**2. Biofilm formation, a pioneer step of dental caries**

Dental plaque has been discussed as a biofilm (figure 1). Donlan and Costerton (2002) presented the most relevant description of a biofilm.

Fig. 1. Colored scanning electron micrograph of dental plaque (*Streptococcus mutans* bacteria are pink).

They declared that a biofilm is "a microbially derived sessile community characterized by cells that are attached to a substrate or to each other, are embedded in a matrix of extracellular polymeric substances that they have produced, and exhibit an altered phenotype with respect to growth rate and gene transcription."

A biofilm is structured to maximize energy. Degree of organization and multispecies organization characterize the four stages of biofilm growth (Figure 2). There are four stages in the lifecycle whether the organism is planktonic or as member of a biofilm. Stage I is the inactive or least metabolically active state. Transformation from Stage I to Stage II needs significant genetic up-regulation. Stage III involves maturity of the biomass, and total organism concentration can come near 1011 or 1012 colony-forming units per milliliter. At this phase, new antigens may be expressed, genetic exchange enhanced and membrane transport

populations. In order to make continued progress in eliminating this, new strategies will be required (Natcher, 2001).The broad management of dental caries should involve the management of disease as well as the lesion. There is now an intense focus on preventive strategies. Essentially, all preventive treatment strategies either alter or modify the causative

Numerous anti-plaque agents available in the market have been tested for their ability to interfere dental biofilm formation or metabolism. However, due to several undesirable side effects associated with these agents, going along with the increasing global problem with antimicrobial drug resistance, the search for alternate agents is necessary (Tahmourespour, 2011). Targeted agents are so expected to be highly specific, to pose an insignificant resistance development problem, and to have minimal effects on vital human cell functions. A suggested approach to overcome the limitations of the traditional disease management strategies is using inexpensive, effective, stable, novel and natural products as anti biofouling agent. Whole bacteria replacement therapy or using natural products of some bacteria such as the secondary metabolites of them for decreasing of oral cavity pathogens

Dental plaque has been discussed as a biofilm (figure 1). Donlan and Costerton (2002)

Fig. 1. Colored scanning electron micrograph of dental plaque (*Streptococcus mutans* bacteria

They declared that a biofilm is "a microbially derived sessile community characterized by cells that are attached to a substrate or to each other, are embedded in a matrix of extracellular polymeric substances that they have produced, and exhibit an altered

A biofilm is structured to maximize energy. Degree of organization and multispecies organization characterize the four stages of biofilm growth (Figure 2). There are four stages in the lifecycle whether the organism is planktonic or as member of a biofilm. Stage I is the inactive or least metabolically active state. Transformation from Stage I to Stage II needs significant genetic up-regulation. Stage III involves maturity of the biomass, and total organism concentration can come near 1011 or 1012 colony-forming units per milliliter. At this phase, new antigens may be expressed, genetic exchange enhanced and membrane transport

factors in dental caries etiology, such as diet, host, salivary, and microbial factors.

**2. Biofilm formation, a pioneer step of dental caries**

phenotype with respect to growth rate and gene transcription."

presented the most relevant description of a biofilm.

must be investigate.

are pink).

maximized. Stage IV (apoptosis or death) signals detachment or sloughing from the biofilm (Donlan & Costerton, 2002; Thomas et al., 2006).

Fig. 2. Four stages of dental plaque biofilm growth: Stage I attachment (lag [not inert, but metabolically reduced]), Stage II growth (log [exponential growth]), Stage III maturity (stationary) and Stage IV dispersal (death) ( Thomas et al 2006).
