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5/31/2018 » 6/3/2018
2018 OSAP Annual Conference

FAQ - Miscellaneous - 2016
FAQ - Miscellaneous - 2016



Should gloves be worn when Dental models are handled, trimmed etc. in the laboratory. If so, what kind of gloves are best practice?

Regardless of the dental setting, appropriate Personal Protective Equipment (PPE) must be worn and all manufacturer directions should be followed concerning infection control and safety practices. If you are unable to locate the operator’s manual for the model trimmer or other equipment in the dental lab, you should contact the manufacturer/distributor for a replacement copy. The manufacturer can advise you regarding the use of PPE including gloves (and what type) for their specific model trimmer product. 

In general, the 2003 CDC guidelines for infection control in dentistry states as follows:

Dental prostheses or impressions brought into the laboratory can be contaminated with bacteria, viruses, and fungi(411,412). Dental prostheses, impressions, orthodontic appliances, and other prosthodontic materials (e.g., occlusal rims, temporary prostheses, bite registrations, or extracted teeth) should be thoroughly cleaned (i.e., blood and bioburden removed), disinfected with an EPA-registered hospital disinfectant with a tuberculocidal claim, and thoroughly rinsed before being  handled in the in-office laboratory or sent to anoff-site laboratory (2,244,249,407). The best time to clean and disinfect impressions, prostheses, or appliances is as soon as possible after removal from the patient’s mouth before drying of blood or other bioburden can occur. Specific guidance regarding cleaning and disinfecting techniques for various materials is available (260,413–416). DHCP are advised to consult with manufacturers regarding the stability of specific materials during disinfection.

In the laboratory, a separate receiving and disinfecting area should be established to reduce contamination in the production area. Bringing untreated items into the laboratory increases chances for cross infection (260). If no communication has been received regarding prior cleaning and disinfection of a material, the dental laboratory staff should perform cleaning and disinfection procedures before handling. If during manipulation of a material or appliance a previously undetected area of blood or bioburden becomes apparent, cleaning and disinfection procedures should be repeated. Transfer of oral microorganisms into and onto impressions has been documented (417–419). Movement of these organisms onto dental casts has also been demonstrated (420). Certain microbes have been demonstrated to remain viable within gypsum cast materials for <7 days (421). Incorrect handling of contaminated impressions, prostheses, or appliances, therefore, offers an opportunity for transmission of microorganisms (260). Whether in the office or laboratory, PPE should be worn until disinfection is completed (1,2,7,10,13).

If laboratory items (e.g., burs, polishing points, rag wheels, or laboratory knives) are used on contaminated or potentially contaminated appliances, prostheses, or other material, they should be heat-sterilized, disinfected between patients, or discarded (i.e., disposable items should be used) (260,407). Heat-tolerant items used in the mouth (e.g., metal impression tray or face bow fork) should be heat-sterilized before being used on another patient (2,407). Items that do not normally contact the patient, prosthetic device, or appliance but frequently become contaminated and cannot withstand heat-sterilization (e.g., articulators, case pans, or lathes) should be cleaned and disinfected between patients and according to the manufacturer’s instructions. Pressure pots and water baths are particularly susceptible to contamination with microorganisms and should be cleaned and disinfected between patients (422). In the majority of instances, these items can be cleaned and disinfected with an EPA registered hospital disinfectant. Environmental surfaces should be barrier-protected or cleaned and disinfected in the same manner as in the dental treatment area.

Unless waste generated in the dental laboratory (e.g., disposable trays or impression materials) falls under the category of regulated medical waste, it can be discarded with general waste. Personnel should dispose of sharp items (e.g., burs, disposable blades, and orthodontic wires) in puncture-resistant containers.1

Infection Control and Management of Hazardous Materials for the Dental Team states:

Protective Barriers

All items coming from the oral cavity must be sterilized or disinfected before being worked on in the laboratory and before being returned to the patients. Asepsis procedures vary for each type of dental material. General recommendations for procedures and materials can be made. Laboratory infection control also involves, depending on need, the wearing of personal protective barriers such as gloves, safety eyewear, gowns, and masks. One must wear barriers when handling contaminated items until they have been decontaminated.

A successful laboratory infection control program requires meeting two major criteria: (1) the use of proper methods and materials for handling and decontaminating soiled items and (2) the establishment of a coordinated infection control program between dental offices and laboratories. This program will help dental practitioners and dental technologists create and maintain mutually effective infection control programs.

Receiving Areas

The dental team should create a receiving area to handle all items sent to the laboratory or handled in the laboratory areas within the dental practice. This area needs running water and handwashing facilities. To cover the area and the counter surfaces with impervious paper and to clean and disinfect the area regularly is the best practice. The amount of cleaning and disinfection depends on the rate of use of the area. No item (impression or prosthesis) should enter the receiving area until it has been disinfected properly.

One should use personal protective equipment when handling items received in the laboratory unit until they have been disinfected. Such equipment includes gloves and some type of gown. Protective eyewear may be needed to prevent contact with splashes.2


Grinding, Polishing, and Blasting

As stated before, perform laboratory work on previously disinfected impressions, appliances, and prostheses. Bringing untreated materials into the laboratory establishes the potential for cross-contamination.

Operation of a dental lathe provides an opportunity for the spread of infection and for injury. The rotary action of the wheels, stones, and bands generates aerosols, spatter, and projectiles. Whenever one is using the lathe, one should wear protective eyewear, properly place the front Plexiglas shield, and ensure that the ventilation system is operating properly. The use of a mask is highly recommended. The air-suction motor should be capable of producing an air velocity of at least 200 ft/min. Maximum containment of aerosols and spatter can be achieved when a metal enclosure with hand holes is fixed to the front of the hood of the lathe. One can sterilize or disinfect all attachments, such as stones, rag wheels, and bands, between uses or throw them away. The lathe unit must be disinfected twice a day.

One should use fresh pumice and pan liners for each case (Figure 16-3). The modest cost of the materials and the proven significant microbial contamination in reused pumice prohibits repeated use.

Polishing of appliances and prostheses before delivery is a necessary activity. Polishing exposes the operator to potential cross-contamination and physical injury. However, if the item being polished has been prepared aseptically, the risks of infection are reduced to a minimum. To avoid the potential spread of microorganisms, one should obtain all polishing agents (e.g., rouge) in small quantities from larger reservoirs. One should never return unused material to the central stock but should throw it away. Most polishing attachments (e.g., brushes, wheels, and cups) are single-use, disposable items. One should sterilize reusable items between uses, if possible, or at least disinfect the items.

One should follow the manufacturer’s instructions for cleaning and sterilizing or disinfecting items that become contaminated but that normally do not contact the patient (e.g., burs, stones, polishing points, rag wheels, articulators, case pans, and lathes). If the manufacturer’s instructions are not available, one should clean and heat sterilize heat-tolerant items or clean and disinfect, depending upon the degree of contamination.2

The authors of Practical Infection Control In Dentistry further state:

A National Institute of Occupational Safety and Health (NIOSH) approved dust/mist face mask and eye protection must be worn when operating lathes, model trimmers, or other rotary equipment. Safety shields and ventilation systems are also required when using mounted rotary equipment, such as lathes, to reduce the risk of aerosols, spatter, and projectiles. 3


PPE must be used when handling contaminated items in the laboratory.  Depending on the amount of contamination or the task being performed, PPE (e.g., gloves, masks, protective eyewear, and gowns) is indicated. In the dental laboratory following disinfection or sterilization to decontaminate an item, most items can then be handled as noninfectious if separate “clean” work areas are available. 3

Following decontamination of laboratory items, some type of gown or laboratory coat is still recommended in the work area to protect the employee’s clothes, and other barriers are often required as a safety precaution. 3


If gloves are worn during the operation of a lathe, extreme caution must be taken to avoid injury resulting from the glove being caught in the lathe. The risk of infection when handling contaminated items is considered greater than the physical hazard; therefore, gloves should be worn when necessary and appropriate caution exercised. 3

In summary, appropriate PPE must be used when handling contaminated items in the dental laboratory. Gloves should be worn when handling a contaminated object. If the item has been fully decontaminated, then it can be handled without gloves. Appropriate hand hygiene should occur after handling. As stated above, if gloves are worn during the operation of a lathe, extreme caution must be used to avoid injury. Further questions regarding disinfection products and procedures as well as the operation and use of the model trimmer should be directed to the product manufacturers. The manufacturer can advise you regarding the use of PPE including gloves (and what type) for their specific model trimmer product. 


1.      Kohn WG, Collins AS, Cleveland JL, Harte JA, Eklund KJ, Malvitz DM, Centers for Disease Control and Prevention (CDC). Guidelines for infection control in dental health-care settings—2003. MMWR Recomm Rep 2003;52(RR-17):1-61.    Accessed on January 18, 2016.

2.      Miller CH. Infection Control and Management of Hazardous Materials for the Dental Team, 5th edition. Elsevier/Mosby Publishers. Pages 185-188.

3.      Molinari JA and Harte JA. Practical Infection Control In Dentistry – Third Edition. Wolters Kluwer / Lippincott / Williams & Wilkins. Page 248.






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