[Corrosion of titanium in presence of dental amalgams and fluorides]. / La corrosione del titanio in presenza di amalgami e fluoruri.

AIM: The aim of this study was to evaluate the behaviour of titanium (Ti) in precipitant condition, and more precisely the resistance against corrosion of Ti in presence of fluorides and the electrochemical interaction between Ti- amalgam couples in fluorinated solution. METHODS: The experimental test was made with the use of an electrochemical cell. The following materials were tested: commercially pure Ti and 2 types of amalgams, the Persistalloy (Prs) and the IQC. Palladium (IQC.P). The free corrosion potential of Ti and the amalgams, the polarization curves of both amalgams and the corrosion current of the Ti-amalgam couples in the measurements were performed in 3 different electrolytic solutions: Ringer solution, fluorinated neutral Ringer solution and acid fluorinated solution. The three corrosive media are described. RESULTS: The results showed that Ti could be damaged by the presence of fluorides with an acid pH: Ti potential becomes more negative in acid fluorinated solution. The corrosion currents between Ti and amalgam couples were considered: the amalgams underwent anodic oxidation in neutral Ringer, but a reversal phenomenon occurred in the fluorinated acid solution: Ti was damaged and the amalgams both Prs and IQC.P became the cathodic partner of the couple. In neutral fluorinated solution the IQC.P amalgam induced a significantly higher corrosion of Ti, when compared to the Prs one. CONCLUSION: Results clearly show the dependence of the Ti corrosion behaviour on the pH and composition of the solution and that the outcome of the damage is affected by the composition of other metals.

Dental anomalies associated with genetic factors.

The article reviews the association between dental anomalies and genetic diseases. Knowledge of these hereditary diseases will enable the dentist to make a more extensive analysis of the families in which such diseases occur, and above all to evaluate more precisely the dental aspects that such conditions favour. This will lead to better management of diseases linked to malocclusion, congenital absence of teeth and anomalous development of dental tissues. Hereditary diseases are caused either by a single mutant gene, inherited from 1 parent and acting as dominant gene, or from a pair of mutant genes, inherited from both parents and acting recessively. Autosomal-dominant and autosomal-recessive inherited diseases are described, together with hereditary sex-linked conditions and those of multi-factorial origin. The purpose is to review such diseases so that the dentist can make an early diagnosis in clinical practice, check the predisposition toward such diseases and put in place preventive measures.

Immunohistochemical study of carcinoembryonic antigen (CEA) in gastric tumors: correlation with preoperative serum levels, histologic type, and grade of anaplasia of the tumor.

The occurrence of carcinoembryonic antigen (CEA) was studied in 45 cases of gastric tumors by the immunoperoxidase technique. CEA-positive staining was found in 48.8% of tumors. A correlation was found between preoperative CEA values and tumor CEA staining. All patients with serum CEA values below 2.5 ng/ml showed CEA-negative staining of tumor. In patients with serum CEA values between 2.6 and 10 ng/ml, the tumors showed a minority of CEA-positive cells; but in patients with serum CEA values above 10 ng/ml, the tumors contained a majority of CEA-positive cells. CEA-positive staining was found in 34.4% of tumors of the diffuse type, and in 75% of tumors of the intestinal type. A high percentage of CEA positivity was seen in well-differentiated tumors (87.7%) compared to the moderately differentiated (69.2%), and to the undifferentiated (28.7%). A faint CEA-positivity was observed in intestinal metaplasia, while normal gastric mucosa was CEA-negative.