This article is about the study of antimicrobial potency of guava extract to treat tooth decay due to Streptococcus Mutans.

The guava, psidium guajava, is called the apple of the tropics. The guava tree produces large quantities of fruit. The fruit is round, with a white or yellow skin and a pulp of the same color, although the pulp is sometimes crimson. It ranges from the size of a large cherry to that of a pear or apple. It has high vitamin C content, and also contains potassium, phosphorus, sulfur, and chlorine. It is good for the skeletal and lymphatic systems. The chemical components of guava are eugenol, tannin, amylandin, phenolic aceds, malic acid and flavonoids. Guava is commonly used in treating diarrhea, epidermal lesions, though not proven, in treating hypertension and diabetes.

Streptococcus Mutans is a Gram-positive, facultatively anaerobic bacterium commonly found in the human oral cavity and is a significant contributor to tooth decay. Streptococcus Mutans plays a major role in tooth decay, metabolizing sucrose to lactic acid using the enyzme Glucansucrase. The acidic environment created in the mouth by this process is what causes the highly mineralized tooth enamel to be vulnerable to decay. Streptococcus Mutans is one of a few specialized organisms equipped with receptors that improve adhesion to the surface of teeth. Sucrose is used by Streptococcus Mutans to produce a sticky, extracellular, dextran-based polysaccharide that allows them to cohere to each other, forming plaque. Streptococcus Mutans produces dextran via the enzyme dextransucrase (a hexosyltransferase) using sucrose as a substrate. Conversely, many other sugars such as glucose, fructose, lactose , which can be digested by Streptococcus Mutans, but they produce lactic acid as an end product. It is the combination of plaque and acid that leads to dental decay. Due to the role the Streptococcus Mutans plays in tooth decay, there have been many attempts to make a vaccine for the organism. So far, such vaccines have not been successful in humans. Recently, proteins involved in the colonization of teeth by Streptococcus Mutans have been shown to produce antibodies that inhibit the cariogenic process.

A study was done by a group of graduating medical student in, Cebu, Philippines to know whether guava extract has an antimicrobial effect against Streptococcus Mutans. The study involved the collection of extracted decayed teeth and getting samples and inoculating the samples to culture media, making a guava fruit and leaf extract and doing sensitivity test wherein Bacitracin disc was used as the control. The objective of the study was to determine the antimicrobial ability of guava extract to Streptococcus Mutans and use it to treat tooth decay which is very common in all parts of the world.

The research started by collected of decaying teeth. The decaying portion of each tooth was swabbed and inoculated to a culture medium and was incubated. The extract was made by smashing or juicing a combination of guava fruit and leaves. A Bacitracin disc was prepared. Another sterile disc was dipped to the guava extract and was kept in a cool temperature. After twenty-four hours of incubation, growths of colonies were visible in the culture media. These colonies were then confirmed to be Streptococcus Mutans colonies. Two cultures having abundant and the same growth were then chosen for the sensitivity test. One culture was implanted with the disc dipped in the guava extract, the other implanted with the Bacitracin disc. The two were then incubation. Zones of inhibition or clear zones in the culture media were then measured on the twenty-fourth hour, after forty-eight hours and after seventy-two hours. The zones of inhibition signify the killing power of the content of the discs implanted in the culture. In this case, these are the Bacitracin and guava extract.

After seventy-two hours, a conclusion was made. This state: "Guava extract has some antibiotic effect to Streptococcus Mutans but has a lower potency compared to Bacitracin." The result of this study tells us that guava extract can be utilized for treating tooth decay in areas of the world were availability and affordability of commercialized medicines is a problem and medical practitioners are given no choice but to use the cheapest and the natural ways to do their duties and to treat the sick. The study was not publish nor ignored but it led to other students doing studies similar to it and some doing new studies to support it.

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