During dental filling, tooth extraction, dental prosthesis, tooth cleaning, orthodontic correction and oral surgery, various dental instruments are in direct contact with the patient's saliva, blood, gums, oral mucosa and may pierce the oral tissue. Diseases that spread through blood, such as hepatitis B, hepatitis C, AIDS and etc., spread through dental instruments stained with patient's blood and saliva and the contaminated hands of the medical staff, and casue cross-infection.

All following situation can easily lead to cross infection of patients and medical staff.

• Lack of strict aseptic operation concept
• Lack of personal protection awareness
• Do not wear masks, eye masks or gloves
• Do not change gloves when treating the next patient
• Do not pay attention to hand washing
• Accidental sharp stab wounds at work

Regular dental hospitals or clinics all have special cleaning and disinfection rooms, which take the disinfection and sterilization procedures and methods according to the flow process from dirty to clean. The disinfection and sterilization of all medial equipment in dental clinnics are carried out according to the double disinfection procedure. All instruments that come into contact with the patient's wound blood are autoclaved, sterilized and packaged separately. Each instrument can only be used by one person and then must be steriized. Lamp handle set, head cover, barrier film on treatment table must be replaced before the next patient is treated. One patient, one use and one replacement. Medical personnel are required to strictly observe medical routines to prevent cross-infection.

In the treatment of oral diseases, it is necessary to prevent the disease from being transmitted from the medical staff to the patient, and to prevent the disease from passing from the patient to the medical staff. Effective protective measures should be taken for the patient and the medical staff. The medical staff and workers must wear gloves during the diagnosis and operation. And the gloves should be replaced before the next patient is treated. After operation, take off the gloves, wash hands with soap and disinfectant. Medical staff should wear masks, hats and eye masks when necessary to prevent contamination of infectious gases.

9 tips to prevent cross-infections:
1. In order to prevent cross-infection in hospitals, the disinfection and sterilization of all medical instruments in the dental clinics must be carried out according to the double disinfection procedure. Only good disinfection standards will not lead to iatrogenic cross-infection.

2. Any device that touches the blood of a patient's wound, such as a silver-mercury filling device, a nerve broach, an enlarge needle, a dental forcep, a tooth shank, an osteotome, a scalpel, a periodontal scraper and etc., must be subjected to high temperature and high pressure disinfetion sterilization after one use.

3. All water-gas gun heads that enter the patient's mouth must be replaced after one use by one patient. Materials such as mechanic materials, dental molds and etc. need to be disinfected in chlorine-containing disinfectants. And devices, such as occlusal apparatus, fixed or active restoration and orthodontic appliances, need to be cleaned and disinfected before being placed into the patient's mouth.

4, The use of dental handpieces must be “one handpiece for one patient only”. Mouth mirror, tweezers, probes and etc. are all packed individually in one bag after disinfection and sterilization and each set is for one patient only. The burs, fillers, trays and etc. are all sterilized after being used by one person for once. Instruments that are not resistant to high temperature should be sterilized by chemical sterilizing agents.

5, Doctors are strictly required to wash their hands before wearing gloves and to replace gloves before treating each patient. During treatment, doctors must not answer calls, write cases, or touch items with gloves.

6, The head cover on the treatment chair and the barrier film on the lamp handle and the treatment table must be replaced for each new patient. Disposable dental instruments, cups, syringes, mouth mirrors, tweezers, probes, small brushes, strong suction devices, suction devices and other devices should be used more.

7. Strictly execute the disinfection and isolation system. Master the aseptic technique, and use the controllable air disinfection machine to regularly sterilize the clinic environment after work every day. Strictly observe the aseptic operation rules and strengthen the personal protection of medical staff. The dental clinic must be kept it clean. Irradiate the clinic with ultraviolet light after each working day and keep the clinic well ventilated. The treatment table should be disinfected with a chlorine-containing disinfectant after treating each patient. The surface of comprehensive treatment chair and the work table that are contaminated by patients’ blood, saliva or other secretions must be wiped with a chlorine-containing disinfectant after the treatment.

8. Shooting and rinsing of dental X-rays: Barrier protection and surface disinfection should be performed when shooting and rinsing X-sheets. Use barrier protection when adjusting the position of the lens camera, adjusting control panel parameters, and operating the machine. Gloves should be worn. If there is a possibility of blood or body fluid splashing, other protective measures such as masks, goggles and protective clothing should be added.
When rinsing photos with a darkroom: Use a paper towel to wipe off the saliva and blood from the film bag, open the film bag (dirty) in the darkroom, and place the clean film inside on a clean paper or barrier to ensure that it does not contaminate the film. Wear a new pair of gloves for film rinsing.
When rinsing photos without using a darkroom: When washing photos without using a darkroom, you need to be more careful to prevent cross-contamination. Wrap the film bag with a barrier material before filming, and remove the barrier material after filming, so that the clean film bag falls on a clean surface. Replace a pair of gloves for subsequent flushing.

9. Disinfection of handpieces: Most handpieces cannot tolerate ultrasonic cleaning. But since the debris/microorganisms in the oral cavity may be sucked back into the lumen of the handpiece, the inside of the handpiece must be cleaned before sterilization.
The general steps for handpiece cleaning process are as follows:
(1) After the treatment is finished, do not remove the handpiece immediately. Clean the dirt on the surface of the handpiece and rinse the lumen for 20-30 seconds.
(2) Take down the handpiece and thoroughly clean its outer surface with water or detergent, then rinse and dry. Do not soak unless specifically stated by the manufacturer.
(3) Clean/lubricate the lumen of the handpiece according to the manufacturer's instructions. Different handpieces have different requirements for lubrication timing. There are lubricate before sterilization, lubricate after sterilization, before/after sterilization or no lubrication. It should be carried out according to the manufacturer's requirements. Lubricating oil tanks that are lubricated before and after sterilization should be separated.
(4) Wipe off excess oil on the surface of the handpiece. For handpieces equipped with fiber optics, make sure that there is no lubricant at the fiber touch parts.
(5) Packed in paper plastic bags, paper bags or containers.
(6) Sterilize according to the manufacturer's instructions.
(7) If it is necessary to lubricate after sterilization, it must be carried out aseptically.