No abstract

Polydimethylsiloxane (silicone oil) has an extremely low surface tension: It spreads over solid surfaces and forms a tenacious film which is hydrophobic and water-repellent. It is known that this liquid binds to hydroxyapatite and to dental enamel and changes the properties of these solids. It has been suggested that silicone oil may be applied to teeth and serve as a reservoir of lipid-soluble antibacterial substances which presumably will be slowly released into saliva due to their low solubility in water. The present paper reviews recent papers where this hypothesis is tested in vitro and in vivo. It was first shown that test tubes treated with the combination silicone oil and the lipid-soluble agent triclosan acquired a layer which inhibited bacterial growth in a culture of Streptococcus sobrinus (OMZ 176) which was grown in sucrose. Both growth in the medium and polysaccharide adsorption to the glass wall were inhibited. Silicone oil alone inhibited polysaccharide adsorption to some degree, whereas the growth in the medium was not affected. In a similar clinical plaque-inhibition study, topical application of silicone oil/triclosan to the teeth of a test panel showed marked plaque inhibition, particularly giving an increased number of teeth with scores of 0 (no plaque). In a study where silicone oil and triclosan were incorporated into a toothpaste, improved gingival health was observed after a period of one month. It is concluded that the use of silicone oil/triclosan in the manner described above represents a new principle in preventive dentistry. The results obtained seem to warrant further experiments with this combination.

Dental calculus itself is not thought to affect gingival health, but its rough and porous surface retains plaque better than a calculus-free surface. In a population with a high degree of supragingival calculus, the effect of toothbrushing after a careful professional prophylaxis (group A) has been compared with the effect of toothbrushing as the sole oral hygiene aid (group B). The subjects in this comparison were Indonesian soldiers, 20-25 years of age, none of whom had pathological pockets (CPITN less than or equal to 2), but all had large amounts of calculus. They had no experience of modern oral hygiene practice but were given individual instruction in toothbrushing at the start of the study and were provided with toothpaste and toothbrush. Removal of calculus in group A took an average of 1 h per subject by an experienced clinician. Gingival health in both groups improved after 2 months: group A from 63% to 34% bleeding points and group B from 61% to 36%. There was thus no obvious benefit from the professional prophylaxis received by group A. The results are particularly relevant for populations in which professional prophylaxis is not normally available. However, they were obtained in a group of young, healthy individuals and may not be extrapolated to older and less healthy populations or to individuals with deep periodontal pockets. The improvement of gingival health through toothbrushing, in spite of the presence of calculus, supports the contention that plaque, rather than calculus as a non-inflammatory scale, provides the pathogenic potential.

This article reviews a new concept of pellicle formation based on recently published data, and some experiments concerning the role of the pellicle in relation to calculus formation. There are strong indications that the pellicle consists of a multilayer of globules with a diameter of from 20 to 300 nm. These globules have a raspberry-like surface with clusters of smaller globules which are bound together by calcium, probably by bridging. The globules have negatively charged surfaces and hydrophobic interiors and are very similar to the micelles present in milk. It was shown in the present experiments that the pellicle inhibited seeded precipitation of calcium phosphates on enamel in a saturated solution. It was further shown that several proteolytic enzymes were able to release peptides from both milk micelles and from salivary globules, and that this treatment eliminated or reduced the inhibiting effect of the pellicles with regard to precipitation of calcium phosphates on enamel. It is suggested that this may be related to calculus formation in vivo, and that the pellicle normally inhibits calculus formation, but that proteolytic enzymes from bacteria in the oral cavity degrade the pellicle and cause it to lose its inhibiting effect.

Polydimethylsiloxan (silicone oil) adsorbs to solid surfaces and to teeth because of its low surface tension, forming a thin, resistant layer. Triclosan is a lipidsoluble, antibacterial substance which is added to toothpastes and mouthwashes to inhibit plaque. Triclosan can be dissolved in silicone oil, conferring an antibacterial property on the layer of silicone oil which forms on solid surfaces. The aim of the present study was to determine whether a toothpaste containing triclosan/silicone oil has any effect on established gingivitis in a test panel of 33 teenagers. This toothpaste and a placebo paste were randomly distributed to the panel, and the number of gingival bleeding points was recorded. No instruction in oral hygiene was given. The panel was then examined 4 wk later and the number of bleeding points again recorded. It was found that the reduction in bleeding points was significantly higher in the group which had used the triclosan/silicone oil paste than in the placebo group. Deposition of a lipid‐soluble, antibacterial agent in a layer of silicone oil which adsorbs to the tooth surfaces because of its physical properties represents a new and promising principle in preventive dentistry.