Medial Pterygoid Muscle Research Articles

Clinical evaluation of a newly developed method for avoiding artifacts caused by dental fillings on X-ray CT

To evaluate the clinical usefulness of gantry tilt scanning as an image reconstruction technique for avoiding artifacts caused by metallic dental fillings. Gantry tilt scanning was used with multidetector-row computed tomography for imaging in patients with dental fillings. Using a novel PC-based program, the oblique images obtained were reconstructed to transverse images using nearest neighbor and bilinear interpolation methodologies in order to avoid metallic streak artifacts. Coronal images were reformatted with the reconstructed transverse images, and the continuity of the reconstructed images was evaluated. Gantry tilt scanning was performed in 12 patients with metal artifacts, and the original and reconstructed images were classified into four grades and assessed by two radiologists. Results of the clinical evaluation indicated that the original images with artifacts, only 4% had good image quality in the region around the medial pterygoid muscle, only 8% depicted areas around the internal carotid artery and internal jugular vein, and only 12% could depict the areas around the parotid gland in the clinical evaluation. These values were improved to 60, 96, and 100%, respectively, in the reconstructed transverse images. Gantry tilt scanning as an image reconstruction technique improves image quality and removes most, if not all, artifacts caused by metallic dental fillings. The resulting images can be used in the evaluation of oropharyngeal lesions in patients with dental fillings.

Three-Dimensional CT Examination of the Mastication System in the Giant Anteater

The gross anatomy of the mastication system of the giant anteater (Myrmecophaga tridactyla) was examined by means of three-dimensional image analysis. The anteater rotates the mandibles medially and laterally to control its tongue when it is elongated and to house it when it is relaxed. Three-dimensional CT image analysis demonstrated that the shape and size of the oral cavity changes drastically when the mandibles are rotated. The oral cavity expands bilaterally when the dorsal part of the mandibles bend medially. Macroscopic observations and muscle-weight data supported the observation that the superficial temporal and medial pterygoid muscles act as the main medial and lateral rotators of the mandible, respectively. The low height of the mandibular ramus and the incomplete zygomatic arch in this species represent adaptations for the rotational movement of the mandibles, since they both contribute to the medially oriented transmission of force from the temporal muscles and to preventing collision between the mandibles and the cranium during the rotational movement.

Microanatomy and Surgical Approaches to the Infratemporal Fossa: An Anaglyphic Three-Dimensional Stereoscopic Printing Study

The infratemporal fossa (ITF) is a continuation of the temporal fossa between the internal surface of the zygoma and the external surface of the temporal bone and greater wing of the sphenoid bone that is sitting deep to the ramus of the mandible. The principal structure to understanding its relationships is the lateral pterygoid muscle. Other important structures are the medial pterygoid muscle, the maxillary artery, the pterygoid venous plexus, the otic ganglion, the chorda tympani nerve and the mandibular nerve. In this study, we describe the microsurgical anatomy of the ITF, as viewed by step-by-step anatomical dissection and also through the perspective of three lateral approaches and one anterior surgical approach. Eight cadaver specimens were dissected. In one side of all specimens, an anatomical dissection was done in which a wide preauricular incision from the neck on the anterior border of the sternoclidomastoid muscle at the level of the cricoid cartilage to the superior temporal line was made. The flap was displaced anteriorly and the structures of the neck were dissected followed by a zygomatic osteotomy and dissection of the ITF structures. On the other side were the surgical approaches to the ITF. The combined infratemporal and posterior fossa approach was done in two specimens, the subtemporal preauricular infratemporal fossa approach in two, the zygomatic approach in two, and the lateral transantral maxillotomy in two. The anatomical dissections were documented on the three-dimensional (3D) anaglyphic method to produce stereoscopic prints. The lateral pterygoid muscle is one of the principal structures to enable understanding of the relationships into the ITF. The tendon of the temporal muscle inserts in the coronoid process at the ITF. The maxillary artery is the terminal branch of the external carotid artery that originates at the neck of the mandible and runs into the parotid gland. In our dissections the maxillary artery was lateral to the buccal, lingual, and inferior alveolar nerves. We found the second part of the maxillary artery superficial to the lateral pterygoid muscle in all specimens The anterior and posterior branches of the deep temporal artery supply the temporal muscle. In two cases we found a middle deep temporal artery. The different approaches that we used provided different views of the same anatomical landmarks and this provides not only safer surgery but also the best choice to approach the ITF according with the pathology extension. The ITF is a complex region on the skull base that is affected by benign and malignant tumors. The study through different routes is helpful to disclose the relationship among the anatomical structures. Although the authors have shown four approaches, there are a variety of approaches and even a combination of these can be used. This type of anatomical knowledge is essential to choosing the best approach to treat lesions in this area.

Ultrastructural and biochemical changes of the medial pterygoid muscle induced by unilateral exodontia

The aim of the present study was to investigate the histological, biochemical and ultrastructural effects of occlusal alteration induced by unilateral exodontia on medial pterygoid muscle in guinea pigs, Cavia porcellus. Thirty ( n = 30) male guinea pigs (450 g) were divided into two groups: experimental-animals submitted to exodontia of the left upper molars, and sham-operated were used as control. The duration of the experimental period was 60 days. Medial pterygoid muscles from ipsilateral and contralateral side were analyzed by histological ( n = 10), histochemical ( n = 10), and ultrastructural ( n = 10) methods. The data were submitted to statistical analysis. When the ipsilateral side was compared to the control group, it showed a significantly shorter neuromuscular spindle length ( P < 0.05), lower oxidative metabolic activity, and microvessel constriction, in spite of the capillary volume and surface density were not significantly different ( P > 0.05). In the contralateral side, the neuromuscular spindles showed significantly shorter length ( P < 0.05), the fibers reflected a higher oxidative capacity, the blood capillaries showed endothelial cell emitting slender sprouting along the pre-existing capillary, and significantly higher blood capillary surface density, and volume density ( V v = 89% Mann–Whitney test, P < 0.05). This finding indicated a complex morphological and functional medial pterygoid muscle adaptation to occlusal alteration in this experimental model. Considering that neuromuscular spindles are responsible for the control of mandibular positioning and movements, the professional should consider if these changes interfere in the success of clinical procedures in medical field involving stomatognathic structures.

Relationship Between the Masticatory Muscles and Mandibular Skeleton in Mandibular Prognathism With and Without Asymmetry

The purpose of the present study was to evaluate the relationship between masticatory muscle volume and mandibular skeletal measurements in patients with and without facial asymmetry. This was done in order to determine whether asymmetric mandibular prognathism is related to masticatory muscle asymmetry. The study was conducted with 40 adult patients with mandibular prognathism composed of 2 groups, the asymmetry group (n = 20) and the nonasymmetry group (n = 20). Using 3-dimensional reformatted computed tomography (CT) images, the volume of masticatory muscle (masseter, temporal, medial, and lateral pterygoid muscles) and various skeletal measurements (hemimandibular volume, ramal height, body length, mandibular length, gonial angle) were evaluated and compared. The right-left difference was expressed by an asymmetry index {(right-left)/left, %}. The results showed that in the asymmetry group, the longer mandibular side (contralateral side of chin deviation) exhibited longer ramal and body length, a wider gonial angle, and more hemimandibular volume with less medial pterygoid volume, whereas the nonasymmetry group did not show a statistical bilateral difference between the skeletal and muscular measurements. The correlation analysis showed that patients with facial asymmetry did not have similar patterns of muscle-bone relation as compared with the symmetrical subjects. In patients with mandibular prognathism, the bilateral difference in muscle volume would reflect the difference in the spatial anatomy of a skeletal structure and could not predict mandibular skeletal asymmetry.

Macroscopic Anatomy of the Sphenomandibular Ligament Related to the Inferior Alveolar Nerve Block

We performed macroscopic observations of the sphenomandibular ligaments, and measured the space that is surrounded by the mandibular ramus and the ligament by using computed tomography. The materials used in this study were 40 heads of 40 adult cadavers. The cadaver head was cut on the mid sagittal plane. The medial pterygoid muscles of the cadavers were removed to observe the ligaments. The attaching style of the sphenomandibular ligament to the mandibular ramus was classified into three types: Type I (5 in 40 samples; attached only to the mandibular lingula), Type II (12 in 40 samples; attached to the mandibular lingula and extended toward the rear part of the internal surface of the mandibular ramus), and Type III (23 in 40 samples; attached to the mandibular lingula and toward the posterior border of the mandibular ramus). There was no statistical difference in the length of the ligament among the three types. However, Type III showed the largest width, and the space was approximately eight and three times as large as those of Type I and II, respectively. This indicated that the Type III ligament covered a larger area over the mandibular foramen than Type I. These results suggest that the three-dimensional morphology of the sphenomandibular ligament, as represented by Type III, may affect the effectiveness of anesthesia.

Biomechanical Evaluation of Le Fort I Maxillary Fracture Plating Techniques

This study used a biomechanical model to examine fundamental questions about rigid plate fixation treatment for maxillary Le Fort I fractures. Specifically, we sought to elucidate the principal strain patterns generated in miniplates and bite force transducers secondary to all masticatory forces, as well as the amount of permanent deformations incurred due to these loading forces. Forty polyurethane synthetic maxillary and mandibular replicas were used to simulate the mandible and maxilla. Ten replicas were controls (group A). The other 30 were divided into 3 groups (10 each), according to the fixation techniques of 3, 2, and 1 miniplates each side (groups B-D), that were osteotomized in the Le Fort I fracture line on the maxilla. Different forces of masseter medial pterygoid, temporalis, and lateral pterygoid muscles were loaded onto the replicas to simulate different functional conditions (anterior incisor, premolar, and molar clenching). Rosette strain gauges were attached at predefined points on the plates and the bite force transducer to compare the stability and bite force of the different fixation methods for maxillary Le Fort I fractures. Statistically significant differences were found for the deformation of the plates among fixation techniques. The order of stability for each technique was: group B greater than group C greater than group D. In regard to bite force, no difference was found between those found with group A and group B (P > .05), whereas the bite forces of groups C and D were less than those of group A (P < .05). The fixation of 3 miniplates on each side provides sufficient stability and restores the bite force to the level of the intact maxilla. "The ideal fixation" with 2 miniplates on each side restores 90% of the bite force, and there were more deformations of the miniplates with the "ideal fixation" compared to those found with group B. Group D fixation produced the worst effects for the treatment of maxillary Le Fort I fractures with a weak bite force and insufficient stability.

Botulinum Toxin in Closed Treatment of Mandibular Condylar Fracture

The topic of condylar injury in adults has generated more discussion and controversy than any other in the field of maxillofacial trauma. The treatment of condylar fractures in adults is still a highly debated theme. Patients with unilateral subcondylar or condylar neck fractures of the mandibula without any significant angulation of the condylar head were managed with closed-treatment protocol. Closed treatment was applied through the injection of 100 units of botulinum toxin A, diluted to a concentration of 20 IU/mL, into the muscles of mastication of the fractured side. Masseter and anterior fibers of temporalis muscles were reached through percutaneous extraoral route and 30 IU of the toxin was injected to each muscle. Additional 40 IU of the toxin was injected around the fractured bone fragments through transmucosal intraoral route to paralyze medial and lateral pterygoid muscles as much as possible. An asymmetric occlusal splint was applied for maxillomandibular fixation to restore the vertical height for 10 days. Functional therapy with intermaxillary guiding elastics was advocated for 2 months. There were no complications related to either toxin injections or splint application procedures. The toxin was effective on all occasions. Fractured condylar process and ramus of the mandibula were in good approximation and remained in reduced positions. None of the patients had any occlusal disturbance, mandibular asymmetry, or joint dysfunction in the follow-up period. We believe that modification of treatment options concerning the clinical situation of the patients is the best method for condylar injury. The purpose of this study is to present and discuss the results achieved in closed treatment of a selected group of patients with mandibular condylar fractures to whom botulinum toxin A was injected to relieve the spasm of muscles of mastication, along with special splint application.

Masticatory motor patterns in ungulates: a quantitative assessment of jaw‐muscle coordination in goats, alpacas and horses

We investigated patterns of jaw-muscle coordination during rhythmic mastication in three species of ungulates displaying the marked transverse jaw movements typical of many large mammalian herbivores. In order to quantify consistent motor patterns during chewing, electromyograms were recorded from the superficial masseter, deep masseter, posterior temporalis and medial pterygoid muscles of goats, alpacas and horses. Timing differences between muscle pairs were evaluated in the context of an evolutionary model of jaw-muscle function. In this model, the closing and food reduction phases of mastication are primarily controlled by two distinct muscle groups, triplet I (balancing-side superficial masseter and medial pterygoid and working-side posterior temporalis) and triplet II (working-side superficial masseter and medial pterygoid and balancing-side posterior temporalis), and the asynchronous activity of the working- and balancing-side deep masseters. The three species differ in the extent to which the jaw muscles are coordinated as triplet I and triplet II. Alpacas, and to a lesser extent, goats, exhibit the triplet pattern whereas horses do not. In contrast, all three species show marked asynchrony of the working-side and balancing-side deep masseters, with jaw closing initiated by the working-side muscle and the balancing-side muscle firing much later during closing. However, goats differ from alpacas and horses in the timing of the balancing-side deep masseter relative to the triplet II muscles. This study highlights interspecific differences in the coordination of jaw muscles to influence transverse jaw movements and the production of bite force in herbivorous ungulates.

Masticatory muscles of the great‐gray kangaroo (Macropus giganteus)

The great-gray kangaroo (Macropus giganteus) belongs to the Diprotodontia suborder (herbivorous marsupials of Australia) of the order of marsupials. We dissected the masticatory muscles in the great-gray kangaroo and classified them based on their innervation. Three (two male and one female) adult great-gray kangaroos (M. giganteus), fixed with 10% formalin, were examined. The masseter muscle of the great-gray kangaroo was classified into four layers (superficial layers 1, 2, 3, and a deep layer), all innervated by masseteric nerves. Layer 1 of the masseter muscle was well developed and the deep layer inserted into the masseteric canal. The zygomaticomandibular muscle, which belongs to both the masseter and temporalis muscles, was innervated by both the masseteric nerve and posterior deep temporal nerve, and the temporalis muscle was innervated by the anterior and posterior deep temporal nerves. The medial pterygoid muscle, which was innervated by the medial pterygoid nerve, was divided into superficial and deep portions. The lateral pterygoid muscle was divided into superior and inferior heads by the buccal nerve. We propose that the relationship of the masticatory muscles in the kangaroo has evolved by passive anterior invasion of the deep layer of the masseter by the medial pterygoid muscle via the masseteric canal, associated with the development of an anteroposterior mode of mastication.

Anatomical study of the arrangement and attachments of the human medial pterygoid muscle

The authors have studied the medial pterygoid muscle on 179 fresh cadavers using anatomical dissection and magnetic resonance imaging (MRI). The aim of this study was to define the general morphology and architectural organisation of the human medial pterygoid. Plane by plane dissection, anatomical sections in different spatial planes on half heads and isolated blocks demonstrated that the medial pterygoid has different architectural disposition and insertional zones from those which are normally described. The study has shown that the muscle has a typical penniform structure made up of seven alternating muscular/aponeurotic layers and that the tendinous intramuscular sheets were particularly well developed. This allows supporting a future functional study.

The clinical anatomy of complications observed in a posterior superior alveolar nerve block

The use of anesthetics in dentistry is necessary to prevent pain in precise areas of the oral cavity. This is accomplished by blocking branches of the trigeminal nerve. For treatment of the maxillary molars (with the possible exception of the mesiobuccal root of the 1st maxillary molar) and the buccal soft tissues, a posterior superior alveolar (PSA) nerve block is employed. This injection targets the PSA nerve in the infratemporal fossa. To properly perform the injection, deposition of the anesthetic needs to be placed along the posterior surface of the maxilla. The needle must be advanced approximately 15mm in the following x-y-z plane at the same time to reach the PSA nerve along the posterior surface of the maxilla: medially, superiorly, and posteriorly at a 45 degree angle to the maxillary occlusal plane. Various complications can result from an improperly placed PSA nerve block. The most common complication is a hematoma resulting from trauma to the pterygoid plexus of veins. Another reported complication, although uncommon, is a temporary Bell’s Palsy if the needle is improperly placed into the parotid bed. Although a short needle is recommended for a PSA injection, many clinicians utilize long needles. In this study, an experienced dentist placed a 25 gauge long needle in the oral cavity of fresh tissue cadavers. A 1.8 ml carpule of 10% methylene blue was then injected into the site. To examine the extravasation of the dye in the tissue, dissections were performed and digital images were taken. We observed that using proper technique, the anesthetic would label the PSA nerve. However, improper placement of the needle could lead to damage of the pterygoid plexus, labeling of the inferior portion of the parotid gland with the cervicofacial division of the facial nerve, and labeling in the lateral or medial pterygoid muscles which would result in trismus.

Involvement of pterygoid venous plexus in patulous eustachian tube symptoms

Conclusions. The pterygoid venous plexus (PVP) is an important factor in the mechanism of eustachian tube (ET) closure under conditions that can cause increased venous pressure in the head, such as during neck compression and postural change from the sitting/standing to the recumbent position. Objectives. The symptoms of patulous ET are usually improved by neck compression or postural change (from sitting/standing to recumbent position). Venous congestion around the ET and/or gravitational change may be involved in the changing degree of symptoms, but its mechanism is not understood. This study investigated whether the PVP is involved. Materials and methods. The dimensions of soft tissues surrounding ET were measured on magnetic resonance images before and after neck compression. Results. The lateral pterygoid muscle became enlarged after neck compression. Simultaneously, the volume of venous plexus observed between the medial pterygoid muscle and tensor veli palatini muscle was increased. Such enlargement was probably due to blood pooling in the PVP, resulting in protrusion of the ET anterior wall to the luminal side, and decreased ET patency.

Effects of Low-level Laser in the Treatment of Myofascial Pain Dysfunction Syndrome.

Background and aims Muscular pain in the facial region is the most common cause of facial pains. Myofascial pain dysfunction syndrome (MPDS) is one of the most important facial muscle disorders comprising of signs and symptoms including pain during function, tenderness in the muscles of mastication and restricted jaw movement. Due to the lack of an accepted therapeutic approach, the purpose of this paper was to find an effective treatment to decrease the pain of such patients. Considering the analgesic and anti-inflammatory action of laser therapy, the effects of low level laser (Ga-Al-As) in the treatment of MPDS patients referred to Tehran University of Medical Sciences Faculty of Dentistry, were investigated in the present study. Materials and methods This study was a quasi-experimental research. Twenty-two MPDS patients were selected from those referred to Department of Oral Medicine, Tehran University of Medical Sciences Faculty of Dentistry. Clinical examination was performed at six stages in the following order: prior to the treatment, at 2 and 4 weeks after treatment, and monthly thereafter for a 3-months follow-up. All patients underwent low-level laser therapy for 4 weeks (12 sessions). Variables such as pain severity, pain of cheek region, pain frequency, tenderness of masticatory muscles, click, and mouth opening were evaluated at each stage. Numerical variables were investigated using Analysis of Variance test for repeated measures whereas ranking variables were studied by non-parametric Kruskal-Wallis test. Results At the end of treatment period, pain severity, pain of cheek region, pain frequency, tenderness of masseter, temporalis, medial pterygoid, and lateral pterygoid muscles showed significant improvement as compared with the commencement of any treatment which continued during the 3-months post-treatment (p<0.05). Conclusion It was shown that low-level laser (Ga-Al-As) therapy had the efficacy to alleviate pain and decrease the tenderness of masticatory muscles among MPDS patients through a continuous and regular therapeutic program.

Topography and Morphology of the Medial Pterygoid Muscle for the Surgical Approach of the Mandibular Ramus

Topography and Morphology of the Medial Pterygoid Muscle for the Surgical Approach of the Mandibular Ramus

Effectiveness of dexamethasone and low-power laser in minimizing oedema after third molar surgery: a clinical trial

Postoperative oedema is common following removal of impacted lower third molars. Several types of drug therapy (corticosteroids, non-steroidal anti-inflammatory drugs, enzymes) have been tried. The aim of this study was to compare the effectiveness of low-power laser (LPL) and dexamethasone after surgical removal of impacted lower third molars under local anaesthesia (2% lidocaine/epinephrine). Material and methods There were 120 healthy patients divided into four groups of 30 each. Group 1 received LPL irradiation immediately after operation (energy output 4 J/cm 2 with constant power density of 50 mW, wavelength 637 nm); group 2 also received i.m. injection of 4 mg dexamethasone (Dexason ®) into the internal pterygoid muscle; group 3 received LPL irradiation supplemented by systemic dexamethasone (Dexason ®), 4 mg i.m. in the deltoid region, followed by 4 mg of dexamethasone intraorally 6 h postoperatively; and the fourth (control) group received only the usual postoperative recommendations (cold packs, soft diet, etc.). Results LPL irradiation with local use of dexamethasone (group 2) resulted in a statistically significant reduction of postoperative oedema in comparison to the other groups. No adverse effects of the procedure or medication were observed. Conclusion LPL irradiation after lower third molar surgery can be recommended to minimize swelling. The effect is enhanced by simultaneous local intramuscular use of dexamethasone.

Adaptation of jaw closing muscles after surgical mandibular advancement procedures in different vertical craniofacial types: a magnetic resonance imaging study

Surgical mandibular advancement influences the biomechanics of the mandible and as a result may provoke relapse. In this study, the adaptation of the masseter (MAS) and medial pterygoid muscles (MPM) after surgical mandibular advancement was evaluated. Of 12 patients with mandibular retrognathia and varying vertical craniofacial morphology, axial and 30 degrees angulated magnetic resonance imaging (MRI) scan series were taken preoperatively and 10 to 48 months postoperatively. Using cluster analysis, subjects were assigned to a long-face (LF) and a short-face (SF) cluster. Subsequently, preoperative and postoperative maximum cross-sectional areas and volumes of the MAS and MPM were compared in these groups. The cross-sectional area and volume of the MAS decreased significantly in both the SF and LF cluster (up to 18%). Although not significantly, this phenomenon tended to be more pronounced in LF patients. The cross-sectional area of the MPM showed less adaptation. The jaw-closing muscles become significantly smaller after surgical mandibular advancement, irrespective of the vertical craniofacial type.

Magnetic resonance imaging of retropharyngeal lymph node metastasis in nasopharyngeal carcinoma: Patterns of spread

To investigate the incidence, distribution, and spread pattern of retropharyngeal lymph node (RLN) involvement in patients with nasopharyngeal carcinoma (NPC) by using magnetic resonance imaging (MRI). The MR images of 275 patients with newly diagnosed NPC were reviewed retrospectively. Nodes were classified as metastatic based on size criteria, the presence of nodal necrosis, and extracapsular spread. Retropharyngeal lymph node involvement was detected in 175 (63.6%) patients. Metastatic RLNs were seen at the following levels: occipital bone, 24 (9.6%) nodes; C1, 157 (62.5%) nodes; C1/2, 40 (15.9%) nodes; C2, 27 (10.8%) nodes; C2/3, 1 (0.4%) node; and C3, 2 (0.8%) nodes. The incidence of RLN involvement was equal to the incidence of cervical lymph node involvement (81.4% vs. 81.4%) in 215 patients with nodal metastases. A significantly higher incidence of metastatic RLNs was observed in the presence of oropharynx, prestyloid parapharyngeal space, post-styloid parapharyngeal space, longus colli muscle, medial pterygoid muscle, levator muscle of velum palatini, tensor muscle of velum palatini, Level II node, Level III node, and Level V node involvement. A significantly lower incidence of metastatic RLNs was found in T1, N0, and Stage I disease. Conversely, no significant difference in the incidence of metastatic RLNs was observed between T1, 2, and, 3; N2 and N3; or Stage II, III, and IV disease. There is an orderly decrease in the incidence of metastatic lateral RLNs from the C1 to C3 level. Metastatic RLNs associate well with involvement of certain structures in early stage primary tumors and lymph node metastases of the upper jugular chain (Level II, Level III nodes) and the posterior triangle (Level V nodes). Both RLNs and cervical Level II nodes appear to be the first-echelon nodes in NPC.

The volume of muscles of mastication in patients receiving mandibular contouring surgery: a comparative study

As the management of prominent mandibular angle and masseter muscle hypertrophy becomes increasingly popular, proper understanding of the volumetric component of the related structures becomes important but is currently lacking. Three-dimensional computed tomographic (CT) scans of 18 female and eight male adult patients with square-face appearance were used for volumetric measurement of the osseous hemi-mandible, masseter, medial and lateral pterygoid muscles. CT scans of 28 female and 17 male adult patients without square-face appearance were selected from the imaging laboratory archive to serve as controls. Compared with the sex-matched controls, the square-faced patients had significantly higher volume of the osseous hemi-mandible as well as the masseter and medial pterygoid muscles. There was no significant difference in the volume of the lateral pterygoid muscle between the two groups. This study confirms a significantly greater volume in the osseous mandible and masseter muscle in patients complaining of square-face appearance. The implication of this information on treatment is discussed.

P.216 Angiosarcoma of the lower lip in a young adult. A case report

Through our experiences in the parapharyngeal space (PPS) surgery, we have learned that it is possible to gain wide exposure of the PPS near to the skull base with a transcervical approach alone. Thus, we presumed that if this type of transcervical approach would be combined with a transoral approach, a less invasive oropharyngectomy without mandibulotomy and lip-splitting might be feasible for the resection of advanced oropharyngeal cancer, sparing the morbidities associated with conventional mandibular swing approach or its modified procedures. We termed this method as a mandible preserving pull-through oropharyngectomy (MPPO) and evaluated its feasibility and efficacy in this pilot study.MPPO was applied for a series of 7 patients with advanced lateral and/or upper oropharyngeal cancer including 2 patients with T4 stage. Our current application of MPPO excludes tumors, which involves mandibular bone, the higher part of the medial pterygoid muscle, and the lateral pterygoid muscle.Safe and sufficient excision of tumors was feasible by MPPO avoiding morbidities associated with mandibulotomy or lip-splitting without compromising oncological outcomes.Although preliminary, our favorable outcomes indicate that MPPO might be a useful alternative to conventional mandibular swing approach or its modified procedures for selected cases with advanced oropharyngeal cancer. Further accumulation of data is encouraged.