A histochemical study of the effects of high doses of sodium fluoride on dipeptidyl peptidase II activity in the rat incisor ameloblast

Female Wistar rats, 3 weeks old, were given sodium fluoride in saline solution (isotonic) by intraperitoneal injection at a dose of either 0, 10 or 20 mg per kg body weight. This treatment was given 9 times over 4.5 days. After fixation by perfusion and demineralization in neutral EDTA, hemi-mandibles were sectioned in a cryostat. Sections were stained for dipeptidyl peptidase II activity, using the specific substrate Lys-Ala-MNA and the coupler Fast Blue B for histochemical localization. Staining indicative of dipeptidyl peptidase II was found in the enamel organ of the incisor, particularly in cells of the stratum intermedium and in both secretory and maturation ameloblasts. This staining was markedly reduced in ameloblasts of rats given either 10 or 20 mg sodium fluoride per kg body weight.     

Denture base acrylic reinforced with high modulus fibre

Dentures are frequently fractured owing to the poor fracture resistance of Denture Base Acrylic. This experiment was designed to compare the transverse strength of samples of conventional and cross-linked acrylic with samples containing various proportions of one of two high modulus fibres. The stiffest and strongest specimens were those of the conventional acrylic and all the reinforced specimens were significantly weaker. The reason for this appears to be failure to achieve true adhesion between the fibre and the matrix resulting in the layers of fibre separating the matrix into layers of narrow cross-section.     

A comparison of the sealing properties of different retrograde techniques: an autoradiographic study

Single-rooted teeth were instrumented and filled in vitro with a lateral condensation of gutta-percha with sealer. Following obturation, the tooth apices were treated by various retrograde procedures. The teeth were then coated with ethyl acetate, immersed in 45Ca solution, washed, and sectioned, and autoradiographs were used to compare the leakage of the various techniques. Statistical analysis indicated that lateral condensation produced a significantly better seal than any retrograde technique tested except retrofilling with Super EBA cement and that a significantly worse seal was obtained with amalgam retrofill when compared to all retrograde techniques except cold-burnished gutta-percha following apicoectomy. No significant difference existed between other group combinations.     

Salivary concentrations of steroid hormones in males and in cycling and postmenopausal females with and without periodontitis

Concentrations of testosterone, dehydroepiandrosterone, eslradiol, progesterone, 17α-hydroxyprogesterone, and cortisol were measured in the saliva by radioimmunoassay. Saliva from male and cycling and postmenopausal female patients with and without periodontitis was studied.
It was found that salivary concentration of progesterone was increased in all patients with periodontitis. While testosterone was significantly increased in the female diabetic and non-diabetic patients with periodontitis, no difference in its concentration was found in the saliva of non-diabetic males with and without periodontitis. Salivary dehydroepiandrosterone was also increased in postmenopausal females with periodontitis. In contrast, estradiol was significantly decreased or not measurable in all patient groups with periodontitis. The concentration of cortisol and 17α-hydroxyprogesterone showed no significant differences in postmenopausal patients with and without periodontitis. In addition, the salivary concentration of all hormones in postmenopausal females showed circadian variation. Moreover, results obtained in postmenopausal and ovariectomized females provided evidence for extragonadal production of sex steroid hormones in postmenopausal females.
The present results suggest that there is a relationship between the altered production of sex steroid hormones and the incidence of periodontal pathology.