Association between sexual maturation and anterior disc displacement of temporomandibular joint in adolescents aged 13-14 years.

OBJECTIVES: To investigate the association between sexual maturation and anterior disc displacement (ADD) of temporomandibular joint (TMJ). MATERIALS AND METHODS: Adolescents aged 13-14 years old, attending the first grade of one private junior school, were recruited. Magnetic resonance imaging (MRI) was used to confirm ADD, in addition, the serum levels of sex hormones were tested. Secondary sex characteristics, psychological evaluations, oral health-related behaviors, and sociodemographic characteristics were also collected. RESULTS: A total of 440 teenagers were included, of which the prevalence of ADD was 17.7%. Subgroup analysis revealed that age at menarche in girls and nocturnal emission, laryngeal prominence, voice change, and facial hair in boys showed significant differences between the ADD group and the normal population (all p < 0.05). The serum levels of prolactin in girls (12.23 and 9.82 ng/ml) and testosterone in boys (3.65 and 2.48 ng/dl) were significantly higher in the ADD group compared to the normal population, respectively (both p < 0.05). CONCLUSIONS: This study suggested that sexual maturation has a significant association with ADD both in boys and girls. The increased serum levels of testosterone in boys and prolactin in girls might contribute to the occurrence of TMJ ADD. CLINICAL RELEVANCE: This study provides key data to support and inform longitudinal studies as well as to explain why ADD prefers in adolescents. Main findings can also be used to prevent the occurrence of ADD and secondary jaw deformities.

Effect of arthroscopic discopexy on condylar growth in adolescents with temporomandibular joint disc displacement without reduction: A retrospective self-controlled case series study.

This study was a retrospective self-controlled study that aimed to evaluate the effect of arthroscopic discopexy on condylar height and mandibular position in adolescents with temporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR). Patients between 10 and 20 years of age and diagnosed with bilateral TMJ ADDwoR by magnetic resonance image (MRI) were included in this study. All patients underwent a period of natural course before arthroscopic surgery and then a follow-up period postoperatively. Changes in condylar height and mandibular position were measured by MRI and X-ray radiographs. Data were analyzed by paired t-test, Pearson correlation analysis, and generalized estimating equations. This study comprised a total of 40 patients with a mean age of 14.80 years. Pearson correlation analysis showed correlations between condylar height and mandibular position changes. The condylar height change during the post-operative period was significantly higher than that during natural course period (3.57 mm, p < 0.001). The changes in mandibular position (including ANB angle, SNB angle, and Pog-Np) were significant different (all p < 0.05) between the two periods. This study found that arthroscopic discopexy can promote condylar growth and correct dentofacial deformity in adolescents with bilateral TMJ ADDwoR.

Association between bilateral condylar resorption and reduced volumes of the craniofacial skeleton and masticatory muscles in adult patients: A retrospective study.

Objectives: This retrospective cohort study aimed to analyze volumes of craniomaxillofacial bone and masticatory muscles of young adults with bilateral idiopathic condylar resorption. Methods: This was a retrospective cohort study of 84 adults with bilateral idiopathic condylar resorption (BCR) and 48 adults with normal temporal-mandibular joint (TMJ) matched for age and sex (mean age, 23.2 ± 3.6 years). The volumes of craniomaxillofacial bone and masticatory muscles, as well as intercondylar angle were measured. Unpaired t-tests and Pearson correlation tests were applied to analyze the data. Multivariable linear regression models were used to estimate the association between bilateral condylar volume and volumes of craniomaxillofacial bone and masticatory muscles adjusted for age, sex, and disc status. Results: Compared to the control group, the BCR group displayed significant decreased volumes of craniomaxillofacial bone (p < 0.001), craniomaxillofacial bone without mandible (p < 0.001), mandible (p < 0.001), mandible without mandibular condylar process (p < 0.001), bilateral masseter muscle (p < 0.001) and bilateral temporalis muscle (p < 0.001), as well as the intercondylar angle (p < 0.001). These variables were significantly correlated to the volume of mandibular condylar process (0.5< r < 0.8; p < 0.001). By linear regression analyses, significant associations were found for the bilateral condylar volume with craniomaxillofacial bone volume and mandible bone volume. Conclusions: Young adults with BCR displayed smaller volumes of craniomaxillofacial skeleton and masticatory muscles, and smaller intercondylar angle than the normal patients. The craniofacial musculoskeletal volume and intercondylar angle are associated with mandibular condylar process volume.

Module-combinatorial design and screening of multifunctional polymers based on polyaspartic acid for DNA delivery.

It is crucial to develop non-viral gene vectors that can efficiently and safely transfect plasmid DNA into cells. Low transfection efficiency and high cytotoxicity of cationic polymers hinder their application as gene carriers. Modification of cationic polymers has emerged as an attractive strategy for efficient and safe nucleic acids delivery. In this study, a simple and rapid method is developed to synthesize a series of multifunctional polymers by utilizing biodegradable polyaspartic acid as the backbone and modifying it with three modules. This one-component polymer possesses capabilities for nucleic acid condensation, cellular uptake, and endosomal escape. Polymers containing imidazole, triazole, or pyridine group exhibited promising transfection activity. Substituted with dodecylamine or 2-hexyldecan-1-amine enhance cellular uptake and subsequent transfection. Furthermore, the influence of ionizable amine side chains on gene delivery is investigated. Two optimal polymers, combined with the avian encephalomyelitis virus (AEV) plasmid vaccine, induced robust specific antibody responses and cellular immune responses in mice and chickens. Through module-combination design and screening of polyaspartamide polymers, this study presents a paradigm for the development of gene delivery vectors.

N-MID, P1NP, ß-CTX, and phosphorus in adolescents with condylar resorption.

OBJECTIVE: Condylar resorption (CR) is a temporomandibular joint disease that causes various physical or functional defects. We aimed to find the association between CR and bone metabolism levels. STUDY DESIGN: In this study, we recruited patients visiting the Orthodontic Clinic at Shanghai Ninth People's Hospital from January 2020 to September 2021. Patient characteristics, magnetic resonance imaging examination results, bone mineral density (BMD), Z-score, bone turnover markers, minerals, and hormones were collected and analyzed. RESULTS: The 89 participants were divided into CR (n = 46) and normal (n = 43) groups. Univariate logistic regression showed that N-terminal mid-fragment of osteocalcin (N-MID), procollagen type 1 N-terminal propeptide (P1NP), ß-C-terminal telopeptide of type 1 collagen (ß-CTX), and phosphorus (P < .001 for all) were protective factors, and BMD (P = .047) was a risk factor for CR. Multivariable logistic regression showed that N-MID, P1NP, ß-CTX, and phosphorus (odds ratio <1, P < .05 for all) were protective factors for CR. Receiver operating characteristic curves showed these indicators to effectively predict CR occurrence (area under the curve >0.7; P < .001). CONCLUSION: Adolescents with low serum N-MID, P1NP, ß-CTX, and phosphorus levels were associated with a higher risk of CR. We suggest that these indicators can guide clinicians in the early detection and prevention of CR in adolescents.

Characteristics of patients with temporomandibular joint idiopathic condylar resorption.

OBJECTIVE: To investigate characteristics of temporomandibular joint (TMJ) idiopathic condylar resorption (ICR) and analyze the related factors. METHODS: A total of 755 consecutive patients (150 with ICR and 605 with anterior disc displacement [ADD]) from July 2015 to December 2018 were recruited. A comprehensive questionnaire characterizing the multidimensional impact of the TMJ was designed. Clinical examination and radiological evaluation were also performed. The odds ratio for each variable in the ICR group versus the ADD group was computed using logistic regression analysis. RESULTS: Multivariate logistic regression analysis showed significant correlations between mouth opening restriction, disease course, mandibular retrusion, mandibular retrusion progression, skeletal Class II profile, and overjet in ICR patients. CONCLUSION: These results suggest that a longer ADD disease course might have a strong relationship with ICR.

Rapid induction and long-term self-renewal of neural crest-derived ectodermal chondrogenic cells from hPSCs.

Articular cartilage is highly specific and has limited capacity for regeneration if damaged. Human pluripotent stem cells (hPSCs) have the potential to generate any cell type in the body. Here, we report the dual-phase induction of ectodermal chondrogenic cells (ECCs) from hPSCs through the neural crest (NC). ECCs were able to self-renew long-term (over numerous passages) in a cocktail of growth factors and small molecules. The cells stably expressed cranial neural crest-derived mandibular condylar cartilage markers, such as MSX1, FOXC1 and FOXC2. Compared with chondroprogenitors from iPSCs via the paraxial mesoderm, ECCs had single-cell transcriptome profiles similar to condylar chondrocytes. After the removal of the cocktail sustaining self-renewal, the cells stopped proliferating and differentiated into a homogenous chondrocyte population. Remarkably, after transplantation, this cell lineage was able to form cartilage-like structures resembling mandibular condylar cartilage in vivo. This finding provides a framework to generate self-renewing cranial chondrogenic progenitors, which could be useful for developing cell-based therapy for cranial cartilage injury.