The masseter muscle is the primary muscle among the masticatory muscle group located in the mandibular angle area on both sides of the face — it originates from the lower border and medial surface of the zygomatic arch and inserts on the mandibular angle and lateral ramus. The masseter functions in jaw closure and chewing — when we clench our teeth, the bulging muscle masses at the mandibular angles are clearly palpable. Masseter hypertrophy is a common facial concern among East Asian populations, particularly East Asian women — enlarged masseters make the mandibular angle area noticeably wide, creating a square or trapezoidal face shape rather than the ideal oval or V-line. Causes of masseter hypertrophy include: (1) Genetics — some people naturally have larger masseter volume and thicker muscle fibers. (2) Chewing habits — long-term preference for hard foods (nuts, jerky, dried squid), frequent gum or betel nut chewing overdevelops the masseter. (3) Bruxism — unconscious teeth clenching during sleep causes sustained high-intensity masseter contraction, leading to compensatory hypertrophy over time. (4) Stress-related clenching — unconscious jaw clenching during mental tension. (5) Unilateral chewing — long-term preferential chewing on one side makes that masseter more developed, causing facial asymmetry. Rappoel Dermatology near Gangnam Station, Seoul, uses Korea’s Coretox botulinum toxin — precisely injecting the masseter for selective muscle atrophy and reduction, providing a safe, effective, non-surgical facial slimming solution.
Technical Principles of Coretox Masseter Reduction
- Botulinum toxin selective muscle atrophy mechanism: Coretox is botulinum toxin type A — when injected into the masseter, it blocks acetylcholine release at the neuromuscular junction, causing masseter muscle fibers to lose neural stimulation and enter a state of disuse atrophy. Muscle fibers gradually thin and volume decreases — clinical data shows masseter volume reduces by an average of 20-30% at 4-6 weeks post-injection, reaching maximum atrophy of approximately 30-40% at 3 months
- Coretox Korean-origin purity advantage: Coretox is a 150kDa high-purity toxin developed by Daewoong Pharmaceutical — unnecessary complex proteins removed, theoretically reducing antibody formation and resistance risk. For patients requiring long-term repeated injections (masseter reduction typically needs 2-3 sessions per year for maintenance), the high-purity formulation is more beneficial for maintaining consistent long-term results
- Faster onset (3-5 days): Coretox clinical data shows average onset of 2-3 days — masseter area effects begin appearing at 7-10 days (muscle starts relaxing), preliminary slimming visible at 2 weeks, optimal results at 4-6 weeks
- Precise diffusion control: The most critical safety consideration in masseter injection is preventing toxin spread to surrounding muscles — particularly the deep lateral pterygoid (spread may affect mouth opening) and superficial risorius (spread may affect smiling). Coretox’s smaller diffusion range makes it safer for masseter injection
- Preservative-free hypoallergenic formulation: Coretox contains no animal-derived proteins or human serum albumin — reducing allergic reaction risk, suitable for sensitive patients requiring long-term repeated injections
Detailed Anatomy and Safety for Masseter Injection
- Masseter three-layer anatomy: The masseter has superficial, middle, and deep layers — the superficial layer is largest and thickest (the primary injection target), while middle and deep layers are smaller. Injection targets mainly the superficial and middle layers — deep injection is high-risk (near the lateral pterygoid and facial nerve branches)
- Safe injection zone marking: Rappoel physicians have patients clench to mark the masseter bulge — injection points are strictly within: upper boundary below the tragus-to-mouth-corner line, lower boundary 1.5cm above the mandibular inferior border, anterior boundary at the masseter anterior edge, posterior boundary pre-auricular. 3-5 injection points per side distributed evenly
- Avoiding parotid duct and facial nerve: The parotid duct crosses the masseter surface (approximately 1cm below the zygomatic arch, parallel to it) with facial nerve buccal branches — injection needles angle downward into the muscle, avoiding the superficial parotid duct and nerve
- Precise dose distribution: Total Coretox per side: 25-40 units (adjusted for masseter volume) — divided across 3-5 points, 5-15 units each. Too low yields insufficient effect; too high may cause chewing weakness
- Avoiding asymmetry: Most people have asymmetric masseter size (related to unilateral chewing habits) — physicians measure bilateral masseter thickness before injection, adjusting dosage distribution based on asymmetry
Rappoel Masseter Botox Injection Treatment Protocol
- Facial assessment and plan design (10 min): Frontal and side evaluation of mandibular angle width → patient clenches to assess masseter bulge and thickness → evaluate facial symmetry → confirm no special conditions like bruxism → establish injection plan (points, dosage, bilateral distribution)
- Disinfection preparation (5 min): Facial cleansing → povidone-iodine bilateral mandibular angle preparation → mark injection points
- Precise injection (8-10 min): 30G ultra-fine needle → 3-5 injection points per side → injection depth within the masseter muscle belly (approximately 1-1.5cm deep) → 5-15 units Coretox per point → immediate gentle pressure for hemostasis
- Immediate assessment and guidance (5 min): Patient performs clenching and mouth opening to confirm normal function → post-care instructions (avoid pressing injection area, avoid lying flat for 4 hours, etc.) → 2-week follow-up scheduled for effect evaluation
The entire masseter Coretox injection takes about 20-25 minutes, with onset at 7-10 days, preliminary slimming at 2 weeks, optimal results at 4-6 weeks, lasting 4-6 months. Located 3 minutes from Gangnam Station Exit 10, with seamless English and Chinese consultation.
Frequently Asked Questions
How much smaller will my face get with masseter Botox? Is the effect noticeable?
The slimming effect depends on masseter hypertrophy degree and injection dosage: (1) Mild hypertrophy — facial width reduces by approximately 3-5mm at 1 month, subtle shift from square toward oval. (2) Moderate hypertrophy — 5-8mm reduction, noticeable decrease in mandibular angle width, significant frontal change. (3) Severe hypertrophy — 8-12mm reduction, dramatic change from obviously square to near-oval. Note: masseter Botox reduces muscle volume, not bone — if your square face also has wide mandibular bone (skeletal square face), Botox only reduces the muscle component; skeletal reduction requires orthognathic surgery or mandibular angle ostectomy. Rappoel physicians distinguish between muscular and skeletal square faces during assessment — muscular type responds dramatically to Botox; skeletal type may need combined surgical approach.
How long does masseter Botox last? Will it stop working over time?
Masseter Botox typically lasts 4-6 months — because the neuromuscular junction gradually regenerates acetylcholine receptors restoring muscle contraction, and muscle volume recovers accordingly. However, an important phenomenon: after each injection, the masseter cannot perform high-intensity chewing during the atrophy period — equivalent to passive exercise reduction. Many patients find that after 3-5 regular sessions, the masseter’s baseline volume is smaller than initially — even when Botox effect fades, the face doesn’t completely return to the original square shape. Regarding resistance: long-term repeated Botox injections may produce neutralizing antibodies causing diminished effect — incidence approximately 1-5%. Coretox’s high-purity formulation theoretically reduces antibody risk. Rappoel recommends: minimum 3-month intervals between injections, lowest effective dose, scientifically managed frequency to minimize resistance risk.
Will masseter Botox cause chewing weakness? Does it affect eating?
Mild chewing strength decrease may occur post-injection — particularly at 2-4 weeks when the effect is strongest, biting hard objects may feel effortful. But this is temporary and controllable: (1) Rappoel uses moderate dosage (25-40 units per side) — not completely freezing masseter function, only reducing 20-30% of contraction force. Normal eating is completely unaffected. (2) Chewing is primarily driven by the deep masseter and medial pterygoid — Rappoel’s injection targets mainly the superficial and middle layers, preserving deep function. (3) If significant chewing weakness occurs (usually from excessive dosage), the dose is reduced at the next session. Precautions: avoid particularly hard foods (nuts, hard candy) for 1 week post-injection, letting the masseter atrophy proceed without extra stimulation. The vast majority of patients eat normally without impact — only finding very hard items slightly more effortful than before.
What is the difference between Coretox and Botox for masseter reduction?
Coretox and Botox are both botulinum toxin type A with the same core mechanism, with these main differences: (1) Purity — Coretox is 150kDa high-purity toxin with complex proteins removed; Botox is 900kDa complex. (2) Onset speed — Coretox averages 2-3 days; Botox typically 5-7 days. For masseter reduction, Coretox may show muscle slimming at 5-7 days, while Botox takes 10-14 days. (3) Diffusion range — Coretox has smaller diffusion, safer for masseter injection (reduced risk of spreading to lateral pterygoid affecting mouth opening). (4) Formulation — Coretox contains no animal-derived proteins or albumin, lower allergy risk. (5) Supply — Coretox is domestically produced in Korea with stable supply. Both last similarly (4-6 months) with similar slimming effects. Rappoel selects based on patient needs — Coretox recommended for those wanting fast results or experiencing diminished Botox effect.
Can masseter Botox be combined with chin filler? Is the V-line effect good?
Highly recommended — masseter reduction + chin filler is the golden combination for V-line facial contouring: (1) Complementary effects — Botox reduces masseter to decrease mandibular angle width (narrowing the face), HA filler extends the chin (lengthening and pointing the face), synergistically achieving a narrow + long + pointed V-line. (2) Same-day treatment — the two target completely different areas (masseter at bilateral mandibular angles vs chin at the mandibular center), non-interfering. (3) Effect timeline — HA is instant (immediate chin extension visible), Botox takes 2-4 weeks (gradual face narrowing), with combined optimal V-line effect at 1 month. (4) The combination is far superior to either alone — masseter Botox alone only narrows but doesn’t lengthen (may make the face appear shorter); chin filler alone only lengthens but doesn’t narrow (a square face with chin filler may look even more square); the combination addresses both width and length. Rappoel’s V-line comprehensive plan is based on this principle — the most cost-effective non-surgical V-line solution.
Enlarged masseter making your face square and wide? Rappoel Coretox masseter reduction — natural facial slimming in 2 weeks!
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