Gypsum is one of the most common natural minerals that is widely used in medical practice. To obtain the material, the crystals of the extracted gypsum stone are ground in special mills and burned in furnaces.
The composition of gypsum is a semi-aqueous calcium sulfate salt (CaSO 4 · H 2 O). Available in the form of a white powder.
Depending on the purpose of the gypsum, the grinding technology and the firing temperature will be different.
Classification
According to the requirements of the international hardness standard, the following types are distinguished:
- soft gypsum, used to make prints in orthopedic dentistry;
- ordinary (medical) plaster, used in general surgery and orthopedics;
- hard gypsum, intended for the manufacture of jaw models in dentistry;
- especially durable gypsum, used to create collapsible models of jaws;
- heavy-duty gypsum, designed for models in dental orthopedics that require ultra-high strength, is made with the addition of synthetic components.
When mixed with water after 5-7 minutes, the gypsum begins to harden, gaining strength. The material finds its final characteristics and hardness after complete drying.
The properties
Medical gypsum has gained its recognition due to its low price, affordability, ease of handling and such important properties for medical use as:
- non-toxicity, harmlessness;
- lack of smell;
- the ability to keep fit for a long time;
- resistance to interaction with water;
- low coefficient of shrinkage.
The powder has increased water absorption, when combined with water, it reacts with the formation of two-water gypsum and the transition of the mass to a solid state. The hardening speed is affected by gypsum calcination conditions, water temperature, gypsum-water mass ratio, and existing impurities. Water heated to 37 ° C accelerates the hydration reaction (particle binding), everything that is above and below this temperature slows down.
The water consumption per kilogram of powder is 0.6-0.7 liters. Duration of hardening - 10-15 minutes. You can evaluate the suitability of gypsum by holding it in your hands and squeezing it between your palms. If it crumbles during expansion, the material is dry and suitable for use. If a lump forms, then the gypsum is wet and you cannot work with it.
Application
Plain calcined gypsum is used to make gypsum dressings (bandages) for:
- anesthesia of fractures;
- imposition of glue traction;
- fixing damaged areas;
- manual reduction of bone fragments;
- reposition with the help of stretching sections.
Soft gypsum is used in the manufacture of both dental prints (full and partial), and prints from toothless jaws.
Removable dentures of the entire dentition or removable partial replacement dentures can be made of high-strength medical gypsum.
Terms of use
For favorable work with the material in dental practice, you should adhere to the following rules.
- Dental gypsum needs to be stored in a dry place. After each emptying, the tanks must be cleaned of residues.
- Tools used in the work should be washed and cleaned of traces of gypsum after previous use.
- The amount of gypsum kneading at one time should be designed for no more than three prints.
- Maintaining the proportions of gypsum and water when mixing is an extremely important factor.
Technology for producing gypsum for the manufacture of prints:
- powder is slowly poured into a container with water at a temperature of 20 ° C;
- wait for the complete subsidence of gypsum to the bottom;
- start mixing - the machine lasting no more than 30 seconds, manual - no more than a minute;
- the resulting mixture is poured into a mold.
For comfortable and quick work of doctors in surgery in the manufacture of plaster dressings, it is recommended to adhere to the following principles.
- To determine the amount of gypsum required, first measure the length of the dressing on a healthy limb.
- Applying plaster bandages is more convenient when the patient is in a supine position. For convenience, the diseased limb is raised above this level of position.
- Dressings made of medical plaster should be laid evenly, with a certain step, avoiding excesses, creases and folds.
- Areas experiencing heavy loads need to be strengthened and reinforced with an additional layer.
- The fingers and toes should be left open so that it is possible to track possible squeezing of the limb and remove the bandage on time.
- After applying the plaster bandages with stroking movements, they are brought closer to the actual contour of the limb surface, repeating all the bends and depressions.
- After drying, data on the date of application, the date of the fracture, a schematic image of the fracture and the estimated date of removal are applied to the dressing.
Removal of plaster casts
Petrified plaster bandages are removed using plaster forceps or scissors, a saw and a metal spatula. In the case when it is possible to cut gypsum, then use special scissors. If the space under the bandage does not allow, then a spatula is pushed under the bandages to protect the skin from injury. After that, cutting or sawing is carried out.
The bandage should be cut from the side where the soft tissues are. For example, plaster bandages to the middle third of the thigh are cut along the back surface, corsets - from the back, and so on. Cut edges spread apart and take out the limb. The removed parts of the dressing are discarded. Since the price of gypsum is low, its one-time use is very economical and low cost.
The presence of a doctor during the manipulation is mandatory: he controls the state of the limb and decides whether to apply a new plaster cast.
Where could I buy
Plaster medical is produced by companies manufacturing products for construction and finishing works. Its main difference from gypsum for construction purposes lies in the degree of grinding, and as a result, in faster curing times. You can buy gypsum for medical practice directly from the manufacturer. One of the leading manufacturing companies are Samaragips and Volma.
Medical plaster "Volma" is produced according to TU 5744-013-78667917-13, the product from "Samaragips" - according to TU 5744-013-21151476-2014 in paper bags weighing 20 or 25 kg. The cost of a kilogram varies from the type of gypsum and its purpose. On average, it is 15-25 rubles.