**1. Introduction**

Oral cancer remains as a significant cause of mortality worldwide as most of these the tumors are detected and treated in late stages. The etiology of oral cancer is multifactorial. Tobacco and alcohol are still considered the main risk factors as about 80% of the patients who develop oral tumors are tobacco and/or alcohol users [1].

Additional etiologic factors have also been suggested such as infection by human papillomavirus (HPV) and other oncogenic viruses, immunosuppression states, genetic alterations, and deficient nutrition.

Dental implants are one of the top choices for the oral rehabilitation of partially or totally edentulous patients. The stability and comfort provided by the implantsanchored crowns are among their clinical advantages. Moreover, the success rate of dental implants surpasses 94.6% [2]. However, the soft tissue and supporting structures around the dental implants remain exposed to the oral cavity and may undergo pathological changes. The most frequent lesions are those of inflammatory nature triggered by the accumulation of bacterial biofilm. When the inflammatory lesion is confined to the soft tissue, it is named as peri-implant mucositis. On the other hand, when there is loss of supporting bone, the lesion is known as peri-implantitis. Due to the high incidence of peri-implant inflammatory diseases, some dental professionals treat the lesion but do not send the specimens to the microscopical analysis. About 3.6% of the lesions are malignant tumors (mainly squamous cell carcinomas, the most common malignancy of the oral cavity) [3]. In 2001, the first cases of malignant lesions developing around dental implants were published [4–22]. Since then, the potential relationship of titanium implants with malignant tumor development has been discussed [1, 5, 13].

The aim of this chapter was to offer the readership the most recent information regarding the clinical features of oral cancer around dental implants, its differential diagnosis, and potential oncogenic mechanisms.
