Sudden, Severe, Idiopathic Occlusal Relationship Change Coexisting with Pain-Related Temporomandibular Disorders: A Case Report

Abstract

The article presents a case of a young female patient who sought help due to myofascial pain followed by a sudden occlusal change (anterior open bite (AOB)) that occurred shortly after the administration of a soft night guard that had been previously provided by a general dentist. Palpation of the masseter and temporal muscles elicited the presence of familiar pain. After magnetic resonance imaging of temporomandibular joints, which ruled out disc displacement, the final diagnosis was myalgia. Since the patient had myalgia and malocclusion, the therapy included treatment of both conditions. Temporomandibular disorders (TMDs) management included a combination of kinesiotherapy, pharmacotherapy, and a stabilization splint. After TMD symptoms had resolved, the patient underwent an orthodontic evaluation. Cephalometric analysis revealed skeletal class II, retrognathic face, convex profile, and normal vertical growth pattern. Orthodontic treatment included a fixed appliance with vertical intermaxillary elastics. After 19 months of treatment, both sides achieved acceptable occlusion with Class I. Since the patient had myalgia and severe malocclusion, it was important to follow a systematic diagnostic and therapeutic workflow. Although it is impossible to establish a relationship between TMD symptoms and orthodontic therapy, patients who have TMD symptoms should have their pain resolved through a conservative treatment protocol before commencement of orthodontic treatment. The beginning of orthodontic therapy comes into consideration only when the TMD pain resolves.

Introduction

The role of occlusion in temporomandibular disorders (TMD) has been a controversial issue. In the past, occlusion was frequently stated as one of the major etiological factors for TMD. Many theories, based on this presumed connection, have advocated the use of therapeutic approaches such as occlusal splint, anterior repositioning splint, occlusal adjustment, etc. In contrast, various dental interventions, including orthodontic treatment, have been considered possible causes of TMD without real evidence (1). New scientific research suggests that TMD is a multifactorial disorder with complex etiopathophysiology (2). The idea that some orthodontic anomalies are associated with a greater risk for TMD onset (anterior open bite, class II malocclusion, and unilateral posterior crossbite) has been tested previously and to this day this connection has not been confirmed by sufficient evidence. Therefore, it is not believed that TMD results from any particular type of malocclusion (3-5).

The available literature suggests that occlusal changes, especially those occurring abruptly, may be secondary to TMD (5). Such abrupt changes in occlusion are often idiopathic without a clear cause or they may represent a reaction to structural changes in the joints that may appear as a result of joint effusion due to inflammation, condylar degenerative changes, condylar degenerative changes combined with disc displacement, condylar fractures, or changes in muscular contractions and tone (6). One of potential changes which is often observed in combination with TMD, is an open bite. The anterior open bite (AOB) refers to a malocclusion characterized by a lack of teeth contacts in the front teeth area and negative overbite (7). Severe AOB, with just a few contacts in the posterior area, can cause speech and chewing difficulties that may affect a patient's oral health-related quality of life. It may be a consequence of internal derangements of the TMJ associated, or not, with condylar degeneration. Rarely, this malocclusion is also associated with wearing inadequately fabricated or designed occlusal devices. For instance, an occlusal splint that only partially covers the dental arch leads to the supraeruption of uncovered teeth (8). Negative consequences of inadequate occlusal appliances are relatively common in clinical practice, hence it is important that the patient's existing occlusal scheme is always maintained and not violated by the construction of an appliance (8).

In this case report, we described a sudden, severe, and idiopathic AOB that occurred shortly after the administration of a soft night guard that had been provided by a general dentist to manage the TMD symptoms. Our multidisciplinary approach included first TMD pain management (pharmacotherapy, kinesiotherapy, hard acrylic occlusal splint) followed by orthodontic treatment of AOB (fixed orthodontic appliance).

Case report

A young female patient visited the Department of Prosthodontics at the Clinical Hospital Center Zagreb. Her main complaint began at the age of 18, when she noticed significant pain in the masticatory muscle region on both sides of the face, with a score of 7 on the Numerical Pain Rating Scale (NPRS), as well as limitation of mouth opening with accompanying headache in the temporal region and pain in the teeth in the molar region.

Sometime after the appearance of the first symptoms, she started hearing non-specific sounds in both temporomandibular joints (TMJ). When soreness in the region of the masticatory muscles worsened and the opening of the mouth became restricted the patient went to the family general dentist who provided her with a soft night guard. After the administration of the soft night guard, the symptoms did not subside and a new symptom appeared: a sudden change in the occlusal relationship. Based on the patient's medical history, 2 months after wearing the night guard, a noticeably open bite appeared which was not present before. The patient said that she was unable able to meet her anterior teeth. Yet she did not provide any documentation (photos or plaster models), hence there was no evidence of her original occlusion. However, she submitted a photo that she had taken a few months ago, before the appearance of her first symptoms via Snapchat application, possibly distorted by a photo filter, showing her teeth in what appeared to be a correct bite position.

Diagnosis

Clinical examination - diagnosis of temporomandibular disorders

A TMD expert who was trained in TMD diagnosis performed a complete clinical evaluation of the patient. The diagnosis of TMD was made according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) (9).

The clinical examination consisted of palpation of the masticatory muscles, temporomandibular joints, and surrounding structures, measurements of mandibular movements, and assessment of the presence and nature of TMJ sounds. Examination revealed that the pain was largely located in the left and right masseter muscle area, radiating to the temporal areas. The pain-free opening was 20 mm, and the maximum unassisted opening was 27 mm, both measured at an interincisal distance (Figure 1). During the maximal opening, familiar pain was present in both masseter muscles (Figure 1). Familiar pain was also confirmed by palpating masseters bilaterally. Additionally, sounds in the joints were not confirmed. An AOB with no occlusal contacts from the left second molar region to the right second molar region was present. The examination also revealed a visceral swallowing pattern (tongue thrusting). According to the Oral Behavioral Checklist (OBC), which assesses the frequency of oral habits, the patient experienced frequent sleep-related oral behaviors and occasional waking-state oral behaviors, with an overall OBC score of 21 representing a milder risk for TMD.

Figure 1.

The maximum unassisted opening was measured as the distance between the maxillary and mandibular central incisors and defined as the largest amount of opening that a patient can achieve regardless of pain and discomfort (a); the patient is pointing to the area of pain during the evaluation of mouth opening (b); soft night guard provided by a general dentist (c)

After clinical examination, an assessment of a previously utilized soft night guard was conducted. The night guard had uneven occlusal contacts (only on second molars) indicating that either patients' occlusal contacts had changed or the appliance had not been constructed in the proper occlusal position (Figure 1).

Anatomical impressions were taken and stone casts were made and transferred into a semi-adjustable dental articulator ARTEX (Amann Girrbach AG, Koblach, Austria) for additional occlusal analysis and planning of occlusal adjustments.

In order to evaluate muscle function and efficiency by directly and objectively detecting their electrical potentials, surface electromyography (EMG) was performed (Figure 2). EMG recordings were taken bilaterally from the masseter and anterior temporal muscles during maximum clenching in the maximum intercuspal position. The electrodes were applied parallel to the muscle fibers. Muscle activity was analyzed during isometric voluntary contractions, with the patient performing maximum-strength occlusion for approximately 5 seconds.

Figure 2.

Surface electromyography: the electrodes were applied as parallel as possible to the muscle fibers (a); EMG activities of the masticatory muscles during clenching - the strongest activity was recorded for the left temporalis muscle (b)

The patient was referred to Magnetic Resonance Imaging (MRI) for further diagnosis. Two experts in MRI diagnosis concluded that the images of the TMJs showed no evidence of bone discontinuity, ruling out the possibility of abrupt degenerative changes in the joint. Both joints showed hypomobility when the mouth was opened. However, a series of slices showed that the disc was in the proper position when the mouth was opened in this manner. Therefore, it was believed that disc displacement was not the cause of limited opening (Figure 3).

Figure 3.

Sagittal MR image of a temporomandibular joint taken in the intercuspal position showed a slightly anteriorly positioned disc (left); at maximum opening condyle movement is decreased and the disc in the normal position in relation to the condyle and the articular eminence (right)

After careful evaluation of signs and symptoms and MRI findings the final diagnosis, according to DC/TMD, was myalgia.

Orthodontic examination - diagnosis of the open bite

Clinical examination revealed a slightly convex profile and facial symmetry with competent lips (Figure 4). Intraorally, the upper right first molar was in class II while the upper left first molar was in class III. Transversal dental relationships were normal. The only occlusal contacts were at the second molars bilaterally (Figure 4). Overjet was 3 mm, and due to an open bite, the overbite was measured at -2 mm. Tongue thrusting was also present. A plaster model analysis showed no arch length discrepancy. The values for Bolton analysis were 73.8% in the anterior ratio and 89.3% in the overall ratio, hence the discrepancy in the anterior segment was present.

Figure 4.

Pre-orthodontic treatment extraoral (a) and intraoral (b) photographs

Cephalometric analysis Zagreb 82 MOD revealed a skeletal class II (ANB=5.9°) retrognathic face (n-s-ar=132.6°) with a convex profile (10.5°) and normal vertical growth pattern (10). The maxillary base was counterclockwise rotated (5.4°). Lower incisors were labially inclined by 108.9° (Table 1).

Table 1. Cephalometric analysis Zagreb 82 MOD.

Variable/ Varijable		Standard value/ Standardne vrijednosti	Value/ Iznos
Angle of convexity/Kut konveksiteta osealnih struktura	n–A:A–pg	3° ± 5.5°	10.5°
Maxillary plane angle/nagib maksile	n–s:sp–pm	9.5° ± 3.5°	5.4°
Maxillary prognathism angle/ sagitalni položaj maksile	SNA	81° ± 3.5°	84.2°
Mandibular prognathism angle/ sagitalni položaj mandibule	SNB	78.5° ± 3°	78.3°
Skeletal class/ skeletna klasa i	ANB	2.5° ± 2°	5.9°
Y-axis angle/ Kut Y osi	n–s–gn	66.5° ± 3.5°	68.5°
Basal plane angle/ Međučeljusni kut	sp–pm: m–go	25° ± 5°	23.7
Saddle angle/ Kut fleksije kranijalne baze	n–s–ar	123° ± 5°	132.6°
Articular angle/ Zglobni kut	s–ar–go	139.5° ± 6.5°	130.2°
Gonial angle/ Mandibularni kut	m–go–ar	127.5° ± 5°	126.2°
Bjork’s polygon/ Bjorkov poligon		390° ± 5.5°	389.1°
Lower gonial angle/ Donji odsječak mandibularnog kuta	n–go–m	73.5° ± 3.5°	71.6°
Upper gonial angle/ Gornji odsječak mandibularnog kuta	n–go–ar	54.5° ± 4°	54.6°
Upper incisor inclination/ Kut inklinacije gornjih inciziva na bazu maksile	1: sp–pm	111° ± 5.5°	113.2°
Lower incisor inclination/ Kut inklinacije donjih inciziva na bazu mandibule	1: m–go	92° ± 6°	108.9°
Interincisal angle/ Interincizalni kut	1: 1	131.5° + 7.5°	114.2°
Upper incisor to NA line/Položaj gornji inciziva na apikalnu bazu maksile	1: n–A	4.5mm ± 1.5mm	3.9mm
Lower incisor to NB line/ Položaj donjihinciziva na apikalnubazu mandibule	1: n–B	4.5mm ± 1.5mm	7.9mm
Wits appraisal/ Wits procjena		-1.0mm	3.8mm

Treatment

Although there is currently a lack of evidence of a clear link between malocclusion and TMD, we have to consider that the absence of evidence still does not mean evidence of absence. Whenever the treatment protocol includes occlusal changes, a dental intervention must be performed to address the patient's complaints (5). In this case, the treatment involved a multidisciplinary approach with orofacial pain management experts and orthodontists.

Management of temporomandibular pain

The objectives were: i) to minimize pain and ii) to establish a normal function of the lower jaw. The first aim was to immediately ease the amount of pain that the patient was suffering A combination of ibuprofen 400 mg and a low dosage of diazepam 2 mg was prescribed for 14 days. The patient was instructed to restrict the jaw movement to within painless limits. Additionally, she was educated to perform kinesiotherapy on an everyday basis at least 2 times a day. The treatment protocol consisted of self–administered exercises that included passive muscle stretching (the patient was encouraged to open on a straight opening pathway by looking herself in the mirror), and assisted muscle stretching (the patient was instructed to apply gentle force to the elevator muscles with the fingers in order to increase the amount of mouth opening). The patient had been instructed to stop wearing the old soft night guard.

During the first two weeks of pharmacotherapy and kinesiotherapy, the initial evaluation of the patient showed that the pain in the teeth and temporal region did not subside, hence it was decided to further analyze the occlusion in the articulator. This showed that it was possible to establish contacts in the area of the first molars. Following the prior plan of occlusal adjustments, selective grinding was performed to achieve the maximum number of contacts and alleviate symptoms. Additionally, a maxillary stabilization splint was fabricated on a plaster cast in an articulator. It was a hard acrylic splint (Resilit-S, Erkodent, Siemensstrasse 3, 72285 Pfalzgrafenweiler, Germany) with a thickness of 2 mm at the level of the first molar. The clinician adjusted the splint so that the opposing teeth occluded evenly and simultaneously with the occluding surface of the splint in a comfortable and reproducible physiological position (Figure 5).

Figure 5.

Stabilization splint in the patient’s mouth (a); EMG activities of the masticatory muscles during clenching with stabilization splint - more balanced activity of the masticatory muscles was observed (b)

To ensure that muscle activity was balanced when biting on a stabilization splint, the electromyography was performed with the splint in the patient's mouth (Figure 5). The patient was instructed to use the splint only during sleep.

TMD treatment progress

Further follow-up appointments were performed after the 1st, 2nd, and 5th month of wearing the splint. At the 5-month follow-up, the patient reported improvement in symptoms. Pain-free opening amounted to 27 mm intrinsically, while maximum unassisted opening amounted to 29 mm. Occasional pain was still present only during chewing hard food (NPRS=4). Palpation of the masseter muscles did not provoke familiar pain. During the following three months, the patient experienced no recurrence of TMD pain. At the 8-month follow-up, TMD symptoms were almost completely resolved and the patient was ready to start orthodontic therapy.

Orthodontic management

The orthodontic treatment objectives were to: i) correct the open bite, ii) establish correct overjet and overbite, and iii) provide functional and stable occlusion.

When we took into account the patient's financial situation, the only possible treatment was the one that could be covered by a publicly funded healthcare system. That included orthodontic treatment with fixed appliances without using skeletal anchorage which could give us the possibility of posterior molar intrusion followed by mandible autorotation. In this specific case, AOB could have been treated only by camouflage treatment, which included anterior teeth extrusion. Therefore, vertical intermaxillary elastics were used.

Orthodontic treatment progress

Orthodontic treatment with a preadjusted edgewise appliance (Roth prescription .018”) started with the bonding of brackets in the upper arch (0.016'' NiTi archwire). Due to the presence of AOB, the brackets of upper incisors were bonded 0.5 mm cervically to the standard (center of clinical crown) bonding height (11).

After two months, the brackets in the lower arch were bonded and posterior bite blocks were placed on the upper molars to enhance the intrusion (Figure 6).

Figure 6.

Progress of orthodontic therapy: 0.016x 0.022” NiTi wire in the upper archand 0.016” NiTi wire in the lower arch (a); improvement of the anterior open bite due to wearing elastics (b)

After 6 weeks, there was a visible decrease in the AOB, which was due to extrusion of the anterior teeth and possibly intrusion by the posterior bite blocks and rotation of the occlusal plane and mandible. In theory, the stretched muscles place an intrusive force on the posterior teeth, which in turn helps control eruption and permits an upward and forward autorotation of the mandible (12). At this point, the posterior bite blocks were removed and a stainless steel archwire was placed in the upper arch.

When 0.016x 0.022 stainless steel wires were placed in both arches, the patient was instructed to wear vertical intermaxillary elastics 113 g and 3.2 mm (upper canine - lower canine and first premolar) bilaterally.

When the proper overbite was established, the patient was instructed to wear vertical intermaxillary elastics only during the night (Figure 6). Because of the anterior tooth size discrepancy, an interproximal enamel reduction of upper incisors was performed. The patient missed 2 appointments due to the COVID-19 pandemic but she wore the elastics during the whole period.

After 19 months of orthodontic treatment, acceptable occlusion with canines and first molars in class I on both sides was achieved without any TMD symptoms. Brackets were debonded, calculus was removed, and fixed lingual retainers from canine to canine were bonded in both arches (Figure 7). The patient was also instructed to wear Essix retainers during the night.

Figure 7.

Post-orthodontic treatment intraoral (a) and extraoral (b) photographs

Extraorally, the improvement of the slight convex profile of the patient was also visible (Figure 7).

Follow-up appointments during the next 5-month period showed occlusal stability without TMD symptoms.

Discussion

Open bite, with contacts only on the second molars, is an orthodontic anomaly that can cause major problems to the patient and it is quite unlikely that the patient could function in this way without long-term consequences. Contacts present only on the last molars could affect patients’ speech, mastication, and self-esteem. Occlusal forces on such a small area could cause changes in periodontal supportive apparatus and tooth wear (13, 14).

Due to the complexity of the problem presented in this article: i) TMD: pain in the masticatory muscles and restricted opening; ii) abrupt change in occlusion: aesthetic appearance, difficulty eating and pain in the teeth, the treatment plan included a multidisciplinary approach involving dental professionals with two specialties. Even though painful TMD was not caused by an open bite, it is important not to exclude that an open bite contributed to the patient's overall poor mental and physical well-being. Nevertheless, AOB was one of the patient's primary complaints with pain in the molars and esthetic concerns overlapping with the myalgia, therefore it was important to treat both conditions.

Possibilities for AOB treatment in adult patients are maxillary impaction or camouflage therapy by posterior intrusion or anterior teeth extrusion. Since skeletal anchorage was introduced, molar intrusion followed by counterclockwise autorotation of the mandible represents the preferred treatment choice (15). However, Ng et al. concluded that although there are many cases and studies of successfully, non-surgically treated open bites, no evidence-based review has been conducted to determine a better option (16). In some countries including the Republic of Croatia, the usage of temporary anchorage devices (TADs) is not included in the publicly funded healthcare system which is why the only possibility for closing the AOB was anterior teeth extrusion. According to the literature, posterior bite blocks can enhance molar intrusion; therefore we used them in combination with intermaxillary elastics (17).

To date, no causal relationship between open bite and TMD or between TMD and orthodontics has been identified (18, 19). Given that the lack of evidence of the presence of a connection does not always conclude to the absence of that connection entirely, open bite and orthodontic treatment cannot be completely excluded as potential cofactors that might contribute to TMD presence or exacerbation. Dental and medical professionals should always try to calm or eliminate symptoms of TMD before initiating interventions involving irreversible changes in occlusion. It would not be desirable to cause more pain by additional manipulations in the mouth when there are safe, reversible ways to achieve therapeutic success. It is important to note that TMD patients share certain perceptual characteristics that are manifested in increased susceptibility to various changes in the body and thus in occlusion (20-22). Latter might potentially present a problem during orthodontic therapy by both elastics and TADs, hence it is suggested that orthodontic therapy should be closely monitored and performed with caution. Another important issue in the treatment of AOB is the long-term stability of the occlusion with a lack of evidence regarding the stability of different treatment options. Therefore, post-treatment monitoring of patients is very important regardless of the chosen therapy.

When considering the reasons for the sudden opening of the bite in our patient's case it was not possible to confirm the root cause. Since we are not fully aware of the patient's occlusal situation prior to our examination, the initial suspicion was that the bite opened due to the construction of an old soft night guard. Given the splint covered all the teeth, supraeruption of the posterior molars was ruled out. However, the initial data regarding the contacts of lower teeth with the night guard were not recorded, hence we cannot rule out that one of the possible factors that might have contributed to the bite opening was an uneven and unbalanced occlusion. Moreover, there was no control over how much time during the day the patient wore the old night guard. Bereznicki et al. concluded that occlusal changes resulting from inadequately fitted splints are quite common in practice. In their article, they presented guidelines for the treatment of patients fitted with occlusal splints. One of the guidelines states that patients should be regularly monitored and checked for bite changes (8).

Etiologic factors that could cause AOB include sucking habits, mouth breathing, and tongue posture (8). In the case of our patient, the first two factors were excluded. If we eliminate the possibility that the patient just noticed AOB that had existed in her mouth for a longer period of time, because she was more focused on the painful area, the reason for the sudden opening of the bite is probably due to a combination of several complex factors among which could be as follows: old night guard design, tongue thrusting or tongue posture during the rest (23, 24). In theory, an unfavorable habit of holding the tongue between the anterior teeth might lead to a constant lack of occlusal contact between the posterior teeth which could possibly lead to posterior teeth supraeruption. However, this theory is based on speculation and is only an idea that may stimulate clinician interest in further research activities.

Conclusion

In this case, we presented a sudden acute open bite of unknown etiology that occurred after the administration of a soft night guard for the treatment of TMD symptoms. Since the patient presented bilateral myalgia and severe malocclusion it was important to follow a systematic diagnostic and therapeutic workflow. The patient was first treated with combined TMD treatment (stabilization splint, pharmacotherapy, and kinesiotherapy). Once the TMD pain has been resolved, the commencement of fixed orthodontic therapy to treat AOB was considered. The entire treatment lasted for 2 years and 3 months. A 5- month- follow-up showed occlusal stability and only occasional and negligible masticatory muscle pain and headaches.