Clinical Evaluation of Inferior Alveolar Nerve Block: SUBJECTS AND METHODS

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10 Feb 2010

Insertion Angle

The insertion angles in the conventional and anterior techniques were measured using CT images of the head and neck region of patients (27 males and 38 females) stored in the Nippon Dental University Hospital. The CT images at the level near the mandibular foramen, excluding image abnormalities, were examined in 61 sites on the right and 64 sites on the left, totaling 125 sites. The predicted insertion angle in the anterior technique was determined by measuring the inside angle between the median sagittal plane and a line joining the latero-anterior border of the medial pterygoid muscle and the distal margin of the deep tendon of the temporal muscle for the insertion site on the medial side of the ramus. The predicted insertion angle in the conventional technique was determined by measuring the inside angle between the median sagittal plane and the line joining the latero-anterior border of the medial pterygoid muscle and the center of the mandibular ramus, corresponding to the mandibular foramen.

Clinical Evaluation

This study was approved by the Ethical Committee of the Nippon Dental University, School of Dentistry at Tokyo. Informed consent was obtained from 100 patients who participated in the study. The anterior technique was performed once in each patient who was scheduled for mandibular molar extraction at the anesthesiology or oral surgery outpatient departments at our affiliated hospital. The authors and 16 other oral surgeons who had received oral instruction for the technique participated in the clinical study.

To estimate the postural effects during the anesthetic procedure, the patients were randomly assigned into 1 of 2 groups, ie, the supine group (47 patients) or the sitting group (53 patients). The anterior technique was performed using a dental cartridge syringe (Self-Aspirating Syringe, ASTRA), a 30-gauge, 21-mm disposable needle, and a dental anesthetic cartridge consisting of 1.8 ml of 2% lidocaine containing 1:80,000 epinephrine. The syringe was positioned with the insertion point at the lateral side of the pterygomandibular fold approximately 10 mm above the occlusal plane and was placed over the contralateral mandibular first molar. The needle was inserted to a depth of 10 mm. After ensuring no blood aspiration, 1.8 ml of anesthetic solution was injected (Figure 1). After the patient reported numbness of the tongue and lower lip, the stick test was performed in the lower lip to confirm anesthesia. The infiltration of anesthetic to the buccal gingiva was performed and the tooth extraction commenced. If the anesthetic effect was not observed within 10 minutes, an alternate insertion angle and insertion depth was considered by the attending anesthetist.

Figure 1. Schematic diagrams show

The duration from the end of nerve block administration to the onset of numbness in the tongue and lower lip and analgesia in the lower lip, the time when tooth extraction started, and the status of supplemental injections were all recorded. The estimation of anesthetic effect was evaluated according to Dobbs and De Vier. The postural effect of the patients during anesthesia procedure was also studied. cheap cialis canadian pharmacy

Statistical analyses were performed using Statisica for MS Windows Ver. 5.05J (StatSoft) on a standard personal computer. The insertion angles were analyzed with Student’s t test, and the differences in anesthesia grade and onset time between groups were examined by the Mann-Whitney’s U test. The critical level of significance was set at P = .05. Values of clinical evaluation were presented as median and range.

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