Bony ankylosis of the temporomandibular joint: follow-up of 70 patients treated with arthroplasty and acrylic spacer interposition

This paper presents the author's experience with interpositional arthroplasty using an acrylic cylinder in 70 cases of bony ankylosis of the temporomandibular joint. Ankylosis followed trauma in all but one patient. The diagnosis was established when restriction of mouth opening was associated with roentgenologic evidence of deformation of the condyle, obliteration of the joint space, and abnormal bone formation in and around the joint. The pathologic changes were classified into four types depending on severity, and each type influenced the treatment. Surgical treatment included creation of a transversely elliptical gap between the two bony components of the joint using a neurosurgical burr and perforator and a chisel through a preauricular approach and interposition of an acrylic cylinder. This maintained the gap, facilitated movement, and encouraged nonunion. The results following a long follow-up of 2 to 10 years showed uniformly good results with a range of mouth opening varying from 2 to 5 cm. Only three bilateral cases recurred and two others had a limited range of mouth opening, with interincisor distance varying from 2 to 2.5 cm.     

Unpredictable growth pattern of costochondral graft.

Costochondral grafts have gained increasing popularity in reconstruction of the temporomandibular joint and condyle in children. This is a report on the long-term follow-up of eight adolescent patients who underwent reconstruction of the temporomandibular joint and ramus for correction of hemifacial microsomia or trauma-related temporomandibular joint ankylosis during varying periods of growth. Six patients had hemifacial microsomia, and two suffered from posttraumatic temporomandibular joint ankylosis. Average follow-up was 80.4 months. Four patients had excessive growth of the graft, one patient had suboptimal growth, and three patients had no growth. In addition, one patient had undergone four procedures for significant graft overgrowth. Based on this study and review of the literature, we have concluded that the growth pattern of the costochondral graft is extremely unpredictable, ankylosis is a common problem following a temporomandibular joint reconstruction with costochondral graft, and mandibular overgrowth on the grafted site can actually be more troublesome than the lack of growth. Furthermore, maxillary growth is proportionately influenced by vertical mandibular growth of the graft, while the horizontal maxillary growth is not altered. Ankylosis is a result of ossification of the cartilaginous portion and the three-dimensional graft overgrowth, aggressively extending beyond the cartilage graft boundary. Based on this study, we recommend that this procedure be performed only on severe deficiencies. Adequate amounts of soft tissue should be retained between the skull base and the graft, and we further recommend harvesting the graft from the fourth or fifth rib, which may reduce the potential for overgrowth.(ABSTRACT TRUNCATED AT 250 WORDS)     

Free perichondrial grafting in the treatment of temporomandibular joint ankylosis. Preliminary report

We have operated on 6 cases of temporomandibular joint ankylosis, resecting a small amount of bone to create a false joint and then covering the two joint surfaces with sheets of perichondrium (autogenous, from the ribs). The perichondrium forms new cartilage on the joint surfaces, and the early results are encouraging. Only one of these cases was operated upon more than one year ago. He has an excellent result and this case is reported on in detail.     

Simultaneous total correction of temporomandibular ankylosis and facial asymmetry

Ankylosis of the temporomandibular joint not only prevents mouth opening and chewing, but also affects the growth and position of the mandible. This produces progressive facial distortion with devastating psychosocial effects compounding the already difficult problem of not being able to open the mouth. Over the past 6 years, 18 patients in Canada and Taiwan were treated by excision of a large block of bone at the ankylosis and repositioning of the jaw, with the addition of osteotomies as necessary to produce a symmetrical face with good occlusion. Bilateral cases were treated at one operation in a similar way. The temporomandibular joint and absent ramus were constructed with a costochondral graft taken from the opposite chest. Some patients were treated with intermaxillary fixation for 8 weeks, while others had no fixation, but there was no difference in the effectiveness of correction of the ankylosis.     

Mandibular distraction in temporomandibular joint ankylosis

Condylar damage during childhood can produce ankylosis and alteration of the mandibular growth. In case of unilateral ankylosis occurring in early childhood, a mandibular hypoplasia of the affected side may develop. The patients have limitation of mouth opening, facial asymmetry, and chin deviation toward the affected side. The aims of this study are to show the use of distraction osteogenesis in mandibular hypoplasia associated with ankylosis and to present our experience with a new therapeutic option for the treatment of mandibular hypoplasia with unilateral ankylosis in the childhood consisting of the association of arthroplasty to treat the ankylosis and mandibular distraction to correct the facial asymmetry, both accomplished in the same surgical procedure. From November of 1996 to November of 1997, three male patients aged 2, 7, and 13 years with mandibular hypoplasia and ankylosis were treated by distraction osteogenesis. An arthroplasty consisting of the resection of the ankylotic block and interposition of a temporalis muscle flap, plus coronoidectomy was done in two of them and mandibular distraction was done in all three patients. Articular functional rehabilitation began on the first postoperative day. Mandibular distraction began on the fifth postoperative day with a rate of 1 mm per day, ending when the facial symmetry was achieved. From the first postoperative day, an increase in the mouth opening was achieved; this increase continued until ending the distraction. The average duration of distraction was 22 days. Average duration of consolidation was 6 weeks. Oral opening increased from 10 mm to 35 mm in the 7-year-old patient, from 9 mm to 27 mm in the 2-year-old patient, and from 14 mm to 38 mm in the 13-year-old patient. To date, oral opening and facial symmetry persist. Osseous mandibular distraction together with arthroplasty offers an excellent new alternative for treatment of patients with mandibular hypoplasia and associated ankylosis, with minimal morbidity and complications.     

The use of Teflon in orbital floor reconstruction following blunt facial trauma: a 20-year experience

A myriad of materials have been used for reestablishing continuity of the orbital floor following blunt facial trauma. Traditionally, autogenous grafts have been the material of choice for orbital floor reconstruction; however, alloplastic materials have gained popularity because of their availability and ease of use. A large clinical experience with long-term treatment results has never been reported for any substance used in orbital floor reconstruction. The purpose of this study was to review our long-term treatment results using Teflon for orbital floor reconstruction following blunt trauma, with emphasis on the incidence of infection, extrusion, and implant displacement. This report presents a 20-year review of 230 Teflon implants for reconstruction of traumatic orbital floor defects. With a mean follow-up period of 30 months, there was only one implant infection and no complications of extrusion or implant displacement. These findings support the use of Teflon as a safe and effective material for the reconstruction of orbital floor defects following blunt facial trauma.     

Squamous cell carcinoma of the oral mucosa after release of submucous fibrosis and bilateral small radial forearm flap reconstruction

Oral submucous fibrosis is a collagen disorder that affects the submucosal layer of the upper digestive tract. The major cause is the habit of betel quid chewing, which is common in central, southern, and southeast Asia. The progressive and irreversible course of disease results with trismus, dysphagia, xerostomia, and rhinolalia. The most serious complication of this disorder is the development of oral carcinoma, and the incidence in different series varies from 1.9 to 10 percent. A sufficient mouth opening can be achieved by complete release of fibrotic tissue, and coronoidectomy and temporal muscle myotomy when needed, and reconstruction of the resultant defect can be best achieved by microsurgical free-tissue transfer because of the discouraging results with skin grafting or local flaps. From April of 1997 to May of 2001, a total of 26 patients received reconstructive surgery with small radial forearm flaps after release of submucous fibrosis with or without temporalis muscle myotomy and coronoidectomy. All patients were men, with a mean age of 40.1 years (range, 18 to 62 years) and all had a history of betel nut chewing ranging from 8 to 40 years. The interincisal distance ranged from 5 to 29 mm, with a mean of 15 mm, before operation. After the release procedure, the interincisal distance increased to 40 mm (range, 35 to 50 mm). At a follow-up period of 3 to 48 months, the interincisal distance was a mean of 35 mm (range, 18 to 57 mm), with an average increase of 20 mm compared with the preoperative distance. During follow-up, three patients developed squamous cell carcinoma of the oral cavity 24 to 36 months after submucous fibrosis release. Two of them occurred in the release site and the other one occurred at the soft palate. Oral cancer occurred in three of 13 patients who had received release of submucous fibrosis and who were followed for longer than 2 years (range, 24 to 48 months), which means that 23 percent of these patients developed squamous cell carcinoma of the intraoral mucosa. High risk of cancer occurrence strongly indicates the importance of an earlier and more aggressive surgical approach toward submucous fibrosis, and long-term follow-up on a regular basis. The purpose of an early and aggressive approach to submucous fibrosis is to provide a good quality of life to the patient by improving oral hygiene and oral intake quality and at the same time to obtain a sufficient mouth opening, which is mandatory for the inspection of the excision site and the remaining oral mucosa during follow-up.     

Correction of extracapsular temporomandibular joint ankylosis with a cervical subcutaneous pedicle flap

A new method of correcting extracapsular temporomandibular joint ankylosis with a cervical subcutaneous pedicle flap is described. In this procedure, a cervical subcutaneous pedicle flap with or without platysma is introduced into the oral cavity through a tunnel to repair the defect after the buccal scar is excised and the normal oral opening is restored. Sixteen consecutive patients underwent the surgery, and good results were obtained.     

Age-related osteo-arthrotic degeneration of the temporomandibular joint in the mouse

The light-microscopic and ultrastructural characteristics of the temporomandibular joints (TMJs) of female STR/IN mice, aged from 3 to 12 months, were studied. Every TMJ of an adult mouse starts to degenerate in early adulthood and subsequently suffers from osteo-arthrosis. Ageing of the TMJ is characterized by thinning out of its cartilaginous components. The chondrocytes are no longer distributed regularly in the ground substance but form clusters. Cracks and fissures invade the condylar cartilage and lead to the formation of cartilage islands, which finally become loose as free bodies in the lower joint chamber and joint capsule. The lower joint chamber diminishes, but no ankylosis is observed. Ultrastructurally, the number of vesicles around the degenerated chondrocytes increases. Aged chondrocytes contain more lysosomes. The condylar surface becomes irregular and reveals microscars. Its surface is covered by an electron-dense fine granular material, considered to be built up by proteoglycans. Compared to the male ICR mouse, the osteo-arthrotic destruction of the cartilage, the subchondral sclerosis and the deformation of the underlying bone exhibit only minor states in the female STR/IN mouse. Concerning the aetiology and pathogenesis, the very early degeneration of the mostly unloaded TMJ seems to be based on a genetically altered composition of the articular cartilage, possibly due to failing articular chondrocyte responses to stimuli connected with degeneration and repair.     

Framework growth after reconstruction for microtia: is it real and what are the implications?

Historically, fashioning an auricle for a patient born with microtia has been one of the most challenging endeavors in the repertoire of reconstructive surgeons. Despite many ideas advanced on types of materials for the auricular framework, the hands-down favorite and today's medium of choice is autogenous costal cartilage. A subject that remains up for discussion, however, is the question of growth potential in these cartilaginous frameworks. Popularization of the surgical technique for auricular reconstruction has led to much bandying about of opinions on this very important question of growth. Although previous reports allude to the probability of an increase in auricular size after reconstruction, this report is the first to document changes in auricular size with measurements taken directly from patients at the time of graft implantation and during subsequent long-term follow-up. The goals of this study are to define the behavior of the autogenous framework after reconstruction of the microtic auricle. This information serves to clarify the issue of proper framework sizing and to make evident the early age at which reconstruction can begin.The records of patients who underwent costal cartilage auricular reconstruction for grade III microtia between 1990 and 1996 were reviewed, and a cohort of 10 patients was chosen for inclusion based on availability for follow-up and lack of any interval modifications of their cartilaginous framework. The average age was 6.7 years, and the average time interval from initial reconstruction to follow-up was 3.2 years. Measurements of the auricular framework height and width were taken at implantation and at time of final follow-up, and measurements were recorded of the normal ears of patients with unilateral microtia. The mean auricular size was examined for significance of interval change using the two-sample Student's t tests, assuming unequal variances.The results revealed an average height increase of 5 mm (10.4 percent) in the study population. Auricular width changes averaged 2.75 mm (7.02 percent). Growth trends revealed a distinct tendency toward increasing auricular framework size over time, with slowing as patients neared adolescence. Comparison of the reconstructed auricle to the normal ear of each patient with unilateral microtia showed that the reconstructed ear paralleled the growth of the normal side, with no statistically significant differences in height or width at follow-up.This is the first report of auricular framework behavior based on patients having direct measurement of their framework initially and in long-term follow-up. This patient sample underscores a clear pattern of growth in the reconstructed auricles paralleling that of the normal ears. The implications of this finding are important in that the initial oversizing of the framework becomes unnecessary. Moreover, the decision as to age at initial reconstruction is not affected by anticipated growth rates.     

Tissue engineering: revolution and challenge in auricular cartilage reconstruction

External ear reconstruction for congenital deformity such as microtia or following trauma remains one of the greatest challenges for reconstructive plastic surgeons. The problems faced in reconstructing the intricate ear framework are highly complex. A durable, inert material that is resistant to scar contracture is required. To date, no material, autologous or prosthetic, is available that perfectly mimics the shapely elastic cartilage found in the ear. Current procedure involves autologous costal cartilage that is sculpted to create a framework for the overlying soft tissues. However, this is associated with donor-site morbidity, and few surgeons worldwide are skilled in the techniques required to obtain excellent results. Various alloplastic materials have therefore been used as a framework. However, a degree of immunogenicity and infection and extrusion are inevitable, and results are often disappointing. Tissue-engineered cartilage is an alternative approach but, despite significant progress in this area, many problems remain. These need to be addressed before routine clinical application will become possible. The current tissue-engineered options are fragile and inflexible. The next generation of auricular cartilage engineering is promising, with smart materials to enhance cell growth and integration, and the application of stem cells in a clinical setting. More recently, the authors' team designed the world's first entirely synthetic trachea composed of a novel nanocomposite material seeded with the patient's own stem cells. This was successfully transplanted in a patient at the Karolinska Hospital in Sweden and may translate into a tissue-engineered auricle in the future.     

Development of a computational technique to measure cartilage contact area

Computational measurement of joint contact distributions offers the benefit of non-invasive measurements of joint contact without the use of interpositional sensors or casting materials. This paper describes a technique for indirectly measuring joint contact based on overlapping of articular cartilage computer models derived from CT images and positioned using in vitro motion capture data. The accuracy of this technique when using the physiological nonuniform cartilage thickness distribution, or simplified uniform cartilage thickness distributions, is quantified through comparison with direct measurements of contact area made using a casting technique. The efficacy of using indirect contact measurement techniques for measuring the changes in contact area resulting from hemiarthroplasty at the elbow is also quantified. Using the physiological nonuniform cartilage thickness distribution reliably measured contact area (ICC=0.727), but not better than the assumed bone specific uniform cartilage thicknesses (ICC=0.673). When a contact pattern agreement score (s_agree) was used to assess the accuracy of cartilage contact measurements made using physiological nonuniform or simplified uniform cartilage thickness distributions in terms of size, shape and location, their accuracies were not significantly different (p>0.05). The results of this study demonstrate that cartilage contact can be measured indirectly based on the overlapping of cartilage contact models. However, the results also suggest that in some situations, inter-bone distance measurement and an assumed cartilage thickness may suffice for predicting joint contact patterns.     

Differences in loading of the temporomandibular joint during opening and closing of the jaw

Kinematics of the human masticatory system during opening and closing of the jaw have been reported widely. Evidence has been provided that the opening and closing movement of the jaw differ from one another. However, different approaches of movement registration yield divergent expectations with regard to a difference in loading of the temporomandibular joint between these movements. Because of these diverging expectations, it was hypothesized that joint loading is equal during opening and closing. This hypothesis was tested by predicting loading of the temporomandibular joint during an unloaded opening and closing movement of the jaw by means of a three-dimensional biomechanical model of the human masticatory system. Model predictions showed that the joint reaction forces were markedly higher during opening than during closing. The predicted opening trace of the centre of the mandibular condyle was located cranially of the closing trace, with a maximum difference between the traces of 0.45 mm. The hypothesis, postulating similarity of joint loading during unloaded opening and closing of the jaw, therefore, was rejected. Sensitivity analysis showed that the reported differences were not affected in a qualitative sense by muscular activation levels, the thickness of the cartilaginous layers within the temporomandibular joint or the gross morphology of the model. Our predictions indicate that the TMJ is loaded more heavily during unloaded jaw opening than during unloaded jaw closing.     

Distraction osteogenesis in correction of micrognathia accompanying obstructive sleep apnea syndrome

To evaluate the effect of distraction osteogenesis in correction of micrognathia accompanying obstructive sleep apnea syndrome, a total of 28 patients with different severities of obstructive sleep apnea syndrome underwent mandibular distraction osteogenesis. A total of 51 distraction devices were placed for bilateral distraction in 23 patients and for unilateral distraction in five patients. The mean age of patients was 21.2 years (range, 3 to 60 years). Eleven patients had micrognathia accompanying obstructive sleep apnea syndrome secondary to bilateral temporomandibular joint ankylosis, and 10 patients had micrognathia accompanying obstructive sleep apnea syndrome secondary to unilateral temporomandibular joint ankylosis. Three patients had developmental micrognathia accompanying obstructive sleep apnea syndrome. The other four patients had micrognathia and concomitant obstructive sleep apnea syndrome induced by trauma, infection, or tumor resection. Each patient had been evaluated preoperatively and postoperatively with cephalometry and polysomnography. Mandible advancement ranged from 9 to 30 mm (average, 20.4 mm) and was successfully achieved after distraction. Fine new bone formed in the distraction gap when the distraction devices were removed 3 to 4 months after distraction was completed. No infection or other complications occurred in any patients. Complete curative effects were achieved in nine severe, six moderate, and eight mild obstructive sleep apnea syndrome patients after distraction, and the other five patients had been improved to the mild level. After distraction was completed, the posterior airway space was increased on average from 4.6 mm to 12.5 mm and the sella-nasion-point B angle was increased on average from 66 degrees to 75 degrees on cephalometric studies. The polysomnographic examination showed that the apnea hypopnea index was lowered on average from 58.0 to 3.15, and the lowest oxygen saturation was increased on average from 77 percent to 90.3 percent after distraction was completed. The follow-up period was 3 to 61 months (average, 18.1 months). The curative effect was stable and no relapse occurred. Therefore, the authors conclude that mandibular distraction osteogenesis is an effective method for correcting micrognathia accompanying obstructive sleep apnea syndrome. Compared with other current routine surgical procedures, it has many advantages, such as low risk, simple manipulation, high curative rate, low relapse rate, and stable result. It is presently the most effective method for the treatment of this difficult and complicated disorder.     

Comparison of the biological activities of high-density porous polyethylene implants and oxidized regenerated cellulose-wrapped diced cartilage grafts

The use of alloplastic materials in plastic surgery has become more extensive with advancement of autogenous-tissue reconstruction techniques for the repair of defects, tissue augmentation, and the stabilization of bones. An ideal alloplastic material should be nonallergenic, noncarcinogenic, sterilizable, and easy to shape and should not cause rejection. Alloplastic material used for tissue augmentation should have a low rate of resorption and distortion. High-density porous polyethylene implants (Medpor) have been used widely and successfully for tissue augmentation. The Turkish Delight is a material composed of diced cartilage grafts wrapped in oxidized regenerated cellulose (Surgicel). Its indications are similar to those of the Medpor implant, and an additional donor site is usually not needed. Both materials are used in the same anatomical locations, especially for augmentation. Therefore, the authors evaluated the long-term stability of and suitable anatomical sites for these materials. Medpor implants or Turkish Delights were placed subperiosteally or subfascially in 10 young rabbits, and the resultant changes were evaluated 16 weeks after the operation by macroscopy and histopathology. Changes in projections were measured with an ocular micrometer. Medpor implants were neither resorbed nor distorted when placed subperiosteally or subfascially, and were highly stabilized by the surrounding tissues. Turkish Delight also enabled tissue augmentation, but had a significantly higher rate of resorption compared with the Medpor implant and was loosely bound to the surrounding tissue. The Turkish Delight was less resorbed and better fixed to adjacent tissues when placed subperiosteally than when placed subfascially.     

Gap Arthroplasty versus Interpositional Arthroplasty for Temporomandibular Joint Ankylosis: A Meta-Analysis

Gap arthroplasty (GA) and interpositional arthroplasty (IA) are widely used for the treatment of temporomandibular joint ankylosis (TMJA). However, controversy remains as to whether IA is superior to GA. PubMed, EMBASE, the Cochrane Library, the Web of science and the China National Knowledge Infrastructure were searched for literature regarding these procedures (published from 1946 to July 28, 2014). A study was included in this analysis if it was: (1) a randomized controlled trial or non-randomized observational cohort study; (2) comparing the clinical outcomes between GA and IA with respect to the maximal incisal opening (MIO) and reankylosis; (3) with a follow-up period of at least 12 months. The methodological quality of the included studies was evaluated according to the Newcastle-Ottawa Scale Eight non-randomized observational cohort studies with 272 patients were included. All the statistical analyses were performed using the RevMan 5.3 and Stat 12. The pooled analysis showed no significant difference in the incidence of reankylosis between the IA group (13/120) and the GA group (29/163) (RR= 0.67, 95% CI=0.38 to 1.16; Z=1.43, p=0.15). The IA group showed a significantly larger MIO than the GA group (MD=1.96, 95% CI=0.21 to 3.72, Z=2.19, p=0.03, I²=0%). In conclusion, patients with TMJA could benefit more from IA than GA, with a larger MIO and a similar incidence of reankylosis. IA shows to be an adequate option in the treatment of TMJA based on the results of maximal incisal opening.     

Kinematic study of the mandible using an electromagnetic tracking device and custom dental appliance: introducing a new technique

The purpose of this study is to introduce a new technique for recording the kinematics of the temporomandibular joint and incisors, using an electromagnetic tracking device and custom dental appliance. Five normal subjects took part in this kinematic study (4 females, 1 male, mean age of 34.8 years). Subjects' mandibular motion during maximal opening tasks were recorded on two different days and linear distance (LD) (i.e., the LD between the start and end position) and curvilinear path (CP) (i.e., the curvilinear distance along the curve between the start and end position) were calculated for the lower incisor landmark and both condyles in the sagittal plane (in mm). In the present study, the range of incisal movements (LD: 34.9 to 54.3 mm, CP: 36.5 to 60.3 mm) and that of condylar movements (LD: 7.5 to 25.3 mm, CP: 10.6 to 27.6 mm) in the sagittal plane during opening are in the normal range compared to the previous literature. The ability of subjects to reproduce the same motion between the two sessions was also calculated. Differences due to trial sessions and different repetitions within a session were negligible, indicating that the method can be used to assess changes between testing conditions in healthy subjects, and patients pre- and post-operatively.     

A cadaveric analysis of the ideal costal cartilage graft for Asian rhinoplasty

Augmentation rhinoplasty of the Asian nose may be effectively accomplished with alloplastic materials. However, certain circumstances mandate the use of autologous grafts (e.g., dorsal augmentation that exceeds 8 mm and patient intolerance of alloplastic implants). Septal and auricular cartilages are inadequate for dorsal augmentation of the Asian nose. The use of costal cartilage for autologous augmentation in select Asian patients has proven to be a reliable method in more than 500 operative cases during a 10-year period. This study was designed to evaluate the ideal costal cartilage graft for augmentation rhinoplasty. Forty-two preserved cadavers were studied for the relationship of the individual rib cartilages to the surrounding tissue and for the length and caliber of each costal cartilage. The seventh rib was found to be the ideal rib graft by virtue of its safe location and overall size for grafting. The seventh rib is situated over the abdominal cavity, so the risk of pneumothorax is insignificant. The internal thoracic artery and vein descend in close apposition behind the first to sixth ribs but begin a course medial to the ribs inferior to this point, and therefore vascular injury during seventh-rib harvesting is unknown. The seventh rib also provides the greatest overall available length (90.7 mm, right; 89.6 mm, left) and thickness (17.6 mm, right; 17.5 mm, left). Despite the more conspicuous location of the incision required to harvest the seventh rib, the limited 3-cm incision that is used has healed favorably in almost all cases. The other major drawback for seventh-rib harvesting is the dissection required through the overlying rectus abdominis muscle, but little technical difficulty or postoperative morbidity is added with muscle dissection. The seventh rib is advocated as the ideal choice for augmentation rhinoplasty and potentially other recipient sites.     

Importance of coronoidotomy and masticatory muscle myotomy in surgical release of trismus caused by submucous fibrosis

Thirty patients with trismus resulting from betel nut chewing-induced oral submucous fibrosis were treated with either fibrotic tissue release only (group I) or fibrotic tissue release in combination with masticatory muscle myotomy and coronoidotomy (group II). The latter procedures were only performed in patients whose intraoperative interincisal distance remained less than 35 mm immediately after submucous fibrous tissue release. There were eight and 22 patients in groups I and II, respectively. In group I patients, the average intraoperative interincisal distance improved from 19.5 mm to 42 mm. In group II patients, the average intraoperative interincisal distance improved from 13.5 mm to 27 mm after fibrotic tissue release and further improved to 40 mm after masticatory muscle myotomy and coronoidotomy. At an average follow-up of 22.1 months (range, 7 to 70 months), the group I and II patients had an average interincisal distance of 41.5 mm (range, 35 to 50 mm) and 32.9 mm (range, 20 to 42 mm), respectively. These results demonstrate the efficacy of submucous fibrotic tissue release in treating trismus resulting from betel nut chewing-induced submucous fibrosis and confirm the role of additional masticatory muscle and coronoidotomy in treating its severe forms.