Le traumatisme occlusal et parodontal : mise au point

Occlusal trauma is the result of excessive occlusal forces that exceeds the repair capabilities of the periodontal attachment apparatus. This expert consensus definition easily clarifies the close links between the dental organ and the periodontium. The controversial nature of occlusal trauma over the time is addressed in this work. The search for a satisfying animal model and the human clinical studies allowed to refine the opinion of the clinicians. Lengthily debated, a body of information asserts the involvement of occlusal trauma in the worsening of periodontal disease. Its clinical diagnosis calls for a bundle of evidence requiring evoking a differential diagnosis. The evolution of concepts around occlusal trauma highlights a combined, multidisciplinary, and innovative approach: the parofunctional approach. This involves first-line occlusal management in parallel with an initial periodontal therapy. Functional optimization with a low additional therapeutic cost for patients is a key element of this type of management. This thesis also highlights the grey areas that persist on the impact of bruxism on periodontium or implant mechanical overloads. A scientific and clinical continuum is needed to improve our practices and to bring a net benefit for patients.Le trauma occlusal est le résultat de forces occlusales excessives qui dépassent les capacités de réparation du système d’attache parodontal. Cette définition de consensus d’experts clarifie aisément les liens étroits entretenus par l’organe dentaire et le parodonte. Le caractère controversé du trauma occlusal à travers le temps est abordé dans ce travail. La recherche d’un modèle animal satisfaisant et les études cliniques humaines ont permis d’affiner l’opinion des cliniciens. Longtemps débattu, un corps d’informations affirme la participation du trauma occlusal dans l’aggravation de la maladie parodontale. Son diagnostic clinique fait appel à un faisceau de preuves nécessitant d’évoquer un diagnostic différentiel. L’évolution des concepts autour du trauma occlusal met en évidence une prise en charge combinée, multidisciplinaire et innovante : l’approche parofonctionnelle. Celle-ci fait intervenir une prise en charge occlusale de première intention en parallèle d’une thérapeutique initiale parodontale. L’optimisation des fonctions avec un surcoût thérapeutique faible pour les patients est un élément clé de ce type de prise en charge. Ce travail de thèse souligne aussi les zones d’ombres qui persistent notamment sur l’impact du bruxisme sur le parodonte, ou encore les surcharges mécaniques implantaires. Un continuum scientifique et clinique s’avère nécessaire afin de poursuivre l’amélioration de nos pratiques et favoriser un bénéfice net pour les patients

Pulp/dentin regeneration and local pathogen killing involve complement system activation

Les lésions carieuses ou les traumatismes physiques profonds aboutissent souvent à une destruction des fibroblastes pulpaires (FP) et des odontoblastes, et provoquent l’activation du Complément. Le rôle du Complément dans la régénération pulpo-dentinaire a été montré avec le fragment C5a, connu pour induire la migration des cellules souches pulpaires (CS). Nous avons montré que le C3a participe à la régénération pulpo-dentinaire. Après un tri cellulaire, nous avons montré l’expression du C3aR sur les CS et les FP en culture, et aussi sur coupes de dents humaines. De plus, les deux types cellulaires prolifèrent en présence de concentrations croissantes de C3a. La migration cellulaire a été évaluée dans des chambres de migration microfluidiques. Les CS sont mobilisées, tandis que les FP sont spécifiquement recrutés par un gradient de C3a. Les complexes d’attaque membranaire (CAM) produits par les FP a été montrée. Nous avons démontré que les FP peuvent détruire les bactéries cariogènes S. mutans et S. sanguis. Les FP ont été incubés avec un milieu contenant du LTA pour simuler une infection bactérienne in vitro. Nous avons montré que les bactéries cariogènes étaient très sensibles aux surnageants des FP stimulés, soulignant un effet létal des CAM. Des co-cultures de fibroblastes pulpaires et de bactéries ont révélé la présence des CAM sur les bactéries. Ces résultats soulignent des rôles inattendus du Complément pendant les étapes précoces de la régénération pulpo-dentinaire et de la défense pulpaire. Ce travail suggère de nouvelles stratégies thérapeutiques, où des molécules du Complément pourront être délivrées localement pour favoriser la régénération pulpo-dentinaireDeep pulp physical injuries or carious lesions often lead to fibroblast cell injury and destruction of the dentin-secreting odontoblasts, and lead to the Complement activation. Its involvement in dentin-pulp regeneration has been shown with C5a fragment, known to induce specific recruitment of DPSC. We show that C3a, is also involved in dentin-pulp regeneration. After cell sorting, we highlighted C3a Receptor expression on pulp fibroblasts and STRO-1-sorted DSPC as well as on human tooth sections in vivo. The effect of C3a on proliferation of DPSCs and pulp fibroblasts was shown with an increased proliferation for both cell types. Cell migration was evaluated using microfluidic chemotaxis chambers. We showed that DPSCs were mobilized but not specifically recruited, while pulp fibroblasts were specifically recruited following a C3a gradient. We demonstrated that pulp fibroblasts can synthesize functional membrane attack complex (MAC) and kill cariogenic bacteria S. mutans and S. sanguinis. To simulate bacterial infection in vitro, pulp fibroblasts were incubated with lipoteichoïc acid (LTA). Agar well diffusion assay showed that bacteria exposed to LTA-conditioned media were highly sensitive, showing lethal effect of MAC. Coculture of pulp fibroblasts and bacteria showed that MAC synthesized by pulp fibroblasts can be directly fixed on cariogenic bacteria, after direct contact with fibroblasts. These results underline unexpected roles of Complement system activation in early events of dentin-pulp regeneration and pulp defense. Our findings suggest new therapeutic strategies, where new agents can deliver specific Complement molecules to enhance dentin-pulp regeneration

Complement C3a Mobilizes Dental Pulp Stem Cells and Specifically Guides Pulp Fibroblast Recruitment

International audienceIntroduction: Complement activation is considered as a major mechanism in innate immunity. Although it is mainly involved in initiating inflammation, recent data reported its involvement in other processes such as tissue regeneration. In the dental pulp, Complement C5a fragment has been shown to be involved in the recruitment of dental pulp stem cells (DPSCs). This study sought to investigate the possible role of C3a, another complement fragment, in the early steps of dentin-pulp regeneration.Methods: Expression of C3a receptor (C3aR) was investigated by immunofluorescence and RT-PCR on cultured pulp fibroblasts, STRO-1-sorted DPSCs as well as on human tooth sections in vivo. The effect of C3a on proliferation of both DPSCs and pulp fibroblasts was investigated by MTT assay. Cell migration under a C3a gradient was investigated using microfluidic chemotaxis chambers.Results: C3aR was expressed in vivo as well as in cultured pulp fibroblasts co-expressing Fibroblast Surface Protein and in DPSCs co-expressing STRO-1. Addition of recombinant C3a induced a significant proliferation of both cell types. When subjected to a C3a gradient, DPSCs were mobilized but not specifically recruited, while pulp fibroblasts were specifically recruited following a C3a gradient.Conclusions: These results provide the first demonstration of C3aR expression in the dental pulp and demonstrate that C3a is involved in increasing DPSCs and fibroblast proliferation, in mobilizing DPSCs and in specifically guiding fibroblast recruitment. This provides an additional link to the tight correlation between inflammation and tissue regeneration

Myelin oligodendrocyte glycoprotein induces incomplete tolerance of CD4 + T cells specific for both a myelin and a neuronal self-antigen in mice

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Complement Activation by Pulp Capping Materials Plays a Significant Role in Both Inflammatory and Pulp Stem Cells' Recruitment

International audienceIntroduction: The role of complement, especially through the C5a fragment, is well-known for the initiation of inflammation. Its involvement in regeneration has been shown more recently by the recruitment of mesenchymal stem cells. C5a can be produced locally by the pulp fibroblasts in response to injury or infection. This work aims to investigate the effect of different pulp capping biomaterials on complement activation and its possible influence on inflammatory and pulp stem cell recruitment. Methods: Conditioned media were prepared from 3 pulp capping biomaterials: Biodentine (Septodont,Saint-Maur-des-Fosses, France), TheraCal (BISCO, Lancon De Provence, France), and Xeno III (Dentsply Sirona, Versaille, France). Injured pulp fibroblasts were cultured with these conditioned media to analyze C5a secretion using an enzyme-linked immunosorbent assay. Dental pulp stem cells (DPSCs) were isolated from human third molar explants by magnetic cell sorting with STRO-1 antibodies. The expression of C5a receptor on DPSCs and inflammatory (THP-1) cells was investigated by immunofluorescence. The migration of both DPSCs and THP-1 cells was studied in Boyden chambers. Results: Pulp fibroblast production of C5a significantly increased when the cells were incubated with TheraCal- and Xeno III conditioned media. The recruitment of cells involved in inflammation (THP-1 cells) was significantly reduced by Biodentine- and TheraCal-conditioned media, whereas the migration of DPSCs was reduced with TheraCal- and Xeno III conditioned media but not with that of Biodentine. The involvement of C5a in cell recruitment is demonstrated with a C5a receptor specific antagonist (W54011). Conclusions: After pulp injury, the pulp capping material affects complement activation and the balance between inflammation and regeneration through a differential recruitment of DPSCs or inflammatory cells

Surgeons’ practice and preferences for the anal fissure treatment: results from an international survey

The best nonoperative or operative anal fissure (AF) treatment is not yet established, and several options have been proposed. Aim is to report the surgeons' practice for the AF treatment. Thirty-four multiple-choice questions were developed. Seven questions were about to participants' demographics and, 27 questions about their clinical practice. Based on the specialty (general surgeon and colorectal surgeon), obtained data were divided and compared between two groups. Five-hundred surgeons were included (321 general and 179 colorectal surgeons). For both groups, duration of symptoms for at least 6 weeks is the most important factor for AF diagnosis (30.6%). Type of AF (acute vs chronic) is the most important factor which guide the therapeutic plan (44.4%). The first treatment of choice for acute AF is ointment application for both groups (59.6%). For the treatment of chronic AF, this data is confirmed by colorectal surgeons (57%), but not by the general surgeons who prefer the lateral internal sphincterotomy (LIS) (31.8%) (p = 0.0001). Botulin toxin injection is most performed by colorectal surgeons (58.7%) in comparison to general surgeons (20.9%) (p = 0.0001). Anal flap is mostly performed by colorectal surgeons (37.4%) in comparison to general surgeons (28.3%) (p = 0.0001). Fissurectomy alone is statistically significantly most performed by general surgeons in comparison to colorectal surgeons (57.9% and 43.6%, respectively) (p = 0.0020). This analysis provides useful information about the clinical practice for the management of a debated topic such as AF treatment. Shared guidelines and consensus especially focused on operative management are required to standardize the treatment and to improve postoperative results