Masseteric Hypertrophy Research Articles

A masticatory mystery — the development of an intra-masseteric lump following botulinum toxin injection for masseteric hypertrophy

A masticatory mystery — the development of an intra-masseteric lump following botulinum toxin injection for masseteric hypertrophy

Repeated injections of botulinum toxin into the masseter muscle induce bony changes in human adults: A longitudinal study.

ObjectiveTo evaluate soft- and hard-tissue changes in the mandibular angle area after the administration of botulinum toxin type A (BoNT-A) injection to patients with masseteric hypertrophy by using three-dimensional cone-beam computed tomography (3D-CBCT).MethodsTwenty volunteers were randomly divided into two groups of 10 patients. Patients in group I received a single BoNT-A injection in both masseter muscles, while those in group II received two BoNT-A injections in each masseter muscle, with the second injection being administered 4 months after the first one. In both groups, 3D-CBCT was performed before the first injection and 6 months after the first injection.ResultsMasseter muscle thicknesses and cross-sectional areas were significantly reduced in both groups, but the reductions were significantly more substantial in group II than in group I. The intergonial width of the mandibular angle area did not change significantly in either group. However, the bone volume of the mandibular gonial angle area was more significantly reduced in group II than in group I.ConclusionsThe repeated administration of BoNT-A injections may induce bone volume changes in the mandibular angle area.

Masseter Treatment with Botulinum Toxin A for parafunctions and quadralized patients

INTRODUCTIONBotulinum toxin type A (BTxA) has gained worldwide popularity due to its ability to improve the lower facial contours and treat parafunctions.MATERIALS AND METHODSVarious analyses have been conducted through Medline searches for “Botulinum”, “masseter” and “bruxism” in order to investigate the different techniques used to inject the masseter muscle with Botulinum toxin. The authors’ experiences and techniques are fully explained regarding both functional pathologies and masseter size reduction. Personal guidelines to help physicians achieve the best outcomes for each application are outlined.Even if a definitive consensus on the use of Botulinum toxin for masseter muscle treatment cannot be reached, the authors recommend, due to their experience, three injection sites per side of the face for masseter hypertrophy and four injection sites per side for the redefinition of the inferior third of the face. Fewer units are needed to inhibit bruxism, while more units are needed in order to achieve a reduction in muscle size.RESULTSResults have been very good and patient satisfaction is usually very high. No side effects have been experienced as of the writing of this report.DISCUSSIONBTxA can be used as a therapeutic agent in bruxism patients and has been widely accepted as a cosmetic agent in recent years, helping to re-establish a balance in the contours of quadralized patients due to its positive clinical outcomes. Other clinical investigations are needed to improve the long-term effectiveness of Botulinum toxin.CONCLUSIONBotulinum toxin can be considered a safe and effective technique to treat related masseter parafunctions and to improve the shape of the lower face in quadralized patients.

Differences in Psychological Changes after Botulinum Toxin A Administration for Bruxism with Masseter Hypertrophy

This study aimed to assess changes in maximum bite force and psychological elements in patients with bruxism treated with botulinum toxin who visited the hospital with a chief complaint of masseter hypertrophy. From among the subjects with masseter hypertrophy as the chief complaint, 10 patients with and 10 without bruxism were selected. We measured bite force prior to botulinum toxin injection and at 2, 4, 8, and 12 weeks after the injection and assessed changes in psychological elements by using Symptom Checklist 90 Revision. The study results showed statistically significant differences in maximum bite force on both the right and left sides between the patients with and those without bruxism, according to periodic changes (p<0.05). Depression elements showed statistically significant changes in the patients with bruxism (p<0.05). In the bruxism and non-bruxism groups, the patients recovered from anxiety in accordance with the periodic changes (p<0.05). Our study results indicate that the patients with bruxism show significant changes in interpersonal sensitivity, depression, and anxiety according to the treatment periods, and that occlusal force and depression were significantly related. Therefore, when setting a treatment plan for bruxism, multilateral psychological elements must be considered, along with functional elements.

The efficacy of two formulations of botulinum toxin type A for masseter reduction: a split-face comparison study

Background: Botulinum toxin type A (BTA) is now extensively used to address cosmetic concerns. OnabotulinumtoxinA (ONA, Botox; Allergan Inc., Irvine, CA) received FDA approval for upper face rejuvenation, including glabella frown lines and crow’s-feet lines. The other off-label uses for lower face conditions have been utilized for contouring purposes, especially masseter hypertrophy. Recently, a new Daewoong BTA, (NABOTA®, NBT, Daewoong Pharmaceutical, Seoul, Korea), was recently introduced.Objective: To compare efficacy and safety of ONA and NBT for masseter reduction.Methods: Thirty-five subjects with masseter hypertrophy were randomly injected with 25 units of ONA on one side and 25 units of NBT on the other side into masseter. Standardized photographic documentation was obtained at baseline, 1, 3 and 6 months after treatment. The mean volume of masseter was acquired by using three-dimensional computed tomography (3-D CT) at baseline, 3-, and 6-month follow-up visits. In addition, patients’ satisfaction and side effects were also record at every follow-up visits.Results: The mean masseter volume on the sides treated with ONA and NBT at baseline were 21.20 ± 4.23 cm3 and 21.26 ± 4.58 cm3, respectively. There was no statistically significant difference in the mean volume of both sides (p= 0.827). The mean masseter volume at 3- and 6-month follow-up visits reduced significantly on both ONA and NBT sides (p< 0.001 and p< 0.001, respectively). However, there was no statistically significant difference in mean masseter volume when comparing between ONA and NBT sides at 3 and 6 months after treatment (p= 0.769 and p = 0.346, respectively). There was also no statistically significant difference in masseter reduction when compared between ONA and NBT sides evaluated by physicians and patients at each follow-up visit. No side effect on both sides was reported after injection.Conclusions: This study demonstrated that ONA and NBT provided comparable efficacy and safety for masseter reduction.

Botox – A New Weapon in a Dentist's Arsenal

AbstractBotulinum toxin was first used therapeutically by a German physician Justinus Kerner (1786-1862). Trade name BOTOX was given by Allergan, Inc, Irvine, Calif for treating strabismus, blepharospasm, and hemifacial spasm. It is neurotoxin derived from an anaerobic bacteria Clostridium botulinum. The toxin inhibits the release of acetylcholine (ACH), a neurotransmitter responsible for the activation of muscle contraction and its administration results in diminution of tone in the injected muscle. It has found a variety of uses in dentistry like treatment of gummy smile, masseteric hypertrophy, bruxism, temporomandibular disorders and so on. It is a minimally invasive and cosmetically effective method of treating several conditions with excessive muscle contraction.

Intramuscular Hemangioma Misdiagnosed as Unilateral Masseter Hypertrophy: A Case Report

Intramuscular hemangioma is a rare type of hemangiomas and sometimes overlooked by orofacial pain specialist who encountered various types of masticatory muscle problems. A 42-year-old male, presented with feeling of unilateral hypertrophy on left mandibular area, is finally diagnosed as hemangioma with thrombus by excisional biopsy. However, he was initially treated by injection of botulinum toxin A due to misdiagnosis as unilateral masseter hypertrophy. In the present report, we remind the importance of careful examination and diagnostic images to orofacial pain clinicians in early detection of intramuscular hemangioma of masticatory muscles.

Idiopathic bilateral masseter muscle hypertrophy in adolescent females of same family treated conservatively: a rare case report

Idiopathic hypertrophy of the masseter muscle is a rare disorder of unknown cause. Most patients complain of the cosmetic change caused by facial asymmetry, also called as Square face, however symptoms such as trismus, protrusion,bruxism may also occur. The goals of the present article are to- report 2 cases of idiopathic masseter hypertrophy within a same family, describe its symptoms and treatment. The main presenting complaints were bilateral bulging in the region of angle of mandible, of slow and progressive evolution and managed conservatively as oppose to the routine surgical treatment used so far.

咀嚼筋症状を伴う慢性GVHDの1例

Lichenoid changes, plate-like keratosis, and restriction of opening due to sclerotic lesion are typical lesions of oral GVHD. However, no case of opening failure due to masticatory muscle tone has been reported.We report a case of chronic GVHD presenting with masticatory muscle symptoms on admission. The patient, a 67-year-old man, developed dry eye after allogeneic bone marrow transplantation for myelodysplastic syndrome （MDS）/acute myeloid leukemia （AML） skin GVHD. The tooth, which was the source of infection, was extracted at a nearby hospital. After receiving prosthetic treatment, he started to experience muscle tension of the masticatory muscle and accidentally bit under the lip. The results of a head MRI scan did not reveal any central neurodegenerative diseases such as dystonia. A stabilization splint was set and a partial denture inserted, which resulted in improvement. Although masseter hypertrophy and trismus occurred, there was no deterioration even during the course of observation.

A Rare Association of Bilateral and Unilateral Masseter Hypertrophy with Hypertrophy of Pterygoids.

A Rare Association of Bilateral and Unilateral Masseter Hypertrophy with Hypertrophy of Pterygoids.

Comparison of clinical efficacy between radiofrequency ablation and botulinum toxin type A in treatment of benign masseter hypertrophy

Objective To evaluate masseter thickness and its complications of radiofrequency ablation and botulinum toxin type A in the treatment of masseter hypertrophy. Methods Totally 36 patients of benign masseter hypertrophy were randomly divided into radiofrequency ablation therapy group (18 patients) and the injection of botulinum toxin type A treatment group (18 patients). The thickness of the masseter and complications were analyzed before treatment, 6 months and 12 months after treatment. Results The average thickness of masseter muscle in botulinum toxin type A and radiofrequency ablation groups was significantly reduced 6 or 12 months after treatment, and the difference was statistically significant (P0.05). However, the thickness of masseter muscle in radiofrequency ablation group after 12 months reduced greater than that in botulinum toxin type A group (P0.05). Complications of botulinum toxin type A group were swallow difficulty (one patient), unnatural facial expressions (4 patients) and pain at injection site (10 patients) and that in radiofrequency ablation treatment group were that 18 patients had swelling of the skin 1 to 2 weeks after treatment. All patients had recovery 2 weeks after treatment. There was no facial nerve, parotid duct injury, or oral dysfunction. Conclusions The lasting effect of radiofrequency ablation treatment for benign masseter hypertrophy is longer than that of botulinum toxin type A. Key words: Benign masseter hypertrophy; botulinum toxin type A; radiofrequency ablation

Botulinum toxin in masticatory muscles of the adult rat induces bone loss at the condyle and alveolar regions of the mandible associated with a bone proliferation at a muscle enthesis

In man, botulinum toxin type A (BTX) is injected in masticatory muscles for several indications such as trismus, bruxism, or masseter hypertrophy. Bone changes in the mandible following BTX injections in adult animal have therefore became a subject of interest. The aim of this study was to analyze condylar and alveolar bone changes following BTX unilateral injections in masseter and temporal muscles in adult rats. Mature male rats (n=15) were randomized into 2 groups: control (CTRL; n=6) and BTX group (n=9). Rats of the BTX group received a single injection of BTX into right masseter and temporal muscles. Rats of the CTRL group were similarly injected with saline solution. Rats were sacrificed 4weeks after injections. Masticatory muscles examination and microcomputed tomography (microCT) were performed. A significant difference of weight was found between the 2 groups at weeks 2, 3 and 4 (p<0.05). Atrophy of the right masseter and temporal muscles was observed in all BTX rats. MicroCT analysis showed significant bone loss in the right alveolar and condylar areas in BTX rats. Decrease in bone volume reached −20% for right alveolar bone and −35% for right condylar bone. A hypertrophic bone metaplasia at the digastric muscle enthesis was found on every right hemimandible in the BTX group and none in the CTRL group. BTX injection in masticatory muscles leads to a significant and major mandible bone loss. These alterations can represent a risk factor for fractures in human. The occurrence of a hypertrophic bone metaplasia at the Mus Digastricus enthesis may constitute an etiological factor for tori.

Case Report of Meckel Cave Mass and Unilateral Masseter Hypertrophy Managed with Serial Botox Injections

We present a case report of a young girl who initially presented with asymmetric fullness of the left face and was found to have unilateral masseter hypertrophy at 9 years. An MRI was performed, revealing an ipsilateral mass within the Meckel cave, involving the trigeminal ganglion and tracking along V3 through the foramen ovale into the infratemporal fossa. At 14 years of age, an endoscopic biopsy was performed of V3 within the Meckel cave. The nerve was traced into the infratemporal fossa and was markedly enlarged. Multiple biopsies were taken of the neural tissue and surrounding fibrofatty tissues with no abnormalities found. By 15 years of age, she began to develop mild trismus and intermittent painful muscular spasms. She was initiated on serial Botox injections which have been continued since this time. Her spasm and facial asymmetry have improved substantially as has her trismus. The abnormal enlargement of the trigeminal nerve has been followed with repeated MRI and has demonstrated no further enlargement or changes.

Unilateral Benign Masseteric Hypertrophy: Surgical Intervention and Case Report

Hypertrophy is related to an enlargement caused by a growth in the size but not in the number of cells. Generalized masticatory muscle hypertrophy may affect the temporalis muscle, masseters, and medial pterygoids in a variety of combinations. Masseter hypertrophy is recognized as a rare disorder and persistent asymptomatic enlargement of one or both masseter muscles. Etiology for benign masseteric hypertrophy is unknown in most of the cases so considered as idiopathic. Although numerous factors such as facial asymmetry, trismus, protrusion, bruxism, clenching, malocclusion, or temporomandibular disorders have been reported on the basis of clinical examination and cited previous literatures but have not proven still. This article reports a case of unilateral benign masseter hypertrophy with retrognathic mandible in which surgical intervention was rendered to the patient by using a combination approach.

Management of Acquired Bilateral Masseteric Hypertrophy-A Case Report

ABSTRACT Masseter muscle hypertrophy is a rare condition of unknown cause, which is important due to growing cosmetic concern. A hypertrophied masseter may cause prominent mandibular angle, alter facial lines and characteristic square configuration of face, which may be unacceptable to the patient. Several treatment options reported for masseter hypertrophy, which range from conservative treatment options to invasive surgical procedure. The botulinum therapy offers good results but it's expensive and requires repeated injections with the chances of antibodies development. However, surgical treatment though invasive provides quick and permanent treatment for masseter muscle hypertrophy. The present case reports surgical management of young male patient with masseter hypertrophy due to cosmetic reasons.

Prolonging the duration of masseter muscle reduction by adjusting the masticatory movements after the treatment of masseter muscle hypertrophy with botulinum toxin type a injection.

Botulinum toxin type A (BTX-A) is widely used for the clinical treatment of masseteric hypertrophy. Until now, few reports have discussed how to prolong the duration of its effectiveness. This study evaluated that purposely adjusting the masticatory movements is possible of postponing the masseter muscle rehypertrophy. Ninety-eight patients were randomly and equally divided into 2 groups, and 35 U BTX-A per side was injected into the masseters. The thickness and volume of the masticatory muscles were measured by ultrasound and computerized tomography, respectively. Patients in Group 1 were instructed to strengthen their masticatory effort during the denervated atrophic stage of the masseter (the interval was evaluated by real-time ultrasound monitoring), whereas patients in Group 2 were not given this instruction. When the masseter muscle began to recover, patients in both groups were instructed to reduce their chewing. The duration of the masseter muscle rehypertrophy was significantly prolonged in Group 1 patients. The thickness and the volume of the other masticatory muscles were significantly increased in Group 1 but were either slightly decreased or insignificantly different in Group 2. Purposely strengthening masticatory muscle movement during the denervated atrophic stage of the masseter can prolong the duration of masseter rehypertrophy.

The risorius muscle: anatomic considerations with reference to botulinum neurotoxin injection for masseteric hypertrophy.

The botulinum neurotoxin Type A (BTX) injection into the masseter muscle often causes a change in the facial expression. There is as yet no precise anatomic evidence to support this etiologic factor of constrained facial expressions. The aim of this study was to clarify the location and boundaries of the risorius muscle and its topographical relationship with the surrounding structures. This study involved the dissection of 48 hemifaces. The locations of origin and insertion points of the risorius muscle were measured, and the masseter muscle was divided into 6 equally sized rectangular areas. Cases where the masseter muscle was covered by the risorius muscle were classified into the following 4 types: in Type A, Area III was partially covered by the risorius (17.8%); in Type B, Area VI was partially covered (20.0%); in Type C, Areas III and VI were partially covered (53.3%); and in Type D, Areas II, III, and VI were covered (6.7%). These findings suggest that the medial part of the masseter muscle represents a hazard zone into which the injection of BTX may affect the risorius muscle, potentially resulting in iatrogenic unnatural facial expressions.

The topographic anatomy of the masseteric nerve: A cadaveric study with an emphasis on the effective zone of botulinum toxin A injections in masseter

Botulinum toxin injections are previously reported to be a noninvasive alternative method for treating masseteric hypertrophy. However, there is a debate on finding an ideal place for injection. The aim of this study is to document the anatomical landmarks for defining the motor nerve entry points (MNEPs) of the masseteric nerve in the masseter for effective botulinum toxin injections. Twelve sides from six adult fixed cadavers were used for this study. The MNEPs of the masseteric nerve were defined according to standard landmark lines including the orbitomeatal line (OML) and the line (VL), which intersects the mid-distance of the OML to the tip of the angle of the mandible. All MNEPs were located 4.4 cm inferior to the OML. In addition, the average anterior distance of the MNEPs to the VL was 1.4 cm and the average posterior distance was 0.6 cm. The ideal site of Botox injection into the masseter is a rectangular area: 5 cm inferior to the OML, 1 cm anterior and posterior to the VL, and just above the periosteum. Based on the data of our study, injections to the parotid gland and branches of the facial nerve such as the marginal mandibular and buccal can be avoided. The masseteric nerve can easily be found approximately 1.0-1.5 cm inferior to the zygomatic arch, 1 cm medial to the temporomandibular joint capsule, and 1 cm superior to mandibular notch, which makes its use for facial reanimations more efficient.

Advanced Botulinum Toxin Injections for Dynamic Rhytides: Treating the Upper Face, Lower Face, and Beyond

Botulinum toxin (BT) is a neurotoxin produced by Clostridium botulinum, a Gram-positive anaerobic bacterium with different serotypes. It blocks acetylcholine release after binding to the presynaptic cholinergic receptors, thus preventing muscular contraction of the affected muscles. The muscular effects of BT usually last approximately from 3 to 6 months. Only botulinum neurotoxin A (BoNT-A) and botulinum neurotoxin B (BoNT-B) are commercially available and are approved for cosmetic and therapeutic uses. The BoNT-A is the most used serotype and the onabotulinumtoxin A (ONA), and abobotulinumtoxin A (ABO) are the prototypical products. The main cosmetic indications of BT are facial dynamic wrinkles, including the three thirds of the face, facial asymmetry, and masseteric hypertrophy as well as platysmal bands and selected chest wrinkles. BoNT-A injections can be safely combined with different cosmetic procedures. BT injections are considered a safe and efficient procedure, when performed by an experienced professional. Side effects are temporary and usually injection-related.

Midcheek mass: 10 year of clinical experience

This is a literature review and retrospective chart review of ten years experience on the treatment of midcheek masses in our department. The purpose of this study is to provide the reader with an overview of the pathology of this complex anatomic area focusing the attention on the differential diagnosis and the recent surgical strategies.From May 2002 to December 2012 we enrolled 22 consecutive patients studied for masses located in the midcheek area. Only four studies were found in the literature describing the experience of individual centres reporting few cases of midcheek masses. Combined with the previously reported 37 cases, we describe 22 lesions for a total of 59 cases. Patients were evaluated with a head and neck clinical and instrumental examination. Apart from 4 cases treated with intramuscular infiltration of botulinum toxin for masseter hypertrophy, surgical approach to the lesions was varied: 10 patients received an external approach (standard parotidectomy approach or face-lift-type approach); 6 patients had the lesion removed through an intraoral approach; in 2 cases a direct skin incision was performed. In our series we found a significant rate (55.5%) of temporary complications in all the procedures performed (external, intraoral, direct skin approach). This study aims to emphasize the role of endoscope assisted surgery as a possible alternative to the traditional approaches for the management of well selected benign midcheek masses.It would be advisable to increase the study of the endoscopic anatomy of the midcheek area in order to standardize the procedure and better define the surgical indications.