Release of mercury from dental amalgam and its influence on salivary antioxidant activity.

Dental amalgam fillings are known to release significant amounts of mercury (Hg) in saliva which could represent a continuous source of oxidative damage to mouth tissues. The present investigation was aimed at verifying this hypothesis by determining a possible correlation between salivary Hg levels and salivary total antioxidant activity (TAA), which is used as an index of oxidative stress. Samples of saliva from 34 healthy donors were analyzed for Hg content, by vapor atomic absorption spectrometry, and for TAA, by determining the ferric reducing ability ('FRAP' method). A significant correlation between Hg and the number of amalgam restorations or total amalgam surface was evident in both the male and female subjects. A significant negative correlation between TAA and Hg levels or number of amalgam restorations or amalgam surface was evident in females, indicating that small increases in salivary Hg were sufficient to produce a decrease in salivary TAA. On the other hand, no significant correlation was found in the males. The present study provides, for the first time, evidence of a pro-oxidant role of the amalgam Hg chronically released in saliva.

Cytoskeletal and membrane bound antigens in human oral normal and malignant keratinocytes: an intensity of staining analysis.

In this study, we tested the hypothesis that a significant difference exists in the integrated optical density (IOD) of membrane and cytoplasmic antigens in monolayer keratinocytes cultures. Oral normal and two malignant (SCC15 and SCC25) keratinocyte cultures were stained with antibodies specific for E-cadherin, beta-catenin, beta-1 integrin, cytokeratin (CK) 14, CK19, CK10/11 and involucrin. The IOD recorded (n = 12) was analyzed for significant differences using a two-way analysis of variance (significance level set at alpha = 0.05); antibodies and cell cultures were grouped according to Tukey's Group Comparison post-test. The majority of normal cell cultures exhibited E-cadherin, beta-catenin, involucrin and beta-1 integrin IOD values significantly higher than the two SCC cell lines. No definite staining pattern distinguished normal and malignant cells in relation to cytokeratins 14, 19 and 10/11. Our observations suggest that IOD measures constitute a good predictor of antigen steady state levels in monolayer cell cultures. According to these observations, SCC cell lines and normal cells appear to differ in the expression of E-cadherin, beta-catenin, beta-1 integrin and involucrin, although some variability within normal cells can also be observed.

[Biocompatibility and physico-mechanical properties of the new Venezia root canal sealer. In vivo and in vitro test according international standards]. / Biocompatibilità e caratteristiche meccanico-fisiche del nuovo cemento endodontico Venezia. Prove in vivo e in vitro secondo norme ISO.

At the moment, in most countries, there are laws in force which impose to the manufacturers well regulated testing in order to investigate and guarantee an acceptable biocompatibility of medical devices before their commercialization. Many international laboratories are committed to the definition of investigation methodologies and to the evaluation of biocompatibility in order to obtain research standards, capable to provide reproducible and comparable objective quantitative data. In every country, technical committees were put together for a standardization of methodological procedures, followed by European and international technical boards which proposed and codified methodologies and investigation approaches. UNI-EN-ISO laws contain all the results and constitute a reference point for any consideration on or evaluation of the biocompatibility of a medical device. Based on these laws, we evaluated the biocompatibility and determined the physical-mechanical characteristics of the new Venezia (Cabon S.p.A.) endodontic ZOE sealer. The Subcutaneous Implant Technique according Safavi et al. (in vivo test, ISO 10993: 1-6 Biological evaluation of medical and dental materials and devices) and Autian test of Emolysis on Rabbit Erythrocytes (in vitro test) allowed us to evaluate a good biocompatibility of the new product. Furthermore, its Setting and Working time, its radiopacity, Solubility and its Flow value completely satisfy the requirements of international standards (ISO/DIS 6876 Dental root Canal Sealing Materials). We can finally deduce that Venezia fulfil the ideal functional properties of an endodontic cements.

Influence of amalgam fillings on Hg levels and total antioxidant activity in plasma of healthy donors.

In order to evaluate the influence of mercury (Hg) levels on antioxidant power in human plasma, 26 healthy people were evaluated by a dentist and their plasma analyzed for Hg content by atomic absorption and total antioxidant activity (TAA) by FRAP method. Hg plasma concentration correlated with number of amalgam restorations, suggesting that Hg released from fillings is a source of Hg in non-occupational exposed people. Fish consumption, in fact, showed no influence on Hg plasma levels, perhaps because Italian subjects examined in the present group used low quantity of fish at week or kinds of fish with light contamination. TAA negatively correlated with Hg plasma revealing a pro-oxidant role of Hg released from amalgam fillings.

Salivary mercury levels in healthy donors with and without amalgam fillings.

Dental amalgam (AMG) is the most diffused dental filling material. Since it is constituted for at least 40-45% of Hg, many questions have raised about its safe use. Hg particles from dental amalgam dissolve in saliva and, being ingested, they reach the blood stream through the intestinal mucosa. It has been demonstrated that amalgam fillings continuously release Hg vapour and that there is detectable Hg in expired and inspired air of amalgam owners. It is not yet fully accepted that AMG fillings represent the principal source of Hg for man and the aim of this study was to evaluate if the mercury level in saliva: 1) was higher within people bearing dental amalgam restorations than in people with no restorations; 2) was different between males or females; 3) increased in relation to the surface of amalgam restorations. The results showed a correlation between number of fillings and salivary Hg, between amalgam surface and salivary Hg. The Authors could finally assert that AMG fillings represented the principal source of salivary Hg in the subjects studied.

Release of mercury from dental amalgam and its influence on salivary antioxidant activity.

Dental amalgam fillings are known to release significant levels of mercury (Hg) in saliva which could represent a continuous source of oxidative damage to tissues. The present investigation was aimed at verifying this hypothesis by determining a possible correlation between salivary Hg levels and salivary total antioxidant activity (TAA), used as an index of oxidative stress. Samples of saliva from 34 healthy donors were analyzed for Hg content, through vapor atomic absorption spectrometry, and for TAA, by determining the ferric reducing ability ('FRAP' method). A significant correlation between Hg and the number of amalgam restorations or total amalgam surface was evident in both the male and female subjects. A significant negative correlation between TAA and Hg levels or number of amalgam restorations or amalgam surface was evident in females, indicating that small increases in salivary Hg were sufficient to produce a decrease in salivary TAA. On the other hand, no significant correlation was found in the males. The present study provides, for the first time, evidence of a pro-oxidant role of the amalgam Hg chronically released in saliva.

Morpho-structural variations of bacterial spores after treatment in steam vacuum assisted autoclave.

This study intended to verify, through microbiological techniques and TEM investigations, the killing of bacterial spores after treatment in steam autoclave, and to propose strictly morphological considerations about the target of this sterilisation process. Autoclave is the most common device for sterilising instruments in order to prevent cross infections in dental offices. The autoclave efficiency has been improved in the last years and part of this improvement is related to both a better and more correct use of the autoclave system and to the technological innovations introduced in the last generation of devices. However, associations as ADA or CDC suggest to regularly verify the process of 'autoclaving' through biological indicators (BI). The most commonly used BI are made of spores strips or suspensions of Bacillus Subtilis (pb 168) and Bacillus Stearothermophilus (ATCC 10149). They visually prove, changing colours on enzymatic base, the death of micro-organism and if the physical parameters, necessary for sterilisation, have been achieved. These two strains of endospore-forming bacteria were processed and prepared following two different techniques: Karnovsky fixed and epon embedded--phosphotungstic acid fixed for direct observation. The kind and the extent of analysed modifications are extremely various: from deep lacerations, which changed the spore structure, to little clefts which let the cytoplasm go out.