Filler systems based on calcium metaphosphates

Calcium metaphosphates (CMP's)--a unique class of phosphate minerals possessing polymeric structures, [Ca(PO3)2]n, and having refractive indices of approximately 1.54-1.59-- are optically compatible with resins such as BIS-GMA. In this study, several types of CMP's were prepared and evaluated for their potential as fillers for visible-light-activated (VLA) dental composites. The vitreous (V) and beta-crystalline forms of CMP were prepared by controlled thermolysis of monocalcium phosphate monohydrate, Ca(H2PO4)2.H2O. Hybrid fillers were also prepared by thermal methods. Fillers, characterized by IR spectroscopy and optical microscopy, were prepared in several size ranges (e.g., 1-100 microns). VLA composites were formulated by use of both untreated and surface modified CMP's. V-CMP and its hybrids yielded composites which expanded when stored in water but were of low strength, e.g., diametral tensile strength, (DTS) = 8 MPa. beta-CMP composites were more moisture-resistant, had higher DTS's (from 12 to 33 MPa), and showed a tendency to arrest brittle fracture. These novel fillers have potential uses in resin-based materials such as dental composites, cements, and adhesives.     

A 5- and 8-year clinical evaluation of a posterior composite resin

Class I and II posterior composite resin (Ful-Fil) restorations were placed and were clinically evaluated, according to the US Public Health Service criteria, at baseline, 6 months, 5 years, and 8 years. At 5 years/8 years, alpha scores were assigned to the following percentages of restorations: 16%/31% for color match; 65%/62% for marginal discoloration; 74%/54% for cavosurface marginal discoloration; 100%/100% for axial contour; and 81%/65% for anatomic form. At 5 years/8 years, 56%/33% of Class II restorations had tight proximal contacts; 45%/44% had light contacts; and 0%/22% had no contacts. Transient postoperative sensitivity was reported in 6% of the restorations. Indirect evaluation indicated that there was an average of 64 +/- 35 microns of wear at baseline (because of overfinishing), 105 +/- 67 microns at 6 months, 217 +/- 76 microns at 5 years, and 253 +/- 82 microns at 8 years. At 5 years, three of the restorations, and at 8 years, four additional restorations, were clinically unacceptable because of recurrent caries and/or excessive wear. Final success rates of 90% and 77% at 5 and 8 years, respectively, were calculated.     

Social class, parents' education and dental caries in 3- to 5-year-old children

The caries prevalence of 1273-, 4- and 5-y-old white children was determined with mirror and probe under natural light at mother and child clinics. The social class of the family, the educational level of the mother and that of the father were determined from a questionnaire filled in by the accompanying adult at the time of examination. Both social class and parent's education had a statistically significant influence on the caries prevalence: those in the lower social classes and with parents without tertiary education had a much higher prevalence of caries.     

Effect on the incidence of oral submucous fibrosis of intervention in the areca nut chewing habit

Incidence of oral submucous fibrosis was calculated from a 10-yr prospective intervention study of 12,212 individuals with a strong component of health education on tobacco and area nut chewing. Based on 11 new cases among 6341 chewers, the annual incidence was 8.0 per 100,000 among men and 29.0 for women. An earlier 10-yr follow-up study, with no intervention component, served as control. Based on 11 new cases among 3,809 chewers, the annual incidence was 21.3 per 100,000 for men and 45.7 for women controls. Although the decrease in the incidence in the intervention cohort was not statistically significant due to small number of cases, the results underscored the causal role of areca nut chewing and indicated the potential for primary prevention of oral submucous fibrosis.     

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.     

铸造义齿中网状支架的设计

铸造义齿中网状支架的设计李景辉，宋培智，陈官辉，季秋杰，卢玉春，高银凤在可摘局部义齿修复中，网状支架的合理设计既增加了义齿的强度，又具有传递咬力、分散力、保护口腔内软硬组织的功能［１］。常用形态为园孔形、方格形、楼梯的，网状形、三角形、倒锥形、栅栏形...