**1. Introduction**

Dental implants have become highly predictable routine therapeutic strategy in daily practice for a missing teeth replacement in the partial or total edentulous patients' treatment.

Osseointegration presents close bone-to-implant contact (BIC) and depends on several factors such as implant micro- and macro-design which play crucial roles in long-term implant survival success rate. Implant macro-construction (implant shape, number and shape of implant threads) is designed to improve osseointegration mechanism and obtain implant primary stability resisting detrimental forces occurring during physiological functions [1–4]. Various implant surfaces were developed to enhance osseointegration mechanism accelerating and strengthening bone formation providing better stability [5]. Additional modification of implant

surfaces increases surface roughness with aim to improve bone healing especially in the region with poor bone quantity or quality stimulating bone growth, and enabling immediate or early loading protocols [6]. This modification increases surface roughness as well, making it another

important parameter for effective osseointegration.

The mechanism of osseointegration could invert unpredictably into a pathological process leading to inflammatory reactions in soft tissue (peri-mucositis) or a subsequent bone loss around an osseointegrated implant. This process could cause peri-implantitis onset, and as consequence implant failure [7–9]. As a disease of the modern era, peri-implantitis is defined as a plaque-associated pathological condition characterized by clinical signs of inflammation such as bleeding on probing (BOP) with or without suppuration, peri-implant probing depths increase (PPD), and clinical attachment loss (CAL) along with radiographic bone loss [10].

Major aetiological factors in the peri-implantitis development are virulent pathogenetic anaerobic bacteria (*Porphyromonas gingivalis, Prevotella intermedia, A. actinomycetemcomitans, Tannerella forsythia, Treponema denticola)* isolated from dental biofilm around the implant triggering the deleterious immunological reaction of the host tissue, and causing progressive surrounding bone loss [11]. Furthermore, some facultative isolated a gram-positive pathogen (*Staphylococcus aureus*) and fungi (*C. albicans*) are considered to contribute to peri-implantitis onset [12, 13].

In addition, a myriad of patient-related factors (genetic, diabetes mellitus, cardiovascular diseases, genetics, smoking), local factors (periodontitis, residual cement, poor oral hygiene, etc.), and implant-based factors are introduced as risks that could induce onset and severity of peri-implantitis [8, 14–18].
