During the course of diagnostic and therapeutic services in oral healthcare settings, patient-care items come in contact with the patient’s skin, mucous membranes, sterile tissues, and body fluids. Failure to comply with evidence-based guidelines to properly sterilize or disinfect instruments and other patient-care devices carries the risk of healthcare-associated transmission of pathogenic organisms (e.g., HBV, HCV, and HIV).1-4

Sterilization is a validated process that destroys all forms of microbial life (Table 1). The term is intended to convey an absolute meaning, although the probability of the presence of pathogenic and other organisms can never be reduced to zero. Disinfection defines a process that is less lethal than sterilization, i.e., disinfection destroys some, but not all recognized pathogens and it does not predictably eliminate bacterial spores (Table 1).

Table 1. Sterilization vs. levels of disinfection by type of microorganism.2,3

Bacterial spores
(e.g., Bacillus species)
Mycobacteria (e.g., M. tuberculosis)Nonlipid or small viruses
(e.g., polio)
(e.g., Aspergillus Candida species)
Vegetative Bacteria (e.g., S. aureus)Lipid or medium-sized viruses
(e.g., HBV, HIV)
Sterilization processes+ ++ + ++
High-level disinfection+/- +++ ++
Intermediate-level disinfection- ++/- + ++
Low-level disinfection- -+/-+/- ++

In healthcare facilities, sterilization is carried out by physical and chemical methods. In oral healthcare settings, the primary sterilizing methods are steam under pressure and dry heat. For heat-sensitive patient-care instruments and other devices the principal agents used for sterilization or disinfection are germicides, i.e., chemical sterilants and high-level, intermediate-level, and low-level disinfectants (Table 1).

The term germicide refers to both disinfectants and antiseptics. Disinfectants are germicides that are applied to inanimate objects such as instruments and other devices and environmental surfaces. Antiseptics are germicides applied to skin and other living tissue (e.g., oral mucosa). Disinfectants are not intended for tissue antisepsis because they are toxic to skin and other tissues and antiseptics are not intended for disinfection of patient-care items.

With prolonged exposure times, chemical sterilants kill all forms of microbial life, including bacterial spores. At similar concentrations, but with shorter exposure times, the same chemicals are high-level disinfectants.They kill all pathogens but not all bacterial spores. Intermediate-level disinfectants kill mycobacteria, vegetative bacteria, most viruses and fungi, but they will not kill spores. Low-level disinfectants kill most vegetative bacteria and some viruses and fungi.

Visible soil (e.g., organic matter and salts) on instruments interferes with microbial inactivation during sterilization and disinfection processes. Cleaning isthe physical action of scrubbing patient-care items with water and a detergent or an enzymatic product and rinsing them with water to remove contaminants. Detergents are compounds with both hydophilic and lipophilic parts - the term “soap” is often used to refer to such products.