Journal of Craniomandibular Function, 03/2021

Aim: The goal of the present study was to determine both distances and spatial relationships between centric relation (CR) and maximal intercuspal position (MIP) in the condylar area, and to demonstrate their implications for dental practice. Materials and methods: Eighty-one subjects were assigned to one of four licensed dentists, who recorded their CR by six different checkbite registration methods. Maxillary casts were mounted after transferring the individual hinge axes to Dentatus articulators by facebow transfer, and mandibular casts were mounted in precise alignment with the apex of a Gothic arch tracing. A fifth colleague took measurements in the condylar area after transferring the casts to a special measuring articulator. Distances and spatial relationships were calculated as the means of triplicate measurements with casts mounted in CR and of duplicate measurements with casts articulated in MIP for each bite registration method. Results: Overall, the spatial mean distance between CR and MIP for all methods combined was 0.86 ± 0.52 mm (min 0.05 mm; max 3.14 mm). The corresponding mean distance was 0.47 mm on the purely sagittal plane. The mean position of the condyles in CR was only slightly dorsal and cranial to that in MIP but with considerable variation in all spatial directions. Conclusions: MIP moves the condyles out of CR to a position that deviates from CR by an average of 0.8 to 0.9 mm spatially and by approximately 0.5 mm on the sagittal plane, with slightly anterior and caudal deviation as well. Hence, the spatial position of the condyles in MIP varies considerably from that in CR. This has substantial implications for dental practice, eg, when performing terminal molar tooth preparation or interpreting condylar position indicator device readings. Keywords: static occlusion, maximal intercuspal position, centric relation, reproducibility, condylar position indicator device, temporomandibular joint compression, temporomandibular joint distraction, freedom in centric relation

Aims: To investigate whether a shortened dental arch (SDA), as identified by reduced posterior occlusal contacts, is a risk factor for the progression of temporomandibular joint (TMJ) intra-articular disorders (ID), as identified using imaging techniques. Methods: This multisite, prospective observational study with a mean follow-up period of 7.9 years had a sample of 345 participants with at least one temporomandibular disorder (TMD) diagnosis at baseline. SDA was defined as reduced occlusal posterior support due to lack of occlusal intercuspal contacts in the molar region on the left and/or right side. SDA was assessed at baseline and at follow-up with metalized Mylar Tape. The presence or absence of a TMJ ID and the specific TMJ ID diagnoses for baseline and follow-up images were established by a calibrated, blinded radiologist at each of three sites by using bilateral magnetic resonance imaging for soft tissue imaging for disc displacement and by bilateral multidetector computed tomography or cone beam computed tomography for hard tissue imaging for degenerative joint diseases. Wilcoxon rank sum test and linear regression analyses were used to test for an impact of SDA on TMJ ID status. Results: At baseline, TMJ ID status of either side was not significantly affected by the presence of SDA on the ipsilateral or contralateral side of the jaw (all P > 0.05). Furthermore, the presence or absence of SDA at baseline was also not a significant predictor for progression of the TMJ ID status between baseline and follow-up (all P > 0.05). Conclusion: The findings of this study suggest that there is no significant effect of SDA on progression of TMJ ID. (Original article published in J Oral Facial Pain Headache 2018;32:329–337. doi: 10.11607/ofph.1910) Keywords: intra-articular disorders, observational study, risk factor, shortened dental arch, temporomandibular joint

Despite a variety of educational activities in the field of temporomandibular disorders and orofacial pain, such as courses, congresses, and publications, detailed knowledge about how respective lecturers and authors proceed in the management of their patients is lacking. To fill part of this knowledge gap to some extent, the spectrum of patients who consulted with the author at the University Center for Dental Medicine Basel in January 2021 is presented in this article. These patients were new referrals, ongoing cases, and recall patients, ranging from simple to complex, textbook-like to exceptional. Summary descriptions and individual case histories are used to explain the author’s evidence-based diagnostic and therapeutic approach, and many tips are given. Monthly statistics and concluding thoughts round off the article. Keywords: mandibular mobility, masticatory muscles, temporomandibular joints, orofacial pain, temporomandibular disorders, occlusal disturbances, history taking, diagnostic imaging, oral splints, evidence-based dentistry