Mandibular retrusion deformity correction presents a surgical challenge, even for senior surgeons, in terms of establishing an optimum condyle–glenoid relationship intraoperatively, and keeping this good relationship postoperatively stable via a reliable osteosynthesis method (de et al., 2013; Hernández-Alfaro et al., 2017). According to the literature, it is well known that condylar positional changes after advancement of the retruded mandible through bilateral sagittal split ramus osteotomy (BSSRO) that is fixated with a miniplate may trigger long-term condylar morphological changes due to adaptive remodeling (Watzke et al., 1990; Arnett, 1993; Dolce et al., 2002; Borstlap et al., 2004). These changes have been extensively studied as possible side effects after orthognathic surgery (Kerstens et al., 1990). Therefore, the resulting condylar remodeling process is secondary to an imbalance between mechanical stress applied to the condyle and the host's adaptive capacities that could be a cause of relapse (de Cirugía Ortognática and Sistemática, 2012; Catherine et al., 2016).

This challenge is greater in some class II cases because of a bony gap formed between the proximal and distal segments across the oblique osteotomy line, due to counterclockwise mandibular rotation (de et al., 2013; Hernández-Alfaro et al., 2017). Furthermore, proximal segment flaring, resulting from pressure on the lingual part of the dental segment at the mandibular angles, could enhance this bony gap and create an area of condylar compression, with subsequent resorption and later relapse, as suggested by Arnett et al. (Arnett et al., 1996a, 1996b). Interestingly, this flaring is mainly a temporary effect, since 50% of the original flaring disappears by 1 year postoperatively, as demonstrated by several studies (Arnett et al., 1996b; Becktor et al., 2002, 2008). Therefore, during fixation of the two segments, more surgeons tend to add an adjunctive fixation method, in the form of either a bicortical screw or a two-hole plate, in the retromolar region posterior to the miniplate with monocortical screws (MP), to reduce this bony gap and secure enough condylar flexibility for postoperative passive accommodation at the glenoid fossa (Shetty et al., 1996; Tharanon, 1998; Pereira et al., 2010; Albougha et al., 2015; Hernández-Alfaro et al., 2017).

Although most previous studies have focused on stability after BSSRO fixation with this method, to the best of our knowledge, no previous studies have investigated the effect of this combination on condylar displacement and morphological changes (Shetty et al., 1996; Tharanon, 1998; Joss and Vassalli, 2008; Pereira et al., 2010; Han and Hwang, 2015; Hernández-Alfaro et al., 2017).

Therefore, this retrospective three-dimensional radiological comparative study was conducted as a trial to fill this gap, through evaluation of the effect of adding either a bicortical screw (BS) or a two-hole plate (2HP) to miniplate osteosynthesis on condylar displacement and remodeling after mandibular advancement through BSSRO. Additionally, the correlation between age, amount of advancement, and amount of follow-up on these parameters was studied. Our null hypothesis was that the addition of either AFM to the single miniplate after BSSRO advancement to correct retruded mandible can prevent the lateral displacement of the condyle, thereby reducing the risk of long-term condylar resorption.