Infection safety during dental visits
The dental profession is associated with a high risk of infection. During invasive procedures, cross-transmission of infection between the patient and the physician is possible. Adhering to asepsis rules protects against dangerous diseases: viral hepatitis (B, C), HIV infection, syphilis, tuberculosis, tetanus, and anthrax.
Infection can enter a wound in two ways:
- Exogenous (about 90% of cases) — from the air, via non-sterile instruments, equipment, or suture material.
- Endogenous — from the patient's own internal foci (skin, oral cavity, ENT organs). The activation of microflora depends on the state of the immune system.
Preparation of the physician's hands and the operating field
The hands of a dental surgeon must be free of cracks and hangnails, and nails must be cut short.
There are two main approaches to hand antisepsis:
- Classical method: washing hands and forearms with a sterile brush and soap, rinsing, drying with a sterile wipe strictly from fingertips to elbows, then wiping with an alcohol swab.
- Accelerated methods: application of a 20% chlorhexidine solution, cerigel, ethyl alcohol (96%), or ND-410 solution.
Before a surgical intervention, the patient's face is treated with alcohol, and the oral cavity is treated with a 0.12% chlorhexidine solution. The operating field itself is isolated with sterile drapes.
Pre-sterilization cleaning (PSC)
Before sterilization, all instruments undergo mandatory cleaning to remove protein, fat deposits, and drug residues. Multi-part reusable items are disassembled.
PSC algorithm:
- Disinfection (soaking): for 60 minutes in a 3% chloramine solution, 6% hydrogen peroxide, or a 5–8% alaminol solution.
- Rinsing: under running water (15 seconds).
- Washing phase: immersion in Biolot solution warmed to 40 °C for 15 minutes.
- Mechanical cleaning: processing each instrument with a brush or swab directly in the washing solution (15 seconds per item).
- Final rinsing: with running tap water (1 minute per item), then with distilled water (30 seconds).
- Drying in open air.
The quality of cleaning is checked on 1% of items from a batch (but not less than 3 pieces). To detect occult blood, the azopiram or amidopyrine test is used — a positive reaction produces a blue-purple coloration.
Sterilization methods in dentistry
Sterilization guarantees the complete destruction of all microorganisms, including their spores. Thermal methods are most commonly used in dentistry.
| Method | Agent | Mode | Features |
|---|---|---|---|
| Dry-heat sterilization | Hot air | 180 °C — 1 hour | Ecological, instruments can be sterilized in kraft paper pouches. Not suitable for all materials. |
| Autoclaving | Pressurized steam | 134 °C (4 min) or 120 °C (12 min) | Fast penetrating method. Cutting instruments may become blunt due to moisture. |
| Glass bead sterilization | Heated glass beads | 240–270 °C (a few seconds) | Only for the working part of small endodontic instruments. |
In addition to thermal exposure, the following methods are used:
- Gas sterilization (ethylene oxide): provides 100% reliability and allows instruments to be sterilized in packaging, but the gas is highly toxic.
- Plasma sterilization: exposure to argon plasma ("ball lightning" effect) at 60–80 °C for 10–12 minutes. Destroys bacterial proteins.
- Chemical (liquid) sterilization: soaking in chloramine or hydrogen peroxide solutions. Requires significant time (from 10 hours) and thorough rinsing, acts only superficially.
Quality control of sterilization
To verify the effectiveness of sterilizers, three types of control are used:
- Chemical (thermal): ampoules containing substances with a specific melting point (benzoic acid, resorcinol, antipyrine) are placed inside the packaging. If the substance has melted, the required temperature was reached.
- Bacteriological: culturing washings from instruments and rooms on nutrient media. The absence of microorganism growth confirms sterility.
- Biological indicators: using test strips containing spores of resistant microorganisms. If microbes survive after the sterilization cycle, the entire batch of instruments is rejected.
Briefly: answers to topical questions
What types of test cultures (microorganisms) are used in biological indicators for sterilization control?
Thermophilic spore-forming bacilli and spore-bearing non-pathogenic cultures are used for biological sterilization control.
- Stearothermophilus bacillus (Bacillus stearothermophilus) — a thermophilic spore-forming bacillus.
- Lichenformis bacillus (Bacillus licheniformis) — a thermophilic spore-forming bacillus.
Spores of these microorganisms are placed inside the items being sterilized or placed in drums (bix) as test tubes. The absence of their growth and their destruction indicate the effectiveness of the chosen sterilization regime.
What chemical preparations are used for cold liquid sterilization of dental instruments?
Solutions of chemical substances are used for cold liquid sterilization:
- Hydrogen peroxide — 3–6% solution.
- Chloramine — 1–3% solution.
- Hypochlorous acid salts.
- Alcoholic chlorhexidine solution.
- Pervomur.
- Formaldehyde for special equipment.
The solutions are used for soaking and processing instruments; after sterilization, the object must be rinsed free of the sterilizing solution.
Which antiseptics are used to treat the patient's oral mucosa before a surgical intervention?
Before a surgical intervention, the patient's oral mucosa is treated with antiseptics:
- Chlorhexidine — 0.12% solution or its derivatives; a 0.05% solution is also indicated before tooth extraction.
- Potassium permanganate — 0.1% solution.
- Eludril — 0.04% solution.
- Corsodyl — 0.2% solution immediately before anesthetic injection.
During tooth extraction, antiseptic treatment with 0.1% potassium permanganate solution, 0.12% chlorhexidine, or 0.04% Eludril aims to eliminate up to 90% of pathogenic microflora and prevent socket infection.
Sources of endogenous infection are easy to remember using the ENT acronym: Larynx (throat/larynx), Otos (ear), Rhinos (nose).
Class and exam questions
How are dental handpieces sterilized?
A specific method involves boiling in liquid petrolatum with a 2% oxyquinoline solution (for 1 hour) followed by centrifugation. Chemical cleaning is also used: wiping with alcohol/chloramine followed by the use of disinfection systems such as «Terminator» or «Assistina».
What is the difference between the amidopyrine and azopiram tests?
Both tests aim to detect blood residues after pre-sterilization cleaning. They differ only in their chemical reagents, but the result is the same: in the presence of blood, the indicator turns blue-violet.
How long can sterile instruments be stored on the doctor's table?
An open sterile table set up by a nurse for patient appointments remains sterile for no more than 6 hours. An alternative is storing instruments in individual kraft pouches or germicidal chambers (e.g., "Microcid-Med").
What else to study on this topic
- Specifics of sterilizing dressings and suture materials in sterilizing drums (bixes)
- Specifics of disinfecting orthopedic impressions, mouthguards, and dental splints
- Dentist protocol in case of HIV exposure risk
- Pathogens and incubation periods of infections transmitted during dental visits
- Ergonomics basics: how to properly organize a dentist's workspace
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Other topics in "Chapter 2. Organization of Dental Practice"
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