Biomedical subjects
S S Socransky
Publications and source records attributed to S S Socransky.
Comparison of statistical methods of analysis of data from clinical periodontal trials.
Data from clinical trials have commonly been analyzed by seeking differences between means of clinical measurements in groups treated in different ways. Such differences may be difficult to interpret clinically and fail to impart meaningful information to the research worker or clinician. Attachment level measurements taken from a group of well-maintained patients, initially treated by either scaling or Widman flap surgery, were artificially manipulated to impose known changes on the scaled group. Data from individual sites were analyzed by the t-test and Mann-Whitney test; and frequency distributions by the Kolmogorov-Smirnov 2-sample test and ridit analysis. Extreme changes were sought by the Moses test for extreme reactions and by creating contingency tables in which changes below arbitrary thresholds of change were eliminated. Examination of the results indicated that the mean was sensitive to small changes in large numbers of sites but insensitive to major changes in a smaller number of sites. Since the latter changes may be of significance to the research worker and clinician, it is recommended that the mean (or median values) be supplemented with the presentation of the frequency distribution of changes and an analysis seeking large changes in few sites.
Clinical parameters as predictors of destructive periodontal disease activity.
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Comparison of different data analyses for detecting changes in attachment level.
The purpose of the present investigation was to evaluate methods to detect periods of destructive periodontal disease activity in individual sites using pairs of repeated attachment level measurements. Attachment level measurements were made at 6 sites on every tooth in 22 individuals with radiographic evidence of periodontal destruction, and were repeated within 7 days. A total of 3414 sites were monitored at 2-month intervals for approximately 1 year. 3 analytical procedures were used to test for significant changes in attachment level. For regression analysis, a linear least squares fit function of time in days vs attachment level was computed for each site and the slope tested for difference from 0. Running medians of 3 were used to smooth attachment level measurements and changes greater than 2 mm in the smoothed curves were considered significant. By the tolerance method, differences between pairs of attachment level measurements were used to compare the mean change and the site specific variability of that change. The proportion of specific agreement (Ps) for breaking down sites was highest between the tolerance and running median methods (Ps = 0.63). Overall agreement (kappa), which included sites which showed "loss", "gain", and no change was 0.56. By regression analysis (P less than 0.01), 175 sites were identified as having significant attachment loss and 79 sites were identified as improving. By running medians these figures were 90 and 50, and by tolerance 94 and 40, respectively. Each of the 3 methods had certain advantages. Regression analysis was particularly sensitive to gradual changes in slope whereas the running median method detected abrupt changes in attachment level. The tolerance method was well suited to detecting changes over a short period of time. The tolerance and running median methods detected more breaking down sites on the molars and lower incisors and on interproximal surfaces; whereas regression analysis did not show these differences.
Antibiotic susceptibility testing of subgingival plaque samples.
The in vitro inhibitory effect of several antimicrobial agents was determined against dispensed dental plaque samples taken from periodontally diseased sites as an aid in the selection of antibiotics for adjunctive use in periodontal therapy. 2 groups of patients were sampled. 1 group of 10 patients with severely advanced disease had received periodontal treatment which included the frequent adjunctive use of an antibiotic. The second group consisted of 15 individuals with less severe periodontal disease; only 4 individuals had been previously treated with antibiotics for their periodontal disease. Bacterial samples of subgingival plaque were taken from each patient and tested against a battery of antibiotics to determine which agent was the most effective in suppressing bacterial growth. Each antibiotic was incorporated into Trypticase-soy blood agar at a concentration equivalent to that achieved in either gingival fluid or blood following recommended oral dosages. The inhibitory effect was determined by comparing the number of bacterial recovered on the antibiotic-containing medium to the total number of bacteria recovered on the basal medium. Penicillins, with the exception of cloxacillin, were the most effective in inhibiting bacterial growth. Benzylpenicillin consistently inhibited the growth of 90% of the isolates recovered on media free of antibiotics while ampicillin and amoxicillin frequently inhibited 99% or more of the bacteria recovered. Tetracycline was generally inhibitory for at least 90% of the isolates if the patients had not been previously treated with this agent. However, resistance to this drug was common in samples taken from patients previously treated with tetracycline. Doxycycline, a tetracycline derivative, did not inhibit significantly more isolates than tetracycline. Clindamycin was inhibitory for 90% or more of the organisms in most of the samples; and, was usually effective in inhibiting isolates in samples which exhibited large numbers of isolates resistant to tetracycline. Erythromycin was relatively ineffective against the isolates recovered from samples from the severely diseased group but was inhibitory to isolates in some samples taken from the more moderately diseased group. Metronidazole, at the concentration tested, was largely ineffective against the isolates in bacterial samples from both groups. No single antimicrobial agent was found to be inhibitory for greater than 90% of the bacteria recovered from all of the subgingival plaque samples with the possible exception of some penicillins.
Progression of periodontal disease in adult subjects in the absence of periodontal therapy.
Progression of periodontal disease in adult subjects in the absence of periodontal therapy was monitored in 2 populations. One group of 64 Swedish subjects (mean age 40.5 years at entry) with mild to moderate periodontal attachment loss was monitored for attachment level changes at baseline, 3 and 6 years. A second group of 36 Americans (mean age 34.3 years at entry) with advanced destructive periodontal disease was monitored for attachment level changes at baseline and 1 year. Of 4101 sites examined at baseline and at 3 years in the Swedish subjects, only 158 sites (3.9%) showed attachment loss of more than 2 mm. No measurable change was found in 1440 sites (35.1%). Of 4097 sites examined at 3 and 6 years, 67 sites (1.6%) showed attachment loss greater than 2 mm; 57.4% of sites showed no measurable change; and 19 sites (0.5%) showed a decrease in probeable attachment level of more than 2 mm. During the 6-year interval, 523 sites (11.6%) showed attachment loss of more than 2 mm; 20% of sites showed no measurable change and 11 sites (0.2%) showed more than 2 mm of attachment "gain". Approximately 50% of sites that showed no measurable change in the first 3-year period showed loss in the next 3 years. In contrast, of the sites which showed some level of attachment loss in the first period, approximately 2/3 showed no loss in the second monitoring period. Of 3210 sites monitored in the American subjects, 102 sites (3.2%) exhibited more than 2 mm of additional attachment loss; 26% of sites showed no measurable change and 138 sites (4.3%) showed a decrease in probeable attachment level of more than 2 mm. The association between attachment level changes and initial attachment level (baseline) was examined by regression analysis. The slopes of the regression lines for both populations were not consistent with a hypothesis that sites with more advanced attachment loss are more prone to additional destruction, in the absence of treatment, than sites with initially less attachment loss. In the American group, some sites with initially advanced attachment loss, exhibited a decrease in probing attachment level.
Statistical analyses of microbial counts of dental plaque.
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ELISA and conventional techniques for identification of black-pigmented Bacteroides isolated from periodontal pockets.
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T cell responses of periodontal disease patients and healthy subjects to oral microorganisms.
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A method for the geometric and densitometric standardization of intraoral radiographs.
The interpretation of dental radiographs for the diagnosis of periodontal disease conditions poses several difficulties. These include the inability to adequately reproduce the projection geometry and optical density of the exposures. In order to improve the ability to extract accurate quantitative information from a radiographic survey of periodontal status, a method was developed which provided for consistent reproduction of both geometric and densitometric exposure parameters. This technique employed vertical bitewing projections in holders customized to individual segments of the dentition. A copper stepwedge was designed to provide densitometric standardization, and wire markers were included to permit measurement of angular variation. In a series of 53 paired radiographs, measurement of alveolar crest heights was found to be reproducible within approximately 0.1 mm. This method provided a full mouth radiographic survey using seven films, each complete with internal standards suitable for computer-based image processing.
Bacterial interference in the oral ecology of Actinobacillus actinomycetemcomitans and its relationship to human periodontosis.
The plaque of 7 clinical health subjects was analysed for organisms inhibitory to the growth of A. actinomycetemcomitans strain Y4 on chocolate agar medium. Ten of the 11 sites harboured such organisms which constituted a median of 5.8 per cent of the total cultivable flora. Four to 30 per cent of the isolates in samples from eight sites in periodontitis were also inhibitory to strain Y4. By contrast, 15 of the 16 plaque samples from disease sites of 6 periodontosis (juvenile periodontitis) subjects showed no inhibitors. Four of 5 healthy sites sampled from 3 of the periodontosis subjects showed inhibitors in proportions similar to plaque from healthy subjects. The mother and 3 siblings of a subject with periodontosis lacked inhibitors in one or more plaque samples taken from their 1st molars. This work partially explains the basis for the localized pattern of destruction and the familial tendency of periodontosis.
Similarity of Wolinella recta strains isolated from periodontal pockets and root canals.
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Healing following surgical/non-surgical treatment of periodontal disease. A clinical study.
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"Critical probing depths" in periodontal therapy.
The present investigation was carried out on 15 individuals who were referred for treatment of moderately advanced periodontal disease. All patients were first subjected to a Baseline examination comprising assessment of oral hygiene and gingival conditions, probing depths and attachment levels. Following case presentation and instructions in oral hygiene measures, the patients were given periodontal treatment utilizing a split mouth design. In one side of the jaw scaling and root planing were performed in conjunction with a modified Widman flap procedure while in the contralateral jaw quadrants the treatment was restricted to scaling and root planing only. The period from initial treatment to 6 months after treatment was considered to be the healing phase and from 6-24 months after treatment the maintenance phase. During the healing phase the patients were recalled for professional tooth cleaning once every 2 weeks. During the maintenance phase the interval between the recall appointments was extended to 3 months. Reexaminations were carried out 6, 12 and 24 months after the completion of active treatment. The results revealed that treatment resulted in loss of clinical attachment in sites with initially shallow pockets, while sites with initially deep pockets gained clinical attachment. With the use of regression analysis "critical probing depths" were calculated for the two methods of treatment used. It was found that the critical probing depth value for scaling and root planing was significantly smaller than the corresponding value for scaling and root planing used in combination with modified Widman flap surgery (2.9 vs 4.2 mm). In addition, the surgical modality of therapy resulted in more attachment loss than the non-surgical approach when used in sites with initially shallow pockets. On the other hand, in sites with initial probing depths above the critical probing depth value more gain of clinical attachment occurred following Widman flap surgery than following scaling and root planing. The data obtained from the reexaminations 12 and 24 months after active treatment demonstrated that the probing depths and the attachment levels obtained following active therapy and healing were maintained more or less unchanged during a maintenance care period which involved careful prophylaxis once every 3 months. However, the data also disclosed that the level of oral hygiene maintained by the patients during healing and maintenance was more critical for the resulting probing depths and attachment levels than the mode of initial therapy used.(ABSTRACT TRUNCATED AT 400 WORDS)
An approach to the definition of periodontal disease syndromes by cluster analysis.
Clinical syndromes of 22 untreated patients with advanced destructive periodontal disease were analyzed using cluster analysis. Clinical characteristics coded for each patient included age, sex, measures of gingival inflammation, plaque, suppuration, pocket depth, attachment level, extent and pattern of bone loss, rate of change in pocket depth, and correlation coefficients between certain clinical measurements. Microbiologic features included darkfield enumeration of 10 morphologically distinct forms of organisms which were removed from the three sites showing the most advanced destruction in each patient, as well as viable counts of specific microbial groups from the same teeth using elective and selective media. Serum antibody levels were determined by the ELISA technique to 13 species of subgingival microorganisms. The Gower coefficient was used to estimate similarity between patients and clusters were formed using an average unweighted linkage sort. Three distinct patient clusters were observed with greater than 70% average intra-cluster similarity. One subject did not fall into any of the patient clusters. The features which defined and differentiated the clusters were found to include age of subject, extent and patterns of bone loss, percent of sites showing change in pocket depth and attachment level, percent of small motile rods, intermediate spirochetes and fusiforms and serum IgG levels against Bacteroides gingivalis, Selenomonas sputigena and a Wolinella strain.
Patterns of progression and regression of advanced destructive periodontal disease.
Attachment level at two sites on each tooth in 22 untreated subjects with existing periodontal pockets was measured every month for 1 year. Regression analysis was then applied to the data from each periodontal site to determine if statistically significant trends in attachment level change could be detected. 82.8% of the sites monitored did not significantly change during the year. 5.7% of the sites became significantly deeper and 11.5% of the sites became significantly shallower (P less than 0.01) during the period. Among those sites in which pocket depth increased, approximately half exhibited a cyclic deepening followed by spontaneous recovery to their original depth. In 15 of the subjects, sites were found which became significantly deeper while other sites within the same subject became significantly shallower. In six subjects, who might be considered to have an arrested form of periodontal disease, virtually no sites became deeper during the monitoring period whereas 11-36% of their sites became significantly shallower. The results of this investigation suggest that a dynamic condition of disease exacerbation and remission as well as periods of inactivity may be characteristic of periodontal disease.
Classification and identification of Actinobacillus actinomycetemcomitans and haemophilus aphrophilus by cluster analysis and deoxyribonucleic acid hybridizations.
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Humoral immune responses and diagnosis of human periodontal disease.
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