.49 mm, only at 55-65; p<0.001) and length (T1-T0=-0.54 mm; p<0.01). Linear regression analysis showed statistically significant (p<0.001) direct correlations between the widths and respective cross-sectional areas. Age did not influence any measurement. The reliability of the measurements was examined with an intraclass correlation coefficient (ICC). We found an ICC>0.99 (p<0.001) for all tested parameters.

CONCLUSIONS

Rapid maxillary expansion distinctly increased mean palatal widths and cross-sectional areas. However, palatal height (55-65) and maxillary length decreased to a small extent.

Nasal cavity volume changes after rapid maxillary expansion in adolescents evaluated with 3-dimensional simulation and modeling programs

INTRODUCTION

The purpose of this study was to evaluate the effects of rapid maxillary expansion on nasal cavity volume by using 3-dimensional simulation and modeling programs.

METHODS

The study group consisted of 15 patients (9 boys, 6 girls; mean age, 13.86 years) with maxillary constriction. Computed tomography scans were obtained before treatment and 6 months after the end of expansion. All computed tomography data were transferred to a computer, and the nasal cavity and maxillary teeth were segmented by using the Mimics and Simplant Ortho software programs (both, Materialise, Leuven, Belgium). Paired samples t tests were used to compare pretreatment and posttreatment nasal cavity volumes and maxillary areas. Data analysis was performed by using the software program SPSS for Windows (version 15.00; SPSS, Chicago, Ill).

RESULTS

Rapid maxillary expansion treatment induced significant increases in nasal cavity volume (P ≤ 0.001) and maxillary transverse dimensions (P ≤ 0.001).

CONCLUSIONS

Both anterior-to-posterior and coronal-to-cranial expansions were observed after rapid maxillary expansion treatment, with the direction of expansion most likely affected by resistance from the cranial bones.

Cone beam computed tomography evaluation of changes in the naso-maxillary complex associated with two types of maxillary expanders

OBJECTIVE

To test the hypothesis that there were no differences in the skeletal and dental effects of banded vs bonded expanders when evaluated using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

The experimental sample consisted of 23 patients: 13 (seven male, six female; mean age  =  12.6 ±1.8 years) and 10 (five male, five female; mean age  =  13.5 ± 2.1 years) treated with banded and bonded maxillary expanders, respectively. CBCT images were taken at T1 (pretreatment) and T2 (immediately after expansion) to evaluate the changes in the naso-maxillary complex. Relationships between and within groups were assessed using analysis of variance. If the results were significant, post hoc t-tests were used to determine where the significant differences occurred.

RESULTS

Regardless of the appliance, the maxilla was expanded equally at the level of the canines and first and second premolars. At the level of the first molars, more dental tipping and alveolar bending were evident in the banded expander group. Both appliances equally increased the skeletal and soft tissue dimensions of the nasal cavity and maxillary sinus volume. The posterior airway volume did not significantly change with either method of expansion.

CONCLUSIONS

The hypothesis was rejected. Both appliances expanded the maxilla similarly. However, in the banded group, more dental tipping and alveolar bending occurred at the level of the first molars. Maxillary expansion affected the palatal suture and demonstrated anterior and posterior skeletal widening of the nasal cavity, with corresponding soft tissue changes and increased airway volume.

Palatal volume following rapid maxillary expansion in mixed dentition

OBJECTIVE

To evaluate volumetric variations in the palate following rapid expansion, both immediately after treatment and over time.

MATERIALS AND METHODS

The sample was composed of 30 patients in early mixed dentition treated with a Haas-type device cemented onto the primary second molars. The mean age of the patients upon commencement of expansion was 7 years and 6 months (standard deviation [SD], 12 months). Measurement of palatal volume was conducted via 3D acquisition of plaster models using laser scanning before treatment (T1), upon device removal (T2), and 2.6 years afterward (T3).

RESULTS

The volume of the palate increased in a statistically significant fashion from T1 to T2 and from T1 to T3, and it decreased in a nonsignificant fashion from T2 to T3.

CONCLUSIONS

Palatal volume significantly increases with rapid maxillary expansion (RME) treatment with insignificant relapse. The use of virtual 3D models with the aid of Apposite software permits evaluation of the morphologic and volumetric changes induced by orthodontic treatment.

Dimensional changes of the nasal cavity after transpalatal distraction using bone-borne distractor: an acoustic rhinometry and computed tomography evaluation

PURPOSE

The aims of this study were as follows: 1) evaluation of the effects of transpalatal distraction (TPD) on nasal minimum cross-sectional area (MCA) and nasal volume, and assessment of long-term stability of TPD outcomes on the nasal cavity, using acoustic rhinometry (AR); 2) quantifying the alveolar, basal, and nasal components of the maxillary expansion at both canine and molar levels by computed tomography (CT); 3) investigation of the relationship between CT transverse measurements and AR measurements.

PATIENTS AND METHODS

The sample was comprised of 11 adult patients with maxillary transverse deficiency and partial/near total nasal obstruction. Standard corticotomies were carried out and bone-borne transpalatal distractors were used in all cases. AR recordings were used to determine nasal minimum cross-sectional area of the anterior (MCA1) and posterior (MCA2) and the volume of the nasal cavity in these regions (Volume1, Volume2) before surgery (T1), when the distractor was removed (T2), and at least 1 year after the expander was removed (T3). CT images were taken at T1 and T2. CT measurements included maxillary base, alveolar, and nasal cavity widths at both canine and first molar slices.

RESULTS

There were significant increases in MCAs and volumes of nasal cavity between T1 and T2 and between T1 and T3 with the exception of the right MCA2 and right Volume2 at the latter time (P < .05). All maxillary transverse dimensions in canine and molar CT slices displayed significant increases (P < .05). The change in binasal width at the canine level showed significant correlations with the changes in total MCA1 and total Volume1 (P < .05).

CONCLUSION

TPD provided great increases in MCA and volume of the nasal cavity, and these changes generally remained stable long term. The use of TPD in adult patients granted the opportunity of efficient maxillary expansion concurrent with increases in the nasal dimensions.