Buccal bone plate thickness after rapid maxillary expansion in mixed and permanent dentitions

Biomechanical behavior of three maxillary expanders in cleft lip and palate: a finite element study

This study evaluated the stress distribution in the dentoalveolar and palatal bone structures during maxillary expansion in a 17-year-old male patient with bilateral cleft lip and palate (BCLP) using expanders with dental (HYRAX) and skeletal anchorage (MARPE). For the generation of the specific finite element models, cone-beam computed tomography was used, and the DICOM files were exported to Mimics 3-Matic (Materialise) and Patran (MSC Software) software. Three specific three-dimensional models were generated: A) HYRAX: conventional four-banded hyrax screw (9 mm); B) MARPE-DS: 3 miniscrews (1.8 mm diameter - 5.4 mm length) and four-banded dental anchorage; and C) MARPE-NoDS: 3 miniscrews without dental anchorage. Maxillary expansion was simulated by activating the expanders transversely 1 mm on the "X" axis. HYRAX resulted in higher levels of deformation predominantly in the dentoalveolar region. MARPE-DS showed stress in the dentoalveolar region and mainly in the center of the palatal region, at approximately 4,000 με. MARPE-NoDS exhibited evident stress only in the palatal region. High stress levels in the root anchoring teeth were observed for HYRAX and MARPE-DS. In contrast, MARPE-NoDS cause stress on the tooth structure. The stress distribution from the expanders used in the BLCP showed asymmetric expansive behavior. During the initial activation phase of expansion, the HYRAX and MARPE-DS models produced similarly high strain at the dentoalveolar structures and upper posterior teeth displacement. The MARPE-NoDS model showed restricted strain on the palate.

Effects of rapid maxillary expansion on anchorage alveolar bone meta-analysis

PURPOSE

Rapid maxillary expansion (RME) is a routine method for correcting transverse maxillary deficiency. This paper investigated the effect of RME on anchorage alveolar bone and examined the differences between micro-implant-assisted RME and conventional RME.

METHODS

Relevant articles were selected from the PubMed, EMBASE and Cochrane Central Register of Controlled Trials databases. Review Manager software (v.5.3) was used for the pooled analysis and Cochran Q and I2 statistic tests were used to assess the heterogeneity.

RESULTS

Following conventional RME, the distal buccal alveolar bone thickness and the mesiobuccal alveolar thickness of the maxillary first molars were significantly reduced. Hyrax (standard mean difference [SMD]: -0.93, 95% confidence interval [CI]: -1.20-0.66) and Haas procedures (SMD: -0.88, 95% CI: -1.40-0.36) significantly reduced the buccal vertical alveolar height of the maxillary first molars. Similar results were obtained for the maxillary first premolars following RME. The thickness of the buccal alveolar bone decreased with conventional RME compared to when using the method assisted by micro-implants.

CONCLUSIONS

Conventional RME can reduce the thickness and vertical height of maxillary alveolar bone, and there is less loss of alveolar bone when using micro-implant-assisted RME. Further research is needed to validate the findings.

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.

Age-dependent effects on palate volume and morphology during orthodontic RME treatment

OBJECTIVES

Rapid maxillary expansion (RME) shows different age-dependent effects. It has been shown that RME leads to a parallel expansion prior to the age of 10, while later and especially from the age of 12, a V-shaped expansion happens (transverse, anterior > posterior; horizontal, inferior > superior). However, it is not clear to what extent these effects influence palatal volume and morphology and eventually maxillary functional space. The aim of the present study was to examine possible age-related effects of treatment with a dental anchored RME appliance upon volume and width/height ratio of the anterior and posterior palate.

MATERIALS AND METHODS

Sixty children and adolescents with documented treatment histories after RME were divided into three equal groups according to age at treatment begin (PG 1, < 10 years, n=20; PG 2, 10 ≤ 12 years, n=20; PG 3, > 12 years, n=20). Maxillary dental casts before and after therapy were digitised. Changes in palatal volume were determined using 3D analyses.

RESULTS

In all patients, the palatal volume increases significantly after RME. Older patients experienced smaller increases in total and posterior volume in absolute and percentage terms. The anterior palate volume increases are almost equal in all patients. Since palatal width increases more markedly than palatal height, the width/height ratio always increases. Except for the posterior region in PG 3, its increase is significant in all groups, both anteriorly and posteriorly. After successful RME, the palatal morphology appears normal anteriorly in PG 1, PG 2 and PG 3 and rather steep posteriorly in PG 3.

CONCLUSIONS

RME treatment with identical force application causes different, age-dependent effects upon palate volume and morphology. Width changes have a greater influence on palate volume than height changes.

CLINICAL RELEVANCE

It is preferable to use an RME prior to the age of 10 if homogeneous changes of the anterior and posterior palate regarding maxillary symmetry and functional space are desired.

Fractal Perspective on the Rapid Maxillary Expansion Treatment; Evaluation of the Relationship Between Midpalatal Suture Opening and Dental Effects

OBJECTIVE

This retrospective study investigates the relationship between the midpalatal suture opening and the dental effects of Rapid Maxillary Expansion (RME) treatment using fractal analysis.

METHODS

The participants of this study were selected from the patients who underwent Cone Beam Computed Tomography(CBCT) scans in 2019 and were treated with banded type Maxillary Expander. This study included 20 participants (with a mean age of 10.64±10.64, ranging from 8 to 13 years): 12 males and 8 females. Patients went through CBCT scan and images taken were analyzed using the ImageJ program. The following parameters were measured and analyzed before and after RME treatment: fractal dimensional value of Midpalatal suture(MPS), Distobuccal(DB), Mesiobuccal(MB), Palatal(P), Total distance, Cortical bone and linear values of External maxilla, Internal maxilla, Palatal roots, distance of Central fosses and angular values of Tipping value of 16 and 26. We used Spearman's nonparametric test for non-normal variables to investigate the correlation between changes in MPS and other variables.

RESULTS

The results showed a strong positive correlation between the MPS and Right MB (0.34, p<0.05) and Left MB (0.59, p<0.05) variables and a strong negative correlation between the MPS and the External maxillary variables (-0.53, p<0.05).

CONCLUSION

The results of the study have shown a strong correlation between right and left MB and External Maxilla. RME caused a reduction in buccal alveolar bone thickness and a slight reduction in MPS thickness in growing patients. Therefore, we suggest that fractal analysis can be used to evaluate the skeletal and dental effects of RME in patients.

CBCT Analysis of Dento-Skeletal Changes after Rapid versus Slow Maxillary Expansion on Deciduous Teeth: A Randomized Clinical Trial

The aim of the present study was to compare skeletal and dental changes after rapid maxillary expansion (RME) and slow maxillary expansion (SME) performed by a Leaf Expander (LE) with upper deciduous teeth as anchorage and using 3D CBCT (Cone Beam Computed Tomography) analysis. Mixed dentition patients were randomly divided in two groups, according to the different expansion used anchored on maxillary primary second molars: the RME group (n = 16) was treated with a Hyrax type expander, whereas the SME group (n = 16) was treated with an LE expander. CBCT scans were performed before (T1) and after treatment (T2) and analyzed with a custom landmarks system. A paired t-test was used for intragroup analysis between T1 and T2, and a Student t-test was used for intergroup analysis; statistical significance was set at 0.05. Both RME and SME groups showed a statistically significant increase in dental and skeletal diameters. Group comparisons between T1 and T2 showed a significant expansion rate in the RME group for upper permanent molars (p = 0.025) but not for deciduous molars (p = 0.790). Moreover, RME showed higher increases for skeletal expansion evaluated at nasal walls (p = 0.041), whereas at pterygoid plates did not show any significant differences compared with the SME group (p = 0.849). A significant transverse expansion could be achieved with the expander anchored on deciduous teeth. RME and SME produced effective both skeletal and dentoalveolar transverse expansion; RME produced more anterior expansion than SME but less control regarding the permanent molar decompensation. SME by LE therefore could be an efficient and helpful alternative in the treatment of transverse maxillary deficiency in growing patients.

Dehiscence and buccal bone thickness after rapid maxillary expansion in young patients with unilateral cleft lip and palate

INTRODUCTION

The present study aimed to evaluate the consequences of rapid maxillary expansion in the buccal bone thickness and dehiscence of subjects with unilateral cleft lip and palate.

METHODS

This prospective cohort study consisted of 30 participants, 20 males and 10 females, between 8 and 15 years old. Participants were allocated into 3 groups, according to the type of maxillary constriction, and were treated with different types of expanders: G1, hyrax; G2, fan-type; G3, inverted mini-hyrax. Cone-beam computed tomography scans were performed immediately before treatment and after 90 days of retention. Linear measurements were obtained by the same calibrated and blinded examiner.

RESULTS

An average of 0.8 mm decrease in buccal bone thickness (P <0.001) and a 0.5 mm increase in dehiscence (P <0.001) were observed. There was no significant difference between the cleft and noncleft side for all variables (P >0.05), as there was no significant difference between groups (P >0.05).

CONCLUSION

The findings in this study allow the conclusion that the orthopedic forces of rapid maxillary expansion lead to a decrease in the posterior buccal bone volume in unilateral cleft lip and palate patients.

Effect of Low-Intensity Pulsed Ultrasound (LIPUS) on Alveolar Bone during Maxillary Expansion Using Clear Aligners

The present study evaluated the possible effect of low-intensity pulsed ultrasound (LIPUS) on buccal bone plate thickness and height after maxillary arch expansion using clear aligners. The cone beam computed tomography (CBCT) of before and immediately after maxillary arch expansion (3 mm per side) of 28 adult patients (18 in LIPUS group and 10 in control) (average age $36.2\pm 13.2$ years old) was analyzed. The wearing protocol of clear aligners in the LIPUS group was to change the aligners every 4 to 5 days, while the wearing protocol in the control group (without LIPUS) was to change the aligners every 7 to 10 days. Bone thickness at 3 mm and 6 mm from the buccal alveolar bone crests, along with the measurements of buccal alveolar bone heights, was measured in standardized sagittal sections. Data were analyzed through paired sample $t$ -test and the Wilcoxon test. The results were given as $\text{mean}\pm \text{standard}\text{deviation}$ and 95% confidence intervals. $p$ value < 0.05 was considered statistically significant. The results showed significant increase in bone height in both groups. However, comparison of both LIPUS and control groups showed no statistically significant difference in bone thickness or bone height. The results of this study showed that the use of LIPUS together with accelerated aligner tray change protocol did not affect alveolar bone integrity when compared to the control group.

Orthodontic treatment for posterior crossbites

BACKGROUND

A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth. The prevalence of posterior crossbite is around 4% and 17% of children and adolescents in Europe and America, respectively. Several treatments have been recommended to correct this problem, which is related to such dental issues as tooth attrition, abnormal development of the jaws, joint problems, and imbalanced facial appearance. Treatments involve expanding the upper jaw with an orthodontic appliance, which can be fixed (e.g. quad-helix) or removable (e.g. expansion plate). This is the third update of a Cochrane review first published in 2001.

OBJECTIVES

To assess the effects of different orthodontic treatments for posterior crossbites.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched four bibliographic databases up to 8 April 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of orthodontic treatment for posterior crossbites in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, screened the results of the electronic searches, extracted data, and assessed the risk of bias of the included studies. A third review author participated to resolve disagreements. We used risk ratios (RR) and 95% confidence intervals (CIs) to summarise dichotomous data (event), unless there were zero values in trial arms, in which case we used odds ratios (ORs). We used mean differences (MD) with 95% CIs to summarise continuous data. We performed meta-analyses using fixed-effect models. We used the GRADE approach to assess the certainty of the evidence for the main outcomes.

MAIN RESULTS

We included 31 studies that randomised approximately 1410 participants. Eight studies were at low risk of bias, 15 were at high risk of bias, and eight were unclear. Intervention versus observation For children (age 7 to 11 years), quad-helix was beneficial for posterior crossbite correction compared to observation (OR 50.59, 95% CI 26.77 to 95.60; 3 studies, 149 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 4.71 mm, 95% CI 4.31 to 5.10; 3 studies, 146 participants; moderate-certainty evidence). For children, expansion plates were also beneficial for posterior crossbite correction compared to observation (OR 25.26, 95% CI 13.08 to 48.77; 3 studies, 148 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 3.30 mm, 95% CI 2.88 to 3.73; 3 studies, 145 participants, 3 studies; moderate-certainty evidence). In addition, expansion plates resulted in higher inter-canine distances (MD 2.59 mm, 95% CI 2.18 to 3.01; 3 studies, 145 participants; moderate-certainty evidence). The use of Hyrax is probably effective for correcting posterior crossbite compared to observation (OR 48.02, 95% CI 21.58 to 106.87; 93 participants, 3 studies; moderate-certainty evidence). Two of the studies focused on adolescents (age 12 to 16 years) and found that Hyrax increased the inter-molar distance compared with observation (MD 5.80, 95% CI 5.15 to 6.45; 2 studies, 72 participants; moderate-certainty evidence). Intervention A versus intervention B When comparing quad-helix with expansion plates in children, quad-helix was more effective for posterior crossbite correction (RR 1.29, 95% CI 1.13 to 1.46; 3 studies, 151 participants; moderate-certainty evidence), final inter-molar distance (MD 1.48 mm, 95% CI 0.91 mm to 2.04 mm; 3 studies, 151 participants; high-certainty evidence), inter-canine distance (0.59 mm higher (95% CI 0.09 mm  to 1.08 mm; 3 studies, 151 participants; low-certainty evidence) and length of treatment (MD -3.15 months, 95% CI -4.04 to -2.25; 3 studies, 148 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and Haas for posterior crossbite correction (RR 1.05, 95% CI 0.94 to 1.18; 3 studies, 83 participants; moderate-certainty evidence) or inter-molar distance (MD -0.15 mm, 95% CI -0.86 mm to 0.56 mm; 2 studies of adolescents, 46 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and tooth-bone-borne expansion for crossbite correction (RR 1.02, 95% CI 0.92 to 1.12; I² = 0%; 3 studies, 120 participants; low-certainty evidence) or inter-molar distance (MD -0.66 mm, 95% CI -1.36 mm to 0.04 mm; I² = 0%; 2 studies, 65 participants; low-certainty evidence).  There was no evidence of a difference between Hyrax with bone-borne expansion for posterior crossbite correction (RR 1.00, 95% CI 0.94 to 1.07; I² = 0%; 2 studies of adolescents, 81 participants; low-certainty evidence) or inter-molar distance (MD -0.14 mm, 95% CI -0.85 mm to 0.57 mm; I² = 0%; 2 studies, 81 participants; low-certainty evidence).  AUTHORS' CONCLUSIONS: For children in the early mixed dentition stage (age 7 to 11 years old), quad-helix and expansion plates are more beneficial than no treatment for correcting posterior crossbites. Expansion plates also increase the inter-canine distance. Quad-helix is more effective than expansion plates for correcting posterior crossbite and increasing inter-molar distance. Treatment duration is shorter with quad-helix than expansion plates. For adolescents in permanent dentition (age 12 to 16 years old), Hyrax and Haas are similar for posterior crossbite correction and increasing the inter-molar distance. The remaining evidence was insufficient to draw any robust conclusions for the efficacy of posterior crossbite correction.

Buccal Bone Thickness in Anterior and Posterior Teeth-A Systematic Review

(1) Background: Immediate dental implant placement has been a subject of great interest over the last decade. Here, information regarding the anatomy and bone thickness of the jaw prior to dental implant placement is crucial to increase the surgery's success and the patient's safety. The clinical premises for this approach have been controversially discussed. One of those heavily discussed premises is a buccal bone thickness of at least 1 mm thickness. This meta-analysis aims to systematically review buccal bone thickness (BBT) in healthy patients. Thus, the feasibility of immediate dental implant placement in daily practice can be assessed. (2) Methods: A search in the electronic databases was performed to identify articles reporting on BBT that was measured by computed tomography in adults. (3) Results: We were able to find 45 studies, including 4324 patients with 25,452 analyzed teeth. The analysis showed a BBT at the alveolar crest of 0.76 ± 0.49 mm in the maxillary frontal and of 1.42 ± 0.74 mm in the maxillary posterior region. In the mandible, the average measured values were similar to those in the maxilla (front: 0.95 ± 0.58 mm; posterior: 1.20 ± 0.96 mm). In the maxillary frontal region 74.4% and in the mandibular frontal region 61.2% of the crestal buccal bones showed widths <1 mm. (4) Conclusions: In more than 60% of the cases, the BBT at the alveolar crest is <1 mm in maxillary and mandibular frontal regions. This anatomic data supports careful pre-surgical assessment, planning of a buccal graft, and critical selection of indication for immediate implant placement, especially in the maxillary and mandibular frontal and premolar region.

Factors related to maxillary expander loss due to anchoring deciduous molars exfoliation during treatment in the mixed dentition phase

OBJECTIVES

The aim was to identify factors associated with maxillary expander loss due to anchoring deciduous molars exfoliation and assess the diagnostic accuracy of the upper second premolar cusp position as a prognostic factor for the exfoliation of its corresponding deciduous molar.

MATERIALS/METHODS

Ninety-two subjects aged 8.4 ± 1.1 years, treated with a Haas or hyrax expander, and using the same expansion protocol and deciduous teeth as anchorage were included. The position of the upper second premolar cusp, according to the half pulp chamber (HPC) line of the ipsilateral upper first permanent molar, was assessed on pre-treatment panoramic radiographs.

RESULTS

A significant association between anchoring deciduous molar exfoliation and the position of the upper second premolar cusp according to the HPC line (P = 0.002; odds ratio = 5.7) was seen, while there was no association with gender, age, treatment duration, and type of expander. The median survival time for an anchoring deciduous molar, when the underlying premolar cusp was touching/crossing the HPC line, was 13.0 (11.7; 14.2) months. The upper second premolar cusp position to the HPC line showed high accuracy (at least 76.11 per cent) and substantial repeatability (at least 0.7) as a prognostic factor for the corresponding second deciduous molar exfoliation.

LIMITATIONS

Applicability in the mixed dentition phase with fully erupted upper first permanent molars.

CONCLUSIONS

The probability of a second deciduous molar to be successfully used as maxillary expander anchorage for at least 16 months is above 94 per cent; when at baseline, the corresponding premolar cusp is apical to the HPC line.

Comparison of skeletal and dentoalveolar changes between pure bone-borne and hybrid tooth-borne and bone-borne maxillary rapid palatal expanders using cone-beam computed tomography

Objectives:

The objectives of the study were to compare the skeletal, dentoalveolar, and periodontal changes between two types of microimplant-assisted rapid maxillary expansion appliances: The bone-anchored maxillary expanders (BAME) and the tooth-bone-anchored maxillary skeletal expander (MSE).

Materials and Methods:

Thirty-four patients with a transverse maxillary deficiency were divided into two groups; the first group (16 patients, average age 14.9 years) was treated with the MSE appliance, and the second group (18 patients, average age 13.8 years) was treated with the BAME appliance. Cone-beam computed tomography scans were taken at pre-treatment (T1) and immediately post-expansion (T2) to measure the changes in midpalatal suture opening, total expansion (TE), alveolar bone bending, dental tipping (DT), and buccal bone thickness. Data were analyzed using paired t-test and two-sample t-test.

Results:

Midpalatal suture separation was found in 100% of the patients in both groups. The TE at the first molar was 5.9 mm in the MSE group and 4.7 mm in the BAME group. The skeletal contributions were 56% and 83% of TE for the MSE and BAME groups, respectively. Significantly less dental buccal tipping and buccal bone loss were found with the BAME group. The midpalatal suture in both groups exhibited a parallel opening pattern in the axial plane.

Conclusion:

The use of BAME appliance resulted in greater skeletal effects, less dental tipping, and less buccal bone reduction compared to MSE appliance (immediately after maxillary expansion).

Evaluation of mandibular changes after rapid maxillary expansion: a CBCT study in youngsters with unilateral posterior crossbite using a surface-to-surface matching technique

OBJECTIVES

The purpose of this study was to evaluate mandibular asymmetry in youngsters with posterior unilateral crossbite (PUXB), through cone-beam computed tomography and reverse engineering technique, before and after rapid maxillary expansion (RME) treatment.

MATERIALS AND METHODS

Forty cone-beam computed tomography (CBCT) images were obtained from all patients at two time points, namely T0 acquired before the placement of a Hyrax expander and T1 after appliance removal. The CBCT scans were segmented and volume rendered into a surface there-dimensional (3D) mesh model. Thereafter, mandibular models were digitally registered by using a "best-fit" algorithm. Surface and volumetric changes, between T0 and T1, were compared by using Student's t tests.

RESULTS

A slight increase of 0.45 cm³ of the total mandibular volume was found at T1 when compared with T0 (p < 0.001). The mandibular hemi-volume on the crossbite side (CB) was slightly smaller than the non-crossbite side both at T0 and T1. However, the mean differences of hemi-volume from the CB (crossbite) and non-CB side between T0 and T1 show a decrease of 0.26 cm³ (p < 0.001). Findings for the surface-to-surface deviation analysis demonstrated a fine percentage of matching at T0 which slightly improved at T1 (p < 0.001).

CONCLUSIONS

Youngsters affected by PUXB showed a very slight and not statistically significant volumetric and morphological asymmetry between CB side and non-CB side at T0. However, the change in mean differences of 0.26 cm cannot be considered clinically relevant.

CLINICAL RELEVANCE

Mandibles in young PUXB patients exhibit only a very mild mandibular asymmetry. Although the statistically significant mean change found right after RME removal cannot be considered clinically relevant, a more consistent sample and a longer follow-up could be of interest in explaining the short-term findings.

Buccal alveolar bone changes following rapid maxillary expansion and fixed appliance therapy

OBJECTIVES

To assess factors that may be associated with buccal bone changes adjacent to maxillary first molars after rapid maxillary expansion (RME) and fixed appliance therapy.

MATERIALS AND METHODS

Pretreatment (T1) and posttreatment (T2) cone-beam computed tomography scans were obtained from 45 patients treated with RME and preadjusted edgewise appliances. Buccal alveolar bone thickness was measured adjacent to the mesiobuccal root of the maxillary first molar 4 mm, 6 mm, and 8 mm apical to the cementoenamel junction, and anatomic defects were recorded. Paired and unpaired t-tests were used to compare alveolar bone thickness at T1 and T2 and to determine whether teeth with posttreatment anatomic defects had thinner initial bone. Correlation analyses were used to examine relationships between buccal alveolar bone thickness changes and amount of expansion, initial bone thickness, age at T1, postexpansion retention time, and treatment time.

RESULTS

There was a statistically significant reduction in buccal alveolar bone thickness from T1 to T2. Approximately half (47.7%) of the teeth developed anatomic defects from T1 to T2. These teeth had significantly thinner buccal bone at T1. Reduction in alveolar bone thickness was correlated with only one tested variable: initial bone thickness.

CONCLUSIONS

RME and fixed-appliance therapy can be associated with significant reduction in buccal alveolar bone thickness and an increase in anatomic defects adjacent to the expander anchor teeth. Anchor teeth with greater initial buccal bone thickness have less reduction in buccal bone thickness and are less likely to develop posttreatment anatomic defects of buccal bone.

Diagnostic ability of the primary second molar crown-to-root length ratio and the corresponding underlying premolar position in estimating future expander anchoring teeth exfoliation

OBJECTIVES

The aim was to assess the diagnostic ability of the crown-to-root length ratio of the primary second molar and the position of the corresponding underlying premolar in estimating future anchoring teeth exfoliation during maxillary expansion.

SETTING AND SAMPLE POPULATION

Fifty-four subjects (30 females, 24 males; 108 teeth) aged 8.2 ± 1.0 years that underwent palatal expansion.

METHODS

The upper second premolar position of the corresponding expander anchoring primary molar was determined in relation to the ipsilateral first permanent molar half-pulp chamber (HPC) line on panoramic radiographs. Subjective and objective (based on measurements) assessments of the crown-to-root length ratio of anchoring primary molars were performed. Exfoliation after the expansion was recorded over a retention period of 12 months. All the assessments were performed individually by three examiners at two 3-week-apart sessions, trained and calibrated before enrolment. The intra-/inter-examiner agreements were evaluated, and the diagnostic accuracy of the methods was calculated.

RESULTS

All methods exhibited almost perfect intra- and at least substantial inter-examiner agreement (Kappa >0.8 and ≥0.63, respectively). Good diagnostic accuracy was seen for the premolar position to the HPC line (0.7-0.8), while the crown-to-root length ratio methods exhibited hardly sufficient accuracy. The diagnostic agreement of the methods was fair.

CONCLUSIONS

When primary molars are considered as anchoring teeth for maxillary expansion, the premolar position in relation to the HPC line appears to be the most valid and reliable method for predicting their stability. Despite high repeatability values, the crown-to-root length ratio needs a cut-off point re-definition to increase its predicting ability.

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.

Buccal Bone Changes Around First Permanent Molars and Second Primary Molars after Maxillary Expansion with a Low Compliance Ni-Ti Leaf Spring Expander

Background: Vestibular bone thickness changes and dento-alveolar buccal tipping of second primary molars and of first molars after maxillary expansion performed with a slow maxillary expansion protocol was investigated. Methods: Twenty patients (mean age 7.3 ± 0.9 years old; 9 male and 11 female) were treated according to the Leaf Expander protocol. Buccal alveolar bone thickness (BT), buccal alveolar bone height (BH), inter-dental angle (TIP), and inter-molar width (IW) regarding first molars and second primary molars were calculated before and after expansion on cone beam computed tomography (CBCT) images. Descriptive statistics and paired t-tests were used to assess changes between the pre-treatment and post-treatment measurements. Results: Bone thickness vestibular to second primary molars and intermolar width of both teeth were the only variables that showed statistically significant changes. Conclusions: It appears that buccal bone thickness vestibular to first molars was not significantly reduced after maxillary expansion with the Leaf Expander. The clinical use of a slow maxillary expander with Ni-Ti springs appears efficient and safe in in the correction of maxillary hypoplasia during mixed dentition.

Circummaxillary Sutures in Patients With Apert, Crouzon, and Pfeiffer Syndromes Compared to Nonsyndromic Children: Growth, Orthodontic, and Surgical Implications

OBJECTIVE

To evaluate patency of circummaxillary sutures in children with Apert, Crouzon, and Pfeiffer Syndromes and to compare it to a nonsyndromic matched control group.

DESIGN

Case-control study.

SETTING

Tertiary care public hospital.

MATERIALS AND METHODS

Thirty-eight computed tomography (CT) scans of patients affected by syndromic craniofacial synostosis (13 patients with Apert syndrome, 20 patients with Crouzon syndrome, and 5 patients with Pfeiffer syndrome), average age 5 ± 2.8 years, range 1.9 to 12 years, were compared to age- and sex-matched control CTs of 38 nonsyndromic children. Computed tomography scans of the study group had to be performed prior to any midfacial surgery.

MAIN OUTCOME MEASURES

Midpalatal suture, zygomaticomaxillary sutures, and pterigomaxillary sutures were evaluated and scored.

RESULTS

The syndromic group showed a significant earlier ossification of all sutures compared to the nonsyndromic group. Significant differences were already present in early childhood and continued through adolescence.

CONCLUSIONS

Based on the differences in terms of maxillary sutural ossification identified, midfacial hypoplasia does not seem to be only secondary to premature cranial base ossification, but also to primary synostosis of facial sutures, thus providing new insights into the pathogenesis of midface deficiency in children with craniofacial-synostosis. Care should be taken when planning any maxillary orthopedics, such as expansion or maxillary protraction, given the high frequency of early fusion of circummaxillary sutures.

Changes in canine inclination after rapid and slow maxillary expansion compared to untreated controls

OBJECTS

Palatally displaced canines (PDC) might represent condition causing several clinical problems, such as roots resorption and malocclusion, and can develop palatal canine impaction. Some interceptive treatments such as rapid maxillary expansion were suggested in order to foster maxillary canine eruption. Among expansion protocols, no data are available about differences between rapid and slow maxillary expansion on maxillary canine eruption. The aim of this study was therefore to evaluate α-angle changes in palatally displaced canines using rapid and slow maxillary expansion compared to untreated control patients.

SETTING AND SAMPLE POPULATION

The final sample comprised 19 patients treated with rapid maxillary expansion (RME group), 17 treated with slow maxillary expansion (SME group) and 22 control patients (Control group).

MATERIALS AND METHODS

α-angle was measured on panoramic films to detect canine inclination at the beginning, and at the end of maxillary expansion treatment or observation, time and changes over time were compared.

RESULTS

In the comparisons among groups, RME group was the only group showing a decrease in α-angle measurements that was statistically significant also when compared to the other groups, except for the left side when compared to SME group.

CONCLUSION

RME treatment significantly and positively affected canine position when compared to SME treatment and control group.

Upper canine response to rapid maxillary expander anchored to deciduous vs. permanent molars

PURPOSE

To understand whether two different designs of Haas-type rapid maxillary expander (H‑RME) might have a different influence on canine eruption.

PATIENTS AND METHODS

In all, 108 subjects seeking orthodontic treatment were selected and divided into two groups-H‑RME with bands on the upper second deciduous molars (GrE), H‑RME with bands on the upper first permanent molars (Gr6)-and were also compared to an historical untreated control group (CG) of 29 subjects. Panoramic x‑rays (OPG) were performed before and after RME (T0-T1: 16 ± 7 months) and the upper canine angulation to the midline ("α" angle) was measured on both pre- and posttreatment OPG.

RESULTS

A significant improvement of the canine position (decrease of the α angle) following RME in subjects with mixed dentition was reported in both treated groups, although the different design of the RME did not significantly affect canine angulation. Canine angulation in untreated subjects with transversal discrepancy did not improve significantly.

CONCLUSION

Using RME in the early mixed dentition appears to be an effective procedure to increase the rate of eruption of maxillary canines, but the position of the bands on the upper second deciduous molars or on the upper first permanent molars and the significant different expansion of the upper dental arch at the canine level does not significantly influence the canine angulation following early treatment therapy.