Three-dimensional skeletal and dentoalveolar sagittal and vertical changes associated with cantilever Herbst appliance in prepubertal patients with Class II malocclusion

INTRODUCTION

This study aimed to assess sagittal and vertical skeletal and dentoalveolar changes through the use of 3-dimensional imaging in prepubertal Class II malocclusion patients treated with a cantilever Herbst appliance (HA). Condyle-glenoid fossa positional changes were also quantified.

METHODS

This retrospective cohort study assessed 22 children (11.2 years ± 1.2) consecutively treated with a cantilever HA for 12 months and 11 untreated children (aged 9.3 ± 0.30 years) that served as controls. Cone-beam computed tomography was performed at baseline (T1) and at the end of the observation period (T2). Movements in the regions of interest were measured as linear displacements from cone-beam computed tomography images through algebraic calculations. A Student t test for independent samples was used for group equivalence testing at T1, and the treatment differences between T2 and T1 were evaluated by 2 analyses of covariance, one considering the expected growth unit as a covariate and the other with an annualized factor.

RESULTS

The largest dental movement was a mesial movement of mandibular molars (3.70 mm), whereas the largest skeletal changes consisted of a larger relative length of the mandible (difference of 1.2 mm) in the HA group than in the control group.

CONCLUSIONS

Within the study limitations (retrospective cohort, historical control group, and sample size), 3-dimensional imaging suggests that HA corrected Class II malocclusion in a predominantly prepubertal sample through more dental than skeletal changes. The changes were more significant in the sagittal than in the vertical direction. In addition, relative stability in the condyle-fossa relationship was noted.

Periodontal effects of maxillary expansion in adults using non-surgical expanders with skeletal anchorage vs. surgically assisted maxillary expansion: a systematic review

OBJECTIVES

Describe and compare harmful periodontal effects as a consequence of maxillary expansion in adult patients with different types of anchorage devices in non-surgical expanders with skeletal anchorage and surgically assisted maxillary expansion.

MATERIALS AND METHODS

An exhaustive search was carried out on the electronic databases PubMed (MEDLINE), Embase, Cochrane and LILACS. Additionally, journal references and grey literature were searched without any restrictions. After the selection and extraction process; risk of bias was assessed by the ROB-1 Cochrane tool and Newcastle-Ottawa Scale (NOS) for randomized trials and cohort studies, respectively.

RESULTS

Of 621 studies retrieved from the searches, six were finally included in this review. One of them presented a low risk bias, while five were excellent respective to selection, comparability and outcomes. Results showed that maxillary expansion in adults using non-surgical expanders (bone-borne or tooth-bone-borne with bicortical skeletal anchorage) produce less harmful periodontal effects, such as: alveolar bending with an average range from 0.92° to 2.32°, compared to surgically assisted maxillary expansion (tooth-borne) of 6.4°; dental inclination with an average range from 0.07° to 2.4°, compared to surgically assisted maxillary expansion (tooth-borne) with a range from 2.01° to 5.56°.

CONCLUSIONS

Although limited, the current evidence seems to show that the bone-borne or tooth-bone-borne with bicortical skeletal anchorage produces fewer undesirable periodontal effects.

Comparison of Skeletal and Dental Changes Obtained from a Tooth-Borne Maxillary Expansion Appliance Compared to the Damon System Assessed through a Digital Volumetric Imaging: A Randomized Clinical Trial

The purpose of this study was to evaluate and compare dental and skeletal changes associated with the Damon and Rapid Maxillary Expander (RME) expansion using Cone-Beam Computed Tomography (CBCT). Eighty-two patients, from The University of Alberta Orthodontic Clinic, were randomly allocated to either Group A or B. Patients in Group A received orthodontic treatment using the Damon brackets. Patients in Group B received treatment using the Hyrax (a type of RME) appliance. CBCT images were taken two times (baseline and after expansion). The AVIZO software was used to locate 18 landmarks (dental and skeletal) on sagittal, axial, and coronal slices of CBCT images. Comparison between two groups showed that transverse movement of maxillary first molars and premolars was much greater in the Hyrax group. The lateral movements of posterior teeth were associated with buccal tipping of crowns. No clinically significant difference in the vertical or anteroposterior direction between the two groups was noted. Alveolar bone next to root apex of maxillary first premolar and molar teeth showed clinically significant lateral movement in the Hyrax group only. The comparison between two groups showed significantly greater transverse expansion of the first molar and first premolars with buccal tipping in the RME group.

One Step before 3D Printing-Evaluation of Imaging Software Accuracy for 3-Dimensional Analysis of the Mandible: A Comparative Study Using a Surface-to-Surface Matching Technique

The accuracy of 3D reconstructions of the craniomaxillofacial region using cone beam computed tomography (CBCT) is important for the morphological evaluation of specific anatomical structures. Moreover, an accurate segmentation process is fundamental for the physical reconstruction of the anatomy (3D printing) when a preliminary simulation of the therapy is required. In this regard, the objective of this study is to evaluate the accuracy of four different types of software for the semiautomatic segmentation of the mandibular jaw compared to manual segmentation, used as a gold standard. Twenty cone beam computed tomography (CBCT) with a manual approach (Mimics) and a semi-automatic approach (Invesalius, ITK-Snap, Dolphin 3D, Slicer 3D) were selected for the segmentation of the mandible in the present study. The accuracy of semi-automatic segmentation was evaluated: (1) by comparing the mandibular volumes obtained with semi-automatic 3D rendering and manual segmentation and (2) by deviation analysis between the two mandibular models. An analysis of variance (ANOVA) was used to evaluate differences in mandibular volumetric recordings and for a deviation analysis among the different software types used. Linear regression was also performed between manual and semi-automatic methods. No significant differences were found in the total volumes among the obtained 3D mandibular models (Mimics = 40.85 cm³, ITK-Snap = 40.81 cm³, Invesalius = 40.04 cm³, Dolphin 3D = 42.03 cm³, Slicer 3D = 40.58 cm³). High correlations were found between the semi-automatic segmentation and manual segmentation approach, with R coefficients ranging from 0,960 to 0,992. According to the deviation analysis, the mandibular models obtained with ITK-Snap showed the highest matching percentage (Tolerance A = 88.44%, Tolerance B = 97.30%), while those obtained with Dolphin 3D showed the lowest matching percentage (Tolerance A = 60.01%, Tolerance B = 87.76%) (p < 0.05). Colour-coded maps showed that the area of greatest mismatch between semi-automatic and manual segmentation was the condylar region and the region proximate to the dental roots. Despite the fact that the semi-automatic segmentation of the mandible showed, in general, high reliability and high correlation with the manual segmentation, caution should be taken when evaluating the morphological and dimensional characteristics of the condyles either on CBCT-derived digital models or physical models (3D printing).

Long term skeletal and dental changes between tooth-anchored versus Dresden bone-anchored rapid maxillary expansion using CBCT images in adolescents: Randomized clinical trial

OBJECTIVE

The aim of this study was to determine long-term skeletal and dental changes in tooth-anchored versus Dresden bone-anchored rapid maxillary expansion using CBCT images in adolescents.

MATERIALS AND METHODS

In all, 29 adolescent patients (11-17 years of age) needing skeletal expansion were randomly allocated to two different groups treated by either a Dresden bone-anchored expander or a conventional hyrax expander. Patients included did not have previous orthodontic treatment, were non-syndromic and had all teeth present in mouth. CBCT images were taken before expansion and two or more years after expansion. An independent T-test was used to determine the statistical significance between treatment groups and paired T-test was used to compare the results before and after expansion in each group.

RESULTS

Neither treatment group showed overall long-term different skeletal and dental changes in the transverse, anterior-posterior and vertical planes (P<0.05). Both treatment groups showed mild asymmetric skeletal expansion, but these were clinically insignificant.

CONCLUSIONS

Both expanders had similar skeletal and dental results. The greatest changes were in the transverse plane. Changes in vertical and anterior-posterior were negligible.

Shear bond strength of a flash-free orthodontic adhesive system after thermal aging procedure

In this article by Carlos and colleagues (J Clin Exp Dent. 2019 Feb 1;11(2):e154-61), there is an error in the Material and Methods of the abstract. The correct Material and Methods of the abstract is: Material and Methods: A total of 120 human premolars were randomly divided into two groups (n=60) according to the orthodontic adhesive used: APC Flash-Free Adhesive Coated Appliance System (APC FF) or Transbond PLUS Color Change Adhesive (TP), as control. A SBS test was performed and ARI value for each specimen was also assessed. Results were analyzed by two-way ANOVA and Tukey's Chi-square test (p<0.05).

Dental and skeletal changes associated with the Damon system philosophical approach

OBJECTIVE

To compare the skeletal and dentoalveolar changes produced by the Damon system's treatment philosophy to traditional orthodontic treatment techniques.

MATERIALS AND METHODS

An electronic search in four major databases was completed: Cochrane, PubMed, EMBASE, and Google Beta Scholar on October 5th, 2018. Randomized controlled trials, prospective and retrospective controlled clinical trials were included in this systematic review. The quality assessment of individual studies was done using two different tools: The Cochrane Risk of Bias Assessment Tool (RTCs) and The Methodological Index for Non-Randomized Studies (MINORS) (non-RCTs).

RESULTS

Seven studies were included for this qualitative analysis. Six studies compared the Damon system to various types of conventional (non self-ligating bracket) system as a comparison group. One study used a quad helix as a comparison for a few months before a full bonding appointment with conventional brackets. The majority of studies found an increase in maxillary inter-canine, inter-premolar, and intermolar distance after the treatment in both the Damon and comparison groups. Yet, all studies concluded that there is no significant difference in the final transverse dimension between the two groups. One study also found that the transverse expansion was achieved mainly by tipping movement of posterior dentition, and a decrease in the posterior buccal bone area was evident in both groups after treatment.

CONCLUSION

There is not enough evidence to support the claim that the Damon system allows additional arch expansion with better tipping control than with traditional techniques.

Effect of photobiomodulation on the stability and displacement of orthodontic mini-implants submitted to immediate and delayed loading: a clinical study

The aim of this study was to evaluate the effect of photobiomodulation (PBM) on the stability and displacement of orthodontic mini-implants (MIs) submitted to loading. Forty-eight and 35 mini-implants (1.5 × 8 × 1 mm) were assessed for stability and displacement, respectively (19 patients). MIs were allocated according to the intervention in 1-PBM + immediate loading (IL), 2-PBM + delayed loading (DL) (four weeks after implantation), 3-IL only, and 4-DL only. PBM (Therapy XT, DCM) was implemented using a red emission (660 nm, 4 J/cm², 0.1 W, 20 s) immediately after implantation (day 0) and infrared emissions (808 nm; 8 J/cm², 0.1 W, 40 s) in the following appointments every 48-72 h during two weeks (days 2, 4, 7, 9, 11, and 14). Loading of 150 gF was applied during three months for all MIs. The stability was assessed by resonance frequency analysis (Osstell ISQ), and images from Cone beam computed tomography were evaluated to determine the amount of the displacement of the MI's head. MIs from the PBM groups presented lower loss of stability (P = 0.0372). When the analysis considered the loading protocol as an additional variable, group two showed the lowest loss of stability, being significantly different from groups that did not receive PBM (P = 0.0161). There was no difference between groups two and four during the period without loading (P > 0.05). DL groups presented lower loss when the effective period of loading was assessed, independently of the application of PBM (P < 0.0001). All groups showed displacement of the MIs head without significant differences (P > 0.05). DL potentiated the effect of PBM, decreasing the loss of stability.

Antero-posterior mandibular position at different vertical levels for mandibular advancing device design

INTRODUCTION

Mandibular Advancement Devices (MAD) have been reported to be an alternative treatment to CPAP in moderate to severe obstructive sleep apnea (OSA) cases. The design of MAD has a major influence on its success rate on the patient, and design features that have an influence on efficacy, tolerance, and compliance. The aim of this study was to determine the range of mandibular protrusion at different vertical points; 2, 5, 8 and 11 mm in a young adult population.

METHODS

Fifty two students aged 19 to 23 years (mean 21.3 ± 1.7; 29 females and 23 males), with full permanent dentition participated in the study. The absolute range of maximal mandibular protrusion and retrusion was measured (mm) with the use of the George Gauge. Descriptive statistics, ANOVA and paired t-test using SPSS were used.

RESULTS

Range of mandibular advancement was possible to be determined for the 4 levels of vertical opening with the gauges: 2 mm fork mean mandibular advance 13,10 mm ± 0.604; 5 mm mean 11.98 mm ± 1.075; 8 mm mean 11.20 mm ± 1.369; 11 mm mean 9.87 mm ± 1.886. No significant differences were found between class I, II, and III.

CONCLUSIONS

There is an impact of increased inter-incisal distance of effective mandibular protrusion when constructing a MAD. As vertical dimension increases the mandible rotates posteriorly and places itself in a more retrusive location, and the range of mandibular advancement reduces (0.3 mm for every 1 mm of vertical increase).

Three-dimensional skeletal and dental patterns obtained from cone-beam computer tomography of patients diagnosed as malocclusion class I

The purpose of this study was to locate the landmarks both in traditionally-used two-dimensional (2D) lateral cephalogram images and newly suggested landmarks in three-dimensional (3D) cone-beam computer tomography (CBCT) images to determine possible relationships between them and determine if they could be used to classify patients of malocclusion Class I.

MATERIAL AND METHODS

CBCT images from 30 patients with malocclusion Class I were selected from the university of Alberta Graduate Orthodontic Program database. The images were then reconstructed using the AVIZO^® software platform to visualize and locate landmarks. There were a total of forty-two landmarks chosen for analysis, which included pre-existing landmarks used in 2D imaging as well as new landmarks suggested for 3D analysis. Descriptive statistics were also assessed using SPSS statistical package to determine any skeletal and dental relationships.

RESULTS

Descriptive statistics show that the linear and angular measurements used in 2D images did not correlate well with measurements in CBCT. The lowest standard deviation obtained was 0.04 for S-GoL/N-Me with a mean of 0.70mm. The highest standard deviation was 17.46 for FH-MPL with a mean of 41.53mm.

CONCLUSION

The traditional landmarks used for 2D analysis of malocclusion did not show specific skeletal or dental patterns for analysing and classifying 3D images as malocclusion Class I.

Shear bond strength of a flash-free orthodontic adhesive system after thermal aging procedure

Background

The aim of this study was to compare the shear bond strength (SBS) of a flash-free and precoated orthodontic adhesive with a compomer orthodontic adhesive before and after thermocycling. The adhesive remnant index (ARI) was also determined for both adhesives.

Material and Methods

The adhesive remnant index (ARI) was also determined for both adhesives. Material and Methods: A total of 120 human premolars were randomly divided into two groups (n=60) according to the orthodontic adhesive used: APC Flash-Free Adhesive Coated Appliance System (APC FF) or Transbond PLUS Color Change Adhesive (TP), as control. A SBS test was performed and ARI value for each specimen was also assessed. Results were analyzed by two-way ANOVA and Tukey's Chi-square test (p<0.05).

Results

SBS values were significantly influenced by thermocycling (p<0.01). Neither the orthodontic adhesive nor the interaction between adhesive and thermocycling statistically affected SBS results (p>0.05).

Conclusions

APC FF and TP showed similar bond strength results. Thermocycling induced a significant decrease in SBS values for the two adhesives tested, without differences between 10,000 and 20,000 thermal cycles. Moreover, APC FF left less adhesive remnants on the enamel compared to TP. Key words:APC Flash-Free, APC cement, aging, orthodontics, resin cements.

United Reference Method for three-dimensional treatment evaluation

Background

Reproducible and descriptive Three-dimensional treatment evaluation can enhance future treatment based on realistic results. So, the purpose of this study was to describe a new method for three-dimensional treatment evaluation showing how to use fully-automated craniofacial superimposition of CBCT records combined with reference system to obtain descriptive and comparable results. This new method was named United Reference Method (URM).

Methods

URM is a combination of automated 3D superimposition on anterior cranial base surface anatomy and measurements based on reference system. It was developed to show how to use fully-automated superimposition to obtain descriptive numerical comparable values. The method is based on: one main reference system for both superimposed CBCT records, semi-automation to increase accuracy, all measurements are projections and auxiliary references to aid in landmarks identification and measurements.

The method steps can be described following a four-step approach: (1) Superimposition performed through a fully automated, voxel-wise, rigid registration considering only cranial base as a stable structure; (2) Identification of reference landmarks once on the superimposed records for corrected Frankfort Horizontal plane (C-FH) construction and a new semi-automated constructed Sella point to correct Orbital asymmetry; (3) Head orientation of superimposed CBCT images based on the C-FH; (4) Identification of landmarks affected by treatment with the aid of auxiliary reference planes. Evaluation of linear or angular changes derived by projection of same pre- and post-treatment landmarks on the C-FH. Pre- and post-expansion CBCT scans of 20 unilateral cleft lip and palate patients were used to calculate intra and inter-rater reliability. (X, Y and Z) coordinates, mean, standard deviation (SD) and Intra-class Correlation Coefficient (ICC) were calculated.

Results

The proposed coordinates for C-FH construction showed ICC ≥ 0.998 and SD ranging from 0.064 to 0.242 mm. On the other hand, excluded coordinates due to expected natural craniofacial asymmetry had the lowest reliability ICC ≥0.742 and SD dramatically increased up to 1.112 mm.

Conclusion

URM showed adequate reliability so it can be used to produce three-dimensional descriptive data of craniofacial structural changes.

Mandibular canal changes assessed using three-dimensional imaging (CBCT)

INTRODUCTION

To identify changes in the adolescent mandibular canal (MC) using cone-beam computer tomography (CBCT) by locating three-dimensional (3D) anatomical landmarks in the mandible for later growth and treatment applications.

METHODS

Two CBCT images taken 1.5-2 years apart for 50 patients (ages 11-17) were landmarked using AVIZO^®. Six core landmarks were placed relative to the right and left MCs. Three-dimensional coordinates (x, y, z) were obtained. Average distances between paired landmarks were measured using a paired samples t-test. Mean distance differences <1.50mm were determined clinically insignificant and stable. To determine landmark position consistency, repeat CBCTs from 11 patients were landmarked three times one week apart. Coordinates were determined and intra-class correlation coefficient statistics (ICC), mean error difference and confidence intervals were measured.

RESULTS

X and y-coordinates had an internal consistency of 1.00. Z-coordinates had a consistency of 0.995 or higher. Measurement error was <1mm. The largest mean distance change was 2.25mm±3.06mm between the right mandibular foramen and the landmark directly on the right canal, closest to the mesial root of the first molar. The smallest mean distance change was <0.01mm±1.7mm between the right and left mental foramina. Additionally, the bilateral mandibular foramina, bilateral distal and mesial roots of the first molar, and bilateral regions on the MC inferior to both distal and mesial roots of the first molar were stable.

CONCLUSION

All landmarks were determined reliable. The region between the right and left mental foramina was found most stable for this time period in adolescents.

Presurgical Preparation of Infants With Unilateral Cleft Lip and Palate: The SAC-PP-MR Innovative Technique

In this article, we demonstrate an effective, cheap, and fast way to shape the nasal alar cartilage in patients with unilateral cleft lip and palate. This technique straightens the vomer and brings the philtrum, columella, premaxilla, and the maxillary frenum to the midsagittal plane, while the alveolar ridges are shaped and positioned. This reduces the lip and palatal cleft to zero even in a 4-week period.

Dental measurements and Bolton index reliability and accuracy obtained from 2D digital, 3D segmented CBCT, and 3d intraoral laser scanner

Background

To compare the reliability and accuracy of direct and indirect dental measurements derived from two types of 3D virtual models: generated by intraoral laser scanning (ILS) and segmented cone beam computed tomography (CBCT), comparing these with a 2D digital model.

Material and Methods

One hundred patients were selected. All patients’ records included initial plaster models, an intraoral scan and a CBCT. Patients´ dental arches were scanned with the iTero® intraoral scanner while the CBCTs were segmented to create three-dimensional models. To obtain 2D digital models, plaster models were scanned using a conventional 2D scanner. When digital models had been obtained using these three methods, direct dental measurements were measured and indirect measurements were calculated. Differences between methods were assessed by means of paired t-tests and regression models. Intra and inter-observer error were analyzed using Dahlberg´s d and coefficients of variation.

Results

Intraobserver and interobserver error for the ILS model was less than 0.44 mm while for segmented CBCT models, the error was less than 0.97 mm. ILS models provided statistically and clinically acceptable accuracy for all dental measurements, while CBCT models showed a tendency to underestimate measurements in the lower arch, although within the limits of clinical acceptability.

Conclusions

ILS and CBCT segmented models are both reliable and accurate for dental measurements. Integration of ILS with CBCT scans would get dental and skeletal information altogether.

Key words:CBCT, intraoral laser scanner, 2D digital models, 3D models, dental measurements, reliability.

Malocclusion Class II division 1 skeletal and dental relationships measured by cone-beam computed tomography

OBJECTIVES

The purpose of this study was to locate traditionally-used landmarks in two-dimensional (2D) images and newly-suggested ones in three-dimensional (3D) images (cone-beam computer tomographies [CBCTs]) and determine possible relationships between them to categorize patients with Class II-1 malocclusion.

METHODS

CBCTs from 30 patients diagnosed with Class II-1 malocclusion were obtained from the University of Alberta Graduate Orthodontic Program database. The reconstructed images were downloaded and visualized using the software platform AVIZO^®. Forty-two landmarks were chosen and the coordinates were then obtained and analyzed using linear and angular measurements. Ten images were analyzed three times to determine the reliability and measurement error of each landmark using Intra-Class Correlation coefficient (ICC). Descriptive statistics were done using the SPSS statistical package to determine any relationships.

RESULTS

ICC values were excellent for all landmarks in all axes, with the highest measurement error of 2mm in the y-axis for the Gonion Left landmark. Linear and angular measurements were calculated using the coordinates of each landmark. Descriptive statistics showed that the linear and angular measurements used in the 2D images did not correlate well with the 3D images. The lowest standard deviation obtained was 0.6709 for S-GoR/N-Me, with a mean of 0.8016. The highest standard deviation was 20.20704 for ANS-InfraL, with a mean of 41.006.

CONCLUSION

The traditional landmarks used for 2D malocclusion analysis show good reliability when transferred to 3D images. However, they did not reveal specific skeletal or dental patterns when trying to analyze 3D images for malocclusion. Thus, another technique should be considered when classifying 3D CBCT images for Class II-1malocclusion.

Digital evaluation of nasal changes induced by rapid maxillary expansion with different anchorage and appliance design

BACKGROUND

Scientific evidence showed that rapid maxillary expansion (RME) affects naso-maxillary complex, increasing nasal width and volume. This study aimed to evaluate nasal changes induced by rapid maxillary expansion with different anchorage and appliance design by using low dose and cone beam computed tomography.

METHODS

A total of 44 patients (20 males, mean age 8y 8 m ± 1y 2 m; 24 females mean age 8y 2 m ± 1y 4 m) were included in the investigation and divided into three groups according to the appliance: Hyrax-type expander anchored to permanent teeth, modified Hyrax-type expander anchored to deciduous teeth, modified Haas-type expander anchored to deciduous teeth. Maxillary expansion was performed until overcorrection and the expander was passively kept in situ for 7 months at least. All patients had three-dimensional imaging before expansion (T0) and after the retention period (T1). Nasal floor width, nasal wall width, maxillary inter-molar width were measured by means of Mimics software. The paired sample t-test was employed to assess the significance of the differences between the time points; the analysis of variance test (ANOVA) was used to compare differences between groups.

RESULTS

The statistical analysis revealed significant differences between T0 and T1 for each recorded measurement in each group; no significant differences were found by comparing groups.

CONCLUSIONS

Rapid maxillary expansion produces a significant skeletal transverse expansion of nasal region in growing patients. No significant differences in nasal effects are expected when the appliance is anchored onto deciduous teeth, with or without the palatal acrylic coverage.

New algorithm for semiautomatic segmentation of nasal cavity and pharyngeal airway in comparison with manual segmentation using cone-beam computed tomography

INTRODUCTION

Our objectives were to assess reliability, validity, and time efficiency of semiautomatic segmentation using Segura software of the nasal and pharyngeal airways, against manual segmentation with point-based analysis with color mapping.

METHODS

Pharyngeal and nasal airways from 10 cone-beam computed tomography image sets were segmented manually and semiautomatically using Segura (University of Alberta, Edmonton, Alberta, Canada). To test intraexaminer and interexaminer reliabilities, semiautomatic segmentation was repeated 3 times by 1 examiner and then by 3 examiners. In addition to volume and surface area, point-based analysis was completed to assess the reconstructed 3-dimensional models from Segura against manual segmentation. The times of both methods of segmentation were also recorded to assess time efficiency.

RESULTS

The reliability and validity of Segura were excellent (intraclass correlation coefficient, >0.9 for volume and surface area). Part analysis showed small differences between the Segura and manually segmented 3-dimensional models (greatest difference did not exceed 4.3 mm). Time of segmentation using Segura was significantly shorter than that for manual segmentation, 49 ± 11.0 vs 109 ± 9.4 minutes (P <0.001).

CONCLUSIONS

Semiautomatic segmentation of the pharyngeal and nasal airways using Segura was found to be reliable, valid, and time efficient. Part analysis with color mapping was the key to explaining differences in upper airway volume and provides meaningful and clinically relevant analysis of 3-dimensional changes.

Alveolar bone level changes in maxillary expansion treatments assessed through CBCT

OBJECTIVES

Determine changes in alveolar bone levels during expansion treatments as assessed through cone-beam computer tomography (CBCT).

METHODS

Sixty-one patients from Edmonton, Canada, with maxillary transverse deficiencies were split into three groups. One group was treated with a bone-anchored expander, another group was treated with a tooth-borne maxillary expander (Hyrax) and one group was untreated. CBCTs were obtained from each patient at two time points (initialT₁ and at removal of appliance after 6 months T₂). CBCTs were analyzed using AVIZO software and landmarks were placed on different dental and skeletal structures. Intra-examiner reliability for landmarks was done by randomly selecting 10 images and measuring each landmark 3 times, 1 week apart. Descriptive statistics, intraclass correlation coefficients (ICC) and ANOVA analysis were used to determine if there were changes to the alveolar bone levels and if these changes were statistically significant within each group.

RESULTS

Landmarks reliability showed an ICC of at least 0.99 with a 95% confidence interval and a mean measurement error of at least 0.2067mm. Descriptive statistics show that changes in alveolar bone levels were less than 1mm for all three groups and therefore clinically insignificant. Changes between groups were not statistically different (P<0.05) from one another with the exception of 8 distances. However, since the distances were small, they were not considered clinically significant.

CONCLUSION

Alveolar bone level changes were similar in maxillary expansion treatments and in the control group. The effects of maxillary expansion treatments on alveolar bone levels are not clinically significant.

Normal orbit skeletal changes in adolescents as determined through cone-beam computed tomography

Background

To determine three-dimensional spatial orbit skeletal changes in adolescents over a 19 to 24 months observation period assessed through cone-beam computed tomography (CBCT).

Methods

The sample consisted of 50 adolescents aged 11 to 17. All were orthodontic patients who had two CBCTs taken with an interval of 19 to 24 months between images. The CBCTs were analyzed using the third-party software Avizo. Sixteen anatomical landmarks resulting in 24 distances were used to measure spatial structural changes of both orbits. Reliability and measurement error of all landmarks were calculated using ten CBCTs. Descriptive and t-test statistical analyses were used to determine the overall changes in the orbits.

Results

All landmarks showed excellent reliability with the largest measurement error being the Y-coordinate of the left most medial point of the temporalis grooves at 0.95 mm. The mean differences of orbital changes between time 1 and time 2 in the transverse, antero-posterior and vertical directions were 0.97, 0.36 and 0.33 mm respectively. Right to left most antero-inferior superior orbital rim distance had the greatest overall transverse change of 4.37 mm. Right most posterior point of lacrimal crest to right most postero-lateral point of the superior orbital fissure had the greatest overall antero-posterior change of 0.52 mm. Lastly, left most antero-inferior superior orbital rim to left most antero-superior inferior orbital rim had the greatest overall vertical change of 0.63 mm.

Conclusions

The orbit skeletal changes in a period of 19–24 months in a sample of 11–17 year olds were statistically significant, but are not considered to be clinically significant. The overall average changes of orbit measurements were less than 1 mm.

Sphenoid bone changes in rapid maxillary expansion assessed with cone-beam computed tomography

OBJECTIVE

Rapid maxillary expansion (RME) is used to expand the maxilla and increase arch perimeter; yet, there are few reports on its effects on the sphenoid bone. With cone-beam computed topography (CBCT), it is possible to visualize sphenoid bone changes. The purpose of this study was to investigate sphenoid bone changes observed in conjunction with RME treatments, using CBCT.

METHODS

Sixty patients (34 women and 26 men, aged 11-17 years) underwent RME as part of their orthodontic treatment. Patients were randomly assigned to one of three groups: a tooth-anchored group, a bone-anchored group, or a control group. Initial CBCT scans were performed preceding the RME treatment (T1) and again directly after the completion of expansion (T2). Statistical analysis included ANOVA, descriptive statistics, and the intraclass correlation coefficient (ICC).

RESULTS

The reliability of the landmark location was at least 0.783, and the largest ICC mean measurement error was 2.32 mm. With regard to distances, the largest change was 0.78 mm, which was not statistically significant (p > 0.05). Statistical significance was established in patient groups of the same sex and treatment type for the following distance measurements: right anterior lateral pterygoid plate to the right edge of the hypophyseal fossa (d2), anterior distance between the medial pterygoid plates (d4), and anterior distance between the left medial and lateral plates (d8).

CONCLUSIONS

In this study, there were no clinically significant changes in the sphenoid bone due to RME treatments regardless of sex or treatment type.

Skeletal and dental effects of rapid maxillary expansion assessed through three-dimensional imaging: A multicenter study

OBJECTIVES

The aim of this study was to determine the skeletal and dental changes in rapid maxillary expansion treatments in two different populations assessed through cone-beam computer tomography (CBCT).

MATERIALS AND METHODS

Twenty-one patients from Edmonton, Canada and 16 patients from Cairo, Egypt with maxillary transverse deficiency (11-17 years old) were treated with a tooth-borne maxillary expander (Hyrax). CBCTs were obtained from each patient at two time points (initial T1 and at removal of appliance at 3-6 months T2). CBCTs were analyzed using AVIZO software and landmarks were placed on skeletal and dental anatomical structures on the cranial base, maxilla and mandible. Descriptive statistics, intraclass correlation coefficients and one-way ANOVA analysis were used to determine if there were skeletal and dental changes and if these changes were statistically different between both populations.

RESULTS

Descriptive statistics show that dental changes were larger than skeletal changes for both populations. Skeletal and dental changes between populations were not statistically different (P<0.05) from each other with the exception of the upper incisor proclination being larger in the Indiana group (P>0.05).

CONCLUSION

Rapid maxillary expansion treatments in different populations demonstrate similar skeletal and dental changes. These changes are greater on the dental structures compared to the skeletal ones in a 4:1 ratio.

Cranial base growth in adolescence assessed through cone-beam computerized tomographies--pilot study

OBJECTIVE

To assess growth of the middle/posterior cranial base during adolescence based on landmarks located on serial three-dimensional cone-beam computerized tomography (CBCT) images.

MATERIALS AND METHODS

CBCT scans from 62 adolescents (11 to 17 years) at baseline and 12 months were used. Eleven landmarks in the cranial base were identified. Linear landmark distances were compared over the two time points using basic descriptive statistics. Shape analysis was carried out using R (R Foundation for Statistical Computing, Austria). Discrete curves were obtained and aligned via a Procrustes transformation and examined for group dimorphism and longitudinal change.

RESULTS

Mean differences between linear distances in the cranial base were within 1mm, apart from the difference between the right and left auditory external meatuses, which was 2.25 mm. No statistically significant longitudinal differences in shape were found in relation to the peak growth period.

CONCLUSION

Cranial base growth was minimal over the observation period. There were no differences in terms of the amount and pattern of growth. The cranial base is said to complete most of its growth by age 12, but this has only been verified through two-dimensional studies. Our findings using CBCT confirm this, and support the use of the cranial base as a stable anatomical reference structure for superimpositioning.

Reliability of anatomic structures as landmarks in three-dimensional cephalometric analysis using CBCT

OBJECTIVE

To identify anatomic structures in three dimensions and examine their reliability to be used as landmarks in a three-dimensional coordinate cephalometric analysis, using cone-beam computerized tomography (CBCT).

MATERIALS AND METHODS

Thirty CBCT images were randomly selected for landmark location. Forty-two anatomic landmarks, which are not included in the traditional cephalometric landmarks, were chosen based on radiographic characteristics that make them pragmatic to mark in the CBCT image slices. The principal investigator marked the full set of landmarks on the software by navigating in the X, Y, and Z axes for every image three times, with each measurement trial being at least 1 week apart. One other investigator also located the landmarks once for each image for reliability purposes. Intraclass correlation coefficients (ICCs) were used to analyze the mean differences in landmark location in all axes.

RESULTS

Intra- and interexaminer reliability for x, y, and z coordinates for all landmarks had ICC greater than 0.95 with confidence interval of 0.88-0.99. Mean measurement differences found were <1.4 mm for all landmarks in all three coordinates. Mean measurement error differences obtained in the principal investigator's trials were primarily <0.5 mm.

CONCLUSION

The most reliable and reproducible landmarks tested for use in CBCT are mental foramina, infraorbital foramina, inferior hamulus, dens axis, foramina transversarium of atlas, medial and lateral condyles of the mandible, superior clinoid processes, and mid-clinoid.

Orthodontic bonding to porcelain: a systematic review

OBJECTIVE

To use a systematic review to determine which materials and technique/protocol present the highest success rate in bonding brackets to porcelain surfaces.

MATERIALS AND METHODS

Different databases were searched without limitations up to July 2013. Additionally, the bibliographies of the finally selected articles were hand searched to identify any relevant publications that were not identified earlier. In vitro and in vivo articles were included.

RESULTS

No in vivo articles were found that fulfilled the inclusion criteria. A total of 45 in vitro articles met all inclusion criteria. They were published between 2000 to July 2013.

CONCLUSIONS

The best protocol described in this review is the etching of 9.6% hydrofluoric acid for 1 minute, rinsed for 30 seconds, and then air-dried. The etching of hydrofluoric acid should be followed by an application of silane. Considering the harmful effects of etching with hydrofluoric acid, another appropriate suggestion is mechanical roughening with sandblasting followed by an application of silane.

Correlation between three-dimensional morphological changes of the hyoid bone with other skeletal maturation methods in adolescents

OBJECTIVE

The study compares growth changes of hyoid bone in cone-beam computed tomography (CBCT) with conventional skeletal maturation methods to examine their potential implications in the development of a three-dimensional method.

STUDY DESIGN

Subjects (n = 62, 11-17 years of age) were exposed to CBCT at a six-month interval (T1/T2/T3). Ten-hyoid distances were compared with age, hand wrist skeletal maturation index (SMI), and cervical vertebral maturation stage (CS).

RESULTS

The length of greater cornua (GC) was most frequently, moderate to highly correlated with age (right: 0.57/0.53/0.58; left: 0.45/0.50/0.48), SMI (right: 0.52/0.40/0.45; left: 0.42 at T3), and CS (right: 0.52 at T1), followed by the length of the hyoid bone with age (right: 0.50/0.49/0.47; left: 0.44/0.47 at T1/T2), SMI (right: 0.45/0.41 at T1/T2), and CS (right: 0.48 at T1). The width of body of the hyoid (HB) width was correlated with age (0.43/0.44/0.44). The GC-HB gap was correlated with age (right: -0.41 at T3) and SMI (right: -0.42 at T1).

CONCLUSION

Peripubertal hyoid maturation did not yield sufficient diagnostic information for considerations in the development of a 3D-skeletal maturation method.

Accuracy of laser-scanned models compared to plaster models and cone-beam computed tomography

OBJECTIVE

To compare the accuracy of measurements obtained from the three-dimensional (3D) laser scans to those taken from the cone-beam computed tomography (CBCT) scans and those obtained from plaster models.

MATERIALS AND METHODS

Eighteen different measurements, encompassing mesiodistal width of teeth and both maxillary and mandibular arch length and width, were selected using various landmarks. CBCT scans and plaster models were prepared from 60 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner, and the selected landmarks were measured using its software. CBCT scans were imported and analyzed using the Avizo software, and the 26 landmarks corresponding to the selected measurements were located and recorded. The plaster models were also measured using a digital caliper. Descriptive statistics and intraclass correlation coefficient (ICC) were used to analyze the data.

RESULTS

The ICC result showed that the values obtained by the three different methods were highly correlated in all measurements, all having correlations>0.808. When checking the differences between values and methods, the largest mean difference found was 0.59 mm±0.38 mm.

CONCLUSIONS

In conclusion, plaster models, CBCT models, and laser-scanned models are three different diagnostic records, each with its own advantages and disadvantages. The present results showed that the laser-scanned models are highly accurate to plaster models and CBCT scans. This gives general clinicians an alternative to take into consideration the advantages of laser-scanned models over plaster models and CBCT reconstructions.

Towards a viscoelastic model for the unfused midpalatal suture: development and validation using the midsagittal suture in New Zealand white rabbits

Maxillary expansion treatment is a commonly used procedure by orthodontists to widen a patient's upper jaw. As this is typically performed in adolescent patients, the midpalatal suture, connective tissue adjoining the two maxilla halves, remains unfused. Studies that have investigated patient response to expansion treatment, generally through finite element analysis, have considered this suture to behave in a linear elastic manner or it was left vacant. The purpose of the study presented here was to develop a model that could represent the midpalatal suture's viscoelastic behavior. Quasilinear viscoelastic, modified superposition, Schapery's, and Burgers modeling approaches were all considered. Raw data from a previously published study using New Zealand White Rabbits was utilized for model parameter estimation and validation. In this study, Sentalloy(®) coil springs at load levels of 0.49N (50g), 0.98N (100g), and 1.96N (200g) were used to widen the midsagittal suture of live rabbits over a period of 6 weeks. Evaluation was based on a models ability to represent experimental data well over all three load sets. Ideally, a single set of model constants could be used to represent data over all loads tested. Upon completion of the analysis it was found that the modified superposition method was able to replicate experimental data within one standard deviation of the means using a single set of constants for all loads. Future work should focus on model improvement as well as prediction of treatment outcomes.

Multiobjective optimization framework for landmark measurement error correction in three-dimensional cephalometric tomography

The purpose of this study is to minimize errors that occur when using a four vs six landmark superimpositioning method in the cranial base to define the co-ordinate system. Cone beam CT volumetric data from ten patients were used for this study. Co-ordinate system transformations were performed. A co-ordinate system was constructed using two planes defined by four anatomical landmarks located by an orthodontist. A second co-ordinate system was constructed using four anatomical landmarks that are corrected using a numerical optimization algorithm for any landmark location operator error using information from six landmarks. The optimization algorithm minimizes the relative distance and angle between the known fixed points in the two images to find the correction. Measurement errors and co-ordinates in all axes were obtained for each co-ordinate system. Significant improvement is observed after using the landmark correction algorithm to position the final co-ordinate system. The errors found in a previous study are significantly reduced. Errors found were between 1 mm and 2 mm. When analysing real patient data, it was found that the 6-point correction algorithm reduced errors between images and increased intrapoint reliability. A novel method of optimizing the overlay of three-dimensional images using a 6-point correction algorithm was introduced and examined. This method demonstrated greater reliability and reproducibility than the previous 4-point correction algorithm.

Transverse dental changes after tooth-borne and bone-borne maxillary expansion

OBJECTIVE

Determine the differences in skeletal and dental maxillary expansion as evidenced by the degree of dental tipping and if this is symmetrical or not.

METHODS

Sixty-two patients who were diagnosed as requiring maxillary expansion treatment were recruited over an 18-month period. Patients were randomly allocated into three groups where a total of three to four cone-beam computerized tomographies (CBCT) were obtained throughout a one-year period depending on the group allocated. Landmarks used were from the first and second molars and premolars of the maxilla. For each of the eight teeth, three landmarks were identified: the root apex, alveolar bone and pulp chamber. Statistical analysis consisted in the use of MANOVA and after significant overall effects were detected, the univariate repeated measures results were analyzed along with separate ANOVA for each variable at each of the four time points.

RESULTS

There was strong overall significance for time, group, and time*group. The first and second molars saw both bone- and tooth-anchored treatment groups with significantly different dental inclination than the control group. For the second premolars, only the tooth-anchored group was significantly different from control. The tooth-anchored group was also significantly different than the control group in the first premolar measurements. For the analysis of asymmetry in dental inclination, no significant time, group, or time*group effects were seen overall.

CONCLUSION

The analysis provided evidence that dental tipping does occur in the molars for both RME treatments, while the premolars showed increased tipping in the tooth-anchored, but not the bone-anchored group.

Assessment of skeletal maturation based on cervical vertebrae in CBCT

Diagnosis of skeletal age in adolescents helps orthodontists select and time treatments. Currently this is done using lateral cephalometric radiographs. This study evaluates the application of the conventional method in cone-beam computer tomographic (CBCT) images to bring forth assessment of skeletal maturation in three-dimensions. Ninety-eight lateral cephalometric radiographs and CBCT scans were collected from orthodontic patients between 11 to 17 years of age over an 18-month period. CBCT scans were examined in seven sagittal slices based on cervical vertebral maturation staging (CVMS). Collected CVMS values were compared with those from corresponding lateral cephalometric radiograph. CVMS measured from CBCT and lateral cephalometric radiographs were the same on average. However, they were not consistent with each other and scored interclass correlation coefficient of 0.155 in validity test. Interoperator reliability was weak (0.581). Adaptation of cervical vertebrae maturation staging in CBCT requires further clarifications or modifications to become consistent with lateral cephalometric examinations and to become a reliable method. Alternatively, a completely new method may be developed consisting of maturational indicators or landmarks unique to CBCT imaging.

Interrelationship and limitations of conventional radiographic assessments of skeletal maturation

Assessments of skeletal maturation (ASM) are used by clinicians to optimize treatments for each patient. This study examines the interrelationship between and limitations of hand-wrist and cervical vertebrae maturation methods in adolescent patients. Radiographs (hand-wrist and lateral cephalometric) were obtained from patients (n=62, 11 to 17 years of age) at two-time periods (T1/T2) with time intervals of 9.75 to 16.50 months. Radiographs were scored using cervical vertebral maturation staging (CS) and Fishman's skeletal maturation indices (SMI). Functional data analysis was used to visually assess maturational changes of the cervical vertebrae. Both SMI and CS increased over the period of observation. Age was moderately correlated with SMI (0.707/0.651 at T1/T2) and mildly correlated with CS (0.431/0.314 at T1/T2). There was some evidence of gender variability in SMI. The correlations between SMI and CS were 0.513 and 0.372 at T1 and T2, respectively. Functional data analysis illustrated the difficulty in differentiating contiguous cervical stages. Discrepancies exist between both scoring methods. Further studies are needed to overcome the difficulties encountered with CS. Clinicians are advised to use ASM methods with caution in adolescent patients given the aforementioned discrepancies. Separate references for boys and girls are not required.

New statistical method to analyze three-dimensional landmark configurations obtained with cone-beam CT: basic features and clinical application for rapid maxillary expansion

Objective

To describe a statistical method of three-dimensional landmark configuration data and apply it to an orthodontic data set comparing two types of rapid maxillary expansion (RME) treatments.

Materials and Methods

Landmark configurations obtained from cone beam CT scans were used to represent patients in two types (please describe what were two types) of RME groups and a control group over four time points. A method using tools from persistent homology and dimensionality reduction is presented and used to identify variability between the subjects.

Results

The analysis was in agreement with previous results using conventional methods, which found significant differences between treatment groups and the control, but no distinction between the types of treatment. Additionally, it was found that second molar eruption varied considerably between the subjects, and this has not been evaluated in previous analyses.

Conclusion

This method of analysis allows entire configurations to be considered as a whole, and does not require specific inter-landmark distances or angles to be selected. Sources of variability present themselves, without having to be individually sought after. This method is suggested as an additional tool for the analysis of landmark configuration data.

Cranial base foramen location accuracy and reliability in cone-beam computerized tomography

INTRODUCTION

The purpose of this study was to evaluate the reliability and accuracy in locating several different foramina in the cranial base by using cone-beam computerized tomography (CBCT) images for future use in establishing reference coordinate systems.

METHODS

CBCT images from 10 dry skulls were taken with and without the foramina ovale, spinosum, and rotundum, and the hypoglossal canals filled with radiopaque gutta-percha (gold standard). Three evaluators identified the foramen landmarks in the CBCT images without gutta-percha. Mean differences and main researcher intraexaminer and interexaminer reliability were measured by using intraclass correlation coefficients for all landmark coordinates. Descriptive statistics were calculated with respect to the landmark coordinates and distances to the reference points.

RESULTS

Intraexaminer and interexaminer reliability values for the x-, y-, and z-coordinates for all landmarks were greater than 0.9 with the exception of 4 (of 72) points that still had acceptable interexaminer reliability (>0.75). Mean measurement error differences obtained in the principal investigator's trials were primarily less than 0.5 mm. When comparing the mean distance differences of the same examiner and between the 3 examiners with the gold standard, the highest difference obtained was 1.3 mm.

CONCLUSIONS

Foramina spinosum, ovale, and rotundum, and the hypoglossal canal all provided high intraexaminer reliability and accuracy, and can be considered acceptable landmarks to use in establishing reference coordinate systems for future 3-dimensional superimposition analysis.

Reproducibility, reliability and validity of measurements obtained from Cecile3 digital models

The aim of this study was to determine the reproducibility, reliability and validity of measurements in digital models compared to plaster models. Fifteen pairs of plaster models were obtained from orthodontic patients with permanent dentition before treatment. These were digitized to be evaluated with the program Cécile3 v2.554.2 beta. Two examiners measured three times the mesiodistal width of all the teeth present, intercanine, interpremolar and intermolar distances, overjet and overbite. The plaster models were measured using a digital vernier. The t-Student test for paired samples and interclass correlation coefficient (ICC) were used for statistical analysis. The ICC of the digital models were 0.84 +/- 0.15 (intra-examiner) and 0.80 +/- 0.19 (inter-examiner). The average mean difference of the digital models was 0.23 +/- 0.14 and 0.24 +/- 0.11 for each examiner, respectively. When the two types of measurements were compared, the values obtained from the digital models were lower than those obtained from the plaster models (p < 0.05), although the differences were considered clinically insignificant (differences < 0.1 mm). The Cécile digital models are a clinically acceptable alternative for use in Orthodontics.

Sensitivity analysis for plane orientation in three-dimensional cephalometric analysis based on superimposition of serial cone beam computed tomography images

OBJECTIVES

The purpose of this study was to evaluate the potential errors associated with superimposition of serial cone beam CT (CBCT) images utilizing reference planes based on cranial base landmarks using a sensitivity analysis.

METHODS

CBCT images from 62 patients participating in a maxillary expansion clinical trial were analysed. The left and right auditory external meatus (AEM), dorsum foramen magnum (DFM) and the midpoint between the left and right foramen spinosum (ELSA) were used to define a three-dimensional (3D) anatomical reference co-ordinate system. Intraclass correlation coefficients for all four landmarks were obtained. Transformation of the reference system was carried out using the four landmarks and mathematical comparison of values.

RESULTS

Excellent intrareliability values for each dimension were obtained for each landmark. Evaluation of the method to transform the co-ordinate system was first done by comparing interlandmark distances before and after transformations, giving errors in lengths in the order of 10-14% (software rounding error). A sensitivity evaluation was performed by adding 0.25 mm, 0.5 mm and 1 mm error in one axis of the ELSA. A positioning error of 0.25 mm in the ELSA can produce up to 1.0 mm error in other cranial base landmark co-ordinates. These errors could be magnified to distant landmarks where in some cases menton and infraorbital landmarks were displaced 4-6 mm.

CONCLUSIONS

Minor variations in location of the ELSA, both the AEM and the DFM landmarks produce large and potentially clinically significant uncertainty in co-ordinate system alignment.