Many oral pathologies, such as dental caries, periodontal disease and peri-implantitis are plaque-related. Dental plaque is a microbial biofilm formed by organisms tightly bound to a solid substrate and each other by means of an exopolymer matrix. Bacteria exhibit different properties when contained within a biofilm. Knowing the mechanisms controlling the formation and development of biofilms can help to understand the emergence and progression of such pathologies and to plan effective treatment. Most periodontal pathogens are common saprophytes of the oral cavity, expressing their virulence only in a susceptible host or when some changes come about in the oral environment. Physical, metabolic and physiological interactions may cause positive or negative effects among the various microbiota present. Such mechanisms of antagonism/synergy select the bacterial population and alterations of its composition affect the balance with the host and may lead to pathology. The effectiveness of antimicrobial agents, as measured through in vitro tests, is dramatically reduced in vivo due to the properties of the microbial community: mature, intact biofilms are less sensitive to such agents, as the exopolymer matrix, bacterial enzymes and slow growth rate hinder the action of chemotherapeutic agents. The present literature review aims to examine the most representative studies, focusing on the characteristics of bacterial communities and the crucial shift from oral health to plaque-related diseases.

This study suggests that circumferential defects could heal clinically without any guided bone regeneration (GBR) in both experimental groups, and that the procedure was virtually free from complications in the postoperative period, probably because of the absence of barrier membranes and/or grafting materials. Histologically, peri-implant defects of over 1.5 mm heal by connective tissue apposition, rather than by direct bone-to-implant contact, but clinically this healing may be very successful. No histological analysis was carried out in the present study, but even the largest residual gaps were filled with hard tissue that could not be probed. Thus, such outcomes can be considered clinically successful. The different rate of bone remodeling around immediate or delayed implants could have implications for the preferred timing of implant placement in sites of high esthetic concern.

Fracture of the implant is one of the possible complications affecting dental implants; it is a rare event but of great clinical relevance. The aim of the present study was to perform a scanning electron microscopy (SEM) fractography evaluation of 7 International Team for oral Implantology (ITI) hollow implants removed because of fracture. The most common clinical risk factors, such as malocclusion, bruxism, and cantilevers on the prosthesis, were absent. Seven fractured ITI hollow implants were retrieved from 5 patients and were analyzed with the use of SEM. SEM analysis showed typical signs of a cleavage-type fracture. Fractures could be due to an association of multiple factors such as fatigue, inner defects, material electrochemical problems, and tensocorrosion.

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