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Oral microbial flora /certified fixed orthodontic courses by Indian dental academy


The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit ,or call

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  • 1. ORAL MICROBIAL FLORA INDIAN DENTAL ACADEMY Leader in continuing dental education
  • 2. contents Introduction and history Morphology of bacteria/viruses/fungi General concepts of pathology Host-parasite interaction Immunity in the oral cavity Development of oral flora Factors affecting development of oral flora The normal microbial flora of different sites of the mouth
  • 3. The principal microorganisms of the mouth Dental plaque Dental caries and periodontal disease Bacterial/ viral/fungal infection of oral soft tissues Prosthodontic considerations Infection control in dental laboratory and dental clinics Conclusion References
  • 4. The Normal Flora Our bodies are like mobile warmblooded coral reefs, rich in microbial biodiversity and home to vast numbers of bacterial cells there are more bacterial cells (1014) associated with the human body than there are human ones (only 1013)! composition of normal flora varies from individual to individual some bacterial species carried only transiently most fairly permanent
  • 5. Disease can come about in several overlapping ways 1. Some bacteria are entirely adapted to the pathogenic way of life in humans. They are never part of the normal flora but may cause subclinical infection, e.g. M . tuberculosis 2. Some bacteria which are part of the normal flora acquire extra virulence factors making them pathogenic, e.g. E. coli 3. Some bacteria which are part of the normal flora can cause disease if they gain access to deep tissues by trauma, surgery, lines, e.g. S. epidermidis 4. In immunocompromised patients many free-living bacteria and components of the normal flora can cause disease, especially if introduced into deep tissues, e.g. Acinetobacter
  • 6. What are bacteria? Bacteria are single cell organisms that are found living throughout our world. Bacteria eat everything from sugar, starch, sulfur and iron. There's even a species of bacteria—Deinococcus radiodurans—that can withstand blasts of radiation 1,000 times greater than a human being could survive!
  • 7. Typical Bacteria Structure Flagellalocomotion, flagellin(protein ) Fimbriae- helps in adhesion Calpsule-mucoid envelope, resists phagocytosis, forms hapten Cellwall-outermost layer Cytoplasmic membrane cytoplasm
  • 8. Types of Bacteria Microbiologists classify bacteria according to their shape: spherical, rod-shaped, and spiral-shaped. Coccus Bacillus Spirillum
  • 9. Bacteria may be further classified according to whether they require oxygen (aerobic) or no oxygen (anaerobic) Bacillus anthracis Peptostreptococcus Aerobic bacteria Anaerobic bacteria
  • 10. Morphology of viruses Viruses are obligate intracellular parasites Do not fall strictly into the category of unicellular microorganisms as they do not possess a cellular organisation They contain only one type of nucleic acid either DNA/RNA but never both Much smaller than bacteria Largest abt 300nm, poxviruses Smallest abt 20nm,parvoviruses Nucleicacid core surrounded by a protein coat, the capsid Capsid functions to introduce viral genome into host cells by adsorbing readily to cell surfaces DNA VIRUSES- poxvirus,herpes virus, adeno virus, papova virus RNA VIRUSES- picorna virus, orthomyxo virus, paramyxo virus, retro virus, toga virus
  • 11. Morphology of fungi Unicellular with oval/spherical cells 2-5 micro mt Produce a pseudomycelial form comprising of a network of interlacing filaments
  • 12. Normal Microbiota Animals are generally free from microbes in utero. After birth, microbial populations rapidly establish themselves in the newborn’s body. Feeding and breathing introduce many more microbes.   E. coli and other bacteria colonize large intestine. Candida albicans colonizes mucous membranes. Normal Microbiota or Flora: Microorganisms that remain throughout an individual’s life. Transient Microbiota: Microorganisms that are present for a certain time period and then disappear. Cells in human body: 1 x 1013 Microbes associated with human body: 1 x 1014 There are ~10 microorganisms/human body cell.
  • 13. Most complex and diverse……. Oral cavity provides ideal enviornment… Why care about the normal flora? colonization resistance: competition for space and nutrients with pathogens release of bacteriocins and colicins (antibacterial substances) to prevent pathogen growth vitamin K production in gut continued antigenic stimulation from commensals cross-reacting protective immunity against pathogens commensal neisseriaceae and Neisseria meningitidis
  • 14. Why care about the normal flora? commensal bacteria may cause disease at their site of carriage or nearby, e.g. Streptococcus mutans (mouth)  causes dental caries Streptococcus pneumoniae (upper airways)  causes otitis media, sinusitis Some members of the normal flora can become pathogenic if they acquire additional virulence factors (e.g. E. coli) or are introduced into normally sterile sites (e. g. Staphylococcus aureus)
  • 15. Interaction Between the Normal Microbiota and the Host SYMBIOSIS: “Living together”. 1. Commensalism: One organism benefits, the other is not affected (+/0).  Many microbes live off secretions and dead cells and do not benefit or harm host. 2. Mutualism: Both organisms benefit from living together (+/+).  E. coli synthesizes vitamin K and some B vitamins. 3. Parasitism: One organism benefits, the other is harmed (+/-).  Most disease causing bacteria.
  • 16. Opportunistic Pathogens The nature of symbiotic relationships can change. Opportunistic Pathogens: Organisms that normally do not cause disease in their natural habitat in a healthy person. They may cause disease if the host is weakened or if they enter a different part of the body. Pneumocystis carinii pneumonia in AIDS patients. Tooth decay and gum disease caused by mouth flora. Neisseria meningitidis is usually harmless in respiratory tract, but can cause meningitis.
  • 17. Etiology of Infectious Diseases Diseases can be caused by many factors: infection, genetics, degeneration, and others. Koch’s Postulates Developed by Robert Koch in 1877 to establish cause of infectious diseases: anthrax and TB. 1. Same pathogen must be present in every case of the disease. 2. Pathogen must be isolated from diseased host and grown in pure culture. 3. Pathogen from pure culture must cause disease when inoculated in healthy, susceptible laboratory animal. 4. Pathogen must be isolated from inoculated animal and shown to be the original organism.
  • 18. Koch’s Postulates for Infectious Diseases
  • 19. Exceptions to Koch’s Postulates Koch’s principles do not apply to all diseases. 1. Some microbes cannot be cultured in artificial media.  Treponema pallidum (syphillis)  Mycobacterium leprae (leprosy)  Ricketsias, chlamydias, and viruses only multiply within cells. 2. One disease may involve several different pathogens.  Diarrhea  Pneumonia  Meningitis  Nephritis 3. Some pathogens may cause several different diseases.  Streptococcus pyogenes: Scarlet fever, sore throat, skin infections, bone infections, etc..
  • 20. Transmission of Disease I. Contact Transmission: Spread by direct contact, indirect contact, or droplet transmission. A. Direct Contact Transmission: Person-to-person transmission. No intermediate object is involved. Examples: Touching, kissing, sexual intercourse. B. Indirect Contact Transmission: Agent is transferred via a nonliving object (fomite). Examples: Towels, eating utensils, thermometers, stethoscopes, bedding, clothes, money, and syringes. C. Droplet Transmission: Microbes are spread in mucus droplets that travel short distances (less than 1 meter). Examples: Sneezing, coughing, talking, and laughing.
  • 21. Transmission of Disease (Continued) II. Vehicle Transmission: Transmission of disease via medium such as water, food, air, blood, body fluids, and intravenous fluids.   Waterborne Transmission: Usually caused by water contaminated with sewage. Airborne Transmission: Spread of agents by droplets in dust that travel more than 1 m to host. III. Vectors: Animals that carry disease from one host to another. Arthropods (insects) are most important animal vectors.   Mechanical Transmission: Passive transport of pathogens on insect’s body. Biological Transmission: Pathogen spends part of its life cycle in the vector.
  • 22. CHAIN OF INFECTION All links must be connected for infection to take place Pathogen (sufficient virulence & adequate numbers) Susceptible Host (allows pathogen to survive & multiply) (i.e., one that is not immune) Entry Source Mode (of transmission from source to host) (portal that the pathogen can enter host)
  • 23. Nosocomial (Hospital Acquired) Infections “Nosocomial” Greek word for hospital. Infections acquired at a health care facility. According to Center for Disease Control (CDC), 5-15% of all hospital patients acquire N.I.s. Predisposing Factors:    Wide variety of microbes in hospital environment Weakened or immunocompromised patients Chain of transmission: Mainly through direct or indirect contact. • • • • From health care workers to patient From patient to patient Fomites: Catheters, needles, dressings, beds, wheelchairs Airborne transmission
  • 24. Important Nosocomial Pathogens Normal microbiota: Many are opportunistic pathogens Antibiotic resistance: Very high due to the use of antimicrobials in health care facilities. Principle microorganisms: Used to be gram-positive microbes. Today most are gram-negative bacteria.      Enterobacteria: Over 40% of all infections. E. coli, Klebsiella spp., Proteus spp., Enterobacter spp., and Serratia marcescens. Staphylococcus aureus (11%) Fungi: (10%) C. albicans and others Enterococcus (10%) Pseudomonas aeruginosa (9%)
  • 25. Control of Nosocomial Infections Aseptic techniques to avoid contamination Careful handling and disposal of contaminated material Frequent and adequate hand washing Proper infection control training of staff Isolation wards and rooms Avoid unnecessary antibiotic prescriptions Avoid unnecessary invasive procedures Regular disinfection of respirators and humidifiers and maintenance of autoclaves Use disposable and/or sterile supplies Infection control committee
  • 26. Development of Disease 1. Incubation Period: Time between initial infection and appearance of signs and symptoms 2. Prodromal Period: Early, mild symptoms of disease. 3. Illness Period: Disease is most acute. Overt signs and symptoms. Patient immune system actively fights off infection. If not successful may die at this stage. 4. Decline Period: Signs and symptoms subside. Patient is vulnerable to secondary infections. 5. Convalescence Period: Recovery. Body returns to predisease state.
  • 27. Immunity in the oral cavity Non specific immunity -intact mucosal barrier -dental arches position -saliva -lysozyme -peroxidase -lactoferrin Specific immune response -tissues -immunoglobulins and other soluble mediators
  • 28. Development of the oral flora Birth – sterile….. - strep.salivarius, Nesseria, veillonella - occasionally C.albicans….. Infancy & early childhood eruption of deciduous teeth appearance of strep. Sanguis & mutans Increasing no. of teeth and changes in diet….. Few anaerobic become established…….
  • 29. Development of oral flora contd Adolescence increase in no. of organisms occurs when permanent teeth erupt They have deep fissures, interproximal surfaces are larger, gingival crevice is deeper---- increase in anaerobic organisms Bacteroides, leptotrichia, fusobacterium, spirochaetes are found regularly Lesions of dental caries………..
  • 30. Development of oral flora contd Adulthood complexity is its characteristic -Varying amounts of dp,chronic pdl disease, govern the no. and type of organisms… carious lesions, unsatisfactory restorations provides environments for accumalations of bacteria -Increase in bacteriodes and spirochaetes -As teeth are lost…….. -Edentulous pts. harbour few spirochaetes or bacteroides. Carriage of yeasts increases -Dentures provide a protected environment in which yeasts multiply…
  • 31. Factors affecting the development of the oral flora Be introduced Be retained Be able to multiply in the conditions present in the mouth
  • 32. Factors affecting the development of the oral flora contd.. Introduction - although from birth a wide variety of microorganisms are introduced into mouth, only certain species are able to become established Retention - adherence eg.strep.salivarius - protected sites Sticky matrix of dental plaque and gingival crevices bact.melaninogenicus and spirochates
  • 33. Multiplication Factors governing are - availability of substrates * increased carbohydrate in the diet, increases the no. of oral bacteria - ph * bact. Melaninogenicus, veillonella are intolerent of ph below 5.5 * lactobacillus and C.albicans can tolerate very low ph values - oxidation/reduction of the surroundings * anaerobic organisms such as bacteroides, fusobacterium, spirochaetes, actinomyces only multiply in reduced surroundings. * gingival crevice and deeper layer of dental plaque are the areas with low oxidation/reduction potential
  • 34. Multiplication contd Microbial interactions Some of the interactions are nutritional such as provision of PABA by strep.sanguis for strep.mutans in reduced conditions. The provision of vitamin k by several microorganisms for bact.melaninogenicus Some of the interactions are detrimental rather than beneficial to a second species eg. Production of H2 O2 by strep.sanguis inhibit many other streptococci and anaerobes
  • 35. The normal microbial flora of different sites of the mouth Lips staph.albus and skin micro-cocci predominate with large no. of streptococci typical of mouth Cheeks predominant bacterium is strep.mitior with strep.sanguis and salivarius yeasts may isolated from carriers Palate streptococcal flora resembling cheek haemophili, lactobacilli are common yeasts and lactobacilli in denture wearers because of protected enviornment Tongue dorsal surface of the tongue is the ideal surface for retention of microorganisms predominant organisms- strep.salivarius, strep.mitior, haemophilus, small no. of C.albicans micrococcus mucilageneous……..
  • 36. The normal microbial flora of different sites of the mouth contd Gingival crevices -most numerous of any site in the mouth. -1010- 1011 organisms per gr. Wet wt. Of gingival debris -well protected from forces that dislodge bacteria -facultative gr+ve cocci 27, anaerobic gr+ve & gr-ve rods/filaments 40% Teeth # organisms attach through dental plaque # build up as follows - occlusal fissures and pits - in enamel defects - in interproximal spaces - close to gingival margins Saliva # microbial count of saliva 107- 108 org/ml # for many years regarded as representative of oral flora….
  • 37. Dentures and other intra oral appliances Any appliance worn for considerable period, become colonized with microorganisms and may alter the flora Fixed appliances supports supra gingival plaque if poorly constructed Removable appliances have advantage of being able to be cleansed properly… Yeasts & lactobacilli multiply on any mucosal surface protected from the flow of saliva Acrylic appliances retain a denser flora than metal…. large no. of C.albicans can be cultured from the fitting surfaces of the acrylic dentures.
  • 38. The principal microorganisms of the mouth Cocci Gr+ve strep.sanguis strep.mutans strep.mitior strep.salivarius strep.milleri Gr-ve neisseria veillonella Rods/filaments Gr+ve lactobacillus corynebacterium actinomyces eubacterium arachnia propionibacterium Gr-ve haemophilus eikenella campylobacter bacteroides fusobacterium actinobacillus capnocytophaga wolinella
  • 39. The principal microorganisms of the mouth contd Anaerobic bacteria- spirochaetes Yeasts- C.albicans, tropicalis, krusei Mycoplasma- M.orale, salivarium, faucium, buccale Protozoa- Entamoeba gingivalis, trichomonas tenax viruses
  • 40. Dental plaque Dental plaque is defined as soft deposits that form the biofilm adhering to the tooth surface or other hard surfaces in the oral cavity, including removable and fixed restoration Dp is composed primarily of microorganisms 1gm plaque(wet wt) contains 2*1011 bacteria Meteria alba.. Plaque formation -formation of pellicle coating -initial colonization by bacteria Gr+ bacteria, act.viscous. Strep.sanguis & other streptoocci,vellonella,corynebacterium -secondary colonization and plaque maturation Grbacteria, P.intermedia, P.loscheii, capnocytophaga, fusobacteriu
  • 41. Microbial interactions in DP Benificial or detrimental Strep.mutans, sanguis & lactobacilli lowers the ph by the fermentation of the carbohydrates to produce an environment unsuitable for other organisms like veillonella, bacteriodes Hydrogen peroxide produced by strep.mutans inhibits actinomcetes & a wide range of other microorganisms Vitamin k produced by corynebacterium stimulate the growth of bact.melaninogenicus
  • 42. calculus Produced by calcification of supra & subgingival dental plaque Hardness varies as the deposition of calcium phosphate occurs in patches Local ph changes, saliva with super saturated solution of calcium and phosphate provides enviornment for plaque calcification Bacterionema matruchoti along with veillonella, nesseria, Haemophilus & bacteroides plays imp role…….
  • 43. Control of dental plaque Diet Physical removal Ultrasonic scaling devices Antiseptics Antibiotics
  • 44. Dental Caries Odontopathic Bacteria Mutans group of Streptococci Initiator of Caries Lactobacillus (acid-loving bacteria) Secondary invader
  • 45. CARIOGENIC DENTAL PLAQUE Bacteria produce a strong acid - Lactic Acid Bacteria produce surface molecules which seal the acid against the tooth and keep the saliva from buffering the Lactic Acid Bacteria are capable of continually producing the Lactic Acid due to stores of glycogen within the bacterial cells Streptococcus mutans Early colonizer of the tooth Strong Protease Producer Removes the salivary coat from its surface Binds to Salivary coated tooth surfaces (only after removing the coat of saliva on its surface)
  • 46. LACTOBACILLUS Acidophilic (acid-loving) environments (Inside Deep Carious Lesions) { pH = 5.3 4.5 pH = 4.5 3.7 { LACTOBACILLU S
  • 47. Dental caries Microbiological aspect of caries prevention diet plaque control immunisation against dental caries based on belief that most carious lesions are initiated by strep.mutans vaccine to stimulate production of antibodies to organism, which can then reach the site where caries is likely to develop and so exert a protective effect
  • 48. Periodontal disease Acute ANUG periodontal abscess Chronic gingivitis periodontitis juvenile periodontitis
  • 49. Periodontal disease contd ANUG Characterized by the destruction of interdental papillae and often gingival margin Isolated organisms are Borrella vincenti fusobacterium fusiforme bact.melaninogenicus Treatment careful oral hygiene measures metronidazole Periodontal abscess organisms isolated Bact.gingivalis Anaerobic cocci, Facultative cocci, actinomyces
  • 50. Periodontal disease contd Gingivitis Inflammation of gingivae appears to be caused by bacteria and their products in dental plaque to gingival margin Acute inflammatory response with dilatation of gingival capillaries and exudaation of fluid containing IgG, complement,and PMN’s No particular organism have been implicated…. Removal of dp… Act.viscosus/naeslundi
  • 51. Periodontal disease contd chronic periodontitis Gingivitis if not controlled leads to periodontitis Attachment of junctional epithelium to the tooth migrates apically and gingival pocket forms This deepened pocket is colonised by dp bacteria and so a progressive deepening of the pocket ensues In the advance lesion the chronic inflammatory response leads to destruction of collagen ane bone supporting the tooth. Organisms isolated anaerobic especially bact.gingivalis, eikenella corrodens,spirochaetes, bact.melaninogenicus, act.viscous/naeslundi, act.israell i, veillonella Treatment control of plaque elimination of pockets that cannot be kept clean antibiotics have no role
  • 52. Juvenile periodontitis Some young patients develop a degree of pdl destruction well in advance of that expected for their age Two organisms predominate -actinobacillus actinomycetem comitans -capnocytophaga Both organisms appear to promote the destruction of fibroblasts and activity of osteoclasts
  • 53. Bacterial infections of oral cavity Syphilis Actinomycoses Tuberculosis Diphteria Scarlet fever Leprosy Tetanus
  • 54. Candidiasis (oral thrush) Caused by candida albicans Common inhabitant of oral cavity Most opportunistic infection in world Causes- inadverent use of antibiotics, immunosupressive drugs Eg. Corticosteroids, cytotoxic drugs C/F – soft, white, slightly elavated plaque on buccal mucosa, tongue. plaque can be wiped away with gauze leaving erythematous area AIDS patients suffer andrugs nystatin, chlortrimazoles, amphotericin Rx – antifungal intractable form of oral thrush, caused by a newlydescribed species, Candida dubliniensis. This organism is more resistant to B, Iconozole antifungal therapy than Candida albicans. AIDS patients may also present with Kaposi sarcoma tumours in the oral cavity.
  • 55. Types of Candidiasis Pseudomembranous candidiasis Thrush Hyperplastic candidiasis Atrophic candidiasis
  • 56. Viral infections of oral soft tissues HSV-1 and/or HSV-2 Primary Infection Secondary Infection Varicella zoster virus (HHV-3) Herpesvirus Infection Primary Infection Herpetic gingivostomatitis Younger patients Often asymptomatic May be associated with fever, chills, malaise Vesicles-ulcers-crusting Anywhere in the oral cavity
  • 57. Herpesvirus Infection Secondary Infection Reactivation of latent virus Not associated with systemic symptoms Small vesicles Occur only on the hard palate and gingiva Prodromal signs Varicella zoster virus
  • 58. Herpangina NOT caused by Herpesvirus Coxsackie A virus Children < 10 years of age Common in summer and fall Often subclinical presentation Headache/Abdominal pain 48hrs prior to papulovesicular lesions on tonsils and uvula. Sore throat
  • 59. Why Is Infection Control Important in Dentistry? Both patients and dental health care personnel (DHCP) can be exposed to pathogens Contact with blood, oral and respiratory secretions, and contaminated equipment occurs Proper procedures can prevent transmission of infections among patients and DHCP
  • 60. Modes of Transmission Direct contact with blood or body fluids Indirect contact with a contaminated instrument or surface Contact of mucosa of the eyes, nose, or mouth with droplets or spatter Inhalation of airborne microorganisms
  • 61. Standard Precautions Apply to all patients •Elements of Standard Precautions Handwashing Use of gloves, masks, eye protection, and gowns Patient care equipment Environmental surfaces Injury prevention
  • 62. Personal Protective Equipment ,
  • 63. Sterilization and Disinfection of Patient Care Items Critical Instruments Penetrate mucous membranes or contact bone, the bloodstream, or other normally sterile tissues (of the mouth) Heat sterilize between uses or use sterile single-use, disposable devices Examples include surgical instruments, scalpel blades, periodontal scalers, and surgical dental burs •Semi-critical Instruments Contact mucous membranes but do not penetrate soft tissue Heat sterilize or high-level disinfect Examples: Dental mouth mirrors, amalgam condensers, and dental handpieces
  • 64. Noncritical Instruments and Devices Contact intact skin Clean and disinfect using a low to intermediate level disinfectant Examples: X-ray heads, facebows, pulse oximeter, blood pressure cuff •Saliva Ejectors Previously suctioned fluids might be retracted into the patient’s mouth when a seal is created Do not advise patients to close their lips tightly around the tip of the saliva ejector
  • 65. Preprocedural Mouth Rinses Antimicrobial mouth rinses prior to a dental procedure Reduce number of microorganisms in aerosols/spatter Decrease the number of microorganisms introduced into the bloodstream Oral Surgical Procedures Present a risk for microorganisms to enter the body Involve the incision, excision, or reflection of tissue that exposes normally sterile areas of the oral cavity Examples include biopsy, periodontal surgery, implant surgery, apical surgery, and surgical extractions of teeth
  • 66. Extracted Teeth Considered regulated medical waste Do not incinerate extracted teeth containing amalgam Clean and disinfect before sending to lab for shade comparison Can be given back to patient Handling Extracted Teeth in Educational Settings Remove visible blood and debris Maintain hydration Autoclave (teeth with no amalgam)
  • 67. Automated Cleaning Ultrasonic cleaner Instrument washer Washer-disinfector Manual Cleaning Soak until ready to clean Wear heavy-duty utility gloves, mask, eyewear, and protective clothing
  • 68. Heat-Based Sterilization Steam under pressure (autoclaving) Dry heat Unsaturated chemical vapor Liquid Chemical Sterilant/Disinfectants Only for heat-sensitive instruments Powerful, concerns toxic chemicals raise safety Heat tolerant or disposable alternatives are available
  • 69. Disinfectants Disinfectants are chemicals that destroy or inactivate most species of pathogenic (disease-causing) microorganisms. In dentistry, only those products that are Environmental Protection Agency (EPA)-registered hospital disinfectants with tuberculocidal claims (kills the tuberculosis bacteria) should be used to disinfect dental treatment areas. The Mycobacterium tuberculosis is highly resistant to disinfectants, and if a disinfectant will inactivate the M. tuberculosis, it will most certainly inactivate the less resistant microbial families (such as bacteria, viruses, and most fungi) on the treated surface.
  • 70. Environmental Surfaces May become contaminated Not directly involved in infectious disease transmission Do not require as stringent decontamination procedures Clinical contact surfaces High potential for direct contamination from spray or spatter or by contact with DHCP’s gloved hand Housekeeping surfaces Do not come into contact with patients or devices Limited risk of disease transmission
  • 71. Clinical Contact Surfaces
  • 72. Housekeeping Surfaces
  • 73. Cleaning Clinical Contact Surfaces Risk of transmitting infections greater than for housekeeping surfaces Surface barriers can be used and changed between patients OR Clean then disinfect using an low- (HIV/HBV claim) to intermediate-level (tuberculocidal claim) hospital disinfectant Cleaning Housekeeping Surfaces Routinely clean with soap and water or an detergent/hospital disinfectant routinely Clean mops and cloths and allow to dry thoroughly before re-using Prepare fresh cleaning and disinfecting solutions daily and per manufacturer recommendations
  • 74. Infection control in dental laboratory Potential for disease transmission in the dental lab is well documented Potential pathogens can be transported to lab via orally soiled impressions, dental prostheses/appliances Microorganisms can be transferred from contaminated impressions to dental casts Oral bacteria can remain viable in set gypsum for up to 7 days BASICS OF LABORATORY IC Need coordination between dental office and lab Use of proper methods/materials for handling and decontaminating soiled incoming items All contaminated incoming items should be cleaned and disinfected before being handled by lab personnel, and before being returned to the patient
  • 75. MASK/PROTECTIVE EYEWEAR/CLOTHING Must be used when there is potential for splashes, spray, spatter, or aerosols Examples: when operating lathes, model trimmers, and other rotary equipment Lab coat/jacket should be worn at all times during fabrication process Change daily Do not wear outside of the lab Launder appropriately
  • 76. IMPRESSIONS Many studies have been performed to evaluate effects of various disinfectants on different types of impression materials Research findings have been contradictory No single disinfectant is compatible with all impression materials The least distortion is associated with products having the shortest contact times
  • 77. IMPRESSIONS Many variables can affect impression materials Composition and concentration of disinfectants Exposure time and compatibility of various disinfectants with specific impression materials Physical/chemical properties can vary in a given category of material or disinfectant Consult dental materials’ manufacturers regarding their compatibility with disinfectants
  • 78. DISINFECTING IMPRESSIONS Methods Spraying, immersing Exposure time should be that recommended by the manufacturer of disinfectant for tuberculocidal disinfection Iodophors, sodium hypochlorite (1:10 concentration), chlorine dioxide, phenols, and other approved products are all acceptable
  • 79. DISINFECTING IMPRESSIONS Polyether materials cannot be immersed in disinfectants due to potential for absorption and distortion Immersion disinfectants can only be used once before discarding (except for glutaraldehydes) Most reports indicate dimensional stability is not significantly affected by immersion technique Clean and rinse impression in dental operatory Cleaning efficiency can be improved by gently scrubbing impression with camel’s hair brush and antimicrobial detergent  Sprinkle dental stone into impression before rinsing to aid in cleaning Cleaning and rinsing  Reduces bioburden present  Lessens overall microbiologic challenge to disinfectant
  • 80. DENTAL CASTS Very difficult to disinfect It Is preferable to disinfect impression If casts must be disinfected: Place casts on end to facilitate drainage Spray with iodophor or chlorine product, then rinse Another option Soak casts for 30 minutes in 0.5% concentration of sodium hypochlorite and saturated calcium dihydrate solution (SDS) SDS is produced by placing uncontaminated, set gypsum (i.e. stone) in a container of water
  • 81. ORALLY SOILED PROSTHESES Scrub with brush and antimicrobial soap to remove debris and contamination Can be accomplished in operatory or professional work area Sterilize brush or store in approved disinfectant Place prosthesis in sealable plastic bag or beaker filled with ultrasonic cleaning solution or calculus remover Place in ultrasonic cleaner for required time as specified by manufacturer of ultrasonic cleaner Place cover on ultrasonic cleaner to reduce spatter potential Remove and rinse under running tap water, dry, and accomplish required work
  • 82. LATHE Ways to reduce risk of injury from aerosols, spatter, and macroscopic particles Use protective eyewear Ensure plexiglass shield is in position 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. Change pumice daily
  • 83. IMPRESSION TRAYS Precleaning removes bioburden and any adherent impression material Ultrasonic cleaning can aid in removing residual set gypsum Chrome-plated or aluminum trays Clean, package, heat sterilize Single-use trays Discard after one use Custom acrylic trays Can be disinfected (by spray or immersion), then rinsed (if to be used for second appointment)
  • 84. DISINFECTION Prosthodontic items contaminated by handling should be disinfected (by spray or immersion technique based on type of item) after each use Examples: alcohol torch, facebow, articulator, mixing spatula, mixing bowl, lab knife, shade/mold guide WAX BITES/RIMS, BITE REGISTRATIONS Immersion disinfection may cause distortion to some items  Use spray disinfection Heavy-body bite registration materials Usually not susceptible to distortion and can be disinfected in same manner as an impression of the same material 
  • 85. PERSONAL HYGIENE Refrain from the following activities while in the lab where there is potential for occupational exposure: Eating Drinking Smoking Applying cosmetics or lip balm Handling contact lenses
  • 86. conclusion Very few microbes are always pathogenic Many microbes are potentially pathogenic Most microbes are never pathogenic
  • 87. References Text book of microbiology; 5th edition: ananthnarayan Medical bacteriology; key and key Oral microbiology & immunology; Micheal G Newmann Microbiology in clinical dentistry; Frank J Orland Clinical & oral microbiology; PW Ross Clinical periodontology- Carranza J periodontology 1971;42:485-94 Oral pathology: Shafer Control of infection guidelines; 2 nd edition:NHS
  • 88. Thank you For more details please visit