The purpose of this prospective, randomized, single-blind study was to compare the anesthetic efficacy of 3.6 mL of 4% articaine with 1:100,000 epinephrine to 1.8 mL 4% articaine with 1:100,000 epinephrine in mandibular buccal infiltration injections given next to the first molar. Using a cross-over design, 86 adult subjects (43 males and 43 females) randomly received two primary buccal mandibular infiltration injections given next to the first molar of 3.6 mL of 4% articaine with 1:100,000 epinephrine and 1.8 ml of 4% articaine with 1:100,000 epinephrine, in two separate appointments, spaced at least one week apart. The second molar through the first premolar were tested with an electric pulp tester every 3 minutes for a total of 90 minutes. The pain of injection and any postoperative discomfort over the next three days was rated by the subjects on a Heft-Parker visual analogue scale.
Each test tooth had a higher percentage of 80/80 readings for each test time when the 3.6 mL volume was injected. Anesthetic success was defined as two consecutive 80/80 reading at any point during the testing time. The incidence of anesthetic success was 65.1% and 48.8% of second molars, 75.6% and 52.3% of first molars, 92.9% and 87.1% of second premolars, and 91.9% and 81.4% of first premolars for Group 1 (3.6 mL volume) and Group 2 (1.8 mL volume), respectively: There was no statistically significant difference in anesthetic success between Groups 1 and 2 for the second premolar (p=0.1797), but the second molar, first molar, and first premolar were significantly different (p=0.0129, <0.0001, and =0.0234, respectively).
The incidence of anesthetic failure was 34.9% and 51.2% in the second molars, 24.4% and 47.7% in the first molars, 7.1% and 12.9% in the second premolars, and 8.1% and 18.6% in the first premolars for Group 1 and Group 2, respectively. There was no statistically significant difference between Groups 1 and 2 for the second premolar (p=0.1797), but the second molar, first molar, and first premolar were significantly different (p=0.0129, <0.0001, and =0.0234, respectively).
The percentages of short duration of anesthesia was significantly higher for second molar, first molar, second premolar, and first premolar in group 2 (1.8 mL volume) compared to group 1 (3.6 mL volume) (p=0.0215, 0.0068, <0.0001, and =0.0001, respectively). There were no significant differences between Groups 1 and 2 for any of the four teeth tested for slow onset of anesthesia or for incidences of non-continuous anesthesia.
There were no significant differences in pain ratings between the two volumes for needle insertion, needle placement, or anesthetic deposition. The 3.6 mL volume had significantly higher pain ratings at each post-operative period, but the average pain ratings were still in the mild category.
In conclusion, the anesthetic efficacy of 3.6 mL of 4% articaine with 1:100,000 epinephrine was superior to 1.8 mL of 4% articaine with 1:100,000 epinephrine in a single primary mandibular buccal infiltration injection given next to the first molar.