Experimental study in the dog of the non-active role of the tooth in the eruptive process

The role of the tooth in eruption was studied radiographically and histologically after experimental manipulations of the crowns of permanent mandibular premolars in dogs. Crowns were removed and dead crown shells or metal or silicone replicas were substituted into dental follicles just prior to scheduled eruption. These replacements erupted on schedule after formation of the usual eruption pathways and formation of trabecular bone from the base of the bony crypt. Removal of crowns, but without adding replacements, also exhibited these same hallmarks of eruption. We conclude that tooth eruption is a series of metabolic events in alveolar bone characterized by bone resorption and formation on opposite sides of the dental follicle and the tooth does not contribute to this process.     

Influence of the thyroid upon the glycosaminoglycans in the salivary glands in the rat

The glycosaminoglycans of the salivary glands were studied in male rats 2 months after radiothyroidectomy, and after the daily administration of 0.1 and 1.0 μg of sodium-1-triiodothyronine to radiothyroidectomized rats for 1 month. Total uronic acid concentration was determined in the salivary glands. Chromatographie separation of the uronic acid fractions was performed on cellulose microcolumns. Radiothyroidectomy increased and the administration of triiodothyronine decreased the uronic acid concentration in the submandibular glands. These changes occurred only in the hyaluronic acid and glycoprotein fractions. No changes in uronic acid concentration were detected in the retrolingual and parotid glands.     

Characteristics of the cellular cooperation in the connective tissue base of the gingiva in periodontitis

The features of clinical course of chronic generalized periodontitis were studied from the viewpoint of analysis of cellular cooperative connective tissue basis. This allowed to single out 2 groups of patients. In the 1st group, a potent lymphoid (seldom lymphoplasmocytic) infiltration was detected within the gingival connective tissue basis, and sIgA preserved or even increased in the mixed saliva. In the 2nd group, the oral cavity physiological neutralization of antigenic substances was impaired and neutrophilic leucocytes were dominating in the gingival connective tissue framework with considerably increased levels of serum IgG. The gingival tissue basophils population was investigated in these groups of patients and their variants given the histochemical characterization. Prognostic criteria of treatment effectiveness are derived from studies of biopsied gingival tissues.     

Masticatory function in children in the early periods of the development of the bite]

The authors suggest a test for accurate assessment of the masticatory function in subjects of various age groups. The results may be used as reference values in assessment of the function of the masticatory system in patients with various dental diseases.     

Site-specific variations in the concentrations of substances in the mouth

Estimates of the concentration of soluble substances in the oral fluids have generally been obtained by the analysis of whole saliva, either mixed in the mouth or obtained directly from the salivary duct. Such values may give little indication of concentrations at any particular site in the mouth. This is partly because substances do not always move easily about the mouth and also because there are large regional differences between the rates of oral clearance or retention of substances dissolved in saliva. Differential patterns therefore develop and are related, via the patterns of salivary flow, to the anatomy and physiology of the mouth. There are general features in these patterns common to all mouths and variations, which relate to characteristics of the individual, which may influence the rates of reactions occurring at different sites. The patterns may be associated with the site-specific patterns of dental disease, and they may have implications with regard to the best use of pharmaceutical agents. This paper describes some of the more recent data, problems and future possibilities in this hitherto unexplored area of oral physiology.     

钕铁硼永磁体磁在正畸领域应用展望

x钕铁硼永磁体是第三代稀土永磁，磁能积和矫顽力是目前永磁料中最高的，其优良的性能可使其成为固定正畸中理想的矫治力源。现就钕铁硼永磁体磁力正畸的优越性、磁体的性能以及镀氮化钛膜磁体的耐腐蚀性及生物相容性进行综述。