Centric relation—A biological perspective of a technical concept

Abstract

BackgroundFew terms and concepts have been so extensively debated in dentistry as the words ‘centric relation’ (CR). Debates involve its biological, diagnostic and therapeutic usefulness.MethodsA review of the literature on the current concepts on CR as a diagnostic or therapeutic aid in dentistry was provided. Clinical trials assessing the superiority of one CR recording method over the others to identify patients with temporomandibular disorders (diagnostic use) or to manage patients with prosthodontic or orthodontic needs (therapeutic use) were tentatively included.ResultsDue to the absence of literature addressing either of the above targets, a comprehensive overview was provided. The diagnostic use of CR as a reference position to identify the correct position of the temporomandibular joint condyle within the glenoid fossa is not supported and lacks anatomical support. From a therapeutic standpoint, the use of CR can be pragmatically useful in prosthodontics as a maxillo‐mandibular reference position when occlusal re‐organization is warranted and/or when the position of maximum intercuspation is no longer available.ConclusionsThe derived occlusal goals from a diagnostic misuse of CR are generally the result of circular reasoning, that is a technique is based on the recording of a certain condylar position that is believed to be ‘ideal’ and the treatment is considered successful when such position is shown by the specific instrument that was manufactured for that purpose. The term ‘Centric Relation’ might be replaced with the term ‘Maxillo‐Mandibular Utility Position’.

Does increasing vertical dimension of occlusion in centric relation affect muscular activity? An electromyographic study

“…This is probably not due to questions being settled but rather to a general decrease of interest in occlusion in the last years. The recognition of the increasing importance of non‐occlusal factors in TMD as well as weak or absent evidence supporting the use of occlusal therapies in the treatment of TMD, 8–19 are probably important reasons for this decreased interest.…”

“…In the past some authors, albeit without supporting data, have been advocating a supposed biologic advantage given by CR 8 . However, the clinical concepts of considering CR as a preventive measure to protect the temporomandibular joint (TMJ) compared to maximal intercuspal position (MIP) as well as of utilizing a precise maxillo‐mandibular relation to treat dysfunctions have been rejected 8–14 . There is currently a wide consensus to avoid irreversible changes in dental occlusion as the target for temporomandibular disorders (TMD) treatment 12–19 …”

“…Currently, rather than dysfunctional patients, clinicians routinely face conditions requiring important occlusal modifications in otherwise functionally healthy subjects, typically in esthetic restorative cases, where extensive prosthetic reconstructions, orthodontic therapy, and complex surgical‐orthodontic treatments may be necessary to achieve the required esthetic goals (Figure 1). Regardless of the reasons why treatment has been decided (restoring tooth wear, replacing extensive tooth loss, periodontal breakdown, a combination of all the previous conditions or even just an improvement in esthetics required by the patient), there is a general consensus around the advantages to refer to some reference position starting from which the patient's occlusion can be reorganized after the maximal intercuspal position has been modified 1–7,13,14 . Indeed, in spite of decades of philosophical controversies, 3–5 in a clinical perspective the role of a maxillo‐mandibular relation change should be rather a practical than a biological goal 13,14 .…”

“…Regardless of the reasons why treatment has been decided (restoring tooth wear, replacing extensive tooth loss, periodontal breakdown, a combination of all the previous conditions or even just an improvement in esthetics required by the patient), there is a general consensus around the advantages to refer to some reference position starting from which the patient's occlusion can be reorganized after the maximal intercuspal position has been modified 1–7,13,14 . Indeed, in spite of decades of philosophical controversies, 3–5 in a clinical perspective the role of a maxillo‐mandibular relation change should be rather a practical than a biological goal 13,14 . The position should allow for easy reproducibility and be harmless to the patient 13,14 …”

“…Indeed, in spite of decades of philosophical controversies, 3–5 in a clinical perspective the role of a maxillo‐mandibular relation change should be rather a practical than a biological goal 13,14 . The position should allow for easy reproducibility and be harmless to the patient 13,14 …”