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COPYRIGHT 2009 Chroma, Inc.ABSTRACT: A case of unilateral coronoid hyperplasia successfully treated by corenoidotomy with prolonged postoperative physiotherapy and reveal the postoperative radiographic changes between the sectioned part of the coronoid process and the mandibular ascending ramus is described. The patient was a 28-year-old man whose maximum mouth opening was 30 mm. A coronoidotomy of the left coronoid process was performed. Nine days after surgery, the patient started physiotherapy with a HU-OSr appliance. After coronoidotomy and physiotherapy, the maximum mouth opening had increased to 43 mm. Radiographic follow-up showed that the coronoid process apparently united with the mandibular ascending ramus, with moderate dislocation and inclination posteriorly. In the case presented, an intraoral coronoidotomy with postoperative physiotherapy for treatment of coronoid process hyperplasia allowed satisfactory and stable results in the correction of coronoid-malar interference.
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In patients with coronoid process hyperplasia, which presents essentially a mechanical problem such as limited mouth opening, a surgical treatment with prolonged postoperative physiotherapy is performed. The surgical treatment for coronoid process hyperplasia is correction of the coronoid-malar interference by a coronoidectomy or simply coronoidotomy. Gerbino, et al., (1) reported that coronoidotomy was performed intraorally by an osteotomy at the base of the coronoid process in five patients and that this approach notably reduces the need for bone exposure and consequent surgical trauma compared to the coronoidectomy. With respect to postoperative physiotherapy, several devices are used for maintenance of sufficient interincisal distance. (1-3) Previously, a mouth-opening exerciser (HU-OS II) (4-6) was introduced for postoperative mouth-opening exercises in patients with severe trismus due to temporomandibular joint ankylosis after maxillectomy. The exerciser is available for increasing the mouth opening range without help postoperatively.
A case of unilateral coronoid hyperplasia is described that was successfully treated by coronoidotomy with prolonged postoperative physiotherapy, using a HU-OS II appliance and revealed the postoperative radiographic changes between the sectioned part of the coronoid process and the mandibular ascending ramus.
Case Report
A 28-year-old man was referred for evaluation of a persistent limited mouth opening. The patient first noticed the difficulty opening his mouth when he was 15 years old. He consulted a dentist and was given a diagnosis of temporomandibular joint disorder. There was no history of maxillofacial injury or familial occurrence of similar problems.
Clinical examination revealed limited mouth opening but no temporomandibular joint pain and no masticatory muscle tenderness. The maximum mouth opening was 30 mm. Left and right excursions were seven mm each and protrusive excursion was six mm. There was no dentofacial abnormality.
Orthopantomography showed the right coronid processes with normal length and the elongation of the left coronid processes (Figure 1). Computed tomography demonstrated the contact of the left zygomatic bone and the coronoid process in the open mouth position. Bone formation at the contact point on the posterior surface of the left zygomatic bone was observed (Figure 2 A-B). A diagnosis of left coronoid process hyperplasia was confirmed using the characteristic radiographic and clinical findings.
With the patient under general anesthesia, a coronoidotomy of the left coronoid process was performed intraorally by an osteotomy at the base of the coronoid process. A horizontal osteotomy was made with a Lindemann bur from the sigmoid incision to the anterior aspect of the ascending ramus (Figure 3A). The maximum mouth opening was 50 mm immediately after the osteotomy. The sectioned coronoid was not removed because there was no interference with enforced mandibular movement (Figure 3B).
Nine days after surgery, the maximum mouth opening was 33 mm. The patient started physiotherapy with a mouth-opening exerciser (HU-OS II) (Figure 4). The patient used the mouth-opening exerciser to do 100 consecutive openings using the exerciser with no other assistance--one opening per second, 100 seconds total. This exercise was done twice a day, once in the morning and once at night. Thirty days after surgery, the maximum mouth opening had increased to 40 mm, and at the three month follow-up, it had stabilized at 43 mm. The mechanical physiotherapy was then interrupted. At the 15 month follow-up, the maximum mouth opening range was still 43 mm, with good protrusion and lateral mandibular excursion, no displacement of the mandible, and no pain in the temporomandibular joint region.
Radiographic follow-up showed that the coronoid process apparently united with the mandibular ascending ramus, with moderate dislocation and inclination posteriorly (Figures 5 and 6).
Discussion
The treatment of coronoid process hyperplasia, which presents essentially a mechanical problem, is primarily surgical. In a coronoidectomy, the ascending ramus of the mandible is exposed as far as the top of the coronoid process, and then the temporalis muscle is detached from the coronoid. The entire coronoid process is removed. Change in muscle activity with detachment of the temporalis muscle and postoperative fibrosis with removal of the coronoid may lead to displacement of the mandible and the other disappointing results. (1,2) However, Gerbino, et al., (1) described five patients with coronoid process hyperplasia, who were successfully treated by coronoidotomy, and reported that this approach notably reduces the need for bone exposure and consequent surgical trauma compared to the coronoidectomy. Furthermore, this technique without removal of the coronoid process also reduces the organization of a postsurgical hematoma, with consequential fibrosis at the site of the operation. In the current patient, a simple coronoidotomy was performed intraorally by an osteotomy at the base of the coronoid process. The favorable outcome of the coronoidotomy in this case may have been because there is less postsectioned fibrosis with this procedure and because the sectioned part of the coronoid can position itself and consolidated posteriorly.
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