Trigeminal neuralgia (TN) is one of the most painful and common types of neuropathic pain encountered by clinicians. It is typically treated pharmacologically with anticonvulsants,but these can be ineffective, or can lose their effectiveness over time.Botulinum toxin type A (BoNT-A) is an exotoxin released by the Gram-positive, anaerobic bacillus Clostridium botulinum that causes flaccid paralysis by blocking neurotransmitter release by axonal terminals. As a contaminant, it is the cause of potentially lethal botulism poisoning; however, as a drug, it has been widely used in the treatment of dystonia, as well as for non-surgical cosmetic treatment. More recently, studies investigating the ability of BoNT-A to treat pain have been increasing. In 2012, the investigators reported the results of a randomized, double-blind, and placebo-controlled trial in which subcutaneous injection of BoNT-A at the site of pain provided long-term effective relief in TN. The investigators noted that adverse effects were mild, as well. Other studies on TN have estimated the effectiveness of BoNT-A treatment in TN to be 47-73%. However, BoNT-A treatment is still ineffective in more than 30% of patients.In this study, the investigators investigate whether different treatment methods have different efficacy and safety.

Inclusion Criteria:

• Age >18 years
• Clinical diagnosis of classical trigeminal neuralgia according to the ICHD III (beta)
• The pain involved the gingiva
• Signed informed consent prior to entering study

Exclusion Criteria:

• comorbid diseases that may be exacerbated by botulinum toxin type A (e.g., myasthenia gravis, motor neuron disease, or Lambert-Eaton syndrome).
• receiving drugs with neuromuscular junction toxicity 1 week before botulinum toxin type A treatment (e.g. quinine, aminoglycosides or penicillamine)
• had an infection of the skin or mucosa at any of the injection sites.
• psychiatric illness.
• malignancy.
• pregnancy or lactation.
• currently participating or previously participated in any investigational drug or device study within 6 months.