Does curve of Spee affect the precision of 3D-printed curvature-adaptive splints?

OBJECTIVES: This study aimed to propose a standardized protocol for the fabrication of three-dimensionally (3D)-printed curvature-adaptive splints (CASs) and assess the precision of CASs on dentitions with different depths of the curve of Spee (COS). METHODS: 76 lower dental resin models, each exhibiting one of the four types of COS (0-, 2-, 4-, and 6-mm deep), were selected and digitally scanned. CASs were designed, 3D printed, and grouped into C0, C2, C4, and C6, corresponding to the four types of COS depths. To assess precision, the CASs occluded with the resin model were scanned as a whole and compared with the originally designed ones. RESULTS: In terms of translational deviations observed in the CASs, the mean value of absolute sagittal deviation (0.136mm) was significantly higher than those of vertical (0.091mm) and transversal deviations (0.045mm) (P < 0.01). Regarding rotational deviations of the CASs, the mean deviation in pitch (0.323°) was significantly higher than those in yaw (0.083°) and roll (0.110°) (P < 0.01). However, when comparing the accuracy of CASs across C0, C2, C4, and C6 groups, no statistically significant difference was found. Additionally, the translational deviations, rotational deviations, and RMSE of all groups were significantly lower than the clinically acceptable limits of 0.5mm, 1°, and 0.25mm, respectively (P<0.01). CONCLUSIONS: The depth of the COS has no significant impact on the precision of CASs, as evidenced by the absence of statistically significant differences in translational, rotational deviations, and RMSE among all groups (C0, C2, C4, and C6). Moreover, despite relatively high deviations in the sagittal dimension and pitch, all dimensional deviations and RMSE remained statistically significantly lower than the corresponding clinically acceptable limits (CALs) in all groups. CLINICAL SIGNIFICANCE: This standardized protocol incorporating "curvature-adaptation" represents an optimized approach to fabricating diverse 3D-printed splints tailored to dentitions with different anatomical features in contemporary digital dentistry.

Does clinical experience affect the bracket bonding accuracy of guided bonding devices in vitro?

OBJECTIVES: To study whether and how the clinical experience of the operator affects the accuracy of bracket placement using guided bonding devices (GBDs) in vitro. MATERIALS AND METHODS: Five resin models were bonded virtually with brackets, and the corresponding GBDs were generated and three-dimensionally printed. Nine operators, which included three dental students, three orthodontic students, and three orthodontists, bonded the brackets on the resin models using GBDs on a dental mannequin. After being bonded with brackets, the models were scanned, and the actual and designed positions of the brackets were compared. RESULTS: There was no immediate debonding. The orthodontists spent a significantly shorter time (22.36 minutes) in bracket bonding than the dental students (24.62 minutes; P < .05). The brackets tended to deviate to the buccal side in the dental student group. Linear deviations tended to be smallest in the orthodontic student group, but no significant difference was found among operators with different clinical experience (P > .5). All linear and angular deviations in each group were under 0.5 mm and 2°, respectively. CONCLUSIONS: Clinical experience was positively related to the bonding accuracy using GBDs, especially in the buccolingual dimension. Inexperience also led to longer bonding duration. However, bonding accuracy was clinically acceptable in general.

Customized planning of the visible maxillary arch width in harmony with interparopia width and smile width for female facial aesthetics.

BACKGROUND: The visible maxillary arch width (VAW) is an important aesthetic-determining feature. To date, there is no well-established methodology to determine the aesthetically optimal VAW in customized treatment planning. METHODS: In this study, the common traits of the dentofacial configuration were investigated in most attractive Asian and Caucasian female smiles. The smiling photo of a subject was digitally modified based on combined variations of VAW, smile width (SW), transverse facial dimensions (TFD), and vertical facial dimensions. These modified photos were assessed for aesthetics. The aesthetically essential parameters were identified, and their mathematic correlations and reference ranges were determined for different vertical facial patterns. Using the obtained results, a mathematic guidance was constructed for customized smile designing. The applicability of this guidance was tested in Asian females. RESULTS: The most attractive Asian and Caucasian female smiles have intraracial and interracial commonalities in the VAW-to-TFD ratios. The interparopia width (IPD) predominated over facial widths in determining well-matched VAW and SW. For optimal smile aesthetics, the VAW and SW were correlated as simulated by the formula 1.92 IPD ≤ VAW + 2.3 SW ≤ 2.17 IPD, plus the VAW-to-IPD ratio within 0.54 to 0.62 and the SW-to-IPD ratio within 0.61 to 0.71, ranges tailored to vertical facial patterns. This constitutes a mathematic guidance for customized planning of the aesthetically optimal VAW. This guidance was preliminarily validated to be applicable to Asian females. CONCLUSIONS: The VAW-to-TFD ratios were essential for Caucasian and Asian female smile aesthetics. The mathematic guidance could serve as a reference for customized smile designs for Asian females.

Optimal settings for different tooth types in the virtual bracket removal technique.

OBJECTIVES: To determine the optimal settings for reconstructing the buccal surfaces of different tooth types using the virtual bracket removal (VBR) technique. MATERIALS AND METHODS: Ten postbonded digital dentitions (with their original prebonded dentitions) were enrolled. The VBR protocol was carried out under five settings from three commonly used computer-aided design (CAD) systems: OrthoAnalyzer (O); Meshmixer (M); and curvature (G2), tangent (G1), and flat (G0) from Geomagic Studio. The root mean squares (RMSs) between the reconstructed and prebonded dentitions were calculated for each tooth and compared with the clinically acceptable limit (CAL) of 0.10 mm. RESULTS: The overall prevalences of RMSs below the CAL were 66.80%, 70.08%, 62.30%, 94.83%, and 56.15% under O, M, G2, G1, and G0, respectively. For the upper dentition, the mean RMSs were significantly lower than the CAL for all tooth types under G1 and upper incisors and canines under M and G2. For the lower dentition, the mean RMSs were significantly lower than the CAL for all tooth types under G1 and lower incisors and canines under M, G2, and G0 (all P < .05). Additionally, the mean RMSs of all teeth under G1 were significantly lower than those under the other settings (all P < .001). CONCLUSIONS: The optimal settings varied among different tooth types. G1 performed best for most tooth types compared to the other four settings.

Effect of offset on the precision of 3D-printed orthognathic surgical splints.

OBJECTIVE: This study evaluated the effect of offset on the precision of three-dimensional (3D)-printed splints, proposing to optimize the splint design to compensate for systematic errors. MATERIALS AND METHODS: 14 resin model sets were scanned and offset as a whole by given distances (0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40 mm). Intermediate splints (ISs) and final splints (FSs) were generated from the non-offset and offset models and grouped correspondingly, named as splint type-offset value, IS-0.05, for instance. Dentitions occluded with the splint were scanned. Translational and rotational deviations of the lower dentition relative to the upper dentition were 3D measured. RESULTS: Deviations of ISs and FSs were more evident in the vertical and pitch dimensions, and were mostly acceptable in other dimensions. ISs with offset ≥ 0.05 mm showed vertical deviations significantly below 1 mm (P < 0.05) while ISs with 0.10- to 0.30-mm offsets had pitch rotations significantly lower than 1° (P < 0.05). The Pitch of IS-0.35 was significantly larger than ISs with 0.15- to 0.30-mm offsets (P < 0.05). Meanwhile, FSs fit better as the offset increased and FSs with offsets ≥ 0.15 mm all had deviations significantly lower than 1 mm (for translation) or 1° (for rotation) (P < 0.05). CONCLUSIONS: Offset affects the precision of 3D-printed splints. Moderate offset values of 0.10 to 0.30 mm are recommendable for ISs. Offset values ≥ 0.15 mm are recommended for FSs in cases with stable final occlusion. CLINICAL RELEVANCE: This study found the optimal offset ranges for 3D-printed ISs and FSs via a standardized protocol.

Comparison of bracket bonding between two CAD/CAM guided bonding devices: GBD-U vs GBD-B.

OBJECTIVE: To compare the bracket bonding accuracy, efficiency, reproducibility, and three-dimensional (3D) printing duration of the computer-aided design/computer-aided manufacturing (CAD/CAM) unilateral contact guided bonding device (GBD-U) and the bilateral contact guided bonding device (GBD-B) in vitro. METHODS: Five resin dental model sets were scanned and virtually bonded with brackets. GBD-U and GBD-B were designed and 3D printed for each model. GBD-Us had guide blocks that fit the occlusal sides of the bracket tie-wings, while GBD-Bs had guide arms that fit the occlusal and distal sides of the tie-wings. Five orthodontic residents were recruited to bond brackets on the same 3D-printed copies of resin models in a dental mannequin using GBD-Us and GBD-Bs, respectively. The time for 3D printing of GBDs and bracket bonding was recorded. The linear and angular deviations between the bonded brackets and the virtually bonded ones were measured. RESULTS: A total of 50 sets of resin models (1000 brackets/tubes) were bonded. The time for 3D printing and bracket bonding was shorter for GBD-Us (41.96 mins/6.38 mins) than for GBD-Bs (78.04 mins/7.20 mins). In both devices, 100% linear deviations and over 95% angular deviations were below 0.5 mm or 2°, respectively. Deviations in the mesiodistal dimension, torque, angulation, and rotation were significantly lower in the GBD-U group (P<0.01). High inter-operator reproducibility of bracket bonding was confirmed for both devices. CONCLUSION: GBD-U was more time-efficient in 3D printing. Both GBDs showed clinically acceptable accuracy, whereas GBD-U had higher bonding accuracy in the mesiodistal dimension, torque, angulation, and rotation than GBD-B. CLINICAL SIGNIFICANCE: CAD/CAM GBD-U provides high bracket bonding accuracy in a time-efficient manner and has the potential to be clinically applied.

A coupled-lines system to determine the anteroposterior position of maxillary central incisors for smiling profile esthetics.

OBJECTIVES: To develop a coupled-lines system to determine the anteroposterior position of maxillary central incisors (U1) for smiling profile esthetics. MATERIALS AND METHODS: Thirty Asian females with ordinary and good facial harmony were selected as the study sample and the control sample, respectively. Three-dimensional facial images and 45°- and 90°-angled profiles were collected. The anteroposterior relationships between U1 and upper- and mid-facial soft tissue landmarks were measured. By morphing photos of the study sample, two artificial images were created to represent the well-balanced 45°- and 90°-angled profiles and were further processed with combined variations of soft tissue subnasale (SSn)-Glabella and the mid-point of facial axial points of the bilateral central incisor (mFA)-SSn distances. Esthetic assessments were performed on these images by layperson (n = 94) and orthodontist (n = 94) raters. RESULTS: Both upper- and mid-facial soft tissue landmarks were indispensable in assessing anteroposterior positions of U1 for well-balanced smiling profiles. As assessed in 45°- and 90°-angled profiles, the most esthetically sensitive parameters were mFA-Glabella and mFA-SSn distances. A coupled-lines system was constructed, comprising the Glabella and SSn vertical lines. In smiling profiles with optimal esthetics, the mFA point was at 2 to 5 mm posterior to the Glabella vertical and concomitantly 4 to 7 mm posterior to the SSn vertical, as perceived by orthodontists. Laypersons gave a wider range for mFA-Glabella distances, at 2 to 6 mm. CONCLUSIONS: The coupled-lines system could serve as a reliable reference for determining esthetically optimal anteroposterior positions of U1 for female facial profiles.

Research progress on deep learning algorithms to assist 3D tooth segmentation of digital dental models / 口腔疾病防治

@#Three-dimensional tooth segmentation is the segmentation of single-tooth models from a digital dental model. It is an important foundation for diagnosis, planning, treatment and customized appliance manufacturing in digital orthodontics. With the deep integration of artificial intelligence technology and big data from stomatology, the use of deep learning algorithms to assist 3D tooth segmentation has gradually become mainstream. This review summarizes the current situation of deep learning algorithms that assist 3D tooth segmentation from the aspects of dataset establishment, algorithm architecture, algorithm performance, innovation and advantages, deficiencies of current research and prospects. The results of the literature review showed that deep learning tooth segmentation methods could obtain an accuracy of more than 95% and had good robustness. However, the segmentation of complex dental models, operation time and richness of the training database still need to be improved. Research and development of the "consumption reduction and strong core" algorithm, establishment of an authoritative data sample base with multiple centers, and expansion of data application depth and breadth will lead to further development in this field.

Effects of offset design on the accuracy of bracket placement with a guided bonding device.

BACKGROUND: This study aimed to evaluate the effects of offset design on the accuracy of bracket placement for computer-aided design and computer-aided manufacturing (CAD/CAM)-guided bonding devices (GBDs) in vitro. METHODS: Eight dental models were selected. Seven types of GBDs were designed and three-dimensionally (3D) printed for each model, including one without any offset and the other six with translation offsets (TF) and expansion offsets (EF) of 0.05, 0.10, and 0.15 mm, respectively. After the brackets were bonded on the models using the different GBDs in vitro, linear and angular deviations of the bracket positions were evaluated. RESULTS: In total, 56 GBDs were printed, and 784 brackets were bonded using the GBDs. No misfit between the dentitions and the devices was found during the bonding process. With increasing offset, more brackets were gingivally positioned with the frequencies ranging from 61.61 to 76.79% for the TF groups and from 58.93 to 78.57% for the EF groups. The vertical deviations of the brackets increased from 0.100 to 0.168 mm and from 0.117 to 0.150 mm in the TF and the EF group, respectively, as offset increased. No statistically significant difference was found in the vertical deviation between most of the TF and EF groups with the same offset value (p > 0.05). With respect to angulation, the mean absolute deviations were 0.881, 1.083, and 1.029° in the 0.05-mm, 0.10-mm, and 0.15-mm EF groups, respectively, which were greater than those in the corresponding TF groups (0.799, 0.847, and 0.806°). Similarly, with increasing offset, the mean absolute deviations for rotation in the EF groups (0.847, 0.998, and 1.138°) were greater than those in the TF groups (0.853, 0.946, and 0.896°). Compared with the 0.15-mm TF group, greater angulations (p < 0.05) and rotations (p < 0.01) were found in the 0.15-mm EF group. CONCLUSIONS: Offset designs influenced the precision of vertical bracket placement with GBDs. Due to the smaller deviations in angulation and rotation of bracket placement, TF is preferred over EF for GBDs. Moreover, the differences between TF and EF also need to be considered in the design of other dental CAD/CAM devices.

Integrating maxillary dentition and 3D facial photo using a modified CAD/CAM facebow.

BACKGROUND: Accurate integration of the dentitions with the face is essential in dental clinical practice. Here we introduce a noninvasive and efficient protocol to integrate the digitized maxillary dentition with the three-dimensional (3D) facial photo using a prefabricated modified computer-aided design/computer-aided manufacture (CAD/CAM) facebow. METHODS: To integrate the maxillary dentition with the 3D facial photo, the CAD/CAM facebow protocol was applied to 20 patients by taking a series of 3D facial photos in the clinic and integrating them in the laboratory. The integration accuracy of this protocol was compared with that of a valid 3D computed tomography (CT)-aided protocol concerning translational deviations of the landmarks representing maxillary incisors and maxillary first molars as well as the rotational deviation of the maxillary dentition. The intra- and inter-observer reproducibility was assessed, and the time of clinical operation and laboratory integration was recorded. RESULTS: This facebow-aided protocol generated 3D fused images with colored faces and high-resolution dentitions, and showed high reproducibility. Compared with the well-established CT-aided protocol, the translational deviations ranged from 0 to 1.196 mm, with mean values ranging from 0.134 to 0.444 mm, and a relatively high integration error was found in the vertical dimension (Z) with a mean ± standard deviation (SD) of 0.379 ± 0.282 mm. Meanwhile, the rotational deviations ranged from 0.020 to 0.930°, with mean values less than 1°, and the most evident deviation was seen in pitch rotation with a mean ± SD of 0.445 ± 0.262°. The workflow took 4.34 ± 0.19 min (mins) for clinical operation and 11.23 ± 0.29 min for laboratory integration. CONCLUSION: The present radiation-free protocol with the modified CAD/CAM facebow provided accurate and reproducible transfer of the digitized maxillary dentition to the 3D facial photo with high efficiency.

Effect of occlusal coverage depths on the precision of 3D-printed orthognathic surgical splints.

BACKGROUND: Precise orthognathic surgical splints are important in surgical-orthodontic treatment. This study aimed to propose a standardized protocol for three-dimensional (3D)-printed splints and assess the precision of splints with different occlusal coverage on the dentition (occlusal coverage depth, OCD), thus optimizing the design of 3D-printed splints to minimize the seemingly unavoidable systematic errors. METHODS: Resin models in optimal occlusion from 19 patients were selected and scanned. Intermediate splints (ISs) and final splints (FSs) with 2-mm, 3-mm, 4-mm, and 5-mm OCDs were fabricated and grouped as IS-2, IS-3, IS-4, IS-5, FS-2, FS-3, FS-4, and FS-5, respectively. The dentitions were occluded with each splint and scanned as a whole to compare with the original occlusion. Translational and rotational deviations of the lower dentition and translational deviations of the landmarks were measured. RESULTS: For vertical translation, the lower dentitions translated inferiorly to the upper dentition in most of the splints, and the translation increased as OCD got larger. Vertical translations of the dentitions in 89.47% of IS-2, 68.42% of IS-3, 42.11% of IS-4, 10.53% of IS-5, 94.74% of FS-2, 63.16% of FS-3, 26.32% of FS-4, and 21.05% of FS-5 splints were below 1 mm, respectively. For pitch rotation, the lower dentitions rotated inferiorly and posteriorly in most groups, and the rotation increased as OCD got larger. Pitch rotations of the dentitions in 100% of IS-2, 89.47% of IS-3, 57.89% of IS-4, 52.63% of IS-5, 100.00% of FS-2, 78.95% of FS-3, 52.63% of FS-4, and 47.37% of FS-5 splints were below 2°, respectively. On the other hand, the transversal and sagittal translations, roll and yaw rotations of most groups were clinically acceptable (translation < 1 mm and rotation < 2°). The deviations of ISs and FSs showed no statistical significance at all levels of coverage (P > 0.05). CONCLUSIONS: A protocol was proposed to generate 3D-printed ISs and FSs with normalized basal planes and standardized OCDs. Deviations of the ISs and FSs were more evident in the vertical dimension and pitch rotation and had a tendency to increase as the OCD got larger. ISs and FSs with both 2-mm and 3-mm OCD are recommendable regarding the precision relative to clinical acceptability. However, considering the fabrication, structural stability, and clinical application, ISs and FSs with 3-mm OCD are recommended for accurate fitting.

Research progress on root position measurement methods in orthodontic treatment using cone beam CT / 口腔疾病防治

@#Root position plays an important role in healthy, stable, and aesthetic orthodontic treatment. In the past, two-dimensional radiographic images were used to assess the accuracy and precision of tooth root positions. In recent years, the use of cone beam CT (CBCT) and its reconstructed images to measure the three-dimensional spatial position and angle of root position has become mainstream. The root position is mainly described by measuring the relationship between the root and adjacent structures in the buccolingual, vertical, and mesiodistal directions as well as the root angle. The thickness of the alveolar bone on the buccolingual side of the root represents the buccolingual position, the vertical height in the alveolar bone and the relationship between apex and maxillary sinus represents the vertical position, the interroot alveolar bone thickness represents the mesiodistal position of the root, and the root angle is mostly based on incisal mandibular plane angle, angulation, torque, and other angles in the traditional two-dimensional measurement. Fitting CBCT and digital model data can be used to monitor the relationship between root and alveolar bone during orthodontic treatment, but a more comprehensive, standardized three-dimensional tooth root position measurement method is required to make full use of the root data provided by CBCT to study the relative optimal position of the tooth root at different anatomical levels, which combines with computer technology to optimize the digital design of orthodontic diagnosis and treatment.

Progress on application of artificial intelligence technology in orthodontic diagnosis and treatment / 口腔疾病防治

@#In recent years, artificial intelligence technology has developed rapidly and has been gradually applied to the fields of clinical image data processing, auxiliary diagnosis and prognosis evaluation. Research has shown that it can simplify doctors’ clinical tasks, quickly provide analysis and processing results, and has high accuracy. In terms of orthodontic diagnosis and treatment, artificial intelligence can assist in the rapid fixation of two-dimensional and three-dimensional cephalometric measurements. In addition, it is also widely used in the efficient processing and analysis of three-dimensional dental molds data, and shows considerable advantages in determining deciding whether orthodontic treatment needs tooth extraction, thus assisting in judging the stage of growth and development, orthodontic prognosis and aesthetic evaluation. Although the application of artificial intelligence technology is limited by the quantity and quality of training data, combining it with orthodontic clinical diagnosis and treatment can provide faster and more effective analysis and diagnosis and support more accurate diagnosis and treatment decisions. This paper reviews the current application of artificial intelligence technology in orthodontic diagnosis and treatment in the hope that orthodontists can rationally treat and use artificial intelligence technology in the clinic, and make artificial intelligence better serve orthodontic clinical diagnosis and treatment, so as to promote the further development of intelligent orthodontic diagnosis and treatment processes.

Relaxed 3D genome conformation facilitates the pluripotent to totipotent-like state transition in embryonic stem cells.

The 3D genome organization is crucial for gene regulation. Although recent studies have revealed a uniquely relaxed genome conformation in totipotent early blastomeres of both fertilized and cloned embryos, how weakened higher-order chromatin structure is functionally linked to totipotency acquisition remains elusive. Using low-input Hi-C, ATAC-seq and ChIP-seq, we systematically examined the dynamics of 3D genome and epigenome during pluripotent to totipotent-like state transition in mouse embryonic stem cells (ESCs). The spontaneously converted 2-cell-embryo-like cells (2CLCs) exhibited more relaxed chromatin architecture compared to ESCs, including global weakening of both enhancer-promoter interactions and TAD insulation. While the former correlated with inactivation of ESC enhancers and down-regulation of pluripotent genes, the latter might facilitate contacts between the putative new enhancers arising in 2CLCs and neighboring 2C genes. Importantly, disruption of chromatin organization by depleting CTCF or the cohesin complex promoted the ESC to 2CLC transition. Our results thus establish a critical role of 3D genome organization in totipotency acquisition.

Three-dimensional surgical guide approach to correcting skeletal Class II malocclusion with idiopathic condylar resorption.

Treatment of skeletal Class II patients with dual bite and idiopathic condylar resorption (ICR) is challenging for orthodontists because of the unstable position of the mandible as well as skeletal relapse attributed to improper seating of the mandibular condyles. This case report describes the successful treatment of an 18-year-old Mongolian man diagnosed with centric relation-maximum intercuspation discrepancy and ICR. After making a definitive diagnosis from verified centric relation using bilateral manipulation, orthodontic treatment was initiated followed by three-dimensional computer-aided design/computer-aided manufacturing prebent titanium plate-guided sagittal split ramus osteotomy and genioplasty. Postoperative 3D superimposition demonstrated that this surgical guide approach provided accurate repositioning of the condyles, which were well positioned in the fossae. Complete orthodontic and surgical treatment time was 24 months. The patient's facial appearance and occlusion improved significantly, and a stable result was obtained with a 1-year follow-up.

Accurate bracket placement using a computer-aided design and computer-aided manufacturing-guided bonding device: An in vivo study.

INTRODUCTION: A protocol was introduced to achieve accurate bracket placement in vivo, which consisted of operative procedures for precise control, and a computer-aided design and computer-aided manufacturing-guided bonding device. To evaluate the accuracy of this protocol, a 3-dimensional assessment was performed. METHODS: Ten consecutive patients were enrolled. Strictly following the protocol, from December 2017 to March 2018, brackets were placed on the teeth of each patient using the device. To evaluate the accuracy, deviations of positions and orientations for bracket placement were measured. Each patient was followed up after 3 months regarding bracket failures. RESULTS: The guided bonding device was used in all cases, and a total of 205 brackets were successfully bonded and evaluated. Except for 15.12% brackets with torque deviation over 2°, the deviations in mesiodistal, buccolingual, vertical, rotation, and angulation were below the clinical acceptable range (0.5 mm in translation or 2° in orientation) for all brackets. In the 3-month follow-up, there was no bracket failure in any patient. CONCLUSION: This protocol transferred the planned bracket position from the digital setup to patient's dentition with generally high positional accuracy.

SOST Deficiency Aggravates Osteoarthritis in Mice by Promoting Sclerosis of Subchondral Bone.

As the initial part in the development of osteoarthritis (OA), subchondral bone sclerosis has been considered to be initiated by excess mechanical loading and proven to be correlated to other pathological changes. Sclerostin, which is an essential mechanical stress response protein, is encoded by the SOST gene. It is expressed in osteocytes and mature chondrocytes and has been proven to be closely correlated to OA. However, the relationship and mechanism between the SOST gene and the development of OA remain unclear. The aim of the present study was to investigate the role of the SOST gene in OA pathogenesis in the subchondral bone. A knee anterior cruciate ligament transection (ACLT) mouse osteoarthritis (OA) model on SOST-knockout (SOST KO) and wild-type (WT) mice was established. The pathogenic and phenotypic changes in the subchondral bone were investigated by histology, micro-CT, immunohistochemistry, TRAP staining, Masson staining, and Toluidine blue staining. It was found that sclerostin expression decreased in both the calcified cartilage and mineralized subchondral structures during the development of OA. Joint instability induced a severe cartilage degradation phenotype, with higher OARSI scores in SOST KO mice, when compared to WT mice. SOST KO mice with OA exhibited a higher BMD and BV/TV ratio, as well as a higher rate of bone remodeling and TRAP-positive cell number, when compared to the WT counterparts, but the difference was not significant between the sham-operation groups. It was concluded that loss of sclerostin aggravates knee OA in mice by promoting subchondral bone sclerosis and increasing catabolic activity of cartilage.

Full-Arch Implant-Supported Rehabilitation Guided by a Predicted Lateral Profile of Soft Tissue.

In full-arch implant-supported rehabilitation of patients with severe periodontitis, prediction of lateral facial profile with modified dental position remains a challenge, especially for patients with protruded anterior teeth. This clinical report describes a digital workflow to predict lateral profiles and then guide the implant placement and restoration fabrication.

Periodontal ligament fibroblasts regulate osteoblasts by exosome secretion induced by inflammatory stimuli.

OBJECTIVES: This study evaluated the role of human periodontal ligament fibroblasts (hPDLFs)-derived exosomes in periodontitis progression and discovered whether hPDLFs influence bone remodeling activity via exosome secretion. MATERIALS AND METHODS: Exosomes were isolated and quantified from Porphyromonas gingivalis lipopolysaccharide (LPS)-treated primary hPDLFs and evaluated by western blotting, dynamic light scattering, and transmission electron microscopy. GW4869 was used to block exosome secretion in conditioned medium (CM). hPDLFs-derived CM, CM containing GW4869 (CM + GW4869) and exosomes were used to stimulate MG-63 cell lines. The expression levels of proinflammatory mediators, osteogenic genes, and osteoclastogenesis-related genes were measured by quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, and alkaline phosphatase staining. RESULTS: Exosome-enriched protein and total exosomal protein levels were higher in the LPS-treated group than in the vehicle controls. hPDLFs-derived exosomes were incorporated into MG-63 osteoblasts and slightly upregulated the expression of Interleukin-6 and tumor necrosis factor-alpha. CM and exosomes inhibited alkaline phosphatase, Collagen-I, Runt-related transcription factor 2, and Osteoprotegerin expression as well as ALP activity, and blocking exosome secretion by GW4869 eliminated the inhibitory effects. CONCLUSION: These results indicate that LPS-pretreated hPDLFs induce inflammation and inhibit osteogenic activity of osteoblasts through secreting exosomes. This study provides a potential mechanism by which localized periodontal inflammation may influence bone remodeling by release exosomes.