1. INTRODUCTION 2. INFECTION CONTROL IN DENTAL OFFICE 3. BASIC INFECTION CONTROL PROCEDURES 4. PERSONAL PROTECTION NEEDLE STICK INJURIES HAND CARE USE OF MASKS 5. CLEANING AND DISINFECTION OF OPERATORY DENTAL UNIT HAND PIECE ASEPSIS AIR WATER SYRINGES
X-RAY EQUIPMENT AND FILMS COUNTER TOP AND SURFACES 6. DISINFECTION OF IMPRESSIONS 7. DISINFECTION OF PROSTHESIS, CROWN AND BRIDGES 8. INFECTION CONTROL IN DENTAL LABORATORY. CLEANING AND DISINFECTION AIR VENTILATION/SUCTION SYSTEMS EQUIPMENTS/INSTRUMENTS FLOORS/SURFACES 9. CHARACTERISTICS OF DISINFECTING CHEMICALS 10. THE COMMANDMENTS OF PRACTICAL INFECTION CONTROL DENTISTRY 11. CONCLUSION 12. REFERENCES
INTRODUCTION Infection control has become a widely discussed topic in dentistry. Most of this discussion however has been devoted to general dentistry and oral surgery. Little has been written about infection control in a dental discipline such as
Prosthodontics. With the evolution of highly pathogenic and invasive micro organism, every specialty of dentistry carries its own risks. Research has now evolved in prosthodontics to directly relate the evidence concerning the pathogenicity and invasiveness of infectious diseases. Routinely dental care professional are at an increased risk of cross infection while treating patients. This occupational potential for disease transmission becomes evident initially when one realizes that most human microbial pathogens have been isolated from oral secretions. Because of repeated exposure to the microorganisms present in blood and saliva, the incidence of certain infectious diseases has been significantly higher among dental professionals than observed for the general population. Hepatitis B, tuberculosis and simplex virus infections are well recognized and indicate the need for increased understanding of modes of disease transmission and infection control procedures by dental care providers. The use of effective infection control procedures in the dental office and the dental laboratory will prevent cross contamination that may extend to dentists, dental office staffs, dental technician and patients. In this dental discipline there are two areas where the infection control protocol requires to be implemented. 1. Dental office 2. Laboratory
INFECTION CONTROL IN DENTAL OFFICE Dental office: The first step involves; •
Identifying high risk patients and sources of infection.
Understanding which disease has a high susceptibility for transmission and their routes of transmission.
Screening new patients prior to treatment by taking an oral and written medical history.
Continuing to update all patients’ medical histories at each recall appointment.
The following groups have been identified as high risk in relation to HIV and HBV: •
Any one with multiple sex partners and homosexuals.
Intravenous drug abusers.
Persons receiving transfusion of blood products.
Health care workers who may come into contact with blood saliva and other body fluid / secretions.
To set the standard of infection control it is necessary to have a knowledge about the microorganisms, their mode of spread and preventive measures against them and their habitats.
The pathogenic capabilities of the microorganisms depend on virulence, host resistance and concentration. At present most serious of these diseases are HBV and AIDS. HBV is a disease, challenging dentist and their staff. AIDS is a potential threat because of the increasing frequency with which AIDS patients seek dental treatment for intra oral symptoms.
HEPATITIS C It is transmitted through contaminated needles, syringes, contaminated blood and accidental needle stick HCV has been demonstrated in saliva The onset of HCV can be incidious with no clinical symptoms Prevention Measures recommended for HBV can be applied
HEPATITIS D HDV is also called delta hepatitis virus It cannot cause infection except in presence of HBV infection Prevention All measures used to prevent hepatitis B can be used HEPATITIS E
Formerly known as enterically transmitted non A non B hepatitis
HEV is transmitted by contaminated water, as well as person to person by the fecal, oral route
Sanitary disposal of waste
Hand washing especially before handling food
The second and third stage of AIDS may be detected by dentists undertaking oral and facial examination. However evidence suggests that the causative agent of AIDS is probably difficult to transmit during routine dental procedures. Studies have shown that the second and third stage of AIDS patients evidence a high infection rate with secondary infections like HBV, Herpes, candidiasis, oral hairy Leukoplakia, venereal diseases and TB. Disinfection and antisepsis: Antisepsis is a procedure which inhibits or destroys microbes on living tissues. Disinfection may also be used as antiseptics or vice versa depending on their toxicity. Various disinfectants used in dentistry:
Chlorhexidine etc. Methods of Disinfection:
1. Heat 2. Physical 3. Chemical Disinfection by heat
Boiling water Boiling water. If the boiling period is short bacterial spores can survive, boiling water is therefore inadequate for
sterilization of dental instruments. Heat sterilize all metal and heat-stable instruments that contact oral tissues, contaminated appliances, or potentially contaminated appliances should be heat sterilized after each use Examples: facebow fork, metal impression trays, burs, polishing points, rag wheels, laboratory knives
Physical methods-Ultrasonic: This is an effective way of disrupting microbial cell membrane and is used for removing debris before autoclaving. Chemical methods: Choosing a chemical disinfectant should be done carefully because a disinfectant used for one propose may not be equally effective for another. Further, the antimicrobial activity of a chemical disinfectant falls drastically in the presence of organic debris. Liquid Chemical Sterilant/Disinfectants Only for heat-sensitive critical and semi-critical devices
Powerful, toxic chemicals raise safety concerns
Heat tolerant or disposable alternatives are available
Mode of action of chemical disinfectant: Chemical used as disinfectant cause protoplasmic poisons in 3 different ways.
1. Membrane active disinfectant damages bacterial cell membrane (chlorhexidine, quaternary ammonium compound, alcohol phenols) 2. Fixation of the cell membrane and blockage of egress of cellular components (Formaldehyde and Gluteraldehyde) 3. Oxidizing agent - oxidize the cellular constituent (hypochlorite) Conditions determining the effectiveness of a disinfectant: 1) Spectrum of activity of the disinfectant vary widely Ex: some are more active against Gram +ve than Gram -ve bacterial 2 ) Satisfactory contact of the contaminated surface with the disinfectant for a specified period of time. 3) Organic Debris, air, greasy material prevent this so thorough cleaning before Disinfection is necessary. 4) Concentration- adequate concentration of disinfectant is essential and should be
for effectiveness. 5) Activity of disinfectant is often pH dependent (Ex: Glutaraldehyde acts only at alkaline pH, phenol at acid pH). 6) Neutralization : A wide range of substances including hard water soaps and detergent may neutralize the disinfectant. 7) Stability: All disinfectants are not stable especially when diluted and may deteriorate with storage. Solution should be freshly prepared and marked with an expiry date. 8) Speed of action varies according to the concentration used. Hypochlorite have rapid action but are corrosive at high concentration. Glutaraldehyde is slow acting but is an effective sporocidal agent. Potency of a disinfectant:
Disinfectant can be generally categorized as having high, intermediate or low potency depending on their ability
to kill various groups of organisms.
Those which can destroy mycobacterium groups are considered high potency disinfectant.
Ethyl alcohol or propyl alcohol (70%) alcohol combined with aldehyde is used in dentistry for surface disinfectant.
(is not recommended as it evaporates relatively quickly and leaves no residual effect) Aldehyde: Glutaraldehyde
It can be used either alone or in combination with others. Although less reactant than formaldehyde. It may cause
skin sensitization. Chlorhexidine
Antiseptic and plaque control agent -2% is used as dental disinfectant.
Its efficiency in the oral cavity is mainly due to absorption on to hydroxy apatite and salivary mucus.
Hypochlorite acts by releasing halide ions.
Corrodes metals and quickly in- activated by organic matter (betadine)
Each dental discipline is challenged by some what different organisms.
HBV, TB and AIDS are the serious ones.
TB may become a particular challenge to prosthodontic practice in future because the organisms are transmitted
in sputum and older persons are susceptible to acquiring the disease Basic infection control procedures: Practical points: To be simple, economical and easily understood by all staff. Preventive measures Risk areas 1.
Needle stick injuries--good technique
Contaminated waste------safe disposal
Most government entities, private agencies and health care professional organizations list six infection control procedures as mandatory for control of infectious diseases in dental practice regardless of disciplines. They are Dental treatment personnel (DTP) 1. All DTP should wear latex examination gloves during patient treatment 2. All DTP should wear protective eye ware during patient treatment. 3. All DTP should wear masks covering the nose and mouth 4. All items used in the oral cavity should be sterilized in a heat or heat pressure sterilizer whenever possible.
systems recommended for use in dentistry include chemical vapor sterilizers, dry heat sterilizers and steam
autoclaves 5. All touch and splash surface should be disinfected with an accepted disinfectant whenever sterilization is not possible.
Presently available chemical meeting these criteria are Gluteraldehyde, sodium hypochlorite, iodophors synthetic
phenolic compound etc.
6. Contaminated materials to be disposed off carefully by placing it in a sealed appropriate marked container. Incineration is desirable whenever available waste from high risk cases must be sterilized and then incinerated.
PERSONAL PROTECTION: 1. Needle stick injuries: Risk areas. Reheating local anesthetic needles. Washing blood contaminated instruments Handling instruments Prevention Use of needle guard. Bayonet technique (one handed introduction of needle into the sheath ] Treatment sequence for injuries:
Wash in running water and encourage wound to bleed
Cover the wound
Seek medical advice
Take blood sample from recipient
Prophylactic hepatitis B- Vaccine or hyper immuno gamma globulin are advised
Identify instrument or needle
Test for hepatitis B virus and HIV
Take blood sample from donor
Record details of injury in an accident book
Intact skin surface is the main barrier for protection against pathogens. The pH of skin is maintained by perspiration and the normal pH is between 5.5-6.5
At Higher pH 8, the keratin becomes weak and the skin surface is relatively porous
Damage to the skin is easily caused while handling laboratory equipment in prosthodontics. Cuts and burns can
easily occur which can predispose to infections such as dermatitis, psoriasis. Skin flora includes species of gram +ve cocci, belonging to staphylococcus, cornybacterium, yeast and yeast like fungi, staphylococcus aureus are regarded as transient and so are organisms like actinobacter and enterobacteriacea species. Hand care: Hand washing 1. Keep nails short 2. Remove jewellery
3. Cover all cuts and abrasions 4. Wet hands thoroughly 5. Apply disinfectant to palms, back-finger webs, then tips of fingers. 6. Rinse thoroughly 7. Dry thoroughly 8. Wash before and after each session 9. Use an emollient hand cream after each session. 10. Preferably use liquid soap rather than bar soaps Alcohol based hand disinfectants: 1. Similar to hand washing 2. Allow time for alcohol if visibly stained with blood or saliva 3. Do not use if hands is visibly stained with blood or saliva 4. Do not use in presence of naked flames Antiseptics used: 1. Chlorhexidine 2-14% with isopropyl alcohol of pH 5-6.5 2. Povidone iodine 7.5%-10% 3. Alcohols - ethyl and isopropyl alcohol 7% 4. Phenolic compound 5. Hexachlorophene - absorbed into blood through intact skin hence toxic with repeated use. 6. Parachlor meterylenol 2% (PCM) Gloves
Minimize the risk of health care personnel acquiring infections from patients
Prevent microbial flora from being transmitted from health care personnel to patients
Reduce contamination of the hands of health care personnel by microbial flora that can be transmitted from one
patient to another
Are not a substitute for handwashing!
The type of gloves available are latex, non-sterile and sterile
General purpose utility gloves
Surgeons sterile gloves
Non sterile latex gloves; Can be used for examination purpose. Prosthodontic treatment and laboratory work.
Gloves which are manufactured by a double dip, process have less irritating catalyzing coagulants.
Ideal gloves are those that are sterile and can be thrown away after use.
Cheaper gloves are less well fitting and tactile sensation may be lost.
Some are corrugated and dimpled for grip and are easier to wash.
Rewashing can decontaminate the gloves but after the washing the gloves deteriorate and the glove surface becomes sticky and porous. After contact with a patient, glove should be removed hand washed and disinfected and new gloves applied
again before treating the next patien Double gloving is recommended when thoperator has dermatological lesions, or when the patient is medically
Effect of latex gloves an manipulation of impression material;
Sulphur contamination from natural latex gloves inhibits the setting of addition silicone impression.
Latex gloves are not to be worn while mixing or handling vinyl polysiloxane putties
Putties should not be disposed while wearing latex gloves as the entire jar can get contaminated.
Latex gloves do not affect the setting of condensation silicone. Alternative suggestions are
Vinyl gloves without Sulphur containing stabilizers, used as over gloves. Should not be contaminated with powder
from latex gloves. Recommendations for Gloving
Wear gloves when contact with blood, saliva, and mucous membranes is possible
Remove gloves after patient care
Wear a new pair of gloves for each patient
Acts as a barrier against aerosol and splatter.
It is essential to wear a mask when using hand price air water syringe or ultrasonic sealer.
Washing contaminated instruments
An ideal face masks:
Should have a bacterial filtration efficiency of 95% or more
Does not contract nostril or lips
Has high filtration of small particles and tolerable, breath ability
Close fit around entire periphery
Do not cause fogging of eye glasses.
While using masks: 1. Use a new mask for each patient. 2. When a mask become wet replace it immediately or else it will collapse against the face and may not act as a barrier. 3. Remove mask with gloved hand and then discard both as contaminated waste. 4. Do not touch masks during procedure. If touched, hands should be washed each time. 5. Discard masks as soon as externally contaminated 6. Do not pull the mask down the face or leave it hanging around the neck . Type of masks available:
Simple paper masks-Limited protection due to poor fit.
Theatre type mask-Ineffective as a microbiological barriers.
Dome type mask-Close the nose and mouth completely not to wear
Essential against direct trauma, aerosols splatter debris.
Use protective glasses with side pieces
Coated safety glasses have the advantage of being fog and scratch resistant
Mask with face shield or visor can be used
Decontaminate used glasses with water and detergent and then with a tuberculocidal disinfectant which does not
attack plastic or later the ability to transmit light. Protective clothing: 1. Office coats wear a uniform or gown or coat 2. Change daily more often when visibly contaminated with blood 3. Long sleeves are more protective to the exposed areas from saliva and blood contamination. 4. Tuck the bottom of the sleeves into the gloves 5. Clothing should be made from light material with high collars, minimum of seams buttons or buckles.
6. Soiled clothing should be cleaned with hot water at 80° C for 10 mins using strong detergent and bleach if possible. Head covers: • Hair should be short and away from face " It should not interfere with vision or encroach on the operating area. • Head caps can be used during invasive procedure which are likely to involve extensive blood / saliva. Additional precautions; • Pre-treatment tooth brushing • 2% chlorhexidine as a pre-treatment mouth wash. • High volume aspiration • Correct use of rubber dam. • Efficient air filtration and ventilation laminar air flow and electrostatic precipitation units.
Cleaning and Disinfection of the operatory: Cleaning and Disinfection of the operatory is of vital importance in disease containment and infection control. The staff member in charge of this task carries a heavy ethical responsibility. Plan the office layout splitting it into. 1. Operators area 2. Dental assistants area 3. Sterilization and storage Utilities must be located at appropriate places, use separate sinks for hand washing and instruments washing preferably elbow and foot operated. Manual Cleaning
Soak until ready to clean
Wear heavy-duty utility gloves, mask, eyewear, and protective clothing
Washer-disinfector Decontamination of environmental surfaces:
The theory behind surface cleaning and Disinfection include the following.
Mechanical removal of organic debris (pre cleaning) " Wetting the surface with appropriate disinfectants and
Allow time for a residual effect of the disinfectant.
Disinfectants used: 1:10 solution of sodium hypochlorite (freshly prepared daily) iodophors mixed with distilled or sterile water synthetic phenol. Spray wipe spray: When cleaning remember to spray, wipe, spray the disinfectant solution. Use 4x4 gauze squares to wipe surfaces in overlapping strokes. Using a systematic pattern contact all surfaces at least twice. Then spray again. Allow the disinfectant solution to dry on the surface. Ideally wait for 10 mins. Surfaces to be disinfected: Surfaces that were touched during any procedure should be disinfected. These surfaces include any and all surfaces in the operatory. “ Light handles and switches Chair switches and stool levers Tubing attached to hand pieces, air water
syringe and high velocity suction system.
X-ray head and tube. Tray , tray arm and bracket table Counter tops, cabinet and drawers Clinical Contact Surfaces The dental unit:
Molinari suggests the following measures for controlling infection in the dental unit.
Flush your water lines for 3-5 mins and use this "spray-wipe - spray" technique on all "high touch" non sterilizable
surfaces and equipment . Allow at least 10 min for the Disinfection solution to air dry. Between patients;
Flush your water lines for at least 15 sec, sterilize or disinfect the hand piece and 3 way syringe.
Remove all disposable covers and disinfect all "high touch" areas with an approved surface disinfectant siphon
disinfecting solution through the high velocity evacuation system At the end of each day flush your water line for 3 mins run an ample amount of disinfection solution through the suction lines.
Disinfect the floor around the base of the chair use the "spray wipe spray" method on all counter tops and high
Weekly-Disinfect both inside and outside of all drawers and cabinets. Disinfect the entire floor of the operatory
and office laboratory. Hand piece asepsis: Sterilization is the preferred method of treating hand piece when possible. First flush the hand piece by running water thorough it for 20-30 sec. discharge the water into the sink or a container, next scrub the hand piece thoroughly with detergent and hot water to remove gross debris and adherent material. If the hand piece cannot be sterilized it must be high level disinfected with a chemical germicide which is tuberculoidal. Wrap the hand piece in solution soaked gauges and seal in a plastic bag or other impervious container. Leave undisturbed for the amount of time recommended by the manufacturer. Following completion of high level disinfection and prior to use. Remove any chemical residue by rinsing with sterile water or wiping the hand price with alcohol with alcohol soaked gauge. 1.Pre-manufactured disposable disinfectant sleeves: After flushing the hand piece place it an individual disinfectant hand piece sleeve.
which contains a combination of
alcohol and two synthetic phenols recognized by the EPA as a broad spectrum hospital grade antimicrobial agent as tuberculocidal seal the sleeve for 10 months. After 10 min or ready for the next patient clean the hand piece and blot it dry with a paper towel. 2. Latex sheath is a thin sheath of latex that covers all of the high speed
hand piece, except the bur.
It is disposed off after each patient and a fresh sheath is placed when disinfecting the operatory. Air / water syringes and ultrasonic sealers:
The units should be flushed as described for hand pieces. There attachments should be sterilized, if not possible
disinfected in the same manner as the hand pieces.
Scrubbing thoroughly, wiping with a disinfecting solution and removing any residue by rinsing with sterilized water
or wiping with alcohol. If possible removable tips should be used. X-ray equipment and films:
Protective covering or disinfectants should be used to prevent microbial contamination of collimating tubes.
Intraorally contaminated film packet should be handled in a manner to prevent cross contamination.
Contaminated packet should be opened in the dark room using disposable gloves.
The film should be dropped out of the packet without touching the film
The contaminated packet should be accumulated in a disposable towel.
After the packets have been opened they should be discarded and the gloves are removed.
Then films can processed without contaminating the dark room, equipment with microorganism from the patient.
Counter tops and surfaces that may have become contaminated with blood or saliva should be pre cleaned to
remove organic matter and their disinfected with a suitable chemical germicide. Disinfecting prosthesis crown and bridges 1. All to be washed carefully before placement into mouth, then disinfected. 2. After removal from mouth.
a. Ultrasonic cleaning for two min with a mild detergent or ultrasonic cleaning fluid.
b. Rinse under tap water, shake off excess water, immerse for 10 min inNaOCI or iodophors.
3. Antimicrobial agents incorporated in prosthetic materials to combat infections. a. Tissue conditioners sustained release system of antifungual agents (chlorhoxidine, clotrimazole) incorporated into tissue conditioners helps to treat denture stomatitis. b. Denture adhesives - hexa chlorophane c. Facial silicone elastomers Nystifin and clotrimazole in elastomers are effective against penicillin species. d. Tray adhesives - phenolic compounds 4. Antimicrobial rinses a. Chlorhexidine 2% Effects of disinfectants of prosthesis:
Idophor on Metal Corrosive on repeated exposure Change in flexibility of clasps due to tarnish and corrosion Glutaradehyde 2% and phenolic buffer change
disinfectant solution every day contra indicated.
Denture cleaners: Deposit of dentures
a. Soft debris b. Hard deposit of calculus essentially comprise of inorganic portion CaPO4, CaCOs Organic portion which bonds the deposit to
the denture comprises 15-30% of the total deposit, consist of micro
proteins. Requirement of cleansers:
Non toxic, bactericidal, dissolves organic and inorganic portions, shelf life, harmless to prosthetic materials.
Disinfection of impressions:
Impression must be rinsed to remove saliva, blood and debris and disinfected before being sent to the laboratory.
Saliva contains 10 bacteria / ml drained from mucosal surfaces and teeth. Simple washing removes 90% surface
bacteria. By disinfection 100% removal is achieved . Irreversible hydrocolloid: 1. 10 min immersion/spray with sodium hypochlorite 2. House hold bleach 1-10 dilution, iodophors, synthetic phenols by spray. 3. Do not submerge or soak in disinfectant, wrap the impression in a disinfectant soaked paper towel and place in a sealed plastic bag for 10 min. Remove wrapped impressions unwrap, rinse thoroughly shake excess water and pour the model. 4. Spray disinfection has a better antimicrobial effect. Does not affect the dimensional stabilities much as immersion. Impregnation of antimicrobial compounds into alginate Ex: Dimethyl ammonium chloride. Agar:
Sodium hypochloride 1:10 for 10 mins. ldophor1:213
Generally stable when immersed in standard disinfectants, rinse, in sodium hypochlorite 1:10 for 10min. Rinse
again to remove residual Water.
Disinfection the custom tray can interfere with the bond of some impression material to the custom tray. Polyether:
Prolonged immersion surface leads to distortion
If longer than 10 mins dimensional changes occur due to hydrophilic nature.
Short term disinfection can affect the surface properties of impression materials.
To minimize dimensional change with Polyether impressions a chlorine compound product with a short
disinfection time (2-3 months) should be selected or impression should be disinfected with spray. Additional silicone:
Susceptible to damage to neutral gluteraldehyde immersion longer than 15 min. hydrophilic become hydrophobic.
Spray is best for additional silicone
Unaffected by immersion disinfectant 2% gluteraldehyde satisfactory sodium hypochlorate 1:10 Disinfection of gypsum casts: 1. Additional of disinfectant to the water 2. Additional of disinfectant to the water + over night gas sterilization but
it is impractical for routine use.
3. Disinfectants incorporated into gypsum cast Iodophors 1.76 for 1hr Phenol 5% NaOC15.25% effective at 1 hr Gluteraldehyde 2% 4. Chloramine, T 0.25% has also been added to dental stone used for pouring irreversible hydrocolloid impression. Disinfection of pumice:
Add three parts of green soap to the disinfectant solution (5 parts of NaOC 1 to 100 parts of distilled water) before mixing the pumice.
This helps to keep the pumice suspended , pumice must be changed daily and the lathe should disinfected unit
doses of pumice may be used in each case and then discarded. Change pumice daily Machine should be cleaned and disinfected daily No need for separate pans for new and existing prostheses if isolated properly At a minimum clean and disinfect pumice brushes and rag wheels daily. Daily heat sterilization is preferable . INFECTION CONTROL IN THE DENTAL LABORATORY Infection control in dental laboratories has attracted increasing interest. Several well documented instances have prove that persons can contact infection disease by handling contaminated materials. Thus dental lab personnel have the moral and legal responsibility to prevent cross contamination via the dental lab DENTAL LABORATORY
All disinfection procedures are accomplished prior to delivery to lab
Done in dental operatory or professional work area
Recommend a sign and monitor system be implemented stating “Only Biologically Clean Items Permitted”
Clean and disinfect before delivery to patient
After disinfection: rinse and place in plastic bag with diluted mouthwash until insertion
Do not store in disinfectant before insertion
Label the plastic bag: “This case shipment has been disinfected with ______ for _____ minutes
Cleaning and disinfection: Effective cleaning and disinfection will help to maintain a sanitary environment as well as to minimize the
potential for cross contamination of infectious diseases via the laboratory. All laboratory personnel must observe procedures that maintain a hygienic and sanitary environment.
Utility gloves that are puncture resistant must be worm to protect hands from contamination by pathogens
Laboratory sanitation measures must include this following areas
Air ventilation and Suction system
Equipmentsa and instruments
Floor and surfaces. Air ventilation / suction systems:
Air ventilation filters and vacuum bags or suction unit filters should be changed and / or cleaned regularly to
improve their effectiveness and efficiency. Equipments / instruments;
Laboratory personnel should clean and disinfect equipment and instruments that have been contaminated by
pathogens. Such laboratory equipments and instruments include grinding lathes , hand pieces ,ultra sonic units, packing boxes, trash containers, utility gloves, pumice pans, laboratory pans, protecting eye wear, vibrator, cast trimmers, articulators, face bow transfers, quick polymerization unit pots burs and stones, polishing rag wheels , bristle brushes ,mixing bowls and spatulas. Research data have shown that external surface of laboratory lathes and hand pieces can be disinfected using surface disinfecting chemicals laboratory personnel should follow the lathe and hand piece manufactures instruction for proper maintenance cleaning disinfection and compatibility with disinfecting chemicals hand piece should be heat sterilized if possible. 1. Thoroughly scrub the external portion of the lathe and or hand-piece with detergent or disinfectant and rinse with water to remove adherent materials. 2. Thoroughly spray or wipe lathe and /or hand piece with absorbent material (Ex; disposable paper towel) saturated with a surface disinfectant that is recommended by the manufactures. Allow at least a ten months contact time and then rinse
with water and dry. Make sure that the surface disinfecting chemicals being recommended by the lathe and / or hand piece manufactures is an accepted procedure. 3. Depending on the lathe and/or hand piece, apply lubrication before use (follow manufactures instructions). 4. Use plastic wrap, aluminum foil, or other materials impervious to water to cover the cleaned and wiped lathe and / or hand piece. Replace the cover after each use. Floors/surfaces: The laboratory personnel should be required to clean and disinfect floors and other surfaces: generally all
surfaces should be cleaned and disinfected at the end of each work day, other significant practices include. 1. Using disposable over gloves when answering a telephone call if interrupted while performing a task requiring glove wearing. 2. Avoid from eating drinking applying cosmetics or lip balm and handling contact lenses at prohibited areas in the dental laboratory or work areas when there is potential for occupational exposure 3. using stone that has not been poured against an impression to make slurry water. 4. Mixing polishing pumice with antiseptic liquid soap. 5. Using puncture resistant utility gloves to retrieve items immersed in disinfecting solution. Avoid using disposable gloves because disinfecting solutions cause deterioration of glove materials, resulting in minute punctures in the gloves during laboratory procedures there by contaminating the hands. 6. Refraining from placing the ceramic brush in the mouth when building ceramic restorations 7. Refraining from using saliva to polish a wax pattern. 8. Replacing contaminated pumice after each use when polishing repaired and new prosthesis. 9. Replacing expired disinfecting solution according to the manufacture's instructions. 10. Using separate pumice pans for polishing repaired and new prosthesis as indicated. 11. Using spray bottle instead of gauze and other applicators to carry disinfecting solutions when cleaning and disinfecting. The rationale for using spray bottles is to allow the disinfectant to better penetrate equipment crevices. Additionally, spray bottles protect the disinfectant solution from being activated or absorbed by gauzes disposable paper towel or sponges. 12. Diluting disinfecting solutions with water following the manufacturer's instructions to prevent impairment of the cleaning and disinfecting efficiency. 13. Using mechanical shell blaster only on disinfected dental items. It is important to use effective disinfecting chemical that have the ability to penetrate and preclean contaminated surfaces such surface disinfecting chemicals include iodophors phenolicm, chlorine solutions and gluteraldehyde etc.
Disinfecting chemicals should indicate on the label that they kill mycobacterium tuberculosis.
This is significant because the tubercle bacillus is an intra cellular bacteria! parasite that presets a sever
challenge to chemical disinfectants used in dental offices and laboratories and is considered to be the next most resistant micro organism after bacterial endospores. The mycobacterium tuberculocidal action assures that the product is an intermediate or highest level disinfectant and that it will destroy all pathogenic potentially threatening dentistry. Disinfecting chemicals should also posses the following additional characteristics. 1. The widest possible antimicrobial spectrum 2. A rapidly lethal action on all vegetative forms and spores of bacteria and fungi, protozoa etc. 3. Activity in the presence of organic matter such as blood, sputum and compatibility with soap detergents and other chemicals encountered in use. 4. A non-corrosive nature especially with regard to instruments, equipment and other metallic surfaces. The disinfection also should not alter the integrity of impression materials Ex: dental stone. 5. A resident effect to combat pathogens on treated surfaces. 6. Easy to use 7. A pleasant odor affordability The commandments of practical infection control in dentistry: Today's minimum requirements for a practical dental office infection control / exposure systems. Each dental facility should have a comprehensive exposure control plan. The written exposure control plan should address the following things. 1. Information and training 2. Universal precaution 3. Exposure determination 4. Hepatitis B vaccination 5. Personal protective equipments 6. Engineering and work practice control 7. House keeping 8. Post exposure evaluation and follow up 9. Medical records 10. Biohazard communication Information and training:
Employers shall ensure that employee with occupational exposure participate in a training program that must be
provided at no cost to the employees and during working hrs. Universal precautions:
Universal precautions shall be observed to prevent contact with blood and other potentially infections materials.
Under circumstances in which differentiation between body fluid types is difficult or impossible all body fluid must be considered potentially infections. Exposure determination: Each employer who has employees with occupational exposure must prepare an exposure determination which shall contain a list of all job classification in which all employees have occupation exposure and a list of all tasks and procedures in which occupational exposure occurs. This exposure determination shall be made without regard to the use of personal protective equipment Hepatitis B vaccination:
The employer shall make available hepatitis B vaccine and vaccination series to all employees who have
occupational exposure. This must be provided at no cost to the employee and at a reasonable time and place. Personnel protective equipments:
The employer shall provide at no cost to the employee appropriate personal protective equipments such as
gloves, gowns, laboratory coats, face shield masks and eye protection etc. Engineering and work practice controls:
Engineering and work practice control shall be used to eliminate or minimize employee exposure. The
engineering and work practice control in effect must be examined at regular intervals to ensure their continued effectiveness. House keeping:
Employee shall ensure that the worksite maintained in a clean and sanitary condition
Post exposure evaluation and follow up: After a report of an exposure incident the employer immediately shall offer the exposed employee a confidential medical evaluation and follow up. Medical records:
The employer shall establish and maintain an accurate medical record for
exposure. Biohazard communication:
each employee with occupational
Wearing labels or color coding shall be used on containers of regulated waste, refrigerators and freezes
containing blood or other potentially infections material and other container used to store, transpo
CONCLUSION Dental officer and commercial laboratories should work closely together to co-ordinate control of potential cross infection between the two disciplines. The control of infectious disease in prosthodontics is not difficult. Dental personnel have the moral and legal responsibility for protecting himself, his patient from infectious disease.