THE IMPLANT SOCIETY
The Importance of Asepsis in Dental Implantology
By Arun K. Garg, D.M.D., Sanjay N. Reddi, D.D.S.,
and Guillermo E. Chacon, D.D.S.
The importance of asepsis in the long-term success of dental implant procedures can not be over- emphasized. Maintaining an aseptic field - one that is free from infection, septic material, or contact with microorganisms - during the placement of implants in the oral cavity is critical for preventing postoperative infections and rejection of the fixtures by the body. To achieve this goal, dental surgeons are obligated to provide a clean and safe operating environment for their patients. Today, most dental implant surgeries are performed on an elective, outpatient basis. The procedure can be carefully planned since it is not an emergency, and is done using a local, regional, or general anesthesia without having to hospitalize the patient overnight.
INSTRUMENT CARE
To prevent postoperative infections or patient cross contamination, implant surgical instruments should be handled and stored following strict sterilization procedures and controls. Sterilization is the complete destruction or elimination of all living microorganisms, accomplished by physical methods (dry or moist heat), chemical agents (ethylene oxide, formaldehyde, alcohol), irradiation (ultraviolet, cathode), or mechanical methods (filtration). Disinfection, which reduces or eliminates infectious organisms, does not necessarily kill all microbes. The fear of AIDS and other blood-borne diseases has the general population demanding that all items used on HIV-infected patients and potentially infected patients be sterilized between use. The World Health Organization (WHO) has estimated that between 8 and 10 million people worldwide are infected with HIV, and predict this number will rise to 95 million by the year 2000.
After instruments have been used on one patient, they must be thoroughly cleaned before they can be sterilized. If an item can not be cleaned properly, it can not be sterilized. Special care must be given to the surgical burs because of their intricate shapes. Bone drills may serve as reservoirs for microorganisms that could be subsequently inoculated directly to a patient during bone drilling. Sterilization methods must be used to process these instruments rather than disinfection alone.
Although universal precautions dictate sterilizing all invasive surgical equipment, many of the current methods of sterilization are not compatible with the delicate, intricate instruments used during implantation that require a quick turnaround. The time-honored method of steam sterilization can not be used for items that do not tolerate heat. Ethylene oxide (ETO) gas can be used for these delicate items, however, to complete sterilization and aerate the items to remove residual ETO gas requires 10-24 hours. Thus, the dental surgeon could consider other methods of sterilization that are available, besides steam, heat, and ETO. Those that could be applied to oral implant instruments include electron-beam sterilization, sterilization filtration, ultraviolet irradiation, ionizing irradiation, and percacetic acid (the newest method of sterilization available today).
PREOPERATIVE PREPARATION
Preoperative preparation of patients undergoing surgical placement of dental implants is aimed at reducing the number of pathogens at the surgical site. Doing so eliminates or minimizes sources of contamination, prevents infection, and improves the patient's general resistance. The patient should be free of remote infections (e.g., periodontal diseases, acute or chronic respiratory tract infections, and chronic sinusitis in the head or neck region) that could significantly increase the risk of infecting operating wounds if left untreated. It is also prudent to ensure that patients have received adequate medical treatment for associated noninfectious conditions, such as diabetes mellitus and cirrhosis of the liver, that could delay or impede wound healing and repair.
Immediate Preoperative Preparation
Once the patient is seated comfortably in the operating room, set steps are taken to help keep the surgical field clear and free of contamination. The surgical field comprises the patient's entire face, extending from the infraorbital region, across the periauricular region, over the angle of the mandible, and down to the clavicles. The patient's hair is covered with a surgical cap; the head is then draped with a sterile towel to ensure that the hair, ears, and eyes are covered; and towels are placed at the sides of the patient's head to collect excess disinfectant.
Disinfection of the Patient's Skin
The concept of preparing a patient's skin for surgery was first introduced more than a century ago. However, despite advances in our knowledge of skin flora and the effects of antiseptics on infection, the procedures for skin preparation remain the basically the same today as when they were first originated. In the "Recommended Practices for Skin Preparation of Patients" by the Association of Operating Room Nurses (AORN) the stated goal of preoperative skin preparation is to decrease the risk of postoperative wound infection by removing soil and transient microorganisms from the skin, reducing the resident microbial count to subpathogenic amounts in a short period of time and with the least amount of tissue irritation, and inhibiting rapid rebound growth of microorganisms.
Although approximately 20% of the resident skin can not be removed by surgical scrubs and antiseptics, it is not possible to sterilize the skin without damaging it. Therefore, the most that can be done to minimize the contamination of wounds is to disinfect the skin using sterile gloves. Transient flora are usually superficial and can be removed by washing the skin with soap and water or a mild disinfectant. Resident flora, however, are deep-seated and adherent, requiring stringent disinfection. Commonly used disinfecting agents include iodine, povidone iodine, chlorhexidine gluconate, and 70% isopryl alcohol.
In 1993, Arata et al. Reported that when povidie-iodine alcohol solution was used to disinfect the skin there was a higher reduction factor in the total resident flora, and that the solution was a reasonable and effective antibacterial agent for preoperative skin preparation.
Surgical Scrub
Transient or resident skin flora includes Beta hemolytic streptococcal, Staphylococcus aureus, Pseudomonas, Escherichia coli, and Klebsiella, among others. Staphylococcus is the most common resident flora. Hand scrubbing with a disinfectant agent most readily removes transient flora, but resident flora are more difficult to remove. For optimal effect, five to ten minutes of hand scrubbing is recommended. Anti-septics widely used for hand scrubbing include lodophor (BETADINE), Chlorhexidine (HIBICLENS), and Hexachlorophene.
The following protocol should be followed by the surgical team to disinfect the fingernails, finger, arms, and elbows. It is done prior to donning a sterile gown and gloves and surgically scrubbing the operating field.
- Wash your hands, arms, and elbows with soap and water for two minutes using a sterile brush to remove surface fats, debris, and cells.
- Use a nail file to meticulously clean your fingernails under running water for one minute.
- Impregnate a sterile brush with a disinfectant solution and scrub the entire surface of your fingers, fingernails, hands, arms, and elbows in that order.
- Then rinse thoroughly under running water until all excess solutions are washed away. Allow the excess water to drip by holding your hands above flexed elbows for three minutes.
- Repeat the scrubbing and rinsing procedures for three minutes.
Preparation of the Surgical Field
The "prep-table" should be covered with a sterile drape and supplied with gloves , towels, sponges, and a bowl of disinfectant. A scrubbed and ungowned surgeon or assistant then removes surface dirt, loose skin, and debris from the surgical site by scrubbing the patient's skin with soap and water. The surgical field is scrubbed in a circular fashion - from the center to the periphery - and dried with sterile, disposable paper towels. Next, the patient's skin is disinfected using sterile sponges and the previously mentioned disinfectant agents. The skin is "painted" from the center of the surgical field to the periphery and allowed to air dry. After donning a sterile gown and gloves, the surgeon drapes the patient to demarcate the surgical field and keep the patient warm (Figs. 1-17). The surgery may then proceed.
OPERATING ROOM
Attire
One of the most important advances in surgery in the last century was the realization that a significant number of postoperative infections could be prevented by the combining the intraoperative use of sterile techniques and garments. The most common source of infection during surgery are operating room personnel. Thus, the emphasis is to keep the skin microorganisms of the surgical team away from the surgical site. Sterilized gowns and caps were first reported to be used in the operating room by Gustav Neuber in 1883. As early as 1952, however, Beck and Collette noted severe limits to the worthiness of the gowns then being used by surgeons. Despite their apprehensions and those of a few other critics, though, the choice of gowns was based mainly on comfort and cost.
An aseptic barrier can be defined as any material placed between the surgical incision and a possible source of bacteria, with the intention of preventing their passage into the sterile zone. All surgical personnel wear sterile, disposable caps and masks to minimize the possibility of introducing bacteria-laden droplets from nasal and oral cavities, desquamated epithelium and dandruff from the hair and scalp into the operating room environment. Because clothing gives off lint and dust, sterile disposable gowns (traditionally of 140 thread cotton muslin) are used to minimize contamination of the surgical field. Gloves made of latex are used during surgery. Any time a glove suffers a slight prick or catch, it should be treated as a tear in the glove and the glove should be changed.
Operation Room Environment
Most postoperative wound infections are due to seeding by endogenous bacteria, however, exogenous bacteria have also been frequently implicated. Sources of exogenous bacteria include operating personnel, anesthesia equipment, the operating table, operating lights, wall and floor surfaces, furniture, instruments, supplies, and air in the surgical suite. Certain areas in the operating room may become heavily contaminated with pathogens because they are difficult to clean, often due to poor access. Ideally, the floor should have a homogenous surface free of grooves and fissures.
The operating room should not only be clean but free of dust. Airborne counts should not exceed one bacteria per square foot. A simple test can be performed periodically to ensure cleanliness in the operating room if a staff member, wearing black stockings, walks across the floor and accumulates visible fuzz on the stockings, the room contains an excess of dust. Dust can usually be controlled by improving air filtration. In addition, phenolic detergents are recommended for wet vacuuming floors.
Effective and efficient air conditioning systems should be used to eliminate airborne microbial contamination. Studies have shown that airborne bacteria account for 98% of the bacteria found in wounds postoperatively when the surgery was performed in a conventionally ventilated room. Use of unidirectional airflow with the operating room, and occlusive surgical clothing, reduce airborne bacteria by about 100 times and wound contamination by 30 times. Air conditioning systems must be properly and regularly maintained. Otherwise, inefficient ventilation systems and poor filtration can result in rebreathing of contaminated air and lead to upper respiratory tract infections.
Other measures that can be taken to minimize the risk of infection include having the surgical team keep their movements and speech to a minimum, and to restrict visitors to the operating room.
STERILIZATION AND DISINFECTION
Commercial autoclaves are indispensable in any surgical practice. Autoclave produces moist heat in the form of saturated steam under pressure and provide the crucial elements of asepsis (sterilization and disinfection). Often, during surgery, rapid sterilization of an instrument is required when an instrument is inadvertently omitted from the surgical pack or when it is accidentally dropped on the floor. A small steam sterilizer provides a highly effective means of emergency sterilization that is far superior to the relatively ineffective and potentially compromising method of cold sterilization.
Before sterilization, the instrument is washed with a brush and soapy water, placed unpacked in the perforated metal tray on the shelf of the sterilizer, and locked in the machine. Steam enters the machine for 40 seconds until the temperature rises to 1310C or 270F. During operation, a steam pressure of 27 PSI is maintained.
After three minutes, the steam is released and the instrument is ready for use. Sterilizers must be constantly monitored with temperature sensors or biological indicators to ensure their efficacy
SUMMARY
All surgical procedures, including dental implantation, involve certain risk factors. One of the most common is that of postoperative infection. The harsh realities of today's medical environment such as the threat of blood-borne pathogens and transmittable infections, the increased cost of hospitalization, and the increase in malpractice suites against surgeons, make it imperative that all surgeons follow safe and sterile surgical protocols that reduce the chances of infections and ensure satisfactory results.
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