The DIR® concept is based on a multi-stage treatment plan that begins with a functional dental history and a brief dental report.
This is followed by a special functional analysis, the so-called axis 2 diagnostics, as well as a comprehensive dental function check with manual-clinical diagnostics and further instrumental diagnostics.
The final therapeutic measures are divided into a temporary DIR® splint therapy and the implementation of the “new bite” in a definitive prosthetic restoration.
The range of indications for the DIR® concept includes both the prosthetic restoration of patients with CMD syndrome and the fabrication of new dentures for functionally healthy patients.
Diagnostics
As part of the DIR® concept, the FunktioCheck Pro® software documents the preliminary dental findings.
The type of complaints and previous visits to the dentist from other specialist disciplines are recorded as part of the functional dental history. In the brief dental findings, missing canine guidance, non-age-appropriate abrasion of the teeth in the sense of grinding facets and abrasions or The brief dental findings record missing canine guidance in the sense of grinding facets and abrasions or wedge-shaped incisions, tooth loosening, tilting and migration, gingival recessions with Still-man clefts and McCall’s garlands, pain during muscle palpation, temporomandibular joint noises as well as restrictions and asymmetrical mouth opening movements, resulting in a three-grade probability statement for the presence of a functional disorder and a recommendation for further findings.
Axis 2 diagnostics
The special functional analysis carried out when there is a high probability of CMD, known as axis 2 diagnostics, is highly relevant for the success of subsequent treatment, as if there are causal psychosocial disruptive factors, a supplementary or even complete assumption of treatment by the psychologist or psychiatrist is indicated. The various forms of anxiety disorders are often associated with an altered perception of pain and are objectively assessed using a Graded Chronic Pain Scale and a pain perception scale, whereby an evaluation sheet can be used to assess the patient’s level of psychological stress.
Manual-clinical diagnostics
The subsequent manual-clinical diagnostics allow an assessment of a manifest arthropathy with examination of the temporomandibular joint function to exclude or confirm the presence of a disc perforation or a disc displacement, condylar osteoarthrosis, hypermobility, capsulitis or inflammation of the bilaminar zone. The morphological or structural remodeling processes in the hard tissues should of course be confirmed radiologically (MRI). Manifest myopathy is assessed by performing standardized masticatory muscle examinations using the isometric tension test and muscle palpation.
Instrumental functional analysis
The manual functional analysis is followed by the instrumental functional analysis with the DIR® system, which is also carried out on functionally healthy patients as part of prosthetic planning. The electronic measuring method is based on the arrow angle or support pin registration according to Gerber with recording of the marginal movements of the mandible under physiological masticatory pressure and without reference to occlusion.
Centric position as target bite
Once the DIR® measurement has been completed, the centric position determined is encoded in the patient’s mouth as a so-called target bite by inserting the support pin into a fixation plate under defined chewing pressure and injecting silicone between the rows of teeth. This is followed by transfer to the articulator. In the subsequent model analysis, an occlusion analysis is performed, whereby the deviation of the habitual occlusion or the current actual state from the centric occlusion or the target bite is documented.
DIR® splint therapy
The corresponding DIR® splint therapy is planned on the basis of this result. There are three different types of biomechanical DIR® splints. The adjusted splint according to DIR® takes both condyles out of compression. With the relief or relaxation splint according to DIR®, the two condyles are moved anteriorly or retrally by a small amount (1 to 2 mm). With the DIR® reprogramming splint, the right or left condyle is rotated slightly and the contralateral condyle is rotated back. A recent MRI study provided evidence of a centric position of the temporomandibular joint during DIR® splint therapy.
Centric condyle position
The centric condylar position corresponds to the ideal, physiological condylar position. It is the occlusion-independent, not laterally displaced, individual three-dimensional position of the condyle-discus complex in the mandibular fossa with maximum muscle relaxation (resting tone with resting length of the muscle fibers) and normal width of the bilaminar zone in the habitual resting (floating) position of the mandible with a lowering of the mandible (SKD) of about 3 mm in the anatomical neutral zero position. The apex of the condyle lies in a vertical line below the apex of the mandibular fossa and the turning point between the mandibular fossa and the articular tubercle lies in a horizontal line in front of the apex of the condyle. The centric condylar position is therefore muscle-controlled and can be described as myocentric. It should not be defined as an exact mathematical position in the sense of a point centric, but as a biological comfort position in the sense of a freedom in centric with an intra- and inter-individual range of variation.
Wearing time of the DIR® splint
The respective DIR® splint is worn for at least six months with a follow-up measurement after three months. The prerequisite for the implementation of the final prosthetic restoration with continuous monitoring by the treating dentist is that the patient is completely free of symptoms and that the lower jaw position has been successfully reprogrammed in the patient’s occlusal memory.