Anti-caries effect of a 2% Na2PO3F-dentifrice in a Danish fluoride area

Abstract A 3-year experimental toothbrushing study was conducted in a natural fluoride area in Denmark to evaluate the anti-caries effect of a 2 % sodium monofluorophosphate dentifrice. In a previous report the results for the total population of 1,407 schoolchildren, representing a broad age-span (7–12 years), at the commencement of the study in 1970 were given. In the present report results are presented for two subpopulations of “8-year-olds” and “11-year-olds” at the commencement of the study. Differential analysis of the effect of the, test dentifrice on defined types of surfaces for the two subpopulations is given. The evaluation was performed using both the conventional DMF-indices and the recently published ECSI-Index⁶. The evaluation showed that the test dentifrice had a valuable anti-caries effect in both age groups, above and beyond the effect of the waterborne fluoride. Proximal surfaces were affected most baneficially by the active agent both in relative and absolute terms. However, an appreciable caries-preventive effect was also found on the “pit and fissure” surfaces.     

Application of MRI movie for observation of articulatory movement during a fricative /s/ and a plosive /t/: Tooth visualization in MRI

Objective:To use an accurate method of tooth visualization in magnetic resonance imaging (MRI) movie for the observation of spatio-temporal relationships among articulators.Materials and Methods:The subjects were two volunteers. Each subject repeated a vowel-consonant-vowel syllable (ie, /asa/; /ata/), and the run was measured using a gradient echo sequence. A custom-made clear retainer filled with the jelly form of ferric ammonium citrate was then fit onto the dental arch, and a T1-weighted turbo-spin-echo sequence was taken. Landmarks were used for superimposition of the incisor boundary onto sequential images of MRI movie. Tracings were conducted to observe the spatio-temporal relationships among articulators.Results:The incisor boundary was clearly visible in the magnetic resonance images. After superimposition, the contact distance of the tongue to palate/incisor was found to be longer during /t/-articulation than during /s/-articulation. There were prominent differences in images with and without tooth superimposition in the front oral cavity.Conclusions:The method could distinctly extract a tooth boundary in MRI. Detailed configurational relationships between the tongue and tooth were observed during the production of a fricative and a plosive in MRI movie using this method.     

EIS study of the FeIII/FeII redox couple at a Nafion®-coated Pt electrode

The redox reaction Fe^III + e ? Fe^II is studied at a Nafion^®-filmed Pt electrode using both steady-state and EIS methods. It is shown that the fitting of the EIS experimental data can be greatly improved by using the new concept of a ‘theoretical–experimental hybrid model’, i.e., by introducing experimental data obtained at a bare electrode in the theoretical model for a filmed electrode. It is also shown that a combined steady-state and EIS study cannot lead to a separate determination of the three key parameters of the system: the diffusion coefficient in the polymer film (D_f), the thickness of the film (L), and the partition coefficient between the solution and the polymer (γ), only the two parameters γD_f/L and L²/D_f being obtained from experimental data by a curve fitting procedure. Finally, an exhaustive theoretical EIS study in quiescent solution is also proposed.     

The oral/dental/craniofacial complex as a model for inflammatory disease

Many inflammatory diseases, including periodontitis, are the result of uncontrolled destruction of host tissues by the host's own inflammatory response. Periodontitis as well as other inflammatory diseases are initiated by bacteria that results from host cell-mediated tissue destruction. The study of inflammation of the oral cavity and craniofacial complex provides an excellent window to the understanding of more complex and difficult to study conditions. In this article, the inflammatory process in periodontitis is reviewed with an emphasis on control pathways that naturally limit inflammation.     

Remineralization and demineralization in situ from a triclosan/co-polymer/fluoride dentifrice

An in situ study was conducted to evaluate the effect of a dentifrice containing 1100 ppm F (NaF) and triclosan, an anti-plaque agent, on remineralization of artificially-formed caries lesions in thin sections of human enamel. The thin sections were placed in mandibular partial dentures of 15 subjects and covered with a steel mesh to provide an area for plaque accumulation. The subjects brushed their teeth and dentures three times daily for two-week periods in a cross-over design, after which the specimens were removed and analyzed by quantitative microradiography for changes in mineral content. Results showed that lesions treated with the triclosan-fluoride product were remineralized 18.0 +/- 23.4% compared with 19.0 +/- 32.3% from a 1100-ppm F (NaF) positive control. Use of a placebo dentifrice resulted in 71.9% demineralization. The findings showed that triclosan neither enhanced nor interfered with the promotion of remineralization by fluoride.     

Salvaging a porcelain/metal bridge with a bonded porcelain-fused-to-metal overcasting

Porcelain fractures from ceramo-metal fixed bridges often are troublesome for both dentist and patient, especially when problems occur in the anterior region. Repairing these fractures can be a challenge because the repair must be not only durable but also pleasing esthetically. While repair can be achieved with a composite resin material, matching the color and texture with the surrounding intact porcelain often is difficult and the bonding between the resin and porcelain is susceptible to marginal leakage, which may result in esthetic failure. This article reviews a technique designed to salvage a fractured porcelain-fused-to-metal bridge and return it to form and function by utilizing a porcelain-fused-to-metal overcasting.     

The clinical comparison of a triclosan/copolymer/fluoride dentifrice vs a breath-freshening dentifrice in reducing breath odor overnight: a crossover study

Objective: The objective of this randomized, crossover study was to compare the effectiveness of the triclosan/copolymer/sodium fluoride (TCF‐AF) dentifrice and a commercially available breath‐freshening dentifrice containing fluoride for their ability to reduce volatile sulfur compounds (VSC) associated with oral malodor overnight. Methods: Following a 1‐week washout period of brushing with a regular fluoride dentifrice, subjects reported to the clinical site without performing oral hygiene, eating or drinking in preparation for baseline breath sampling. Subjects were randomly assigned a test dentifrice and instructed to brush their teeth for 1 min, twice a day for 1 week. On the morning of day 8, subjects returned to the test site, having refrained from oral hygiene, eating and drinking, for overnight sampling. Following a second 1‐week washout period, subjects repeated the same regimen, but now using the other test product. At each measurement, the level of breath VSC was evaluated using a gas chromatograph equipped with a flame photometric detector. Measurements were taken in duplicate, and then averaged. The levels of VSC were expressed as parts per billion (ppb) in mouth air. Results: At baseline, the mean breath VSC levels for the TCF‐AF and breath‐freshening dentifrice were 618 and 581 ppb respectively. There was no statistically significant difference between the baseline levels. Overnight, the TCF‐AF and the breath‐freshening dentifrice reduced breath mean VSC levels to 267 and 521 ppb respectively. This gave a 56.7 and 10.2% reduction in VSC levels for these two products, respectively, compared with baseline. The reduction for the TCF‐AF dentifrice was significantly different (P < 0.05%) from that of the breath‐freshening dentifrice. Conclusion: The results of this randomized, double‐blind, crossover study indicate that the TCF‐AF dentifrice was significantly more effective than a commercially available breath‐freshening dentifrice containing fluoride in reducing breath VSC associated with bad breath overnight.     

Compatibility of machined Ce-TZP/Al2O3 nanocomposite and a veneering ceramic

OBJECTIVES: Due to its high fracture toughness ceria-stabilized ZrO(2)/Al(2)O(3) nanocomposite (Ce-TZP/A) could be superior to Y-TZP in clinical use. However, the compatibility to veneering ceramics is not yet investigated and therefore subject of this study. METHODS: Fracture strength and crazing resistance of veneered Ce-TZP/A frameworks (Nanozir, Matsushita Electric Works) were investigated in comparison to sintered and hipped Y-TZP (Hint-ELs). Frameworks were machined (HiCut, Hint-ELs), sintered where applicable (hiTherm, Hint-ELs), and veneered in a standardized procedure (Cerabien ZR, Noritake). Fracture strength of the crowns was assessed in a shear test (n=10). Biaxial flexural strength of the core materials was measured according to ISO 6872 (n=10). To assess the thermal compatibility between framework and veneer the coefficient of thermal expansion (CTE) of all materials was determined (n=3) and a crazing test carried out (n=12). RESULTS: Fracture strength was equal for crowns with Ce-TZP/A (866.6+/-132.1N) and sintered Y-TZP (904.5+/-168.2N), while crowns with hipped Y-TZP were significantly stronger (1380.6+/-253.2N) (Student's t-test, p<0.05). These values correlated with the biaxial flexural strength of the three core materials (Ce-TZP/A: 1238.0+/-200.0MPa, sintered Y-TZP: 1181.8+/-232.5MPa and hipped Y-TZP: 1521.8+/-163.8MPa). Failure of both hipped and sintered Y-TZP crowns occurred by chipping of the veneer or total fracture, while the Ce-TZP/A crowns predominantly failed by chipping of the veneer. In the crazing test both sintered and hipped Y-TZP performed slightly better than Ce-TZP/A. CTE's were as follows: Ce-TZP/A: 10.3microm/mK, sintered Y-TZP: 10.7microm/mK, hipped Y-TZP: 10.9microm/mK, and Cerabien ZR: 9.9microm/mK. SIGNIFICANCE: The CTE of the veneering ceramic has to be adjusted to Ce-TZP/A frameworks.     

Experiments with a toothpaste containing polydimethylsiloxan/triclosan

Polydimethylsiloxan (silicone oil) adsorbs to solid surfaces and to teeth because of its low surface tension, forming a thin, resistant layer. Triclosan is a lipidsoluble, antibacterial substance which is added to toothpastes and mouthwashes to inhibit plaque. Triclosan can be dissolved in silicone oil, conferring an antibacterial property on the layer of silicone oil which forms on solid surfaces. The aim of the present study was to determine whether a toothpaste containing triclosan/silicone oil has any effect on established gingivitis in a test panel of 33 teenagers. This toothpaste and a placebo paste were randomly distributed to the panel, and the number of gingival bleeding points was recorded. No instruction in oral hygiene was given. The panel was then examined 4 wk later and the number of bleeding points again recorded. It was found that the reduction in bleeding points was significantly higher in the group which had used the triclosan/silicone oil paste than in the placebo group. Deposition of a lipid-soluble, antibacterial agent in a layer of silicone oil which adsorbs to the tooth surfaces because of its physical properties represents a new and promising principle in preventive dentistry.     

Dentist/patient communication: a review.

Good communication between dentists and their patients benefits the patient, the dentist and the dental team. In this paper a model is described to help our understanding of the processes of communication between dentist and patient. This model, together with evidence from empirical research, is used to advise general dental practitioners on how to improve their communication skills.