**4. Antibiotic delivery route with dental implants**

The use of oral antibiotics is one of the most common approaches in treating bacterial infec‐ tions. Antibiotics can be delivered either systemically or by direct placement into the pocket around the dental implant. Each method of delivery has specific advantages and disadvan‐ tages. However, based on clinical and microbiological evidence, the type of microorganisms responsible for the infection is treated on a presumptive basis, founded on probabilistic reasoning [90]. A wide range of antibiotic compounds and dose regiments is presented in the literature. Ideally, antibiotic treatment duration should include the shortest efficient cycle for preventing both clinical and microbiological relapse [91]. However, this short cycle should ideally have certain characteristics such as rapid onset of action; bactericidal activity; lack of propensity to promote resistant mutants; ease of invasion into tissues; activity against nondividing bacteria; unaffected by adverse infection conditions (low pH, presence of pus, etc.); administration at an optimal dose; and an optimal and convenient dosing regimen [92].

#### **4.1. Local use of antibiotics**

Local delivery facilitates the application of antimicrobial agents at levels that cannot be reached by the systemic route. However, these levels need to be maintained at a high local concentration for a long period of time, and the agents should reach the entire affected area, that is, the base of the pocket, in order to be efficient. This type of delivery varies from simple pocket irrigation and specifically placed drug-containing ointments and gels, to sophisticated tools for sustained release of antibacterial agents. However, it is unlikely that mouth rinse or supragingival irrigation could predictably deliver an agent to the deeper parts of the defect because the crevicular fluid rapidly washes out agents from the pockets [93, 94]. Nevertheless, there is a low incidence of side effects with locally applied antibiotics. The use of local antibiotics as an adjunctive in the treatment of peri-implantitis has shown no or limited effect on the reduction of periodontal pocket depth and gain in clinical attachment level [95, 96]. This lack of significant clinical additive effects of local antibiotic supplement is may be due to inadequate exposure of the subgingival bacteria to the compound.

#### **4.2. Systematic use of antibiotics**

Systemic use of antibiotics is commonly recommended when the targeted bacteria are more widely spread, which is beyond the site of initial infection. The periodontal bacteria may be found throughout the whole oral cavity including on non-dental sites such as the dorsum of the tongue or tonsillary crypts [97–103]. However, this colonization of perio-pathogens at various oral ecological niches is not to be regarded as a systemic infection and does not call for systemic antimicrobial treatment. The drawback of systematic administration is the high rate of drug dissemination throughout the body, where only a small portion reaching the subgingival microflora in the periodontal pocket [104]. Moreover, adverse drug reactions are of greater concern. Systemic antibiotics should never be applied as compensation for inade‐ quate oral hygiene.
