Determining the vertical dimension of occlusion requires 5.5 mm subtraction from the position of the mandible in pronunciation of the word "OLO" or 7.5 mm in pronunciation of the word "ELE".

Disorders of mineral metabolism are very important for osteoporosis. This disorder may involve entire skeleton, especially stomatoghnatic complex. Therefore osteoporosis is one of very important illnesses in dentistry, especially in prosthodontics, because of the supporting nature of bone tissue for all types of dental prostheses.

Tooth loss leads to a variety of disorders of the orofacial system function, it changes the appearance of the patient and also disrupts patient's social life. The aim of this study was to analyze the prevalence of partial and complete tooth loss among prosthetically managed patients in the reference institutions in the three towns of southern Serbia, during the period from 2002 to 2011. According to medical records, statistical analysis of the prevalence of both complete and partial edentulism was done based on mobile and fixed prosthetic dentures made in three different dental institutions approved by the Ministry of Health of Serbia (Niš, Vranje, Leskovac). The study sample consisted of patients' dental records. Taking into account the limitations of this study, a decrease in loss of teeth in the age structure of 20 to 40 years among prosthetically managed patients could be observed. Edentulism was significantly higher in patients over the age of 60 years and more prevalent in female patients. In the Healthcare Center Vranje, there was a significant increase in teeth loss among prosthetically managed patients, with a rate of 2.4% per year. The number of edentulous patients older than 60 years of age is not in keeping with the trend in Europe, and can be explained by low economic standard, wars waged in the Balkans in the 90's in the past century, migration from rural to urban areas and the newly introduced legal provisions.

In conclusion it is pointed out that the preparation of irreversible hydrocolloides must be carried out by strictly obeying the powder-water weight ratios. The sections of the models obtained by irreversible hydrocolloides of various consistencies, that is by applying different pressures, point to minimal displacement of tissues and great differences in the retention force in favour of the compressive impression.

No statistically significant difference was found in the width of the neutral zone, between the group of patients with prominent alveolar ridges (the control group), and that with the flat ones. There was, also, no difference at all, at any level of the vertical dimension of occlusion, that could possibly bear statistical significance.