Liposome-encapsulated ropivacaine for intraoral topical anesthesia.

OBJECTIVES: This study evaluated the efficacy of liposome-encapsulated 2% ropivacaine in topical anesthesia and its influence on pulpal response. STUDY DESIGN: Forty volunteers received the following topical formulations in the buccal fold of the maxillary lateral incisors region (bilaterally): liposome-encapsulated 2% ropivacaine gel (RL2); 20% benzocaine gel (B20); liposomal placebo gel (LP); and placebo gel (P). Formulations were kept in place for 30 minutes, during which time the teeth were electric pulp tested every 10 minutes. After this procedure, a dental needle was inserted until periosteum contact in the same site of topical application and pain was rated by a visual analog scale. Duration of soft tissue anesthesia was assessed by pinprick test. RESULTS: RL2 and B20 showed lower pain response to needle insertion and longer soft tissue anesthesia then P and LP (P = .0003 and P < .0001, respectively); however, RL2 was not different from B20 (P > .05) regarding those parameters. None of the formulations was able to induce pulpal anesthesia. CONCLUSION: RL2 was as effective as B20 in reducing pain during needle insertion and inducing soft tissue anesthesia; however, neither one was able to induce pulpal anesthesia after a 30-min application.

Liposomal encapsulation improves the duration of soft tissue anesthesia but does not induce pulpal anesthesia.

STUDY OBJECTIVE: To compare the topical and the pulpal anesthesia efficacy of liposomal and plain benzocaine formulations. DESIGN: Double-blinded, randomized crossover study. SETTING: University ambulatory dental center. PATIENTS: 30 ASA physical status I volunteers. INTERVENTIONS: Volunteers received, in three different sessions, topical application of liposome-encapsulated 10% benzocaine (LB10), 10% benzocaine gel (B10), and 20% benzocaine gel (B20) in the right maxillary canine mucobuccal fold. MEASUREMENTS: Pain associated with the needle insertion was rated by visual analog scale (VAS) and the duration of topical anesthesia was recorded. Pulpal anesthesia was evaluated using an electric pulp tester. MAIN RESULTS: VAS values (median, 1st - 3rd quartiles) were 17 cm (11 - 25), 14 cm (3 - 22), and 21 cm (9 - 21) for B10, LB10, and B20, respectively. No differences were noted among the groups (Friedman test; P = 0.58). Soft tissue anesthesia was also not different. The LB10 [10 (8 - 12) min] showed longer soft tissue anesthesia (Friedman test; P < 0.01) than the other agents [B10 = 8 (5 - 10) min, and B20 = 7 (6 - 9) min]. None of the topical benzocaine formulations tested induced pulpal anesthesia. CONCLUSIONS: The encapsulation of benzocaine into liposome increased the duration of soft tissue anesthesia. However, it did not induce pulpal anesthesia.

Liposome-encapsulated ropivacaine for topical anesthesia of human oral mucosa.

BACKGROUND: The elimination of pain caused by needle insertion for local anesthesia would be a significant advance in dentistry. METHODS: In this blinded cross-over study we evaluated the efficacy of liposome-encapsulated ropivacaine for topical anesthesia. Thirty healthy volunteers received 60 mg topical anesthetics: Liposome-encapsulated 1% ropivacaine, 1% plain ropivacaine, 2.5% lidocaine and 2.5% prilocaine mixture (EMLA), and 20% benzocaine gel, in the buccal fold of the upper-right canine for 2 min in different sessions. After insertion of 30-G needles, pain was rated on a visual analog scale (VAS). A pinprick test was used to measure the duration of topical anesthesia. The pulpar response was assessed by an electric pulp tester. RESULTS: VAS median and interquartile range (in cm) were 0.8 (0.4-1.5), 1.6 (0.8-2.6), 1.1 (0.3-2.7), 2.2 (0.9-2.9) for liposome-encapsulated ropivacaine, ropivacaine, EMLA, and benzocaine groups, respectively. The liposome-encapsulated ropivacaine group showed lower VAS mean values when compared with the benzocaine group (P = 0.0205). The median values and interquartile range for the duration of soft tissue anesthesia were 11 (7-14), 6.5 (4-11), 14 (11-16), and 7 (6-9) min for liposome-encapsulated ropivacaine, ropivacaine, EMLA, and benzocaine groups, respectively. EMLA and liposome-encapsulated ropivacaine were just as efficient for reducing pain, and showed longer soft tissue anesthesia when compared to the other local anesthetics (P = 0.0001). CONCLUSION: Liposomal-encapsulated 1% ropivacaine gel was equivalent to EMLA for reducing pain during needle insertion and for the duration of soft tissue anesthesia. None of the topical anesthetics was effective for inducing pulpal anesthesia.