Masticatory muscle tendon-aponeurosis hyperplasia: A new clinical entity of limited mouth opening

Abstract

Limited mouth opening is a common health problem that interferes with eating, makes examination of the oral cavity difficult, and may increase the mortality rate during emergency intubation. Here we introduce a disease designated as masticatory muscle tendon-aponeurosis hyperplasia, which is a new clinical condition of limited mouth opening. Most oral surgeons and dentists are still unaware of this disease condition, thus increasing the risk of incorrect diagnosis as some other disease, such as temporomandibular joint disorder. We will review the clinical features, epidemiology, pathophysiology, etiology, diagnosis, treatment, and prognosis of this disease and also appraise the literature available on the subject.

Keywords: Aponeurosis; Hyperplasia; Limited mouth opening; Masticatory muscle; Tendon.

Figure 1

Clinical characteristics of masticatory muscle tendon–aponeurosis hyperplasia (MMTAH). (A) Photograph of typical square mandibular shape. (B) Cephalometric radiograph of MMTAH showing small gonial angle. (C) Black dotted line displays cephalometric norm of adult Japanese females and black solid line displays typical MMTAH. Both mandibular plane (red solid line) and occlusal plane (blue solid line) in MMTAH tend to show flattening. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Figure 2

Horizontal section in MRI. Overhang of masseter muscle along the anterior border of mandibular ramus (yellow arrow). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Figure 3

Histological analysis of MMTAH . (A) Hematoxylin and eosin staining of tendon tissues. (B) Element mapping of tendon tissues. Silicon is indicated by red arrow. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Figure 4

Intraoral palpation along the anterior border of the masseter muscle.

Figure 5

Surgical procedure. (A) Tendon of the temporal muscle. (B) Excised coronoid process.

Figure 6

Tendon and aponeurosis in the first postoperative year . (A) Before surgery. (B) After surgery (1 year later). TR, 3800.00; TE, 13.00 (A and B). (C) Before surgery. (D) After surgery (1 year later). TR, 4420.00; TE, 87.00 (C and D).