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.