Background
Temporomandibular joint disorder (TMD) is a comprehensive term and is characterized by the clinical presentation of: pain in the masticatory musculature and in the temporomandibular joint (TMJ), limited range of mandibular movement, and clicking or crepitus during jaw movement [
1]. The etiology of TMD is suggested to be multifactorial, with malocclusion being a potential risk factor [
2]. Numerous treatment methods have been described for anterior disc displacement without reduction (DDwoR) of TMJ. Among them, orthodontic treatment along with an occlusal splint is considered quite effective for managing TMD with anterior disc displacement [
3].
In open bite cases, overgrowth of the maxillary and mandibular posterior dentoalveolar heights is often observed [
4,
5], and cases of skeletal class II open bite with a steep mandible are more difficult to treat because of the increased vertical facial height [
6,
7]. Therefore, high-pull headgear with a transpalatal arch [
8] is traditionally used to correct the over-erupted posterior molar regions. However, this approach of reducing the posterior dentoalveolar height using headgear is not always effective as the treatment outcome is greatly influenced by the patient’s cooperation. Therefore, nowadays, miniplate [
9‐
12] and miniscrews [
13‐
18] are used currently for absolute anchorage. Cases of anterior open bite are often associated with TMD, and only a few reports describe the management of open bite and TMD by molar intrusion using miniscrew anchorage [
19‐
22].
In this case report, we describe the outcome of severe skeletal class II open bite treated using miniscrews along with extraction of the four premolars and the left maxillary first molar.
Discussion
The TMJ disc in patients with DDwoR is shifted anteriorly and cannot revert to the correct position during jaw movement, resulting in TMJ pain and limitation of jaw movement [
23]. Numerous treatment methods have been tried for managing DDwoR including manipulation, internal medicine [
24], and surgical correction [
25]. Although the exact mechanism of the occlusal splint is not clear [
26], it is one of the important and frequently used treatment modalities. It has been suggested that splint therapy may reduce overloading on the TMJ and relieve the masticatory muscles [
24]. A 2-year follow-up study suggested that splint therapy effectively improved the maximum mouth opening and alleviated pain associated with DDwoR [
27]. The study by Stiesch-Scholz
et al. also suggested that stabilization and pivot splints improved maximum mouth opening and reduced TMJ pain related to DDwoR [
28].
In this case, our patient was diagnosed as having DDwoR via MRI, and a stabilization occlusal splint was used before orthodontic treatment to reduce the TMJ pain associated with masticatory movement. As a result of splint therapy for 3 months, the TMJ pain associated with chewing and mouth opening was relieved. There were no symptoms of TMD during the active orthodontic treatment and the retention period. Schüller’s view also revealed that there was no change of condyle shape and jaw movement before and after orthodontic treatment. However, a recent study showed that splint therapy can be continued during the first several months with orthodontic treatment by adjustment of the splint according to the tooth movement [
29]. So, simultaneous recovery in the TMJ with the orthodontic treatment might be achieved without delay of the treatment in this case.
Anterior open bite can occur following overgrowth of the posterior dentoalveolar heights in the maxilla and mandible. Orthognathic surgery is considered effective in improving occlusion and facial profile in patients with severe skeletal open bite along with excessive lower facial height. In such cases, maxillary surgical impaction is often applied for the mandibular counterclockwise rotation. Le Fort I and bilateral sagittal split ramus osteotomy (SSRO) reportedly offer successful and stable outcomes in patients with skeletal open bite [
30]. Hoppenreijs
et al. reported that Le Fort I osteotomy with or without bilateral SSRO exhibited good skeletal stability in patients with skeletal anterior open bites [
31]. In the present case, our patient showed a severe anterior open bite with DDwoR. Because Aghabeigi
et al. reported that orthognathic surgery did not have any effect on TMD in patients with anterior open bite [
32], and we wanted to reduce the burden on TMJ induced by orthognathic surgery, an orthodontic camouflage treatment was chosen in this patient. However, Thilander
et al. suggested that orthognathic surgery was effective in improving the symptoms of TMD [
33]; study of the role of orthognathic surgery in the management of TMD should be progressed.
A previous study showed that molar intrusion by miniscrew anchorage was an effective treatment option in patients with TMD who have horizontal open bite with a steep mandible [
20]; hence, this option was chosen in the current study to correct the anterior open bite via orthodontic treatment using miniscrew anchorage. Xun
et al. showed that miniscrews can intrude both upper and lower molars by an average of 1.8 mm and 1.2 mm respectively which leads to a counterclockwise rotation of the mandible [
34]. In the present case, the maxillary molars were intruded by 1 mm and FMA decreased by 0.8°. However, since the change was negligible, improvement of the overbite was brought about by extrusion of both maxillary and mandibular incisors.
A right shift in the maxillary dental midline was noted after the premolar extraction space was closed, while the left canine and molar relationship remained class II. Hence, the maxillary left first molar was extracted. In such cases, the third molar is removed and the second and first molars are moved distally to achieve a class I molar relationship. However, molar distalization requires more time and out patient’s left first molar was pulpless and was restored by a full-cast crown. Moreover, the left third molar was intact and the size was appropriate. Hence, it was decided to extract the first molar to correct the midline and left molar relationship. As a result, a good intercuspal relationship with a normal overjet and overbite were achieved and the maxillary and mandibular midlines coincided. However, since long-term stability of open bite correction depends on many factors, such as tongue thrust, periodic checkups and examinations of the TMJ are necessary for this patient.
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