Infection control and space preparation
A critical aspect of safe practice is infection control. All surfaces of equipment and furniture touched by the dentist or their assistant during treatment must be reliably protected with special disposable barrier covers.
To ensure process efficiency, all preparation is carried out strictly before the appointment begins:
- Instruments and dental materials are pre-arranged on sterile trays.
- The contents of the trays strictly correspond to the stages of the upcoming procedure.
- There should be nothing superfluous in the workspace—only items necessary for the specific clinical case.
Clock-face concept and zone distribution
The space around the patient's head is conventionally divided into sectors like a clock face. This helps standardize workflows:
- Dentist's zone: located from 8:00 to 12:00.
- Assistant's zone: occupies positions from 2:00 to 4:00 (sometimes extending to 5:00).
- Static zone (12:00–2:00): a multifunctional sector where usually no one is positioned. Exceptions include "six-handed" procedures, such as simultaneous work with multiple lasers or complex restoration systems.
- Transfer zone (5:00–8:00): the space where the assistant safely passes instruments to the attending dentist.
Ergonomics and workspaces
Rational instrument placement directly affects attention focus (which is always directed at the oral cavity) and the dentist's health. Two types of spaces are distinguished:
- Small workspace. Located at a distance of up to 25 cm from the body. This is the most favorable zone: the dentist can pick up frequently used instruments by touch without looking away from the patient or stretching their arm.
- Large workspace. Located at a distance of about 50 cm. Considered unfavorable for frequent use, as it requires full arm extension and loss of visual control over the operating field.
Proper posture and biomechanics of the dentist
To prevent occupational musculoskeletal disorders, the dentist must maintain strict biomechanical posture parameters.
Basic angles and positions:
- The angle of the thigh relative to the floor should be 25–30°, with the knees positioned below the level of the pelvis.
- The hip flexion angle is 90–110°, which helps maintain the natural curves of the spine.
- Obtuse angles should be formed in anatomical regions (under the knee, at the hip joint, between the ankle and foot, as well as between the upper arm and forearm).
- The optimal working distance (from eyes to the patient's face) is 40–50 cm.
The dentist's elbows should be kept as close to the torso as possible, and forearms should be at the level of the patient's head. Any turns toward the patient are performed with a synchronized movement of the head and shoulders to avoid overloading the cervical spine.
Working with an assistant ("four-handed dentistry")
In paired work, the assistant occupies the 3:00 or 9:00 position. When working while seated, the assistant's chair is adjusted to be 10–15 cm higher than the dentist's chair—this ensures a full view of the operating field.
The assistant's back and neck should be straight, thighs parallel to the floor, and feet resting on a special footrest. The tips of the evacuation systems (saliva ejector and high-volume evacuator) are placed on the side toward which the patient's head is tilted, without obstructing the dentist's view. The mobile cart is positioned to the assistant's right hand.
Briefly: answers to topical questions
What stages does the sterilization of dental handpieces include?
The sterilization of dental handpieces includes disinfection, pre-sterilization cleaning, lubrication, and direct sterilization.
- Disinfection, cleaning, and lubrication — carried out in specialized devices (e.g., Assistina or express processing in a Terminator device within 3 seconds).
- Sterilization — performed by boiling in vaseline oil followed by centrifugation, or with steam at 140 °C (for surgical handpieces).
What impression disinfection methods are used in dentistry?
Chemical solutions and plasma disinfection are used for disinfecting impressions in dentistry.
- Preliminary cleaning — rinsing items in running water for 1 minute.
- Chemical disinfection — treatment with a 0.5% chlorhexidine solution, MD-520, 0.1% desoxon, or a 6% hydrogen peroxide solution.
- Plasma disinfection — is also used.
- Post-processing — rinsing impressions under running water after exposure to the disinfectant.
Class and exam questions
How is infection control organized for work surfaces?
All equipment surfaces touched by personnel during treatment must be covered with special disposable barriers.
What is the essence of the clock-face concept?
This is a system for dividing the workspace around the patient's head. The dentist works in the 8:00–12:00 zone, the assistant in the 2:00–4:00 zone, and instruments are transferred in the 5:00–8:00 sector.
Which workspace is considered optimal for instruments?
A small workspace located at a distance of up to 25 cm from the body. It allows picking up instruments by touch without looking away from the oral cavity.
At what height should the assistant sit?
The assistant's seating level should be 10–15 cm higher than the dentist's level to ensure good visual control of the operating field.
What else to study on this topic
- Peculiarities of the dentist working in the "9, 10, 11, and 12 o'clock" positions
- Rules for positioning the patient's head when treating various tooth groups
- Technique for stabilizing the dentist's hands using support points
- Specifics of "six-handed" work and the use of the static zone
- Principles of medical deontology during a dental appointment
Master the entire topic in the «Propaedeutics of Dentistry» course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Sterilization and Disinfection in Dentistry" and 868 more pages of the subject
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Other topics in "Chapter 2. Organization of Dental Practice"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.