Clinical usefulness of microbiological diagnostic tools in the management of periodontal disease.

Periodontal diseases comprises a group of chronic inflammatory conditions affecting tooth supporting structures. It has been known for a long time that pathogenic oral bacteria colonizing the tooth surface are associated with the initiation of the disease process. However, to date, a dozen or so bacterial species have been implicated in the pathogenesis of periodontal disease and no one species by itself is synonymous with disease onset. This multibacterial etiology renders the diagnosis of active periodontal disease based on microbiological data difficult. Numerous studies have attempted to relate the usefulness of microbiological diagnostic aids such as microscopy, bacterial culture, immunological and enzymatic assays. Furthermore, recent technical advances have resulted in the use of nucleic acid probes and amplification techniques for the identification of genetic material belonging to potential periodontal pathogens. Despite the availability of a large number of microbiological testing protocols, identification of the microbial etiological agents remains hampered by the complexity of the microbial challenge during periodontal disease. This review discusses the clinical usefulness of these tests in detection and management of periodontal disease.

Intra-familial distribution of Fusobacterium nucleatum strains in healthy families with optimal plaque control.

Fusobacterium nucleatum, a Gram-negative anaerobic rod associated with periodontal disease, is also found in healthy individuals and is considered part of the indigenous oral microflora. Although intra-familial transmission of periodontal pathogens has been documented, there are no data relating transmission of F. nucleatum. This study investigated the distribution of F. nucleatum strains in 4 strictly healthy families. 32 F. nucleatum strains were isolated from 19 individuals (8 parents and 11 children aged 1-13 years). DNA was extracted and digested with the restriction endonucleases EcoRI, TaqI and HindIII. The digests were separated by electrophoresis through 0.8% agarose gels at 40 V overnight, in TBE buffer containing 1 microg/ml ethidium bromide, and photographed. The DNA was transferred to nylon filters by Southern blotting and hybridized with a digoxigenin labelled E. coli rRNA probe (Kit Dig DNA Labelling mixture - Boehringer). Probed DNA was visualized colorimetrically (CSPD Luminescent Detection Kit Boehringer) and photographed (Amersham). We found that 10/11 children shared identical ribotypes with at least one of their respective parents. Some of the children also harbored a unique additional ribotype. On the basis of indistinguishable restriction endonuclease and ribotype patterns these results support the hypothesis that intra-familial transmission of F. nucleatum is possible.

Clonal analysis by ribotyping of Fusobacterium nucleatum isolates obtained from healthy young adults with optimal plaque control.

Fusobacterium nucleatum is a Gram-negative anaerobic rod implicated in the pathogenesis of periodontal disease. However, this organism has also been frequently identified in high numbers in healthy adults. These observations suggest that the species may comprise different clonal types, some of which may participate in disease. The purpose of the present investigation was to use restriction endonuclease analysis (REA) and ribotyping to characterize F. nucleatum clonal types isolated from healthy young adults with optimal plaque control and investigate the stability of some of these clonal types. A group comprising 11 dental students and 11 dental outpatients with optimal plaque control was sampled. Clonal stability was investigated by sampling the dental student group at baseline and at 16 months. One hundred and thirty-two clinical isolates of F. nucleatum were successfully recovered from 15/22 individuals. For the positive subjects, 29 different clonal types were identified by REA and ribotyping, each subject and site being colonized by 1-4 clonal types. For the dental students, 9 and 15 different clonal types were identified at baseline and 16 months, respectively. None of the students harboured identical clonal types at both sampling times. Our results show that ribotyping is a useful technique for monitoring the distributions of F. nucleatum clonal types and indicate that healthy individuals with optimal plaque control can be colonized by more than one F. nucleatum clonal type and that these clonal types appear to be unstable.

Interactions between non-immune host cells and the immune system during periodontal disease: role of the gingival keratinocyte.

Periodontal disease and inflammatory dermatoses, such as psoriasis, are characterized by the accumulation of dense inflammatory infiltrates immediately beneath the epithelial cell layer of the gingiva and skin, respectively. Dermatologists are increasingly aware that the epidermal keratinocyte probably contributes to inflammatory disease progression by secreting a number of pro-inflammatory cytokines and expressing various adhesion molecules. In psoriatic lesions, it is now believed that epidermal keratinocytes may also act as antigen-presenting cells and participate directly in the superantigenic activation of T-cell clones, some of which may initiate, contribute to, or maintain the disease process. Although the role of the host response in periodontal disease has been extensively studied over the years, very little is known about the contribution of the gingival keratinocyte to the inflammatory response. The available published information is discussed in this review, and we suggest that, like its epidermal counterpart, the gingival keratinocyte may participate actively in the pathogenesis of periodontal disease.

Antimicrobial activity of amalgams, alloys and their elements and phases.

OBJECTIVES: This in vitro study aimed to evaluate the antibacterial effect of amalgams, alloys, elements and phases against two cariogenic bacteria, Actinomyces viscosus and Streptococcus mutans. METHODS: Test materials comprised: (i) commercial amalgams comprising Amalcap (Vivadent), Cavex Avalloy LC and DP (Cavex), Cupromuc (Merz), Fluoralloy and Synalloy (Dentoria); (ii) Ag-Cu alloy; (iii) gamma, gamma 1, gamma 2 and Cu6Sn5 phases; (iv) pure metal samples and chloride solutions of copper, mercury, tin and zinc; and (v) aqueous sodium fluoride. Bacterial suspensions of each of the two bacteria were grown in the presence of the test materials for 24 h. Antimicrobial effectiveness was assessed by measuring reduction in optical density at 640 nm using a visible spectrophotometer. RESULTS: Cupromuc/Fluoralloy, non gamma 2 amalgams and Amalcap displayed high, moderate and no antibacterial activity, respectively. Antibacterial effectiveness was not related to copper content. Whereas mercury, copper, Ag-Cu alloy, fluoride and zinc showed antibacterial activity (Hg > Cu > F > Zn), tin, gamma phases and Cu6Sn5 showed no such activity. SIGNIFICANCE: Although the fluoride and copper solutions were most effective at 50 micrograms ml-1 concentration, their antibacterial action was still significant, albeit reduced, at 10 micrograms ml-1 concentration. This was not the case for mercury chloride which was just as effective at both concentrations. Our results show that although mercury and copper contribute significantly to the antibacterial properties of amalgams, a high copper content does not necessarily relate to high antibacterial effectiveness. These elements could be useful in conferring antibacterial properties to amalgam although their effects on host cells must be investigated.

In vitro evaluation of the antibacterial effects of intracanal micro plasma system treatment.

Forty freshly extracted single-rooted teeth were prepared to a size 25 master apical file, autoclaved, and inoculated with a known quantity of Actinomyces naeslundii. The teeth were divided into four groups (n = 10), including an untreated control group. The three treatment groups were exposed to Micro Plasma System (MPS), 0.5% NaOCl and 0.5% NaOCl + MPS respectively. The content of each root canal was absorbed by sterile paper points, diluted in 2 ml Schaedler Broth Medium, and incubated on blood agar. The number of CFU was determined. Data analysis, using an analysis of variance and Scheffe's test at the 1% level (Statview II software), indicated a significant reduction in CFU count for the three treatment groups compared to the control group. For the three treatment groups, no significant intergroup differences were observed.