“…In four papers, the patients received implants in areas with sinus lifting procedures (Brizuela et al, 2014;Franceschetti et al, 2014;Kan et al, 1999;Testori et al, 2012); three studies reported the results of immediate implant loading (Agliardi et al, 2010;Cercadillo-Ibarguren et al, 2017;Hinze et al, 2009), one study recruited patients with history of periodontal disease (Correia et al, 2017), and one paper studied implant placement in the HIV-positive patients (Gherlone et al, 2015). Depending on definition of patient smoking status, the included studies were classified into four categories according to the number of cigarettes smoked per day; studies categorizing patients into three subgroups: non-smokers, <10 or >10 cigarettes per day (Agliardi et al, 2010;Balderas Tamez et al, 2017;Bornstein et al, 2008;Brizuela et al, 2014;Correia et al, 2017;Gherlone et al, 2015;Hinze et al, 2009;Peñarrocha et al, 2002;van Steenberghe et al, 2002), and none, <15 or >15 cigarettes per day (Franceschetti et al, 2014;Guido Mangano & Ghertasi Oskouei, 2018;Habsha, 2000;Kan et al, 1999;Testori et al, 2012), and none, <20 or >20 cigarettes per day (Agliardi et al, 2010;Arora et al, 2017) and studies categorizing patients in four subgroups (none, 1-10, 10-20 or >20 cigarettes per day) (Alsaadi et al, 2007(Alsaadi et al, , 2008Cercadillo-Ibarguren et al, 2017;Nitzan et al, 2005;Noguerol et al, 2006;Sanchez-Perez et al, 2007;Twito & Sade, 2014). The NOS score of the one relevant article was less than six poin...…”