**2. Clinical features of oral cancer around dental implants**

A review of literature available until September 2021 was conducted in the PubMed/Medline database using the term "Oral squamous cell carcinoma around dental implants." Only cases with definitive microscopic diagnosis of OSCC arising in the soft tissue around one or more dental implants were included. The literature review revealed 43 cases of patients with OSCC around dental implants in the 19 published manuscripts [4–22]. All clinical and epidemiological information about the sample is summarized in the **Table 1**.

The age of patients with oral cancer around dental implants ranged from 61 to 75 years old. There was a predominance of females (24 cases - 57.14%) when compared to males (18 cases - 42.86%). The typical clinical appearance of oral cancer around dental implants was an exophytic mass (20 tumors—47.62%) with few cases presenting as ulcer (4 tumors—9.52%). The bone osteolysis was frequently observed in the area of tumor causing the implant loss in some patients. The tumors affected mainly mandible (38 cases—90.47%) of the patients with multiples osseointegrated implants. Of note, oral cancer around dental implants is frequently clinically mistaken as peri-implantitis (**Table 1**).

Although peri-implantitis is the most common local risk factor for dental implant failure, the development of oral cancer involving the soft tissue around the titanium also impact the quality of life of the patient negatively. The oral cancer can manifest as hypertrophy, erythema, and/or ulcerative lesion of the soft tissue, and these features are similar to inflammatory peri-implant diseases such as peri-implantitis and/or peri-implant mucositis, as described by others [7, 10, 11]. Furthermore, these inflammatory peri-implant diseases frequently present the same epidemiological pattern and risk factors for oral cancer, that is, patients older than 60 years old and

*Oral Cancer around Dental Implants: Are the Clinical Manifestations and the Oncogenic… DOI: http://dx.doi.org/10.5772/intechopen.101156*



*M = Male; F = Female; Pre.Rep.CA = Previously reported cancer; PI = Peri-implantitis; OL = Oral lichen planus; NA = Not available. \* Patients who smokers and/or drinkers were considered.*

#### **Table 1.**

*Demographic and clinical features of patients diagnosed with oral squamous cell carcinoma around dental implants.*

chronic tobacco and/or alcohol consumers [1]. Although there are protocols for peri-implantitis treatment, frequently, the peri-implant tissue removed during this surgical treatment is not submitted for histopathological analysis [23, 24]. Then, the number of reported cases of peri-implant malignancy seems to be low in mouth but it may be being underreported by health professionals [24]. Recently, in a study of 111 biopsies of peri-implant lesions, 3.6% of those had histopathological diagnosis of oral squamous cell carcinomas [3]. Another investigation demonstrated that 2.9% of 68 dental implant-related lesions were oral squamous cells carcinomas [25].

**Figure 1** illustrates a case report of an edentulous 64-year-old woman. She had an exophytic mass associated with ulcerated area and covered by a yellowish membrane in the anterior region of the mandible. The lesion was surrounded multiple osseointegrated implants (**Figure 1A**). She did not report adverse habits, for example, tobacco or alcohol consumption. Periapical radiographic exhibited an ill-defined bone destruction underneath the area of the lesion (**Figure 1B**). The histopathological analysis exhibited keratinizing well-differentiated epithelial neoplastic cells, some undergoing atypical mitosis, and invading the subjacent fibrous connective tissue (**Figure 1C**). The diagnosis of oral cancer was confirmed.

The early diagnosis of malignant tumors around dental implants is challenging because incipient lesions may resemble inflammatory peri-implant lesions [1, 2, 4–7, 10, 12, 15–18, 21]. In the **Table 1**, 14 out of 43 cases of oral cancer surrounding dental implants (33.33%) had the primary diagnosis of peri-implant lesions. Therefore, this clinical misinterpretation might delay the diagnosis of oral cancer facilitating its dissemination and resulting in a worst prognosis of the disease. These facts underscore how critical is the histological exam of every lesion around dental implants surgically removed. Furthermore, the peri-implant lesion that does not present the classical features of an inflammatory condition and that does not respond to conventional treatment, particularly if the patient has risk factor for oral cancer, should be submitted to the biopsy and histopathological analysis [23–25].

*Oral Cancer around Dental Implants: Are the Clinical Manifestations and the Oncogenic… DOI: http://dx.doi.org/10.5772/intechopen.101156*

#### **Figure 1.**

*Clinical and microscopic findings of oral squamous cell carcinoma around dental implants. a) Exophytic ulcer covered by necrotic tissue at the anterior-inferior alveolar ridge.b) Periapical radiograph showing an ill-defined bone loss in the peri-implant region. c) Neoplastic squamous epithelium-infiltrating subjacent submucosa with corneal pearls and discrete pleomorphism. d and e) epithelial cells with atypical mitotic figures infiltrating the tissue.*

### **3. Risk factors for oral cancer around dental implants**

The etiology of oral cancer is multifactorial. OSCC is the most prevalent oral malignant tumor and it is associated with lifestyle risk factors such as alcohol consumption and smoking [26]. Curiously, tobacco smoking is also the predictor of dental implants failure and more smokers have post-operative infections and peri-implant crestal bone loss than nonsmokers [27, 28]. Although the information about lifestylerelated factors that predispose to oral cancer was incomplete in most of cases included in the **Table 1**, 34.88% of patients diagnosed with squamous cell carcinoma around dental implants were smokers and/or drinkers. These overlapping risk factors may drive the clinician to attribute the onset of an atypical lesion involving dental implants to a deficient or anomalous immune response of a patient who consumes tobacco and/ or alcohol. However, it is essential that the clinicians are aware that the classic signs of inflammation persist in such patients and that these features are useful to distinguish a benign from a malignant lesion. Additionally, the histopathological analysis remains as the gold standard for the diagnosis of lesions located in the oral cavity [23].

A well-defined concept is that patients with previous history of cancer have higher risk of developing other tumors. Twenty-three (54.76%) of all cases of squamous cell carcinoma around dental implants arose in patients with history of cancer. Interestingly, we observed that 19 (82.60%) patients had OSCC previously. Furthermore, other patients had lung [6, 15], intestine [15], thyroid [17], and

breast [17, 22] cancer previously. As the development of OSCC has been also associated with genomic instability and genetic predisposition [1], one can hypothesize that a patient who had a malignant lesion are more susceptible to local aggressions such as the contact of the soft tissue with dental implant materials.
