Summary: Microorganisms coexist in a complex milieu of bacteria, fungi, archaea, and viruses on or within the human body, often as multifaceted polymicrobial biofilm communities at mucosal sites and on abiotic surfaces. Only recently have we begun to appreciate the complicated biofilm phenotype during infection; moreover, even less is known about the interactions that occur between microorganisms during polymicrobial growth and their implications in human disease. Therefore, this review focuses on polymicrobial biofilm-mediated infections and examines the contribution of bacterial-bacterial, bacterial-fungal, and bacterial-viral interactions during human infection and potential strategies for protection against such diseases.

Polymicrobial Interactions: Impact on Pathogenesis and Human Disease

Oral infections caused by yeast of the genus Candida and particularly Candida albicans (oral candidoses) have been recognised throughout recorded history However, since the 1980s a clear surge of interest and associated research into these infections have occurred This has largely been due to an increased incidence of oral candidosis over this period, primarily because of the escalation in HIV-infection and the AIDS epidemic In addition, changes in medical practice leading to a greater use of invasive clinical procedures and a more widespread use of immunosuppressive therapies have also contributed to the problem Whilst oral candidosis has previously been considered to be a disease mainly of the elderly and very young, its occurrence throughout the general population is now recognised Candida are true 'opportunistic pathogens' and only instigate oral infection when there is an underlying predisposing condition in the host Treatment of these infections has continued (and in some regards continues) to be problematic because of the potential toxicity of traditional antifungal agents against host cells The problem has been compounded by the emergence of Candida species other than C albicans that have inherent resistance against traditional antifungals The aim of this review is to give the reader a contemporary overview of oral candidosis, the organisms involved, and the management strategies that are currently employed or could be utilised in the future

https://www.tandfonline.com/doi/pdf/10.3402/jom.v3i0.5771

Pathogenesis and treatment of oral candidosis

Candida albicans is a dimorphic yeast strongly gram positive able to live as normal commensal organism in the oral cavity of healthy people. It is the yeast more frequently isolated in the oral cavity. Under local and systemic factors related to the host conditions, it becomes virulent and responsible of oral diseases known as oral candidiasis. It has been shown that the presence of denture is a predisposing factor to the onset of pathologies related to C. albicans. Clinical studies have shown that C. albicans is not only able to adhere to the mucous surfaces, but also to stick to the acrylic resins of the dental prostheses. Both the plaque accumulated on the denture and the poor oral hygiene contribute to the virulence of Candida, offering the clinical picture of Candida-associated denture stomatitis. The therapeutic strategies currently adopted in the clinical practice to overcome these fungal infections provide for the use of topical and/or systemic antifungal and topical antiseptics and disinfectants, the irradiation with microwaves and the accurate mechanical removal of the bacterial plaque from the denture surfaces and from the underlying mucosa. A correct oral hygiene is important for the control of the bacterial biofilm present on the denture and on the oral mucosa and it is the fundamental base for the prophylaxis and the therapy of the Candidaassociated denture stomatitis.

/pdf/candida-associated-denture-stomatitis-5bh80nqa58.pdf

Candida-associated denture stomatitis.

Summary Saliva has many essential functions. As the first digestive fluid in the alimentary canal, saliva is secreted in response to food, assisting intake and initiating the digestion of starch and lipids. During this process, saliva acts as a solvent of taste substances and affects taste sensitivity. Clinically, a more important role is in the maintenance of oral health, including the protection of teeth and mucosa from infections, maintenance of the milieu of taste receptors, and communication ability through speech. Variations in salivary flow can be affected, reversibly or irreversibly, by numerous physiological and pathological factors. Decreased salivary flow results in clinically significant oral discomfort that may manifest as increased caries, susceptibility to oral candidiasis, altered taste sensation or as a host of other problems. Hyposalivation is a condition that is frequently encountered in dental practice. The most common cause is the use of certain systemic medications, which put the elderly at greater risk because they are usually more medicated. Other causes include high doses of radiation and certain diseases such as Sjogren’s syndrome. This article reviews the mechanism of salivary secretion, effect of saliva on taste, importance of saliva in oral health, and hyposalivation in relation to ageing, medicine and/or disease and management of hyposalivation.

Salivary secretion, taste and hyposalivation

The oral microbiota represents an important part of the human microbiota, and includes several hundred to several thousand diverse species. It is a normal part of the oral cavity and has an important function to protect against colonization of extrinsic bacteria which could affect systemic health. On the other hand, the most common oral diseases caries, gingivitis and periodontitis are based on microorganisms. While (medical) research focused on the planktonic phase of bacteria over the last 100 years, it is nowadays generally known, that oral microorganisms are organised as biofilms. On any non-shedding surfaces of the oral cavity dental plaque starts to form, which meets all criteria for a microbial biofilm and is subject to the so-called succession. When the sensitive ecosystem turns out of balance – either by overload or weak immune system – it becomes a challenge for local or systemic health. Therefore, the most common strategy and the golden standard for the prevention of caries, gingivitis and periodontitis is the mechanical removal of this biofilms from teeth, restorations or dental prosthesis by regular toothbrushing.

The Oral Microbiota.

In oral squamous cell carcinomas of the head and neck, Laminin-5 gamma2 has been associated with tissue invasion, lymph node metastasis and histopathological grading. In the present study, we compared the expression of the subunit gamma2 of Laminin-5 under normal, dysplastic and invading epithelia in 65 biopsies previously diagnosed for oral squamous cell carcinoma. The number of gamma2-positive cells were analyzed in relation to patients' survival, tumor grading, size of the lesion, TNM stage, histopathological pattern of invasion and inflammatory reaction. Biopsies of oral squamous cell carcinomas were deparaffinised, processed for antigen unmasking procedures and stained with antibody anti-Laminin-5 gamma2. By light microscopy, 4 optical fields of x200 were selected in three different areas including normal, dysplastic and invading epithelia. Positive cells were counted and divided into three categories, which included 50 stained cells. Patient survival was analyzed by Kaplan-Mayer curves. gamma2-positive cells were found in the basal layer of dysplastic epithelium, within inflammatory infiltrate, at the margins of differentiated invading islands and at the forefront of undifferentiated invading nests. Observations showed that an increased number of gamma2-positive cells correlated significantly with a shorter life expectancy under invading epithelia (log-rank test p<0.05), not when a count was performed under normal or dysplastic epithelia of the same patient. The number of gamma2-positive cells also correlated with the histopathological pattern of invasion. Our results show that gamma2 may be a reliable prognostic tool for oral squamous cell carcinomas.

https://www.spandidos-publications.com/10.3892/or.18.4.793/download

Prognostic value of differential expression of Laminin-5 γ2 in oral squamous cell carcinomas: Correlation with survival

Purpose: Candida albicans is a component of the normal oral microflora, but local and systemic factors can transform this commensal C albicans to a pathogen. The most frequent cause of Candida opportunistic infections (candidiasis) is dentures, especially if poorly fitting or poorly cleaned. Management of oral candidiasis depends on an accurate diagnosis, identification and elimination of predisposing factors, and, often, use of antifungal agents. The aim of this study was to examine fingernail varnish, currently used for onychomycosis therapy, to reduce the fungal colinization in prosthetic biofilms. Materials and Methods: A varnish containing 5%, amoroliine was applied once or twice a week for 6 months in six patients affected by mystatin-resistant denture-related stomatitis. In all six patients, the prostheses had previously been removed at night, and daily antimycotic topical therapy with mystatin had failed to resolve the stomatitis; after 30 days, these patients all showed persistence of candidal stomatitis. Results: After 1 month, five of the six patients were negative for Candida; this situation was unchanged in the following monthly controls. Only in the patient with suspected Sjogren syndrome was oral Candida found 13 days after the last varnish application. None of the patients had any complaints about the medication. Conclusion: This varnish containing 5% amorolfine. applied once of twice a week for 6 months, was able to suppress the nystatin-resistant denture-related stomatitis.

Candida-related denture stomatitis: a pilot study of the efficacy of an amorolfine antifungal varnish.

PURPOSE This study aims to evaluate differences in implant stability between post-extractive implants vs immediately placed post-extractive implants by resonance frequency analysis (RFA). MATERIALS AND METHODS Patients were grouped into two different categories. In Group A 10 patients had an immediate post-extractive implant, then a provisional, acrylic resin crown was placed (immediate loading). In Group B (control group) 10 patients only had an immediate post-extractive implant. Both upper and lower premolars were chosen as post-extractive sites. Implant Stability Quotient (ISQ) was measured thanks to RFA measurements (Osstell®). Five intervals were considered: immediately after surgery (T0) and every four weeks, until five months after implant placement (T1, T2, T3, T4,T5). A statistical analysis by means of Student's T-test (significance set at p<0.05) for independent sample was carried out in order to compare Groups A and B. RESULTS The ISQ value between the two groups showed a statistically significant difference (p<0.02) at T1. No statistically significant difference in ISQ was assessed at T0, T2, T3, T4 and T5. CONCLUSIONS After clinical assessment it is possible to confirm that provisional and immediate prosthetic surgery in post-extraction sites with cone-shaped implants, platform-switching abutment and bioactive surface can facilitate osseointegration, reducing healing time.

Immediate vs non-immediate loading post-extractive implants: a comparative study of implant stability quotient (ISQ).

Implant rehabilitation in oral lichen planus (OLP) is a major challenge for clinicians and patients. There is limited scientific evidence, primarily case reports and small case series. We conducted a literature review of data on the effectiveness and safety of implant rehabilitation in OLP patients. We searched MEDLINE, Embase and Cochrane databases for articles on implant placement in OLP patients (searches from 1980 to 2011). Eight studies (41 OLP patients rehabilitated with 135 implants) met the inclusion criteria. Survival rate of implants was 94.8% over a mean follow-up of 56.5 months. There is very limited evidence on the safety and benefits of implant placement in OLP patients. Implant loss appears not to be directly related to OLP, but linked to factors such as parafunctions, poor bone quality and marginal mandibular resection. The benefits and harms of using implants in people with OLP require thorough evaluation in properly designed randomised, controlled studies. OLP is not an absolute contraindication for implant insertion and there is no increased risk of failure. Implants should be positioned only if mucosal signs and symptoms are in the remission phase. A careful oral hygiene and frequent follow-up are the main recommendations in OLP patients rehabilitated with implants.

Lucio Milillo

Papers

Candida-associated denture stomatitis.

Prognostic value of differential expression of Laminin-5 γ2 in oral squamous cell carcinomas: Correlation with survival

Candida-related denture stomatitis: a pilot study of the efficacy of an amorolfine antifungal varnish.

Immediate vs non-immediate loading post-extractive implants: a comparative study of implant stability quotient (ISQ).

Implant rehabilitation in patients with oral lichen planus: an overview.