Functional analysis refers to various clinical and instrumental diagnostic procedures that provide information about the functional state of the craniomandibular system (masticatory system). With their help, disorders in the interaction of teeth, temporomandibular joints and masticatory muscles, the so-called craniomandibular dysfunctions (CMD), are detected. The dysfunctions recorded by examination can be divided into:
- Arthropathies – disorders within the temporomandibular joint.
- Myopathies – disorders of the muscles of mastication and auxiliary muscles.
- Occlusopathies – disorders of static and/or dynamic occlusion (tooth contacts during jaw closure and during mastication).
Such dysfunctions can manifest themselves, for example, in the form of the following symptoms:
- Cracking, rubbing or pain in the temporomandibular joint.
- Myalgia (muscle pain)
- Chronic tension
- Cephalgia (headache)
Here, the clinical functional analysis (manual functional analysis) is considered the basic examination, which may be supplemented by instrumental functional analysis, imaging techniques and consultative medical examinations.
Indications (areas of application)
I. Clinical (manual) functional analysis detects pathologic (pathological) changes:
- Of the teeth,
- Of occlusion (interaction of tooth surfaces during jaw closure and chewing movements),
- Of the periodontium (the retaining apparatus of each tooth),
- Of the masticatory muscles,
- Of the auxiliary muscles supporting the chewing process and
- Of the temporomandibular joints.
The indication for clinical functional analysis may be:
- If a functional disorder in the craniomandibular system is suspected.
- Before an instrumental functional analysis
- Before initiating further leading measures such as imaging, psychosomatic, orthopedic and/or rheumatological examinations.
- Before an orthodontic treatment
- For follow-up of a craniomandibular dysfunction undergoing treatment.
- As a complementary diagnostic for tinnitus (ringing in the ears).
- As a complementary diagnostics for orthopedic issues.
II. instrumental functional analysis (F.) results in the following indications:
- Following the clinical F. when occlusion disorders are suspected.
- Following clinical F. in the presence of myoarthropathy with severe deviations of joint movements.
- Following the clinical F. in dysgnathia (maldevelopment of the jaws or masticatory system).
- In extensive treatment measures of restorative or prosthetic nature (inlays, crowns, bridges, dentures) both to prevent and treat a craniomandibular dysfunction (CMD), as the newly incorporated restorations are individually adapted in their occlusion.
- If a functional pre-treatment is required for orthodontic or oral surgery.
- In periodontal disease (diseases of the periodontium) and simultaneous suspicion of malocclusion of the teeth.
The procedures
I. Clinical (manual) functional analysis.
Clinical analysis of dysfunction of the craniomandibular system includes:
- Inspection (detection of tooth abrasion (loss of tooth hard substances, i.e., enamel, later also dentin (tooth bone), on occlusal surfaces and incisal edges), occlusal mismatch, exposed tooth necks, damage to the periodontium, hypertrophic musculature).
- Palpation (palpation of the musculature and temporomandibular joints, detection of pain points).
- Auscultation (listening to the temporomandibular joints for sounds such as cracking or rubbing at different stages of the opening and closing movement of the lower jaw).
The findings are usefully documented on a survey form, the so-called Clinical Functional Status of the DGZMK (German Society for Dental, Oral and Maxillofacial Medicine). The clinical examination is supplemented by certain reaction tests such as.
- The provocation test according to Krogh-Poulsen
- The resilience test according to Gerber
- Isometric stress tests
In addition, there are systematically performed joint play techniques, in which the lower jaw is manually guided by the practitioner to infer the cause of the dysfunction based on the reaction of the temporomandibular joints, for example:
- Passive compression: application of pressure by the practitioner on the temporomandibular joint head in different directions to detect irregularities and pain in the joint surfaces and trajectories
- (Dis-)traction and translation: traction on the joint capsule and ligaments to assess inflammation, overstretching, or else hardening due to constant compression
- Dynamic compression: by applying pressure to the joint space during mandibular movements, the range of motion for the discus (cartilaginous disc between the temporomandibular joint surfaces) is narrowed, which has a meaningful effect on the clicking and rubbing sounds depending on the displacement state of the discus.
II. Instrumental functional analysis.
With its help, the static and dynamic occlusion (tooth contacts during jaw closure and during masticatory movements) can be individually recorded. This requires an individual, fully adjustable articulator, to which the following settings recorded on the patient can be transferred:
- Facebow transfer: allows skull-related mounting of the maxillary model; it captures the hinge axis passing through both temporomandibular joints as well as individual reference planes on the facial skull: depending on the articulator system, the Frankfurt horizontal or Camper’s plane is transferred
- Jaw relation determination and arrow angle registration: the positional relation of the upper jaw to the lower jaw is recorded within the framework of intraoral support pin registration. In this procedure, the mandibular movements are recorded on a registration aid inserted in the mouth. The recording results in an “arrow angle” or “gothic arch” and allows conclusions to be drawn about centric occlusion and special features of the temporomandibular joint movement
- Impression taking and making plaster models of both jaws.
- Mounting the models in the individual articulator
- Individual extraoral articular registration: the movements of the condyle (temporomandibular joint head) during occlusal movements are recorded in three dimensions. This not only performs a pure rotational movement, but it is superimposed by a sagittal movement (forward) along an oblique downward condylar path, as well as lateral movements running at an individual angle (Bennett angle and Bennett movement; Fischer angle), which additionally differ depending on the side of the jaw on which chewing is currently taking place (working side and balance side).
- Articulator programming: this is designed, due to the complex individual specifications, correspondingly complex.
Based on the models mounted in this way patient-analog in the individual articulator, the temporomandibular joint movements can be analyzed and conclusions drawn about the functional state of the craniomandibular system. In this way, the results of the clinical functional analysis are verified and appropriate therapy can be initiated. If the functional analysis follows therapy, it serves to monitor progress and success.
