Positional, morphologic, and volumetric differences in TMJ in unilateral posterior crossbites and controls: A retrospective CBCT study.

OBJECTIVES: The objective of this study was to evaluate if there are any morphologic, positional, and volumetric differences in the temporomandibular joint (TMJ) of patients with unilateral posterior crossbite (UPC) compared to controls. Another objective was to analyse the discrepancy in the TMJ between the crossbite versus non-crossbite side in UPC versus right and left sides in controls. Additionally, this study aimed to evaluate the differences in the bone density at the masseteric insertion site at the angle of mandible in the UPC group and control group. MATERIAL AND METHODS: One hundred and thirty-two CBCTs were analysed with 66 patients in UPC group and 66 patients in control group (non-crossbite). Temporomandibular joint spaces - Anterior joint space (AJS), Superior joint space (SJS), Posterior joint space (PJS), Medial joint space (MJS), Middle joint space (MiJS), and Lateral joint space (LJS) were measured. Additionally, bone density at angle of mandible and volume of mandibular condyle were evaluated. The measurements were compared between the groups as well as between the crossbite and non-crossbite sides within the UPC group and between right and left sides within the control group. Furthermore, the associations between UPC and changes in TMJ regarding joint space availability, bone density, condylar head volume, and the effects of sex and age were evaluated using regression analysis. RESULTS: It was observed that UPC group showed a greater condylar volume, than the control group. Additionally, a larger mean discrepancy was observed between the crossbite side and non-crossbite side within the UPC group concerning condylar volume than controls. Concerning age, condylar volume was observed to be larger in adults than children. Adults showed significantly greater bone density and condylar volume than adolescents. Concerning sex, it was observed that males showed a larger SJS (right), MiJS, LJS, and bone density at the mandibular angle than females. CONCLUSION: There is a difference in the TMJ parameters particularly condylar volume in patients with UPC compared to controls.

Biomechanics of conventional and miniscrew-assisted rapid palatal expansion.

Posterior Crossbite is a common condition resulting because of transverse maxillary deficiency. The growth of the craniofacial complex finishes first in the transverse dimension, followed by sagittal and vertical dimensions. Conventional rapid palatal expansion (RPE) appliances are commonly used to correct transverse maxillary deficiency. Although RPE is efficient in correcting posterior crossbite, it results in dental side effects such as buccal tipping of maxillary molars, root resorption, bone dehiscence, and relapse. Mini-implant-assisted RPE has been introduced to increase the skeletal effects of expansion especially in patients with increased maturation and greater interdigitation of midpalatal suture. This article will review the biomechanics of RPE and mini-implant-assisted RPE. Additionally, the different designs of MARPE and the long-term clinical effects of expansion appliances will also be discussed in detail.

Long-term evaluation of soft-tissue changes after miniscrew-assisted and conventional rapid palatal expansion using voxel-based superimposition of cone-beam computed tomography scans.

INTRODUCTION: This study aimed to evaluate the soft-tissue changes in the long-term after miniscrew-assisted rapid palatal expansion (MARPE) and conventional rapid palatal expansion (RPE) appliances compared with a matched control group using voxel-based superimposition of cone-beam computed tomography (CBCT) scans. METHODS: A total of 180 CBCTs for 60 patients at 3-time points were evaluated: pretreatment (T1), postexpansion (T2), and posttreatment (T3) for 3 groups: (1) MARPE, (2) RPE, and (3) controls (time-period T1 to T3: MARPE, 2 years 8 months; RPE, 2 years 9 months; control, 2 years 7 months). The voxel-based superimposition technique was used to superimpose the CBCT scans, after which the soft-tissue surfaces were extracted from the superimposed T1-CBCT, T2-CBCT, and T3-CBCT scans. Nine landmarks were identified on the CBCT scans: nasion, A-point, pogonion, right and left alar base, right and left zygoma, and right and left gonion. The coordinates of the 9 parameters were obtained in the x-axis, y-axis, and z-axis for the CBCT scans and subjected to statistical analyses. The changes in the soft-tissue surfaces were also evaluated by color-coded maps for short-term (T2) and long-term (T3) changes. The mean changes from T1 to T2 and T1 to T3 were tested against no change within the groups by paired t test, and the mean changes among the 3 groups were compared with analysis of variance F test with Tukey's Honest significant difference used for adjusting P values for multiple testing. RESULTS: In the short term, both MARPE and RPE led to a significant downward movement of pogonion, left gonion, and lateral movement of the right and left alar base compared with controls at T2 (P <0.05). In addition, MARPE led to a significant downward movement of right gonion than controls at T2 (P <0.05). Moreover, RPE led to a significant downward and forward movement of A-point and downward movement of the right and left alar base than controls at T2 (P <0.05). However, in the long-term, there were no significant differences in the soft-tissue changes among the MARPE, RPE, and control groups. CONCLUSIONS: MARPE and RPE do not lead to significant soft-tissue changes in the long term when compared with controls.

Stereotypical nationality representations in HRI: perspectives from international young adults.

People often form immediate expectations about other people, or groups of people, based on visual appearance and characteristics of their voice and speech. These stereotypes, often inaccurate or overgeneralized, may translate to robots that carry human-like qualities. This study aims to explore if nationality-based preconceptions regarding appearance and accents can be found in people's perception of a virtual and a physical social robot. In an online survey with 80 subjects evaluating different first-language-influenced accents of English and nationality-influenced human-like faces for a virtual robot, we find that accents, in particular, lead to preconceptions on perceived competence and likeability that correspond to previous findings in social science research. In a physical interaction study with 74 participants, we then studied if the perception of competence and likeability is similar after interacting with a robot portraying one of four different nationality representations from the online survey. We find that preconceptions on national stereotypes that appeared in the online survey vanish or are overshadowed by factors related to general interaction quality. We do, however, find some effects of the robot's stereotypical alignment with the subject group, with Swedish subjects (the majority group in this study) rating the Swedish-accented robot as less competent than the international group, but, on the other hand, recalling more facts from the Swedish robot's presentation than the international group does. In an extension in which the physical robot was replaced by a virtual robot interacting in the same scenario online, we further found the same results that preconceptions are of less importance after actual interactions, hence demonstrating that the differences in the ratings of the robot between the online survey and the interaction is not due to the interaction medium. We hence conclude that attitudes towards stereotypical national representations in HRI have a weak effect, at least for the user group included in this study (primarily educated young students in an international setting).

Skeletal and Dentoalveolar Changes With Mandibular Expansion in Growing Children.

Introduction The primary objective of this study was to quantitatively analyze the skeletal and dentoalveolar parameters following the mandibular expansion with a banded appliance. It was also part of the study to evaluate the amount of dental expansion and assess the change in the intermolar and individual first molar angulation. The basal bone parameters were compared to assess the skeletal effect of removable mandibular expansion appliance therapy. Methods In this retrospective cone beam computed tomography (CBCT) study, a total of 80 subjects with mandibular expansion therapy were screened. After imposing inclusion/exclusion criteria, 70 patients (40 females and 30 males) with a mean age of 8.8±1.24 years and 4.79±3.59 months were included. The mean expansion period was 3.04±1.61 months. Skeletal parameters such as buccal cortical thickness, buccal bone width, and cortical density were measured at 2mm from the alveolar crest, mid-root, and apex region in the coronal slice at the level of the mesiobuccal root of the first molar. Expansion parameters such as intermolar width, intermolar angulation, and individual molar angulation were also measured in the same slice. Finally, basal bone parameters such as inter-mental foramina distance and anterior arch perimeter were recorded. Results No significant difference (p>0.05) was found for most skeletal parameters following the expansion, except for the mid-root buccal bone width (p<0.05). On average, 4.54±2.53 mm of dental expansion (p<0.05) was achieved at the first molar region. Individual molar angulation showed a statistically significant difference (right = 7.46±7.91°, left = 7.53±7.18°, p=<0.05). The basal bone parameters showed no significant difference (p>0.05). Conclusions The mandibular expansion device leads to an increase in intermolar distance. The amount of expansion achieved with such devices is due to the buccal tipping of the molars. Skeletal effects such as cortical thickness, buccal bone width, or changes in the basal bone dimensions should not be expected with mandibular expansion therapy.

Prevalence and Clinical Significance of Incidental Findings in the Maxillofacial Complex of Adolescent Orthodontic Patients: A Retrospective Cone Beam Computed Tomography Analysis.

OBJECTIVES: The aim of this study was to determine the prevalence and severity of incidental findings in the maxillofacial complex of orthodontic patients imaged with cone beam computed tomography (CBCT) and assign those findings an appropriate clinical significance. METHODOLOGY: Incidental findings (IF) were identified in 250 CBCT scans of adolescent orthodontic patients (aged 13-18 years) with a large field-of-view and categorized based on their anatomic location and placed into one of six subgroups based on anatomic region: i) sino-nasal, ii) dentoalveolar, iii) nasooropharyngeal airway, iv) temporomandibular joint, v) neck, vi) calcifications, and vi) miscellaneous findings. Additionally, findings were assigned a clinical significance score based on severity on a scale of mild, moderate and severe. Mild IF was defined as an IF that does not require any further investigation or referral. Moderate IF was defined as an IF that has the tendency to become clinically significant and should be observed periodically. IFs that warrant further investigation and/or intervention were designated as severe. RESULTS: The percentage of IFs in sino-nasal and dento-alveolar regions were 44.7% and 19.1% respectively. The percentage of IFs with mild, moderate, and severe clinical significance were 27%, 72%, and 1%, respectively. Out of the IFs involving calcifications, 80.8% were stylohyoid calcifications and <1% were cranial cavity IFs such as petroclinoid calcifications and falx cerebri calcifications. Among the sino-nasal findings, 1.2% were identified as severe. CONCLUSION: The sino-nasal region had the highest frequency of IFs. Understanding the prevalence of incidental findings and its clinical relevance is important for clinicians to allow for appropriate monitoring and timely treatment of patients.

Assessment of clear aligner accuracy of 2 clear aligners systems.

INTRODUCTION: This study compared treatment efficacy for specific tooth movements between 2 clear aligner systems (Clarity [3M Oral Care Solutions, St Paul, Minn] and Invisalign [Align Technology, San Jose, Calif]). METHODS: The study sample included 47 patients (7 males, 40 females; mean age, 36.57 ± 15.97 years) treated with Invisalign and 37 (4 males, 33 females; mean age, 34.30 ± 16.35 years) treated with Clarity aligners who completed their first set of aligners and had an initial refinement scan. Initial and predicted models were obtained from the initial simulated treatment plan. The first model of the refinement scan was labeled as achieved. SlicerCMF software (version 3.1; http://www.slicer.org) was used to superimpose the achieved and predicted digital models over the initial ones with regional superimposition on the relatively stable first molars. Nine hundred forty teeth in the Invisalign system were measured for horizontal, vertical, and angular movements and transverse width and compared with similar measurements of 740 teeth for the Clarity aligners. The deviation from the predicted was calculated and compared between both systems. RESULTS: The deviation achieved from the predicted was significant between the groups for the mandibular interpremolar and intercanine widths (P <0.05). Clarity aligners significantly undercorrected rotations compared with Invisalign for the mandibular first premolars, mandibular canines, maxillary canines, and maxillary central incisors. There was no statistically significant difference between the groups for the achieved vs predicted movements in the horizontal and vertical planes (P >0.05). CONCLUSIONS: The efficacy of clear aligner therapy systems (Clarity and Invisalign) in treating mild and moderate malocclusions was comparable. Deviation of the achieved movements from the predicted was greatest for rotational and vertical movements.

Dynamic changes in transcriptome during orthodontic tooth movement.

OBJECTIVES: The objective of this study was to determine global changes in gene expression with next generation sequencing (NGS) in order to assess the biological effects of orthodontic tooth movement (OTM) on alveolar bone in a rat model. MATERIALS AND METHODS: Thirty-five Wistar rats (age 14 weeks) were used in the study. The OTM was performed using closed coil Nickel-Titanium spring to apply a mesial force on maxillary first molars of 8-10 g. Three hours, 1, 3, 7 and 14 days after the placement of the appliance, rats were killed at each time point respectively. The alveolar bone, around left maxillary first molar, were excised on compression side. The samples were immediately frozen in liquid nitrogen for subsequent RNA extraction. Total RNA samples were prepared for mRNA sequencing using the Illumina kit. RNA-Seq reads were aligned to the rat genomes using the STAR Aligner and bioinformatic analysis was performed. RESULTS: A total of 18 192 genes were determined. Day 1 has the highest number of differentially expressed genes (DEGs) observed with more upregulated than downregulated genes. A total of 2719 DEGs were identified to use as input for the algorithm. Six distinct clusters of temporal patterns were observed representing proteins that were differentially regulated indicating different expression kinetics. Principal component analysis (PCA) showed distinct clustering by time points and days 3, 7 and 14 share similar gene expression pattern. CONCLUSIONS: Distinct gene expression pattern was observed at different time points studied. Hypoxia, inflammation and bone remodelling pathways are major mechanisms behind OTM.

Short-term and long-term effects of miniscrew-assisted and conventional rapid palatal expansion on the cranial and circummaxillary sutures.

INTRODUCTION: The objective of this study was to analyze the short-term and long-term effects of miniscrew-assisted rapid palatal expansion (MARPE) and conventional rapid palatal expansion (RPE) appliances on cranial and circummaxillary sutures as compared with a matched control group. METHODS: One hundred and eighty cone-beam computed tomography scans for 60 subjects were evaluated for the 3 groups: (1) MARPE (n = 20; aged 13.7 ± 1.74 years), (2) RPE (n = 21; age 13.9 ± 1.14 years), and (3) control (n = 19; age 13.3 ± 1.49 years) at pretreatment (T1), postexpansion (T2), and posttreatment (T3) (T1 to T3: MARPE, 2 years 8 months; RPE, 2 years 9 months; control, 2 years 7 months). Frontonasal suture, frontomaxillary suture, zygomaticomaxillary suture, zygomaticofrontal suture, intermaxillary suture, pterygomaxillary suture, nasomaxillary suture, and zygomaticotemporal suture were measured on the right and left sides for all 3 time labels. In addition, midpalatal suture was measured at the incisor, canine, and molar levels. RESULTS: Within-group analysis showed that MARPE and RPE led to a significant increase in the widths of frontonasal, frontomaxillary, intermaxillary, nasomaxillary, and midpalatal suture at incisor, canine, and molar levels at T2 compared with T1. Between-group analysis showed that MARPE and RPE significantly increased the width of the intermaxillary and midpalatal suture at the incisor, canine, and molar compared with controls at T2. In the long term, between-group comparisons showed no significant difference among the 3 groups except that MARPE led to a significant increase in the width of midpalatal suture at incisor, canine, and molar levels compared with RPE and controls at T3. CONCLUSIONS: MARPE led to a significant increase in the width of the midpalatal suture at incisor, canine, and molar levels compared with RPE and controls in the long term. There was no difference in the width of other cranial and circummaxillary sutures among the 3 groups in the long term.

How does alendronate affect orthodontic tooth movement in osteogenesis imperfecta: an in vivo study on a mice model.

OBJECTIVES: The purpose of this study was to evaluate the effects of alendronate on orthodontic tooth movement (OTM) and bone modelling/remodelling in an osteogenesis imperfecta (OI) mice model. MATERIALS AND METHODS: Ten-week-old male and female OI mice (Col1a2oim, n = 32) were divided into four groups: 1. Alendronate male (AM, n = 8), 2. Alendronate female (AF, n = 8), 3. saline male (SM, n = 8), and 4. saline female (SF, n = 8). The mice in all four groups received either Alendronate (0.05 mg/kg) or vehicle (saline 0.05 mg/kg) subcutaneously for 2 weeks prior to the placement of orthodontic spring. A nickel-titanium spring applying 3-5 cN of force was used to perform the OTM for 1 week. After 7 days of OTM, the OI mice were euthanized with CO2 inhalation and microfocus computed tomography and histological analyses were performed. RESULTS: AM and AF mice showed a significant decrease (P < 0.05) in the rate of OTM compared with SM and SF mice, respectively. In addition, AM and AF mice showed a significant increase (P < 0.05) in the bone volume fraction (BVF) and tissue density (TD) compared with SM and SF mice. Histological analysis of haematoxylin-eosin staining revealed a hyalinization zone in AM and AF mice compared with SM and SF mice. Furthermore, tartrate-resistant acid phosphatase staining indicated decreased number of osteoclasts in AM and AF mice compared with SM and SF mice. Picrosirius red staining showed, Alendronate treatment led to thick uniform and smooth morphology of collagen fibres as compared with saline group. Similarly, second harmony generation images also revealed thicker collagen fibres at the periodontal ligament (PDL)-cementum entheses and PDL-alveolar bone entheses in AM and AF mice compared with SM and SF mice. CONCLUSIONS: Alendronate led to a decrease in the rate of OTM, increase in BVF and TD, decrease in the number of osteoclasts, and smooth and thick collagen fibres compared with saline in both male and female OI mice.

Estimating the 3-D location of impacted maxillary canines: A CBCT-based analysis of severity of impaction.

OBJECTIVES: The objective of the study was to quantify the 3-D location of impacted canines by measuring their linear and angular deviations in relation to adjacent structures and further evaluate impaction severity. METHODS: CBCT images of 314 impacted canines were analysed in the sagittal, coronal and axial planes. Linear and angular measurements were recorded. Canine inclination was identified in coronal and sagittal planes. An evaluation system was constructed for analysis. Upright canine was considered as the appropriate position for fully erupted maxillary canine. Outcomes were compared between right and left sides and by gender. For categorical variables, chi-square tests were used while Mann-Whitney U test was used for continuous variables. Regression models were used to measure severity. RESULTS: Impactions were greater in females (119/207; 57.5%). No significant differences between unilateral (100/207; 49.3%) and bilateral (107/207; 51.7%) (P > 0.05). Out of 314 impactions, 105 (33.4%) were mild, 118 (37.58%) moderate and 91 (28.98%) severe. Severe impactions were primarily buccal (44/ 91; 48.3%), in the occlusal ½ of the adjacent incisor root (38/ 91, 41.7%), mesial to the distal border of central incisor (47/91, 51.6%), with sagittal angle value + >45 ̊ (46/ 91, 50.5%) and mesial tip + >30 ̊ (86/ 91, 94.5%). CONCLUSIONS: Severely impacted canines had their crowns buccal, closer to occlusal plane and mesial to the distal border of the central incisor with greater than 45-degree buccal inclination and greater than 30-degree mesial tip. The sagittal angle can have a significant impact on the severity of impaction. A new classification system was proposed to quantify severity.

Three-dimensional Assessment of Temporomandibular Joint Volume, and Condylar and Glenoid-fossa Morphology: A Cone-beam Computed Tomography Study.

Background: The condylar and glenoid fossa morphology can alter in patients with temporomandibular disorders (TMD), which can lead to changes in the temporomandibular joint (TMJ) space volume. Volumetric evaluation of TMJ can represent the entire three-dimensional (3D)-joint space between the condyle and glenoid fossa. Aims: To perform 3D assessment of TMJ volume, condylar, and glenoid-fossa morphology using cone-beam computed tomography and evaluate the correlation between these parameters. Settings and Design: Thirty-four patients (age: 13.50 years) who had no previous history of TMD were included. Materials and Methods: The volume of TMJ space was measured and divided into anterior, posterior, medial, and lateral TMJ volume. The antero-posterior (AP) and medio-lateral (ML) condylar width, AP and ML glenoid-fossa width, and glenoid-fossa depth were evaluated. Statistical Analysis Used: Statistical analyses were performed with R software at a 0.05 significance level. Each parameter was compared between the left and right sides using a paired-t test. The correlations between the parameters were obtained by the Pearson correlation coefficient. Results: There was no significant difference between lateral and medial TMJ volume; however, posterior TMJ volume was significantly greater than anterior TMJ volume. A significant correlation was observed between AP glenoid-fossa width and TMJ volume, glenoid-fossa depth and TMJ volume, AP position of the condyle and anterior TMJ volume, ML position of the condyle and medial TMJ volume, glenoid-fossa width and condyle width in AP and ML dimension, glenoid-fossa depth and AP glenoid-fossa width. Conclusions: In addition to the evaluation of condylar and glenoid-fossa morphology, assessment of TMJ space volume is important for comprehensive evaluation of the joint.

Learning Cephalometric Landmarks for Diagnostic Features Using Regression Trees.

Lateral cephalograms provide important information regarding dental, skeletal, and soft-tissue parameters that are critical for orthodontic diagnosis and treatment planning. Several machine learning methods have previously been used for the automated localization of diagnostically relevant landmarks on lateral cephalograms. In this study, we applied an ensemble of regression trees to solve this problem. We found that despite the limited size of manually labeled images, we can improve the performance of landmark detection by augmenting the training set using a battery of simple image transforms. We further demonstrated the calculation of second-order features encoding the relative locations of landmarks, which are diagnostically more important than individual landmarks.

Anabolic Response of Intermittent Parathyroid Hormone and Alendronate on the Osteochondral Tissue of TMJ.

OBJECTIVE: To characterize the effects of parathyroid hormone (PTH) and alendronate (Alend) on the osteochondral tissue of temporomandibular joint (TMJ). MATERIALS AND METHODS: Ninety-six male and female transgenic reporter mice, 4 to 5 weeks old were divided into 6 groups: (1) Control group: Saline was injected daily for 14 days; (2) PTH: PTH was injected daily for 14 days; (3) Alend: Alend was injected every alternate days for 14 days; (4) Combined PTH and Alend: PTH was injected daily and Alend injected every alternate days for 14 days; (5) PTH then Alend: PTH was injected daily for 14 days followed by Alend injections in alternate days for 14 days; and (6) PTH wait Alend: PTH was injected daily for 14 days. There was a waiting period of 1 week before administration of Alend in alternate days for 14 days. Mice were injected with 5-ethnyl-2'-deoxyuridine (EdU), 48 and 24 hours prior to euthanization. RESULTS: There was significant increase in bone volume and decrease in osteoclastic activity in groups in which Alend was administered after PTH in both gender. There was significant increase in cartilage thickness with PTH or Alend alone in females, whereas in males, PTH alone led to increase in cartilage thickness. Chondrocyte apoptosis was significantly decreased with PTH or Alend alone in both male and female. Matrix metallopeptidase 13, and aggreganase-2 (ADAMTS5) expression were significantly decreased with PTH and Alend alone in both gender. CONCLUSION: PTH and Alend administration causes anabolic effects in the osteochondral tissue of TMJ.

Accuracy of Patient-specific Soft-tissue Prediction Algorithms for Maxillomandibular Surgery in Class III Patients.

Context: Improved esthetics is an important factor for most patients undergoing orthognathic surgery. Thus, a treatment simulation that can provide patients with a realistic view of the esthetic outcome after surgery is important in clinical practice. Aims: To evaluate the accuracy of simulations generated using algorithms specific for patient's type of malocclusion and surgical procedure compared to nonspecific algorithms. Settings and Design: A total of 36 patients (average age 18.41 years) who had undergone maxillary advancement and mandibular setback for Class III malocclusion were included. Subjects and Methods: The presurgical and postsurgical cone-beam computed tomography scans were used to generate the lateral cephalograms and the surgical simulations were created with the patient-specific algorithm (specific for Class III patients) and the nonspecific algorithm (default algorithm not specific for any particular malocclusion or type of surgery) using the treatment simulation feature in Dolphin Imaging software. The accuracy of the simulations was examined by comparing the soft-tissue changes in the surgical simulations with the postsurgical result. Statistical Analysis Used: Statistical analyses were performed with SPSS-software at 0.05 significance level. For the mean difference between the postsurgical and surgical-simulation landmarks, a paired sample t-test (Student's t-test) was performed. Results: Patient-specific algorithms were accurate in vertical prediction of lower lip, B', tip of nose, upper lip, and horizontal prediction of pogonion'. Whereas the nonspecific algorithm was accurate in the horizontal prediction of the lower lip, pogonion', and menton'. Conclusions: Patient-specific and nonspecific algorithms for generating surgical simulations showed different accuracy for vertical and horizontal predictions of the parameters.

Comparable Skeletal and Dental Movements Achieved Using Conventional and Surgery-First Techniques in Class III Patients.

PURPOSE: The surgery-first (SF) approach to orthognathic surgery has been proposed as a more efficient method to correct the dentofacial deformity. This study aimed to evaluate if the magnitude of skeletal and dental changes achieved in Class III patients treated with either conventional orthognathic surgery (COS) or SF techniques differ. METHODS: A retrospective cohort study of Class III orthognathic surgery patients between January 2006 and May 2020 with available pre- and post-treatment lateral cephalograms was conducted at an academic institution. The primary predictor variable was surgery technique: COS or SF. Assessed outcome variables included cephalometric skeletal parameters: SNA, SNB, ANB, Wits Appraisal, Sn-GoGn, and FMA; and dental parameters: U1-SN, U1-NA (°), U1-NA (mm), L1-NB (°), L1-NB (mm), and overjet. Within-group posttreatment parameters were analyzed with paired t tests. Pretreatment, posttreatment, and between-group parameter changes were analyzed by 2-sided 2-sample independent t tests. Potential covariates, including gender, surgical procedure, previous conventional treatment, extractions (excluding 3rd molars), crowding, and midline discrepancy, were analyzed using Fisher exact tests. RESULTS: Thirty-nine subjects were included in this study: 1) 21 COS (age: 20.9 ± 8.7 years) and 2) 18 SF (age: 19.6 ± 5.0 years). Cohorts were comparable (P > .05) for all analyzed covariates. COS showed statistically significant increases in L1-GoGn (3.31 ± 6.23°; P = .024), overjet (4.26 ± 3.99 mm; P < .001), ANB (3.5 ± 2.79°; P < .001), SNA (3.5 ± 1.85°; P < .001), and Wits Appraisal (3.78 ± 4.97 mm; P = .002). SF showed statistically significant increases in L1-GoGn (4.19 ± 4.85°; P = .002), L1-NB (3.08 ± 4.13°; P = .006), L1-NB (0.79 ± 1.35 mm; P = .023), overjet (5.82 ± 2.96 mm; P < .001), ANB (5.51 ± 3°; P < .001), SNA (4.13 ± 2.38°; P < .001), and Wits Appraisal (5.92 ± 3.42 mm; P < .001) and statistically significant decreases in U1-NA (-3.69 ± 7.35°; P = .048) and SNB (-1.38 ± 2.14°; P = .014). There were no statistically significant differences in skeletal or dental parameters between groups when adjusted for pretreatment levels of that parameter. The mean treatment duration was 38 months (standard deviation = 12.7) in COS and 17.6 months (standard deviation = 5.2) in SF. CONCLUSIONS: The results show that skeletal and dental changes between groups were not statistically different, despite an average 20-month difference in treatment duration. This suggests that either technique can be used to achieve comparable degrees of skeletal and dental movement in Class III patients.

Radiographic and histological assessment of root resorption associated with conventional and mini-screw assisted rapid palatal expansion: a systematic review.

BACKGROUND AND OBJECTIVES: The aim of this systematic review and meta-analysis was to evaluate root resorption after maxillary expansion with conventional rapid palatal expansion (RPE) and mini-screw assisted rapid palatal expansion appliances (MARPE) using 2D and 3D radiographic methods and histologic methods of measuring root resorption. SEARCH METHODS AND SELECTION CRITERIA: A search of PubMed/MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, CINAHL, Web of Science, Global Index Medicus, Dissertations & Theses Global, ClinicalTrials.gov registry, ISRCTN Registry, National Research Register, OpenGrey, and the Trip Database was performed. The studies that had analysed root resorption after RPE or MARPE were selected for the systematic review. DATA COLLECTION AND ANALYSIS: The database research, elimination of duplicate studies, data extraction, and risk of bias were performed by the authors independently and in duplication. This systematic review included prospective studies to evaluate root resorption following RPE after tooth-borne (TB), tooth-tissue borne (TTB), bone-borne (BB), and tooth-bone borne (TBB) expansion appliances. RESULTS: A total of 13 prospective trials (six randomized clinical trials and seven non-randomized prospective clinical trials) were identified for inclusion in this systematic review. Histological studies revealed that most teeth experience root resorption on the buccal surfaces after maxillary expansion. MARPE designs with BB and TBB expansion appliances were found to lead to reduced volumetric root resorption than conventional RPE using micro-computed tomography. However, one study using cone beam computed tomography showed no difference in the root resorption with MARPE and RPE designs. CONCLUSIONS AND IMPLICATIONS: Maxillary expansion with RPE can lead to root resorption of maxillary posterior teeth. Root resorption occurs more frequently on buccal surfaces on maxillary posterior teeth. Limited evidence suggests that MARPE may lead to reduced root resorption than RPE. REGISTRATION: This systematic review was conducted following the Cochrane handbook for systematic reviews and interventions and reported according to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The protocol was registered at PROSPERO database (https://www.crd.york.ac.uk/prospero/; registration number: PROSPERO CRD42021271181).