Lee R. Brown

Prevention of Xerostomia-Related Dental Caries in Irradiated Cancer Patients

Three caries preventative regimens: oral hygiene ; oral hygiene and topical fluoride; and oral hygiene, topical fluoride, and sucrose restriction were evaluated in patients with cancer given xerostomia-producing radiotherapy. The oral hygiene-fluoride gel combination was remarkably effective in protecting these high risk patients from caries, regardless of the cariogenicity of the diet.

Effect of Radiation-Induced Xerostomia on Human Oral Microflora

A longitudinal study was performed to assess the effects of radiation-induced xerostomia on the human oral microflora. Pronounced microbial population shifts were found in each of five intraoral sites tested. Cariogenic microorganisms gained prominence at the expense of noncariogenic microorganisms in concert with the saliva shutdown. These changes occurred before the onset of clinical caries irrespective of whether or not a topical fluoride gel was used as a caries preventive.

Radiation‐induced xerostomia in cancer patients. Effect on salivary and serum electrolytes

Saliva and serum electrolyte concentrations were monitored in 30 patients given a course of xerostomia‐producing cancer radiotherapy. The mean flow rate of stimulated whole saliva decreased 83.3% during a 6‐week treatment period. The striking reduction in saliva output was accompanied by significant increases in saliva Na+, Cl−, Ca++, Mg++ and Prot.− concentrations and by a decrease in saliva HCO  3− content. The xerostomic saliva was more concentrated and had a greater salinity than the pretreatment saliva in each instance. In contrast, none of the serum electrolytes measured was significantly altered by the subtotal salivary shutdown.

Comparison of Streptococcus mutans Concentrations in Non-banded and Banded Orthodontic Patients

The effect of orthodontic banding on the prevalence of Streptococcus mutans in plaque was evaluated by comparisons between patients wearing bands and patients just prior to banding on the basis of treatment and/or dental caries history. Banded patients had significantly higher levels of S. mutans in plaque than did their non-banded counterparts. Regardless of banding, patients with a history of caries had significantly higher levels of S. mutans in plaque and greater numbers of S. mutans-infected sites than did caries-free patients. Caries-free banded patients had more S. mutans-infected sample sites than did the caries-free non-banded group.

Interrelations of Oral Microorganisms, Immunoglobulins, and Dental Caries Following Radiotherapy

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.

The effect of radiation-induced xerostomia on saliva and serum lysozyme and immunoglobulin levels.

Saliva and serum lysozyme, immunoglobulin, albumin, and total protein levels were monitored in thirty patients with cancer of the head or neck before, during, and after radiotherapy and compared with those of a group of non-irradiated noncancer control subjects. The mean volume-based saliva lysozyme and total protein concentrations were significantly higher in the cancer patients before radiotherapy than in the control group. During radiotherapy, the mean volume-based concentrations of all protein components assayed increased as the saliva flow rate decreased. Protein-based ratios of saliva albumin, IgG, and lysozyme and the ratio of IgG/IgA increased as the xerostomia intensified. Ratios of saliva total protein and IgA to flow rate paralleled the flow rate decrease. Such increased concentrations in saliva immunoproteins were offset, however, by a greater than 93 per cent reduction in total saliva output. This reduced saliva output, therefore, resulted in an immunoprotein deficit. There were no significant differences between the mean serum lysozyme levels of the cancer and control groups at any point of comparison. The mean serum immunoglobulin concentrations in the cancer patients before radiotherapy were significantly higher than those in the control group. During radiotherapy, there was a decrease in the mean serum total protein, albumin, and immunoglobulin levels which reverted toward the pretreatment values during the postirradiation period.

Comparison of the Plaque Microflora in Immunodeficient and Immunocompetent Dental Patients

The nature and extent of the immune dysfunctions in 20 immunodeficient patients, as well as the immunocompetence of 22 control subjects, were verified by cell-mediated responsiveness and immunoglobulin quantitations. Comparisons of the microbial composition of supragingival plaque between the two populations showed that a greater number of immunodefcient than control subjects harbored Candida sp. and Staphylococcus sp. Conversely, a lower number of immunodeficient than control subjects harbored Streptococcus mutans. Also, patients with immune dysfunctions had a lower dental caries experience than their immunocompetent counterparts.

Comparative Effect of SnF2, NaF, and SnCl2 on the Growth of Streptococcus mutans

The inhibitory effects of NaF, SnF2, and SnCl2 were compared in vitro on the growth of Streptococcus mutans NCTC #10449. Sodium fluoride arrested growth at 300 and 600 ppm F (while SnF2 suppressed the rate of growth at 75 ppm F), showed some bactericidal activity at 150 and 300 ppm F, and was totally bactericidal at 600 ppm F. The greater inhibition by SnF2 suggests an additive effect of Sn2+. As a measure of a fluoride-free Sn2+ solution, SnCl2 was inappropriate since most of the tin present, at a neutral pH, was Sn4+. The influence of pH was particularly noteworthy with SnF2 at 600 ppm F, where a total bactericidal effect was observed within four h at pH 5.9, while viable cells were still recoverable from four to 40 h with SnF 2 at pH 7.2.

Survey of Microorganisms for Calcification in a Synthetic Medium

Fourteen microorganisms, oral isolates from man or marmoset, were examined for calcification in a synthetic medium. The medium was essentially identical to that in which Bacterionema matruchotii acquires intracellular apatite. Four of the microorganisms, Escherichia coli, Alcaligenes marshalli, Aerobacter cloacae, and Proteus mirabilis, developed intracellular calcifications.

Fluoride Resistance and Adherence of Selected Strains of Streptococcus mutans to Smooth Surfaces After Exposure to Fluoride

The fluoride resistance and smooth surface adherence characteristics of Streptococcus mutans were examined using tooth model and radioactive cell assays. Resistance to 600 ppmF by S. mutans isolated from the plaque of radiation-induced xerostomia patients receiving daily topical applications of a caries preventive 1% NaF gel was transient. Resistance induced in vitro in two strains of S. mutans by exposure to gradually increasing levels of NaF was apparently permanent. Smooth surface adherence by both fluoride-sensitive and -resistant strains of S. mutans 6715 in a tooth model system was slightly diminished by 1% NaF gel. Fluoride-resistant strains retained 89 to 93% of their adherence capability in 600 ppmF, as determined by the cell radiolabeling assay.