Necessity of 3D visualization for the removal of lower wisdom teeth: required sample size to prove non-inferiority of panoramic radiography compared to CBCT

Abstract

The availability of cone beam computed tomography (CBCT) and the numbers of CBCT scans rise constantly, increasing the radiation burden to the patient. A growing discussion is noticeable if a CBCT scan prior to the surgical removal of wisdom teeth may be indicated. We aimed to confirm non-inferiority with respect to damage of the inferior alveolar nerve in patients diagnosed by panoramic radiography compared to CBCT in a prospective randomized controlled multicentre trial. Sample size (number of required third molar removals) was calculated for the study and control groups as 183,474 comparing temporary and 649,036 comparing permanent neurosensory disturbances of the inferior alveolar nerve. Modifying parameter values resulted in sample sizes ranging from 39,584 to 245,724 respectively 140,024 to 869,250. To conduct a clinical study to prove a potential benefit from CBCT scans prior to surgical removal of lower wisdom teeth with respect to the most important parameter, i.e., nerval damage, is almost impossible due to the very large sample sizes required. This fact vice versa indicates that CBCT scans should only be performed in high risk wisdom tooth removals.

Are different imaging methods affecting the treatment decision of extractions of mandibular third molars?

“…The author agrees with Roeder et al 13 and considers that CBCT scans should only be performed in high-risk wisdom tooth removals or for determination of the surgical approach and/or for coping with intraoperative complications. An effort to reduce the use of CBCT should be carried out when not necessary, in order to reduce radiation exposure and damage to the patient (Figure 4).…”

Efficacy of CBCT for assessment of impacted mandibular third molars: a review – based on a hierarchical model of evidence

“…RCTs are often time consuming and, in addition, expensive to conduct, and therefore the number of patients included is often low, resulting in underpowered studies. 66 Epidemiological studies with lower evidence levels than that of RCTs have, moreover, evaluated the relationship between the use of CBCT for assessment of mandibular third molars and nerve injuries. A register study from Finland 67 concluded that the rapid increase in the availability of CBCT has caused no reduction in the number of permanent IAN injuries related to mandibular third molar removals as reported to the Finnish Patient Insurance Centre.…”

Neurosensoric disturbances after surgical removal of the mandibular third molar based on either panoramic imaging or cone beam CT scanning: A randomized controlled trial (RCT)

“…A study from 2011 describes the almost impossible task to conduct an RCT measuring differences in permanent injuries owing to the need of very large samples. 33 Furthermore, the study highlighted that measuring differences in temporary disturbances also requires large samples. Therefore, the sample size has to be addressed and considered as a methodological limitation.…”