Occlusal bite force changes during fixed orthodontic treatment in patients with different vertical facial morphology

Abstract

In orthodontics, treatment planning and treatment progress requires in depth knowledge and understanding of the masticatory muscles and their relationship to different facial morphology. Occlusal Bite Force (OBF) is used to assess the functional status of the masticatory mechanism (Bakke, 2006). There are several factors influencing the occlusal bite force. They include age, gender, cranio-facial morphology, periodontium, temporomandibular joint disorders and dental status (Koc et al., 2010). Long-faced individuals exhibits smaller values of bite force and short-faced type of craniofacial morphology has been associated with stronger bite force (Abu Alhaija et al., 2010). Bite force reduces significantly through age, particularly in women (Shinogaya et al., 2001). Weak periodontium may reduce the threshold value of the mechanoreceptors causing changes in biting force (Morita et al., 2003). The greater bite force in the posterior dental arch depends on the larger occlusal table, contact area and the number of teeth loaded during the biting action (Babic et al., 2002). \n \nMaximum Voluntary Bite Force (MVBF) and malocclusion has a strong relationship. In earlier reports the decrease in MVBF due to malocclusion was well documented (English et al., 2002). Greater bite force found in individuals with normal occlusion, followed by Classes I, II and III malocclusion respectively (Araujo et al., 2014). Reduction in maximum bite force and number of occlusal contacts was reported in children having unilateral posterior cross bite in comparison with those possessing ideal occlusion (Sonnesen and Bakke, 2007). It is reported that bite force values decreased during the initial period of active orthodontic treatment but, with time, recovered to pretreatment levels (Sawsan et al., 2012). It was also noted that occlusal bite force increased after orthodontic treatment (Winocur et al., 2007). Pain and discomfort due to orthodontic appliances and changing occlusal relationships during orthodontic treatment produces reduction in occlusal bite force (Yawaka et al., 2003). Assessment of bite force during orthodontic treatment gives a clue to the orthodontist regarding the type of mechanics to be used. It is also helpful in diagnosing any interferences in the stomatognathic system during orthodontic treatment (Sathyanarayana et al., 2012). Only few studies have addressed the issues of occlusal bite force change during fixed appliance orthodontic treatment (Sawsan et al., 2012, Yawaka et al., 2003). While changes in bite forces have been shown to occur during routine orthodontic treatment, and that bite forces vary with varying facial patterns, there is no clarity whether the change in bite force during orthodontic treatment is same for all patients or if it differs with different types of facial patterns. Hence this study assess the changes in occlusal bite force during the first 6\u202fmonths of fixed appliance orthodontic treatment and the time taken to reach ideal bite force in patients with different vertical facial morphology.