Tooth Whitening Materials
Linda Greenwall in Tooth Whitening Techniques, 2017
As we have seen, whitening with peroxide reduces the bond strength of enamel by about 20% in the immediate effect. Studies by Torneck et al. (1991) have shown that there is a reduced bond strength of composite to enamel immediately after whitening with a 35% solution of hydrogen peroxide. However, the bond strength will improve if etching and bonding are delayed for 1–2 weeks postwhitening (Titley et al. 1991, Godwin et al. 1992). Waiting 2 weeks will also allow the color to stabilize. Hydrogen peroxide appears to change the surface chemistry. Resin tags in whitened enamel are less numerous, less defined, and shorter than those in unwhitened enamel (Titley et al. 1991). The residual oxygen in the whitened tooth surface also inhibits the polymerization of the composite resin (McGuckin et al. 1991) and disrupts the surface (Haywood 1999a).
Factors Controlling the Microflora of the Healthy Mouth
Michael J. Hill, Philip D. Marsh in Human Microbial Ecology, 2020
Dental restorations made of gold, silver amalgam, porcelain, or plastic materials accumulate dental plaque which is similar to that on natural teeth.32,119 The clinical adhesiveness of different materials becomes the same in spite of differences in basic surface chemical properties, because a film of salivary glycoproteins (acquired pellicle) covers any surface inserted in the mouth.120 The rate and quantity of plaque formation may, however, vary with the degree of surface roughness, and increased plaque formation has been demonstrated on aged composite resin fillings, which become more rough after 3 to 4 years in the mouth.121 A major clinical problem is plaque formation at imperfectly fitting margins of restorations.
The Dental Connection to Health
Aruna Bakhru in Nutrition and Integrative Medicine, 2018
Taking shortcuts while placing composite resin materials may save the dentist time but could hurt the patient. Regarding the idea that wearing out of composites might stress the biochemical system of the body may have merit. However, the symptoms that have been described (to a “T”) are that of myofascial pain dysfunction that results from the loss of what is known as posterior support. The composites wear out leaving a less than optimal structural platform for function to occur. When this happens, the muscles try harder and harder to work with the poorly balanced structures (teeth). The muscles then are in dysfunction and cause pain syndromes with the symptoms that have been described.
Ten-year follow-up on adoption of endodontic technology and clinical guidelines amongst Danish general dental practitioners
Published in Acta Odontologica Scandinavica, 2018
Merete Markvart, Helena Fransson, Lars Bjørndal
The combined response rate was lower in 2013 than the response rate in the 2003 questionnaire. The frequencies of GDPs reporting to use rubber dam often, increased from 4 to 29% and using apex locator often from 15 to 54% (p < .0001) when comparing the study groups of 2003 and 2013. A significantly higher proportion was also reporting use of rotary NiTi instruments; from 10% of the GDPs in 2003 to 69% in 2013 (p < .0001) (Table 1). Although the proportion of GDPs reporting use of stainless steel instrument was lower in 2013 than 2003, more than half (56%) of the responders still used stainless steel instruments (Table 1). There was also a significant decrease in the number of treatment visits for molar instrumentation. In 2013, only 6% of the GDPs used more than two appointments for instrumentation (p < .0001). Eighty-six percent of the dentists were in 2013 often using composite resin for coronal sealing compared to 81% in the 2003 group (p < .019), whereas the often use of indirect restorations had significantly decreased (p < .001).
Development of antibacterial composite resin containing chitosan/fluoride microparticles as pit and fissure sealant to prevent caries
Published in Journal of Oral Microbiology, 2022
Chun-Cheng Lai, Chun-Pin Lin, Yin-Lin Wang
C/F was prepared from chitosan/fluoride microparticles and a light-curable polymer matrix. This polymer matrix was prepared by mixing Bis-GMA, TEGDMA, EDMAB, and CQ in a weight ratio of 69:30:1:1 (Sigma-Aldrich, St. Louis, MO). The previously prepared silanized silica nanoparticles and C/F act as inorganic fillers, making up 20% of the composite resin. The polymer matrix was temporarily heated to 50°C, which enhanced the flowability and avoided trapped bubbles. Subsequently, the inorganic fillers were slowly added and stirred into matrix. The experimental composite resin was divided into three groups based on the composition of inorganic fillers: 1) 0% C/F and 20% silanized silica nanoparticles, abbreviated as 0% C/F; 2) 2% C/F and 18% silanized silica nanoparticles, abbreviated as 2% C/F; and 3) 4% C/F and 16% silanized silica nanoparticles, abbreviated as 4% C/F. ClinproTM fissure sealant (3 M ESPE, USA) was used as a control. Subsequent polymerization was carried out using an LED curing light with luminosity over 1,200 mw/cm2 and a wavelength of 460–510 nm (Motion LED-320D, Taipei, Taiwan).
The effects of heavy metals on human metabolism
Published in Toxicology Mechanisms and Methods, 2020
This article discusses the various hazards associated with heavy metal exposure on human metabolism. However, it is important to understand the methods by which the public come into contact with heavy metals, in order to avoid further contact. Based on previous research results, for many people regulatory limits have been exceeded and they are at the threshold of developing major organ toxicity. Governments must therefore take important steps to protect the population from this potential hazard to people’s health by advising people to avoid fish species that contain high levels of arsenic and mercury(Salnikow and Zhitkovich 2008). Therefore, contaminated water must be treated before it can be released into the environment to ensure that safe drinking water is available to the public. In terms of agricultural safety, arsenic-containing herbicides should be replaced by safer alternatives. Unlike Amalgam fillings, dental composite fillings should always be used. Removal of heavy metals from water can be done through ion exchange (Tariq et al. 2008), adsorption, membrane filtration and electrodialysis (Chen 2004). Therefore, we need to establish a defense mechanism to prevent exposure to heavy metals, which increases the content of reactive oxygen species (Ros) in the human body and eventually induces a series of oxidative damage processes. In future, more research is needed to ensure that human health is protected and is safe from the effects and hazards of heavy metals.
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