**6. New local anesthetics**


medication on the mucosa due to its systemic absorption has not yet been approved [2]. Studies have reported that the analgesic effect of EMLA for periodontal probing and scaling is more than 5% prilocaine ointment. The use of 4 g of EMLA for the creation of analgesia is recommended for the removal of arch bars [30]. The study of Hassio in 1990 showed no difference between 10% lidocaine spray and EMLA for topical anesthesia of the gums. The level of anesthesia at 13-14 minutes measured by EMLA-apparatus was equal in both. The sensitivity of the gums returns to normal within 30 minutes. No toxic reactions were observed but it is said that the absorption of EMLA is faster than lidocaine spray [31].

**Figure 9.** EMLA

exposure of the pulp which limits the ability to use this method only in endodontic therapy

**5. Mandibular infiltration technique:** This has a high success rate in children with primary teeth but its success is reduced when children grow and the teeth change from primary to mixed dentition and mandibular cortical thickness increases. Studies have shown that this technique is more successfully with articaine 4% rather than lidocaine 2% but the mechanism is yet unknown. One theory suggests that there is a thiophene loop in articaine that provides greater penetration compared to lidocaine, which has a benzene loop [25].

**6. Topical anesthesia:** The use of topical anesthesia in dentistry or the treatment of laceration is very useful especially in children. The skin needs a larger amount of drugs for topical anesthesia because of less blood supply than mucosa. Due to the poor solubility in water and thus reducing the systemic absorption, benzocaine is the drug of choice for use on mucosal surfaces. Benzocaine Ointment (20%) is used for this purpose. The onset time is 2 to 3 minutes and the duration of anesthesia is 15 minutes. Lidocaine 5% is another common drug in this category with a similar onset and duration of anesthesia to benzocaine. Tetracaine is the strongest surface anesthetic drug that has be presented in a cold spray type in combination with 14% Benzocaine. Tetracaine is also used for endoscopic procedures and gag control [1, 2]. Topical anesthesia will not cause a completely painless injection and that depends more on the needle gauge and duration of the injection. Topical anesthesia will be helpful for

**1. LMX:** This consists of liposomal capsules containing lidocaine. Liposomes increase lidocaine absorption in a controlled pattern and prevent its systemic toxicity. This drug should be given 30 minutes before surgical intervention on the area in the amount of 1 to 2 mg, sufficient for an area of skin measuring 10 square centimeters [2]. In a study in 2002, liposomal capsules of ropivacaine were compared to EMLA for topical anesthesia of the palatal mucosa during needle entrance into the tissues in which EMLA was significantly more successful than encapsulated ropivacaine [28].Studies have shown that other anesthetic drugs such as bupivacaine provide a greater duration of anesthesia into the

**2. EMLA:** This cream is used widely for topical anesthesia to treat laceration and lumbar punctures (Figure 9). This medication contains lidocaine 2.5% and prilocaine 2.5% that penetrate well into tissues due to its micron-sized droplets. Its onset time of action depends on blood supply for the area. On the face it starts to work within 15 minutes. Its maximum depth of anesthesia is 5 mm and can be achieved within 120 minutes. So if more depth is needed we should use the usual anesthetic injection techniques. The amount of 1 to 2 mg of this drug is sufficient for an area of 10 square centimeters of skin and should be placed on the area. At least 1 hour before starting the treatment process. Use of this

periodontal examinations and very conservative treatments [27].

liposomal formulation as compared to the normal [29].

**6. New local anesthetics**

[1] or in the course of removal of impacted teeth.

18 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2


**6. Drug Combination:** The combination of local anesthetic drugs with systemic analgesic drugs such as morphine can reduce the amount of pain during and after the surgery [33]. In general, the combination of opioid with anesthetic drugs reduces the need for analgesics after surgery and increases the duration of anesthesia but has side effects such as nausea and vomiting. The combination of alpha-2 adrenergic agonists such as clonidine, espe‐ cially with medium-acting anesthetic medications, increases the potential of these drugs. The drug side effects include bradycardia, hypotension and dryness of the mouth, which of course are caused by doses greater than 2 micrograms per kilogram. Ketamine, midazolam and magnesium can increase the power of anesthetic drugs but they must also be considered for their neurotoxic properties. Symptoms such as hallucination and sedation occur following the use of these drugs [34].
