An in vitro analysis model for investigating the staining effect of various chlorhexidine-based mouthwashes

There are different mouthwashes containing chlorhexidine in different concentrations, as well as various excipients. Chlorhexidine induce stains or discoloration in teeth and mucous membranes. The aim of this work was to design a model to reproduce in vitro staining associated with the use of different mouthwashes containing chlorhexidine. We used as substrates of natural teeth and elephant ivory slices. Different incubation baths were conducted over 21 days in culture dishes at 37°C. At the beginning of experiment before incubation (D0) and after 21 days (D21) of incubation with different mouthwashes, pictures of substrates were taken in a standardized manner and an image analysis software was used to analyse and quantify the staining under the various conditions by using the 3 main colours (Red, Green, Blue, RGB). The results of this work demonstrate a very good reproducibility of the protocol, and secondly, a different expression statistically significant of the primary blue colour. We suggest that for a given concentration of chlorhexidine, the staining effects may vary depending on the excipients used. This replicable model, easy to implement over a relatively short duration, can be used for evaluation of existing mouthwashes, and to test the excipients anti discoloration proposed by manufacturers

Postoperative administration of the acetylcholinesterase inhibitor, donepezil, interferes with bone healing and implant osseointegration in a rat model

Donepezil is an acetylcholinesterase inhibitor commonly used to treat mild to moderate Alzheimer’s disease. Its use has been associated with increased bone mass in humans and animals. However, the effect of postoperative administration of donepezil on bone healing remains unknown. Therefore, this study aimed to assess the impact of postoperative injection of donepezil on bone healing, titanium-implant osseointegration, and soft tissue healing. Twenty-two Sprague-Dawley rats were randomly assigned to receive a daily dose of either donepezil (0.6 mg/kg) or saline as a control. In each rat, a uni-cortical defect was created in the right tibia metaphysis and a custom-made titanium implant was placed in the left tibiae. After two weeks, rats were euthanized, and their bones were analysed by Micro-CT and histology. The healing of bone defect and implant osseointegration in the rats treated with donepezil were significantly reduced compared to the saline-treated rats. Histomorphometric analysis showed lower immune cell infiltration in bone defects treated with donepezil compared to the saline-treated defects. On the other hand, the healing time of soft tissue wounds was significantly shorter in donepezil-treated rats compared to the controls. In conclusion, short-term administration of donepezil hinders bone healing whereas enhancing soft tissue healing

Differences in platelet-rich plasma composition influence bone healing

Aim: Platelet-rich plasma (PRP) is an autologous blood-derived material that has been used to enhance bone regeneration. Clinical studies, however, reported inconsistent outcomes. This study aimed to assess the effect of changes in leucocyte and PRP (L-PRP) composition on bone defect healing. Materials and Methods: L-PRPs were prepared using different centrifugation methods and their regenerative potential was assessed in an in-vivo rat model. Bilateral critical-size tibial bone defects were created and filled with single-spin L-PRP, double-spin L-PRP, or filtered L-PRP. Empty defects and defects treated with collagen scaffolds served as controls. Rats were euthanized after 2 weeks, and their tibias were collected and analysed using micro-CT and histology. Results: Double-spin L-PRP contained higher concentrations of platelets than singlespin L-PRP and filtered L-PRP. Filtration of single-spin L-PRP resulted in lower concentrations of minerals and metabolites. In vivo, double-spin L-PRP improved bone healing by significantly reducing the size of bone defects (1.08 ± 0.2 mm3 ) compared to single-spin L-PRP (1.42 ± 0.27 mm3 ) or filtered L-PRP (1.38 ± 0.28 mm3 ). There were fewer mast cells, lymphocytes, and macrophages in defects treated with double-spin L-PRP than in those treated with single-spin or filtered L-PRP. Conclusion: The preparation method of L-PRP affects their composition and potential to regenerate bone

Le Cracked Tooth Syndrome

Le Cracked Tooth Syndrome (CTS) a été évoqué pour la première fois par Cameron en 1964, pour décrire la présence d'une fêlure, visible ou non, sur une dent postérieure vitale, progressant dans la dentine, pour atteindre parfois la pulpe et le parodonte. Ce syndrome, peu connu, est délicat à diagnostiquer et souvent mal traité. Les cas de CTS sont néanmoins en augmentation. Ce travail de thèse permet de mieux appréhender les mécanismes de survenue du CTS pour pouvoir proposer une prise en charge adaptée. Pour cela, la classification des fêlures est rappelée, les étiologies et les facteurs de risque du CTS sont décrits, la symptomatologie et le diagnostic des CTS sont développés. Enfin, les traitements des CTS et les moyens de prévention envisageables sont proposés. Un arbre décisionnel a été conçu à l'issue de ce travail pour constituer une aide à la prise de décision clinique, face à une suspicion de CTS.NANTES-BU Médecine pharmacie (441092101) / SudocNANTES-Bib.Odontologie (441092219) / SudocSudocFranceF

Extracellular Matrices for Bone Regeneration: A Literature Review

International audienceThe gold standard material for bone regeneration is still autologous bone, a mesenchymal tissue that consists mainly of extracellular matrix (ECM) (90% v/v) and little cellular content (10% v/v). However, the fact that decellularized allogenic bone grafts often present a clinical performance comparable to autologous bone grafts demonstrates the crucial role of ECM in bone regeneration. For long, the mechanism by which bone allografts function was not clear, but recent research has unveiled many unique characteristics of ECM that seem to play a key role in tissue regeneration. This is further confirmed by the fact that synthetic biomaterials with composition and properties resembling bone ECM present excellent bone regeneration properties. In this context, ECM molecules such as glycosaminoglycans (GAGs) and self-assembly peptides (SAPs) can improve the performance of bone regeneration biomaterials. Moreover, decellularized ECM derived either from native tissues such as bone, cartilage, skin, and tooth germs or from cells such as osteoblasts, chondrocytes, and stem cells has shown promising results in bone regeneration applications. Understanding the role of ECM in bone regeneration is crucial for the development of the next generation of biomaterials for bone tissue engineering. In this sense, this review addresses the state-of-the-art on this subject matter

Platelet concentrates for bone regeneration: Current evidence and future challenges

International audienceActivated platelet concentrates are autologous blood preparations containing supraphysiological concentration of platelets. Platelet concentrates are commonly used for bone regeneration purposes based on the fact that growth factors released from activated platelets alpha granules have osteoinductive effects on bone cells. Although most preclinical and clinical studies show that platelet concentrates improve the outcomes of bone regeneration procedures, some studies reported conflicting results and even negative effects on bone healing. Several confounding parameters have been suggested as possible reasons for such inconsistencies (i.e. preparation and activation methods). However, heterogeneity in clinical studies makes drawing evidence-based conclusions difficult. On the other hand, recent findings show that the constituents of platelets dense granules (i.e. serotonin, ATP, Ca2+) have potential inhibitory effects on bone metabolism. Accordingly, we suggest that a partial explanation for the conflicting results could be the potential negative effects that dense granules may have on bone healing

Periodontal pockets: a potential reservoir for SARS-CoV-2?

Periodontal pockets are the major clinical manifestation of Periodontitis, a chronic inflammatory oral disease affecting the teeth-supporting tissues and has high prevalence in the adult population. Periodontal pockets are ideal environments for subgingival bacterial biofilms, that interact with the supragingival oral cavity, mucosal tissues of the pocket and a peripheral circulatory system. Periodontal pockets have been found to harbor viral species such as the Herpes simplex viruses’ family. Recently, the SARS-CoV-2 has gained major interest of the scientific/medical community as it caused a global pandemic (Covid-19) and paralyzed the globe with high figures of infected people worldwide. This virus behavior is still partially understood, and by analyzing some of its features we hypothesized that periodontal pocket could be a favorable anatomical niche for the virus and thus acting as a reservoir for SARS-CoV-

Periodontal pockets: A potential reservoir for SARS-CoV-2?

International audiencePeriodontal pockets are the major clinical manifestation of Periodontitis, a chronic inflammatory oral disease affecting the teeth-supporting tissues and has high prevalence in the adult population. Periodontal pockets are ideal environments for subgingival bacterial biofilms, that interact with the supragingival oral cavity, mucosal tissues of the pocket and a peripheral circulatory system. Periodontal pockets have been found to harbor viral species such as the Herpes simplex viruses’ family. Recently, the SARS-CoV-2 has gained major interest of the scientific/medical community as it caused a global pandemic (Covid-19) and paralyzed the globe with high figures of infected people worldwide. This virus behavior is still partially understood, and by analyzing some of its features we hypothesized that periodontal pocket could be a favorable anatomical niche for the virus and thus acting as a reservoir for SARS-CoV-2

Photodynamic Therapy for Peri-Implant Diseases

Peri-implant diseases are frequently presented in patients with dental implants. This category of inflammatory infections includes peri-implant mucositis and peri-implantitis that are primarily caused by the oral bacteria that colonize the implant and the supporting soft and hard tissues. Other factors also contribute to the pathogenesis of peri-implant diseases. Based on established microbial etiology, mechanical debridement has been the standard management approach for peri-implant diseases. To enhance the improvement of therapeutic outcomes, adjunctive treatment in the form of antibiotics, probiotics, lasers, etc. have been reported in the literature. Recently, the use of photodynamic therapy (PDT)/antimicrobial photodynamic therapy (aPDT) centered on the premise that a photoactive substance offers benefits in the resolution of peri-implant diseases has gained attention. Herein, the reported role of PDT in peri-implant diseases, as well as existing observations and opinions regarding PDT, are discussed