A variety of indices has been developed for the quantitation of dental plaque. The aim of this study was to determine the correlation between the Löe plaque index and the number of bacteria on the same tooth. Furthermore, the effect of plaque accumulation on the salivary counts of some dental plaque organisms was estimated. Twenty volunteers were asked to abstain from all oral hygiene for a one-week period. Clinical indices and bacteriological samples were taken at the start and at the end of the experimental period. After an interval of seven days, the experiment was repeated. The relationship between the Löe plaque index and the total bacterial counts on the same area of the tooth was found to be highly significant. After seven days without oral hygiene, the total counts and the Actinomyces viscosus/naeslundii and Streptococcus sanguis counts in dental plaque had increased by approximately two log units, while the Streptococcus mutans counts had increased by more than one log unit. The large increase in the number of bacteria on the teeth was reflected in the salivary counts of the Actinomyces species, but not in the S. sanguis or S. mutans counts. This was due to differences in ecological habitats of these species in the mouth. Highly significant correlations were found between the S. mutans level in dental plaque and the salivary level, and between the S. mutans counts of the subjects in the first and second trials of the experiment.

No abstract

Previous experiments have shown that daily use of 1% chlorhexidine gel strongly reduced caries development in the abutment teeth under overdentures. The present experiment was designed to determine whether intermittent application of chlorhexidine, either in a varnish or in a gel, might be used as an alternative preventive method, less demanding for the patient. To this end, 31 patients were distributed among four treatment groups, with the number of mutans streptococci in plaque and saliva used as a balancing criterion. The treatments consisted of a single application of 40% chlorhexidine varnish, daily application of 1% chlorhexidine gel for one week, or the corresponding placebo treatments with varnish or gel without chlorhexidine. Patients were re-called for bacteriological and clinical examination at various intervals during an eight-week period following treatment. Chlorhexidine varnish and chlorhexidine gel applications significantly suppressed mutans streptococci on the abutment teeth for four and eight weeks, respectively. In agreement with earlier findings, the numbers of Actinomyces viscosus/naeslundii in plaque were significantly increased after chlorhexidine varnish treatment. The chlorhexidine gel reduced plaque accumulation and gingival bleeding for one week but had no long-lasting effect. The results seem to justify a long-term clinical test of intermittent chlorhexidine applications as an alternative for daily use in patients with overdentures.

The retreatment need was assessed in 148 patients wearing 125 overdentures in the mandible and 56 in the maxilla. The total number of abutment teeth was 512. During the evaluation period 44 abutments were extracted. The endpoints of the survival analysis after 6 yr were 89%, taking the loss of all abutments as the failure criterion for overdentures. During the clinical examination it was found that 31% of the abutments needed treatment while the retrospective part showed a mean yearly restoration need of 17.5%. Caries was the most important reason for retreatment. These data demonstrated that patients with overdentures should be regarded as high risk patients for retreatment of abutments. Therefore a stringent maintenance program, including regular recall appointments and the application of a preventive regimen, is desirable.

In this study, a mouthrinse containing calcium lactate was tested for its effect on the accumulation of dental plaque and on the concentrations of calcium and phosphorus therein. Human volunteers rinsed four times per day with a calcium lactate (165 mmol/l) solution for 1 week. Plaque samples, collected 16 h after the last rinse, were analyzed chemically. Calcium lactate rinses had no effect on the plaque score, but resulted in approximately twofold increases of calcium and phosphorus in plaque. The incorporation of monofluorophosphate (5 mmol/l) into the rinsing solution failed to show any significant influence on calcium, phosphorus, and fluoride levels in plaque. Increased mineral deposition in the plaque may provide an explanation for the reduced caries development earlier observed in rats fed a diet containing calcium lactate.