Evaluation of a 3D-Printed Cleft Palate Obturator Using a Low-Dose Cone Beam Computed Tomography Acquisition Protocol: A Proof-of-Concept Study.

Cone beam computed tomography (CBCT) technology is increasingly utilized in the head and neck region and is valuable in treatment planning for cleft palate patients, potentially enabling the creation of 3D-printed obturators to assist with feeding and speech. This technical report investigates the feasibility of using data from a 360-degree CBCT scan to accurately produce a cleft palate obturator and assesses whether a lower-dose 180-degree CBCT scan can achieve a comparable result. A simulated cleft palate was crafted on a dehydrated human skull, which was then scanned using both 360-degree and 180-degree CBCT scanning protocols. Two obturators were digitally designed based on the segmented images from each scan and subsequently 3D printed. Evaluation of the segmented images and 3D-printed obturators from both protocols demonstrated clear visualization of anatomical landmarks and identical scores across all parameters, suggesting that the 180-degree CBCT scan can produce an obturator of comparable quality to that of the 360-degree scan, with the added benefit of reduced radiation exposure.

Variability associated with maxillary infrazygomatic crest and palatal bone width, height, and angulation in subjects with different vertical facial growth types: a retrospective cone-beam computed tomography study.

OBJECTIVES: To assess the infrazygomatic crest (IZC) and palatal bone width, height, and angulation in patients with different vertical facial growth types as potential miniscrew insertion sites. MATERIALS AND METHODS: In this retrospective cone-beam computed tomography study, 162 subjects (81 males and 81 females, mean age 16.05 ± 0.65 years) were included. They were divided into three groups (hypodivergent, normodivergent, and hyperdivergent) based on the Frankfort mandibular plane angle. Ten buccal bone measurements were made at two different coronal sections: maxillary first molar mesiobuccal and distobuccal roots (bilaterally). Six palatal bone measurements were made on a sagittal section at the maxillary central incisors (bilaterally). A total of 32 measurements per subject were considered in the study. RESULTS: No significant difference was observed for the IZC (width and angle) at the maxillary first molar mesiobuccal root. A comparison of normodivergent and hyperdivergent groups for buccal width at the distobuccal root of the first molar showed significant differences. Palatal bone thickness at the level of 2 mm distal to the apex of the central incisor was significantly higher for the hyperdivergent group (10.43 mm) compared with the normodivergent (7.58 mm) and hypodivergent groups (7.83 mm). CONCLUSIONS: Hyperdivergent subjects tend to present a longer and deeper IZC and increased palatal bone thickness compared with other groups. The recommended insertion angle for the IZC mini-implant at 3 mm from the alveolar crest should be between 75.5° and 77°.

Newly Developed Low Dose 180-degree CBCT Protocol Reduces Radiation Dose Without Compromising Diagnostic Value.

PURPOSE: To compare the standard 360-degree CBCT acquisition protocol to the low dose 180-degree CBCT protocol for implant planning. MATERIALS AND METHODS: Two groups of patients, each consisting of 35 patients, were included in the study. The first group was imaged with the conventional 360-degree CBCT protocol, and the second group was imaged with the low dose 180-degree CBCT protocol. The primary outcome of this study was the number of scans that needed to be repeated due to poor image quality. In addition, six secondary parameters were evaluated quantitatively and qualitatively. RESULTS: The results showed that there was no need to repeat any of the CBCT scans that were obtained in either group, which showed that 360-degree and 180-degree protocols had comparable image quality. As for the secondary parameters, the results showed that the evaluators were able to evaluate the six chosen parameters in a comparable manner. CONCLUSIONS: The 180-degree low dose CBCT scan is a viable option for dental implant treatment planning in the posterior mandible as it provides comparable and adequate information regarding accuracy of measurements, identification of critical structures, evaluation of bone quality, and any pathology.

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.

Bridging Neuroscience and Robotics: Spiking Neural Networks in Action.

Robots are becoming increasingly sophisticated in the execution of complex tasks. However, an area that requires development is the ability to act in dynamically changing environments. To advance this, developments have turned towards understanding the human brain and applying this to improve robotics. The present study used electroencephalogram (EEG) data recorded from 54 human participants whilst they performed a two-choice task. A build-up of motor activity starting around 400 ms before response onset, also known as the lateralized readiness potential (LRP), was observed. This indicates that actions are not simply binary processes but rather, response-preparation is gradual and occurs in a temporal window that can interact with the environment. In parallel, a robot arm executing a pick-and-place task was developed. The understanding from the EEG data and the robot arm were integrated into the final system, which included cell assemblies (CAs)-a simulated spiking neural network-to inform the robot to place the object left or right. Results showed that the neural data from the robot simulation were largely consistent with the human data. This neurorobotics study provides an example of how to integrate human brain recordings with simulated neural networks in order to drive a robot.

Evaluation of Skeletal and Dentoalveolar Changes in Patients With Class II Div 1 Malocclusion Treated With Twin Block Appliance.

Objective The study was focused on evaluating the change in mandibular morphology following the Twin Block appliance therapy and recording its effect on the maxilla and maxillary dentoalveolar complex. Also, the results of the Twin Block appliance between males and females were compared.  Material and methods In this two-armed retrospective cephalometric study, 30 patients (mean age 12 years) treated with Twin Block appliance for the period of 8-12 months were chosen, and their records were obtained to analyze. These results were compared with 15 control subjects of the same age group chosen from the American Association of Orthodontics Foundation (AAOF) growth legacy collection: Michigan Growth Study Class II subjects. Cephalometric tracing was done, and data was processed for descriptive statistical analysis. Results Paired sample t-test and ANOVA test were performed to evaluate the differences in the pre-treatment (T1) and post-functional (T2) values. ∠ANB showed a mean difference of -4.71°±1.55° for males and 6.22°±6.78° for females, which is significant. The mandibular length (Co-Gn), for male subjects, the mean difference was 5.14±1.74 mm, and for female subjects, it was 6±2mm, which is highly significant; 49.88% of skeletal changes and 50.12% of dentoalveolar changes were reported to bring about Class II correction with Twin Block. Conclusion A successful increase in mandibular length was achieved using a Twin Block as a functional appliance. Also, the significant maxillary restraining effect was recorded. More skeletal changes were observed in males than females.

Newly Developed Low Dose 180-degree CBCT Protocol Reduces Radiation Dose Without Compromising Diagnostic Value.

PURPOSE: To compare the standard 360-degree CBCT acquisition protocol to the low dose 180-degree CBCT protocol for implant planning. MATERIALS AND METHODS: Two groups of patients, each consisting of 35 patients, were included in the study. The first group was imaged with the conventional 360-degree CBCT protocol, and the second group was imaged with the low dose 180-degree CBCT protocol. The primary outcome of this study was the number of scans that needed to be repeated due to poor image quality. In addition, six secondary parameters were evaluated quantitatively and qualitatively. RESULTS: The results showed that there was no need to repeat any of the CBCT scans that were obtained in either group, which showed that 360-degree and 180-degree protocols had comparable image quality. As for the secondary parameters, the results showed that the evaluators were able to evaluate the six chosen parameters in a comparable manner. CONCLUSION: The 180-degree low dose CBCT scan is a viable option for dental implant treatment planning in the posterior mandible as it provides comparable and adequate information regarding accuracy of measurements, identification of critical structures, evaluation of bone quality, and any pathology.

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.

Vibrational Force on Accelerating Orthodontic Tooth Movement: A Systematic Review and Meta-Analysis.

This study aimed to systematically gather and analyze the current level of evidence for the effectiveness of the vibrational force in accelerating orthodontic tooth movement (OTM). This systematic review was conducted using three electronic databases: Scopus, PubMed, and Google Scholar until March 2022. The search was done through the following journals: European Journal of Orthodontics, American Journal of Orthodontics and Dentofacial Orthopedics, The Angle Orthodontist, Progress in Orthodontics, and Seminars in Orthodontics. Human or animal studies that have evaluated the effect of vibrational force on the rate of OTM were selected. A meta-analysis was performed for the rate of canine movement per month. Database research, elimination of duplicate studies, data extraction, and risk of bias assessment were performed by authors independently and in duplication. A fixed and random-effect meta-analysis was performed to evaluate the effect of vibrational forces. A total of 19 studies (6 animal and 13 human studies) that met the inclusion criteria were included. Meta-analysis was performed based on four human clinical trials. Three out of four studies showed no significant difference in the rate of canine movement between vibrational force and control groups. The limitation of this study was the small sample size and significant heterogeneity among the studies. Although vibrational forces have been shown to accelerate OTM in experimental studies, the results are inconsistent in clinical studies. The inability to apply desired peak load to the targeted teeth may be the main factor in inconsistent clinical outcomes.

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).

Management of Anterior Open Bite and Skeletal Class II Hyperdivergent Patient with Clear Aligner Therapy.

In orthodontics, patients with hyperdivergent facial types or problems in the vertical dimension are often challenging to treat with predictable treatment results. Conventionally along with fixed appliances, a headgear, posterior bite block, extraction, temporary anchorage devices, or orthognathic surgery are preferable approaches to treat such patients. This case report illustrates a non-extraction, non-surgical orthodontic treatment of 5 mm anterior open bite in a non-growing adult patient, utilizing clear aligner therapy.

Evaluation of interproximal reduction in individual teeth, and full arch assessment in clear aligner therapy: digital planning versus 3D model analysis after reduction.

AIM: To evaluate the correspondence between the interproximal reduction (IPR) performed clinically and that programmed in ClinCheck® and further assess which teeth showed an amount of implemented IPR (I-IPR) that corresponds with that programmed in ClinCheck®. MATERIALS AND METHODS: Pre- (T0) and post-treatment (T1) ClinCheck® digital models for 75 subjects (30 males and 45 females), mean age (38 ± 15) years, were included. To calculate the amount of I-IPR, Ortho Analyzer software (3Shape, Copenhagen, Denmark) was used to measure the mesiodistal widths for the maxillary and mandibular teeth from second premolar to the contralateral second premolar on the initial (T0) and final (T1) STL models. I- IPR performed by tooth was obtained by comparing the mesiodistal width of each tooth at T0 and T1. The amount of programmed IPR (P-IPR) in ClinCheck® was compared to that implemented clinically using the following formula: IPR difference = (P-IPR) - (I-IPR). RESULTS: Statistically significant differences were observed between the average value of digitally programmed and implemented IPR per tooth for both the maxillary (p < .0001) and mandibular (p < .0001) teeth. The mean P-IPR for the maxillary teeth was 0.28 ± 0.16 mm versus the mean I-IPR of 0.15 ± 0.15 mm. In the mandibular arch, the mean P-IPR was 0.31 ± 0.17 mm, while the I-IPR was 0.17 ± 0.16 mm. The mean I-IPR was consistently lower than the mean P-IPR regardless of teeth and sites (p < 0.0001). The difference between the P-IPR compared to the I-IPR was larger for mandibular anterior teeth than for maxillary anterior teeth (p = 0.0302) and larger for maxillary posterior teeth than mandibular posterior teeth (p = 0.0059). CONCLUSION: The amount of implemented-IPR in clear aligner therapy is less than that digitally programmed for most teeth. Regardless of the regions, I-IPR was consistently lower than that programmed. Mandibular anterior teeth and maxillary posterior teeth showed greater discrepancy between P-IPR and I-IPR than the maxillary anterior and mandibular posteriors. Further prospective studies are needed to determine the factors affecting the precision of IPR and the clinical implications of a significantly reduced I-IPR on treatment outcomes.

Racial and gender differences of cervical vertebral maturation staging between African Americans versus Caucasian patients of various age groups: A retrospective study.

BACKGROUND AND OBJECTIVE: The primary purpose of this study was to compare CVM staging between African American (AA) and Caucasian (CC) subjects, grouped based on gender. The secondary objectives were to conduct a CVM comparison of (1) male vs. female subjects, grouped based on their race, and (2) AA vs. CC subjects, categorized based on their age group. MATERIALS AND METHODS: All patients between 8-18 years of age (University of XXX), meeting the criteria, were included between the period of the year 2007 to 2020. Three blinded independent evaluators analysed the lateral cephalograms for a 6-stage CVM system (CS1 to CS6) as described by McNamara and Franchi. Samples were divided based on race, gender, and age to conduct the statistical analysis for racial and gender comparisons. RESULTS: Out of the initial 1,300 lateral cephalograms, 1,276 with the mean age: 12.7 years SD 2.5 years, and median CVM: 4 (IQR: 25% percentile- 2 and 75% percentile- 4) were included. Gender-specific racial age comparison showed no significant differences for male subjects for most of the CVM stages (P>0.05). Overall and race-specific gender comparison of age showed significant differences for almost all CVM stages (P<0.05). No significant difference of CVM was found on racial comparison for overall, females (P=0.6131) or males (P=0.0825) subjects. On age-specific racial comparison, AA girls (8-10 years) were skeletally more mature than CC girls (P=0.0143); over 14-year-old CC girls (P<0.0001) and over 16-year-old CC boys (P=0.0008), being skeletally more mature than AA boys of the same age. CONCLUSIONS: There was no significant difference between AA and CC subjects on gender-specific comparisons for most of the CVM stages. A significant difference of age was observed for most of the CVM stage between male and female subjects on race-specific comparisons. Female patients were ahead in skeletal maturity as compared to males for each CVM stage. The CVM for 8-12-year-old AA females was significantly higher than that of the CC females, whereas the CVM for>14-year-old CC females was significantly higher than AA females.

Long-term assessment of conventional and mini-screw-assisted rapid palatal expansion on the nasal cavity.

OBJECTIVES: To evaluate the long-term effects of mini-screw-assisted rapid palatal expansion (MARPE), rapid palatal expansion (RPE), and controls on the nasal cavity with cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 180 CBCT scans that were part of a previous randomized trial were evaluated retrospectively for 60 patients at pretreatment (T1), postexpansion (T2), and posttreatment (T3). Patients were randomly assigned into 3 groups: MARPE, RPE, and controls (time period T1 to T3; MARPE: 2 years 8 months; RPE: 2 years 9 months; control: 2 years 7 months). Nasal height, nasal length, nasion-ANS height, ANS-PNS length, pyriform height, and nasal septal deviation angle were measured. The changes in alar width, alar base width, anterior nasal cavity width, posterior nasal cavity width, maxillary intermolar width, and maxillary intercanine width were also evaluated. RESULTS: The alar base width, posterior nasal cavity width, anterior nasal cavity width, maxillary intercanine width, and maxillary intermolar width significantly increased (P < .05), and the nasal septal deviation angle significantly decreased (P < .05) in both the MARPE and RPE groups as compared with controls in the short term. In the long term, the nasal septal deviation angle was significantly decreased (P < .05) in the MARPE and RPE groups as compared with controls, and the posterior nasal cavity width was significantly increased (P < .05) in the MARPE group compared with the RPE group and controls. CONCLUSIONS: MARPE and RPE led to a significant increase in the nasal cavity and alar base width compared with controls in the short term. In the long term, a significant increase was observed only in the posterior nasal cavity width with MARPE. Both MARPE and RPE led to a minimal decrease in nasal septal deviation angle in comparison with controls.

Where is the center of resistance of a maxillary first molar? A 3-dimensional finite element analysis.

INTRODUCTION: The center of resistance (CRes) is regarded as the fundamental reference point for predictable tooth movement. Accurate estimation can greatly enhance the efficiency of orthodontic tooth movement. Only a handful of studies have evaluated the CRes of a maxillary first molar; however, most had a low sample size (in single digits), used idealized models, or involved 2-dimensional analysis. The objectives of this study were to: (1) determine the 3-dimensional (3D) location of the CRes of maxillary first molars, (2) evaluate its variability in a large sample, and (3) investigate the effects of applying orthodontic load from 2 directions on the location of the CRes. METHODS: Cone-beam computed tomography scans of 50 maxillary molars from 25 patients (mean age, 20.8 ± 8.7 years) were used. The cone-beam computed tomography volume images were manipulated to extract 3D biological structures via segmentation. The segmented structures were cleaned and converted into virtual mesh models made of tetrahedral triangles having a maximum edge length of 1 mm. The block, which included the molars and periodontal ligament, consisted of a mean of 7753 ± 2748 nodes and 38,355 ± 14,910 tetrahedral elements. Specialized software was used to preprocess the models to create an assembly and assign material properties, interaction conditions, boundary conditions, and load applications. Specific loads were applied, and custom-designed algorithms were used to analyze the stress and strain to locate the CRes. The CRes was measured in relation to the geometric center of the buccal surface of the molar and the trifurcation of the molar roots. RESULTS: The average location of the CRes for the maxillary first molar was 4.94 ± 1.39 mm lingual, 2.54 ± 2.7 mm distal, and 7.86 ± 1.66 mm gingival relative to the geometric center of the buccal surface of the molar and 0.136 ± 1.51 mm lingual (P <0.01), 1.48 ± 2.26 mm distal (P <0.01), and 0.188 ± 1.75 mm gingival (P >0.01) relative to the trifurcation of the molar roots. In the anteroposterior (y-axis) and the vertical (z-axis) planes, the CRes showed significant association with root divergence (P <0.01). CONCLUSIONS: The CRes of the maxillary first molar was located apical and distal to the trifurcation area. It showed significant variation in its location. The 3D location of and also varied with the force direction. In some samples, this deviation was large. For accurate and predictable movement, tooth-specific CRes need to be calculated.

Comparison of anterior maxillary and mandibular alveolar parameters in African American and Caucasian women: A retrospective pilot study.

PURPOSE: The primary objective of this study was to analyze the thickness and height of alveolar bone around the maxillary and mandibular incisors. Additionally, this study aimed to compare bone parameters between Caucasian (CC) and African American (AA) female patients. MATERIALS AND METHODS: In this retrospective pilot study, 50 female subjects (25 CC and 25 AA) were included. The inclusion criteria were AA or CC women between the ages of 18 and 50 with a normo-divergent facial pattern and Angle's class I, end-on class II, or mild class III malocclusion. The distance from the cementoenamel junction (CEJ) to the buccal and lingual alveolar crest; the alveolar ridge thickness at the mid-root and apex; and the buccal and lingual bone thickness at 3, 6, and 9 mm from the CEJ were measured. RESULTS: No significant difference was found (P>0.05) in the cortical bone thickness at 3 mm, 6 mm, or 9 mm from the alveolar crest between CC and AA populations for most measurements. A significant difference in bone thickness was found (P<0.05) for the lingual surface of the central incisor, with maxillary bone thickness found to be higher than mandibular bone thickness. The measurements of lingual thickness were larger than those of buccal thickness for both races. CONCLUSION: There were no differences in maxillomandibular anterior alveolar bone measurements between normo-divergent adult AA and CC women, except for a few parameters at varying locations. However, future studies can be planned based the current pilot study data, which may provide valuable information.

Survival estimates and risk factors for failure of palatal and buccal mini-implants.

OBJECTIVES: The primary objective was to compare the success and survival rates of palatal and buccal mini-implants for different locations and treatment requirements. The secondary objective was to evaluate risk factors influencing the survival of mini-implants. MATERIALS AND METHODS: In this retrospective cohort, records of 127 orthodontic patients with 257 mini-implants were included after imposing inclusion/exclusion criteria. Along with the implant failure data, factors such as age, sex, transverse location, anteroposterior location, and purpose of mini-implants were recorded. Kaplan-Meier survival analysis was used to draw the curves and a Nathan Mantel-David Cox test to compare variables. RESULTS: The failure rate of palatal mini-implants was 8.5%, whereas the failure rate for buccal shelf mini-implants was 68.7% (P < .0001). A significant difference was that the survival rates of palatal mini-implants were dependent on the purpose of the mini-implants and, for the buccal mini-implants, they were dependent on the skeletal malocclusion and location type of mini-implants (P < .05). CONCLUSIONS: The overall survival rate of palatal mini-implants was high, at 91.5%. Of the buccal mini-implants, inter-radicular mini-implants had the highest survival rate for 12 (75.5%) and 24 (71.9%) months, while buccal shelf mini-implants had the lowest success and survival rates for 12 (31.3%) and 24 (20.8%) months. Class III malocclusion had the lowest survival rate for the buccal mini-implants (65.3% and 54.2%) for 12 and 24 months.

The effect of the local administration of biological substances on the rate of orthodontic tooth movement: a systematic review of human studies.

BACKGROUND: The influence of different biological agents on the rate of orthodontic tooth movement (OTM) has been extensively reviewed in animal studies with conflicting results. These findings cannot be extrapolated from animals to humans. Therefore, we aimed to systematically investigate the most up-to-date available evidence of human studies regarding the effect of the administration of different biological substances on the rate of orthodontic tooth movement. METHODS: A total of 8 databases were searched until the 16th of June 2020 without restrictions. Controlled randomized and non-randomized human clinical studies assessing the effect of biological substances on the rate of OTM were included. ROBINS-I and the Cochrane Risk of Bias tools were used. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: A total of 11 studies (6 randomized clinical trials and 5 prospective clinical trials) were identified for inclusion. Local injections of prostaglandin E1 and vitamin C exerted a positive influence on the rate of OTM; vitamin D showed variable effects. The use of platelet-rich plasma and its derivatives showed inconsistent results, while the local use of human relaxin hormone showed no significant effects on the rate of OTM. LIMITATIONS: The limited and variable observation periods after the administration of the biological substances, the high and medium risk of bias assessment for some included studies, the variable concentrations of the assessed biological agents, the different experimental designs and teeth evaluated, and the variety of measurement tools have hampered the quantitative assessment of the results as originally planned. CONCLUSIONS AND IMPLICATIONS: Despite the methodological limitations of the included studies, this systematic review provides an important overview of the effects of a variety of biological agents on the rate of tooth movement and elucidates the deficiencies in the clinical studies that have been conducted so far to evaluate the effectiveness of these agents in humans, providing some guidelines for future robust research. TRIAL REGISTRATION: PROSPERO ( CRD42020168481 , www.crd.york.ac.uk/prospero ).

Variability of the maxillary suture maturation and density in the subjects with different sex and growth status.

INTRODUCTION: The objective of this study was to classify median palatine suture (MPS) maturation type in young and adult patients. Additionally, we compared MPS maturity type and density based on sex and growth status. MATERIALS AND METHODS: In this retrospective cone beam computed tomography study, we included a total of 221 subjects, grouped based on sex and growth status. Once scans were aligned and oriented in the sagittal view, we conducted our evaluations on the axial sections. Based on interdigitation and shape, the MPS were categorized into Maturation Types A through E. Additionally, MPS density was measured as Hounsfield unit equivalent pixel intensity value scale for anterior and posterior sutural regions. RESULTS: The majority of male (39%) and female (42%) subjects had MPS Maturation Type C. A maximum number of growing (42%) patients had Type C and nongrowing subjects (39%) had Type E sutures. The sex comparison showed significantly lower (p < .001) MPS density for both anterior and posterior regions in males when compared to females. Additionally, for the posterior region, nongrowing males had significantly lower (p < .001) MPS density when compared to nongrowing females. Subgroup comparisons of the MPS densities between growing and nongrowing males and growing and nongrowing females showed a significant difference (p < .001). CONCLUSION: Classification of the MPS based on the maturation types provides a reliable predictor for orthodontic treatment planning. MPS density is significantly higher in females as compared to males. Similarly, nongrowing individuals have significantly higher MPS density compared to growing individuals for both anterior and posterior locations.

Variability associated with mandibular buccal shelf area width and height in subjects with different growth pattern, sex, and growth status.

INTRODUCTION: The primary objective of the study was to quantitatively analyze the width and height of the mandibular buccal shelf area (MBS) at 3 different potential locations for mini-implant placement. In addition, we aimed to compare and contrast the bone parameters of the MBS to study the correlation between different growth status (growing or nongrowing), facial types (hypodivergent, normodivergent, and hyperdivergent), and sex differences (male or female). METHODS: In this retrospective cone-beam computed tomography study, 678 subjects were included. They were divided into groups according to growth status, facial type, and sex. Scans were imported into the reconstruction program and were aligned in 3 different steps. Measurements were made at 6 different coronal sections: mandibular first molar distal root, second molar mesial root, and second molar distal root (bilaterally). The roots of mandibular molars were used as a reference to measure the width and the roof of the inferior alveolar canal to measure the height of the buccal shelf area. Intraobserver reliability was assessed by measuring the width and height of MBS in 20 randomly selected subjects. RESULTS: No significant difference (P > 0.05) was found in the width of MBS between males and females. MBS width increased, and height decreased (P < 0.0001) as moved distally from the first molar distal root to the second molar distal root in all 3 facial types irrespective of age or sex. The hypodivergent facial type had significantly greater bone width than the hyperdivergent facial type at all the 3 locations in both males and females. The hypodivergent facial type had significantly less (P < 0.0001) bone height than the hyperdivergent group at all the 3 locations irrespective of age or sex. CONCLUSIONS: The optimal site for MBS mini-implant is the buccal region of the distal root of mandibular second molars. Hypodivergent patients have more width and less height of MBS compared with hyperdivergent patients. MBS mini-implants are not advised for growing patients because of proximity to developing roots.