## 1 Introduction  
Temporomandibularbular disorders (TMDs) are a group of neuromuscular and musculoskeletal functional disorders of the masticatory system which include the masticatory musculature, the temporomandibular joints (TMJs) and the associated structures [1]. TMDs are highly prevalent, and they represent the second most common cause of orofacial pain [2], although surveys assessed a lack of knowledge among dentits on their symptoms and treatments [3, 4]. One of the most common TMDs' clinical manifestations is temporomandibular myofascal pain (TMP) [5], which causes pain in orofacial region, and consequently disability and deterioration of quality of life. This is a highly significant health problem and about 85% of the general population experience at least one episode during their lifetime, while the estimated overall prevalence is \(\sim\)46% [6]. Myofascal pain is a collection of sensory, motor, and autonomic symptoms that include local and referred pain, decreased range of motion, and weakness; and its main cause is believed to be attributable to myofascal trigger points (MTrPs) [7, 8]. Indeed, for many clinicians and researchers, one or more MTrPs is necessary to ensure the diagnosis of myofascal pain. MTrPs are hypersensitive, palpable areas, made of several contracted motor unities, located in a taut skeletal muscle band [9]. Regarding the orofacial region, MTrPs could be frequently observed in masticatory muscles (i.e., temporal, masseter, lateral pterygoid, medial pterygoid) and neck muscle (i.e., sternocleidomastoid muscle). Investigations about myogenous and internal disorders of TMJ could be developed using the Research Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) to allow standardization and replication of the research on TMDs [10].  
Several therapeutic approaches have been proposed to treat temporomandibular MP. Pharmacological treatment, psychological support, physiotherapy, and occlusal therapy are commonly used alone or in association to treat temporomandibular MP [11; 12; 13]. Noninvasive approaches such as occlusal splints are the most commonly used because of their safety and convenience [14]. Splints are removable appliances, usually made of acrylic polymer with steel claps or linkages that fit over the teeth of either the mandible or the maxilla. Several designs and treatment protocols using occlusal splints have been described in the literature [15]; nevertheless, a low number of randomized controlled trials is available [16] and a valid evidence-based treatment strategy is still debated [16]. The aim of the occlusal splint therapy is to obtain a repositioning of the jaw able to improve muscular comfort and an enhancement in the articular disk relationship with the mandibular condyle [17]. Some studies suggest an occlusal therapy where the jaw is pushed into a more forward position [18], but it should be ideally reoriented in the position which ensures the best comfort for the masticatory muscles and TMJs, as well as the best postural assessment of the whole body. The hypothesis is that an occlusal splint should be personalized on the body postural balance and at the same time able to guide the mandible in a spatial position ensuring both orofacial muscle pain reduction and overall body postural comfort. The relation between body posture and dental occlusion is still debated in the literature [19]. Nevertheless, postural differences between subjects with TMDs and healthy subjects have been observed [20].  
The effectiveness of these personalized splint therapy can be assessed by observing changes in self-reported chronic pain intensity [17] through a pain intensity numeric rating scale (PI-NRS) [21].  
The aim of this study was to evaluate the effectiveness of two complementary mandibular repositioning splints designed after a posture-stabilometric evaluation, thus obtaining a personalized jaw-repositioning splint that could promote temporomandibular myofasical pain reduction in head and neck districts according to PI-NRS during an 8-month follow-up.