A 42-year-old Japanese woman with a skeletal class II severe anterior open bite and temporomandibular joint disorder. The pretreatment magnetic resonance imaging of both temporomandibular joints revealed osteoarthritis and anterior disc displacement without reduction ...
Posted July 7,2019 in General Medicine.
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 . The etiology of TMD is suggested to be multifactorial, with malocclusion being a potential risk factor . 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 .
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  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 patients cooperation. Therefore, nowadays, miniplate [9,10,11,12] and miniscrews [13,14,15,16,17,18] 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 [19,20,21,22].
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.
Our patient, a Japanese woman aged 42years and 6months, visited our dental hospital with a chief complaint of impaired masticatory function due to anterior open bite. She also experienced pain in the TMJ while chewing and mouth opening. Her open bite had worsened gradually and she also had tongue thrust. She was previously recommended orthodontic treatment with orthognathic surgery by an orthodontist, but she did not want to undergo the surgery.
Summary of cephalometric measurements
Over jet (mm)
Over bite (mm)
Extraction of the maxillary right and left first premolars
Extraction of the mandibular right and left second premolars.
Insertion of miniscrews into the palatal region and left alveolar bone of mesial part of first molars to intrude the maxillary molars and to avoid anchorage loss.
Correction of crowding and distal movement of anterior teeth.
Extraction of the maxillary left first molar to correct the midline and left molar relationship.
Preparation and insertion of a retainer with tongue crib to avoid tongue thrust.
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 . Numerous treatment methods have been tried for managing DDwoR including manipulation, internal medicine , and surgical correction . Although the exact mechanism of the occlusal splint is not clear , 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 . A 2-year follow-up study suggested that splint therapy effectively improved the maximum mouth opening and alleviated pain associated with DDwoR . The study by Stiesch-Scholzet al. also suggested that stabilization and pivot splints improved maximum mouth opening and reduced TMJ pain related to DDwoR .
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 3months, 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. Schllers 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 . 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 . Hoppenreijset al. reported that Le Fort I osteotomy with or without bilateral SSRO exhibited good skeletal stability in patients with skeletal anterior open bites . In the present case, our patient showed a severe anterior open bite with DDwoR. Because Aghabeigiet al. reported that orthognathic surgery did not have any effect on TMD in patients with anterior open bite , and we wanted to reduce the burden on TMJ induced by orthognathic surgery, an orthodontic camouflage treatment was chosen in this patient. However, Thilanderet al. suggested that orthognathic surgery was effective in improving the symptoms of TMD ; 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 ; hence, this option was chosen in the current study to correct the anterior open bite via orthodontic treatment using miniscrew anchorage. Xunet al.showed that miniscrews can intrude both upper and lower molars by an average of 1.8mm and 1.2mm respectively which leads to a counterclockwise rotation of the mandible . In the present case, the maxillary molars were intruded by 1mm 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 patients 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.
Severe open bite with a class II molar relationship can be treated with miniscrews and molar extraction.
Occlusal splint therapy and orthodontic treatment are useful for managing patients with DDwoR.
The authors have no conflicts of interest directly relevant to the content of this article.