Spheroid Culture System, a Promising Method for Chondrogenic Differentiation of Dental Mesenchymal Stem Cells.

The objective of the present work was to develop a three-dimensional culture model to evaluate, in a short period of time, cartilage tissue engineering protocols. The spheroids were compared with the gold standard pellet culture. The dental mesenchymal stem cell lines were from pulp and periodontal ligament. The evaluation used RT-qPCR and Alcian Blue staining of the cartilage matrix. This study showed that the spheroid model allowed for obtaining greater fluctuations of the chondrogenesis markers than for the pellet one. The two cell lines, although originating from the same organ, led to different biological responses. Finally, biological changes were detectable for short periods of time. In summary, this work demonstrated that the spheroid model is a valuable tool for studying chondrogenesis and the mechanisms of osteoarthritis, and evaluating cartilage tissue engineering protocols.

Osteoarthritis of the Temporomandibular Joint: A Narrative Overview.

Background and Objectives: This study reviewed the literature to summarize the current and recent knowledge of temporomandibular joint osteoarthritis (TMJOA). Methods: Through a literature review, this work summarizes many concepts related to TMJOA. Results: Although many signaling pathways have been investigated, the etiopathogenesis of TMJOA remains unclear. Some clinical signs are suggestive of TMJOA; however, diagnosis is mainly based on radiological findings. Treatment options include noninvasive, minimally invasive, and surgical techniques. Several study models have been used in TMJOA studies because there is no gold standard model. Conclusion: More research is needed to develop curative treatments for TMJOA, which could be tested with reliable in vitro models, and to explore tissue engineering to regenerate damaged temporomandibular joints.

[Ehlers-Danlos syndrome: Role of the dentist]. / Le syndrome d'Ehlers-Danlos : rôle du chirurgien-dentiste.

The Ehlers-Danlos syndrome (EDS) is a group of genetic connective tissue disorder due to abnormal collagen synthesis. EDS is characterized by the triad: joint hypermobility - skin hyperextensibility - connective tissue friability leading to vascular and skin fragility. Thirteen forms exist including three main ones: the hypermobile, classical and vascular forms. Given the diversity of clinical manifestations, the diagnosis of EDS is difficult. The management of this syndrome is multidisciplinary and includes the dental surgeon, because EDS can have many oral and dental manifestations. This syndrome can lead to dental, periodontal, mucosal damage and also to joint damage to the manducatory apparatus. The authors, after describing the symptoms of EDS, their manifestations and their detection, will explain the implications in odontostomatology. EDS must be known to the dentist because it can lead to precautions during dental care, and because patients with EDS are more prone to temporomandibular disorders. At the last, the many oral and dental manifestations of EDS give the dentist an important role in screening for this syndrome.

Relationship between natural or iatrogenic malocclusions and temporomandibular disorders: A case control study.

OBJECTIVE: To investigate the link between malocclusions and temporomandibular disorders (TMD) with a focus on iatrogenic malocclusion. Other etiologies of TMD (oral parafunctions) were also assessed. METHODS: The prevalence of malocclusions was correlated in two groups: patients with TMD (case group) and patients without TMD (control group). Malocclusions involving dental care were specified. Parafunctions in the case group were assessed. RESULTS: A statistically significant association between TMD and overbite >4 mm, interferences in laterotrusion, and absence of Angle Class I was shown. A potential deleterious effect of iatrogenic malocclusions was highlighted. CONCLUSION: The multifactorial etiology of TMD was confirmed because an association between TMD and three malocclusions was found, and all case patients had parafunction(s). Current recommendations advising first a reversible treatment, TMD care should start with a behavioral re-education to remove parafunctions. However, it is essential to avoid creating iatrogenic malocclusion during dental care.

Enhancement of the biocompatibility by surface nitriding of a low-modulus titanium alloy for dental implant applications.

To enhance their longevity, dental implants must be highly biocompatible and must have a low elastic modulus close to that of the bone. They must also possess a high superficial hardness and a high corrosion resistance. For these reasons, a recently developed low-modulus Ti-27Nb alloy with nontoxic elements was treated by gas nitriding at high temperature in this study. A very thin nitrided layer of 0.5 µm in thickness followed by an enriched nitrogen zone was observed. Consequently, a very high hardness evaluated at about 1800 HV was obtained in surface, which represents an increase of 4-5 times the hardness of the non-nitrided alloy. This superficial hardness was experimentally observed to decrease up to 800 nm in depth from the surface to the core. The low modulus of Ti-27Nb (evaluated at 55 GPa, which is twice lower than the commercially pure titanium) was not affected by the surface nitriding treatment. A better corrosion resistance was observed and a significant decrease in ion release rates for the nitrided alloy (ion release of 1.41 ng/cm2 compared to the 163.58 ng/cm2 obtained for the commercially pure titanium at pH = 7.48 in artificial Carter-Brugirard saliva). The cytocompatibility was not compromised and the cell viability performed on human osteoblasts, fibroblastic cells, and epithelial cells was enhanced on the nitrided surface in comparison with the non-nitrided surface. These combined properties make the nitrided Ti-27Nb alloy a good candidate for dental implant applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1483-1490, 2019.

[Relations between extraction of wisdom teeth and temporomandibular disorders: a case/control study]. / Relations entre les extractions de dents de sagesse et les dysfonctionnements de l'appareil manducateur : étude cas / témoins.

The aim of this study was to assess the impact of extraction of third molars on the occurrence of temporo-mandibular disorders (TMD). A review of the literature and a case-control study have been conducted. The case-control study compares the frequency of extraction of third molars between the sample with TMD (case) and the sample without TMD (control). The proportion of patients who had undergone extractions of wisdom teeth was higher in the case group than in the control group. The difference was statistically significant when patients had undergone extraction of all four wisdom teeth or when the extraction of four wisdom teeth underwent in one sitting or under general anesthesia. The study of patients in case sample shows that all signs of TMD were more common in patients who had undergone extractions in several sessions and under local anesthesia. The temporomandibular joint sounds are significantly more frequent with local anesthesia. In the case group, 85 to 92% of patients have parafunctions and 5 to 11% have malocclusion. This demonstrates the multifactorial etiology of temporomandibular disorders.

[Relations between orthognathic surgery and temporomandibular disorders: a systematic review]. / Relation entre la chirurgie orthognatique et les dysfonctionnements de l'appareil manducateur. Revue de la littérature.

A painful and dysfunctional temporomandibular joint can be associated with a musculoskeletal anomaly. The multifactorial character of the etiology is now recognized. Among the etiologies, the role of orthognathic surgery is still debated. The analysis of the literature from 2000 to 2011 reveals for most authors a decrease in the frequency and intensity of signs and symptoms after surgery, especially pain and clicking. Risk factors may influence post-surgical results. Studies on patient risk factors such as age, sex, type of dysmorphia are inconclusive. Surgical techniques and the procedure used may have an influence on the development of post-surgical clinical signs and symptoms of temporomandibular disorders.