Handling of Extracted Human Teeth: A Neglected Aspect

Sir, The extracted human teeth (EHT) are used for teaching and research purposes in dental undergraduate/postgraduate courses. These teeth are used to train the students for preclinical work, including ground sectioning, cavity preparation, and for endodontic procedures. EHT is also used for in vitro laboratory studies for the evaluation of bond strength, microleakage, and marginal adaptation of various materials and bonding agents.[1] Dental students are usually seen running to oral and maxillofacial surgery department or private dental clinics for the collection of EHT. It is necessary to clean, disinfect/sterilize, and store these teeth to remove biological tissues such as periradicular and periodontal tissues as they can be the potential source of infection. Dental students do not have adequate knowledge regarding storage, cleaning, disinfection, and sterilization protocol. Zucco et al. found that undergraduate students did not know about the activities adopted for the safe use of these teeth.[2] The processing of extracted teeth includes the use of personal protective equipment, especially gloves and mask, during all procedures such as cleaning, sterilization, and storage. The cleaning is done to reduce microbial count with the help of water and soap/enzymatic detergent with brush followed by cleaning in ultrasonic cleaner, because sterilizing/disinfecting agents do not act on dirty surfaces having the presence of organic or inorganic debris. The water used for cleaning should be potable, filtered, and deionized.[3] After cleaning caries and restorations should be removed. The calculus and other hard-tissue remnants should be removed with scalers. The teeth should be preferably inspected under magnification to detect the presence of any tissue remnants which can disturb the sterilization protocol.[3] For disinfection and sterilization Centers for Disease Control and Prevention and American Dental Association has recommended sterilization with steam under pressure as it does not affect the physical properties of dental tissues. Dominici et al. suggested autoclaving at 115°C for 40 min at 20 psi is the most effective method for the sterilization of EHT; however, autoclaving is not recommended for teeth-containing amalgam restorations as mercury vapors produced during this procedure can risk the health workers due to inhalation of this steam.[3,4] Kumar et al. demonstrated that 5.25% sodium hypochloride, 2% glutaraldehyde, quaternary ammonium compound saline solution, 3% hydrogen peroxide, and boiling for 20 min are not sufficient for the disinfection of EHT. Ten percent formalin can be used for the disinfection of EHT, but it is hazardous, potential carcinogen and irritates skin and eyes so washing EHT before use is recommended.[5] Moreover, few countries do not allow the use of chemical solutions for the sterilization of EHT due to environmental and occupational hazards.[1,3] The storage medium plays a significant role for maintaining chemical, physical, and mechanical properties of human teeth. Freezing is recommended as the best storage medium as it does not change the properties of dental tissues. Distilled water and thymol can also be used as they minimally effect bond strength.[3] Teeth containing amalgam restoration can be stored in 10% formalin. Kantoor et al. recommended if EHT has to be used for biological restoration eye solution is the best storage medium for 3–4 weeks.[6] The processing of EHT requires standard operating procedures to ensure occupational safety of students, health staff as well as to ensure proper maintenance of properties of dental tissues required for different purposes. Every dental institution must establish standard operating protocol for the sterilization and storage of EHT for teaching and research purposes. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.