Comprehensive dental diagnosis and treatment planning for occlusal rehabilitation: a perspective

The indications for administering invasive dental treatments to patients with temporomandibular disorders have been controversial since the second half of the last century.^1,2 The need to implement reproducible dynamic measurement devices and clinical and instrumental functional analysis throughout dental diagnosis and treatment is equally mandatory.³ Patients are increasingly aware of high-quality dentistry and demand better longevity from their dental therapies. Due to the increase in functional occlusion-related diseases in the last few decades⁴ and rapid improvements in dental materials and technology that have created new options, the dental community needs to take a fresh look at the appropriate diagnostic and planning techniques that should be used prior to administering invasive dental treatment. This will ensure the delivery of the optimal therapeutic benefits to patients.

The temporomandibular joints (TMJs) and their spatial position within the glenoid fossae are the key parameters for undisturbed function, not only of the masticatory system but also as a receptor and mediator of body posture.^5–10

Craniomandibular system, neuromuscular system, and occlusal guidance system

The functional joint space of the TMJ is relatively narrow. Any deviation and/or deflection of 0.6–0.8 mm in any direction (cranially, dorsally, or transversally) produces a loading situation for the components of the joints (bilaminar zone, articular disc, ligaments, and bony structures).^11–15 This leads to a neuromuscular avoidance reaction, i.e. compensation within the masticatory system¹⁶ and the buffer regions of the neighboring organ systems (head position, shoulder girdle, vertebral spine, etc.).^17,18

The physiological position of the TMJs is secured and dominated by static and dynamic occlusion. This prevents muscle hyperactivity by evenly distributing the forces of the masticatory and associated muscles.^19–21 The occlusal scheme, which includes the spatial position of the occlusal plane, plays a very important role in these tasks.²² It is evident that a sequentially guided occlusion with canine dominance leads to posterior dis-occlusion, the avoidance of protrusive, laterotrusive, and mediotrusive posterior dental interferences and seems to be best suited for providing undisturbed function of the neuro-muscular system.^23–26 Deviations from this occlusal scheme, in terms of the so-called malocclusions or occlusally dominated malfunctions, can easily lead to the development of painful symptoms in the form of a temporomandibular disorder.^27,28

Furthermore, it has been definitively proven that occlusal malfunction causes deflective TMJ positioning,^29–32 which can lead to the development of tissue damage, such as the loosening of the ligamentous apparatus,³³ inflammation of the capsular components, displacement of the condyle and articular cartilage,³⁴ or, in the worst case, resorption of the bony structures of the TMJs.³⁵ These kinds of tissue injuries can lead to symptoms such as muscle hyperactivity, neck pain, headaches, and other neurological symptoms such as muscle or joint pain and/or decreased range of motion of the mandibular movements in a very high percentage of cases.^36–45

Occlusion seems to be a ‘fine-tuning’ neurologic feedback system that guides mandibular movements against maxillary dentition.^46–49 At the same time, occlusal contacts seem to be responsible for maintaining the condylar position within a physiological range.^12–16

Knowing that occlusal sensitivity is within the range of 0.02–0.03 mm,^48,50–55 that TMJ has a ‘deflection’ tolerance of only 0.6–0.8 mm,^12–15,49 and that the angular difference between the steepness of the articular eminence and the contra-lateral canine guidance of any skeletal class is ≤10°,^53–55 it becomes clear that dentistry is dealing with a highly individual and highly complex organ system.^3,56–58

Diagnostic approach

In order to obtain an optimal diagnosis and treatment plan, as well as devise a custom-tailored treatment approach for any individual patient, as much information as possible must be collected about each individual using a maximum standardized approach.^3,49,59,60 These records should not only include thorough anamnesis and a clinical functional analysis that includes accurately mounted casts and articulator occlusal analysis, but also precise and reproducible kinematic measurements/tracings of the 3-dimensional condylar paths.^3,49,61 This allows the clinician to determine the real-time motions of the mandible and synchronize these records with the static and dynamic occlusion on the articulator, which then becomes a simulator of the patient’s mandibular motion.⁶⁰

If necessary, additional analyses, including imaging techniques and additional medical consultations, are needed to confirm the differential diagnosis. In this way, the differential diagnosis can prove occlusion as a causative etiological factor for the development of the signs and symptoms of temporomandibular disorders.^62,63

Therapeutic approach

Administering a reversible initial therapy to an occlusion is a must when pretreating patients with a potentially occlusion-dictated temporomandibular disorder.^{45, 64–68} The symptoms should positively and significantly decrease before considering invasive treatments (e.g. selective functional equilibration, orthodontic treatment, rehabilitation of occlusal surfaces (onlays, inlays, partial crowns), and/or prosthodontic reconstruction) .

In the case of a positive outcome following reversible pretreatment, i.e. after objectively (by a decrease of the clinical signs) and subjectively (by the patient) reevaluating the patient’s condition in a standardized way, definitive occlusal treatment is the next logical step following the initial therapy.^{45,46,59,65,66} After confirming the diagnosis, occlusal rehabilitation must be executed after strictly considering the physiological condylar position and the exact application of occlusal sequential guidance with canine dominance.^{3,4,49,53–55}

Using precise, objective, and reproducible diagnostic and measurement techniques, and applying a standardized treatment protocol for occlusal rehabilitation, it is possible to obtain highly predictable therapeutic results.^44,59,61 In addition, it is also feasible to monitor the progress of the reconstructive and orthodontic dental treatment, as well as to adapt ongoing treatments at any time if changes that occur require further diagnosis and correction.^67,68