The protocol for this study was designed to evaluate the effects of supportive recall treatments provided with different frequencies, viz. at 3-, 6-, 12- and 18-month intervals. The subjects for the study were recruited from patients attending a public, general dentistry clinic. Prior to baseline, the subjects were given necessary dental treatments to provide a proper baseline for the study. Baseline, intermittent and final recordings included scores of dental plaque, bleeding on probing, probing depth and probing attachment level. Results were evaluated statistically by intergroup comparisons of changes for the various parameters from baseline to final examination after 5 years. The analyses showed some advantage to shorter recall intervals for plaque and bleeding scores. Although not statistically significant, there was a trend suggesting some rebound of sites > or =6 mm deep at the end of the study for the 18-month group, but not for the other groups. Similarly, there was a trend that the 18-month group showed a higher percentage of buccal/lingual furcation sites with attachment loss > or = 1.0 mm than the other groups. Apart from these trends, the analyses failed to demonstrate differences between the groups for either changes of probing depths or probing attachment levels. The negative observations included identification of individuals with 'disease progression' in the various groups, using a series of arbitrary definitions for this parameter. The results of this trial suggest that recall intervals extended to a year may be acceptable for the purpose of reducing periodontal disease progression in individuals with a history of limited susceptibility to the disease.

Simonsson T, Ronstrom A, Rundegren J, Birkhed D: Rate of plaque formation -some clinical and biochemical characteristics of "heavy" and "light" plaque formers, Scand J Dent Res 1987; 95: 97-103, Abstract -The purpose of the present study was to give a clinical and biochemical characterization of two groups of individuals witb different rates of plaque formation. From 133 individuals, 9 "heavy" and 10 "light" plaque formers were selected. The mean plaque index after 3 days of plaque accumnlation, on buccal surfaces of premolars and first molars, was 2,6 for the "heavy" and 0,6 for tbe "iighl" plaque formers. The foUowing variables were determined: periodontal status, DFS, dietary habits, salivary secredcn rate and buffer effect, S, mutans and lactobacillus counts in saliva, salivar)' content of IgA, lactoferrin, lactoperoxidase and lysozyme, sahva-induced aggregation of certain oral streptococci, gel electrophoresis of saliva, amino acid composition of saliva and tbe acquired pellicle and retention depth of the dentogingival area. Comparing the two groups of plaque formers, statistically significant diiferences were found for the following three variables: parotid saliva-induced aggregation of a strain of S, sanguis, content of glutamic acid in the acquired pellicle and retention depth of the dentogingival area for maxillary premolars. Large variations for all studied variables were found, both within and between the groups. Several factors may be involved in plaque formation and none of the studied variables alone could explain the large difference in the amount of plaque formed after 3 days between the "heavy" and "light" plaque formers.

This study was designed to gain further information on early plaque formation using a previously described method employing plastic films for the collection of the initial deposits. To prevent the loss of loosely adhering material during processing of dental plaque for microscopic observation, the method was further developed by introducing an agar protection of the deposits formed on plastic films prior to fixation, dehydration and embedding procedures. Four human subjects with healthy gingiva developed microbial plaque during periods of 4 and 8 hours on plastic films applied on the buccal surfaces of premolars and cuspids. After 4 hours the plastic films were covered by a surface coating of an acellular material in or on which bacteria, epithelial cells and leukocytes were observed. The microorganisms were almost exclusively identified as Gram‐positive cocci. The deposit in the 8 hour samples exhibited the same general morphology, but with more cellular components. Bacterial aggregation to each other or to epithelial cells was frequently mediated by filamentous appendages on the bacterial cell walls. The frequent observation of a close association between bacteria and epithelial cells suggests that the latter may play an important role as a vehicle for transporting microorganisms to the solid surfaces in the mouth in the initial stage of plaque formation.

No abstract

The presence of Strep, sanguis and Strep, salivarius during early plaque formation on plastic films has been studied in humans. The numbers of other cultivable bacteria were also evaluated. In 12 adults with clinically healthy gingiva, a thin transparent plastic film was applied to the buccal stirface of one of the premolars in either the upper or the lower jaw. The films were left in place for different time intervals, from 10 seconds to 240 minutes. Samples for bacterioiogic analysis were taken from a defined area of each film located iust coronally to the gingival margin. At each time interval, a saliva sample was also taken from each individual. The various samples, showed bacterial growth at each time interval, immediately after salivary contamination of the films. Strep, sanguis predominated over Strep, salivarius while in the corresponding saliva samples these proportions were reversed. During the experimental period of 240 minutes the presence of Strep. sanguis on the film increased with increasing time, while the corresponding figures for Strep, salivarius were low. The film technique used seemed to provide an adequate method for studies of early plaque formation,