The Effect of Salivary Calcium and Fluoride Toothpaste on the Formation of KOH-Soluble Fluoride: In Vitro Study.

OBJECTIVE: The aim of this in vitro preliminary study was to assess the effect of smokers' saliva (assuming their higher calcium concentration) in combination with fluoridated toothpaste on the enamel uptake of alkali-soluble (KOH-soluble) fluoride. MATERIALS AND METHODS: Four enamel slabs were cut from each of 14 impacted third molars and randomly assigned into 4 groups. Unstimulated saliva samples were collected from two age and sex matched volunteers. One of the samples was taken from a heavy smoker and the other sample was taken from a non-smoker. Two groups (A and B) were shaken in saliva (A in smoker's saliva, B in nonsmoker's saliva) for 5 min and then shaken for 3 min in a toothpaste/deionized water slurry (1:3 w/w). One of the groups (group C) received no saliva treatment and was only shaken in toothpaste slurry for 3 min. The treatment was repeated after a 6-hour period. One of the groups (D) served as a control group with no treatment. RESULTS: Calcium concentration in the smoker's saliva was higher than in the nonsmoker's saliva. The enamel uptake of KOH-soluble fluoride in group A was significantly higher than that in the other two treatment groups, B and C. The enamel uptake of KOH-soluble fluoride in all 3 groups was statistically different from that in the control group. CONCLUSION: These results demonstrate that saliva collected from a heavy smoker, which had higher salivary calcium concentration, enhances enamel uptake of alkali-soluble fluoride and encourages us to conduct a large-scale study.

The cariostatic mechanisms of fluoride.

UNLABELLED: This article discusses the possible cariostatic mechanisms of the action of fluoride. In the past, fluoride inhibition of caries was ascribed to reduced solubility of enamel due to incorporation of fluoride (F-) into the enamel minerals. The present evidence from clinical and laboratory studies suggests that the caries-preventive mode of action of fluoride is mainly topical. There is convincing evidence that fluoride has a major effect on demineralisation and remineralisation of dental hard tissue. The source of this fluoride could either be fluorapatite (formed due to the incorporation of fluoride into enamel) or calcium fluoride (CaF2)-like precipitates, which are formed on the enamel and in the plaque after application of topical fluoride. Calcium fluoride deposits are protected from rapid dissolution by a phosphate -protein coating of salivary origin. At lower pH, the coating is lost and an increased dissolution rate of calcium fluoride occurs. The CaF2, therefore, act as an efficient source of free fluoride ions during the cariogenic challenge. The current evidence indicates that fluoride has a direct and indirect effect on bacterial cells, although the in vivo implications of this are still not clear. CONCLUSION: A better understanding of the mechanisms of the action of fluoride is very important for caries prevention and control. The effectiveness of fluoride as a cariostatic agent depends on the availability of free fluoride in plaque during cariogenic challenge, i.e. during acid production. Thus, a constant supply of low levels of fluoride in biofilm/saliva/dental interference is considered the most beneficial in preventing dental caries.

Pathophysiology of osteonecrosis of the jaw in patients treated with bisphosphonate.

Apart from the well-known mechanism of bisphosphonates' cellular effect, embryonic development and the specific features of alveolar bone homeostasis have been discussed. The unique ethiopathogenic mechanism which relates osteonecrosis of the jaw and bisphosphonates treatment has not been explained. The emphasis lies on the toxicological effects of bisphosphonates on the physiology of the alveolar bone and on the lasting effect of tooth extraction followed by an infection of the extraction wound and consequent progression into deeper layers of osseous tissue. Epithelial infection includes microbiological findings of Actinomyces species. The risk is pronounced in oncological patients treated with bisphosphonates intravenously in relatively large doses and during a longer period of time, especially with highly potent nitrogen-containing bisphosphonates pamidronate and zoledronate. This review of bisphosphonate-related osteonecrosis of the jaw stresses the significance of some other risk factors (corticosteroids, chemotherapy, tumour tissue etc.) of necrosis development--more precisely of osteomyelitis of the jaw if the microbiological component of the diseases has been taken into account, while the role of the bisphosphonates becomes minor. There is no gold standard for the treatment of jaw osteonecrosis; rather, palliative and minimally invasive treatment is applied, without subsequent oral surgical interventions. Since there is a significant risk of jaw osteonecrosis in oncological patients, the level of oral health is an important factor for the indication of intravenous bisphosphonates treatment.

Antimicrobial effect of different brushing frequencies with fluoride toothpaste on Streptococcus mutans and Lactobacillus species in children with fixed orthodontic appliances.

OBJECTIVE: To evaluate the antimicrobial effect of different frequencies of brushing with fluoride toothpaste on the levels of salivary mutans streptococci and lactobacilli in children undergoing fixed orthodontic treatment. METHODS: The study included 22 patients scheduled for fixed orthodontic therapy distributed between 2 groups with different hygiene regimes. All the subjects received identical braces, bands, and brackets bonded with the same material. Stimulated saliva samples were obtained before placement of the appliance and at 6, 12, and 18 weeks during the therapy. Saliva samples were cultured on selective microbial agar for the detection of microorganisms. RESULTS: Salivary mutans streptococci were significantly suppressed throughout the experimental period in the group that brushed 4 times a day as compared to the group that brushed twice a day. Salivary lactobacilli were not significantly affected by the frequency of brushing with 0.32% sodium fluoride (NaF) toothpaste. CONCLUSIONS: The use of 0.32% NaF-containing toothpaste more than 3 times a day has effective antimicrobial activity on mutans streptococci but not lactobacilli in the saliva of children with fixed orthodontic appliances.

Salivary calcium concentration and periodontal health of young adults in relation to tobacco smoking.

PURPOSE: To evaluate the effect of tobacco smoking and salivary calcium on the periodontal status of young adults. MATERIALS AND METHODS: Plaque index, gingival bleeding on probing, supragingival calculus, DMFT index, salivary flow, pH and salivary calcium in unstimulated salivary samples were recorded in smokers and nonsmokers. RESULTS: There were no significant differences between smokers and nonsmokers with respect to salivary flow (P = 0.08) and calcium level (P = 0.09). Significant correlations (P < 0.05) were found between a higher calcium level and higher probing depth (r = 0.60), higher number of teeth with probing depth of more than 4 mm (r = 0.70), greater clinical attachment level (r = 0.49) and lower number of teeth bleeding on probing (r = -0.50). CONCLUSION: Moderate smoking of tobacco cigarettes in young healthy subjects may not have a significant impact on salivary flow or calcium concentrations in unstimulated saliva, but an association exists between an increased level of salivary calcium and development of periodontal disease.

Physical fitness course in the dental curriculum and prevention of low back pain.

Physical and psychosocial stressors in dental schools are associated with adverse health outcome, including low back pain. The aim of this study was to evaluate the physical fitness course included in a dental school's curriculum with regard to prevention of low back pain. Ninety first-year and sixty-two final-year dental students completed an anonymous questionnaire on physical fitness habits and low back pain. Fifty voluntarily participated in the Åstrand bicycle ergometer test. The questionnaire revealed that 37 percent of the students have weekly physical exercise only during the physical fitness course included in the curriculum and 62.5 percent of the students reported low back pain. Final-year dental students had significantly more low back pain than first-year dental students (r=0.21, χ(2)=7.91, p=0.005). Female students had significantly more low back pain than male students (r=0.28, χ(2)=6.61, p=0.0101). The Åstrand test revealed that students who attended the physical fitness course had significantly better physical fitness (p=0.008) than those who did not. Students who exercised more regularly had significantly less low back pain (r =-0.19, χ(2)=11.89, p<0.01) than those who did not. We conclude that participation in a physical fitness course leads to improved low back health for dental students and may prevent low back pain among final-year dental students.