Application of temporomandibular joint prosthesis in oral and maxillofacial surgery: strategic thinking and prospects.

The temporomandibular joint (TMJ) is the critical functional unit in the human stomatognathic system. Damage of the TMJ causes orofacial dysfunction and secondary jaw deformities, leading to seriously decreased quality of life in patients. The TMJ prosthetic replacement is an important treatment method for severe joint destruction because of its remarkable advantages compared with other methods. In recent years, this technique has gradually attracted wide attention in China, but it has not been popularized on a large scale in our country because of several limitations. Thus, in this study, the clinical experience of patients with TMJ prosthetic replacement in clinical units was summarized, and the treatment principles, treatment processes, and technical advantages were systematically discussed, aiming to promote the popularization and application of TMJ prosthetic replacement in China.

Comparing microstructural and micromechanical deformation of the TMJ disc in two anterior disc displacement models.

OBJECTIVE: Anterior disc displacement (ADD) has been used to establish temporomandibular joint disorder (TMD) models. Based on whether preserve of the retrodiscal attachment, the modelling methodologies include ADD with dissecting the retrodiscal attachment (ADDwd) and ADD without dissecting the retrodiscal attachment (ADDwod). This article aims to determine which model better matches the micromechanical and microstructural progression of TMD. METHODS: Through meticulous microscopic observations, the microstructure and micromechanical deformation of the TMJ discs in ADDwd and ADDwod rabbit models were compared at 2 and 20 weeks. RESULT: Scanning electron microscopy and transmission electron microscopy showed that collagen fibres became slenderized and straightened, collagen fibrils lost diameter and arrangement in the ADDwd group at 2 weeks. Meanwhile, nanoindentation and atomic electron microscopy showed that the micro- and nano- mechanical properties decreased dramatically. However, the ADDwod group exhibited no significant microstructure and micromechanical deformations at 2 weeks. Dissection of the retrodiscal attachment contribute in the acceleration of disease progression at the early stage, the devastating discal phenotype remained fundamentally the same within the two models at 20 weeks. CONCLUSION: ADDwod models, induced stable and persistent disc deformation, therefore, can better match the progression of TMD. While ADDwd models can be considered for experiments which aim to obtain advanced phenotype in a short time.

Accessing Furan-Linked Methylene Oxindoles/Benzofurans via Stereoselective Palladium-Catalyzed Domino Cyclization/Cycloisomerization.

A palladium-catalyzed domino cyclization/cycloisomerization reaction of alkyne-tethered carbamoyl chlorides with (E)-ß-chloroenones is reported. This reaction proceeds via a syn-carbopalladation of the alkyne, followed by a vinyl-PdII-catalyzed cycloisomerization of the (E)-ß-chloroenone cascade, which provides an efficient method to synthesize furan-linked methylene oxindoles. The reaction features stereodefined vinyl-PdII species, high to excellent 5-exo/6-endo selectivity, excellent Z/E selectivity, and the sequential formation of three bonds and bis-heterocycles. The strategy for the synthesis of furan-containing benzofurans has also been demonstrated.

Comparison of the biomechanical behavior between commercial and 3D-printed patient-specific Ti6Al4V L-Shaped titanium plates following le fort i osteotomy using finite element analysis: A technical Note.

OBJECTIVE: To evaluate and compare the biomechanical behavior of three-dimensionally (3D) printed patient-specific Ti6Al4V with commercially made titanium mini plates following Lefort-I osteotomy using finite element analysis. METHODS: Le Fort I osteotomy was virtually simulated with a 5 mm maxillary advancement and mediolateral rotation in the coronal plane, resulting in a 3 mm gap on the left side's posterior. Two fixation methods were modeled using software to compare 3D-printed Ti6Al4V and commercial titanium mini plates, both featuring a 4-hole l-shape with thicknesses of 0.5 mm and 0.7 mm at the strategic piriform rim and zygomaticomaxillary buttress locations. Using ANSYS R19.2, finite element models were developed to assess the fixation plates and maxilla's stress, strain, and displacement responses under occlusal forces of 125, 250, and 500 N/mm². RESULTS: This comparative analysis revealed slight variation in stress, strain, and displacement between the two models under varying loading conditions. Stress analysis indicated maximum stress concentrations at the vertical change in the left posterior area between maxillary segments, with the Ti6Al4V model exhibiting slightly higher stress values (187 MPa, 375 MPa, and 750 MPa) compared to the commercial titanium model (175 MPa, 351 MPa, and 702 MPa). Strain analysis showed that the commercial titanium model recorded higher strain values at the bending area of the l-shaped miniplate. Moreover, displacement analysis revealed a maximum of 3 mm in the left posterior maxilla, with the Ti6Al4V model demonstrating slightly lower displacement values under equivalent forces. CONCLUSION: The maximum stress, strain, and segment displacement of both fixation models were predominantly concentrated in the area of the gap between the maxillary segments. Notably, both fixation models exhibited remarkably close values, which can be attributed to the similar design of the fixation plates.

The effect of different hybrid rigid internal fixation techniques on the postoperative stability following a mandibular advancement using a bilateral sagittal split ramus osteotomy: A retrospective three-dimensional comparative study.

OBJECTIVE: To three-dimensionally evaluate post-operative mandibular stability following bilateral sagittal split ramus osteotomies between hybrid and non-hybrid rigid internal fixation techniques. MATERIALS AND METHOD: Seventy adults with skeletal class II deformity who underwent bilateral split sagittal osteotomy with mandibular advancement were included. Patients were divided into four groups based on their fixation techniques: hybrid technique (HT) groups I, II, and IV received a 4-hole 2 mm miniplate with either a bicortical screw (BS), additional 2 mm 4-hole miniplate, or two-hole miniplate, while non-HT group III received a 4-hole 2 mm miniplate with four mini-screws (MS). Measurements were taken pre-operatively (T0), immediately postoperatively (T1), and ≥1 year after surgery (T2) using 3D Slicer software. RESULTS: Age, sex, and follow-up period did not correlate significantly with postoperative relapse or stability. Significant differences were observed in the advancement on the right side between groups II, III, and IV and on the left side between groups I, III, and IV. However, the type of surgical intervention showed no significant effect on postoperative relapse and stability. All groups of fixations showed satisfactory stability with irrelevant relapse (< 2 mm or 2°). CONCLUSION: The study demonstrated satisfactory and comparable stability among different fixation groups on patients undergoing mandibular advancement following bilateral split sagittal osteotomy. The results highlighted the importance of considering the degree of advancement when planning orthognathic surgery and managing postoperative outcomes.

Isolation, characterization, identification and quantification of 6-F oxyphenisatin dipropionate, a novel illegal additive, from a fruit-flavored jelly.

Objective: This study is aimed to screen, identify and detect illegal additives from healthcare products which claim or imply to have weight-loss effects. Method: Ultra-high performance liquid chromatography-quadruple-time-of-flight mass spectroscopy (UPLC-Q-TOF/MS) was employed to perform non-targeted screening of illegal additives from a total of 26 batches of healthcare products with weight-loss effects. A novel oxyphenisatin dipropionate analog was discovered in a fruit-flavored jelly that was not clearly labeled as containing added drugs. After being separated and purified by silica gel column chromatography, the analog was unambiguously characterized by one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopies. The molecular structure of the analog was finally identified by comparing the spectra of the analog with those of suspected candidates prepared by de novo synthesis strategy. Thereafter, a sensitive and precise reversed phase ultra performance liquid chromatography coupled with photodiode array (UPLC-PDA) detection method was developed and verified for the determination of the analog in 15 batches of real samples. Results: In the MS/MS spectra, the signal intensity of mass/charge ratios (m/z, 242 and 214) of the novel analog fragments was highly similar to that of mass/charge ratios (m/z, 224 and 196) of oxyphenisatin dipropionate fragments. Additionally, the 1D NMR spectrum of the analog was completely consistent with that of one of the suspected candidates prepared by the de novo synthesis strategy. Based on the above analysis, the structure of the analog was determined as 3,3-bis[4'-(propionyloxy)phenyl]-6-fluoro-2-oxoindoline, which was briefly named 6-F oxyphenisatin dipropionate. A developed quantitative method showed good linearity (R2 > 0.999) in a concentration range of 1.0-100 µg/mL. The limits of detection (LOD) and quantification (LOQ) for the analog was 3 mg/kg and 10 mg/kg, respectively. The average recoveries of the analog from spiked three different matrix samples in low (1 time of LOQ), medium (2 times of LOQ), and high (10 times of LOQ) concentrations were varied from 93.9 % to 107.8 % with a precision of 0.03-1.56 %. Results of quantitative analysis in 15 batches of healthcare products revealed that the content of 6-F oxyphenisatin dipropionate in a fruit-flavored jelly and a solid beverage was 118 mg/kg and 330 mg/kg, respectively. Conclusion: In terms of its structure, 6-F oxyphenisatin dipropionate replaces hydrogen atom by the fluorine atom at position 6 on the indolinone fragment in oxyphenisatin dipropionate. To our best knowledge, 6-F oxyphenisatin dipropionate has never been detected as an illegal additive in foods. Such illegal addition of the analog to foods is more concealing, thus the supervision and testing departments should attach great importance to its application in food markets.

Bone Volume Analysis and Associated Influencing Factors in Mandibular Distraction Osteogenesis: A Retrospective Analysis.

BACKGROUND: Distraction osteogenesis is a progressively popular technique for maxillofacial bone reconstruction, but there is a notable gap in the analysis of bone volume within the distraction segment and the exploration of associated influencing factors. PURPOSE: The purpose of this study was to quantitatively analyze the new bone volume and the distraction gap volume in the three-dimensional (3D) model and explore the influencing factors associated with the percentage of the new bone volume to the distraction gap volume. STUDY DESIGN, SETTING, SAMPLE: This retrospective study included patients who underwent maxillofacial distraction osteogenesis treatment at the West China Hospital of Stomatology between 2014 and 2022, utilizing the mandibular distractor (Cebei, Ningbo, China). Exclusion criteria encompassed individuals with incomplete clinical or radiographical records as well as those who loss to follow-up. PREDICTOR VARIABLE: The predictor variables were age, sex, diagnosis, consolidation period duration, distraction modality, osteotomy area, distraction gap volume, and proximal bone segment volume. MAIN OUTCOME VARIABLE(S): The outcome variable was osteogenic effect which defined as the percentage of the new bone volume to the distraction gap volume in the 3D model. COVARIATES: Not applicable. ANALYSES: T-tests were used to describe categorical variables, and Pearson correlation analysis was used to describe continuous variables. Linear regression was employed to assess the predictiveness of variables for osteogenic effect. Data are described as mean ± standard deviation; statistical significance was established at a P value < .05. RESULTS: The study sample contained 35 patients(11 males and 24 females) with a mean age of 21.17 ± 11.82 years (range: 5 to 47 years) were included. The mean osteogenic effect of all samples was 78.89 ± 24.70%. Multiple linear regression models confirmed that the osteogenic effect was significantly influenced by the distraction gap volume (P = .003), proximal bone segment volume (P = .009), osteotomy area (P = .034), diagnosis (P = .004), and distraction modality (P = .021). CONCLUSION AND RELEVANCE: The percentage of new bone mass to simulated volume based on 3D model measurement can serve as an effective quantitative indicator for evaluating the osteogenic effect; our study demonstrates that distraction gap volume, proximal bone segment volume, osteotomy area, diagnosis, and distraction modality can statistically significantly influence the osteogenic effect.

Arthroscopic reduction and rigid fixation of the anteriorly displaced temporomandibular joint disc without reduction using titanium screw: a case series.

OBJECTIVES: To evaluate the effectiveness of arthroscopic reduction and rigid fixation (ARRF) using a suture-free titanium screw as a treatment approach to temporomandibular joint's (TMJ) anterior disc displacement without reduction (ADDwoR) and assess its impact on clinical outcomes, including improvements in symptoms related to TMJ disorders. MATERIALS AND METHODS: A series of twenty patients presented to the Department of Orthognathic and Temporomandibular Surgery at West China Hospital of Stomatology between September 2022 and January 2023, complaining of symptoms such as pain, clicking, and limited mouth opening. Standard magnetic resonance image (MRI) imaging T1 and T2 sequences in both sagittal and coronal views study with closed and maximal open mouth positions were taken preoperatively to assess the disc's position, integrity, and shape. Also, cone-beam computed tomography (CBCT) scans images to find any degenerative changes and evaluate the condylar bone's features and volume. Additionally, the clinical examination assesses limited oral opening, mechanical pain, and the presence of any noises such as clicking and crepitus. All cases were treated under general anesthesia using the arthroscopic release, reduction, and rigid fixation of the TMJ's ADDwoR to establish a normal disc-condyle relationship and to restore the functional position. RESULTS: Patients' symptoms, such as pain and mouth opening, improved significantly following the arthroscopic treatment. Postoperative MRI and CBCT imaging follow-up conducted at 6 months demonstrated the stable position of the reduced TMJ disc and the fixation screw. Notably, none of the patients exhibited signs of relapse during this follow-up period. CONCLUSION: Overall, the ARRF of TMJ's ADDwoR using a suture-free titanium screw proved to be safe and provides satisfactory results, in addition to the several advantages of using suture-free titanium screws, such as biocompatibility, strong fixation, and durability. However, it is a technically demanding procedure requiring extensive, long-term training. CLINICAL RELEVANCE: ARRF using a cost-effective fixation titanium screw to treat ADDwoR emerges as a clinically effective minimally invasive approach.

Comparison of Class II open bite correction by temporomandibular joint prostheses or bimaxillary orthognathic surgery.

INTRODUCTION: The aim of this study was to evaluate the outcome of skeletal Class II and anterior open bite patients who received simultaneous Le fort I osteotomies with temporomandibular joint (TMJ) prostheses or bimaxillary orthognathic surgery. MATERIALS AND METHODS: Patients with condylar resorption (CR) were treated by TMJ prostheses and orthognathic surgery and divided into two groups. Cephalometric radiographs were obtained before and after operation to find out the surgical alteration by comparing measures at different time points. RESULTS: 23 patients were included. Mean overbite of the patients was increased by 3.39 mm in TMJ prostheses group and 3.24 mm in orthognathic group. Occlusal plane angle was averagely rotated -6.06° and 1.31°; mandibular plane counterclockwise rotated 12.23° and 5.81°, respectively. The increase of ramus height in TMJ prostheses group were significantly greater than orthognathic surgery group (8.02 ± 1.96 mm vs. -0.09 ± 1.29 mm). The overall treatment effect was stable in both groups during the 1-year follow up. DISCUSSION: Two surgical plans seem to be reliable treatments of anterior open bite and mandibular retrognathism caused by temporomandibular disease. TMJ prostheses with simultaneous Le fort I osteotomies close open bite by lengthening the height of ramus and rotating maxillo-mandibular complex counterclockwise, while bimaxillary orthognathic surgery by rotating maxilla clockwise and mandible counterclockwise without rebuilding ramus.

Understanding the Mechanics of the Temporomandibular Joint Osteochondral Interface from Micro- and Nanoscopic Perspectives.

The condylar cartilage of the temporomandibular joint (TMJ) is connected to the subchondral bone by an osteochondral interface that transmits loads without causing fatigue damage. However, the microstructure, composition, and mechanical properties of this interface remain elusive. In this study, we found that structurally, a spatial gradient assembly of hydroxyapatite (HAP) particles exists in the osteochondral interface, with increasing volume of apatite crystals with depth and a tendency to form denser and stacked structures. Combined with nanoindentation, this complex assembly of nanoscale structures and components enhanced energy dissipation at the osteochondral interface, achieving a smooth stress transition between soft and hard tissues. This study comprehensively demonstrates the elemental composition and complex nanogradient spatial assembly of the osteochondral interface at the ultramicroscopic scale, providing a basis for exploring the construction of complex mechanical models of the interfacial region.

Studying positional changes of the disc-condyle-fossa complex in ADDWoR patients after TMJ disc repositioning surgery.

OBJETIVES: To investigate the positional changes in the temporomandibular joint (TMJ) disc-condyle-fossa complex of patients with anterior disc displacement without reduction (ADDWoR) and to evaluate the effect of disc repositioning (DR) surgery. MATERIAL AND METHODS: Fifteen patients with unilateral ADDWoR (30 joints) were included. MRI of the TMJ was performed at T0 (1 week before surgery), T1 (1 month after surgery), and T2 (9-12 months after surgery). The glenoid fossa, disc, and condyle were reconstructed and analyzed using Mimics software. RESULTS: In the patients with unilateral ADDWoR, the disc on the ADD side showed a tendency to downward shift in the coronal direction and forward shift in the sagittal direction; the condyle of ADD side showed a tendency to backward shift in the sagittal direction and upward shift in the coronal direction. When comparing the same ADDwoR TMJ at T0, T1, and T2, the disc was found to move upward and backward after DR surgery at T1 and T2, and the condyle was found to move upward and backward after DR surgery at T1 but returned to the original position at T2. CONCLUSIONS: ADDWoR leads to forward and downward displacement of the disc relative to the condyle and upward displacement of the condyle relative to the tuberosity. DR surgery improved upon the structural abnormalities of the TMJ complex, for which stability was maintained as determined in the 9 to 12 month postoperative follow-up. CLINIC RELEVANCE: DR surgery effectively and constantly improves the positional abnormalities of the TMJ complex.

The Dual Role of Small Extracellular Vesicles in Joint Osteoarthritis: Their Global and Non-Coding Regulatory RNA Molecule-Based Pathogenic and Therapeutic Effects.

OA is the most common joint disease that affects approximately 7% of the global population. Current treatment methods mainly relieve its symptoms with limited repairing effect on joint destructions, which ultimately contributes to the high morbidity rate of OA. Stem cell treatment is a potential regenerative medical therapy for joint repair in OA, but the uncertainty in differentiation direction and immunogenicity limits its clinical usage. Small extracellular vesicles (sEVs), the by-products secreted by stem cells, show similar efficacy levels but have safer regenerative repair effect without potential adverse outcomes, and have recently drawn attention from the broader research community. A series of research works and reviews have been performed in the last decade, providing references for the application of various exogenous therapeutic sEVs for treating OA. However, the clinical potential of target intervention involving endogenous pathogenic sEVs in the treatment of OA is still under-explored and under-discussed. In this review, and for the first time, we emphasize the dual role of sEVs in OA and explain the effects of sEVs on various joint tissues from both the pathogenic and therapeutic aspects. Our aim is to provide a reference for future research in the field.

A novel vardenafil analog in a healthcare product: Preparation, characterization, and quantification.

OBJECTIVE: This study is aimed to develop a qualitative and quantitative method to detect a novel vardenafil analogue from a healthcare product, which is claimed to enhance sexual function. Method: The unknown compound was detected by non-targeted screening using ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS). MS2 spectra showed that the characteristic fragment ions of this unknown compound were highly similar to those of vardenafil. This compound was subsequently isolated by silica gel column chromatography and characterized by 1D (dimension) and 2D nuclear magnet resonance (NMR) specta, ultra-violet (UV) spectra, and fourier transform infrared (IR) spectra. A quantitative method for analyzing this identified compound in various healthcare product was developed based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). RESULTS: The unknown compound was identified as 2-(5-((4-ethylpiperazin-1-yl)sulfonyl)-2-propoxyphenyl)-5-methyl-7-propylimidazo.[5,1-f] [1,2,4]triazin-4(3H)-one based on the spectroscopic data. Quantitative results revealed that the matrix calibration curves of this compound had a good linear ranges of 2～50 ng/mL in pressed candy (R2 = 0.998), energy coffee (R2 = 0.999), and health wine (R2 = 0.997), respectively. The matrix effects, recoveries, and limit of quantitation (LOQ) of this compound all met the requirements of quantitative validation. Finally, the content of this compound in 5 batches of positive samples ranged from 1.24 to 7.20 g/kg. Conclusion: This study identified a novel vardenafil analog from a healthcare product and named it O-propyl vardenafil, and this compound was distinguished from vardenafil by the replacement of the ethyl group with a propyl group at the aryl alkyl ether moiety. Our developed quantitative method could meet practical needs. The high positive rate (16.67%) in 30 samples suggested that the related regulators should be alert to O-propyl vardenafil in routine test since it has not been detected ever before.

Heterogeneous Characteristics of the CD90+ Progenitors in the Fibrocartilage of Different Joints.

OBJECTIVE: This study aimed to isolate and compare the mesenchymal stem cell characteristics of CD90+ cells from different fibrocartilage tissues in the temporomandibular joint (TMJ), the knee joint, and the intervertebral joint to further understand the similarities and differences of these 4 fibrocartilage tissues. METHODS: CD90+ cells were isolated from TMJ disc, condylar cartilage, meniscus, and intervertebral disc by using magnetic-activated cell sorting. Cellular assays including 4.5-ethynyl-2'-deoxyuridine labeling, multilineage differentiation, colony formation, and cell migration were conducted to compare their mesenchymal stem cell characteristics. Immunofluorescent staining was performed for observing the expression of actively proliferating CD90+ cells within the tissues. H&E staining and Safranine O staining were used to compare the histological features. RESULTS: The CD90+ cells derived from these 4 fibrocartilage tissues exhibited comparable cell proliferation abilities. However, the cells from the TMJ disc displayed limited multilineage differentiation potential, colony formation, and cell migration abilities in comparison with the cells from the other fibrocartilage tissues. In vivo, there was relatively more abundant expression of CD90+ cells in the TMJ disc during the early postnatal stage. The limited EDU+ cell numbers signified a low proliferation capacity of CD90+ cells in the TMJ disc. In addition, we observed a significant decrease in cell density and a restriction in the synthesis of extracellular proteoglycans in the TMJ disc. CONCLUSION: Our study highlights the spatial heterogeneity of CD90+ cells in the fibrocartilages of different joint tissues, which may contribute to the limited cartilage repair capacity in the TMJ disc.

Divergent chondro/osteogenic transduction laws of fibrocartilage stem cell drive temporomandibular joint osteoarthritis in growing mice.

The anterior disc displacement (ADD) leads to temporomandibular joint osteoarthritis (TMJOA) and mandibular growth retardation in adolescents. To investigate the potential functional role of fibrocartilage stem cells (FCSCs) during the process, a surgical ADD-TMJOA mouse model was established. From 1 week after model generation, ADD mice exhibited aggravated mandibular growth retardation with osteoarthritis (OA)-like joint cartilage degeneration, manifesting with impaired chondrogenic differentiation and loss of subchondral bone homeostasis. Lineage tracing using Gli1-CreER+; Tmfl/-mice and Sox9-CreER+;Tmfl/-mice showed that ADD interfered with the chondrogenic capacity of Gli1+ FCSCs as well as osteogenic differentiation of Sox9+ lineage, mainly in the middle zone of TMJ cartilage. Then, a surgically induced disc reposition (DR) mouse model was generated. The inhibited FCSCs capacity was significantly alleviated by DR treatment in ADD mice. And both the ADD mice and adolescent ADD patients had significantly relieved OA phenotype and improved condylar growth after DR treatment. In conclusion, ADD-TMJOA leads to impaired chondrogenic progenitor capacity and osteogenesis differentiation of FCSCs lineage, resulting in cartilage degeneration and loss of subchondral bone homeostasis, finally causing TMJ growth retardation. DR at an early stage could significantly alleviate cartilage degeneration and restore TMJ cartilage growth potential.

Condylar positional changes and remodeling following bimaxillary anterior segment osteotomy with and without Le Fort I osteotomy: a three-dimensional comparative analysis.

OBJECTIVE: To evaluate 3D condylar displacement and long-term remodeling following the correction of bimaxillary protrusion by anterior segment osteotomy (ASO) with and without Le Fort I surgery. MATERIALS AND METHOD: This retrospective study included 32 adults with bimaxillary protrusion who underwent ASO alone (group 1) or with concomitant Le Fort I osteotomy (group 2). Subject's computed tomography scans at basic (T0), immediate postoperatively (T1), and at 1 year or more follow-up (T2) were collected. The condyle displacement was measured at superior-inferior, lateromedially, and anteroposterior surfaces, while condyle remodeling was measured at the superior, lateral, anterior, medial, and posterior surfaces. All 3D analyses were performed using 3D Slicer software (4.11.2). RESULTS: At T1, 52.7%, 86.7%, and 94.4% of condyles in group 1 were displaced inferiorly, laterally, and posteriorly, respectively, as well as 75%, 89.2%, and 53.5% of condyles in group 2, which had not fully returned to the original preoperative positions at T2. Condylar remodeling was observed in both groups at T2, and no significant difference was found in the overall condylar volume between T1 and T2 in both groups. Patients in group 2 exhibited significant bone resorption at both lateral and anterior surfaces compared to group 1 (P = 0.000 and 0.01, respectively). CONCLUSION: This study's results demonstrated that ASO is associated with a degree of condylar changes even if the posterior mandible is not osteomized. The positional changes vary between bimaxillary ASO alone and those with simultaneous Le Fort I osteotomy. However, both groups' condyle volume remained stable at the long-term follow-up.

Interspecies comparison of temporomandibular joint condylar cartilage extracellular matrix from macro to microscopy.

Interspecies comparisons of the extracellular matrix of temporomandibular joint (TMJ) condylar cartilage are necessary to elucidate the mechanisms underlying its superior mechanical properties, to guide the construction of animal models of TMJ-related diseases, and to establish standards for the engineering of TMJ condylar cartilage. Here we characterize and compare TMJ condylar cartilage from six different species from a materials science perspective, including structure, composition and mechanical properties from the macroscopic to the microscopic level. The gross morphology showed obvious interspecies differences in size and shape, which may be related to the different joint motion patterns. Although the condylar cartilage of all species can be divided histologically into a superficial fibrous layer and a deep hyaline layer, there are significant interspecies differences in the microstructure of the fibrils in the two layers, mainly in the diameter of the fibrils. Compositionally, there were no significant differences in collagen composition between species, but the content of glycosaminoglycans (GAGs) decreased progressively with increasing body size, with the same results obtained by Safranin O staining and biochemical analysis. Mechanically, the elastic modulus of mouse condylar cartilage was significantly higher than that of the other species and tended to decrease with increasing body size. This study shows that the TMJ condylar cartilage of different species has its own specific structure-composition-mechanics matching characteristics for their unique masticatory stress dissipation, and differences in fibril diameter and GAGs content may be the two ultimate factors influencing the differences in cartilage mechanical properties between species, while the condylar cartilage of pigs is most similar to that of humans, suggesting that pigs may be a suitable animal model for TMJ studies.

TMJ anterior disc displacement anchorage surgery: a retrospective study based on a suture-free titanium screw strategy.

OBJECTIVE: To evaluate the feasibility and effectiveness of using a suture-free titanium screw in repositioning anterior disc displacement without reduction (ADDwoR) of the temporomandibular joint (TMJ). METHODS: A consecutive sample of twelve patients (fifteen joints) was included in this study. All patients were diagnosed with ADDwoR and showed limited mouth opening or temporomandibular joint pain symptoms. Suture-free titanium screw was placed in the condyle directly following the disc repositioning. Pre- and postoperative evaluation parameters include operation time, the visual analogue scale for pain (VAS), lateral excursion movements (LEM), maximum interincisal opening (MIO), and disc length and position on MRI. In addition, the mandibular condyle height was also measured. Statistical significance was considered when p < 0.05. RESULTS: The unilateral operation time was 58.54 ± 5.43 min; during the 6-month period after the operation, the VAS values decreased from 87 ± 6.34 to 14.08 ± 6.65. The MIO increased from 30.07 ± 4.73 to 39.89 ± 1.69 mm (p = 0.01). The TMJ disc length was prolonged from 8.23 ± 1.12 to 11.51 ± 1.29 mm. The condyles showed significant remodeling, and the height of the condyle increased from 18.24 ± 4.12 increase to 19.6 ± 4.31 mm. The LEM was increased from 5.27 ± 0.51 to 6.36 ± 0.62 mm. The MRI images showed the stability of the disc in position during the opening and closing of the mouth. The TMJ disc position was stable during the follow-up period. CONCLUSION: Anteriorly displaced articular disc can be repositioned by a suture-free titanium screw strategy. This technique is an alternative method to address ADDwoR.

Effect of the magnitude of condylar head displacement on the TMJ function in skeletal class II patients undergoing different degrees of mandibular advancement: A retrospective comparative study.

PURPOSE: This study aimed to compare the condylar head displacement (CHD) after bilateral sagittal split ramus osteotomy (BSSO) between different degrees of mandibular advancement in skeletal class II patients and to evaluate whether the temporomandibular joint (TMJ) function would be affected. PATIENTS AND METHODS: Fifty-nine patients (118 condyles) were included in this retrospective study and were divided into three groups based on the distance of mandibular advancement. The CHD in three directions, x (sagittal direction), y (coronal direction), and z (axial direction), was measured before operation (T0), immediately after operation (T1), and at least 6 months after operation (T2), and the TMJ function of patients was followed up and scored using the Helkimo index system. All the abovementioned data were statistically analyzed, and p < 0.05 was considered the statistical difference standard. RESULT: During the BSSO surgery, the condyle was predominantly displaced in a lateral, posterior, and superior direction whenever in T1 and T2, even though the degree of CHD was different. Regarding the amount of CHD, the large advancement group was higher than the other two groups in T1 and T2 (p＜0.01). The Helkimo index scores of the three groups were evaluated, and there was no significant statistical difference between the Ai and Di index of the three groups. CONCLUSION: In our center, CHD occurred in lateral, posterior, and superior directions following mandibular advancement in skeletal class II patients, with a positive correlation between the CHD and the mandibular advancement; however, the TMJ function of the three groups did not show significant differences.

Near-Infrared Light-Activated Mesoporous Polydopamine for Temporomandibular Joint Osteoarthritis Combined Photothermal-Chemo Therapy.

The treatments generally employed for temporomandibular joint osteoarthritis (TMJOA) involve physical therapy and chemotherapy, etc., whose therapeutic efficacies are impaired by the side effects and suboptimal stimulus responsiveness. Although the intra-articular drug delivery system (DDS) has shown effectiveness in addressing osteoarthritis, there is currently little reported research regarding the use of stimuli-responsive DDS in managing TMJOA. Herein, we prepared a novel near-infrared (NIR) light-sensitive DDS (DS-TD/MPDA) by using mesoporous polydopamine nanospheres (MPDA) as NIR responders and drug carriers; diclofenac sodium (DS) as the anti-inflammatory medication; and 1-tetradecanol (TD) with a phase-inversion temperature of 39 °C as the drug administrator. Upon exposure to 808 nm NIR laser, DS-TD/MPDA could raise the temperature up to the melting point of TD through photothermal conversion, and intelligently trigger DS release. The resultant nanospheres exhibited an excellent photothermal effect and effectively controlled the release of DS through laser irradiation to accommodate the multifunctional therapeutic effect. More importantly, the biological evaluation of DS-TD/MPDA for TMJOA treatment was also performed for the first time. The experiments' results demonstrated that DS-TD/MPDA displayed a good biocompatibility in vitro and in vivo during metabolism. After injection into the TMJ of rats afflicted with TMJOA induced by unilateral anterior crossbite for 14 days, DS-TD/MPDA could alleviate the deterioration of TMJ cartilage, thus ameliorating osteoarthritis. Therefore, DS-TD/MPDA could be a promising candidate for photothermal-chemotherapy for TMJOA.