Tooth-borne Expander Research Articles

Efficacy of the rapid maxillary expansion with a modified acrylic splint palatal expander: A randomized clinical trial

Aim: This prospective randomized clinical trial aimed at analyzing the skeletal effects of this modified acrylic splint palatal expander (MASPE) used for maxillary transversal deficiency treatment in mixed dentition. Methods: Eligibility criteria included maxillary transverse deficiencies in children between 7 and 10 years of age. Eighteen individuals who met the inclusion criteria and reached the end of treatment were evaluated (mean age of 8.66 years old) and randomly assigned to be submitted to rapid maxillary expansion with either the MASPE experimental device or a well-known tooth-borne expander (control group). CBCT scans taken before expansion and at the end of the retention period were evaluated. The palatal area was calculated, and the length of expansion was measured. Treatment changes were analyzed using paired t-tests, whereas independent t-tests were used to compare the two groups. Results: There were statistically significant (p<0.05) increases in maxillary width at the suture level in both groups, with a substantial increase in the palatal area. The group differences were not significant. Conclusions: MASPE showed good efficiency and skeletal effects but no superiority over the control group. Keywords: Maxillary expansion; Mixed Dentition; Orthodontics; Orthopedics

Torque changes of anchorage units in preadolescent patients treated with a digitally designed tooth-borne expander anchored to deciduous vs. permanent molars.

To compare the effects on permanent or deciduous anchorage dental units in patients treated with a digitally designed palatal expander. Inclusion criteria were the following: presence of maxillary transverse deficiency, no previous orthodontic treatment, no extractions, absence of agenesis, congenital pathologies and cranio-maxillofacial malformations. Twenty patients (11 males, 9 females, 11 ± 1.8 years) received a digitally designed and metal printed palatal expander anchored on first permanent molars and 1 activation per day for 30 days (Group 1). Twenty-one patients (12 males, 9 females, 8.6 ± 1.4 years) received a digitally designed and metal printed palatal expander anchored on second deciduous molars and 2 activations per day for 14 days (Group 2). Digital intraoral scans were taken before expansion and after device removal, and torque and the palatal transverse diameter were digitally measured. The FDI notation was used to indicate each tooth CONCLUSION: Less dental torque augmentation was produced in Group 2. Significant intragroup differences over time were found in Group 1 considering the torque of teeth 1.6, 1.4, 1.3, 2.1, 2.4, 2.5, 2.6. Significant differences between groups were found regarding the longitudinal change in torque of teeth 1.5, 2.4 and 2.5. Significant intragroup differences over time were found in both groups considering all transverse diameter parameters. No significant differences were found between groups in the transverse diameter modifications over time. Less dental torque augmentation was produced in Group 2.

Dento-skeletal effects of different rapid maxillary expanders for growing patients-which is better?

Single-blind, two-arm parallel-group randomised controlled trial. Patients aged 11-14 years old attending for comprehensive orthodontic treatment between January and July 2018. All subjects needed to have the following: present upper first premolars and first permanent molars; transverse maxillary deficiency; unilateral or bilateral posterior crossbite. The exclusion criteria was: cleft lip or palate, previous orthodontic treatment; congenital deformity; absent permanent teeth. Rapid maxillary expansion via two techniques were used and placed by the same orthodontist. Group A were treated via the tooth-bone-borne Hybrid Hyrax expander, Group B had the tooth-borne (hyrax) expander. CBCT scans of the maxilla were taken before treatment and 3 months after the activation phase when the appliances had been removed. Analysis of the dental and skeletal changes was completed via measuring pre and post treatment CBCT scans using Dolphin software for Group A and Group B. Measurements included: specific naso-maxillary widths in the first premolar region (i.e. nasal cavity, nasal floor, maxilla, palate), naso-maxillary widths in the first molar region, premolar/molar inclination, buccal cusp distance, and apices distance, as well as suture maturation. Baseline characteristic data was compared using one-way ANOVA. Intergroup comparison of changes was analysed using ANCOVA. P < 0.05 (5%) was considered statistically significant. Inter-rater reliability was assessed using correlation coefficient. Skeletal effects: The Hybrid Hyrax patients (HHG) showed a significantly higher increase in dimensions in the nasal cavity, nasal floor and maxilla in the premolar region only, of 1.5 mm, 1.4 mm and 1.1 mm, respectively, compared to the Hyrax expander patients (HG), to a 5% significance level. The HHG showed a significantly higher increase in dimensions in the nasal cavity of 0.9 mm, in the molar region, compared to the HG. Dental effects: Premolar inclination was significantly higher in the HG, with the difference being -3.2 degrees on the right 1st premolar and -2.5 degrees on the left 1st premolar. The higher the amount of activation, the higher the nasal skeletal changes in the Hybrid Hyrax group. The Hybrid Hyrax (tooth-bone-borne expander) resulted in increased skeletal dimension changes (i.e. in the nasomaxillary structures in the first premolar region, and nasal cavity in the first molar and first premolar region) and only minimal premolar inclination/tipping compared to the Hyrax (tooth-borne expander). There were however no differences between the expanders for position of premolar or molar apices, or molar crowns.

Comparison of the effects of different rapid maxillary expansion techniques on craniofacial structures: a finite element analysis study

AimTo compare the effects of three different maxillary expansion appliances with five different types of expansion modalities on stress distribution and displacement on the maxilla and its adjacent craniofacial structures using the finite element method (FEM).Materials and methodsCone-beam computed tomography data of a patient with maxillary transverse deficiency were rendered into a three-dimensional model of craniomaxillary structures. The expansion appliances included tooth-borne, hybrid, and bone-borne expanders. Five different expansion modalities were applied to each expander [conventional Rapid Maxillary Expansion (RME) (type 1), midpalatal suture cortico-puncture-assisted RME (type 2), LeFort l cortico-puncture-assisted RME (type 3), surgically assisted RME (SARME) without pterygomaxillary junction (PMJ) separation (type 4), and SARME with bilateral PMJ separation (type 5)]. The numerical and visual data were analyzed.ResultsThe highest amount of stress accumulation on teeth was found in the tooth-borne and hybrid groups. On the other hand, more stress concentration on the maxilla was observed in the bone-borne group. SARME cuts with PMJ separation increased total movement by reducing the stress on the midpalatal suture in all groups. While types 1, 2, and 3 were similar in terms of the amounts of displacement, types 4 and 5 increased the total amount of displacement in all groups. The total amounts of displacements from the highest value to the lowest value for the anterior and posterior maxilla were in the bone-borne, tooth-borne, and hybrid groups.ConclusionsSARME cuts were effective in reducing stress on the teeth, but the cortico-puncture application affected neither the stress values on the teeth nor the transverse displacement in the tooth-borne expanders. Surgical procedures such as SARME and corticotomy should be used with bone-borne devices to improve the outcomes of maxillary expansion procedures.

THE EFFICIENCY OF TOOTH-ANCHORED VERSUS BONEANCHORED RAPID MAXILLARY EXPANSION IN YOUNG AND LATE ADOLESCENT PATIENTS

Relevance of the problem. Incidence of posterior cross­bite has been reported to be 8–23% and it is a com­mon problem often seen in children and adolescents. An effective treatment of the skeletal transversal maxillary deficiency usually involves rapid maxillary expansion (RME). The expansion can be achieved using different types of expanders: bone anchored, tooth anchored or hybrid. The variety of clinical results comparing bone-borne and tooth-borne RME influence lack of unanimous treatment plan for adolescents. Aim. To compare the efficiency of tooth-borne expanders with bone-borne expanders by comparing dentoskeletal changes evaluated by CBCT. Material and methods. Electronic database search was carried out according to PRISMA principles. Five electro­nic research databases were searched including Medline (via PubMed), Cochrane Library, ProQuest, Wiley On­line Library and Web of Science. PICOS framework was used to form a focused question and the risk of bias was assessed using the Cochrane tool for randomized trials (RoB 2) by two individual researchers. Included studies were randomized clinical trials, published less than 10 years ago, with minimum follow-up period of 9 months with CBCT. Results. Two studies proved that bone borne RME produ­ced greater results in skeletal expansion, however other two studies failed to confirm these findings. Regarding alveolar bone loss, the results were also contradictory: two studies found no significant difference in both RME groups, however, other two studies found that bone borne RME exhibit less alveolar bone loss. As for den­tal tipping, the results were also different in all studies: In a study performed by Lagravere et al (2013), dental tipping occurred regardless of RME treatment for molar teeth, however in the premolar group, increased tipping was noticed in the tooth-anchored group. Another study by the same author concluded similar results: in the to­oth borne RME group no significant tipping in molars was seen, while in premolars, buccal crown tipping was observed, which was significant (p&lt;0.003). In the bone borne RME group significant dental tipping was obser­ved in molars. Contrary to these findings, two studies concluded that dental tipping is experienced significantly less in the bone-borne RME group and one study per­formed by Davami et al found no significant difference in both groups. Conclusion. To conclude, current evidence suggests contradictory results in maxillary expansion using bone borne or tooth borne RME devices. Though the evidence is limited, both types of RME have similar outcomes. More studies with a higher number of patients are nee­ded to determine conclusive results.

Differences in dentoskeletal and soft tissue changes due to rapid maxillary expansion using a tooth-borne expander between adolescents and adults: A retrospective observational study.

ObjectiveThe purpose of this study was to compare the differences in dentoskeletal and soft tissue changes following conventional tooth-borne rapid maxillary expansion (RME) between adolescents and adults.MethodsDentoskeletal and soft tissue variables of 17 adolescents and 17 adults were analyzed on posteroanterior and lateral cephalograms and frontal photographs at pretreatment (T1) and after conventional RME using tooth-borne expanders (T2). Changes in variables within each group between T1 and T2 were analyzed using Wilcoxon signed-rank test. Mann–Whitney U test was used to determine the differences in the pretreatment age, expansion and post-expansion durations, and dentoskeletal and soft tissue changes after RME between the groups. Spearman’s correlation between pretreatment age and transverse dentoskeletal changes in the adolescent group was calculated.ResultsDespite similar amounts of expansion at the crown level in both groups, the adult group underwent less skeletal expansion with less intermolar root expansion after RME than the adolescent group. The skeletal vertical dimension increased significantly in both groups without significant intergroup difference. The anteroposterior position of the maxilla was maintained in both groups, while a greater backward displacement of the mandible was evident in the adult group than that in the adolescent group after RME. The soft tissue alar width increased in both groups without a significant intergroup difference. In the adolescent group, pretreatment age was not significantly correlated with transverse dentoskeletal changes.ConclusionsConventional RME may induce similar soft tissue changes but different dentoskeletal changes between adolescents and adults.

Comparison of changes in skeletal, dentoalveolar, periodontal, and nasal structures after tooth-borne or bone-borne rapid maxillary expansion: A parallel cohort study

This parallel cohort study aimed to assess the dentoalveolar, skeletal, periodontal, and airway effects of tooth-borne (hyrax) and computer-guided miniscrew-supported rapid palatal expansion appliances. Thirty-six subjects were randomly allocated into 2 groups. Eighteen subjects (mean age, 12.2 years; male-to-female ratio, 10:8) were assigned to receive treatment with the hyrax appliance (group A), and 18 subjects were treated with the computer-guided miniscrew-supported appliance (group B). The same type of expansion screw and expansion protocol was used in both groups. Linear and angular measurements of skeletal, dentoalveolar, periodontal, and nasal floor changes were performed on the pretreatment and posttreatment cone-beam computed tomography images (6-month follow-up). Descriptive statistics and the independent Student t test were used for the statistical analysis. Intraoperator reliability was evaluated using a 2 sample t test. The level of significance was P≤0.05. Ten subjects were censured because posttreatment cone-beam computed tomography imaging was not performed because of the coronavirus disease 2019 pandemic. In the remaining 26 subjects, increases in linear measurements were observed in both groups. The transversal skeletal increase was greater and statistically significant in the group treated with the bone-borne expander (P≤0.05). The dentoalveolar transverse diameters were greater in the tooth-supported expander group, with no statistically significant difference between the groups. The buccal inclination of the maxillary first molar was observed in the group with the tooth-borne expander, with a statistically significant difference between the 2 groups. A slight reduction of buccal and palatal thicknesses at the level of the maxillary first molars was observed in both groups, smaller in the skeletal expander group, with a statistically significant difference between the 2 groups only on the right buccal cortical plate. The width of the nasal floor increased more in the group with skeletal expander with a statistically significant difference of 2 mm. Computer-guided miniscrew-supported maxillary expanders allowed a greater transversal increase of the nasal-maxillary skeletal structures by reducing the dentoalveolar side effects of the tooth-supported devices.

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.

Skeletal, dentoalveolar, and buccal bone changes using hybrid and tooth-borne expanders for RME and SARME in different growth stages

Abstract Objective To compare the skeletal, dentoalveolar and buccal bone thickness of tooth–bone-borne (Hybrid-H) and tooth-borne (TB) maxillary expanders used for rapid maxillary expansion (RME) in early and late adolescents and for surgically-assisted RME (SARME) in young adults. Materials and methods: This two-centre clinical study included initial and 6 months post-retention CBCT records of 60 patients (27 males, 33 females; mean age 15.7 ± 3.75 years). The cohort was divided into two groups according to the expander type (H or TB) and subdivided into a further three groups determined by cervical vertebrae maturation stages: early adolescents (EA), late adolescents (LA), and young adults (A). EA and LA patients underwent RME and young adults received a SARME. Results: The hybrid-designed appliance increased the internal skeletal maxillary width and nasal width more than the TB-designed appliance anteriorly in EA and posteriorly in SARME young adults. The TB expanders tipped and expanded the first premolars more than the Hybrid SARME expanders in young adults and caused a greater reduction in buccal alveolar bone thickness at the level of the first premolars and molars at the three growth stages. Conclusion The hybrid expanders, with relatively greater skeletal and nasal widening potential and fewer dentoalveolar side effects, were a favourable alternative to tooth-borne expanders for RME in the early and late adolescents, and for SARME in young adults.

Fibre Bragg grating sensors for sutural expansion assessment in rapid palatal expanders: an ex‐vivo validation

This study presents the development and validation of a fibre Bragg gratings (FBGs)-based sensor system for the assessment of strain in the midpalatal suture in subjects using rapid palatal expanders (RPEs). The ex-vivo experiments were made by means of positioning two RPEs in a porcine palatal region. The RPEs used were the Hyrax, a tooth-borne expander and MARPE (microimplant-assisted rapid palatal expansion), a bone-borne expander. In order to define the regions in the palatal region for the sensors positioning, a finite-element analysis was performed in a porcine head subjected to the loadings caused by an RPE. In addition, a strain transfer model was used to obtain a correction coefficient that approximates the strain estimated by the FBG to the actual strain in the structure under shear and normal stress. Results show high linearity in the sensors characterisation tests with the advantages of compactness, intrinsic safe operation and multiplexing capabilities of FBGs. In the RPE analysis, a higher strain was estimated in the anterior region, which is in accordance with the simulation and previously reported results, where MARPE showed a higher strain (with an exponential pattern) than Hyrax as the number of activations increase.

Evaluation of the changes of orbital cavity volume and shape after tooth-borne and bone-borne rapid maxillary expansion (RME)

ObjectiveTo assess and compare volumetric and shape changes of the orbital cavity in patients treated with tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME).Study designForty adolescents with bilateral maxillary cross-bite received tooth-borne (TB group = 20; mean age 14.27 ± 1.36 years) or bone-borne (BB group = 20; mean age of 14.62 ± 1.45 years) maxillary expander. Cone-beam computed tomography (CBCT) were taken before treatment (T1) and 6-month after the expander activation (T2). Volumetric and shape changes of orbital cavities were detected by referring to a specific 3D digital technology involving deviation analysis of T1/T2 CBCT-derived models of pulp chamber. Student’s t tests were used to 1) compare T1 and T2 volumes of orbital cavities in TB and BB groups, 2) compare volumetric changes and the percentage of matching of 3D orbital models (T1-T2) between the two groups.ResultsBoth TB and BB groups showed a slight increase of the orbital volume (0.64 cm3 and 0.77 cm3) (p < 0.0001). This increment were significant between the two groups (p < 0.05) while no differences were found in the percentage of matching of T1/T2 orbital 3D models (p > 0.05). The areas of greater changes were detected in the proximity of the frontozygomatic and frontomaxillary sutures.ConclusionTB-RME and BB-RME would not seem to considerably affect the anatomy or the volume of the orbital cavity in adolescents.

A comparison of tooth-borne and bone-anchored expansion devices in SARME.

Major adult maxillary transverse discrepancies are usually treated with surgically assisted rapid maxillary expansion (SARME), utilizing a combination of surgical and orthodontic techniques. Unfortunately, a consensus has not been reached on topics ranging from the best surgical technique that should be performed to the ideal expander type that should be installed. The present study sought to evaluate the efficiency and stability of the maxillary expansion achieved with two types of expanders following the same SARME procedure without pterygomaxillary disjunction (PMD). Twenty-four patients with a maxillary transverse deficiency were enrolled in the study. All patients underwent the same SARME, and 12 received a bone-anchored (KLS Martin®) and 12 were installed with a tooth-borne (Hyrax®) expander. Dental impressions were collected both preoperatively and 1year postoperatively. These casts were scanned and the distances between specific interdental and intergingival points were measured and analyzed. Statistical analyses were performed to assess the effects expander type had on the efficiency of the maxillary expansion and long-term stability. Expansion in the anterior maxillary and premolar regions was found to be similar in both groups. In contrast, the tooth-borne device resulted in a significantly greater expansion in the molar region. The SARME technique without PMD is highly effective at treating adults with maxillary transverse deficiencies, and the type of expander selected depends on the location of the larger maxillary constriction region of each patient.

Buccal alveolar bone thickness changes after rapid maxillary expansion with tooth-borne and bone-borne expanders

Buccal alveolar bone thickness changes after rapid maxillary expansion with tooth-borne and bone-borne expanders

Retrospective CBCT analysis of airway volume changes after bone-borne vs tooth-borne rapid maxillary expansion.

To compare changes in upper airway volume after maxillary expansion with bone- and tooth-borne appliances in adolescents and to evaluate the dentoskeletal effects of each expansion modality. This retrospective study included 36 adolescents who had bilateral maxillary crossbite and received bone-borne maxillary expansion (average age: 14.7 years) or tooth-borne maxillary expansion (average age: 14.4 years). Subjects had two cone beam computed tomography images acquired, one before expansion (T1) and a second after a 3-month retention period (T2). Images were oriented, and three-dimensional airway volume and dentoskeletal expansion were measured. Analysis of variance was used to test for differences between the two expansion methods for pretreatment, posttreatment, and prepost changes. Paired t-tests were used to test for significance of prepost changes within each method. Both groups showed significant increase only in nasal cavity and nasopharynx volume (P < .05), but not oropharynx and maxillary sinus volumes. Intermolar and maxillary width increased significantly in both groups (P < .05); however, the buccal inclination of maxillary molars increased significantly only in the tooth-borne group (P < .05). There was no significant difference between tooth- and bone-borne expansion groups, except for the significantly larger increase in buccal inclination of the maxillary right first molar after tooth-borne expansion. In adolescents, both tooth- and bone-borne RME resulted in an increase in nasal cavity and nasopharynx volume, as well as expansion in maxillary intermolar and skeletal widths. However, only tooth-borne expanders caused significant buccal tipping of maxillary molars.

Zygomaticomaxillary modifications in the horizontal plane induced by micro-implant-supported skeletal expander, analyzed with CBCT images

BackgroundMiniscrew-assisted rapid palatal expansion (MARPE) has been adopted in recent years to expand the maxilla in late adolescence and adult patients. Maxillary Skeletal Expander (MSE) is a device that exploits the principles of skeletal anchorage to transmit the expansion force directly to the maxillary bony structures and is characterized by the miniscrews’ engagement of the palatal and nasal cortical bone layers. In the literature, it has been reported that the zygomatic buttress is a major constraint that hampers the lateral movement of maxilla, since maxilla is located medially to the zygomatic arches. The objective of the present study is to analyze the changes in the zygomatic bone, maxillary bone, and zygomatic arches and to localize the center of rotation for the zygomaticomaxillary complex in the horizontal plane after treatment with MSE, using high-resolution cone-beam computed tomography (CBCT) images.MethodsFifteen subjects with a mean age of 17.2 (± 4.2) years were treated with MSE. CBCT records were taken before and after miniscrew-assisted maxillary expansion; three linear and four angular parameters were identified in the axial zygomatic section (AZS) and were compared from pre-treatment to post-treatment using the Wilcoxon signed rank test.ResultsAnterior inter-maxillary distance increased by 2.8 mm, posterior inter-zygomatic distance by 2.4 mm, angle of the zygomatic process of the temporal bone by 1.7° and 2.1° (right and left side) (P < 0.01). Changes in posterior inter-temporal distance and zygomaticotemporal angle were negligible (P > 0.05).ConclusionsIn the horizontal plane, the maxillary and zygomatic bones and the whole zygomatic arch were significantly displaced in a lateral direction after treatment with MSE. The center of rotation for the zygomaticomaxillary complex was located near the proximal portion of the zygomatic process of the temporal bone, more posteriorly and more laterally than what has been reported in the literature for tooth-borne expanders. Bone bending takes place in the zygomatic process of the temporal bone during miniscrew-supported maxillary expansion.

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

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

Displacement and stress distribution by different bone-borne palatal expanders with facemask: A 3-dimensional finite element analysis.

The purpose of this study was to analyze displacement and stress distribution in the maxilla during maxillary expansion followed by protraction using bone-borne and conventional tooth-borne palatal expanders and a facemask via 3-dimensional finite element analysis. A finite element model of an adolescent skull was created, and 4 different types of appliances were integrated into it: facemask (type A); facemask with paramedian bone-borne expander (type B), facemask with palatal-slope bone-borne expander (type C), and facemask with conventional expander (type D). Expansion of 0.25mm followed by 500g of force per side was applied. Type A showed anterior displacement of the dentition combined with downward displacement of posterior teeth and upward displacement of anterior teeth. The combination of protraction and expansion in type D showed the greatest anterior displacement. In types B and C, the expansion forces resulted in posterior displacement decreasing the net displacement of the combination. Stresses concentrated around the miniscrews in types B and C. In types A and D, stresses concentrated at the first premolar and first molar. Type B had the highest stresses followed by type C and then D. The conventional tooth-borne expander (type D) enhanced the effect of maxillary protraction. Facemask alone (type A) resulted in more anterior displacement of the maxilla than the combination of facemask and bone-borne expanders (types B and C). The clinician should be aware of the initial stresses and movements from different expanders with facemask found in this study and confirm the movements in future clinical Class III studies.

Stresses and Strains Analysis Using Different Palatal Expander Appliances in Upper Jaw and Midpalatal Suture.

Rapid maxillary expansion (RME) is the technique of increasing the transverse dimension of the upper jaw using lateral forces applied by palatal expander. Usually, this palatal appliance is anchored on posterior teeth. The purposes of this computer simulation study were to analyze the stress and strain distribution generated in the maxilla, mainly in midpalatal suture (MPS), during RME by tooth-borne and bone-borne expanders and to study the correlation between mechanical strain and Wolff's Law. The analysis was performed with finite element models developed based on Cone Beam computed tomography (CT). To simulate the expansion load, displacements were applied concerning one (0.125 mm) and three (0.375 mm) activations in the medial sides of the tooth-borne expander, and one activation (0.125 mm) for miniscrews (MSIs) in transverse and lateral direction. It was observed that to obtain approximately the same spacing in the MPS activating once the expander with bone support, three activations for the tooth-borne were necessary. However, the strain level caused by bone-borne expansion, when applying a single activation, reached 900 and 5000 μɛ, with peaks up to 20000 μɛ, in a region very close to the MSIs. Comparing the results, bone-borne appliance anchorage in the palatine bone is more effective than tooth-borne expander. Nevertheless, the stresses and strains increased significantly in the entire jaw when the bone-borne expander is used.

Condylar positional changes in rapid maxillary expansion assessed with cone-beam computer tomography.

The aim of this study was to determine the presence of condylar spatial changes in patients having rapid maxillary expansion treatments compared to a control group. Thirty-seven patients with maxillary transverse deficiency (11-17 years old) were randomly allocated into two groups (one treatment group -tooth borne expander [hyrax]- and one control group). Cone-beam computer tomographies (CBCT) were obtained from each patient at two time points (initial T1 and at removal of appliance at 6 months T2). CBCTs were analyzed using AVIZO software and landmarks were placed on the upper first molars and premolars, cranial base, condyles and glenoid fossa. Descriptive statistics, intraclass correlation coefficients and one-way Anova analysis were used to determine if there was a change in condyle position with respect to the glenoid fossa and cranial base and if there was a statistically significant difference between groups. Descriptive statistics show that changes in the condyle position with respect to the glenoid fossa were minor in both groups (<1.9mm average for both groups). The largest difference in both groups was found when measuring the distance between the left and right condyle heads. When comparing changes between both groups, no statistically significant difference was found between changes in the condyles (P<0.05). Rapid maxillary expansion treatments present mild effects/changes on the condylar position. Nevertheless, these changes do not present a significant difference with controls, thus not constituting a limitation for applying this treatment.

Cone beam computed tomography evaluation after palatal expansion and orthodontics

BackgroundRapid palatal expansion (RPE) is accepted as a valid and effective method in the correction of different types of malocclusions. An understanding of the long-term effects of RPE to the buccal plate is critical. ObjectiveThe purpose of this study was to evaluate and compare dentoalveolar changes, using cone beam computed tomography (CBCT) images, to the maxillary first premolars and permanent first molars from initial to more than 6 months in retention after comprehensive orthodontics where a hyrax tooth-borne expander was used. MethodsThe CBCTs on 14 patients were evaluated at three time points: before treatment, 3 months after palatal expansion, and more than 6 months in retention after comprehensive orthodontics. ResultsGreater tipping and greater crest height recession were observed at the first premolars. There was significant recovery of buccal plate thickness for both teeth after RPE and orthodontics. ConclusionsOne can expect significant recovery after active treatment, long term, after rapid palatal expansion. There were no clinical differences between the rapid and slow expansion groups.