“…Systematic reviews (Kern, Kern, Wolfart, & Heussen, 2016; Klemetti, 2008; Roccuzzo et al., 2012) , and the consensus statement (Thomason et al., 2012) cite strong evidence that 2 implants are adequate number to retain IMO, mainly because four implants revealed only slightly reduced implant loss rates (Kern et al., 2016). That said, IMO retention by single implants installed in the mandibular midline is fairly common and reduces cost and treatment time (Carletti, Pinheiro, Meira, Amaral, & Rodrigues Garcia, 2019; Passia et al., 2017); however, MF improvements are not always observed (Amaral, Souza, Pinheiro, Campos, & Garcia, 2019) and a higher frequency of prosthesis maintenance is required (Passia, Wolfart, & Kern, 2019).…”