**1. Introduction**

332 Antimicrobial Agents

Vujić, J.M., Garcia-Granda, S., Menendez-Taboada, L. & Trifunović, S.R. (2011). Crystal

2-4, 2011.

structure of palladium(II) complex with *O,O'*- dipentil-etilenediamine- *N,N'*-di- (*S,S*)-2(4-methy)-pentanoate ligand. *Proceedings of XVIII Conference of the Serbian Crystallographic Society*, pp. 40, ISBN: 978-86-7031-194-7, Fruška Gora, Serbia, June

> Because progressive increase in serious transmissible diseases over the last few decades, every health care specialty that involves contact with mucosa, blood or blood contamination, like dentistry, should regulate regarding sterilization and disinfection. Dental patients and dental health-care workers may be exposed to a variety of microorganisms via blood or oral or respiratory secretions. These microorganisms may include cytomegalovirus, *hepatitis B virus (HBV), hepatitis C virus (HCV), herpes simplex virus types 1* and *2, human immunodeficiency virus (HIV), Mycobacterium tuberculosis, staphylococci, streptococci*, and other viruses and bacteria; specifically, those that infect the upper respiratory tract (Blently, 1994). Infections may be transmitted in the dental operatory through several routes, including direct contact with blood, oral fluids or other secretions; indirect contact with contaminated instruments, operatory equipment or environmental surfaces or contact with airborne contaminants present in either droplet spatter or aerosols of oral and respiratory fluids. Infection via any of these routes requires that all three of the following conditions be present (commonly referred to as "the chain of infection": a susceptible host; a pathogen with sufficient infectivity, numbers to cause infection and a portal through which the pathogen may enter the host) (Burkhart, 1970). Effective infectioncontrol strategies are intended to break one or more of these "links" in the chain, thereby preventing infection. A set of infection-control strategies common to all health-care delivery settings should reduce the risk of transmission of infectious diseases caused by blood-borne pathogens such as *HBV* and *HIV*. Because all infected patients cannot be identified by medical history, physical examination, or laboratory tests, it is recommended that blood and body fluid precautions be used consistently for all patients. In dentistry, beside personal protections like eyewear, gloves and gowns, pretreatment mouth rinse, rubber dam and high velocity air evacuation are the other considerations regarding infection control (Hackney, 1989). Suitable sterilization and disinfection of instruments are inseparable parts of infection control puzzle. So, discussion about the techniques and agents used in sterilization and disinfection is very important, nowadays. In this chapter we mention the antibacterial agents used in sterilization and disinfection in dentistry.

<sup>\*</sup> Corresponding Author

Antibacterial Agents in Dental Treatments 335

It should be mentioned that the efficacy of disinfectant depends on contact time, temperature, type and concentration of the active ingredient, the presence of organic matter,

The action mechanisms of this subgroup of disinfectant are coagulation of protein, dehydration of cells and disruption of membranes (Moorer, 2003). Alcohols, usually ethanol or isopropanol, are sometimes used as a disinfectant, but more often as an antiseptic. A 70% aqueous solution is more effective at killing microbes than absolute alcohols. Because water facilitates diffusion through the cell membrane; 100% alcohol typically denatures only external membrane proteins. A mixture of 70% ethanol or isopropanol diluted in water is effective against a wide spectrum of bacteria, though higher concentrations are often needed to disinfect wet surfaces (Brent, 2009). Additionally, high-concentration mixtures (such as 80% ethanol + 5% isopropanol) are required to effectively inactivate lipid-enveloped viruses (such as *HIV, hepatitis B, and hepatitis C*). 70% ethyl alcohol is used as antiseptic on skin. Isopropyl alcohol is preferred to ethanol. It can also be used to disinfect surfaces. It is used to disinfect clinical thermometers. Methyl alcohol kills fungal spores, hence is useful in disinfecting inoculation hoods (Engelenburg, 2002). Alcohols have some disadvantages. They can be a fire hazard. Also, they have limited residual activity due to evaporation, which results in brief contact times unless the surface is submerged, and have a limited activity in the presence of organic material. They are skin irritants and inflammable

The other subgroup of disinfectants is aldehydes that act through alkylation of amino, carboxyl-or hydroxyl group, and probably damage nucleic acids. They have a wide microbiocidal activity and are sporocidal and fungicidal (Crawford, 1983). The most popular of this subgroup are formaldehyde and gluteraldehyde. 40% formaldehyde (formalin) is used for surface disinfection. 10% formalin with 0.5% tetraborate sterilizes clean metal instruments. 2% gluteraldehyde is used to sterilize thermometers, cystoscopes, bronchoscopes, centrifuges, anasethetic equipments etc. An exposure of at least 3 hours at alkaline pH is required for action by gluteraldehyde. 2% formaldehyde at 40oC for 20 minutes is used to disinfect wool and 0.25% at 60oC for six hours to disinfect animal hair and bristles (Favero&Bond, 1991). Disadvantages of these agents are: Vapors are irritating and must be neutralized by ammonia, have poor penetration, leave non-volatile residue, activity is reduced in the presence of protein. Some bacteria have developed resistance to glutaraldehyde, and it has been found that glutaraldehyde can cause asthma and other health hazards; hence ortho-phthalaldehyde is replacing glutaraldehyde (Crawford, 1983).

Halogens for example Chlorine compounds (chlorine, bleach, hypochlorite) and iodine compounds (tincture iodine,iodophores) are oxidizing agents and cause damage by oxidation of essential sulfydryl groups of enzymes. Chlorine reacts with water to form hypochlorous acid, which is microbicidal. Applications of this group are: Tincture of iodine (2% iodine in 70% alcohol) is an antiseptic (Crawford, 1983). Iodine can be combined with

the type and quantum of microbial load.

**2.1 Alcohols** 

(Lodgsdon, 1994).

**2.2 Aldehydes** 

**2.3 Halogens** 
