Objective The existence of keratinized gingival tissue around the mouth of the oral implant is considered as a mucosal barrier around the implant. The existence of keratinized gingival tissue ensures long-term stability of the tissue around the implants. In this study, Meta-analysis was performed to summarize the clinical controlled trials of dental implants in patients with dental implants. Methods An electronic search strategy was performed on EMBASE (Ovid), Cochrane (CENTRAL), Medline, Pubmed, China Biology Medicine disc, China National Knowledge Infrastructure, National Library of Medicine, and Campbell Library. Then, the extraction of the included studies and risk of bias assessment with the recommended tool of Cochrane collaboration was performed until May 2017. Meta-analysis was processed by Rveman 5.3. Three evaluators independently used the Cochrane quality evaluation form to evaluate the methodological quality of the included studies. According to the inclusion and exclusion criteria, we screened related studies, extracted data, and evaluated risk bias. Results At the end of screening, 10 studies with moderate bias risk were included, 8 of which were retrospective studies, and 2 were prospective studies. The main focus of the study was the correlation between the width of the keratinized gingival tissue around the oral implant and the loss of bone around the implant. The outcome indicators included bone loss, height of bone loss, marginal bone loss, and follow-up time are more than 2 months. The Meta-analysis results showed that evident heterogeneity was excluded, the results were stable, and the quality of evidence was high. The results also showed the width of the keratinized gingival tissue around the implant and bone absorption without negative correlation (P<0.01). With the increase in the width of the keratinized gingival tissue and decrease in bone resorption, the keratinized gingival tissue exhibited a protective effect on the peri-implant bone tissue. However, many influencing factors, including bone height around the body and the strength of the immunity, diet, and compliance, need further high-quality control testing to confirm the results. Conclusion No negative correlation was observed between the width of keratinized gingival tissue and the degree of bone loss around the implant. Therefore, in future clinical work, we should preserve the keratinized gingival tissue to increase the bone stability around the implant.
