Journal of Dental Research

The anticaries effect of repeated toplications with APF gel was assessed in the primary dentition of 2-6-year-olds after 8, 18 and 28 months. Frequent, but less than daily, topical fluoride therapy appeared to have little effect in pre-school children consuming water-borne fluoride and receiving other traditionally recommended modalities of prevention.

The color stability of polyvinyl chloride, polyurethane, and silicone polymers for maxillofacial applications was determined after accelerated aging using reflectance spectrophotometry. On the basis of color stability after accelerated aging, and ease of processing, several silicone materials were the most promising.

It is shown that the creep behavior of a commercial dispersant-amalgam containing copper is improved by the addition of a manganese-containing alloy. This improvement is apparently obtained without any serious changes in corrosion resistance, provided that no more than 20% of the Mn alloy is added.

The effects of thickness, background color, specular reflection, and surface roughness on the color of five commercial restorative resins were studied by reflection spectrophotometry. As thickness increased, values of luminous reflectance and excitation purity increased for a black background but decreased for a white background. Opacity increased dramatically as thickness increased from 1.3 to 3.9 mm.

Of 42 head and neck cancer patients with radiotherapy-induced xerostomia, 36 survived to permit a postirradiation caries evaluation. Twenty-three developed an average of 17.6 caries lesions and 13 had no new lesions within 30 months postirradiation. All caries-inactive patients had been initially assigned to daily self-application of a 1% sodium fluoride gel. The preirradiation caries experience and the oral microbial profile were comparable in both groups. After tumoricidal irradiation, the mean plaque increase of Streptococcus mutans was 25 times greater in the caries-active than in the caries-inactive group. Postirradiation caries was also associated with increased plaque Lactobacillus sp, Candida sp, and Streptococcus sp, and serum IgD and IgG concentrations. Conversely, plaque Staphylococcus sp, Streptococcus salivarius, and Veillonella sp and saliva IgA concentrations were significantly higher in the caries-inactive than in the caries-active group. Both groups demonstrated decreases in plaque Streptococcus sanguis, Neisseria sp, Fusobacterium sp, and Bacteroides sp.

A technique utilizing sodium deoxycholate to remove junctional epithelial cells from the epithelial attachment zone is described. Light and electron micragrayhs show a simalarity in size and appearance between the extracetlutar attachment substance in controls and the extracellular substance which remains on cementurn previously in contact with junctional epithelium.

Two studies were conducted to explore the effects of twice daily topical applications of NaF, SnF ₂, and an amine fluoride at equivalent fluoride concentrations (0.1%) upon plaque and gingivitis in the dog. Although some trends toward modest benefits were noted in certain instances, none of the agents exerted a significant effect upon either parameter.

In vivo strain gauge analysis demonstrated that tensile bone strain is transmitted along the cranial vault to the parasagittal region during isotonic temporalis contraction. This strain is sufficient to cause measurable separation of the sagittal suture, and thus could influence growth at the sutural margins.

Adsorption of Streptococcus mutans on hydroxyapatite and chemically treated hydroxyapatite was studied. Zeta potentials of the surfaces were measured. Chemically treated hydroxyapatite gave higher ζ potentials and lower S mutans adsorption.

A new ceramic form of hydroxylapatite and enamel were found to behave similarly in regard to their acid dissolution behavior in the presence and absence of topically applied fluoride. Discrepancies between the two materials can be explained by morphological differences between the rough enamel and smooth ceramic particles.

Silver cations generated by passing low intensity direct current through pure silver electrodes were found to be sufficiently antibacterial to cause sterilization of samples of infected dentin. The optimal procedure involved a 5 μA current applied for 20 minutes with the anode then left in contact with the sample. Minimal inhibitory concentrations of electrically generated silver ions for representative oral bacteria were essentially equal to those for silver ions added as nitrate or fluoride salts, and medium constituents, including sodium thioglycolate, antagonized antibacterial action. A major advantage to the use of the electrode method is that it allows for continuous, focal application of antibacterial silver cations.

The affinity of some bacterial polysaccharides for hydroxyapatite was investigated. Water insoluble polysaccharide production by bacteria was inhibited by the presence of NaF in the growth medium, while the water soluble fraction was unaffected. The adsorption of the bacterial polysaccharide on hydroxyapatite decreased with decreasing levels of the water insoluble fraction. It is suggested that NaF can inhibit bacterial attachment and caries by interfering with bacterial attachment through reducing the production of water insoluble polysaccharide.

Realization of the important role of Streptococcus mutans in the initiation of dental caries has resulted in extensive studies of all its biologic characteristics. The ultimate goal is to control or eliminate it from the oral cavity. One means of accomplishing this is to reduce or eliminate its carbohydrate source. This study reports those carbohydrates which Streptococcus mutans cannot metabolize.

Systematic investigation of the chemical reaction of a slurry of SnF2, Ca₁₀(OH)₂(PO ₄)₆, and H₂O shows that products other than CaF2 are determined by the relative concentrations of the reactants. In addition to Sn₂OHPO₄, and Sn₃F₃PO ₄, a previously unreported compound, Ca(SnF₃)₂, has been observed as a product of the reaction.

Applications of APF and NaF solutions to extracted human teeth reduced the extent of enamel subsurface demineralization induced by colonization of S. mutans but were ineffective against demineralization by acid lactate buffers. It is concluded that the CaF ₂ formed on the tooth surface during the treatment is responsible for the protection observed.