Topical anesthesia is the a mechanism used in surgery to relieve pain, it involves application of aqueous solutions of local anaesthetics on the body surface so as to numb it. Dental topical anaesthesia is also used to reduce the soft tissue pain associated with application of local anaesthetics as well as in relieving gum pain resulting from irritation of soft tissues as well as teething. It is known to be one of the anesthesia options without needles.
Dental topical anesthetics are available in forms such as gel, liquid and spray, they vary according to the application. Dental topical anaesthesia mainly involves Benzocaine and Lidocaine elements, which are used to relieve mouth problems such as toothache, sore gums and mouth/gum injuries. Dental topical anaesthetics should not be used without prescription from the doctor or pharmacist. They should not be used for more than four times a day unless instructed by the doctor. On application, the medicine should be allowed to stay on the affected part for at least one minute without spitting it out. 
However, this dental topical anesthesia has side effects. The dental topical anesthesia medication should not be introduced to the eye since it is extremely harmful. The side effects of dental topical anesthesia include;tingling, slight burning as well as stinging. It also causes a rare fatal problem known as blood disorder which may occur to people having blood diseases and breathing problems. The symptoms of this blood disorder include;dizziness, headache,breath shortness as well as pale skin, in case of these symptoms, seek medical attention promptly.
Dental topical anesthesia has rare allergic reactions, but if they occur symptoms such as severe dizziness, rash, breathing troubles and itching of the tongue and throat are evident. When you detect these symptoms, seek medical attention in no time.
In conclusion, dental topical anaesthesia is good for treating oral problems but should not be used without seeking advice from the doctor/pharmacist.