Chemical Hazards: Nitrous Oxide (N₂O)

Chemical Hazards

• Nitrous oxide (N₂O) is used as an anesthetic agent, but chronic exposure is associated with neurological abnormalities and reproductive derangements (infertility).
• Transient irritative reactions of the eyes and airways have been observed, mostly associated with exposure to volatiles from resin-based materials, X-ray chemicals, and cleansers.
• Prevention methods include:
  • System maintenance: inspecting and maintaining the anesthetic delivery system to prevent N₂O leakage.
  • Ventilation: using a scavenging system and room ventilation.
  • Work practices: selecting scavenging masks of proper sizes to fit patients, and monitoring the air concentration of N₂O.

Chemical Hazards

• Cyanoacrylate (CA) and its homologues have a variety of dental applications as adhesives and sealing agents.
• Reported toxicity of CA is uncommon in the dental workplace, but may manifest as conditions such as urticaria, contact dermatitis, and other dermatoses.
• CA can also lead to paresthesia in the fingers (usually the thumb, index, and middle fingers are affected).

Musculoskeletal Disorders

• The key to preventing work-related MSDs is Ergonomics, which is a science dealing with designing of a workplace.
• Ergonomics in dentistry means preventing musculoskeletal problems by enabling the dentist to adopt a more natural and comfortable posture, achieving patient-friendly treatment, improving treatment efficiency, and achieving treatment accuracy.
• Prevention methods include:
  • Adjusting the dental chair to a neutral position and keeping muscles relaxed.
  • Designing instruments with thicker, round, and hollow handles.

Noise Hazards

• The noise in dental clinics comes from suctions, saliva ejectors, turbines, engines, amalgamators, and compressors.
• Dentists are exposed to the noise of handpieces and ultrasonic scalers, at levels of 60-99 decibels, which can result in sensorineural hearing loss.
• Prevention methods include:
  • Wearing ear plugs or noise-cancelling headphones.
  • Considering the noise level of dental equipment when purchasing.
  • Monitoring hearing acuity on a regular basis.

Radiation Exposure

• Dentists are exposed to both ionizing and non-ionizing radiation in dental practice.
• Ionizing radiation has a shorter wavelength, higher frequency, and higher energy than non-ionizing radiation.
• The effects of low levels of exposure to ionizing radiation over periods of time may accumulate and could represent a potential hazard to health.
• Radiation effects are categorized as:
  • Somatic effects
  • Occupational effects

Occupational Hazards in Dentistry

• Definition of occupational hazard: a risk to a person usually arising out of employment.
• Types of occupational hazards include:
  • Biological health hazards
  • Physical hazards
  • Chemical hazards
  • Musculoskeletal disorders
  • Noise hazards
  • Radiation hazards
  • Psychological hazards
  • Legal hazards

Biological Health Hazards

• These hazards are constituted by infectious agents of human origin and include prions, viruses, bacteria, and fungi.
• A dentist can become infected either directly or indirectly through:
  • Cuts on the skin of the hand
  • Accidental bites by the patient
  • Needle wounds during anesthetic procedures
• Prevention methods include applying infection control protocols.

Physical Hazards

• Sources of physical injury include:
  • Debris from the oral cavity striking the eyes
  • Cuts from sharp instruments
  • Puncture wounds from needles or other sharp instruments
• Prevention methods include applying infection control protocols and preventing percutaneous exposure incidents (PEI).

Physical Hazards

• Percutaneous exposure incident (PEI) is a broad descriptive term that includes needlestick and sharp injuries, as well as cutaneous and mucous exposures to blood and serum.

Biological Health Hazards

• Indirect infection sources include aerosols of saliva, gingival fluid, and natural organic dust particles mixed with air and water, which can break free from dental instruments and devices.
• The main entry points of infection include epidermis of hands, oral epithelium, nasal epithelium, epithelium of upper airways, epithelium of bronchial tubes, epithelium of alveoli, and conjunctival epithelium.
• Prevention of biological health hazards involves applying infection control protocols.

Physical Hazards

• Sources of physical injury include debris from the oral cavity striking the eyes, cuts from sharp instruments, and puncture wounds from needles or other sharp instruments.
• Such injuries can result in the transmission of serious infectious diseases to the dental worker.
• Percutaneous exposure incidents (PEI) include needlestick and sharp injuries, as well as cutaneous and mucous exposures to blood and serum.
• The most common PEI is from needles and drilling instruments such as burs.
• PEI represents the most efficient method for transmitting blood-borne infections between patients and healthcare workers.

Needlestick Injuries

• Over 800,000 needlestick injuries occur each year in the United States despite continuing education and efforts to prevent them.
• Prevention of needlestick injuries involves ensuring the needle and surgical blade are sheathed when not in use, using a scoop technique, disposing of needles and sharp instruments in a sharp safe box, and taking care when cleaning away surgical sharps and wires, etc.
• Post-accidental management of needlestick injuries involves removing gloves, washing the site of injury under running water, avoiding scrubbing and encouraging bleeding, and then protecting and taking blood specimens of both the patient and the injured person for testing for HIV and Hepatitis.

Eye Injury

• Eye injury may occur from projectiles such as bits of calculus during scaling procedures and splatters from body fluids (bacterial and viral aerosols) while using high-speed hand pieces.
• Eye injury may also occur from intense dental curing light.

Occupational Hazards in Dentistry

• Definition of occupational hazard: a risk to a person usually arising out of employment that can also refer to a work, material, substance, process, or situation that predisposes, or itself causes accidents or disease, at a workplace.
• Types of occupational hazards include biological health hazards, physical hazards, noise hazards, radiation hazards, chemical hazards, musculoskeletal disorders, and psychological hazards.