Though biofilms were first described by Antonie van Leeuwenhoek, the theory describing the biofilm process was not developed until 1978. We now understand that biofilms are universal, occurring in aquatic and industrial water systems as well as a large number of environments and medical devices relevant for public health. Using tools such as the scanning electron microscope and, more recently, the confocal laser scanning microscope, biofilm researchers now understand that biofilms are not unstructured, homogeneous deposits of cells and accumulated slime, but complex communities of surface-associated cells enclosed in a polymer matrix containing open water channels. Further studies have shown that the biofilm phenotype can be described in terms of the genes expressed by biofilm-associated cells. Microorganisms growing in a biofilm are highly resistant to antimicrobial agents by one or more mechanisms. Biofilm-associated microorganisms have been shown to be associated with several human diseases, such as native valve endocarditis and cystic fibrosis, and to colonize a wide variety of medical devices. Though epidemiologic evidence points to biofilms as a source of several infectious diseases, the exact mechanisms by which biofilm-associated microorganisms elicit disease are poorly understood. Detachment of cells or cell aggregates, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are all biofilm processes which could initiate the disease process. Effective strategies to prevent or control biofilms on medical devices must take into consideration the unique and tenacious nature of biofilms. Current intervention strategies are designed to prevent initial device colonization, minimize microbial cell attachment to the device, penetrate the biofilm matrix and kill the associated cells, or remove the device from the patient. In the future, treatments may be based on inhibition of genes involved in cell attachment and biofilm formation.

Biofilms: Survival Mechanisms of Clinically Relevant Microorganisms

A review of the biological response to ionic dissolution products from bioactive glasses and glass-ceramics

Microbial etiological agents of destructive periodontal diseases

Dental diseases are among the most prevalent and costly diseases affecting industrialized societies, and yet are highly preventable. The microflora of dental plaque biofilms from diseased sites is distinct from that found in health, although the putative pathogens can often be detected in low numbers at normal sites. In dental caries, there is a shift towards community dominance by acidogenic and acid-tolerant Gram-positive bacteria (e.g. mutans streptococci and lactobacilli) at the expense of the acid-sensitive species associated with sound enamel. In contrast, the numbers and proportions of obligately anaerobic bacteria, including Gram-negative proteolytic species, increase in periodontal diseases. Modelling studies using defined consortia of oral bacteria grown in planktonic and biofilm systems have been undertaken to identify environmental factors responsible for driving these deleterious shifts in the plaque microflora. Repeated conditions of low pH (rather than sugar availability per se) selected for mutans streptococci and lactobacilli, while the introduction of novel host proteins and glycoproteins (as occurs during the inflammatory response to plaque), and the concomitant rise in local pH, enriched for Gram-negative anaerobic and asaccharolytic species. These studies emphasized (a) significant properties of dental plaque as both a biofilm and a microbial community, and (b) the dynamic relationship existing between the environment and the composition of the oral microflora. This research resulted in a novel hypothesis (the ‘ecological plaque hypothesis’) to better describe the relationship between plaque bacteria and the host in health and disease. Implicit in this hypothesis is the concept that disease can be prevented not only by directly inhibiting the putative pathogens, but also by interfering with the environmental factors driving the selection and enrichment of these bacteria. Thus, a more holistic approach can be taken in disease control and management strategies.

Are dental diseases examples of ecological catastrophes

A classification scheme for periodontal and peri-implant diseases and conditions is necessary for clinicians to properly diagnose and treat patients as well as for scientists to investigate etiology, pathogenesis, natural history, and treatment of the diseases and conditions. This paper summarizes the proceedings of the World Workshop on the Classification of Periodontal and Peri-implant Diseases and Conditions. The workshop was co-sponsored by the American Academy of Periodontology (AAP) and the European Federation of Periodontology (EFP) and included expert participants from all over the world. Planning for the conference, which was held in Chicago on November 9 to 11, 2017, began in early 2015. An organizing committee from the AAP and EFP commissioned 19 review papers and four consensus reports covering relevant areas in periodontology and implant dentistry. The authors were charged with updating the 1999 classification of periodontal diseases and conditions and developing a similar scheme for peri-implant diseases and conditions. Reviewers and workgroups were also asked to establish pertinent case definitions and to provide diagnostic criteria to aid clinicians in the use of the new classification. All findings and recommendations of the workshop were agreed to by consensus. This introductory paper presents an overview for the new classification of periodontal and peri-implant diseases and conditions, along with a condensed scheme for each of four workgroup sections, but readers are directed to the pertinent consensus reports and review papers for a thorough discussion of the rationale, criteria, and interpretation of the proposed classification. Changes to the 1999 classification are highlighted and discussed. Although the intent of the workshop was to base classification on the strongest available scientific evidence, lower level evidence and expert opinion were inevitably used whenever sufficient research data were unavailable. The scope of this workshop was to align and update the classification scheme to the current understanding of periodontal and peri-implant diseases and conditions. This introductory overview presents the schematic tables for the new classification of periodontal and peri-implant diseases and conditions and briefly highlights changes made to the 1999 classification. It cannot present the wealth of information included in the reviews, case definition papers, and consensus reports that has guided the development of the new classification, and reference to the consensus and case definition papers is necessary to provide a thorough understanding of its use for either case management or scientific investigation. Therefore, it is strongly recommended that the reader use this overview as an introduction to these subjects. Accessing this publication online will allow the reader to use the links in this overview and the tables to view the source papers (Table 1).

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A new classification scheme for periodontal and peri-implant diseases and conditions - Introduction and key changes from the 1999 classification.

Antibacterial activity of particulate bioglass against supra- and subgingival bacteria.

The reported prevalence of cervical dentine sensitivity (CDS) ranges from 8 to 35%. Detailed epidemiology of the condition, particularly with regard to possible causal factors, is lacking. In particular, no published data appear to exist on its prevalence in periodontal patients. The aim of the present study was therefore to determine the prevalence, distribution and severity of CDS in a population of patients referred to a Periodontology Department of a specialist postgraduate hospital. 507 patients (181 M; 326F, mean age 44.2 (SD 10.31) years) attending a periodontal clinic were assessed for CDS by a questionnaire. The results demonstrated a prevalence of CDS of 84% with no significant gender difference. 71.1% of patients perceived cold as the most common cause of discomfort. A higher prevalence of self-reported discomfort was observed between 40 and 49 years. Of the patients with a reported history of periodontal surgery (34.7%), those treated within 6 months prior to assessment appeared to be more at risk to CDS. Of the patients who received hygienist treatment (88.2%), only 10.5% reported discomfort persisting > or = 3 days after treatment. Generally, patients who complained of varying degrees of discomfort over time (84.5%) did not perceive the condition as severe and consequently did not seek treatment. The prevalence of CDS in these referred patients was very high, suggesting that periodontal diseases and/or treatment effects play a role in its aetiology.

Prevalence of cervical dentine sensitivity in a population of patients referred to a specialist Periodontology Department

Recent studies have attempted to determine the prevalence of dentine hypersensitivity (DH) in both hospital and general practice. Results indicate that DH prevalence is higher in patients referred for specialist treatment than in general practice. The aim of this study was to determine perception and prevalence of DH in general practice. Completed questionnaires from 277 patients (115 males, 162 females, mean age 41.7 years [SD 14.36]) were collected. Self-reported DH prevalence (52%) was observed between the third and fourth decades, peaking in the third and in good agreement with that previously published (45.2%), and significantly more females complained of DH than males (SND=2.24, 95% CI 0.01734-0.2661). Cold was perceived as the most common cause of DH, in agreement with other studies. Only 12.6% of patients reported periodontal surgery compared to 15.5% previously. Of those who received hygiene therapy (67.9%) only 15.5% reported DH following treatment which mainly did not last >/=5 days. Most patients with DH did not perceive the condition as severe and did not seek treatment (75.1%). Only 23.3% used a desensitizing dentifrice. The results indicated that self-reporting of DH is lower than reported in a dental hospital population and was not perceived as a major dental problem by most patients in a general dental practice population.

Perceptions of dentine hypersensitivity in a general practice population.

The purpose of this study was to determine the susceptibility to chlorhexidine of a range of bacteria which may be isolated from subgingival plaque. In addition, the effect of chlorhexidine on the survival of bacteria in subgingival plaque samples from patients with chronic inflammatory periodontal disease was investigated. The minimum inhibitory concentration (MIC) of chlorhexidine for 52 strains of bacteria ranged from 8 to 500 μ/gml. The modal value of the MIC was found to be 62 μ/gm/l, 64% of the strains tested being inhibited at this concentration. A concentration of 250 μ/g/ml of chlorhexidine inhibited the growth of all bacteria in the 25 subgingival plaque samples investigated. The MTC of chlorhexidine for the samples ranged from 31 to 250 μ//g/ml, the modal value being 125 μ//g/ml.

The in vitro effects of chlorhexidine on subgingival plaque bacteria

The prevalence of tooth sensitivity [Cervical Dentine Sensitivity (CDS)] in adult populations indicates that 8-35% of subjects reported CDS depending on the population studied and the methodology used. Few studies, however, have reported on the prevalence of CDS in periodontal patients. The aim of the study was to determine the prevalence, severity and distribution of CDS in patients referred for specialist periodontal diagnosis. Fifty-one patients [27 male, 24 female; mean age 48.5 years (standard deviation 11.63)] who gave their informed written consent were clinically evaluated for CDS using recognized methods of assessment, namely Yeaple probe, cold air blast and subjective evaluation. Other clinical variables (e.g. plaque and recession scores) were also recorded at this visit. Regression analysis and correlation coefficients were used to determine the relationship between the clinical variables. The results demonstrated a prevalence of CDS ranging between 72.5 and 98% of patients, with no significant gender difference. Results for the distribution of tooth types showed that molar teeth were mainly affected, followed by left canines and premolars. No correlation was noted between plaque, recession, response to tactile or thermal stimulation. Pain response from tactile and thermal stimulation showed no significant difference between tooth surfaces. Cold stimulation was perceived to be the dominant pain-producing stimulus as had been previously reported. The results of this investigation support those from another study, which found the prevalence of CDS to be higher in periodontal patients than has been reported elsewhere. This finding would suggest that previous periodontal treatment and/or periodontal disease may play a role in the aetiology of CDS.

Hn Newman

Papers

Antibacterial activity of particulate bioglass against supra- and subgingival bacteria.

Prevalence of cervical dentine sensitivity in a population of patients referred to a specialist Periodontology Department

Perceptions of dentine hypersensitivity in a general practice population.

The in vitro effects of chlorhexidine on subgingival plaque bacteria

Clinical evaluation of cervical dentine sensitivity in a population of patients referred to a specialist periodontology department: a pilot study.