Reliability of CBCT and other radiographic methods in preoperative evaluation of lower third molars

Objectives: The aim of this study was to assess artefacts and their impact on cone beam CT (CBCT) image quality (IQ) after head motion simulated by a robot skull. Methods: A fully dentate human skull incorporated into a robot simulated pre-determined patient movements. Ten head motion patterns were selected based on the movement of the C-arm of the CBCT units (no motion as reference). Three CBCT units were used [a threedimensional eXam (K) (KaVo Dental GmbH, Biberach, Germany), a Promax 3D MAX (P) (Planmeca Oy, Helsinki, Finland) and a Scanora ® 3D (S) (Soredex Oy, Tuusula, Finland)]. Axial images were qualitatively assessed at three levels: mental foramen (MF), infraorbital foramen and supraorbital foramen, and artefacts characterized as stripe-like, double contours, unsharpness or ring-like. A 100 mm visual analogue scale (VAS) was used to quantitatively assess IQ. Cross-sectional images of the lower third molar and MF bilaterally were also evaluated by VAS. Four blinded examiners assessed the images. Results: For all units and motion patterns, stripe-like artefacts were the most common. The four observers agreed on the presence of at least one artefact type in 90% of the images. Axial images showed lower overall IQ after motion (VAS 5 72.4 ± 24.0 mm) than reference images (VAS 5 97.3 ± 2.6 mm). The most severe artefacts were seen at the MF level. For cross-sectional images, IQ was lowest after tremor. The mean IQ range was 74-89 and 57-90 for isolated (tilting, rotation and nodding) and combined (nodding 1 tilting and rotation 1 tilting) movements, respectively. IQ for MF was lower than for third molar for any movement except tremor. Conclusions: Head motion of any type resulted in artefacts in CBCT images. The impact on IQ depended on the region and level in the skull.

Section: Discussionmentioning

confidence: 99%

Cone beam CT image artefacts related to head motion simulated by a robot skull: visual characteristics and impact on image quality

Spin‐Neto

Mudrák²,

Matzen³

et al. 2013

“…CBCT imaging is a relatively new modality that has the advantage of displaying the bucco-oral aspect of the relation between the molar and the canal, and several studies have assessed the use of CBCT before surgical removal of mandibular third molars and found CBCT to be superior to panoramic images to display the relation between the molar and the mandibular canal. [15][16][17][18][19]25,34 However, no previous study has examined whether the treatment plan will change when CBCT is available compared with merely a panoramic image and scanograms, or which factors that have an impact on deciding on coronectomy vs surgical removal of the entire tooth.…”

Section: Discussionmentioning

confidence: 99%

“…[15][16][17][18][19] It was recently reported in a pilot study that the surgical technique was changed (removal of bone, elevator placement, tooth sectioning) when CBCT was available compared with only panoramic images before surgical removal of mandibular third molars. 20 No studies, however, have examined the impact of CBCT on treatment planning before surgical intervention of mandibular third molars.…”

mentioning

confidence: 99%

Influence of cone beam CT on treatment plan before surgical intervention of mandibular third molars and impact of radiographic factors on deciding on coronectomyvssurgical removal

Matzen¹,

Christensen²,

Hintze³

et al. 2013

Objectives: To assess the influence of cone beam CT (CBCT) on treatment plan before surgical intervention of mandibular third molars and to identify radiographic factors with an impact on deciding on coronectomy. Methods: 186 mandibular third molars with an indication for surgical intervention underwent a radiographic examination with two methods: (1) panoramic imaging in combination with stereo-scanography and (2) CBCT. After the radiographic examination a treatment plan (TP) was established: either surgical removal (Sr) or coronectomy (Co). The first TP was based on the panoramic image and stereo-scanogram, while the second TP was established after CBCT was available. Logistic regression analyses were used to identify factors predisposing for Co after CBCT. Results: Treatment was performed according to the second TP. Agreement between the first and second TP was seen in 164 cases (88%), while the TP changed for 22 teeth (12%) after CBCT. Direct contact between the third molar and the mandibular canal had the highest impact on deciding on Co [odds ratio (OR)5101.8, p , 0.001]. Direct contact was not a sufficient factor, however; thus, lumen narrowing of the canal (OR538.9-147.2, p , 0.001) and canal positioned in a bending or a groove in the root complex (OR532.8, p50.016) were additional canal-related factors for deciding on Co. Conclusion: CBCT influenced the treatment plan for 12%. Direct contact in combination with narrowing of the canal lumen and canal positioned in a bending or a groove in the root complex observed in CBCT images were significant factors for deciding on coronectomy. Dentomaxillofacial Radiology (

“…19,20 A third clinical sign for direct contact to the IAN is grooves in the root complex from the IAN, which has also been used in some studies. 23,[38][39][40][41] Accuracy of CBCT with a reference standard: The diagnostic accuracy of CBCT using a reference standard has generally been sparsely examined. One study concluded that CBCT was more reliable than PAN imaging for evaluation of number of roots, 40 and a recent study compared three methods, PAN imaging, SCAN and CBCT and found that the modalities seemed equally valuable for examination of tooth angulation, and number and morphology of roots of mandibular third molars.…”

Section: Level 2-effect On Diagnostic Accuracymentioning

confidence: 99%

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

Matzen

Wenzel²

2015

114

A radiographic examination of mandibular third molars is meant to support the surgeon in establishing a treatment plan. For years panoramic (PAN) imaging has been the first choice method; however, where an overprojection is observed between the third molar and the mandibular canal and when specific signs suggest a close contact between the molar and the canal, CBCT may be indicated. The present review provides an evaluation of the efficacy of CBCT for assessment of mandibular third molars using a six-tiered hierarchical model by Fryback and Thornbury in 1991. Levels 1-3 include studies on low evidence levels mainly regarding the technical capabilities of a radiographic method and the diagnostic accuracy of the related images. Levels 4-6 include studies on a higher level of evidence and assess the diagnostic impact of a radiographic method on the treatment of the patient in addition to the outcome for the patient and society including cost calculations. Only very few high-evidence studies on the efficacy of CBCT for radiographic examination of mandibular third molars exist and, in conclusion, periapical or PAN examination is sufficient in most cases before removal of mandibular third molars. However, CBCT may be suggested when one or more signs for a close contact between the tooth and the canal are present in the two-dimensional image-if it is believed that CBCT will change the treatment or the treatment outcome for the patient. Further research on high-evidence levels is needed. Dentomaxillofacial Radiology (