Assessment of the quality of oral biopsy procedure videos shared on YouTube

OBJECTIVE

The aim of this study was to assess the quality of free-to-access videos on oral biopsy procedures on the YouTube platform.

MATERIALS AND METHODS

We conducted a search on YouTube using the term "oral biopsy" and selected the first 100 videos in order of relevance. The following exclusion criteria were applied: language other than English, videos that did not cover oral biopsy techniques, videos on nonhuman specimens, postoperative instructions, personal experiences, exfoliative cytology, or "brush biopsy." Forty-seven selected videos were classified based on their duration, country of origin, date of upload to the system, author, information source and number of views, and likes and dislikes. Video quality was analyzed using DISCERN, the Global Quality Scale (GQS), and the Video Information and Quality Index (VIQI).

RESULTS

The majority (78.7%) of analyzed videos were uploaded by dentists, originating from India (48.9%), with a mean duration of 11.8 min (SD, 20.4), with 104.5 likes (SD, 186.4) and 7.1 dislikes (SD, 10.55). The mean values for DISCERN, GQS, and VIQI were 1.3 (SD, 0.52), 2.1 (SD, 1.04), and 9.62 (SD, 1.69), respectively.

CONCLUSION

The majority of videos on oral biopsy published on YouTube are of low quality.

French guidelines for the management of oral lichen planus (excluding pharmacological therapy)

INTRODUCTION

Oral lichen is a chronic inflammatory disease for which diagnostic management and follow-up are heterogeneous given the absence of specific guidelines in France. Our objective was to develop French multidisciplinary guidelines for the management of oral lichen.

MATERIALS AND METHODS

Working groups from the Groupe d'Etude de la Muqueuse Buccale (GEMUB) formulated a list of research questions and the corresponding recommendations according to the "formal consensus" method for developing practice guidelines. These recommendations were submitted to a group of experts and the degree of agreement for each recommendation was assessed by a scoring group.

RESULTS

Twenty-two research questions, divided into 3 themes (nosological classification and initial assessment, induced oral lichenoid lesions, and follow-up) resulted in 22 recommendations. Initial biopsy for histology is recommended in the absence of reticulated lesions. Biopsy for direct immunofluorescence is recommended for ulcerated, erosive, bullous types and for diffuse erythematous gingivitis. Management should include a periodontal and dental check-up, and investigation for extra-oral lesions. Hepatitis C testing is recommended only if risk factors are present. Definitions, triggering factors and the management of "induced oral lichenoid lesions" were clarified. Oral lichen must be monitored by a practitioner familiar with the disease at least once a year, using objective tools.

CONCLUSION

This formalised consensus of multidisciplinary experts provides clinical practice guidelines on the management and monitoring of oral lichen.

Cell-assembled extracellular matrix (CAM): a human biopaper for the biofabrication of pre-vascularized tissues able to connect to the host circulationin vivo

When considering regenerative approaches, the efficient creation of a functional vasculature, that can support the metabolic needs of bioengineered tissues, is essential for their survival after implantation. However, it is widely recognized that the post-implantation microenvironment of the engineered tissues is often hypoxic due to insufficient vascularization, resulting in ischemia injury and necrosis. This is one of the main limitations of current tissue engineering applications aiming at replacing significant tissue volumes. Here, we have explored the use of a new biomaterial, the cell-assembled extracellular matrix (CAM), as a biopaper to biofabricate a vascular system. CAM sheets are a unique, fully biological and fully human material that has already shown stable long-term implantation in humans. We demonstrated, for the first time, the use of this unprocessed human ECM as a microperforated biopaper. Using microvalve dispensing bioprinting, concentrated human endothelial cells (30 millions ml^-1) were deposited in a controlled geometry in CAM sheets and cocultured with HSFs. Following multilayer assembly, thick ECM-based constructs fused and supported the survival and maturation of capillary-like structures for up to 26 d of culture. Following 3 weeks of subcutaneous implantation in a mice model, constructs showed limited degradative response and the pre-formed vasculature successfully connected with the host circulatory system to establish active perfusion.This mechanically resilient tissue equivalent has great potential for the creation of more complex implantable tissues, where rapid anastomosis is sine qua non for cell survival and efficient tissue integration.

Topical rapamycin versus betamethasone dipropionate ointment for treating oral erosive lichen planus: a randomized, double-blind, controlled study

BACKGROUND

Although superpotent topical corticosteroids are the first-line treatment for oral erosive lichen planus (OELP), topical rapamycin was found efficient in a previous case series.

OBJECTIVES

To compare the efficacy and safety of topical rapamycin and betamethasone dipropionate ointment for OELP in a randomized, double-blind trial.

METHODS

Patients were randomized to receive treatment with betamethasone dipropionate ointment 0.05% in Orabase^® or topical rapamycin solution (1 mg/mL) on lesions twice daily for 3 months, followed by 3 months of observation. The primary outcome was clinical remission after 3 months of treatment. Secondary outcomes were clinical remission after 1 and 2 months, reduced oral pain and reduced impact on food intake after 3 months, clinical recurrence after treatment withdrawal, and adverse events.

RESULTS

During a 4-year period, 76 patients were randomized and 75 received treatment (rapamycin, n = 39; betamethasone, n = 36). At 3 months, 39.4% of patients with betamethasone and 27.3% with rapamycin showed clinical remission (odds ratio 0.68, 95% CI [0.24; 1.89]; P = 0.46). Rates of remission after 1 and 2 months, reduction in pain and impact on food intake after 3 months, were higher with betamethasone than rapamycin. Recurrence of oral erosions was similar between groups. Adverse events occurred in 43.6% of patients with rapamycin (mostly burning sensation, impaired taste) and 27.8% with betamethasone (mostly oral candidiasis).

CONCLUSION

Although the study was limited by insufficient recruitment, we did not find any superiority of topical rapamycin over betamethasone dipropionate ointment for OELP. Given the rapid remission and pain improvement in the betamethasone group, it appears that superpotent topical corticosteroids should remain the first-line treatment for OELP.

What is the benefit of using amniotic membrane in oral surgery? A comprehensive review of clinical studies

OBJECTIVES

Since its first use for the reconstruction of tissue defects in the oral cavity in 1985, human amniotic membrane (hAM) has been widely studied in the field of oral surgery. Despite the growing number of publications in this field, there is no systematic review or meta-analysis concerning its clinical applications, outcome assessments, and relevance in oral surgery. The aim of this review is to provide a thorough understanding of the potential use of hAM for soft and hard tissue reconstruction in the oral cavity.

MATERIALS AND METHODS

A systematic electronic and a manual literature search of the MEDLINE-PubMed database and Scopus database was completed. Patient, Intervention, Comparison and Outcomes (PICO) technique was used to select the relevant articles to meet the objective. Studies using hAM for oral reconstruction, and conducted on human subjects, were included in this survey.

RESULTS

A total of 17 articles were analyzed. Five areas of interest were identified as potential clinical application: periodontal surgery, cleft palate and tumor reconstruction, prosthodontics and peri-implant surgery. Overall, periodontal surgery was the only discipline to assess the efficacy of hAM with randomized clinical trials. The wide variability of preservation methods of hAM and the lack of objective measurements were observed in this study.

CONCLUSION

hAM is already used in the field of oral surgery. Despite this, there is weak clinical evidence demonstrating convincingly the benefit of hAM in this area compared to standard surgery.

CLINICAL RELEVANCE

Several studies now suggest the interest of hAM for periodontal tissue repair. Due to its biological and mechanical properties, hAM seems to be a promising treatment for wound healing in various areas of oral reconstruction. However, further randomized clinical trials are needed to confirm these preliminary results.

Outcome of CO2 laser vaporization for oral potentially malignant disorders treatment

Background

Oral cancer is a public health issue worldwide. Oral potentially malignant disorders (OMPDs) are lesions of the oral mucosa that are predisposed to malignant transformation. The mainstay of OMPDs treatment around the world is now the carbon dioxide (CO2) laser but the reported recurrence and malignant transformation rates vary widely in the literature. We aimed to estimate the recurrence and the malignant transformation rates of OPMDs treated with CO2 laser at the University Hospital of Bordeaux, in France, from 2010 to 2014, and to identify associated factors with recurrence or malignant transformation.

Material and Methods

We conducted a retrospective study in patients with a minimum follow-up of 12 months. Collected variables included characteristics of the patients (gender, age, alcohol and tobacco consumption, previous diagnosis of graft-versus-host disease, previous treatments for OPMD or for upper aerodigestive tract cancers and human immunodeficiency virus infection), characteristics of the lesions (form, colour, size, location, degree of dysplasia), laser treatment outcome (complications, recurrence, malignant transformation).

Results

Twenty-five patients were included. Mean follow-up was 28.9 months. Recurrence was observed in 11 patients (44%). Annual recurrence rate was 18.3% and annual malignant transformation rate was 1.7%. Hyperplasia without dysplasia was the only factor found to be statistically associated with recurrence.

Conclusions

Our results suggest that OMPDs treated by CO2 laser vaporization have high recurrence rates, particularly those presenting hyperplasia. A standardized definition of recurrence would be necessary for inter-study comparisons. Long-term follow-up is recommended in order to detect and treat squamous cell carcinoma in its early stages.

Key words:CO2 lasers, precancerous conditions, malignant transformation, oral cancer, recurrence.

[Reached multifocal secondary syphilis: A case presentation]

INTRODUCTION

Syphilis is a sexually transmitted infection (STI) related to Treponema pallidum. Secondary syphilis is the blood-borne systemic spread of Treponema.

OBSERVATION

We report the case of secondary syphilis in a patient without risk of STIs factor. The clinical picture began with a genital affection followed by oral erosions and ulcers and an anterior and then posterior uveitis. Serology established the diagnosis and intravenous penicillin G treatment allowed for healing.

DISCUSSION

Called the "great pretender" because of its clinical polymorphism, secondary syphilis can lead to formidable neurological and ophthalmological complications. Serological diagnosis is based on the use of treponemal and a nontreponemal tests. Penicillin G remains the treatment of choice and must be adapted according to the clinical damage.

[Oral hairy leukoplakia induced by topical steroids]

BACKGROUND

Oral hairy leukoplakia (OHL) is an EBV-associated condition of the oral mucosa, which is often painless. It is found predominantly in HIV-positive patients and is considered a clinical indicator of immunosuppression. OHL has rarely been described in HIV-negative patients, being found most often in association with iatrogenic immunosuppression. OHL induced by topical steroids remains extremely rare.

PATIENTS AND METHODS

An 81-year-old HIV-negative woman, treated for 3 months with topical steroids for oral lichen planus, developed an asymptomatic white, corrugated, non-removable plaque with vertical folds on the lateral edge of the tongue. Associated oral candidiasis was noted. Based upon histological findings and in situ hybridisation showing numerous EBV-infected epithelial cells, a diagnosis of oral hairy leucoplakia was made.

DISCUSSION AND CONCLUSION

To our knowledge, we report herein only the second recorded case of OHL induced strictly by topical steroids. Self-medication and poor adherence to dosage recommendations were noted in the patient's medical history. Physicians must be aware of the rare but nevertheless possible adverse events associated with topical steroid use, particularly when such medication is prescribed over a long period for inflammatory diseases of the oral mucosa.

[Induced membrane technique in oral & maxillofacial reconstruction]

Maxillofacial defects reconstruction represents a formidable challenge to achieve both functional and aesthetic goals. To succeed, numerous parameters must be taken into account: patient's general conditions, defect's location, width and type of the defect and eventual donor sites which can provide the tissues. Routine reconstructions include bone transplantation (autologous, homologous or heterologous), implantation of biomaterials and osteogenic distraction. The advantages of these techniques are evident, but they are usually limited by their complexity in patients with bad general health. The technique of induced membranes needs to be more known in maxillofacial surgery.

Magnetic resonance imaging tracking of human adipose derived stromal cells within three-dimensional scaffolds for bone tissue engineering

For bone tissue engineering, human Adipose Derived Stem Cells (hADSCs) are proposed to be associated with a scaffold for promoting bone regeneration. After implantation, cellularised scaffolds require a non-invasive method for monitoring their fate in vivo. The purpose of this study was to use Magnetic Resonance Imaging (MRI)-based tracking of these cells, labelled with magnetic agents for in vivo longitudinal assessment. hADSCs were isolated from adipose tissue and labelled with USPIO-rhodamine (Ultrasmall SuperParamagnetic Iron Oxide). USPIO internalisation, absence of toxicity towards hADSCs, and osteogenic differentiation of the labelled cells were evaluated in standard culture conditions. Labelled cells were then seeded within a 3D porous polysaccharide-based scaffold and imaged in vitro using fluorescence microscopy and MRI. Cellularised scaffolds were implanted subcutaneously in nude mice and MRI analyses were performed from 1 to 28 d after implantation. In vitro, no effect of USPIO labelling on cell viability and osteogenic differentiation was found. USPIO were efficiently internalised by hADSCs and generated a high T2* contrast. In vivo MRI revealed that hADSCs remain detectable until 28 d after implantation and could migrate from the scaffold and colonise the area around it. These data suggested that this scaffold might behave as a cell carrier capable of both holding a cell fraction and delivering cells to the site of implantation. In addition, the present findings evidenced that MRI is a reliable technique to validate cell-seeding procedures in 3D porous scaffolds, and to assess the fate of hADSCs transplanted in vivo.

[Autofluorescence for the detection of potentially malignant and malignant lesions of the oral cavity lining]

INTRODUCTION

The sensitivity of visual examination for the diagnosis of oral cancers is estimated at 85% and its specificity at 97%. However, it is likely that numerous lesions remain undetected. The objective of this article was to review literature on the contribution of tissular autofluorescence to detect potentially malignant and malignant lesions of the oral cavity.

MATERIAL AND METHOD

The Medline database was consulted using the following keywords: fluorescence and cancer; autofluorescence and cancer; fluorescence and oral cancer; autofluorescence and oral cancer; Velscope(®) and oral cancer. Only original articles and clinical case reports on the oral cavity published in English since 1999 were considered.

RESULTS

Twenty-three publications were analyzed. Twelve studies concerned spectroscopy and 14 direct autofluorescence. The specificity of AF ranged between 75 and 100% in spectroscopy and between 39 and 100% in direct vision. The sensibility of the AF varied between 78 and 100% in spectroscopy and between 50 and 100% in direct vision.

DISCUSSION

The variability of results may be explained by selection bias. The main contribution of fluorescence is to highlight oral mucous membrane lesions and to help physicians to better locate them. The lack of AF specificity supports the contribution of histological examination which remains the reference examination for the diagnosis of potentially malignant lesions and cancers of the oral cavity.

[Resorption of cartilage grafts in rhinoplasty: fundamental basis]

Resorption of the autologous cartilage graft of the nasal dorsum is a problem which concerns all rhinoplasticians. Their rate of resorption is estimated between 20 to 30% of the graft volume and can occur with no means of prevention from the side of the surgeon. The goal of this article is to highlight, through a short review of the literature, the current data regarding the composition of the septal cartilage, its healing process and the progress made in cartilaginous tissue engineering to adapt our surgical technique. Cartilaginous tissue engineering does not yet have the abilities to provide a replacement septal cartilage with the same molecular composition, the same mechanical properties and devoid of volume loss after implantation and in spite of a certain progress, autologous cartilage grafts are still making the headlines. However to avoid the resorption of the latter and to preserve their volume, it seems necessary to avoid crushing them so as not to compromise chondrocyte viability and proliferation. Cutting-out millimeter-length dices seems more adapted to preserve cellular viability but remains insufficient because of the low healing capacities of the cartilage. Diced-cartilage wrapped with connective tissue seems an elegant and efficient solution over the long run to safeguard their volume and to harmonize contours and irregularities of the dorsum.

Cyclo-DfKRG peptide modulates in vitro and in vivo behavior of human osteoprogenitor cells on titanium alloys

The first aim of the present study was to investigate the capacity of a cyclo-DfKRG-coated hydroxyapatite-titanium alloy (Ti-HA-RGD) to activate in vitro human osteoprogenitor cells adhesion and differentiation. The second purpose was to examine in vivo the role of a autologous cell seeding on cyclo-DfKRG-functionalized materials to provide bone repair after implantation in femoral condyle of rabbits. Our in vitro results have demonstrated that both titanium alloy functionalized with hydroxyapatite (Ti-HA-RGD and Ti-HA) contributed to higher cell adhesion than titanium alloy alone respectively 85 and 55% vs 15% compared to tissue culture polystyrene after one hour of cell seeding. As for differentiation, after 3 days of culture, Ti-HA presented the highest increase of ALP mRNA of all surfaces studied. Ti-HA-RGD showed an intermediate value about half as high as Ti-HA. Moreover after 3 days, both Ti-HA and Ti-HA-RGD surfaces showed the highest increase of cbfa1 mRNA expression. Two weeks following implantation, in vivo findings revealed that percentage of lacunae contact observed with pre-cellularized Ti-HA-RGD samples remains significantly lower than with Ti-HA group (10.5+/-9.6 % vs 33.7+/-11.5 %, P<0.03). Meanwhile, RGD peptide coating had no significant additional effect on the bone implant contact and area. Moreover, histomorphometry analysis revealed that implantation of pre-cellularized RGD coated materials with ROP cells increased significantly peri-implant fibrous area (24+/-11.6% vs 3+/-1.7% for Ti-HA-RGD, P<0.02). RGD coatings demonstrated osteoblastic adhesion, differentiation and in vivo bone regeneration at most equivalent to HA coatings.

[Multiple verruciform xanthomas of the oral mucosa associated with graft versus host disease]

BACKGROUND

Verruciform xanthoma is an uncommon lesion that occurs primarily on the mucous membranes and more rarely on the skin. A few authors have reported the extremely rare occurrence of multiple lesions. Triggering or enhancing factors have been occasionally described such as an underlying immunosuppression or associated inflammatory mucous or skin diseases. We report, to the best of our knowledge, the first case report of multiple verruciform xanthomas of the oral mucosa in a patient with graft-versus-host disease with specific oral lesions.

CASE REPORT

A 57 year-old man presented with an 8-year history of chronic myeloid leukemia. He was considered in complete remission for leukemia after allogenic bone marrow transplantation. Nevertheless, he was still treated with immunosuppressive drugs for oral and cutaneous lesions of chronic graft-versus-host disease. In this context, the patient presented two symmetric lesions of the gingiva. These lesions had progressed over several months. The clinical presentation was similar, with a yellowish and verrucous aspect and a sessile base. Histologic and immunohistochemical analysis led to the diagnosis of multiple verruciform xanthomas.

DISCUSSION

The occurrence of multiple lesions of this rare tumour in our patient was probably not fortuitous. Immunosuppression associated with oral chronic inflammatory lesions are certainly involved in the pathogenesis of these two verruciform xanthomas, for example following degeneration of epithelial cells after local chronic irritation and/or reduction of Langerhans cells. Systematic research of enhancing or triggering factors seems essential in verruciform xanthoma.

[Persistant mucosal ulcerations: a rare complication of toxic epidermal necrolysis]

INTRODUCTION

Sequels can be observed in toxic epidermal necrolysis. Persistence of mucosal ulcerations is not a classical complication of this disease. We describe two case reports of mucous membrane ulcerations (oral and genital) which have remained many months after the acute phase of toxic epidermal necrolysis.

CASE REPORTS

Case 1. A little girl, 9 years old, was referred for a chronic and painful ulceration of the vulva that had appeared 9 months earlier during a toxic epidermal necrolysis. She presented a clearly crircumscribed vestibular ulceration. The mucosal biopsy was refused by the family. The genital erosion persisted more than one year after the acute phase. Case 2. A 73 year-old man was referred for a persistent and clearly circumscribed lingual ulceration, 9 cm in diameter. This chronic ulceration had appeared 3 months earlier, during the acute phase of a toxic epidermal necrolysis. The skin biopsy specimen, with histologic and direct immunofluorescence analysis, did not disclose any specific anomalies. After a period of clinical observation, intralesional injections of corticosteroids were decided and ulceration progressively decreased in 13 months.

DISCUSSION

Complications of toxic epidermal necrolysis mainly occur at the acute phase. The most well documented sequelae are ophthalmological lesions. The most frequent cutaneous sequelae are cutaneous pigmentary changes and nail dystrophy. We report two observations of persistent mucous membrane erosions many months after the acute phase of toxic epidermal necrolysis. The pathophysiology of this complication, is rarely described and still remains unclear.

Development of a resorbable macroporous cellulosic material used as hemostatic in an osseous environment

The control of bleeding is a frequently encountered therapeutic problem, particularly during dental surgery. The most efficient substances used to resolve this problem are not risk-free because of their animal or human origins, so cellulosic materials are potentially of interest. The aim of this study was to develop a resorbable macroporous cellulosic material for use as a resorbable hemostatic agent in bone sites. The degradation and the cytocompatibility of the cellulosic material versus controls were evaluated and its behaviour in vivo was studied. An original process using calcium carbonate powder as inverse matrix was used to develop a macroporous material. In order to predegrade the cellulosic material for hemostatic use, oxidation was performed with periodate. A dialdehyde component unstable at physiological pH was thus obtained. The material was found to have cytotoxicity, biocompatibility, and resorption properties similar to control but its hemostatic power was higher.

Mucosal Pigmentation after Oral Lichen planus Treatment with Topical Tacrolimus

Erosive oral lichen planus (OLP) is a painful chronic inflammatory disease that is sometimes resistant to systemic or topical therapies. Topical steroids remain the mainstay of therapy, but topical tacrolimus has recently been used to treat OLP resistant to topical corticosteroids. Topical tacrolimus appears as an effective and safe treatment of symptomatic OLP. We report the first histopathologically documented case of oral mucosa pigmentation after OLP treatment with topical tacrolimus. The relation between tacrolimus treatment and staining was suggested by the appearance of pigmentation during topical tacrolimus treatment and its clinical disappearance when treatment was stopped. Histopathology showed an increase in melanocyte numbers and melanogenesis.

[Pinctada margaritifera nacre (mother-of-pearl): physico-chemical and biomechanical properties, and in vitro cytocompatibility]

PURPOSE OF THE STUDY

Pinctada maxima nacre (mother-of-pearl) has been recently proposed as a bone substitute. The purpose of this work was to assess the in vitro cytocompatibility of Pinctada margaritifera nacre and its physico-chemical and biomechanical properties.

MATERIAL AND METHODS

The cytocompatiblity was assessed in contact with human osteoprogenetic cells. Attachment was measured at one hour and three hours by determining N-acetyl-beta-D-hexosaminidase activity. Proliferation was monitored by measuring metabolic activity with the MTT test. Cell morphology was studied under scanning electron microscopy and cell differentiation was assessed by immunocytochemistry monitoring of the synthesis of type I collagen and osteocalcin. Diffraction x-ray and scanning electron microscopy was used to study the physico-chemical structure. Two samples taken from the inner part of the shell and two other samples from the outer part of the shell were tested for resistance under compression and to calculate the Young module.

RESULTS

The results showed that osteoprogenetic cells attached to the nacre (2/3 of the plastic control), proliferated according to a standard pattern (increased metabolic activity followed by a plateau then decreased activity), synthetized type I collagen and osteocalcin, and presented a morphology analogous to control cells cultured on the plastic culture wells. The diffraction spectrum of the crystalline structure corresponded to crystallized calcium carbonate in the form of calcite (CaCO(3)) for the outer part and in the form of aragonite for the inner part. The Young module was 46.1 Gpa and resistance to rupture was 185 Mpa.

CONCLUSION

Pinctada margaritifera nacre is cytocompatible in vitro with mechanical properties very similar to cortical bone.

Cellulose phosphates as biomaterials. In vivo biocompatibility studies

Femoral implantation of regenerated cellulose hydrogels revealed their biocompatibility, but a complete osseointegration could not be observed. Phosphorylation was therefore envisaged as the means to enhance cellulose bioactivity. In vitro studies showed that regenerated cellulose hydrogels promote bone cells attachment and proliferation but do not mineralize in acellular simulated physiological conditions. On the contrary, phosphorylated cellulose has shown an opposite behavior, by inducing the formation of a calcium phosphate layer in simulated physiological conditions, but behaving as a poor substrate for bone cells attachment and proliferation. In order to investigate the in vivo behavior of these materials, and assess the influence of mineralization induction ability vs. bone cells compatibility, unmodified and phosphorylated cellulose hydrogels were implanted in rabbits for a maximum period of 6 months and bone regeneration was investigated. Despite the difficulties arising from the retraction of cellulose hydrogels upon dehydration during the preparation of retrieved implants, histological observations showed no inflammatory response after implantation, with bone intra-spongious regeneration of cells and the integration of the unmodified as well as the phosphorylated cellulose implants. After a maximum implantation period of 6 months, histological observations, histomorphometry and the measurement of the amount of 45Ca incorporated in the surrounding tissue indicated a slightly better osseointegration of phosphorylated cellulose, although no significant differences between the two materials were found.

Cytocompatibility study of organic matrix extracted from Caribbean coral porites astroides

Since 1980, natural coral exoskeleton has been widely used as bone graft substitute. Despite numerous in vitro and in vivo studies. there is still a lack of knowledge concerning the organic matrix associated with coral exoskeleton (COM). In fact, some surgical interventions have failed and this has sometimes been attributed to the exoskeleton organic matrix. For others, only amino acids are present in the matrix after coral preparation for clinical use. The objective of this study was to extract the exoskeleton organic matrix to carry out biochemical analysis and study its specific cytocompatibility. Demineralized bone powder (DBP) was used as control. A decalcification process was used to extract COM and DBP. Protein, carbohydrate and glycosaminoglycan analysis was carried out in DBP and COM using classical staining methods. Human bone marrow cells were cultured in the presence of 20, 40, 80, 160 microg of COM or DBP for 24, 48 and 72 h. The methods used to analyze COM and DBP effects were scanning electron microscopy immunocytochemistry, manual cell count, and cyto-compatibility assay (Neutral red and MTT tests). Results showed that in spite of treating coral before clinical use, a COM was present in which GAG, protein and carbohydrate were found. The in vitro cytocompatibility of COM was confirmed for 20 and 40 microg values but was less pronounced for 80 and 160 microg levels.

Evaluation of proliferation and protein expression of human bone marrow cells cultured on coral crystallized in the aragonite of calcite form

The two crystalline forms of CaCO3, aragonite (from natural coral) and calcite (from natural limestone), have been used with success as bone graft substitutes. However, natural coral transformed into calcite by heating has never been tested. The objective of this work was to study the proliferation and alkaline phosphatase, osteonectin, and osteocalcin expression of human bone marrow cells cultured on CaCO3 crystallized both in the aragonite form (natural coral) and in the calcite form (natural coral modified by heating). The methods used to characterize calcite obtained from the coral were volumic porosimetry, scanning electron microscopy (SEM) and X-ray diffraction. Cell colonization of the material was assessed by SEM performed on days 1, 7, 20, and 30 and [3H]thymidine incorporation was performed on days 3, 7, 12, 18, 25, and 32. Phenotypic expression was assessed by using in situ cytochemistry (alkaline phosphatase), immunocytochemistry (osteonectin and osteocalcin), and hybridization (osteocalcin, beta-actin, and alkaline phosphatase mRNA). Results showed the transformation of aragonite into calcite after heating, the conservation of macroporosity, and a modification of the surface. Calcite appeared to have a smoother and more uniform surface than aragonite crystals. As for [3H]thymidine there was an increase incorporation from days 3 to 18, a stabilization from days 18 to 25, and a decrease from days 25 to 32. After 20 days of culture, immunological studies using monoclonal antibodies to osteocalcin, osteonectin, cytochemical analysis of alkaline phosphatase activity, and in situ hybridization using osteocalcin, beta-actin, and alkaline phosphatase cDNA indicated that the cells had not lost their osteoblastic phenotype. These experiments demonstrate that coral crystallized in the aragonite or calcite form present a similar degree of specific cytocompatibility.

"In vitro" dissolution of coral in peritoneal or fibroblast cell cultures

Previous studies have shown that in vivo coral resorption involves a biphasic process: First, the edges of the coral block become powdery, then extracellular fluid and phagocytosis contribute to the dissolution of the crystals. The authors examined some types of cells that could be involved in phagocytosis, particularly the ability of both dermal fibroblasts and mouse-resident peritoneal cells to phagocytose and dissolve coral powder "in vitro". Radioactive coral was incubated for 24, 48, or 72 hrs with cells in the presence or absence of cytochalasin B (a phagocytic inhibitor) or chloroquine (a lysosomotropic agent). Furthermore, to specify the role of crystal cell contacts in the solubilization process, they incubated radioactive coral in conditioned media (obtained from two-day human fibroblastic or macrophagic cell culture in the presence or absence of non-radioactive coral) or at a distance from the cells using culture inserts. Measurements of the radioactivity in the different supernatants were performed. Transmission electron microscopy was carried out on the cells cultivated in the presence or absence of radioactive coral. The data suggest that both fibroblasts and macrophages dissolve the coral, and that the intracellular degradation in phagolysosomes is one of the mechanisms explaining coral powder dissolution.

Influence of the structure of three corals on their resorption kinetics

The aim of this study was to investigate the influence of the structure of corals on their resorption kinetics after implantation in subcutaneous areas. Three types of coral (Porites astreoides, Montastrea annularis and Dichocoenia stokesi) identical in composition but different in structure were implanted for periods of 1 and 2 months in subcutaneous sites in OF1 mice. The resorption of the implants was studied by means of qualitative (histology, scanning electron microscopy, fluorochrome labelling method) and quantitative approaches (gravimetric method). The results of the qualitative study revealed a process of irregular deterioration of the coral, linked to the detachment of crystals at the surface of the implant. The results of the quantitative study showed that the speed of resorption increases with the implantation time and the open porosity of the coral. These reactions are explained by the increase of the surface exchange area in contact with factors responsible for resorption: biological medium and cells. When considering the choice of coral as a bone substitute, these factors must be taken into account to allow the in situ maintenance of the implant over a sufficiently long period of time according to the clinical situation.

A two-step embedding process for better preservation of soft tissue surrounding coral implants

Infiltration of paraffin or embedding polymers proceeds more quickly in soft than in mineralized tissue specimens (bone or biomaterial). The proposed method takes advantage of this difference to protect soft tissue from the action of decalcifying agents. After embedding a bone-soft-tissue sample in a hydrophobic polymer, it is cleared of the resin on one of its sides to permit access of the decalcifying solution to the mineral component. A second infiltration with another polymerizable solution that cures in the empty pores created by the dissolution makes it possible to obtain a homogeneous hard block, make thin slices, and perform enzyme histochemistry and immunostaining on well-preserved soft tissue with most of its antigenic and enzymatic properties intact.

The resorption of bone-implanted corals varies with porosity but also with the host reaction

Three different exoskeletons of coral species Porites asteroides (P), Montastrea annularis (M), and Dichocoenia stokesi (D) were implanted for 2-20 weeks in rabbits. At 2, 4, 8, or 20 weeks, the exoskeletons presented variations in their resorptions depending on the species. To understand the variations in the decreasing speed of the implants despite their similar chemical composition, a study of the surface and architecture of the coral was carried out using scanning electronic microscopy, porosity was evaluated, and growth and differentiation of osteogenic cells cultured in vitro were observed for more than 1 month. At the cellular level, the surface of the implants was identical. Three-dimensional structures of the implants were variable, but the porosity values [P = 42.7%, M = 40.7%, and D = 17.4%] could not completely account for the differences in the resorbing process of the species. Standard histologic studies performed at 2, 4, 8, and 20 weeks after implantation produced the same pattern with P or M, showing aspects of rapid resorption; however, with D there were images resembling those of a foreign-body reaction. It seems that when resorption is not quick enough, a foreign body reaction develops which further slows down the process. This work focuses on the importance of porosity when using coral as bone substitute.