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From the *Department of Physiological Sciences, Dentistry School of Piracicaba, Piracicaba, SP, Brazil; and
Department of Biochemistry, Institute of Biology, State University of Campinas– UNICAMP, Campinas, SP, Brazil.
Address correspondence and reprint requests to Francisco C. Groppo, PhD, Av. Limeira, 901 – Bairro Areião, CEP: 13414-903 Piracicaba, São Paulo, Brazil. Address e-mail to fcgroppo{at}fop.unicamp.br.
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.
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