Introduction

The word ozone is derived from the greek word ozein (odorant). Ozone is the most powerful antimicrobial agent, which is used in both medicine and dentistry. Dr.Edwin Parr (Swiss dentist) started to use O₃ as a part of disinfection system. Ozone is a chemical compound consisting of three atoms of oxygen. It is the elemental form of oxygen that occurs naturally as a result of ultraviolet energy or lightning, causing a temporary recombination of oxygen atoms into groups of three. It protects living organisms by surrounding the earth at altitudes of 50,000 to 100,000 feet from the ultra-violet rays. As it falls downward to earth, being heavier than air, and combines with any pollutant it comes in contact, and cleans the air. This is Mother Earth’s natural way of self-cleaning. In the clinical setting, an oxygen/ ozone generator simulates lightning via an electrical discharge field. Ozone is a powerful oxidizer it effectively kills bacteria, fungi, viruses, and parasites at a dramatically lower concentration than chlorine. One molecule of ozone is equal to between 3,000 to 10,000 molecules of chlorine and it kills pathogenic organisms 3,500 times faster.

Ozone is an unstable gas and it quickly gives up nascent oxygen molecule to form oxygen gas. The release of nascent oxygen has beneficial effects on every part and organ. It has been used in medical field since long due to its extremely strong oxidative property that oxidizes nearly all surfaces to the highest oxidation stage. It is used as a circulatory enhancement and stimulation of oxygen metabolism, disruption of tumor metabolism and to kill pathogens. Ozone is a powerful oxidant capable of interacting as metabolic & immune modulator as well as anti-microbial agent. Among other things, ozone is used to purify drinking water and water in dental equipment and for sterilizing instruments for medical use.

In oxygen/ ozone therapy in dentistry, our goals are:

Elimination of pathogens

Restoration of proper oxygen metabolism

Induction of a friendly ecologic environment

Increased circulation

Immune activation

Simulation of the humoral anti-oxidant system

History

The German chemist Christian Friedrich Schonbein (1840), of the University of Basel in Switzerland is regarded as the Father of ozone therapy. When he passed an electrical discharge through water, a distinct odour was produced, which he called Ozone, derived from the Greek word ozein which means odour. In 1857 Joachim Hansler, a German physicist and physician, along with German physician, Hans Wolff, developed the first ozone generator for medical use. Dr. C. Lender in1870, for the first time applied ozone into medical field. He purified blood in test tubes by using ozone. In World War I and II it was used to treat wounded soldiers in the trenches. In early 20th century Food and Drug Act, revised its use and effect in the field of medicine. They considered it as perfectly legal to use in US. Since then, it was used in the treatment of deadly diseases such as tuberculosis, pneumonia, diabetes . It was also used to cure wounds, gangrene and the effects of poisonous gas. German dentist, Dr. E.A. Fisch, in 1950 was the first dentist to use ozone on a regular basis in his clinical practice in Zurich, Switzerland and published numerous papers on its application.

Production of Ozone Gas 

Ozone is created when an oxygen molecule receives an electrical discharge following thunder storm breaking it into two oxygen atoms. The individual oxygen atoms combine with another oxygen molecule to form O₃

Ultraviolet rays emitted from the sun plays the role of electrical discharge over oxygen present in the stratosphere thus, creating the ozone layer which absorbs most of the ultraviolet radiation emitted by the sun.

In the clinical setting, an ozone generator stimulates lightning via an electrical discharge field.

Generation of Ozone Gas in Dentistry

 Ultraviolet system

Produces low concentrations of ozone, used in aesthetics and for air purification.

Cold plasma system

Used in air and water purification.

Corona discharge system

Produces high concentrations of ozone. It is the most common system used in the medical/ dental field. It is easy to handle and it has a controlled ozone production rate.

Routes of Ozone Administration:

Oxygen/ozone therapy in dentistry contains a multiplicity of protocols to deal with dental infection. Three basic forms of application to oral tissue are applied – 1) Ozonated water, 2) Ozonated olive oil, and 3) Oxygen/Ozone gas.

Gaseous Ozone

Gaseous ozone is most frequently used in restorative dentistry and endodontics. Topical administration of the gaseous form can be via an open system or via a sealing suction system as a prerequisite to avoid inhalation and adverse effects. Ozone appears to be an integral part of non-invasive therapy of dental caries, as a disinfectant prior to placing a direct restoration and as therapy for hypomineralized teeth. ⁶

Ozonated Water

Ozonated water has been shown to be very effective against bacteria, fungi and viruses and is also less expensive compared to other chemical cleaners. Gaseous ozone was shown to be a more effective microbicide than the aqueous form and, applied for 3 min, may be used as a dental disinfectant. Because ozone gas has been found to have toxic effects if inhaled into the respiratory tract, ozonated water may be useful to control oral infections and various pathogens.^6,7,8

Ozonized Oil

In addition to ozone application in its gaseous and aqueous form, sunflower ozonized oil also seems extremely convenient. The wide accessibility of sunflower oil makes it a competitive antimicrobial agent. Ozonized oil (Oleozone, Bioperoxoil) has shown to be effective against Staphylococci, Streptococci, Enterococci, Pseudomonas, Escherichia coli and especially Mycobacteria and has been utilized for the cure of fungal infections. ^6,9,10

Antimicrobial Action of Ozone

Ozone in the gaseous or aqueous phase has been shown to be a powerful and reliable antimicrobial agent against bacteria, fungi, protozoa and viruses. It is generally accepted that the oxidant potential of ozone induces the destruction of cell walls and cytoplasmic membranes of bacteria and fungi. During this process, ozone attacks the glycoproteins, glycolipids and other amino acids, inhibits and blocks the enzymatic control system of the cell. This results in increase in membrane permeability, the key element of cell viability, leading to immediate functional cessation. Then ozone molecules can readily enter the cell and cause the microorganism to die.⁴

Immunostimulating Action of Ozone

Activates cellular and humoral immune system

Proliferation of immunocompliment cells

Synthesis of immunoglobulins

Enhance phagocytosis activity

Activation of biological antioxidants

Disruptive Action of Cariogenic Bacteria

Ozone can attack many biomolecules, such as the cysteine, methionine and histidine residues of proteins. By oxidizing the biomolecules featured in the dental tissues, ozone has severely disruptive effect on cariogenic bacteria, resulting in the elimination of acidogenic bacteria. The strongest naturally occuring acid produced by acidogenic bacteria during cariogenesis is pyruvic acid. Ozone can decarboxylate this acid to acetic acid. It has been shown that remineralization of incipient carious lesions can be encouraged when the production of acetic acid or other high pKa acids found in resting plaque, buffers plaque fluid.

Indications of Ozone Therapy in Dentistry:

Oral Medicine

Soft tissue lesions like Herpes, Aphthae, Removable denture ulcers, Cuts, Cheilitis, Candidiasis, Cysts and Traumatic wounds can be treated with either Ozonated water or oils.¹¹

Oral Surgery

After a tooth is extracted or any basic surgical procedure it is recommended post‐surgically to irrigate and insufflate the area. This reduces the positive electric potential of the wound and potential scar with the negatively charged gas or water. Healing of the wound is generally much faster and with less or no complications. Biphosphonate necrosis has been extremely difficult to treat medically and surgically. There has been some success with ozone utilizing the foundational protocols along with intraosseous injections and intraoral silicone tray treatment of the osteonecrotic lesion. The patient is always sent home with a jar of ozonated olive oil as a postoperative dressing for the wound.

The influence of ozonized water on the epithelial wound healing process in the oral cavity was observed by Filippi. It was observed that ozonized water applied on the daily basis can accelerate the healing rate in oral mucosa. This effect can be seen in the first two postoperative days. Patient treated with ozone got healed more quickly without the need for systemic medication when compared to the control group. This finding suggested ozonated oil might be effective in the treatment of alveolitis.¹² Application of ozone therapy after tooth extraction and in case of post extraction complications, was found quite useful.¹³

Ozonated water is suitable for prophylactic applications against infections after osteotomies, after surgical interventions like tooth extractions or implant dentistry. After the removal of bone sequestra, Ozone can be used as an alternative to hyperbaric oxygen therapy. Its action is based on the enormous oxidation strength and on the fact that bacteria can be more easily recognized and destroyed by granulocytes and the complement system after contact with ozone. There is an increase in the phagocytosis performance of polymorphonuclear cells in the presence of ozone.^14,15

Endodontics

Ozone in Caries Management:

HealOzone® is a CE-labelled apparatus for clinical ozone therapy of caries. HealOzone, which has been developed by Curozone Inc, Canada and is distributed by KaVo Dental Ltd., converts oxygen to ozone. The ozone is thereafter led to a hand piece fitted with a silicone cup. Differently shaped silicone cups are available that correspond to the form of various teeth and their surfaces. This ensures close contact between the silicone cup and the carious area of the tooth so that the ozone does not escape. The ozone is led through the silicone cup over the tooth for a minimum of 10 seconds. The ozone in the silicone cup is collected again and reconverted to oxygen by the apparatus. Ozone treatment of the caries lesion is completed after 2-3 minutes. Thereafter a solution containing 2% sodium fluoride and 5% xylitol is applied to promote healing (remineralisation) of the caries lesion.

Schematic Representation of the Heal Ozone Device

Ozone has a severely disruptive effect on cariogenic bacteria, resulting in elimination of acidogenic bacteria. The strongest naturally occurring acid, produced by acidogenic bacteria

during cariogenesis is pyruvic acid. Ozone can decarboxylate this acid to acetic acid. It has been shown that remineralization of carious lesions can be encouraged when the production of acetic acid, or other high pKa acids found in resting plaque, buffers plaque fluid. Treatment with ozone gas significantly reduced caries progression, remineralized and arrested carious lesions in patients at high caries risk. It was also observed that ozone treatment being non-invasive provoked least state of anxiety compared to traditional dentistry.^16,17

Ozone in Bleaching

In root canal treated teeth, crown discolouration is a major aesthetic problem, especially in anterior teeth. Conventional walking bleaching requires much more time and results are not oftenly satisfactory. Also, capping the tooth with ceramic crown is not always a good idea. But, now ozone can be successfully used for lightening the yellowish tinge of tetracycline-stained rat incisors.¹⁸ After the application of the bleaching agent, the crown is irradiated with ozone for minimum of 3-4 minutes. This ozone treatment bleaches the tooth within minutes and gives the patient a happy and healthier looking smile.

Ozone in Restorative Dentistry

Ozone gas can be applied prior to etching and the placement of sealant with no negative impact on sound enamel physical properties, including knoop surface microhardness or contact angle.¹⁹ The longer exposure to ozone gas has a strong bactericidal effect on microorganisms within the dentinal tubules of deep cavities, which could result in increasing the clinical success of restorations, with no negative impact on dentin and enamel shear bond strength of adhesive restoration.^20,21

Role in Root Canal

The anaerobic bacteria a positive charge and acidic nature in the infected environment. Ozone is a gas that carries a negative charge and is attracted to the infected environment resulting in disinfection of the area. Standard of care endodontic procedures are employed during diagnostics and treatment. Then Ozone is used for disinfection of the root canals and dentinal tubules. The following steps should be added before the fill of the canal(s).

The flies are coated with ozonized olive oil for lubrication and disinfection.

The canals are prepared and then irrigated with ozonated water and dried.

Before filling a slow insufflations (45-60 seconds) into each canal(s) with a moderate/high concentration of ozone gas using about 30 ml.

The insufflation process allows the ozone mixture to travel electrochemically into the lateral canals and tubules killing the positively charged microbes by oxidizing their cell membranes.

Ozonated Water in Decontamination of Avulsed Teeth Before Replantation:

A high level of biocompatibility of aqueous ozone on human oral epithelial cells, gingival fibroblast cells, and periodontal cells has been found. (Huth KC et al., 2006, Ebensberger U et al.,2002). Two-minute irrigation of the avulsed teeth with nonisotonic

ozonated water not only provides mechanical cleansing, but also decontaminate the root surface, with no negative effect on periodontal cells remaining on the tooth surface before replantation.(Ebensberger U et al.,2002).

Periodontics

Role of Ozone in Dental Plaque 

Ozonated water (4mg/l) was found effective for killing gram-positive and gram-negative oral microorganisms and oral Candida albicans in pure culture as well as bacteria in plaque biofilm and therefore might be useful to control oral infectious microorganisms in dental plaque.²²  ozone gas was found to be toxic  to the human oral epithelial and gingival fibroblast cells and aqueous zone was more biocompatible than gaseous zone.

Role in Root Planning and Scaling

In cases where treatment is by root planing and scaling, the sulci and pockets are initially irrigated with ozonated water by use of a syringe and a canula. This process will reduce the initial pathogenic load on the patient locally and systemically before the root planing and scaling procedure begins. After treatment of a quadrant or half the mouth, each pocket and sulcus is insufflated with ozone gas. The gas goes directly in to the crevicular fluid and the tissues and sterilizes the area, thus eliminating the pathogenic organisms.

Role of Ozone in Hypersensitivity

Smear layer present over the exposed root surface prevents the penetration of calcium and fluoride ions deep into the dentinal tubules. Ozone removes this smear layer, opens up the dentinal tubules, broadens their diameter and allows the Calcium and Fluoride ions to flow into the tubules easily, deeply and effectively to plug the dentinal tubules, preventing the fluid exchange through these tubules. Thus, ozone can effectively reduce the root sensitivity problem immediately and also lasts longer.^23,24

Role of Ozone in Implant Dentistry 

The use of ozone is currently being investigated for the decontamination of the implant surface in peri-implant therapy. Periimplantitis can be prevented with an adequate and steady plaque control regimen. Ozone, a powerful antimicrobial kills the microorganisms causing periimplantitis.²⁵  There is also some evidence on the effectiveness of aqueous ozone application in adjunct to aminoalcohol for decontamination of the implant surfaces.²⁶

Decontamination of Tooth Brush

Ozone application was found to remove the toothbrushes bristles microbiota following conventional brushing.²⁷

Prosthodontics

Microbial plaque accumulating on the dentures is composed of several oral microorganisms, mainly C. albicans. Denture plaque control is essential for the prevention of denture stomatitis. The application of ozonated water may be useful in reducing the number of C. albicans on denture plates.(Arita M et al.,2005) The use of ozone as denture cleaner is effective against methicillin-resistant S. aureus and viruses.(Murakami H et al.,2002) Ozone

can be applied for cleaning the surface of removable partial denture alloys with little impact on the quality of alloy in terms  reflectance, surface roughness, and weight.(Suzuki T et al.,1999) Direct exposure to gaseous ozone was a more effective microbicide compared with ozonated water. Therefore gaseous ozone can be clinically useful for disinfection of removable prosthesis.(Oizumi M et al.,1998) There is also some evidence on the effectiveness of aqueous ozone application in adjunct to aminoalcohol for decontamination of the implant surfaces.(Nagayoshi M, et al.,2004).²⁸

Figure 1   Click here to View figure

Pedodontics

Ozone has been shown to reverse pit and fissures caries in deciduous teeth. Holmes showed that noncavitated occlusal fissure caries in deciduous teeth can be managed successfully using ozone. The conclusion of this study was that ozone is an effective alternative to conventional “drilling and filling” for noncavitated deciduous carious lesions in general dental practice.²⁹ Another study evaluated the anxiety level of children (and their parents)

treated with ozone and found that all children and parents reported significant anxiety prior to ozone treatment.³⁰

Contraindications of Ozone Therapy

Pregnancy, severe anaemia, hyperthyroidism, thrombocytopenia, severe myasthenia, acute alcohol intoxication, recent myocardial infarction, hemorrhage from any organ, Glucose-6-phosphatedehydrogenase deficiency and ozone allergy. Prolonged inhalation of ozone can be deleterious to the lungs and other organs but well calibrated doses can be therapeutically used in various conditions without any toxicity or side effects.³¹ The European Cooperation of Medical Ozone Societies warns that direct intravenous injections of ozone/oxygen gas

should not be practiced due to the possible risk of air embolism.

Ozone Toxicity

Inhalation of ozone can be toxic to the pulmonary system and other organs. Some side effects are epiphora, upper respiratory tract irritation, rhinitis, cough, headache, occasional nausea and vomiting. In the event of an

ozone intoxication, the patient must be placed in the supine position, inhale humid oxygen, and take ascorbic acid, Vitamin E and N acetylcysteine. Further, because of its high oxidative power, all materials that come in contact with the gas must be ozone resistant such as glass, silicon and Teflon.³¹

Conclusion

Ozone is the perfect substance for use in dental procedures. It disinfects the tissues treated and leaves no toxic residues like chlorinated products. It performs this task by oxidizing the cell membranes of pathogenic organisms and killing them. The oxidizing effect of ozone is as follows: one molecule of ozone will kill the same number of bacteria that requires 3,000‐10,000 molecules of chlorine for the same effect and ozone kills them 3500 times faster than chlorine Ozone treatment is excellent as a preventative measure against future decay and dental work needed to correct the damage caused by bacteria. Benefits also include: Eliminates the use of drills and fillings. There is still a need for the highest level of evidence, ie well designed; double-blind randomized clinical trials to justify the routine use of ozone as a treatment modality in dentistry.

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