[EXOTHERMIC REACTIONS OF PLASTER IMMOBILIZATION ­ ANALYSIS OF THREE KINDS OF PLASTER BANDAGES].

Exothermic reaction of plaster is a very important characteristic to understand, especially when it comes to complications which can occur during local temperature change during molding plaster of Paris. And these complications directly influence the speed and quality of treatment. In this paper we measured temperatures of plaster bandage tiles 10×10 cm, from three different manufacturers in Croatian hospitals: Safix plus (Hartmann, Germany), Cellona (Lohmann &Rauscher, Austria) and Gipsan ( Ivo Lola Ribar, Croatia). We made three different plaster tiles 10×10 cm, from 10, 15 and 30 layers of plaster bandages. We immersed plaster tiles in two different water temperatures, one group in water 22 °C, and another in 34 °C. Although all plaster bandages have similar chemical characteristics, we have measured some differences. All three kinds of plaster bandages used in Croatia have low exothermic reaction when plaster molding is done in standard conditions, average local temperature is low and there is no danger of local burns. We immersed a plaster tile with 15 layers in water on 34° C, and highest average temperature was measured at Gipsan (46.2 °C), then Cellona (41.3 °C) and Safix plus (38.9 °C). On the same water immersion temperature, on plaster tile with 30 layers average temperatures were Gipsan (48.4°C), Cellona (45.4 °C), and lowest in Safix plus (41.3 °C). Plaster tiles form all manufacturers, when used 15-30 layers thick, and water immersion temperature is 34°C, develop average temperature over 40°C, in duration from 8-12 minutes. Between three different plaster bandages analyzed, Gipsan (Ivo Lola Ribar, Croatia) developed highest temperature, and some plaster tiles were measured over 50 °C.

[PHYSICAL PROPERTIES OF PLASTER BANDAGES]. / FIZIKALNA SVOJSTVA SADRENIH ZAVOJA.

The physical properties of plaster bandages are a very important factor in achieving the basic functions of immobilization (maintaining bone fragments in the best possible position), which directly affects the speed and quality of fracture healing. This paper compares the differences between the physical properties of plaster bandages (mass, specific weight, drying rate, elasticity and strength) and records the differences in plaster modeling of fast bonding 10 cm wide plaster bandages, from three different manufacturers: Safix plus (Hartmann, Germany), Cellona (Lohman Rauscher, Austria) and Gipsan (Ivo Lola Ribar ltd., Croatia). Plaster tiles from ten layers of plaster, dimension 10 x 10 cm were made. The total number of tiles from each manufacturer was 48. The water temperature of 22 °C was used for the first 24 tiles and 34 'C was used for the remainder. The average specific weight of the original packaging was: Cellona (0.52 g/cm3), Gipsan (0.50 g/cm3), Safix plus (0.38 g/cm3). Three days after plaster tile modeling an average specific weight of the tiles was: Gipsan (1.15 g/cm3), Safix plus (1.00 g/cm3), Cellona (1.10 g/cm3). The average humidity of 50% for Safix plus and Cellona plaster tiles was recorded 18 hours after modeling, while for the Gipsan plaster tiles, this humidity value was seen after 48 hours. On the third day after plaster modeling the average humidity of the plaster tiles was 30% for Gipsan, 24% for Safix and 16% for Cellona. Cellona plaster tiles made with 34 °C water achieved the highest elasticity (11.75±3.18 MPa), and Gipsan plaster tiles made with 22 °C had the lowest (7.21±0.9 MPa). Cellona plaster tiles made with 34 °C water showed maximum material strength (4390±838 MPa), and Gipsan plaster tiles made with 22 °C water showed the lowest material strength (771±367 MPa). The rigidity and strength of Cellona and Gipsan plaster are higher in tiles made in warmer water, and for Safix plus are higher in tiles made in cooler water. All three types of plaster differentiate in physical properties. The differences in mass and specific weight before and after plaster modeling are minimal. There are greater differences in drying rate, elasticity and strength between the three different plaster materials.