Comparison of elemental concentrations in the acinar cells of the human labial salivary gland.

Two types of acinar cells were observed in human labial glands by conventional and analytical electron microscopic and light microscopic techniques. The predominant type contained large and prominent secretory granules that were strongly mucicarmine and PAS (with and without diastase) positive. The second type contained small, lacy, secretory granules, and these cells were faintly positive with these stains. The elemental contents of the two types of granules were measured by analytical electron microscopy using digital mapping and spot analysis applied to freeze-dried cryosections prepared from gland slices incubated in vitro under non-stimulated conditions. The large secretory granules had significantly higher Ca, S and Mg concentrations and significantly lower Cl and K concentrations than the small granules. The difference in elemental contents probably reflects differences in the content of secretory macromolecules. Specifically, the S content is thought to reflect the anionic properties of the secretory macromolecules, while the levels of divalent cations are thought to be determined by electroneutrality requirements for macromolecular folding and storage. No differences were found in nuclear or cytoplasmic elemental concentrations between the two cell types.     

Dental status and treatment needs of a New Zealand institutionalised elderly population.

A survey of 359 elderly residents of rest homes and geriatric hospitals in the Manawatu and Horowhenua districts showed that approximately two-thirds were aged 80 or over, and 19.5 percent were dentate, with a mean 13.3 teeth per dentate subject. A mean of 4.6 teeth per dentate subject had caries of either the crown or root, or both. Older males had substantially higher extraction requirements than other subjects. The periodontal needs of the sample were generally low and dominated by the need for calculus removal.     

An SEM study of the effects of different irrigation sequences and ultrasonics

The root canals of 30 extracted human teeth with single canals were prepared biomechanically with hand instruments using a flaring technique. Three different irrigation regimes were used, with and without ultrasonic activation of a root canal file. The six irrigation sequences used in this study were as follows: Savlon, Savlon with ultrasound, EDTAC/NaOCl/EDTAC, EDTAC/NaOCl/EDTAC with ultrasound, NaOCl/EDTAC/NaOCl, and NaOCl/EDTAC/NaOCl with ultrasound. Scanning electron microscopic (SEM) examination of the prepared root canal walls showed a complete smear layer when Savlon was used. Ultrasound reduced the amount of smear with Savlon, but did not do so significantly with the other irrigation regimes. The most effective irrigation regime for removing smear layer and other debris was EDTAC/NaOCl/EDTAC. In all groups there was a significant decrease in cleaning efficiency as the apical end of the canal was approached.     

University of North Carolina Caries Risk Assessment Study. III. Multiple Factors in Caries Prevalence

The baseline caries experienced of approximately 5,000 children in South Carolina and Maine was used as the dependent variable in caries risk assessment analyses. Clinical, microbiologic, and demographic factors served as independent variables in a multivariate relationship to caries through regression and discriminant function analyses. Four factors--number of dental visits by the child in the past year, presence of white spot lesions, and both the urgency of need for restorative care and the future caries increment predicted by the examiner--associated significantly and consistently with caries prevalence in primary and permanent teeth of first and fifth graders at both study sites. Several factors associated significantly with caries prevalence at only one site or grade within a site, suggesting that wide applicability of a specific caries risk assessment model may be limited. In these analyses, sensitivity ranged from .60 to .72 and specificity varied from .86 to .91 in the four grade-site groups. The ultimate goal of this longitudinal study is to identify highly caries-prone children in time to prevent the occurrence of a future caries increment. Although the lack of consistent association of many variables, including microbiologic factors, with baseline caries prevalence was unexpected, it is expected that some of these variables will contribute predictive power in the prospective study.     

A Critique of Topical Fluoride Methods (Dentifrices, Mouthrinses, Operator-, and Self-applied Gels) in an Era of Decreased Caries and Increased Fluorosis Prevalence

Within the last 20 years there has been a decrease in the caries prevalence of US schoolchildren, a change in the intraoral caries pattern, and a slowing of the progress of lesions. Simultaneously, the prevalence of enamel milder, cosmetically acceptable forms and is more noticeable in fluoride-deficient communities than those with optimal or above-optimal water fluoride concentrations. Circumstantial evidence indicates that a principal contributor to the caries decline is the extensive use of fluoride dentifrices. Conversely, although use of a fluoride dentifrice can add to the total daily amount of ingested fluoride in preschool children, there is little evidence to suggest that dentifrice ingestion is a principal factor causing the fluorosis increase. The value of fluoride methods may be assessed in relative or absolute terms. The relative, or percentage, caries reduction attributed to fluoride mouthrinses and gels appears to be a property intrinsic to the methods themselves and generally is little affected by the caries activity of the population being treated. Conversely, the absolute, or numerical, caries reduction is dependent upon the level of disease in the population. Thus, the reported caries decline reduces the number of surfaces prevented from developing caries, even though the percentage reduction remains substantially unchanged. Although inadvertent ingestion of fluoride can result from the use of mouthrinses and gels, there is little evidence to suggest that they have contributed to the fluorosis increase. When using topical methods, prudence should prevail to avoid ingestion of fluoride. Fluoride dentifrices should continue to be used routinely, and although lower potency dentifrices may be considered, the literature does not provide strong support for their need. Use of fluoride mouthrinses and gels for individual patients should be predicted upon their caries activity or risk. Use of these methods in public health programs is a matter of cost-effectiveness, which will be influenced by the caries prevalence of the target population.     

The accuracy of polyvinyl siloxane impressions made with standard and reinforced stock trays

A laboratory investigation was done to assess the influence of proprietary stock trays on the accuracy of impressions recorded with heavy light-body (HL) and putty light-body (PL) wash impression techniques. Two brands of trays were tested and the same trays were reinforced with acrylic resin. Individual die accuracy and overall distortion of the resultant casts were assessed. PL impressions in both stock trays gave undersized buccolingual dimensions at the preparation finishing lines whereas reinforcing the trays reduced this distortion. Significant inaccuracy at the second molar was found for all trays when PL impressions were made. These distortions would have resulted in clinically unacceptable dies. HL impressions, regardless of tray type, produced highly accurate dies at this critical site. Resultant overall cast distortion was reduced, but not eliminated, by using reinforced trays with either PL or HL techniques.     

Bilateral mesiodentes of identical twins--a case report

A pair of identical 10-year-old Chinese twins with bilateral mesiodentes of opposite orientation are presented. Three mesiodentes were conical and impacted, while the other one had erupted and was incisiform in shape. All roots of the mesiodentes were completely formed. Intrapair twin comparison showed a high degree of genetically determined concordance, with minor differences subject to environmental influences. The prevalence of mesiodens and rate of monozygotic twins in various ethnic groups are reviewed. Mirror image traits and verification of monozygocity in identical twins are also discussed.     

Quantitative study of velopharyngeal function post-palatoplasty]

The computer of nasopharyngeal fiberscope(NPF) for quantitative analysis was carried out to assess the palate articulation of 43 subjects,and normal articulation of 60 subjects.The rest,/a/,/s/and /m/ articulation of NPF pictures were calculated for veloparyngreal function via computer.     

The up-regulation of heme oxygenase-1 expression in human gingival fibroblasts stimulated with nicotine

BACKGROUND: Cigarette smoking is a major risk factor in the development and further progression of periodontal diseases. Heme oxygenase-1 (HO-1) is known as a stress-inducible protein and functions as an antioxidant enzyme. There is limited information on the expression of HO-1 in smoking-associated periodontal disease. OBJECTIVES: The aim of the present study was to investigate the effects of nicotine on the expression of HO-1 protein in cultured human gingival fibroblasts in vitro and further to compare HO-1 expression in gingival tissues obtained from cigarette smokers and non-smokers in vivo. METHODS: Western blot assay was used to investigate the effects on human gingival fibroblasts exposed to nicotine. In addition, antioxidants catalase, superoxide dismutase (SOD), and N-acetyl-l-cysteine (NAC) were added to test how they modulated the effects on nicotine-induced HO-1 expression. Gingival biopsies taken from the flap surgery of 20 male patients with periodontal disease (10 cigarette smokers and 10 non-smokers) were examined by immunohistochemistry. RESULTS: The exposure of quiescent human gingival fibroblasts to 10 mm nicotine resulted in the induction of HO-1 protein expression in a time-dependent manner (p < 0.05). The addition of glutathione (GSH) precursor NAC inhibited the nicotine-induced HO-1 protein expression (p < 0.05). However, SOD and catalase did not decrease the nicotine-induced HO-1 protein expression (p > 0.05). The results from immunohistochemistry demonstrated that HO-1 expression was significantly higher in cigarette smokers (p < 0.05). HO-1 was noted in the basal layers of epithelium, inflammatory cells, and fibroblasts in specimens from cigarette smoking. CONCLUSIONS: Taken together, these results suggest that HO-1 expression is significantly up-regulated in gingival tissues from cigarette smokers, and nicotine may, among other constituents, be responsible for the enhanced HO-1 expression in vivo. The regulation of HO-1 expression induced by nicotine is critically dependent on the intracellular GSH concentration.     

A field trial on semi-annual fluoride varnish applications among the special needs schoolchildren

This study assessed cariostatic effect of one fluoride varnish Duraphat among children with a low caries risk and compared this effect to group of a moderate caries risk, belonging to same ethnic group with same socioeconomic background. Results of this study showed that fluoride varnish had cariostatic effect in a group of children with a moderate caries risk but not among those with a low caries risk.