title: Faster onset and more comfortable injection with alkalinized 2% lidocaine with epinephrine 1:100,000.
abstract: BACKGROUND
  The pH of lidocaine with epinephrine in dental cartridges ranges between 2.9 and 4.4. In this pH range, less than 0.1% of the anesthetic is in the de-ionized or "active" form. The acidity of the anesthetic may delay onset and contribute to injection pain.
  
  
  OBJECTIVE
  The study compared anesthetic latency and injection pain for alkalinized versus non-alkalinized anesthetic in inferior alveolar nerve blocks (IANBs).
  
  
  METHODS
  The study buffered the anesthetic directly in the cartridges using a mixing pen device. The study included 20 participants, each receiving one control and one test IANB injection. The control solution was non-alkalinized 2% lidocaine/epinephrine 1:100,000 at pH 3.85. The test solution was 2% lidocaine/ epinephrine 1:100,000 alkalinized to pH 7.31. Latency was measured using endodontic ice confirmed with an electric pulp tester (EPT), and injection pain was measured using a visual analog scale (VAS). ONSET TIME: With the alkalinized anesthetic, 71% of participants achieved pulpal analgesia in 2 minutes or less. With non-alkalinized anesthetic, 12% achieved pulpal analgesia in 2 minutes or less (P = 0.001). The average time to pulpal analgesia for the non-alkalinized anesthetic was 6:37 (range 0:55 to 13:25). Average time to pulpal analgesia for alkalinized anesthetic was 1:51 (range 0:11 to 6:10) (P = 0.001). INJECTION PAIN RESULTS: 72% of the participants rated the alkalinized injection as more comfortable, 11% rated the non-alkalinized injection as more comfortable, and 17% reported no preference (P = 0.013). Forty-four percent of the patients receiving alkalinized anesthetic rated the injection pain as zero ("no pain") on a 100-mm VAS, compared to 6% of the patients who received non-alkalinized anesthetic (P = 0.056).
  
  
  CONCLUSIONS
  Alkalinizing lidocaine with epinephrine toward physiologic pH immediately before injection significantly reduces anesthetic onset time and increases the comfort of the injection.
  
  
  CONCLUSIONS
  Clinicians can begin procedures more quickly and give a more comfortable injection by alkalinizing their lidocaine/epinephrine immediately before delivering the injection.
authors.affiliation: Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA.
authors.forename: Stanley F
authors.initials: SF
authors.lastname: Malamed
authors.forename: Susan
authors.initials: S
authors.lastname: Tavana
authors.forename: Mic
authors.initials: M
authors.lastname: Falkel
mesh_terms: D000328:Adult; D000368:Aged; D000468:Alkalies; D000766:Anesthesia, Dental; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002021:Buffers; D018592:Cross-Over Studies; D003782:Dental Pulp / Q000187:drug effects / Q000294:innervation; D003791:Dental Pulp Test; D004311:Double-Blind Method; D004837:Epinephrine / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007267:Injections / Q000009:adverse effects; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D008340:Mandibular Nerve / Q000187:drug effects; D008875:Middle Aged; D009407:Nerve Block / Q000009:adverse effects / Q000379:methods*; D010146:Pain / Q000517:prevention & control; D010147:Pain Measurement; D011446:Prospective Studies; D011930:Reaction Time / Q000187:drug effects; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D000468:Alkalies; D000779:Anesthetics, Local; D002021:Buffers; D014662:Vasoconstrictor Agents; D008012:Lidocaine; D004837:Epinephrine