Potential risk factors their management strategies in prosthodontic practice

Physical Threats

Physical threats connected with prosthodontic practice include direct physical trauma, fire and burns, acoustic trauma, eye damage and various problems associated with bad working posture.

According to a study, Prosthetics dentists have the second highest preponderance rate of 4.5% yearly for the percutaneous injuries. ^[3] Usual factors include use of high speed of rotary instruments which creates the projectiles at 39 m/second which are very heated, abrupt and infected.^[4] Blue curing light used for polymerization of restorative resin material range from 400-500 nm wavelength which is additionally related to corneal damage and abrasion.^[5] The effect of blue light are often cumulative or acute depending upon its nature and duration of use. Vulnerability to blue light usually results in acute injuries. Consistent with report, there's increase ocular injury risk at 440nm of wavelength.^[5][6][7]

Dentist had always been an occupational interest within the subject of Noise Induced deafness (NIHL). They emit sound measuring from 66 db to 91 db.^[8] The primary conclusive evidence that damage to hearing may result from exposure to the present noise was published by Taylor and associates in 1965 during carefully controlled study of dentists.^[9] It’s also been estimated that most turbine users are exposed to high speed hand pieces. It’s estimated that sound energy contribution of a typical practice is about 8% of dentists. ^[9] However, risk depends upon the susceptibility of a specific individual, total daily exposure and sort of instruments used.

Chemical Hazards

Various synthetic and natural occurring chemicals has been utilized in both clinical prosthodontic practice also as within the laboratory. These materials include alloys, resin polymers, dental cements, ceramics, waxes, eugenol containing materials, sodium hypochlorite, elastomeric impression materials etc. ^[10][11][12] Many materials are known to cause dermatitis and have harmful effects when ingested or inhaled. They can have local, systemic, immediate or delayed effect. These materials enters inside the body through direct skin absorption, ingestion and inhalation and cause of release of components and various degradation products which causes inflammation, immunological reactions and even carcinogenesis over their prolonged exposure.^[11]

Polymethyl methacrylate resin contain chemicals like butyl methacrylate, di-butyl phthalate and cadmium salt based colouring agents. Methyl methacrylate vapour in surrounding air at the extent of 125 ppm or above may cause teary eyes, pharyngitis and coughing. MMA can easily penetrate clothing and even surgical gloves. Maximum permissible limit for the quantity of mehyl methacrylate is 410 mg/m³. ^[12][13]

Metal alloys pose hazards to dentist and technicians during casting and finishing of the metal restoration and frameworks. A study reported that 53 out of 70 dental technicians suffering from pneumoconiosis which might be thanks to dust from processing of those dental materials.^[14][15]

NOISH recommend exposure limit to those particles as limit of 0.05 mg/m³. Inhalation of these particles may lead to silicosis.

Roberta et al tested polyethers and vinyl polysiloxanes for cytotoxicity and showed polyethers to be more cytotoxic than vinylsiloxanes. ^[16][17]

Biological Hazards

Biological hazards are constituted by various infectious agents like virus, bacteria and fungi and can be both transimissable and non transmissible diseases. Transmissible diseases of greatest concern to any kind of health care provider are HIV, HBV and tubercle bacillus.^[18]

A clinician are often infected by a cut or a wound, needle stick injury, aerosols containing saliva, blood and gingival fluid. Aerosol spray and contaminated impressions are common source of infection in Prosthodontic practice. Other possible sources of infectious contamination are dental unit waterlines, hand pieces, saliva ejectors, suction tubes, airotors, hand pieces and radiological instruments. ^[19] Dental unit waterlines may harbor opportunistic and respiratory pathogens like Legionella species, mycobacterium species and Pseudomonas species. The dimensions of particles of the aerosols produced is of great concern because it ranges between 2 to 30 μm which can directly reach the alveoli and cause respiratory ailments.

The common path for entry of infection includes skin of hands and face; oral, nasal and conjunctival epithelium and epithelium of airway tract including trachea, bronchus and alveoli. Impressions often travel out of the clinical setup to the laboratories and extends the horizon of the infection.^[20] It act as a vehicle for the transfer of both pathogenic bacteria and virus and cause cross contamination within the clinic and the laboratory. Dental cast poured from such impressions act as a major source of infection in dental laboratory. Plaster dust from handling of such dental casts gets into the respiratory tracts and settles over the garments for a substantial long period of time.^[21]

A thorough knowledge of infections, mode of transmission and various safety measures is vital to beat the spread of infection. Protection are often achieved by the mixture of immunization procedures, use of varied barrier techniques and strict adherence to the infection control guidelines. Rubber dam should be used whenever possible as it will eliminate all contamination arising from blood and saliva. All the members of dental team should be vaccinated for hepatitis B and hepatitis C. Impressions should be disinfected in the suitable medium (2% gluteraldehyde and iodoform solution etc) before sending to the laboratory. Gloves should be worn while pouring the impressions. Protective coverings in the form of uniforms such as gowns and aprons, gloves, glasses, masks or face shield should be worn by the clinician as well as by the assistant while performing various clinical procedures. Sharp instruments and needles should be handled carefully. In the case of skin puncture by a contaminated instrument should be encouraged to bleed and washed thoroughly under the running water.

All instruments should be thoroughly cleaned before sterilization. High volume aspirators or suction devices are used to reduce any risk of cross infection from aerosols. The risk can be further reduced by good ventilation.

Waste disposal should be considered seriously to prevent the spread of infection. Needles and sharp waste should be placed in the puncture proof containers and securely sealed. Medical waste must be disposed off in red bags and non infective waste should be disposed off via thick black bags.

Ergonomic Hazards

Ergonomic hazards generally comprises of physical factors that harms the musculoskeletal system. Musculoskeletal disorders are common health issue among the dental professionals. Musculoskeletal Disorders or MSDs are injuries and disorders that affect the human body’s movement or musculoskeletal system (i.e. muscles, tendons, ligaments, nerves, discs, blood vessels, etc). ^[22] Common symptoms of MSD’s includes discomfort, disability or persistent pain in joints, muscles, tendons and other soft tissues. Common MSD’s include Carpal Tunnel syndrome, tendonitis, muscle or tendon strain, tension neck syndrome, epicondylitis, degenerative disc disease etc. risk factors comprise repeated movements and prolonged awkward or forced body postures.^[22][23]

Prosthdontists are at high risk of neck and back problems. Limited work area and impaired vision in the oral cavity frequently causes the clinicians to assume stressful body postures for long periods of time which in turn leads to lower back pain, stiffness in hands and shoulders, muscle weakness, presence of paresthesia or tingling sensations.

Back pain syndrome diagnosed in dental clinicians occurs due to spine degeneration in its different phases. Due to constant monotonous movements and mechanical vibration there is always some sort of stress on wrist and elbow joint.^[24]

This can be minimized by at least 6 minute of rest from work every hour, proper ergonomic dental unit design, personalized rehabilitation exercises, regular stretching and aerobic activities.

Psychosocial Hazards

Dentists perceive dentistry being more stressful than other professions. Important risk factors increasing stress among dentists are coping with difficult or uncooperative patients, over workload, constant drive for technical perfection, underuse of skills, challenging environment and low self esteem.^[25][26] One of the consequence of chronic occupational stress is professional burnout. It is defined as a syndrome of emotional exhaustion, depersonalization and reduced personal accomplishment that occur among professionals. Burnout can be best described as gradual physical, emotional and mental erosion of the person. It may lead to panic disorder or generalized anxiety disorders. In prosthodontics, elderly patients are difficult to manage and satisfy with the treatment.

It can be managed by attending stress management workshops, doing deep breathing exercises, relaxation, hypnosis and desensitization techniques.