Structural insights into the HBV receptor and bile acid transporter NTCP.

Around 250 million people are infected with hepatitis B virus (HBV) worldwide1, and 15 million may also carry the satellite virus hepatitis D virus (HDV), which confers even greater risk of severe liver disease2. The HBV receptor has been identified as sodium taurocholate co-transporting polypeptide (NTCP), which interacts directly with the first 48 amino acid residues of the N-myristoylated N-terminal preS1 domain of the viral large protein3. Despite the pressing need for therapeutic agents to counter HBV, the structure of NTCP remains unsolved. This 349-residue protein is closely related to human apical sodium-dependent bile acid transporter (ASBT), another member of the solute carrier family SLC10. Crystal structures have been reported of similar bile acid transporters from bacteria4,5, and these models are believed to resemble closely both NTCP and ASBT. Here we have used cryo-electron microscopy to solve the structure of NTCP bound to an antibody, clearly showing that the transporter has no equivalent of the first transmembrane helix found in other SLC10 proteins, and that the N terminus is exposed on the extracellular face. Comparison of our structure with those of related proteins indicates a common mechanism of bile acid transport, but the NTCP structure displays an additional pocket formed by residues that are known to interact with preS1, presenting new opportunities for structure-based drug design.

Cs-treatments in Kesterite Thin-Film Solar Cells for Efficient Perovskite Tandems.

Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells are an attractive choice for a bottom cell of the low-cost and environmental tandem solar cells with perovskite. However, the progress in developing efficient perovskite/CZTSSe tandem solar cells has been hindered by the lack of high performance of the CZTSSe bottom cell. Here, an efficient CZTSSe bottom cell is demonstrated by adopting a facile and effective CsF treatment process. It is found that the CsF treatment not only facilitates grain growth and improves phase homogeneity by suppressing the detrimental deep-level defects and secondary phases, but also induces larger band bending and stronger drift force at the P-N junction. As a result, the carrier extraction/transport can be effectively accelerated, while reducing the interfacial recombination. These combined effects eventually result in a significant performance enhancement from 8.38% to 10.20%. The CsF-treated CZTSSe solar cell is finally applied to the mechanically-stacked perovskite/CZTSSe 4-terminal tandem cell by coupling a semi-transparent perovskite top cell, which exhibits the highest reported tandem efficiency of 23.01%.

Hyaluronic acid stimulation of stem cells for cardiac repair: a cell-free strategy for myocardial infarct.

BACKGROUND: Myocardial infarction (MI), a representative form of ischemic heart disease, remains a huge burden worldwide. This study aimed to explore whether extracellular vesicles (EVs) secreted from hyaluronic acid (HA)-primed induced mesenchymal stem cells (HA-iMSC-EVs) could enhance the cardiac repair after MI. RESULTS: HA-iMSC-EVs showed typical characteristics for EVs such as morphology, size, and marker proteins expression. Compared with iMSC-EVs, HA-iMSC-EVs showed enhanced tube formation and survival against oxidative stress in endothelial cells, while reduced reactive oxygen species (ROS) generation in cardiomyocytes. In THP-1 macrophages, both types of EVs markedly reduced the expression of pro-inflammatory signaling players, whereas HA-iMSC-EVs were more potent in augmenting anti-inflammatory markers. A significant decrease of inflammasome proteins was observed in HA-iMSC-EV-treated THP-1. Further, phospho-SMAD2 as well as fibrosis markers in TGF-ß1-stimulated cardiomyocytes were reduced in HA-iMSC-EVs treatment. Proteomic data showed that HA-iMSC-EVs were enriched with multiple pathways including immunity, extracellular matrix organization, angiogenesis, and cell cycle. The localization of HA-iMSC-EVs in myocardium was confirmed after delivery by either intravenous or intramyocardial route, with the latter increased intensity. Echocardiography revealed that intramyocardial HA-iMSC-EVs injections improved cardiac function and reduced adverse cardiac remodeling and necrotic size in MI heart. Histologically, MI hearts receiving HA-iMSC-EVs had increased capillary density and viable myocardium, while showed reduced fibrosis. CONCLUSIONS: Our results suggest that HA-iMSC-EVs improve cardiac function by augmenting vessel growth, while reducing ROS generation, inflammation, and fibrosis in MI heart.

A finite element analysis of stress distribution with various directions of intermaxillary fixation using orthodontic mini-implants and elastics following mandibular advancement with a bilateral sagittal split ramus osteotomy.

OBJECTIVE: This finite element analysis (FEA) aimed to assess the stress distribution in the mandible and fixation system with various directions of the intermaxillary fixation (IMF) using mini-implants (MIs) and elastics following mandibular advancement with a bilateral sagittal split ramus osteotomy (BSSRO). MATERIALS AND METHODS: A total of nine mandibular advancement models were set according to the position of the MIs (1.6 mm in diameter, 8 mm in length) and direction of the IMF elastics (1/4 inch, 5 oz). Major and minor principal stresses in the cortical and cancellous bones, von Mises stresses in the fixation system (miniplate and monocortical screws), and bending angles of the miniplate were analysed. RESULTS: Compressive and tensile stress distributions in the mandible and von Mises stress distributions in the fixation system were greater in models with a Class III IMF elastic direction and a higher IMF elastic force than in models with a Class II IMF elastic direction and a lower IMF elastic force. The bending angle of the miniplate was negligible. CONCLUSIONS: Stress distributions in the bone and fixation system varied depending on the direction, amount of force, and position of IMF elastics and MIs. Conclusively, IMF elastics in the Class II direction with minimal load in the area close to the osteotomy site should be recommended.

A comparison of maxillary posterior changes following facemask therapy: Skeletal anchorage versus tooth-borne anchorage.

OBJECTIVE: To compare changes in the maxillary posterior structure as seen in cone-beam computed tomography (CBCT) images resulting from facemask therapy using skeletal (miniplate/FM) anchorage versus tooth-borne anchorage (RME/FM). MATERIALS AND METHODS: A retrospective study was conducted on 20 patients divided into the miniplate/FM group (nine patients aged 9.5 ± 1.4 years) and the RME/FM group (11 patients aged 9.2 ± 1.4 years). CBCT images before and after facemask therapy were evaluated to assess changes in the maxillary posterior structure. RESULTS: The miniplate/FM group had greater advancement of the maxilla and midface compared to the RME/FM group (p < .05). Specifically, there was about three times more advancement of the pterygomaxillary suture in the miniplate/FM group than in the RME/FM group (p < .05). Moreover, the advancement of the pterygomaxillary suture was about half the advancement of A point in the miniplate/FM group, while only about 25% in the RME/FM group. Finally, the miniplate/FM group showed an increase in the transverse dimension of the posterior and superior parts of the maxilla (p < .05). CONCLUSION: There was greater forward movement of the pterygomaxillary suture with facemask therapy using the skeletal anchorage compared to tooth-borne anchorage, leading to a more significant advancement of the maxilla and midface.

Early-stage dynamics of chloride ion-pumping rhodopsin revealed by a femtosecond X-ray laser.

Chloride ion-pumping rhodopsin (ClR) in some marine bacteria utilizes light energy to actively transport Cl- into cells. How the ClR initiates the transport is elusive. Here, we show the dynamics of ion transport observed with time-resolved serial femtosecond (fs) crystallography using the Linac Coherent Light Source. X-ray pulses captured structural changes in ClR upon flash illumination with a 550 nm fs-pumping laser. High-resolution structures for five time points (dark to 100 ps after flashing) reveal complex and coordinated dynamics comprising retinal isomerization, water molecule rearrangement, and conformational changes of various residues. Combining data from time-resolved spectroscopy experiments and molecular dynamics simulations, this study reveals that the chloride ion close to the Schiff base undergoes a dissociation-diffusion process upon light-triggered retinal isomerization.

Post-Hair Transplantation Complication: Kinky or Severely Curly Hair.

OBJECTIVE: To investigate the etiology and preventive measures of posttransplant kinky or curly hair growth after female hairline correction surgery. BACKGROUND: Hair transplant surgery can be accompanied by various adverse effects, one of which is severely kinky or curly hair after surgery. Posttransplant kinky or curly hair is not well-understood for its cause or prevention. METHODS: The study was targeted at a total of 980 patients who were confirmed whether they developed kinky or curly hair after female hairline correction surgery. Incidence, surgical method, degree of curliness, predisposed location, characteristics, hair caliber (thin, medium, and thick), and left-right differences were examined. RESULTS: Among the total 980 patients, posttransplant curly hair (PTCH) was manifested in 38(3.9%) patients. None of the patients who underwent surgery at the present clinic developed posttransplant kinky hair; all 38 patients showed PTCH growth. In 36 cases, transplanted hair started to grow in curly patterns around 4 months after surgery. However, the remaining 2 cases showed no curly growth pattern when the transplanted hair was short at postoperative 4 months, but started to grow curly starting at 6 to 8 months after surgery as the hair growth direction was obstructed or compressed by the existing hair. CONCLUSION: Familiarity with the cause, prevention, and management of posttransplant kinky hair and PTCH will be of great help to hair surgeons.

Selective Interbundle Cross-Linking for Lightweight and Superstrong Carbon Nanotube Yarns.

In this study, a range of carbon nanotube yarn (CNTY) architectures was examined and controlled by chemical modification to gain a deeper understanding of CNTY load-bearing systems and produce lightweight and superstrong CNTYs. The architecture of CNTY, which has polymer layers surrounding a compact bundle without hampering the original state of the CNTs in the bundle, is a favorable design for further chemical cross-linking and for enhancing the load-transfer efficiency, as confirmed by in situ Raman spectroscopy under a stress load. The resulting CNTY exhibited excellent mechanical performance that exceeded the specific strength of the benchmark, high-performance fibers. This exceptional strength of the CNTY makes it a promising candidate for the cable of a space elevator traveling from the Earth to the International Space Station given its strength of 4.35 GPa/(g cm-3), which can withstand the self-weight of a 440 km cable.

Comprehensive Assessment of Lower-Face Volume Reduction Using Laser-Assisted Liposuction as an Additive Procedure in Asian Rhytidectomy.

The most important factor that distinguishes a youthful appearance from an aged one is the shape of the lower face. This study aimed to examine the outcome of volume reduction of the lower face using laser-assisted liposuction (SmartLipo) at the time of rhytidectomy in Asians. There were 20 patients (Group 1) for whom only extended deep-plane rhytidectomy were performed, while extended deep-plane rhytidectomy with laser-assisted liposuction was performed on 42 patients (Group 2). This study was performed retrospectively. The FACE-Q questionnaire was given to evaluate the subjective result of the patient. Efficacy was evaluated by measuring the fat quantity at the midpoint and anterior border of the masseter muscle on each side by using an ultrasound scan in Group 2. Then, the correlation between the change in the quantity of fat and the FACE-Q was investigated. The overall satisfaction, and satisfaction for the lower face, jawline, and the area under the chin were significantly higher for Group 2 for which the procedure was concurrently performed in comparison to Group 1. In Group 2, change in the fat was reduced by 21.2% (Rt.) and 22.5% (Lt.) at the mid-point and 24.5% (Rt.) and 26.4% (Lt.) at the anterior border of the masseter muscle. Changes in the fat quantity and lower face satisfaction displayed a significant correlation. With a greater reduction in fat quantity, the score of lower face satisfaction was higher. In addition, with a higher level of satisfaction for the lower face and jawline, the overall satisfaction score displayed a higher positive correlation. Laser-assisted liposuction was useful for the additive procedure at the time of rhytidectomy and improved patient's satisfaction after surgery.

Management of Cowlick in Female Hairline Correction Surgery.

PURPOSE: To investigate the results of two grafting methods to manage CLs in the FHL of women. BACKGROUND: The present study was performed to investigate the results of two grafting methods to manage cowlicks (CLs) in the frontal hairline of women. METHODS: Patients were categorized into two groups based on the grafting method: the matching with the original hair direction (MOD) group and the matching with the CL hair direction (MCD) group. Satisfaction ratings were compared between the two groups. RESULTS: Among 80 patients, 77 had a single CL and 3 had a double CL. In the MOD group, 7 of 12 (58.3%) patients underwent a touch-up procedure for density enhancement with an average of 123 follicular units; the average patient and physician satisfaction ratings were 4.84 and 4.60, respectively. In the MCD group, 7 of 68 (10.3%) patients underwent a touch-up procedure for density enhancement around the CL; the average patient and physician satisfaction ratings were 4.64 and 4.50, respectively. CONCLUSION: In female hairline correction surgery, the surgeon must choose between MOD and MCD by considering the location, shape, and pattern of the CL; the facial shape; and the patient's preference. Delicate graft placement is required to obtain natural-looking results. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors. www.springer.com/00266 .

Precautions and possibilities in orthodontic treatment of periodontally compromised patients: Current recommendations.

OBJECTIVE: Orthodontic treatment plays a crucial role in achieving optimal dental esthetics and functional occlusion. However, when periodontally compromised patients are involved, additional precautions and considerations are critical. This article aims to provide up-to-date recommendations for the orthodontic treatment of periodontally compromised patients. CLINICAL CONSIDERATIONS: Comprehensive diagnosis of the patient's periodontal status, inherent malocclusion, and secondary malocclusion resulting from periodontal disease are essential for achieving optimal esthetics and functional occlusion. This can be facilitated through the use of a simplified checklist. Prior to orthodontic treatment, pre-existing periodontal diseases should be managed. Light and controlled forces should be used to minimize the risk of adverse effects on the periodontium, and any potential traumatic occlusion during tooth movement should be minimized. Furthermore, careful anchorage management is required, and proper application of temporary anchorage devices can significantly expand the scope of orthodontic treatment. Finally, treatment results are maintained by ongoing supportive periodontal therapy even during the retention period. CONCLUSIONS: This article presents clinical cases demonstrating the importance of accurate diagnosis in orthodontics and periodontics and the positive impact of orthodontic treatment on patients with pre-existing periodontal diseases. CLINICAL SIGNIFICANCE: An up-to-date orthodontic treatment protocol for periodontally compromised patients is presented.

Interdisciplinary treatment of mutilated dentition and transverse maxillary deficiency with microimplant-assisted rapid palatal expansion, microimplants, and dental implants.

OBJECTIVE: This case report demonstrates an interdisciplinary approach to treat a 26-year-old male patient with hyperdivergent Class II skeletal pattern, maxillary transverse deficiency, slight anterior open bite, and multiple hopeless teeth with root rests. CLINICAL CONSIDERATIONS: An interdisciplinary treatment was required for oral hygiene improvement, caries treatment, extraction of residual roots and hopeless teeth, maxillary expansion using microimplant-assisted rapid palatal expansion, improvement of skeletal and dental relationship using orthodontic microimplants, and prosthetic restorations with the aid of dental implants. CONCLUSION: Consequently, esthetic and functional occlusal rehabilitation was achieved. CLINICAL SIGNIFICANCE: Hyperdivergent Class II facial and skeletal patterns with multiple missing teeth can be effectively treated using orthodontic skeletal anchorage. In young adults, the transverse discrepancy can be resolved using MARPE, which is also useful for improving the sagittal and vertical relationships. In the case of multiple missing teeth, orthodontic treatment can provide the proper space to facilitate dental implants to achieve optimal esthetics and function.

Digital application of three-dimensional diagnosis and treatment with a virtual articulator.

OBJECTIVE: The purpose of this article was to introduce a method for the digital application of three-dimensional (3D) diagnosis and treatment with a virtual articulator and 3D data. CLINICAL CONSIDERATION: With the use of cone-beam computed tomography (CBCT) and intraoral and facial scans, we can create a virtual articulator and evaluate the mandibular position in maximum intercuspation and centric-related occlusion for the patient with an unstable occlusion and temporomandibular disorders (TMD). Based on this, we treated a case using a digital mandibular position indicator (MPI) and fabricated a stabilization splint using a 3D printer. This approach eliminates the traditional impression or model mounting process and the analog face bow transfer. Furthermore, the design of the stabilization splint is accomplished using software. CONCLUSIONS: The approach outlined in this article offers the potential for a digital diagnosis and treatment process by seamlessly integrating CBCT, intraoral scans, and facial scans with a high degree of accuracy. This may enhance precision in diagnosis and treatment planning, especially for patients with complicated TMD, in addition to facilitating effective communication with orthodontic patients who require thorough attention. CLINICAL SIGNIFICANCE: Utilizing a virtual articulator and digital MPI for the occlusal evaluation of patients with TMD and unstable occlusion makes it possible to diagnose and analyze the occlusal condition accurately. This approach also allows for precision and efficiency in treatment.

Surgical vs nonsurgical treatments in patients with anterior open-bite have similar effects in occlusal function: A 2-year follow-up study.

INTRODUCTION: This study aimed to investigate changes in bite force (BF) and occlusal contact area after anterior open-bite (AOB) treatment and compare the changes in surgical vs nonsurgical treatment. METHODS: This retrospective study included patients with AOB compared with normal occlusion. AOB was corrected by either intrusion of the maxillary molars (intrusion group, n = 19) or orthognathic surgery (surgery group, n = 37). The control group (n = 35) had a normal overbite relationship. Records of lateral cephalograms, BF, and occlusal contact area taken before (T0), immediately after (T1), and 2 years after (T2) orthodontic treatment were compared within and among the 3 groups. RESULTS: The open-bite group, including intrusion and surgery groups, had a lower BF and less occlusal contact area than the control group at T0 and T1 (P <0.001). However, there were no significant differences among the 3 groups at T2 (P >0.05). The intrusion and surgery groups showed no significant differences throughout the observation period extending from T0 to T2 (P >0.05). Although BF and occlusal contact area decreased at T1 compared with T0, they increased during retention and showed higher values at T2 than at T0. CONCLUSIONS: Treatment of AOB improved BF and occlusal contact area 2 years posttreatment. Orthognathic surgery and molar intrusion using orthodontic miniscrews can improve occlusal function similarly. Orthodontists can select either method depending on malocclusion severity and patient demand.

2023-2024 American Board of Orthodontics practice analysis study: Part 1.

As a specialty board, the American Board of Orthodontics (ABO) serves to protect the public and the orthodontic specialty by certifying orthodontists. The demonstration of commitment to lifelong learning and self-improvement is critical to achieving the highest level of patient care. The ABO completed a practice analysis study in 2023 to ensure all examinations represent current assessments of proficiency in orthodontics at a level of quality that satisfies professional expectations. The practice analysis is essential to providing a demonstrable relationship between the examination content and orthodontic practice and provides a critical foundation for ABO's examination programs.

Evaluation of modified C-palatal plates on speech articulation using acoustic analysis.

INTRODUCTION: The purpose of this study was to assess speech perturbation and adaptation for patients wearing modified C-palatal plates (MCPPs) over time. METHODS: The sample consisted of 40 patients, 20 wearing MCPPs as the experimental group (age: 20.7 ± 5.8 years) and 20 patients wearing a transpalatal arch (TPA) as the control group (age: 21.5 ± 6.4 years). The sounds /t/, /d/, /s/, /n/, /r/, /tʃ/. and /j/ were recorded for each patient at six time points: immediately before (T0) and after (T1) appliance placement; then 1, 2, 3 and 4 weeks after placement (T2-T5). Acoustic analysis of pitch and voice onset time (VOT) was performed by Praat software. Repeated measures analysis of variance (RM-ANOVA) was used to assess changes in the pitch and VOT over time and the difference between the appliances. RESULTS: With the MCPP appliance, /n/, /r/, /tʃ/ and /j/ decreased in VOT starting in the first week while /t/ and /s/ almost returned to pre-treatment levels after 2 weeks. VOT for the /d/ sound did not change between T0 and T3, but it decreased after 3 weeks. There were no significant differences in pitch and VOT between the two groups at any time point. CONCLUSIONS: Wearing an MCPP device caused patients to initially distort the articulation of several sounds, but the distortion dissipated within 1 to 2 weeks. It is recommended that patients and/or their parents be advised during pre-treatment counselling of the possibility of temporary speech changes with MCPP placement.

Rare Congenital Frontal Hairline Deformity with Temporo-Parieto-Occipital Multiple Folds of Scalp.

Two cases of congenital hairline deformity are reported. Both cases exhibited multiple wrinkled areas in the lower occipital region, with hair that punctured and irritated the adjacent skin as it grew, creating ulcerated lesions. Both patients had a unilateral folded and raised wrinkled and twisted region stretching from the temporal area to the parietal and occipital areas. There was also a defect in the frontotemporal hairline of the affected side that was not present on the contralateral side. The skin of the forehead was also thinner on the affected side. Both patients were in good physical health and had no other congenital abnormalities or pertinent family history. There were no other skin, neurological, or physical abnormalities. In each case, the excessive skin was excised from the temporo-occipital region and microscopically dissected into follicular units, which were transplanted into the temporal area and the frontal hairline. Histologic examination did not reveal any specific abnormal findings. The transplanted hairs were well engrafted and showed natural results. Congenital anomalies of the hairline or hair-bearing scalp tissue are rare. Cutis verticis gyrata is a rare disease that causes multiple furrows and folds of the scalp. However, the cases reported here exhibited a somewhat different appearance from that of cutis verticis gyrata, as multiple folds were present in the scalp in each case, along with an alopecic lesion. This author has successfully treated 2 cases of this rare form of congenital hair loss that has not yet been reported to our knowledge.

A Simultaneous Pipe-Attribute and PIG-Pose Estimation (SPPE) Using 3-D Point Cloud in Compressible Gas Pipelines.

An accurate estimation of pipe attributes, pose of pipeline inspection gauge (PIG), and downstream pipeline topology is essential for successful in-line inspection (ILI) of underground compressible gas pipelines. Taking a 3D point cloud of light detection and ranging (LiDAR) or time-of-flight (ToF) camera as the input, in this paper, we present the simultaneous pipe-attribute and PIG-pose estimation (SPPE) approach that estimates the optimal pipe-attribute and PIG-pose parameters to transform a 3D point cloud onto the inner pipe wall surface: major- and minor-axis lengths, roll, pitch, and yaw angles, and 2D deviation from the center of the pipe. Since the 3D point cloud has all spatial information of the inner pipe wall measurements, this estimation problem can be modeled by an optimal transformation matrix estimation problem from a PIG sensor frame to the global pipe frame. The basic idea of our SPPE approach is to decompose this transformation into two sub-transformations: The first transformation is formulated as a non-linear optimization problem whose solution is iteratively updated by the Levenberg-Marquardt algorithm (LMA). The second transformation utilizes the gravity vector to calculate the ovality angle between the geometric and navigation pipe frames. The extensive simulation results from our PIG simulator based on the robot operating system (ROS) platform demonstrate that the proposed SPPE can estimate the pipe attributes and PIG pose with excellent accuracy and is also applicable to real-time and post-processing non-destructive testing (NDT) applications thanks to its high computational efficiency.

Depression and its associated factors: A comparison between congenital and acquired physical disabilities.

OBJECTIVE: While depression associated with disability has been extensively studied, how depression could differ depending on whether the disability is congenital or acquired remains to be investigated. The objective of this study was to compare depression and its related factors among people with congenital and acquired physical disabilities. METHODS: We used the 2016 Panel Survey of Employment for the Disabled in Korea, a population-based survey for people with disability registered with the Korean government. Among 4577 participants, a total of 2128 participants with physical disability were analyzed using Chi-square test and binary logistic regression analysis. RESULTS: The prevalence of depression was 12.9% in those with congenital physical disability and 16.0% in those with acquired physical disability. Stress due to disability and family relationship satisfaction were associated with higher and lower odds of depression, respectively, in both disability groups. Discrimination due to disability, divorce, social participation, and subjective social status were significant predictors of depression only in people with acquired disability. CONCLUSIONS: Compared to those with congenital disability, individuals with acquired disability can be more susceptible to issues relating to social relationship, social standing and discrimination. Findings of this study suggest that acquired disability and adapting to changes associated with it can be a source of mental distress in addition to living with it. More efforts are needed to address discrimination, provide supportive social relationships, and provide supportive living conditions in order to reduce depression in persons living with disability, especially those with acquired disability.

A 3-dimensional evaluation of available retromolar space for the application of ramal plates.

INTRODUCTION: This study aimed to evaluate the available retromolar space for ramal plates in patients with Class I and III malocclusions and compare that space with and without third molars using cone-beam computed tomography. METHODS: Cone-beam computed tomography images of 30 patients (17 males, 13 females; mean age, 22.2 ± 4.5 years) with Class III malocclusion and 29 subjects (18 males, 11 females; mean age, 24.3 ± 3.7 years) with Class I malocclusion were analyzed. Available retromolar space at 4 axial levels of the second molar root and the volume of the retromolar bone were evaluated. Two-way repeated measures analysis of covariance (repeated measures analysis of covariance) was applied to compare the variables between Class I and III malocclusions and the presence of third molars. RESULTS: Patients with Class I and III relationships showed up to 12.7 mm of available retromolar space at 2 mm apical from the cementoenamel junction (CEJ). At 8 mm apical from CEJ, patients with Class III malocclusion had 11.1 mm of space, whereas those with a Class I relationship showed 9.8 mm of available space. When patients had third molars, the amount of available retromolar space was significantly greater in patients with a Class I and III relationship. However, patients with Class III malocclusion exhibited greater available retromolar space than those with a Class I relationship (P = 0.028). In addition, the bone volume was significantly greater in patients with Class III malocclusion than in patients with a Class I relationship and those with third molars than in those without them (P <0.001). CONCLUSIONS: Class I and III groups showed the availability of at least 10.0 mm of retromolar space 2 mm apical to the CEJ for molar distalization. Based on this information, it is suggested that clinicians consider available retromolar space for molar distalization in diagnosing and planning treatment for patients with Class I and III malocclusion.