Dental caries is a disease of dental hard tissues caused by the interaction of host, micro-organisms, environment and most essentially time. Several methods have been introduced in the past for diagnosing caries but the one of the most important tasks in the modern concept of dentistry is the early detection and treatment of an initial carious lesion. This new notion has given rise to a number of procedures that has substituted the original concept of Black’s of “extension for prevention” to minimally invasive techniques and to the more recent “ozone therapy” which aims at eliminating only the infected and demineralised dental tissue and hence conserves and protects the tooth structure. Bactericide and disinfection properties of ozone enabled a new concept of “painless therapy” in treatment of caries lesions1.
C.D. Schonbein, german chemist first discovered ozone while the first medical application was in 1870 when Dr. C. Lender purified blood in test tubes. It was in 1930 when Dr. E.A. Fisch used ozone on a regular basis in his dental practice.
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Ozone (O3) is naturally produced by the photo dissociation of molecular Oxygen into activated oxygen atoms, which then react with further oxygen molecules. This transient radical anion rapidly becomes protonated, which in turn decomposes to an even more powerful oxidant, the hydroxyl radical (OH-).
The effects or ozone on microorganisms is well documented2 .For some time it has been used in medicine for the treatment of rheumatic and skin diseases, but recently it is applied in dentistry also Ozone has a virulent, bactericidal and fungicidal action. Research has shown that ozone disrupts the cell walls of micro-organisms within seconds, leading to immediate death. The effect on fungi is very similar, and viruses are inactivated. Its purpose is to enable healing of caries affected tissue using biologically active substances. This mode of action effectively destroys the caries causing bacteria inside as well as on the surface of the tooth and the high disinfectant action enables healing.
O3 can also attack many biomolecules such as the cysteine, methionine and the histidine residues of proteins and change the surface ecology of the carious lesion3.
Forms of application of ozone to oral tissues are ozonated water, ozonated olive oil and oxygen/ozone gas.
Uses of ozone in Dentistry
In case of irregularities in the mineralization of hard dental tissue, use of ozone can be very beneficial because such areas are more for colonisation of S. mutans (i.e. fluorosis). In the case of tetracycline defects, the effect of ozone is low because the enamel surface is intact.
The fissure system is an ideal place for sedimentation of S. mutans. Ozone application before sealant greatly benefits removal of bacteria from plaque in a deep fissure, which prevents occurrence of caries beneath sealing materials.
Restorative procedures in children are often difficult especially when the children are uncooperative. If that is the case, ozone application presents a non-invasive and painless alternative. In some cases, the fissure system is treated with glass ionomer cements that release fluorides with depoeffect and induce remineralization.
Bottle caries is caused by the constant use of the bottle. Ozone therapy can be implemented to stop further growth of an already formed lesion and avoid classical caries sanation, which can be quite difficult at such an early age1.
Exposed root surfaces in aged individuals with gingival recession are more susceptible to caries Treatment of the root caries may be achieved by increasing the resistance of the lesion and reducing the extent of microbial activity. Hence treatment of root caries may be achieved without placing the restorative materials but by applying an effective level of ozone3.
Reversal of primary root caries lesions is associated with remineralization and a corresponding reduction in acidogenic and aciduric micro-organisms4.
Recently, a new device Heal Ozone (KaVo Dental GmbH, Germany) was introduced in the market which offers a new, non-traumatic concept in the treatment of caries lesions. It consists of a generator, ozone, vacuum pump, unit for neutralization and a rubber hose with a hand piece on which silicone caps are applied. The silicone cap is placed on the caries affected tooth enabling the creation of an impermeable layer or the so called vacuum effect.
Research by Baysan showed that5
• Treatment with Heal Ozone 10 sec eliminates 99% bacteria
• Treatment with Heal Ozone 20 sec eliminates 99.9% bacteria
• In most cases of root caries and caries in fissures remineralization occurs within 4-12 weeks

It has also been showed that ozonated water(0.5-4mg/l) is highly effective in killing both gram positive and gram negative oral micro-organisms. Among them, the gram negative bacteria like the P. Endodontalis, and P. Gingivalis are more sensitive than the gram positive bacteria and C. Albicans. Also it was found that ozonated water had strong bactericidal activity against the bacteria in plaque biofilm. In addition, ozonated water inhibited the accumulation of experimental dental plaque in vitro6.

Summary:
Modern dentistry needs to take a biological approach to the management of dental caries, where the emphasis must be on diagnosing the oral ecological balance and effecting biological change in the oral biofilm. With the advent of several new restorative materials as well as new technologies such as ozone, it is now possible to disinfect the carious cavities and promote remineralization and promote the revolutionary concept of minimally invasive dentistry.
References
1. Knezevic A, Tarle Z, Prskalo K. Ozone treatment of initial lesions. Acta Stomat Croat 2004; 371-374.
2. Beighton D, Lynch E, Heath MR. A microbiological study of primary root caries lesions with different treatment needs. J Dent Res 1993;73:623-629.
3. Brostek AM, Brochenek AJ, Walsh LJ. Minimal invasive operative techniques using high tech dentistry. Dental practice 2006: 106-108.
4. Lynch E. The diagnosis and management of primary root caries. PhD thesis. London: University of London, 1994.
5. Baysan A. Management of primary root caries using ozone therapies. PhD thesis, University of London, 2002.
6. Nagayoshi M, Fukuizumi T, Kitamura C, Yano J, Terashita M, Nishihara T. efficacy of ozone on survival and permeability of oral microorganisms. Oral Microbiology Immunology 2004;19 : 240-246.

Dr. Vivek K Adlakha, Dr. Deepika Jauhari SUBHARTI DENTAL COLLEGE, MEERUT