# An Orthodontic Treatment Case of a TMD Patient with Maximly Posterior Intrusion Using TsADs
## 3 Discussion  
### Importance of Condylar Position  
Although there are controversies about occlusion as an etiology of TMDs, providing the patient with a stable and well-functioning masticatory system is as important as the establishment of dental and facial esthetics and intercuspal stability in orthodontic treatment [11]. In support of this, [PERSON] has claimed that it is important to achieve orthopedically stable joint positions that contribute to a stable occlusal position [12]. The definition of the proper condylar position has been discussed among researchers for decades, and most recently, this position is being called centric relation (CR). CR refers to \"a maxillomandibular relationship, independent of tooth contact, in which the condyles articulate in an anterosuperior position against the posterior slopes of the articular eminences\". The mandible is restricted to a pure rotation movement in CR, and the patient can make vertical, lateral, or protrusive movements that take a clinically beneficial and repeatable reference position [13]. The occlusion of opposing teeth is defined as centric relation occlusion (CRO) when the mandible is in CR. Maximum intercuspal position (MIP) is defined as \"the most closed position that the mandible can assume, determined by full intercuspation of the opposing teeth, regardless of condylar position\". If occlusal interference occurs during the closing movement of the jaw, opening muscles such as inferior lateral pterygoids contract to protect the interfering teeth, which is called \"protective co-contraction\" [6]. The consistent repetition of the proprioceptive stimulation to the masticatory muscles can promote a deviated closure pattern of the mandible, and the displacement of the condyle position in the MIP can be derived from these patterns of muscle activity. This positional difference of the condyle is known as the MIP-CRO discrepancy [14; 15; 16; 17]. Numerous electromyographic studies have shown that the occlusal interference disrupts the coordination of the function in the masticatory muscle [18; 19; 20; 21; 22; 23]. TMDs can be aroused when a hyperactivation of the muscles produced by protective co-contraction exceeds the patient's musculoskeletal adaptability. [PERSON]'s study reported that almost all symptomatic subjects of TMD (96.9%) exhibited significant condylar displacement in at least one plane [4]. [PERSON] also revealed an 84% reduction in TMD signs and symptoms after full mouth restoration treatment, resulting in almost no MIP-CRO discrepancy compared to a non-treatment control group. Furthermore, he concluded that \"since the condylar position is dictated upon closure of dentition into maximum intercuspation and since the condylar position was shown to be strongly correlated with TMD symptomatology, a statistically significant relationship existed between occlusion-dictated condylar position and symptoms of TMD\" [15]. Clinicians have often measured the amount and direction of MIP-CRO discrepancy chairside by making purely intraoral observations. However, these chairside observations  
Figure 5: Posttreatment records: (**a**) facial and intraoral photographs, (**b**) lateral cephalogram and panoramic radiograph, and (**c**) cephalometric superimposition. Black, pretreatment; blue, post-stabilization; red, posttreatment. lack analytical precision as the patient's mandible is not being guided correctly due to protective neuromuscular reflexes [15; 16; 17; 24]. Another common method to measure MIP-CRO discrepancies is to verify the amount and direction of hit-and-slides at the occlusal level, but some researchers have found that the amount of slides at the occlusal level did not coincide with the 3-dimensional change at the condylar axis level [15; 16; 24]. Comparing the position of the condyle in radiographic images as panoramic and TMJ views is also inadequate due to the distortion of the 2-dimensional images [24].