Oralhealth is an inextricable component in the well-being of mankind as it affectsthe quality of one’s life by causing substantial pain and discomfort byhindering an individual’s ability to talk, chew, smile, and speak (WHO, 2012). Humanoral cavity is heavily occupied by various microorganisms, most of which arecommensals such as bacteria, fungi, archaea, viruses and protozoa (Wade, 2013). However, oraldiseases are caused by alterations in the equilibrium of the complex ecosystemin the oral cavity (Metwalli etal.
, 2013). Poor oral hygiene, high intake offermented carbohydrate particularly sucrose, use of tobacco, stress and occurrence of diseases are some of the factors that contributeto the alteration of the oral flora which leads to development of oraldiseases. Being the most common diseasethat affects mankind, oral disease is reported to be the fourth most expensivedisease to be treated in most low income or developing countries (Sheihamand Yee, 2002). In addition, according to the U.SDepartment of Health, 1998, about 4 to 8% of the global expenses are to treatoral diseases (Werner etal., 2016).
“The lactic acid bacterium Streptococcus mutans and the yeast Candida albicans belong to the mostcommonly found microorganisms in the oral cavity” (Krumina etal., 2015).Streptococcus mutansare the causative agent of dental caries that occurs from the localiseddissolution of the tooth structure by a demineralization process that takesplace progressively through bacterial fermentation of dietary carbohydratesthat yields acidic by-products. The World Health Organization (WHO) has reportedthat about 60-90% of school children and nearly 100% of adults are affected bydental caries (WHO, 2012). In Malaysia alone, about 90% of the adults,regardless of race are affected by dental caries, with ten tooth damaged by thedisease on average (NOHSA, 2010; Esa et al.
,2014).Streptococcus mutans are both acidogenic (acid-producing) andaciduric (acid-tolerating). They are capable of fermenting sucrose and othersugars to acid, leading to formation of carious lesions as a result from thedissolution of tooth’s crystalline structure (Kabra et al., 2012) and produce acid constantly within the acidicenvironment (Lee, 2014). In addition, Streptococcusmutans produce extracellular polysaccharides (EPS) that facilitatesadherence and accretion of cariogenic bacteria, enhancing plaque formation ontooth surfaces (Lee, 2014). Dental plaque is a complex biofilm consisting of acommunity of microorganisms that develops naturally on tooth surfaces. Themicroorganisms constituting the dental plaque plays a part in the defencesystem of the host by protecting the oral cavity through colonizationresistance by hindering exogenous microorganisms which are often morepathogenic (Babpour et al.
,2009).However, plaque build-up needs to be controlled by practicing good oral hygieneas biofilm in the form of plaque is the causative perpetrator in dental caries(Costerton et al., 1999; Gurenlian,2007) because “microorganismsgrowing in a biofilm are highly resistant to antimicrobial agents” (Donlan and Costerton, 2002). Although Streptococcus mutans are proven to bethe causative agent of dental caries (Loesche, 1986), recent findingshave reported the presence of Candidaalbicans in carious lesions (Barbieri et al., 2007;Metwalli et al., 2013), suggesting a synergistic activity between boththe microorganisms in the progression of dental caries.
Evidently, in a studydone by Beighton et al., 1995, about 58.5% of Candida albicans were isolatedin carious lesions (Nikawa et al., 2003). Apartfrom implicated in dental caries, Candidaalbicans also causes the most common fungal infection of the oral cavity,known as oral candidiasis(Burket et al., 2008). Candidaalbicans are part of the normal human microbiota.
However, similar to Streptococcus mutans, overgrowth of theCandida species results in disease (Akpan and Morgan, 2002). The presence of the microorganism in the oralcavity is estimated to range from 15% to 75% without any symptoms, in otherwords, it remains benign (Ghannoum and Abu-Elteen, 1991; Akpan and Morgan,2002). The fungi shifts from a harmless commensal to a disease causing pathogendue to factors such as poor oral hygiene, compromised immune system, heavysmoking, dental prosthetics and prolonged therapy with antibiotics (Akpan andMorgan, 2002). Overgrowth of Candida albicans must be controlled bymaintaining optimal oral hygiene as otherwise, the condition may lead todiscomfort and pain (Akpan and Morgan, 2002). The infection is more severe inimmunocompromised patients as the infection can be systemic, affecting theentire body by spreading through the bloodstream or upper gastrointestinaltract (Akpan and Morgan, 2002).
The mortality rate for such condition rangesfrom 71 to 79% (Fraser et al., 1992; Akpanand Morgan, 2002)
