Pathoses of coronoid process as a cause of mouth-opening restrictions

Shifting the Spotlight From the Mandibular Condyle to the Coronoid Process: A Report of a Unique Case of Trifid Mandibular Coronoid Process

The trifid mandibular coronoid process is an uncommon finding characterized by three projections arising from the mandibular ramus instead of a single triangular coronoid process. Previous authors reported cases of the bifid coronoid process. The authors referred to them as the bifid/second/double coronoid process. This article aims to report a unique case of a trifid coronoid process incidentally detected during radiographic evaluation for implant planning. This article also emphasizes the effectiveness of cone beam computed tomography (CBCT) volume rendering as a valuable tool in demonstrating morphological variations such as the trifid coronoid process. In addition, we discussed possible etiologies for the trifid coronoid process. To the best of our knowledge, this is the first case of the trifid coronoid process.

[Therapeutic strategies for oromandibular dystonia]

Oromandibular dystonia is characterized by tonic or clonic involuntary spasms of the masticatory, lingual and / or muscles in the stomatognathic system. It is often misdiagnosed as craniomandibular dysfunction or psychiatric disease. According to clinical features, the oromandibular dystonia is classified into 6 subtypes (jaw closing-, jaw opening-, tongue-, jaw deviation-, jaw protrusion-, and lip dystonia). There are several treatment methods like botulinum toxin injection, muscle afferent block (injection of lidocaine and alcohol into the masticatory or tongue muscles for blocking muscle afferents from muscle spindle), occlusal splint, and oral surgery (coronoidotomy). Most of patients can be treated successfully according to subtype by combination of these treatments. Special treatment recommendations for each subtype were described in this focus article. Accurate diagnosis and treatment of oral dystonia requires comprehensive knowledge and skills of both oral and maxillofacial surgery and neurology. Therefore, collaboration among these departments is very important.

[Temporo-mandibular ankylosis]

Ankylosis of the temporomandibular joint is defined as a permanent constriction of the jaws with less than 30mm mouth opening measured between the incisors, occurring because of bony, fibrous or fibro-osseous fusion. Resulting complications such as speech, chewing, swallowing impediment and deficient oral hygiene may occur. The overall incidence is decreasing but remains significant in some developing countries. The most frequent etiology in developed countries is the post-traumatic ankylosis occurring after condylar fracture. Other causes may be found: infection (decreasing since the advent of antibiotics), inflammation (rheumatoid arthritis and ankylosing spondylitis mainly) and congenital diseases (very rare). Management relies on surgery: resection of the ankylosis block in combination with bilateral coronoidectomy… The block resection may be offset by the interposition temporal fascia flap, a costochondral graft or a TMJ prosthesis according to the loss of height and to the impact on dental occlusion. Postoperative rehabilitation is essential and has to be started early, to be intense and prolonged. Poor rehabilitation is the main cause of ankylosis recurrence.

Clinical and radiological findings of a bilateral coronoid hyperplasia case

Coronoid hyperplasia (CH) is an infrequent condition that can be defined as an abnormal bony elongation of histologically normal bone. Progressive and painless difficulty in opening the mouth is the main clinical finding of CH. In this case report, the clinical and radiological findings for a 23-year-old male patient with bilateral CH are presented. When plain radiographies are not sufficient for diagnosis and evaluation of the CH, cone-beam computed tomography can be used.

Limited mouth opening of unknown cause cured by diagnostic coronoidectomy: a new clinical entity?

Limited mouth opening is a constant annoyance and can be life-threatening should intubation be needed. The causes are numerous and are categorised as intra-articular or extra-articular, which are often difficult to distinguish. We present what we regard as a new clinical entity - long-standing limited mouth opening of unknown cause - and describe our treatment. Four female patients presented with limited mouth opening and lateral and protrusive movements within normal limits, which were typical of restriction of extra-articular origin. However, the radiological findings were within normal limits, with no visible cause of the restriction. All four were treated by bilateral coronoidectomy that resulted in the immediate return of mouth opening to within normal limits that was preserved over subsequent years. Histopathological examination showed atrophy and degenerative changes in the temporalis band that had been attached to the coronoid, which accounts for the stiffness of the temporalis muscle but does not explain the pathogenesis. In the light of this "diagnostic coronoidectomy" further studies are required to document the underlying pathological changes and to develop more accurate imaging that will enable correct diagnosis in future.

Role of coronoidectomy in increasing mouth opening

Aim:

To evaluate the effectiveness of coronoidectomy in advanced (stage III-IV) oral submucous fibrosis (OSMF) and temporomandibular joint (TMJ) ankylosis.

Materials and Methods:

Five patients clinically diagnosed as grade III/IV OSMF (group 1) and seven patients clinically and radiographically confirmed as TMJ ankylosis (group 2) underwent surgery entailing coronoidectomy in addition to conventional surgical procedures required in both the conditions followed by vigorous mouth opening exercises. The results were evaluated using the interincisal distance at maximum mouth opening as the objective outcome over a follow-up period of 2 months.

Results:

OSMF patients (group I) showed a mean preoperative interincisal opening of 14.40 mm which increased to 24.60 mm after conventional procedures and showed further increment to 35 and 44.80 mm after unilateral and bilateral coronoidectomy, respectively; which was statistically significant (P = 0.043). Follow-up of 2 months showed a gradual increase in mean mouth opening compared to baseline which was also found to be statistically significant (P = 0.043). In TMJ ankylosis patients (group II), preoperative mean mouth opening of 6.71 mm increased to 24.29 mm after conventional procedures, and further to 37.29 mm after unilateral coronoidectomy which was statistically significant (P = 0.018). On subsequent follow-up of 2 months, a gradual increase in mean mouth opening compared to baseline was observed which was statistically significant (P = 0.018).

Conclusion:

Coronoidectomy is an effective adjunct in increasing intraoperative and stabilizing postoperative mouth opening.

Limitation of mouth opening caused by osteochondroma of the coronoid process

BACKGROUND

Osteochondroma at the level of the coronoid process is unusual, causing a slowly progressive facial asymmetry and limitation of mouth opening. Histologically, it is a bone tumor covered by a thin capsule of cartilage. We present a literature review of cases published to date and present a new case in which osteochondroma originating in the coronoid process was associated with the formation of a cyst at the body of the zygoma, necessitating the reconstruction of the body of the zygoma.

STUDY DESIGN

A 55-year-old woman had a bone tumor in the right malar region, producing a limitation in mouth opening. After preoperative computerized tomography, we decided to excise the lesion and pseudocyst with the use of a combined subciliary and coronal approach, reconstructing the body of the zygoma with a cortical chip of calvarian bone.

RESULTS

The patient regained normal mouth opening, without injury to the fronto-orbital branches of the facial nerve and no recurrence of the tumor to date.

CONCLUSIONS

Osteochondroma is a slow-growing tumor that causes progressive facial asymmetry and limitation of mouth opening. The treatment of choice for symptomatic osteochondromas is surgical resection.

Mandibular coronoid hyperplasia in pediatric patients

Bilateral coronoid hyperplasia is a relatively rare condition in the pediatric population and yet may be an unrecognized cause of limited mouth opening in children. There are multiple theories as to the causes of the hyperplasia, which include temporalis hyperactivity, hormonal stimulus, and genetic inheritance. The resulting excess growth of the coronoids results in impingement on the zygomatic processes leading to mandibular hypomobility. The diagnosis is confirmed with plain films and computed tomography scans. Treatment involves bilateral coronoidectomies to relieve impingement on the zygoma. Postoperative physical therapy is crucial for success; the therapy focuses on maintaining the mouth opening achieved at the time of surgery. Outcome reports have been variable despite good physical therapy, suggesting that the exact pathology of the condition is not well understood.

Hyperplasie des Processus coronoideus: Diagnose und Therapie

STUDY GOAL

As it is an unusual and infrequent clinical entity, hyperplasia of the coronoid process is often overlooked or diagnosed too late. The aim of this study was to characterize the morphology, etiology, and clinical picture of coronoid hyperplasia as well as to discuss its diagnosis and treatment.

MATERIALS AND METHODS

All cases of histologically confirmed hyperplasia of the coronoid process treated in our center between 1995 and 2004 were analyzed. Patient data were evaluated with respect to age, gender, clinical symptoms, diagnostic work-up, and treatment. The extracted data were compared to those found in the literature.

RESULTS

The study included 14 new cases and 101 cases already published: 96 with bilateral and 19 with unilateral hyperplasia. At the time of diagnosis, the subjects' mean age was 23.7 years. The patients in Bonn were all treated by coronoidectomy and appropriate physiotherapy. An improvement in mouth opening could be achieved in 86% of our patients.

CONCLUSIONS

In comparison to the somewhat disappointing results of previously published studies with regard to mouth opening and mandibular mobility, our treatment concept seems to offer the possibility for improvement. Our study emphasizes the significance of three-dimensional CT techniques for diagnosis and surgical planning, the superiority of coronoidectomy over coronoidotomy, and the importance of dynamic physiotherapy to prevent postoperative scar formation.

Coronoidotomy as treatment for trismus due to jaw-closing oromandibular dystonia

Oromandibular dystonia is a focal dystonia involving the masticatory and/or tongue muscles. This report describes 2 female patients with jaw-closing dystonia treated by surgical resection of the coronoid process. The patients could not open their mouths due to involuntary jaw-closing muscle contraction. We first treated them by injecting lidocaine and alcohol (muscle afferent block) into the masseter and temporal muscles and then botulinum toxin. However, the trismus improved mildly and transitorily. Therefore, coronoidotomy was done under general anesthesia. The jaw opening increased to 50 mm. Coronoidotomy is useful for patients with jaw-closing dystonia in whom other therapies are ineffective.

Bilateral coronoid hyperplasia in two brothers

Coronoid hyperplasia is a rare condition of unknown aetiology that can occur in both unilateral and bilateral forms. Without radiographic investigation the diagnosis is often missed. Researchers have postulated a familial form of inheritance. This study reports the occurrence of coronoid hyperplasia in two brothers. The parents were unaffected and there are no other siblings. The diagnosis was confirmed with the aid of panoramic radiographs and axial computed tomographic scans with para-sagittal reconstructions which demonstrated enlargement of the coronoid processes and in one case impingement against the zygomatic bone. One brother was successfully treated with a unilateral intra-oral coronoidectomy whilst the other was unsuccessfully treated with a bilateral intra-oral coronoidectomy.

Prolonged mandibular hypomobility patient with a "square mandible" configuration with coronoid process and angle hyperplasia

The objective of this study was the surgical management of chronic severe mandibular hypomobility patients associated with square mandible morphology with coronoid process and angle hyperplasia, and one-year follow-up data is reported. Ten patients were studied. All patients were female and had a history of gradual severe jaw hypomobility. Clinical findings were similar to those of a "closed lock" patient. However, the facial appearance in these patients showed a characteristic square mandible facial configuration. Coronoid process thickening and overgrowth of the mandibular angle was evident in the radiographic findings. Diagnostic imaging scarcely depicted any disk derangement, but a severely limited jaw opening was noted in spite of acceptable excursive jaw movements. Bilateral coronoidotomy or coronoidectomy was done initially, and then masseter muscle stripping via the intraoral approach. After successful reduction of jaw hypomobility, a selective mandibular anglectomy was completed. Physical therapy began within three to five days after the surgery. Postoperatively, all patients were questioned about their jaw function and their subjective assessment of the treatment. Interincisal jaw opening was recorded with a ruler marked in millimeters. Bilateral coronoidotomy or coronoidectomy and masseter muscle stripping were done for all patients; the mandibular anglectomy was performed in seven of the cases at 13 sites. Simultaneous TMJ surgery was done on three joints for three patients. Most patients reported improvement of jaw function, and the patients' subjective assessment revealed an average satisfaction rate of 74.6%. A preoperative mean jaw opening distance of 25.6 mm increased to 36.6 mm postoperatively at a one-year follow-up (p < 0.05). The conclusion was that surgical intervention is indicated when nonsurgical treatment is unsuccessful. Etiology is unknown, but masseter and temporal muscle contracture associated with mandibular coronoid and angle hyperplasia may be a strong component of the pathophysiology.