INTRODUCTION
Local anesthesia has been defined as a loss of sensation in a circumscribed area of the body caused by depression of excitation in nerve endings or inhibition of conduction process in peripheral nerves. Local anesthetics (LA’s) are used clinically for anesthesia and analgesia either following surgery or for management of other acute and chronic pain conditions; they only last a few hours. Lignocaine is perhaps the most commonly used local anesthetic agent: it is used either in local or regional anesthesia, or in epidural or spinal blockade.1
For many years, anesthesiologists and pharmacologists have been searching for an ideal local anesthetic solution with prolonged action and low toxicity. Experiments with the piperidine ring of cocaine combined with the xylidine component of lidocaine resulted in the pipecoloxylidine family of local anesthetics which included the long acting local anesthetics; mepivacaine, bupivacaine and ropivacaine. These drugs possess enhanced lipid solubility characteristics (making them extremely potent) and display an increased affinity for protein binding which dramatically increases the duration of achievable anesthesia. This biochemical trait makes this group of drugs far more superior than their short acting analogues.2
Long acting local anesthetics not only produce localized sensory and motor anesthesia, but also provide effective postoperative pain relief and analgesia. Therefore, there are 2 primary indications for utilization of long acting local anesthetics in dentistry: (1) lengthy dental procedures for which pulpal anesthesia in excess of 90 minutes is necessary and (2) management of postoperative pain.2Long acting local anesthetics available are bupivacaine and etidocaine. Bupivacaine has more tissue toxicity, neurotoxicity and cardiotoxicity. Etidocaine is less cardiotoxic but increased intra operative bleeding is observed.3
Ropivacaine is a local anesthetic of the amide type that chemically is homologous to bupivacaine and mepivacaine. It is available in various concentrations (0.75%, 0.5%, 0.375%, or 0.25%) and is said to have inherent vasoconstrictive properties at low concentrations. Ropivacaine has 75% greater margin of safety than bupivacaine. Cardiovascular electrophysiology effects of ropivacaine were also found to be intermediate between those of lidocaine and bupivacaine. Ropivacaine is suitable local anesthetic without vasoconstrictor for nerve block anesthesia in dental practice.4
Ropivacaine is equivalent in potency and efficacy to bupivacaine. Due to its long duration of both pulpal and soft tissue anesthesia after mandibular nerve block and a lower CNS and cardiovascular toxicity, ropivacaine can be a good alternative to bupivacaine as a local anaesthetic in dental implant surgery.5Thus this study has been undertaken to compare the efficacy of ropivacaine to lignocaine with adrenaline for prolonged anesthesia and postoperative analgesia in implant surgery.