Dental implant survival rate in irradiated and non-radiated patients: a systematic review and meta-analysis

Radiotherapy to head and neck has always been considered as a risk factor for rehabilitation with dental implants. Nevertheless, recent data suggest that overall, 5-year implant survival in irradiated patients can be greater than 90%. The purpose of this review was to compare the implant survival rates of irradiated and non-radiated head and neck cancer sites, and discuss the outcomes, through a systematic review approach of prospective and retrospective studies. Electronic searches were performed in the EMBASE, Cochrane, and PubMed/Medline databases up to 2019 Dec, to identify retrospective and prospective clinical studies addressing the subject. This systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The primary variables collected from the studies were the site of tumor, age and sex of the patient, site of implant placement, radiation dosage, frequency and duration of radiotherapy, follow-up duration, implant survival and stability, hard and soft tissue changes after implant placement, any type of biological and mechanical complication, and oral health quality of life (QOL). Fifteen studies including 1097 patients and a total of 4637 implants placed in irradiated and non-irradiated sites, with a follow up duration varying from 6 to 120 months, were selected for the systematic review. The results of the quantitative synthesis suggested statistically significantly better survival rate of implants placed in nonradiated sites, as compared to irradiated sites (p<0.00001). However, the cumulative survival rates over a period of 7-10 years were reported to be comparable. Quality of life (QOL) after implant rehabilitation was not found to be significantly different between the compared groups. Due to the limited number of information, insufficient data was available to draw conclusion on peri-implant complication rate. No relationship was found between age, gender, and implant survival rates. Implant placement in irradiated sites is challenging and often warrants protocol modifications. Although statistically the survival rates at irradiated sites were lower in comparison to non-radiated sites, a strict inclusion criterion in patient selection, timing of implant placement after radiotherapy, radiation dosage and regular oral hygiene maintenance could minimize the chances of implant failure in irradiated patients.