Lack of association between dental implants and oral squamous cell carcinoma.

Design A systematic review of the literature to identify and evaluate the epidemiologic profile, and screen for possible risk factors and spectrum of clinical characteristics of oral squamous cell carcinoma (OSCC) surrounding dental implants, was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines.Data sources A search of two databases, Medline and CENTRAL, was undertaken, limited to articles published in English from the oldest records until 10 July 2018. Google Scholar was the grey literature searched. The references list in the included articles was assessed for further inclusion suitability.Study selection Participants included patients diagnosed with OSCC surrounding dental implants. The comparator or control was patients diagnosed with OSCC without dental implants. The outcome was epidemiology and carcinogenesis. The considered study designs were case reports, case series and retrospective studies. Article selection was performed by screening titles and abstracts individually by two blind review authors using the Rayyan platform based on the inclusion criteria. Then, the full text of the selected articles was assessed to identify the eligible articles, and the reasons for exclusion were reported. When a consensus was not achieved between the review authors, a third review author, who acted as a tiebreaker, was consulted.Data extraction Two independent review authors extracted the data using a specific extraction form in Microsoft Office Excel (Microsoft Corporation, Redmond, WA, USA). The extraction form consisted of authors, publication year, country, study design, number of cases, age, sex, risk factors, region of interest, the clinical aspect of the lesion, radiographic findings, the period between implant placement and tumour diagnosis, treatment, and follow-up. The time reported in the studies was converted to months for comparison. A third review author validated the accuracy of the information collected.Synthesis Two independent review authors assessed the risk of bias by applying the Joanna Briggs Institute (JBI) Critical Appraisal Checklist (CAP) for Case Reports and the JBI CAP for Prevalence Studies (for example, retrospective studies). Disagreements were resolved by consulting a third co-author. The Grading of Recommendation, Assessment, Development and Evaluation (GRADE) tool evaluated the certainty of the evidence of the main outcomes. A PRISMA flow diagram was presented, and a table summary of descriptive characteristics of the 33 included studies. Among the figures available, bar graphs represented the 'clinical features' according to the previous history of oral potentially malignant disorders and regarding the malignancy of oral potentially malignant disorders. In addition, a stacked line with markers represented the sex of the number of cases, displaying the time until diagnosis after implant placement and the time to disease progression.Data analysis A qualitative synthesis was provided. No quantitative data synthesis nor inter-rater agreement assessment was conducted.Results Thirty-one case reports and two retrospective studies, published between 1983 and 2020, met the eligibility criteria. The total sample consisted of 63 patients (male = 44.5%) with an average of 66.7 years (range = 42 to 90 years). Oral potentially malignant disorders were found in 29 patients (46%), of which 65.5% were female patients. The most common lesions were oral lichen planus and leukoplakia in female patients (52.6% and 31.5%) and male patients (20% and 60%). In 25 patients (39.6%), there was information missing about the presence of potentially malignant oral disorders, and oral hygiene status was reported in only 17.4% of the cases. Fifty-six patients (88.8%) of OSCC with dental implants were located in the mandible, and the most common clinical presentations of OSCC with implants were exophytic mass (46%) and ulceration (36.5%). Peri-implant bone loss assessment was performed in 51 patients (80.9%), of which 44 (86.2%) had peri-implant bone loss. Thus, most of these lesions were originally treated as peri-implantitis.Conclusions Most patients with OSCC next to their dental implants were female patients lacking known risk factors, and the common location was the mandible with an exophytic mass or ulceration presentation. A major concern is that the clinical and radiographic features of OSCC could be misdiagnosed as peri-implantitis. Thus, OSCC should be considered in persistent lesions surrounding dental implants. Several of the included reports were missing previous medical history and follow-up information. Hence, better case series and studies are required to support or reject the notion of an association between dental implants and OSCC.