Abstract: For proper orthognathic and orthofacial surgery planning, the patient’s head needs to be scanned without deformation of the facial soft tissue mask, with the mandible in “centric relation (CR)” and ideally in its individual “natural head position (NHP)”:

Abstract: Background Numerous condylar repositioning methods have been reported. However, most of them are 2-dimensional or are complex procedures that require a longer operation time and a highly trained surgeon. This study aims to introduce a new technique using a condylar repositioning plate and a centric relation splint to achieve a centric relationship. Methods We evaluated 387 patients who had undergone surgery for skeletal jaw deformities. During the operation, a centric relation splint, intermediate splint, final centric occlusion splint, and condylar repositioning plate along with an L-type mini-plate for LeFort I osteotomy or a bicortical screw for bilateral sagittal split ramus osteotomy were utilized for rigid fixation. The evaluation included: a physical examination to detect preoperative and postoperative temporomandibular joint dysfunction, 3-dimensional computed tomography and oblique transcranial temporomandibular joint radiography to measure 3-dimensional condylar head movement, and posteroanterior and lateral cephalometric radiography to measure the preoperative and postoperative movement of the bony segment and relapse rate. Results A 0.3% relapse rate was observed in the coronal plane, and a 2.8% relapse rate in the sagittal plane, which is indistinguishable from the dental relapse rate in orthodontic treatment. The condylar repositioning plate could not fully prevent movement of the condylar head, but the relapse rate was minimal, implying that the movement of the condylar head was within tolerable limits. Conclusions Our condylar repositioning method using a centric relation splint and mini-plate in orthognathic surgery was found to be simple and effective for patients suffering from skeletal jaw deformities.

Abstract: Centric occlusion (CO) and centric relation (CR) have been controversial topics in dentistry for almost 100 years. The concept of CR emerged due to the search for a reproducible mandibular position that would enable the prosthodontic rehabilitation of patients needing denture treatment. The following case study is unique because of 2 questions. Which mandibular treatment splint position (CR or CO) was appropriate for the initial and eventual final treatment of this patient for her temporomandibular disorder/myofascial pain and dysfunction? Also, how might the mandibular position of CR and CO affect the size and shape of the airway? The airway's size and shape is important as it relates to sleep-disordered breathing and potentially leading to obstructive sleep apnea later in life. The authors believe this is the first case report describing how mandibular position of CR and CO may affect not only TMJ position but also the airway shape and size in three dimensions.

Abstract: Purpose: The aim of this pilot study was to assess temporomandibular joint disc movement relative to the condyle among centric relation (CR), physiologic rest position (PRP), and maximal intercuspation position (MIP) in healthy patients without signs or symptoms of any temporomandibular disorder. The hypothesis was that as the condyle rotated clockwise or translated anteriorly, the disc would also move in an anterior direction. Material and methods: Magnetic resonance images were obtained on 20 volunteers in CR, physiologic rest, and MIP. Three investigators measured the location of the disc among the different mandibular positions. Results: Disc location differences between CR and PRP exhibited the widest range of measurement. The largest amount of disc protrusion relative to the condyle was found between CR and PRP on the right side. The largest amount of disc retrusion relative to the condyle was found between CR and MIP on the right side. The hypothesis was not supported by the results. Conclusions: A...

Abstract: The objective of this study was to verify the influence of the use of Class II intermaxillary elastics on centric relation (CR) to centric occlusion (CO) occlusal discrepancy. A total of 30 patients had been at the contention stage for at least three months were divided in two groups: G1 15 had been submitted to intramaxillary orthodontic mechanics only, and G2 15 had used Class II intermaxillary elastics. Distances of horizontal and vertical overlap and the distance or coincidence of the mandibular dental midline in relation to the maxillary midline were measured in CR and CO positions. Intergroup comparisons were performed using the Mann–Whitney test. No statistically significant differences (P>0.05) were found between G1 and G2. Both in the horizontal and vertical directions, these discrepancies were smaller than or equal to 1mm in 96.66 % of the patients. In the transverse plane, there was no discrepancy in 63.33 % of the patients, and in 33.33 % these discrepancies were equal to 0.5 mm. The use of Class II elastic didn’t be capable of increasing the occlusal discrepancies between CR and CO.

Abstract: Malocclusions with anterior crossbite are a major esthetic and functional concern for patients. This case report presents a 27-year-old Syrian female who was diagnosed with a class 3 malocclusion, combined with anterior crossbite, deep bite, concave profile, and inadequate maxillary incisor exposure. There was a centric occlusion (CO)/centric relation (CR) discrepancy and the mandible could be manipulated to near edge-to-edge incisal relation. Correction was done by class 3 intermaxillary elastics on upper and lower mini-implants for the first 6 months, followed by preadjusted edgewise appliance. The objective of implant-supported elastics was to adapt the patient for the CR condylar position without dental effect. Treatment was completed in 24 months with satisfactory dental and facial relationship.

Abstract: The aim of the study was to improve the efficiency of the final stage of orthodontic treatment. The study included 32 patients divided into two groups of 16. Orthodontic treatment was performed using a bracket system active self-ligation straight arc technique with step adjustment anthropometric quantitative evaluation system (The ABO Model Grading System). Centric occlusion and centric relation were analyzed at baseline and after treatment by mandible position indicator MPI (Mandibular Position Indicator). The first group received treatment according to conventional protocol, in the second group braces were readjusted by indirect bonding after ABO anthropometric measurements. The efficiency of orthodontic treatment using ABO system at the late stages of adjustment in the second group was significantly higher than in the first group (p=0.002248; p=0.023431, respectively). MPI analysis in the first group in 10 (62.5%) patients showed mismatch of centric occlusion and centric relation not seen in the second group. In 3 (18.75%) patients of group 2 the difference did not exceed 0.5 mm which was considered normal. Thus, the application of ABO anthropometric system followed by readjustment of incorrectly positioned brackets by indirect bonding promotes MPI values improvement, which in turn allows getting the most accurate, and stable results of orthodontic treatment.

Abstract: The comprehensive dental rehabilitation of complex prosthetic cases is often associated with increasing occlusal vertical dimension and transferring horizontal mandibular position in centric relation. The newly defined position of the mandibula should be functionally and esthetically evaluated for a longer time period before irreversible measures are performed. This case report discusses in detail a time-saving and economic direct method for increasing occlusal vertical dimension with long-term provisional composite restorations using a simplified injection molding technique and illustrates the complete intraoral and laboratory workflow.