DNA probe detection of periodontal pathogens

The technology for hybridization of nucleic acids using isotopically labeled whole genomic or species-specific cloned deoxyribonucleic acid (DNA) probes for Actinobacillus actinomycetemcomitans, Bacteroides intermedius and Bacleroides gingivulis can be used to detect as few as 102 cells of these periodontal pathogens. The sensitivity and specificity of the test is not affected by the presence of 5x 10s unrelated bacteria in constructed mixed culture samples. Current feasibility tests with non-isotopic reagents also give reliable and rapid detection of these oral pathogens in pure or mixed cultures. DNA probes should prove useful in a rapid, specific, and sensitive assay for these periodontal pathogens.     

Early effects of periodontal therapy on the detection frequency of four putative periodontal pathogens in adults.

This study aimed to examine early posttreatment changes in the periodontal microflora. Paper point sampling and conventional bacterial cultivation were used to monitor the effects of surgical and non-surgical periodontal therapy on the detection frequency of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and Capnocytophaga species in deep periodontal pockets. Ten patients, 5 men and 5 women (mean age 44 years), with advanced periodontal disease were selected from the dental school patient population for the study. A total of 245 teeth in 10 defined areas of the dentition were treated by oral hygiene instruction followed by scaling and root planing alone (121 sites) or with surgical interventions (124 sites). Ninety sites, 47 surgical and 43 non-surgical, with initial pocket depth greater than or equal to 6 mm were sampled at baseline and 3 months after completion of therapy. Treatment by both procedures resulted in significant clinical improvements as assessed by all clinical parameters used. Baseline results may indicate that the level of P. gingivalis was reduced in the presence of P. intermedia, while A. actinomycetemcomitans seemed to be reduced in the presence of P. gingivalis and/or P. intermedia. Three months after therapy, the detection frequency of P. gingivalis was significantly reduced (P less than 0.05) in surgical and non-surgical sites while the reduction for P. intermedia was significant only for surgical sites (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

DNA probe detection of periodontal pathogens in HIV-associated periodontal lesions

Recent studies have shown that an atypical gingivitis and a rapidly progressive periodontal disease may be early-occurring opportunistic infections associated with human immunodeficiency virus (HIV) infection. This study examined the prevalence of selected periodontal pathogens associated with these HIV-related periodontal lesions. Subgingival plaque samples were obtained from both HIV-seronegative and HIV-seropositive homosexual men and from presumably uninfected heterosexual men. DNA probes were used to detect Actinobacillus actinomycetemcomitans, Bacteroides intermedius, Bacteroides gingivalis, Eikenella corrodens and Wolinella recta in the plaque. The healthy sites in both the seronegative and seropositive homosexual groups showed a greater prevalence of all test bacteria, except for E. corrodens, than did the heterosexual group. HIV-associated periodontitis sites showed a microbial profile qualitatively similar to that of conventional periodontitis, except that B. gingivalis was more prevalent in conventional periodontitis. In contrast, HIV-associated gingivitis sites exhibited a greater prevalence of all bacteria tested than conventional gingivitis sites. In fact, HIV gingivitis generally showed a bacterial profile similar to that of the HIV periodontitis lesions, except that W. recta was significantly more prevalent in HIV periodontitis. These data suggest that the HIV gingivitis lesion is a precursor to HIV periodontitis. Thus, early identification and prophylactic treatment of high-risk individuals may prevent the destruction of periodontal tissues.     

Survival analysis of periodontal sites before and after periodontal therapy

Periodontal diseases appear to progress with bursts of destructive activity at individual sites. One effect of treatment might be to diminish the frequency of such bursts. Survival analysis was employed to seek such effects on the periodontal sites of 16 individuals with prior evidence of destructive periodontal disease. The subjects were monitored at bi-monthly intervals and actively breaking down sites were detected using attachment level measurements and the tolerance method of analysis. When active sites were detected, control sites of equal pocket depth and attachment loss were selected and microbiological and immunological samples were taken. The subjects were treated by modified Widman flap surgery and systemically administered tetracycline. On completion of therapy, bi-monthly monitoring was reinstituted. Life tables were constructed for periodontal sites in each of the 16 subjects prior to and after therapy. A site losing more than 3 mm of attachment at any time interval was considered to have relapsed or "died". Survivor functions were calculated for each time period indicating the % of sites which survived at any time. The subjects were divided into 3 categories on the basis of post-therapy survivor functions. The annual hazard rate in 9 good treatment response subjects (group 1) was reduced from 0.10/year to 0.01/year. The hazard rate of 5 intermediate treatment response subjects (group 2A) was reduced from 0.16/year to 0.04/year and that of 2 poor treatment response subjects (group 2B) from 0.15/year to 0.07/year. Group 2A and 2B individuals were combined and differences were sought in clinical, microbiological and immunological parameters between the good and poor treatment response groups. 5 out of 7 of the poor responding individuals showed elevated humoral antibody responses to 3 or more gram-negative subgingival species tested. Many of the elevated responses in this group were to organisms which are widely distributed and return quickly after therapy such as Fusobacterium nucleatum, Eikenella corrodens, Bacteroides intermedius and Capnocytophaga sputigena. The predominant cultivable microbiota in subgingival samples taken prior to therapy from the good responding group had significantly greater proportions of Actinobacillus actinomycetemcomitans, C. ochracea and B. intermedius than the poor responding group. The latter group showed significantly elevated proportions of F. nucleatum, Peptostreptococcus micros and Streptococcus intermedius.     

牙周基础治疗对龈下牙周致病菌的影响

人类口腔是一个复杂的生态环境,许多研究证明龈下菌斑是引起和加重牙周炎的重要因素之一.目前已在口腔中发现700余种细菌,其中30余种与牙周病有关,因此学者们提出清除牙周致病菌是牙周病治疗的基础.龈下刮治和根面平整术作为一种已经被广泛认可的控制牙周致病菌的方法,在牙周病的临床治疗中被大量地应用.本文主要从以下几方面综述:①牙周致病菌的概念和特点;②龈下刮治和根面平整术在龈下牙周致病菌的消除和控制中的作用;③龈下刮治和根面平整术在龈下牙周致病菌的消除和控制中的不足.     

Sampling of periodontal pathogens by paper points: evaluation of basic parameters

Paper points are widely established for the collection of subgingival plaque or other oral samples to analyze the microbiota, especially the presence of periodontal pathogenic bacteria such as Actinobacillus actinomycetemcomitans or Porphyromonas gingivalis. In contrast to the high frequency of usage of paper points in oral sampling, very few data are available about the parameters influencing the sampling process. Therefore, in four different in vitro experiments (6-9 repeats), we inoculated paper points with standardized suspensions (2 x 10(9) colony-forming units/ml) of A. actinomycetemcomitans and P. gingivalis to test the influence of the origin (kind) of paper point ("manufacturer"), size (according to the International Organization for Standardization ISO 25-80), sampling time (5 to 60 s), and elution time (5 to 60 s). Sampled bacteria were detected and (semi-) quantified using 16S rRNA/DNA-directed oligonucleotide probes. The bacterial load was categorized and calculations performed with index values ranging between 0 (below the detection limit of 10(2) to 10(3) colony-forming units) and 9 (> 10(6) colony-forming units). We found statistically significant differences in the efficiency of bacterial sampling between the 5 paper point manufacturers tested, expressed in a mean bacterial index between 4.4 and 7.8. ISO 45 Paper points were statistically proven to work most efficiently. According to our results, a sampling time of 60 s seems to be optimum. However, shorter times between 5 and 30 s did not significantly reduce the sampling efficiency. We found an interval of 20 s best to elute bacteria from the paper points by vortexing. The evaluation of basic parameters for subgingival plaque sampling by paper points might help to optimize microbiologically based diagnostics in periodontal diseases.     

Improved periodontal conditions following therapy

The aim of the present clinical trial was to evaluate the effect of different modes of periodontal therapy on patients with moderately advanced periodontal disease and to express the findings in terms of probing pocket depth and attachment level alterations at periodontal sites with different initial probing depths. The material consisted of 16 patients, 35-65 years of age. Following a Baseline examination including assessments of oral hygiene status, gingival conditions, probing pocket depths and probing attachment levels, the patients were subjected to periodontal treatment. A "split-mouth" design approach of therapy was used and the jaw quadrants were randomly selected for the following different treatment procedures: (1) scaling and root planning, (2) scaling and root planing in conjunction with a gingivectomy procedure, (3) scaling and root planing in conjunction with an apically repositioned flap procedure without bone recontouring, (4) scaling and root planing in conjunction with an apically repositioned flap procedure including bone recontouring, (5) scaling and root planing in conjunction with a modified Widman flap procedure without bone recontouring and (6) scaling and root planing in conjunction with a modified Widman flap procedure including bone recontouring. The patients were following active treatment enrolled in a supervised maintenance care program including "professional tooth cleaning" once every 2 weeks during a 6-month period of healing, after which a final examination was performed. The investigation demonstrated that active therapy including meticulous subgingival debridement resulted in a low frequency of gingival sites which bled on probing, a high frequency of sites with shallow pockets (less than 4 mm) and the disappearance of pockets with a probing depth of greater than 6 mm. Between the Baseline examination and the 6-month re-examination, the probing attachment level for initially shallow pockets remained basically unaltered, but with a tendency of a minor apical shift. This occurred in all 6 treatment groups. For sites with initial probing depths of 4-6 mm and greater than 6 mm, there was in all groups some gain of probing attachment. This gain was most pronounced in the initially deeper (greater than 6 mm) pockets. With the use of regression analysis, the "critical probing depth" (CPD) value (i.e. the initial probing depth value below which loss of attachment occurred as a result of treatment and above which gain of probing attachment level resulted) was calculated for each of the 6 methods of treatment used. A comparison of the CPD-values between the 6 treatment groups did not reveal any major differences.     

Salivary IgG and IgA before and after periodontal therapy

In a study of whole saliva of 12 patients with periodontal disease, IgG concentration was found to be higher and IgA concentration lower, before oral hygiene therapy and periodontal surgery than afterwards. The concentration of these immunoglobulins after periodontal therapy was comparable with those found in clinically normal individuals.     

Wound healing following surgical and regenerative periodontal therapy

Clinical studies have evaluated the effect of conventional periodontal surgical therapy. In general, although some clinical gain in tissue support may be attained, these therapies do not support regeneration of the periodontal attachment. Even though the biological possibility of periodontal regeneration has been demonstrated, the clinical application of this intrinsic potential appears difficult to harness; thus also conceptually most intriguing candidate protocols face clinical challenges. In this review, we explore the bioclinical principles, condiciones sine quibus non, that unleash the innate potential of the periodontium to achieve clinically meaningful periodontal regeneration (i.e. space‐provision, wound stability and conditions for primary intention healing). Moreover, limiting factors and detrimental practices that may compromise clinical and biological outcomes are reviewed, as is tissue management in clinical settings.     

Influence of sampling strategy on microbiologic results before and after periodontal treatment

BACKGROUND: The aim of this study was to test whether different sampling strategies would influence the microbiologic outcomes by assessing the bacterial load and composition of the subgingival microbiota by means of anaerobic culturing before and after periodontal treatment. METHODS: The first study (1 versus 4 [1vs4]) included 33 patients with generalized chronic periodontitis. Two sampling strategies were compared, sampling one site from the deepest pocket in the mouth (M1) versus a pooled sample of four sites from the deepest pockets in each quadrant (M4). The second study (2 versus 4 [2vs4]) included 20 patients with generalized chronic periodontitis. The strategy M4 was compared to a pooled sample of two non-adjacent sites in the same quadrant (M2). All samples were processed identically by means of anaerobic culturing. In both studies, a pretreatment sampling was taken. However, in the second study (2vs4), subgingival samples were also taken at 1, 3, and 6 months after periodontal therapy. Quantitative data were compared between strategies by means of t test and signed-rank test; qualitative data were compared by means of 2 x 2 contingency tables. RESULTS: Pretreatment samples showed that total anaerobic counts were significantly higher for M4 compared to M1 (P <0.001) and M2 (P = 0.025). However, there were no significant differences in regard to percentage of microbiota and counts for each pathogen. Most of the qualitative differences between strategies were caused by false negatives in M1 and M2. Post-treatment samples showed a reduction in total counts and a limited impact in the frequency of detection of periodontal pathogens. M2 detected a significant decrease in the frequency of detection of Porphyromonas gingivalis, which was not confirmed by the M4 strategy. CONCLUSION: The criteria of selection and the number of sites selected when sampling the subgingival biofilm in patients with generalized chronic periodontitis may influence the detection and quantitation of periodontal pathogens when evaluated by culture especially after treatment.     

Immunological assays for putative periodontal pathogens

Immunological tests including immunofluorescence microscopy, latex agglutination, flow cytometry, and enzyme-linked immunosorbent assays are being developed for the detection of carcinogenic microorganisms and periodontal pathogens. In the present study, indirect immunofluorescence microscopy was used to examine two hundred eighty-three subjects for Actinobacillus ("Haemophilus") actinomycetemcomitans and Bacteroides gingivalis in subgingival dental plaque samples pooled from the mesial surface of the four first molar teeth. Alveolar bone height on panoramic radiographs was measured at each sample site using a Schei ruler and correlated with the results of immunofluorescence microscopy. Over ninety percent of the subjects did not demonstrate either putative periodonlal pathogen or harbored only trace amounts. Only 5% of the subjects demonstrated 2% or greater A. actinomycclemcomitans and no subject harbored more than 5% consistent with the finding that there were no localized juvenile periodontitis patients in this subject group. Nine percent of the subjects revealed 2% or more, and 5% demonstrated 5% or more of the total cell count as B. gingivalis. K. gingivalis levels , however, did exhibit a significant positive correlation with loss of alveolar bone height. The use of immunofluorescence microscopy for B. gingivalis exhibited 19% sensitivity, 96% specificity, 69% positive predictive value, and 69% negative predictive value when correlated with alveolar bone height measurements. The present data indicate that indirect immunofluorescence microscopy is a useful, rapid method for the detection of A. actinomycetemcomitans and B. gingivalis in subgingival dental plaque which can be used in the clinical diagnosis, treatment, and monitoring of periodontal disease. The sensitivity of microbiological assays as indicators of periodontal disease can likely be increased by utilization of additional Immunological tests for other putative periodontal pathogens.     

Bone loss following periodontal therapy in subjects without frequent periodontal maintenance

The longitudinal effects of periodontal therapy in patients without a frequent periodontal maintenance program have been minimally documented. In this study we used Duckworth's modification of the Schei Ruler Technique to assess the difference in bone level around individual teeth treated for periodontal disease in subjects receiving infrequent posttherapy maintenance (less than or equal to 1 time/year). Crestal bone height differences were evaluated using the initial presenting series of long cone parallel radiographs of 23 subjects with their subsequent posttherapy analogous radiographic series taken 5.4 +/- 2.9 years later. Bone loss was defined as a reduction in the alveolar crest of greater than 50% of the radiographic crown height which corresponds to approximately 4 mm in posterior and 5 mm in anterior teeth. The loss for each tooth was expressed as a per cent of the measured height of the crown after conversion from millimeters using the mean crown-root ratio for each tooth. We found increased alveolar bone loss and tooth loss in subjects examined posttherapy when compared with conditions present when each subject initially presented for periodontal treatment. Our data suggest that molar teeth are more at risk than incisors and cuspids and that a lack of periodontal maintenance care and inadequate plaque control contribute to progressive bone loss following treatment.     

Significance of probing force for evaluation of healing following periodontal therapy

The present report compares pre- and postoperative probing pocket depths and probing attachment levels in deep pockets treated non-surgically as well as surgically using probing forces at 0.25 N, 0.50 N and 0.75 N. The results demonstrated that the recorded mean pre- and postoperative probing depths were deeper with increasing probing force. In deep preoperative pockets, the difference amounted to as much as 2.0 mm comparing measurements at 0.25 N and 0.75 N. The use of 0.25 N for evaluation of therapy showed less mean pocket reduction and probing attachment gain than the use of 0.50 N or 0.75 N. Selection of a higher probing force before therapy (i.e. 0.75 N) and a lower force after therapy (i.e. 0.25 N) resulted in increased values for pocket reduction and probing attachment gain compared to use of the same probing force for both pre- and postoperative recordings. The findings emphasize the significance of using a known and standardized probing force for evaluation of results following periodontal therapy.