Evaluation of a new radiographic technique: outcome following removal of mandibular third molars

Can preoperative imaging help to predict postoperative outcome after wisdom tooth removal? A randomized controlled trial using panoramic radiography versus cone-beam CT

OBJECTIVES

The primary objective of the study was to compare the postoperative complications following surgical removal of impacted third molars using panoramic radiography (PAN) images- and cone-beam computed tomography (CBCT)-based surgeries for "moderate-risk" cases of impacted third mandibular molars. The secondary objective was to compare the reliability of CBCT with that of PAN in preoperative radiographic determination of the position of the third molar, number of roots, and apical divergence.

MATERIALS AND METHODS

A randomized controlled multicenter trial was conducted to compare the surgical complications of PAN- and CBCT-based surgeries of impacted third molars. The sample consisted of impacted third molars from 256 patients with a close relation to the inferior alveolar nerve (IAN). Exclusion criteria were "no risk" and "high risk" of damage to the IAN based on the assessment of the panoramic radiograph. Patients were divided into two groups: the CBCT group (n = 126) and the PAN group (n = 130). The incidences of IAN sensory disturbance and other postoperative complications were recorded for each group at 7 days after surgery. Statistical analysis (kappa values) was used to compare the diagnoses of five trained dentomaxillofacial radiologists and to relate radiologic diagnoses to perioperative findings. Logistic regression was used to determine whether the imaging modality influenced occurrence of postoperative complications.

RESULTS

Two extractions (1.5%) in the CBCT group and five (3.8%) in the PAN group resulted in IAN sensory disturbance (p = 0.45). Logistic regression models did not show that CBCT modality decreased postoperative complications following surgical removal of impacted third molars. Yet, CBCT revealed the number of roots and apical divergence of the roots more reliably than panoramic radiographs.

CONCLUSIONS

CBCT was not better than panoramic radiography in predicting postoperative complications for moderate-risk cases of impacted third mandibular molars. Nonetheless, a CBCT buccolingual view can accurately confirm the number of roots and root morphology of the third molar better than PAN.

CLINICAL RELEVANCE

For management of postoperative complications for moderate-risk cases of impacted mandibular third molars, careful preoperative radiographic planning followed by an atraumatic surgical approach seems to be valuable, irrespective of the 2D or 3D nature of the preoperative images.

Correlation of panoramic radiographs and spiral CT scan in the preoperative assessment of intimacy of the inferior alveolar canal to impacted mandibular third molars

Iatrogenic origin of neurosensory dysfunction is a distressing sequel to the surgical removal of impacted mandibular third molars, which is frequently overlooked. According to various surveys, the rate of neurologic complications related to the surgical removal of impacted mandibular third molars varies between 0.5% and 1% for permanent damage and 5% and 7% involving temporary damage. Prevention always stands as the best modality to avoid patient's discomfort and lawsuits by sophisticated consumerism.Preoperative assessment of the topographic relationship of the impacted mandibular third molar to the inferior alveolar canal has been performed by different imaging modalities. However, none of the imaging techniques give cent percent information. The best available imaging modality in time and resources should be adopted by the surgeon to avoid complications and lawsuits. Orthopantomography has often been cited as the imaging modality of choice before surgical removal of impacted mandibular third molar. However, it depicts a two-dimensional view of an intricate three-dimensional anatomic relationship and also fails to accurately project the buccolingual relation between the tooth and the inferior alveolar canal. The current study was designed to evaluate the potential advantages of spiral computed tomography and compare its efficacy as a presurgical planning tool with orthopantomography in patients with impacted mandibular third molars showing proximity to the inferior alveolar canal on an orthopantomogram.

Patient discomfort and retakes in periapical examination of mandibular third molars using digital receptors and film

OBJECTIVE

The aim was to compare patient discomfort and evaluate the frequency of retakes using intraoral digital receptors and conventional film for radiographic examination of mandibular third molars.

STUDY DESIGN

Both mandibular third molar regions were examined in 110 patients with 2 of 5 digital intraoral receptors. Discomfort was scored on a visual analog scale (VAS) for each receptor and for film as a reference. If the whole tooth was not imaged on the digital image, a retake was performed using film. t Tests evaluated differences in VAS score, chi-squared tests evaluated differences in frequency of remakes, and logistic regression analyses evaluated factors predisposing for retake.

RESULTS

No significant difference existed in VAS scores between right and left sides for film (P = .24). The digital receptors were more uncomfortable than film (P < .001), and CDR-APS was more uncomfortable than Digora (P = .049) and Vista (P = .002). The frequency of retakes was higher for solid-state sensors than photostimulable phosphor plates (PSPs) (P < .018). Gender (P = .022), type of receptor (P < .021), and VAS score (P = .001) were predisposing factors for a retake.

CONCLUSION

Patients accepted film better than digital intraoral receptors, and retake frequency was lower for PSPs compared with solid-state sensors.

Diagnostic ability of extraoral tuned aperture computed tomography (TACT) for impacted third molars

OBJECTIVES

The purpose of this study was to evaluate the capabilities of a newly developed extraoral TACT system for diagnosing impacted third molars.

STUDY DESIGN

Three dry human mandibles with impacted third molars were used. Nine base images were obtained by the extraoral and intraoral TACT methods. Four board-certified oral and maxillofacial radiologists evaluated TACT slice images as to whether the TACT images could clearly show the periodontal space of the impacted third molar, and the location of the tooth relative to the second molar, or to the mandibular canal. The criteria were excellent, good, fair, poor, and unreadable.

RESULTS

Only the visibility of the periodontal space in extraoral TACT was significantly inferior to that of intraoral TACT. Almost all of the series of TACT images, however, were graded as excellent or good.

CONCLUSION

The results indicate that extraoral TACT is a useful modality for the clinical assessment of impacted third molars.

The relationship between radiologic interpretation and root tip fracture during tooth extraction performed by junior clinicians

OBJECTIVES

The purpose of this study was to analyze the relationship between root tip fracture and radiologic interpretation of root morphology on periapical radiographs during third molar extraction performed by junior clinicians.

METHODS

Before tooth extraction, periapical radiographs of 107 patients with 116 third molars were evaluated by junior clinicians, all with less than 5 years of clinical experience. Radiologic interpretations of root morphology-including number, curvature, fusion, and accessory root-were recorded before each extraction. The clinicians were also asked to estimate the possibility of root fracture on a Visual Analogue Scale before the procedure. The exact morphology of the extracted teeth was recorded after the extraction for the purpose of comparison.

RESULTS

Twenty-nine of 116 teeth extracted were not correctly interpreted in at least 1 of the morphologic categories surveyed. The average expected fracture rate of nonfractured teeth was 23.1%, whereas the average expected fracture rate of fractured teeth was a significantly higher 50.3%. Misinterpretation of root morphology on radiographs decreased with increased clinical experience. Senior residents had the lowest misinterpretation and fracture rate. Logistic regression analysis showed that fracture is most closely related to the estimated fracture rate (4.95) and is also significantly related to underestimation of root curvature (0.95; 24.56 with 2 df of chi-square, P = .0001).

CONCLUSIONS

Misinterpretation of root morphology on radiographs occurred in 25% of the teeth. Root curvature was the most misinterpreted item studied. Fracture was most closely related to the estimated fracture rate. Junior clinicians in this study expected that only 50% of the fractured teeth would fracture, reflecting a general underestimation of root tip fracture. Further study should be performed to evaluate how to increase the accuracy of root curvature interpretation.