**1. Introduction**

In the light of the latest classification adopted during the World Panel for Periodontal Classification in 2017, periodontitis is a chronic, multifactorial, inflammatory disease associated with dysbiotic biofilm of the plaque, and is characterized by progressive destruction of dental attachment apparatus [1]. The most characteristic features of the disease include clinical attachment loss (CAL), pocket deepening (PD), bleeding on probing, and loss of bone tissue which can be radiologically observed [2].

Periodontitis constitutes a significant social problem due to the incidence of the disease, and the consequences associated with failure to take up treatment. Loss of teeth that takes place over the course of periodontitis results in the loss of prosthetic support areas, and significantly affects the quality of life of patients as well as the way they function in the society.

Epidemiological studies from 2013 show that 26% of Warsaw residents aged 35–44 require specialist periodontal treatment [3]. In the nationwide studies, the ratio was 16% in the same age group [4] and 19.7% in the group of people aged 65–74. In a 2012 study conducted by Konopka et al. [5], according to the definition of Page and Eke, periodontitis was diagnosed in 23.1% of the patients; in 1.6% of them the disease was severe. According to the definition by O ffenbacher et al., 41.2% of the examined patients were diagnosed with periodontitis (0.7% of p1, 22.7% of p2, and 17.8% of p3). In the studies conducted in 2017 [6], the incidence of periodontitis according to DCD/AAP among the residents of Wrocław and Oława aged 65–74 was 30.7% in the cpi4 group, i.e., 47.9, out of which the disease was severe in 21.9 cases [6].

The scaling and root planing procedure (SRP) [7] is considered to be the gold standard in nonsurgical treatment of periodontitis. However, subgingival instrumentation does not eliminate all pathogens from the pocket, therefore reinfections and relapses are very common, especially in the case of deep pockets. One of the promising alternative procedural protocols is a combination of classical subgingival instrumentation (SRP) and intrapocket antibiotic administration in a suitable carrier, which makes it possible to obtain long-term minimum concentration of the drug inhibiting periopathogen development.

Such procedure is known as local drug delivery (LDD). There are many limitations to general antibiotic therapy on periodontal grounds, and it is accompanied by many adverse e ffects. For this reason, in 1979 Goodson postulated local application of tetracycline [8] administrated into the pockets in the form of vinyl acetate copolymer fibers (Actisite). Local application reduces or eliminates some adverse e ffects associated with general antibiotic therapy, especially bacterial resistance and allergic reactions. Moreover, concentrations of the active substance in LDD in the area of administration considerably exceed minimal inhibitory concentration (MIC) and enable administration to the particular area that requires treatment [9]. Since 1979, many preparations that release antibiotic active substances and can be applied into the pockets have been introduced to the market and to clinical use. They di ffer in terms of the carrier, the active substance and the form of administration. Currently, preparations with tetracycline (2 mg), minocycline in 2% concentration and doxycycline in 10% concentration have been in use. These preparations consist of one or two components and can be easily administered to the periodontal pockets.

One of the new forms of LDD for intrapocket application that has been recently introduced is Gelcide. It is a patented mixture that consists of piperacillin and tazobactam combined by a carrier. The preparation is packaged into two vials. After mixing the contents of the vials, the preparation gelifies, and forms a coating that seals the periodontal pocket. Thanks to these properties, the active substances of the product should be retained in the area to which the preparation was administered. The components of Gelcide are slowly released in concentrations exceeding MIC over the period of 8 to 10 days. The coating is permeable, but it is insoluble to fluids—it protects the pocket from exposure to bacteria of the oral cavity and from further irritation and infection.
