Effect of Bleaching on Mercury Release from Amalgam Fillings and Antioxidant Enzyme Activities: A Pilot Study

Purification and characterization of L-arginine deiminase from Penicillium chrysogenum

L-arginine deiminase (ADI, EC 3.5.3.6) hydrolyzes arginine to ammonia and citrulline which is a natural supplement in health care. ADI was purified from Penicillium chrysogenum using 85% ammonium sulfate, DEAE-cellulose and Sephadex G200. ADI was purified 17.2-fold and 4.6% yield with a specific activity of 50 Umg- 1 protein. The molecular weight was 49 kDa. ADI expressed maximum activity at 40oC and an optimum pH of 6.0. ADI thermostability was investigated and the values of both t0.5 and D were determined. Kd increased by temperature and the Z value was 38oC. ATP, ADP and AMP activated ADI up to 0.6 mM. Cysteine and dithiothreitol activated ADI up to 60 µmol whereas the activation by thioglycolate and reduced glutathione (GSH) prolonged to 80 µmol. EDTA, α,α-dipyridyl, and o-phenanthroline inactivated ADI indicating that ADI is a metalloenzyme. N-ethylmaleimide (NEM), N-bromosuccinimide (NBS), butanedione (BD), dansyl chloride (DC), diethylpyrocarbonate (DEPC) and N-acetyl-imidazole (NAI) inhibited ADI activity indicating the necessity of sulfhydryl, tryptophanyl, arginyl, lysyl, histidyl and tyrosyl groups, respectively for ADI catalysis. The obtained results show that ADI from P. chrysogenum could be a potential candidate for industrial and biotechnological applications.

Assessment of Biochemical Parameters of the Oral Fluid before and after Using Office Teeth Whitening Systems

One of the most important functions of the oral fluid is to maintain oral homeostasis. In-office teeth whitening systems are able to change the mineral metabolism and the activity of a number of enzymes in the oral fluid, but there are conflicting data in publications about this. The aim of this study was to compare the effect of Opalescense Boost, ZOOM Advance POWER, and ZOOM Phillips White Speed, which contain different percentages of hydrogen peroxide, on the performance of oral fluid. After the procedure of whitening teeth with the studied in-office systems, the concentration of calcium in the oral fluid increased, and the activity of alkaline phosphatase decreased. Calcium levels returned to baseline values after 30 days, and alkaline phosphatase activity returned after 14 days. There was no significant difference in the changes in calcium concentration and alkaline phosphatase activity between different tooth whitening systems. Chemical teeth whitening with the Opalescense Boost system caused the largest change in the activity of superoxide dismutase in the oral fluid compared to the ZOOM Advance POWER and ZOOM Phillips White Speed photocatalytic teeth whitening systems. An increase in the activity of superoxide dismutase by +75.5% was shown immediately after the procedure of teeth whitening with the Opalescense Boost system, which indicated an increase in the power of antioxidant defense mechanisms. To assess the effectiveness and safety of using various whitening systems, it is possible to study the dynamics of the activity of superoxide dismutase, which reflects the processes of antioxidant protection of the oral cavity.

Mercury exposure, neopterin profile, and tryptophan degradation in dental technicians

Amalgam has been widely used as a restorative dental material for over 150 years. Most standard dental amalgam formulations contain approximately 50% elemental mercury in a mixture of copper, tin, silver, and zinc. Mercury is a highly volatile metal, which can easily vaporize to a colorless and odorless gas. It has been demonstrated that mercury is released from dental amalgam, which is increased by chewing, eating, brushing, and drinking hot liquids. Besides this, amalgam is the main occupational exposure source of mercury for dental workers. It is known that mercury exposure causes immune modulation in humans. In this study, it was aimed to evaluate the changes in neopterin levels and tryptophan (Trp) degradation in dental technicians. It was observed that low levels of occupational mercury exposure resulted in decreased neopterin, kynurenine (Kyn), and Kyn/Trp levels. Moreover, mercury and neopterin levels had a significant positive correlation in workers. The lower neopterin levels and Kyn/Trp in dental technicians compared to an unexposed group indicates a possible immune suppression with low level of occupational mercury exposure during amalgam preparation. The relationship between urinary mercury levels as an indicator of occupational mercury exposure and neopterin reminded an effect on T-cell-mediated immune response.

Immunotoxicity of mercury: Pathological and toxicological effects

Mercury (Hg) is toxic and hazardous metal that causes natural disasters in the earth's crust. Exposure to Hg occurs via various routes; like oral (fish), inhalation, dental amalgams, and skin from cosmetics. In this review, we have discussed the sources of Hg and its potential for causing toxicity in humans. In addition, we also review its bio-chemical cycling in the environment; its systemic, immunotoxic, genotoxic/carcinogenic, and teratogenic health effects; and the dietary influences; as well as the important considerations in risk assessment and management of Hg poisoning have been discussed in detail. Many harmful outcomes have been reported, which will provide more awareness.