Objective To evaluate the effectiveness of four-handed dentistry versus two-handed dentistry in root canal therapy. Methods The CBM, VIP, CNKI, Wanfang, PubMed, EMbase, and CENTRAL were searched for collecting relevant randomized controlled trails (RCTs) in English or Chinese from establishment dates to August 31, 2011. After quality evaluation and data extraction independently conducted by two authors, the meta-analyses were performed using the RevMan 5.1, and the evidences were graded using the GRADEprofile 3.6. Results Fourteen studies involving 2 906 patients were included. The results of qualitative analysis and meta-analyses showed that compared with two-handed dentistry, four-handed dentistry could obviously shorten operating time, improve satisfaction of patients and doctors, lower the risk of hole pollution, and improve treatment quality, all the differences were significant; but there was no significant difference in postoperative pain during the first week. Based on the GRADE system, the importance of outcomes was “important” or “critical”, while the level of evidences was from “extremely low” to “high”. Conclusion Current evidence shows that four-handed dentistry is superior to two-handed dentistry, but it suggests a weak recommendation to dental workers. Due to the limitations of included studies, more large-sample and high-quality RCTs, and especially performing “cost-effectiveness analysis” as the key outcome are required.