Art Meyer1

BASICS OF FUNCTIONAL CLINICAL AND INSTRUMENTAL DIAGNOSTICS AND PRETREATMENT BEFORE FINAL ORAL REHABILITATION

 

Georg B. Meyer^1a*, Theresia Asselmeyer^2b, Olaf Bernhardt^3c

¹Zentrum für Zahn-, Mund-, und Kieferheilkunde, Universitätsmedizin Greifswald, Greifswald, Germany*
²Klinik für Kieferorthopädie Medizinische Hochschule Hannover, Hannover, Germany
³Poliklinik für Zahnerhaltung, Parodontologie und Endodontologie Universitätsmedizin Greifswald, Greifswald, Germany

^aDMD, PhD, Dr hc, Professor and Chairman*
^bDMD, MA
^cDMD, PhD, Professor

Address for correspondence:

Prof. Dr. Dr. h.c. Georg B. Meyer Director School of Dentistry Ernst Moritz Arndt University Rotgerberstr. 8, 17475 Greifswald, Germany

Abstract

Aim: In the following, the case of a recent patient will be used to exemplify the fundamental clinical course of the dental diagnostics and splint therapy of patients with craniofacial pain.

Summary: The splint therapy presented in the article is the most common and recommendable standard therapy by far, which can primarily effect muscle relaxation and improvement of neuromuscular coordination. Successful implementation requires that, in centric relation and therefore in the splint position, the condyle-disc unit is still largely intact and the interarticular space is not constricted. The therapeutic approach consists in eliminating centric and eccentric occlusal disturbances, rebuilding lost support zones, and changing the mandibular motion pattern in order to improve muscle tone and neuromuscular coordination. If TMJ pain persists nonetheless, targeted, geometric decompression of the very probably compressed articular structures should be performed. To this end, the splint described here can be modified into a decompression splint by inserting an approximately 0.8 mm space holder craniodorsally into the condylar box of the articulator on the side of the joint requiring decompression (also possible bilaterally). This yields a corresponding vertical increase of the splint, which in the patient can produce a ventrocaudal decompression of the compressed articular structures.

Key learning points:

It is strongly suggested that this special, often helpful type of splint therapy be conducted in association with muscle massages and physiotherapy exercises, because the jaw relations must adapt to the premature contacts which arise on the splint at first.

Key words: oral rehabilitation, instrumental diagnostic, craniofacial pain, splint therapy, centric relation

 

Introduction

In the healthy masticatory system, the interplay of cusps and fissures of antagonistic teeth is characterized by the fact that all movements, starting from an obvious habitual occlusion, can be performed without disturbances. The temporomandibular joint also follows these growth-related, geometric patterns (Fig 1).

Corresponding sensory and motor functions of the neuromuscular system are adapted to these patterns, so that no interference occurs during the execution of any activities, e.g., chewing, swallowing, and speech (Fig 2).^4,23,27,28

The causes of functional disturbances, so called craniomandibular disorders (CMD), can vary greatly and extend considerably into other medical disciplines. From the perspective of dentistry, masticatory functional disturbances are primarily caused by occlusal discrepancies if the latter are markedly outside the range of desmodontal tactility of 10 to 30 µm.^16,30 A crucial and often decisive exacerbating factor is psycho-emotional stress (“grinding one’s teeth”),^13,17 but orthopedic problems also influence the masticatory system.^19,28 Neuromuscular functional processes can then no longer be coordinated by the central nervous system, and typically result in often asymmetrical hyperactivity in the musculature. The effects are many and varied (Fig. 3).^6,7,9,21,25

For instance, an epidemiological study on ca. 4000 subjects showed clear relationships between frequent headaches and tension in the masticatory muscles.⁷ Hence, in diagnosing frequent headaches taking an interdisciplinary approach, it is also necessary to look for dental causes and consider dental therapy with, for instance, individual occlusal splints.1,4,11,15

Possible failures should not be attributed to the method, but rather to the differential diagnostic exclusion of dental causes for a given disease/dysfunction. Current controlled studies conclusively show that individually adjusted occlusal splints lead to significantly better muscle relaxation than do only vacuum-

Case report

In the following, the case of a recent patient will be used to exemplify the fundamental clinical course of the dental diagnostics and splint therapy of patients with craniofacial pain. After reaching an initial diagnosis by a short clinical-screening-test,^1,22,23 functional-diagnostic steps in the following order have proven effective:

a) Anamnestic interview

The patient (female, 42 yrs, married, employed) reported to have suffered from massive tension headaches and occasionally tinnitus for the last 20 years, and that the intensity chiefly depended on stress. Neurological, ENT (ear-nose-throat), and orthopedic causes could not be diagnosed by the respective specialists. The patient had heard that dental causes could possibly be the root of the problem.

b) Clinical manual functional diagnostics ^2,3

The palpation of facial and shoulder muscles did not yield any abnormal (asymmetrical) findings (Fig. 4). Examination of mandibular mobility showed opening of circa 40 mm (incisal edge distance) with a slight deviation to the left. No muscle or TMJ pain occurred during this, nor during protrusion and lateral movements of the mandible, which could be performed without restrictions. Clicking or other sounds were also not detectable in the TMJ area, although the patient reported experiencing both TMJ pain and tinnitus during particular stressful situations. The patient also reported having undergone orthodontic treatment between the ages of 11 and 16 years. The headaches began about 5 or 6 years after that, and had occurred regularly since then. She mentioned that she often clenched her teeth, and was surprised to learn that under physiological conditions, about 10 minutes of tooth contact per 24 hours was normal. Before having received this information and instructions in self-observation, she had thought constant contact of the teeth was normal. In general, the patient must learn to recognize and avoid her/his own stress situations, or at least learn not to clench his/her teeth at such times, because this can cause the muscle tension which triggers symptoms. To help patients recognize and avoid clenching their teeth, we give them 3 small, red adhesive dots as “reminders”, for instance, to stick on their computer screen at work.²⁷

For many patients, it has proven helpful to loan them a video on relaxation exercises, muscle massage, and movement training.¹⁴ This is also a means of testing a patient’s willingness to cooperate.

c) Intraoral findings and clinical occlusal diagnostics

Intraorally, this patient exhibited tongue impressions, wear facets/attrition, enamel cracks, and pronounced wedge-shaped defects in the maxilla and mandible.²⁶ On the whole, these are clear clinical signs of stress and/or parafunctions with occlusal causes (Figs. 5 and 6). With the exception of wisdom teeth, dentition was complete, the maxillary and mandibular dental arches were well-developed, and there were no primary positional anomalies. All molars bore partial crowns, one mandibular premolar had a gold inlay, but otherwise there were no restorations (Figs. 7 and 8). Maximal intercuspation was also clinically normal (Fig. 9). But after relaxing her chewing muscles by putting 2 cotton rolls,

in the premolar region for about 2 minutes (Fig. 17) she showed preliminary contacts only in the area of her second molars indicating a discrepancy between centric relation and maximal intercuspation. Severe facets and a cusp fracture could be seen on the second lower molars of both sides (Fig. 8).

2. Instrumental TMJ diagnostics

Because this patient had reported having occasional TMJ problems, axiography was conducted (Fig. 10).²³ For this, we routinely use the Cadiax Compact system by Gamma (Klosterneuburg, Austria) (Fig. 11).²⁸ The device is simple to use and saves time, is very economically priced, and delivers (even without an additional computer) reliable data for both TMJ diagnostics and the adjustment of articulators by many different manufacturers.²³ The electronic registration of the condylar pathways in this patient showed no abnormalities (Fig. 12).

a) Instrumental occlusion diagnostics in an articulator using a centric relation record

This patient exhibited marked clinical signs of occlusal interferences, confirmed by clinical occlusal diagnosis (cotton-roll-) test. After the temporomandibular joints were checked and nothing abnormal was found (see Fig. 12), the mechanical occlusion diagnosis was performed using an articulator and centric relation record.

Impression and Manufacturing casts

Carefully made dental stone casts from maxillary and mandibular impressions are required. Correctly mixed and processed alginate delivers adequate precision, provided that rim-lock trays are used with the correct adhesive (do not use perforated trays!). If the terminal teeth are within the range of the tray, an individual dam with, for instance a silicon material, is sufficient. If a terminal tooth lies outside the tray’s range, an individual extension with a dam, e.g., of thermoplastic material, must be made. An individual palatinal stop must always be constructed for the maxillary tray, trimmed parallel to the dental arch to form an inner tray rim (Fig. 13). Shortly before inserting the impression tray, the occlusal surfaces of the teeth are coated with alginate; meanwhile, the assistant fills the tray. After removing the impression tray, excess alginate is generously trimmed off with a sharp knife in order to avoid unnecessary changes in dimension. Until pouring, the impression is stored in a hygrophore (e.g., air-tight plastic container with a damp sponge); it is never appropriate to wrap the alginate impression in wet paper towels or napkins, even for short-term storage. After pouring the impressions with dental stone, they should be stored in the hygrophore until the stone has hardened (Fig. 14), since this greatly improves the quality of the casts.⁵

In habitual relation, this patient’s finished casts fit tightly with no play, so that occlusal interferences were not discernable in this phase (Fig. 15). The casts are then mounted in the articulator and adjusted to the TMJ, as follows.

Centric relation record

Preparations are made for taking the centric relation record (synonym: bite registration). A mounting plate of tin foil (or “Beauty Pink” wax) is cut to maxillary size, placed between the patient’s teeth, and individually pre-formed through biting down with moderate force, creating a minimal opening of the bite. Next, the top and bottom surfaces of the mounting plate are coated with an adhesive polish. The top surface is then thinly coated with a eugenol liner (Temp Bond). Without using pressure, the plate is adapted to the maxilla, and held by two fingers in the area of the rows of teeth until hardening and removal (Fig. 16).

In preparation for taking the actual registration, the patient should sit upright and relaxed in the chair; the head should never be turned or stretched in any direction.²⁰ To de-couple occlusion and relax the muscles, slightly moistened cotton rolls are placed in the premolar region (Fig. 17).

The bottom surface of the mounting plate is coated with at least 4 aluminium wax drops in the area of cusp impressions. The cotton rolls are removed from the patient’s mouth, and the prepared mounting plate is adapted to the maxilla. Then, with the patient’s muscles as relaxed as possible, the mandible is gently rotated against the plate (Fig. 18). After removing the record, all wax drops must exhibit impressions (Fig. 19). Then, an anatomical transfer bow is put on the patient to register the relation of TMJs and maxilla. On this basis, the maxillary cast is mounted in the articulator (Fig. 20). With the help of the centric record, the mandibular cast is adapted to the already plaster-mounted maxillary cast, and then also mounted in the articulator using plaster (Fig. 21).

In this case, a protrusion record for individually adjusting the horizontal condylar path inclination was not necessary, since the values for these angles (SKN) and the mediotrusion paths (TKN) were already available from the electronic registration (see Fig. 12).

After removing the centric relation record, the casts mounted in the articulator showed a considerable discrepancy between the registered centric relation position (of the condyles) and the maximal intercuspation position of the teeth; premature contacts were visible in the molar area (Fig. 22) corresponding very well to what we had found clinically (cotton-roll-test). In habitual relation, the separated base of the maxillary cast indicates the presence of interference (Fig. 23). As a rule, malocclusions of this nature tend to lead to distraction effects in the TMJs with relatively moderate traumatization of these structures.

b) Confirmation of initial diagnosis: checking the centric relation record with therapeutic biteplates (centric splint)

Although the clinical findings from this patient – including the past orthodontic treatment which, as she said, was conducted without articulators adjusted for maxillomandibular relations – speak for the correctness of the observed occlusal interferences, it was important to confirm the initial diagnosis with an interim splint therapy. The principle

(centric splint) is very simple: The discrepancy found in the articulator is equilibrated through a custom-made bite-guard splint with equal support of all teeth (Fig. 24).

At this point, a warning is necessary: do not insert non-individualized splints, e.g., solely vacuum-drawn heat-treated polyvinyl sheets, because these tend to worsen the symptoms in the intermediate term.⁸ In this particular patient, even more pronounced posterior premature contacts would result.

Asselmeyer has described the manufacture of an appropriate bite-guard splint.⁵ Composite is carefully and precisely added onto an individualized vacuum-drawn heat-treated splint (which was first trimmed in the articulator to leave the smallest occlusal height possible) until equal support of all posterior teeth results.

This occlusion concept corresponds to that of the Michigan splint by Ramfjord and Ash.⁴ In contrast to natural teeth and restorations, the splint allows only the respective load-bearing cusps to contact, which antagonistically occlude with the splint. With a maxillary splint, this would involve just the buccal mandibular cusps, and with a mandibular splint, only the palatinal maxillary cusps would be involved (Figs 25 and 26).

Fundamentally, maxillary and mandibular splints each have specific advantages and disadvantages. This patient was given a maxillary splint, because this is the only one which can reconstruct an individual anterior tooth guidance which has a proven additional muscle-relaxing effect.^12,18 For this we use the Contour Curve Former (CCF), with which characteristics of anterior guidance can be formed to the individual patient (Figs 27 and 28; see also Fig. 4).

Insertion of splint

The splint was inserted into the patient’s mouth (Figs. 29 and 30). Attention must be paid to tension-free seating. Exactly as in obtaining the centric record, the relaxed mandible is guided against the splint. A disclosing paper 10 to 20 µm thick is used to check whether the load-bearing cusps produce even contacts on the splint; if necessary, corrections can be made with a milling cutter. subsequently, excentric movements are checked. In the initial phase, a slight canine guidance should be aimed for; in the present case, the individually formed anterior tooth guidance was checked and corrected. The patient is advised to wear the splint as often as possible, especially at night, but not while eating and not necessarily when speaking at length (lectures, etc.); the splint must be worn during periods of stress.

Re-examination and correction

The first re-examination must be conducted within the first 3 days if possible, or at least a telephone call should be made to the patient within this time. Within the next few weeks, several correction appointments are usually necessary, due to the fact that a change (improvement) of the mandibular position can be associated with increasing muscle relaxation, and the splint must be adjusted accordingly. In the present case, the patient was completely complaint-free within 3 months. She reported not being willing or able to do without the splint – at least when under stress.

After about 6 complaint-free months, a new centric relation record was taken, which was then used to mount the casts in the articulator with the goal of a final occlusion analysis and further treatment planning. For instance, this could consist of orthodontic measures which can be simulated with a diagnostic set-up in the articulator. Plans for restorations can also be made in the articulator by diagnostic trimming and/or diagnostic waxing-up.

Glasses for the Dentition

In the end, the patient described here did not choose any of the options mentioned above. When needed (primarily at night and under stress), she simply inserts the splint. As of the present day, she is free of headaches, TMJ problems, and tinnitus, despite continuing to work in a very intensive and responsible occupation. Recently, the patient reported not needing the splint at all during a sailing holiday in the Mediterranean. Stachniss therefore very appropriately termed the bite-guard splint “glasses for the dentition”.²⁹

Sumary

The splint therapy presented here is the most common and recommendable standard therapy by far, which can primarily effect muscle relaxation and improvement of neuromuscular coordination.²⁴ However, successful implementation requires that, in centric relation and therefore in the splint position, the condyle-disc unit is still largely intact and the interarticular space is not constricted. The therapeutic approach consists in eliminating centric and eccentric occlusal disturbances, rebuilding lost support zones, and changing the mandibular motion pattern in order to improve muscle tone and neuromuscular coordination.²² As a rule, this also leads to a more physiological positioning of TMJ structures with a positive, therapeutic effect.

If TMJ pain persists nonetheless, targeted, geometric decompression of the very probably compressed articular structures should be performed. To this end, the splint described here can be modified into a decompression splint by inserting an approximately 0.8 mm space holder craniodorsally into the condylar box of the articulator on the side of the joint requiring decompression (also possible bilaterally).²⁴ (Fig 31,32) This yields a corresponding vertical increase of the splint, which in the patient can produce a ventrocaudal decompression of the compressed articular structures. It is strongly suggested that this special, often helpful type of splint therapy be conducted in association with muscle massages and physiotherapy exercises,^14,27 because the jaw relations must adapt to the premature contacts which arise on the splint at first.

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