**1. Introduction**

Periodontal disease is a significant veterinary health problem of companion dogs [1]. Periodontal disease refers to a group of inflammatory diseases. In both humans and dogs the initial stages of periodontal disease are observed clinically as red and inflamed gingivae, defined as gingivitis. Without treatment to remove, and disrupt the dental plaque, gingivitis may progress to periodontitis [2]. Periodontitis, the later, irreversible stage of the disease, is an inflammatory disease of supporting teeth tissues [3]. The primary etiological factor in the initiation and progression of periodontal disease is dental plaque [4]. Dental plaque is the community of microorganisms found on a tooth surface as a biofilm, embedded in a matrix of polymers of host and bacterial origin [5]. It is believed that enzymes secreted by dental biofilm bacteria as well as bacterial antigens activate the host inflammatory response initiating disease [6]. Dental calculus that represents mineralized bacterial dental biofilm is considered as secondary etiological factor in periodontal disease [7]. Dental calculus itself is relatively non-pathogenic and, despite its rough surface, is not the direct cause of inflammatory processes, but mainly has an irritant effect.

In addition, the presence of dental calculus leads to greater biofilm accumulation by creating a rough surface [8]. Dental calculus is always covered with a layer of dental biofilm, so it plays an important role as retention factor in the colonization of microorganisms [9].
