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Background/purpose The measurement of mandibular kinematics is critical for studying the function of the temporomandibular joint (TMJ) and for relevant clinical applications. However, none of the existing methods allows the measurement of three-dimensional (3D) in vivo motion of the joint during dynamic functional movements without artifactual interference. The purpose of this study was to demonstrate the feasibility of a newly developed cone-beam computed tomography (CBCT)-based 3D fluoroscopic method in differentiating rigid-body kinematics of the TMJ during various functional activities. Materials and methods One healthy individual was asked to undergo a CBCT scan and fluoroscopic imaging of her mandible and maxilla during various functional activities. CBCT-based 3D fluoroscopy was used to measure the 3D kinematics of the TMJ. Results The 3D rigid-body kinematics of the mandible, movement trajectories of the centers of the TMJ and the midpoint of the interincisal edge were measured during functional activities. Conclusion A new CBCT-based 3D fluoroscopic method was proposed and shown to be capable of quantitatively differentiating TMJ movement patterns among complicated functional activities. It also enabled a complete description of the rigid-body mandibular motion and descriptions of as many reference points as needed for future clinical applications. It will be helpful for dental practice and for a better understanding of the functions of the TMJ.

Background/purpose Skin marker-based systems are used to accurately measure the three-dimensional motion of the temporomandibular joint. Since skin markers move relative to the underlying bone during jaw movements, the measured temporomandibular joint kinematics is subject to soft-tissue artifacts. A complete evaluation of soft-tissue artifacts for markers on the facial anatomical landmarks and on an optical frame during jaw opening/closing movements is not available. The purpose of this study was to further our knowledge using a commercial opto-electronic movement tracking system to measure marker movements, that were then compared to true values defined by a transoral rigid device attached to the incisors. Materials and methods Twenty healthy subjects performed jaw opening/closing movements at a self-selected pace while the 3D trajectories of 17 facial skin markers, three markers on an optical frame, and 4 markers on a transoral device were measured using a six-camera opto-electronic motion tracking system. Movements of the skin and optical frame markers relative to the head coordinate system defined by the transoral device (gold standard) were calculated. The movements of the head coordinate systems defined using different groups of skin markers relative to the gold standard were also analyzed. Results The results showed that nose-bridge markers had minimal displacements but the middle- and side-face markers had large displacements. Conclusions It appears that markers on the frontal nose bridge are good alternatives to transoral rigid devices for measuring mandibular motion, compared to optical frame markers and other skin markers on the face. The results of the current study will be helpful for establishing guidelines for marker placement when measuring mandibular movements in patients with potential temporomandibular disorders.

Obstructive sleep apnea (OSA), which is caused by obstructions of the upper airway, is a syndrome with rising prevalence. Mandibular advancement splints (MAS) are oral appliances for potential treatment of OSA. This work proposes a highly-sensitive pressure sensing array integrated with a system-on-chip (SoC) embedded in a MAS. The device aims to measure tongue pressure distribution in order to determine the efficacy of the MAS for treating OSA. The flexible sensing array consists of an interdigital electrode pair array assembled with conductive polymer films and an SoC capable of retrieving/storing data during sleep, and transmitting data for analysis after sleep monitoring. The surfaces of the conductive polymer films were patterned with microdomed structures, which effectively increased the sensitivity and reduced the pressure sensing response time. The measured results also show that the crosstalk effect between the sensing elements of the array was negligible. The sensitivity of the sensing array changed minimally after the device was submerged in water for up to 100 h.

The purpose of this study was to measure the long-term growth of the mandible in miniature pigs using 3D Cone-Beam Computerized Tomography (CBCT). The mandibles of the pigs were scanned monthly over 12 months using CBCT and the 3D mandibular models were reconstructed from the data. Seventeen anatomical landmarks were identified and classified into four groups of line segments, namely anteroposterior, superoinferior, mediolateral and anteroinferior. The inter-marker distances, inter-segmental angles, volume, monthly distance changes and percentage of changes were calculated to describe mandibular growth. The total changes of inter-marker distances were normalized to the initial values. All inter-marker distances increased over time, with the greatest mean normalized total changes in the superoinferior and anteroposterior groups (p0.05). Monthly distance changes were greatest during the first four months and then reduced over time. Percentages of inter-marker distance changes were similar among the groups, reaching half of the overall growth around the 4th month. The mandibular volume growth increased non-linearly with time, accelerating during the first five months and slowing during the remaining months. The growth of the mandible was found to be anisotropic and non-homogeneous within the bone and non-linear over time, with faster growth in the ramus than in the body. These growth patterns appeared to be related to the development of the dentition, providing necessary space for the teeth to grow upward for occlusion and for the posterior teeth to erupt.

Specimens of ductile irons austempered at 320 °C and 360 °C for 2 h were conducted with ultrasonic vibration treatment. Microstructures were characterized using optical (OM) and scanning electron microscopy (SEM) and X-ray diffraction. Vickers hardness was also measured to assess the variation of hardness affected by the microstructure. Experimental results show that specimens after cavitation erosion progressively developed phase transformation induced by plastic deformation. Some stringer-type austenite was found to precipitate carbides, while some island-like austenite was transformed into martensite. If the microstructure led to deplete carbon within the island-like austenite, this austenite readily transformed to martensite due to stress induced by microjet impact. If austenite was rich in Mn, the transformation from austenite to martensite would be retarded. The observations then indicate the coexistence of martensite and precipitated ferrite particles within the colony of island-like austenite. With increased cumulative ultrasonic time, microhardness values were enhanced both in areas near graphite and in intercellular regions. In addition, the elastic strain-energy density estimated from a microjet impact was lower than the theoretical value of homogeneous nucleation of martensite nucleus. Clearly, the transformed martensite was induced by heterogeneous nucleation.

Introduction This study aimed to determine the effect of combining positive airway pressure (PAP) therapy and mandibular advancement device (MAD) in patients with severe obstructive sleep apnea (OSA) who were pressure intolerant for PAP and were unresponsive to MAD. Methods This retrospective study reviewed the medical records of severe OSA patients with apnea-hypopnea index (AHI) ≥ 30/hr who were diagnosed between October 1, 2008 and June 30, 2014. Patients were initially treated with 2 weeks of PAP, and those who were intolerant to high-pressure PAP (≥15 cm H2O) were switched to 12 weeks of MAD, which is a monobloc designed at 75% of maximum protrusion. Patients who had high residual AHI (≥15/hr) on MAD underwent 12 weeks of combination therapy (CT) with MAD and CPAP and were enrolled in the present study. Enrolled subjects who completed the 12-week CT were followed-up until June 30, 2016. Results A total of 14 male patients were included. All three treatments effectively reduced AHI, oxygen desaturation index (ODI), and total sleep time with SpO2

Sleep apnea is a serious sleep disorder, and the most common type is obstructive sleep apnea (OSA). Untreated OSA will cause lots of potential health problems. Oral appliance therapy is an effective and popular approach for OSA treatment, but making a perfect fit for each patient is time-consuming and decreases its efficiency considerably. This paper proposes a System-on-a-Chip (SoC) enabled sleep monitoring system in a smart oral appliance, which is capable of intelligently collecting the physiological data about tongue movement through the whole therapy. A tunneling sensor array with an ultra-high sensitivity is incorporated to accurately detect the subtle pressure from the tongue. When the device is placed on the wireless platform, the temporary stored data will be retrieved and wirelessly transmitted to personal computers and cloud storages. The battery will be recharged by harvesting external RF power from the platform. A compact prototype module, whose size is 4.5 × 2.5 × 0.9 cm3, is implemented and embedded inside the oral appliance to demonstrate the tongue movement detection in continuous time frames. The functions of this design are verified by the presented measurement results. This design aims to increase efficiency and make it a total solution for OSA treatment.

Progressive narrowing of the upper airway increases airflow resistance and can produce snoring sounds and apnea/hypopnea events associated with sleep-disordered breathing due to airway collapse. Recent studies have shown that acoustic properties during snoring can be altered with anatomic changes at the site of obstruction. To evaluate the instantaneous association between acoustic features of snoring and the anatomic sites of obstruction, a novel method was developed and applied in nine patients to extract the snoring sounds during sleep while performing dynamic magnetic resonance imaging (MRI). The degree of airway narrowing during the snoring events was then quantified by the collapse index (ratio of airway diameter preceding and during the events) and correlated with the synchronized acoustic features. A total of 201 snoring events (102 pure retropalatal and 99 combined retropalatal and retroglossal events) were recorded, and the collapse index as well as the soft tissue vibration time were significantly different between pure retropalatal (collapse index, 24 ± 11%; vibration time, 0.2 ± 0.3 s) and combined (retropalatal and retroglossal) snores (collapse index, 13 ± 7% [P ≤ 0.0001]; vibration time, 1.2 ± 0.7 s [P ≤ 0.0001]). The synchronized dynamic MRI and acoustic recordings successfully characterized the sites of obstruction and established the dynamic relationship between the anatomic site of obstruction and snoring acoustics.

Background The current study aimed to compare the measurements of the mandible morphology using 3D cone beam computed tomography (CBCT) images with those using 2D CBCT-synthesized cephalograms; to quantify errors in measurements based on 2D synthesized cephalograms; and to clarify the effects such errors have on the description of the mandibular growth. Methods Mandibles of six miniature pigs were scanned monthly using CBCT over 12 months and the data were used to reconstruct the 3D bone models. Five anatomical landmarks were identified on each bone model, and the inter-marker distances and monthly distance changes were calculated and taken as the gold standard. Synthetic 2D cephalograms were also generated for each bone model using a digitally reconstructed radiography (DRR)-generation method. Errors in cephalogram measurements were determined as the differences between the calculated variables in cephalograms and the gold standard. The variations between cephalograms and the gold standard were also compared using paired t-tests. Results While the inter-marker distance increases varied among the marker pairs, all marker pairs increased their inter-marker distances gradually every month, reaching 50% of the total annual increases during the fourth and fifth months, and then slowing down in the subsequent months. The 2D measurements significantly underestimated most of the inter-marker distances throughout the monitoring period, in most of the monthly inter-marker distance changes during the first four months, and in the total growth (p

Obstructive sleep apnea syndrome (OSAS) is caused by multi-level upper airway obstruction. Anatomic changes at the sites of obstruction may modify the physical or acoustic properties of snores. The surgical success of OSA depends upon precise localization of obstructed levels. We present a case of OSAS who received simultaneous dynamic MRI and snore acoustic recordings. The synchronized image and acoustic information successfully characterize the sites of temporal obstruction during sleep-disordered breathing events.

The purpose of this study was to measure the long-term growth of the mandible in miniature pigs using 3D Cone-Beam Computerized Tomography (CBCT). The mandibles of the pigs were scanned monthly over 12 months using CBCT and the 3D mandibular models were reconstructed from the data. Seventeen anatomical landmarks were identified and classified into four groups of line segments, namely anteroposterior, superoinferior, mediolateral and anteroinferior. The inter-marker distances, inter-segmental angles, volume, monthly distance changes and percentage of changes were calculated to describe mandibular growth. The total changes of inter-marker distances were normalized to the initial values. All inter-marker distances increased over time, with the greatest mean normalized total changes in the superoinferior and anteroposterior groups (p

This study investigated whether the presence of tooth wear in young adults can help to discriminate patients with sleep bruxism (SB) from control subjects.The tooth wear clinical scores and frequency of sleep masseter electromyographic activity of 130 subjects (26.6 +/- 0.5 years) were compared in this case-control study. Tooth wear scores (collected during clinical examination) for the incisors, canines, and molars were pooled or analyzed separately for statistics. Sleep bruxers (SBrs) were divided into two subgroups according to moderate to high (M-H-SBr; n = 59) and low (L-SBr; n = 48) frequency of masseter muscle contractions. Control subjects (n = 23) had no history of tooth grinding. The sensitivity and specificity of tooth wear versus SB diagnosis, as well as positive and negative predictive values (PPV and NPV), were calculated. One-way analysis of variance and the Mann-Whitey U test were used to compare groups.Both SBr subgroups showed significantly higher tooth wear scores than the control group for both pooled and separated scores (P.001). No difference was observed between M-H-SBr and L-SBr frequency groups (P = .14). The pooled sum of tooth wear scores discriminates SBrs from controls (sensitivity = 94%, specificity = 87%). The tooth wear PPV for SB detection was modest (26% to 71%) but the NPV to exclude controls was high (94% to 99%).Although the presence of tooth wear discriminates SBrs with a current history of tooth grinding from nonbruxers in young adults, its diagnostic value is modest. Moreover, tooth wear does not help to discriminate the severity of SB. Caution is therefore mandatory for clinicians using tooth wear as an outcome for SB diagnosis.

Objective To assess the effects of epigallocatechin-3-gallate (EGCG) on oncostatin M (OSM)–induced CCL2 synthesis and the associated signaling pathways in human osteoblastic cells. The therapeutic effect of EGCG on collagen-induced arthritis (CIA) in rats was also studied. Methods CCL2 and c-Fos messenger RNA expression was analyzed by Northern blotting. The modulating effects of EGCG on the activation of Raf-1, Akt, and phosphatidylinositol 3-kinase (PI 3-kinase) were examined by coimmunoprecipitation, Western blotting, and PI 3-kinase activity assay. Interactions between c-Fos and CCL2 promoter were evaluated by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay. The effect of EGCG on CIA in rats was examined clinically and immunohistochemically. Results EGCG inhibited OSM-stimulated CCL2 expression in primary human osteoblasts and MG-63 cells. In MG-63 cells, EGCG alleviated the OSM-induced phosphorylation of Raf-1 at Ser338 but restored the dephosphorylation of Raf-1 at Ser259. EGCG increased the activity of PI 3-kinase, the level of phosphorylated Akt (Ser473), and binding between Raf-1 and active Akt. EMSA and ChIP assay revealed that EGCG attenuated activator protein 1 (AP-1)–CCL2 promoter interaction, possibly by reducing c-Fos synthesis. Codistribution of CD68+ macrophages and CCL2+ osteoblasts in osteolytic areas was obvious in the CIA model. Administration of EGCG markedly diminished the severity of CIA, macrophage infiltration, and the amount of CCL2-synthesizing osteoblasts. Conclusion By stimulating PI 3-kinase activity, EGCG promoted Akt/Raf-1 crosstalk, resulting in decreased AP-1 binding to CCL2 promoter, and finally reduced CCL2 production in osteoblasts. EGCG alleviated the severity of CIA, probably by suppressing CCL2 synthesis in osteoblasts to diminish macrophage infiltration. Our data support the therapeutic potential of EGCG on arthritis.

To compare the results of 3 methods of recognizing internal derangements with a clicking sound on condylar movement: 2 function-based methods (clinical examination and condylar movement recording) and 1 anatomy-based method (magnetic resonance imaging [MRI]).For the recognition of an anterior or posterior disc displacement with reduction and of hypermobility within the temporomandibular joint (TMJ), 42 participants underwent a clinical examination, an opto-electronic movement recording, and an MRI scan. The examinations were executed in a single-blind design, with different experienced examiners for each technique. In addition, for 10 randomly chosen participants, the condylar movement recordings and the MRI scans were carried out twice. Without the examiners' knowledge, these second recordings were added to the other data.Intraobserver reliability for the recognition of internal derangements was excellent for condylar movement recording (kappa = 0.86) and fair to good for MRI (kappa = 0.73). Intermethod agreement was fair to good (kappa = 0.59) between the 2 function-based techniques. However, intermethod agreement between the anatomy-based MRI technique and either of the 2 function-based techniques was poor (for condylar movement recording, kappa = 0.15; and for clinical examination, kappa = 0.12).There is a great discrepancy between the diagnoses for internal derangements based upon anatomical TMJ characteristics and those based on functional TMJ characteristics. For a function-based diagnosis, there is probably no need for the sophisticated technique of condylar movement recording, since that method shows fair to good agreement with a carefully performed clinical examination.

Accurate measurement of the three-dimensional (3D) kinematics of the temporomandibular joint (TMJ) in vivo is essential for relevant clinical applications. Existing measurement methods are either of limited accuracy, difficult to implement, or interfere with TMJ movement. This study develops a marker-cluster registration method (MCRM) for the measurement of the 3D kinematics of the TMJ using low-radiation-dose dental cone-beam computed tomography (CBCT) with fluoroscopy; and to determine experimentally the accuracy and precision using a porcine cadaveric model. The MCRM uses fluoroscopic images and a marker-cluster model (MCM), derived from the CBCT data, to estimate the spatial poses of the maxilla and mandible, and thus the TMJ. The method was found to have measurement errors of 1.00 mm (standard deviation: 0.68 mm) for all translations and 0.15° (standard deviation: 0.11°) for all rotations. For initial bone poses with root-mean-square target registration errors of 0-50 mm for the maxilla and 0-60 mm for the mandible, the successful registration rate was as high as 99%. With high accuracy and registration rate, the proposed method will be useful for the measurements of the 3D kinematics of the TMJ in vivo for scientific and clinical applications.

Accurate measurement of the three-dimensional (3D) motion of the mandible in vivo is essential for relevant clinical applications. Existing techniques are either of limited accuracy or require the use of transoral devices that interfere with jaw movements. This study aimed to develop further an existing method for measuring 3D, in vivo mandibular kinematics using single-plane fluoroscopy; to determine the accuracy of the method; and to demonstrate its clinical applicability via measurements on a healthy subject during opening/closing and chewing movements.The proposed method was based on the registration of single-plane fluoroscopy images and 3D low-radiation cone beam CT data. It was validated using roentgen single-plane photogrammetric analysis at static positions and during opening/closing and chewing movements.The method was found to have measurement errors of 0.1 ± 0.9 mm for all translations and 0.2° ± 0.6° for all rotations in static conditions, and of 1.0 ± 1.4 mm for all translations and 0.2° ± 0.7° for all rotations in dynamic conditions.The proposed method is considered an accurate method for quantifying the 3D mandibular motion in vivo. Without relying on transoral devices, the method has advantages over existing methods, especially in the assessment of patients with missing or unstable teeth, making it useful for the research and clinical assessment of the temporomandibular joint and chewing function.

Background/purpose Nowadays, mini-implant anchorage is incorporated for achieving a variety of orthodontic treatment goals. However, when a miniscrew is located in the interdental area, potential root contact may lead to miniscrew mobility or even failure. Therefore, miniscrew/root contact and possible tissue responses, including root repair, were histologically investigated in the current study. Materials and methods Eight miniscrews were surgically placed in a single dog mandible. Among these, four miniscrews (experimental group) were intentionally placed in contact with a root and then retained for different time durations, three (control group) were also intentionally placed in contact with a root but were immediately removed after insertion, and one was placed without root contact and was retained for 24 weeks. The animal was sacrificed after 24 weeks. Results and conclusions (1) Tissue surrounding roots damaged by a miniscrew showed a significant inflammatory response. (2) Root resorption was occasionally observed after 3 weeks following insertion of a miniscrew even if the miniscrew was not in direct contact with the root. (3) Root repair was noted with a cementoblast lining along the resorption surface at as early as 3 weeks after miniscrew insertion. Alveolar bone filled in the lesion when the root damage was large so that the contour of the alveolar bone followed that of the damaged root, with the width of the periodontal ligament space being maintained. (4) Stable miniscrews were mainly those which did not contact adjacent roots, and for which the surrounding tissue showed only a small inflammatory response with some extent of direct bone contact around the miniscrew. On the contrary, most of the failed miniscrews were those which had direct contact with adjacent roots, and which exhibited severe tissue inflammation and were covered by thick layers of soft tissue. Failure was detected 3 weeks after insertion. Surprisingly, the epithelial lining surrounding the miniscrews might not have spontaneously resolved 6 weeks after screw removal. Persistent infection in the sinus tract was noted, and this would require attention.

Background/purpose To identify how dentoalveolar changes compensate for proper overbite in extreme vertical facial patterns. Materials and methods Lateral cephalometric roentgenograms of preorthodontic adult patients with hyperdivergent ( n = 49; SN-mandibular plane (MP) angle greater than 38 degrees) and hypodivergent ( n = 38; SN-MP angle less than 28 degrees) skeletal patterns were selected. Skeletal-vertical (SV) variables were selected and summarized via stepwise regression methods and principal component analysis (PCA) in these two groups. Multiple regression analyses were performed to determine the relationship between overbite (OB) as the dependent variable and the PCA-derived SV, dental height (DH), and dental inclination (DI) as the independent variables. Results Hyperdivergent patients have the tendency of anterior open bite. The natural dentoalveolar compensatory mechanism is manifested in shorter upper molar height and larger lower incisor height. Hypodivergent patients have no tendency of anterior deep bite. The shorter upper and lower incisor DHs and larger incisal inclination achieved dentoalveolar compensatory mechanism in these patients. Conclusion For orthodontically closing the open bite, intruding upper posteriors and extruding lower anteriors are appropriate ways to simulate the natural occurring compensation. To eliminate deep bite in a low mandibular plane patient, intruding upper and lower anteriors and proclining anteriors will achieve good overbite. Imitating the natural dentoalveolar compensation by using temporary anchorage devices at appropriate sites for intruding teeth helps to resolve orthodontic vertical problems.