Bilateral vs Unilateral IAN block anesthesia

Resident: Swan
Article Title: Bilateral versus unilateral mandibular block anesthesia in a pediatric population
Author: College, et al.
Journal: Pediatric Dentistry
Volume (Number): 22:6 2000
Major Topic: Post-operative soft tissue trauma in patients with uni- compared to bilateral block anesthesia

Main Purpose: Address the widely held belief that bilateral mandibular block anesthesia should be avoided when treating pediatric patients because of an increased risk of postoperative soft tissue trauma or other complications.

Overview of method of research: In this study, n=320, which the authors determined to be a sufficient number assuming a 9% difference in trauma frequency between unilateral vs bilateral injection groups. With a difference this large, the results would be statistically significant. Patients for this study were taken from private practices in Colorado and from two postgraduate pediatric clinics affiliated with the University of Michigan (Go Blue.) Any child planned for operative treatment requiring mandibular block anesthesia was eligible for the study. Each child was placed in either the control groups (unilateral block) or experimental group (bilateral) based on the location of necessary treatment. Both written and oral post-operative instructions were given to parents and patients. Parents left the office with a preview of the phone survey questions they would be asked later, in order to better observe their child post-operatively.
“Soft tissue trauma” was defined on the survey as redness and/or swelling on the lip, cheek, or tongue. Other questions asked: difficulty with speech or drooling, time of first meal after tx, and parents’ opinion as to whether the child accepted the numbness sensation or not. The parents were called within two days and the questionnaire was completed with each. Data collection was completed within a week following the appointment.

Findings: Subjects ranged in age from 18 mo. to 18 years, and they were divided into 4 age groups to analyze possible trends. 38 were <4 years old, 121 were 4-7, 93 were 8-11, and 68 were 12+. There was an even distribution of experimental and control patients.
16% of all patients experienced drooling, 32% had some difficulty with speech after treatment. 70% had their first meal within 2 hours after the appointment. A total of 43/320 (13%) experienced soft tissue trauma with either type of anesthesia. 18% of parents thought their children didn’t accept the numbness sensation favorably. There were no statistically significant correlations between the prevalence of soft tissue trauma and any of the parameters surveyed (age, gender, behavior, sedation type, anesthetic type/amount/site)
The highest percentage of trauma (18%) was reported in patients <4 yrs old; the percentage decreased with increasing age. The overall frequency of soft tissue trauma was higher in the unilateral anesthesia groups in 3 of the 4 age groups, (4-7 was the exception). 16% of the unilateral and 11% of the bilateral group experienced trauma. The only statistically significant finding was the incidence of trauma in the <4 age groups. 7/32 experienced trauma and 6/7 were unilaterally anesthetized.

Key Points/Summary: This is the first study to report data on complications of mandibular nerve block in pediatric patients. No significant correlation was observed between postoperative trauma and either unilateral or bilateral nerve block. The reported frequency of soft tissue trauma was much higher than that predicted by previously surveyed pediatric dentists (parents’ subjective observations?) Dentists surveyed reported 4% estimated incidence, while this study found 13% overall. Younger kids had more soft tissue trauma as one might expect. There was a tendency for the unilateral group to experience MORE soft tissue trauma than the bilateral (possibly due to lack of symmetry that exists during unilateral anesthesia). Main take home point: In regard to the factors studied, there is no contraindication to the use of bilateral IAN block when treatment needs dictate.

Assessment of Article: Interesting study posing a question that I’ve wondered myself. There are several obvious limitations that make it hard to widely apply its findings:
1) small number in the smallest age group (38), the only group with statistically significant findings
2) 18 patients were sedated (conscious sedation) during treatment. 14 of them were in the <4 yrs age group. Sedated patients tend to be groggy and want to sleep after treatment, which may lessen their tendency to traumatize their soft tissue. Sedation is a potentially confounding variable.
3) the bilateral group most likely had more work to be done, longer treatment appointments, more time to anesthesia to wear off before dismissing the patient.
4) the study relied heavily on parents’ subjective evaluations of their children’s postoperative state.
Weaknesses aside, this article definitely gave me more confidence to administer bilateral anesthesia.