Cone-beam computed tomography: time for an evidence-based approach

Evaluation of use of cone beam computed tomography in paediatric patients: A cross-sectional study

BACKGROUND

Cone beam computed tomography (CBCT) is widely used in paediatric dentistry. Appropriate use of CBCT is important because children are more vulnerable to ionizing radiation than adults.

AIM

To investigate the use of CBCT in children by describing reasons for requesting it and its distribution according to age, oral region, and department.

DESIGN

Cone beam computed tomography scans of patients (age < 19 years) who presented to our dental clinic were investigated retrospectively according to sex, age (6-12 [Group 1] and 13-18 [Group 2] years based on dentition), referring department, imaging area (anterior/posterior, mandible/maxilla), and indication. Indications were grouped under five headings according to 2011 SEDENTEXCT guidelines: dental anomalies, impacted teeth, endodontics, bone pathosis, and others.

RESULTS

Overall, 334 CBCT scans at different times and for different reasons in 319 patients were evaluated. In recent years, CBCT requests increased in both age groups. Eighty-five CBCT scans (25.44%) of 78 patients (24.45%) with a mean age of 10.37 ± 1.60 years were examined in Group 1, whereas 249 CBCT scans (%74.55) of 241 patients (75.54%) with a mean age of 15.66 ± 1.70 years were examined in Group 2. The most frequent indication was the assessment of impacted teeth (46.1%). The anterior maxilla was the most frequently monitored region (41.6%). The oral and maxillofacial radiology department was the department that made the most CBCT requests in all the years considered (53.6%).

CONCLUSIONS

The most common indications were the assessment of dentigerous cysts and impacted teeth. There was an increase in the number of referrals to paediatric dentistry.

Comparison of Diagnostic Accuracy of Panoramic Radiography to CBCT in Maxillary Sinus Diseases

We aimed to compare the effectiveness of panoramic radiography (PR) and cone beam computed tomography (CBCT) in radiographic diagnosis of maxillary sinus (MS) diseases. MS diseases (mucosal thickening, mucus retention cyst, polyp sinusitis, mucocele and tumoral formations) was carried out on both PR and CBCT images belonging to 625 patients. Analyzes were performed separately for right and left maxillary sinus, and total of 1250 PR and CBCT images. While a diagnosis of disease was made in 42.96% of a total of 1250 MS according to CBCT. According to PR, diagnosis was made in 58.72%. The 537 diagnoses where lesion presence was determined on CBCT in our study were compared over PR, and it was observed that, there was the right diagnosis (true positive) in 106 (19.73%) of these including respectively mucus retention cyst (n = 88), polyp (n = 16), 1 sinusitis and 1 tumor, and there was an incorrect diagnosis (false positive) in 221 (41.15%). In 42.92% of the MS that were identified as healthy based on CBCT, the correct diagnosis was also made on PR (true negative). The use of CBCT instead of PR in the diagnosis of pathological or inflammatory diseases contributes to a more accurate radiographic differential diagnosis.

Anterior buccal mandibular depression: A descriptive study of CT findings

Objective

This study aims to report the concurrence of the radiographic features of anterior buccal mandibular depressions (ABMDs) and anterior lingual mandibular depressions (ALMDs) by conventional computed tomography (CT) and cone beam CT scans. We also assess the effect of ABMDs and ALMDs on dental implant sites.

Methods

A retrospective review of CT scans of the mandibles with ABMDs was conducted to assess the morphology, site, presence of foramina, ALMDs, and the integrity of the cortical plate. The superoinferior width of ABMD, the buccolingual depth, and mesiodistal length were measured and compared with the thickness of the cortical plate at the depression to the area superior to it.

Results

Thirty-seven patients with 74 ABMDs were included in this study. All observed ABMDs occurred bilaterally, and ALMDs with ABMDs occurred in 13 sites (17.56%). In 20 (54%) cases, at least one foramen was noted. The buccal cortical bone was intact in all cases. The contents of ABMDs were found to be fatty. On an average, their superoinferior width was 7.1 mm, buccolingual depth 1.67 mm, and mesiodistal length 18.8 mm. The average buccal cortical bone plate thickness at the ABMD was 1.23 mm (range 0.4-1.9 mm), while the average buccal cortical bone plate thickness coronal to the ABMD was 1.34 mm (range 0.7-2.2 mm). The average buccolingual dimension of the mandible was 8.72 mm (range 4.15-13.4 mm) at ABMD sites without ALMD and 4.6 mm with ALMD (range 1.8-8 mm).

Conclusion

When ALMD occurs in the presence of ABMD, the amount of bone available for implant placement is greatly reduced.

Applications of cone beam computed tomography in endodontics

Background

Endodontic disease can adversely affect the quality of life and therefore early diagnosis and consequent timely treatment is of paramount importance for the Endodontist. Radiology is an essential component in treatment planning, disease monitoring and assessment of treatment outcome. Periapical radiographs and panoramic radiography are frequently utilised but they provide only two-dimensional representation of three-dimensional structures. The advent of cone beam computed tomography (CBCT) offers three-dimensional accuracy of the hard tissue images with a reasonable cost and this has revolutionised imaging of the dentomaxillofacial structures. This imaging system has been seen to overcome some limitations of conventional radiography, as brought out in this review. The improvement in the accuracy is, however, accompanied at the cost of increased radiation exposure to the patient. Nevertheless, smaller areas of exposure are normally appropriate for endodontic imaging, and adjustment in the exposure parameters can further moderate the effective dose (Loubele et al. 37(6):309-18, 2008).

Aims and objectives

The aim of this review is to present the pertinent literature on the various applications of cone beam computed tomography in the field of endodontics.

Methods

Literature was electronically searched on the following sources; Medline and Keats Library. Further, a manual search was performed on the following journals: International Endodontic Journal, Journal of Endodontics, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, Endodontology, Journal of Dental Research, European Journal of Oral Sciences & Odontology and Dentomaxillofacial Radiology. A preliminary search was performed to gain an idea of the available literature using keywords ‘Cone Beam Computed Tomography’ to view the volume of the literature evident and identify questions to be addressed in this review. The initial search showed 243 potential articles. After scrutinising the titles and abstracts of the retrieved articles, 70 relevant studies were reviewed in full text. Furthermore, ‘published guidelines on the use of CBCT’ were also searched so as to include the results as an additional source material. All the articles eligible to be included in the review were in the English language and ranged from the year 1960 to the present. Also all the studies reviewed were based on the various uses of cone beam computed tomography in the field of endodontics. The keywords used to search were ‘Cone Beam Computed Tomography (CBCT)’, ‘Conventional radiography’, ‘Applications of CBCT in endodontics’, ‘CBCT and tooth morphology’, ‘CBCT and apical periodontitis’, ‘CBCT and vertical root fractures’, ‘CBCT and resorption’, ‘CBCT and pre-surgical assessment’, ‘CBCT and dento-alveolar trauma’ and ‘CBCT and endodontic outcome’.

Results

Every case is unique and CBCT should be considered only after studying each case individually. CBCT imaging needs to be adopted or used where information from conventional imaging systems is either inadequate for the management of endodontic problems or inconclusive. Having said that, it is safe to state that CBCT imaging has the potential to become the first choice for endodontic treatment planning and outcome assessment, especially when new scanners with lower radiation doses and enhanced resolution would be available.

Effect of Milliamperage Reduction on Pre-surgical Implant Planning Using Cone Beam Computed Tomography by Surgeons of Varying Experience

BACKGROUND

Differences in CBCT units and the lack of standardization result in exposure to radiation doses beyond what is required for diagnostic purposes, especially when planning the surgical placement of dental implants.

AIM

To assess the influence of low- and high-dose milliamperage settings on CBCT images for objective and subjective implant planning among senior specialists (5 years of experience) and juniors (fresh graduates).

MATERIALS AND METHODS

Two dry skulls (4 hemi-maxillary segments of the maxilla and 4 hemi-maxillary segments of the mandible) were scanned under low (2 mA) and high (6.3 mA) dosage settings using the Carestream CS 9300 machine. Cross-sectional slices of both image qualities were evaluated by the 5 seniors and the 5 juniors for subjective image utility for implant planning and for objective linear bone measurements.

RESULTS

There were no significant differences in bone measurements taken on high- or low-dose images by all seniors and by the majority of juniors (p > 0.05). In qualitative image assessments, there was independence between assessment and image quality for almost all observers. For planning posterior mandibular implant placement, increased dosage improved concordance and kappa values between low- and high-dose images for senior observers (from K = 0.287 at low dose to K = 0.718 at high does) but not for juniors (K = 0.661 and K = 0.509 for low and high dose, respectively).

CONCLUSION

Reduction in milliamperage did not affect diagnostic image quality for objective bone measurements and produced sufficient concordance for qualitative assessment. Judicious optimization of milliamperage settings based on individual diagnostic requirements can result in significant dose reduction without compromising diagnostic decision-making.

Impact of Cone Beam Computed Tomography Dose in Pre-Surgical Implant Analysis

Objectives

Cone-Beam Computed Tomography (CBCT) produces vital information required for the accurate and prudent placement of dental implants. Lack of standardization between CBCT machines may result in unsafe patient exposure to harmful radiation; higher doses are not necessarily associated with improved image quality.

Aim

The study aimed to assess the influence of low- and high-dose milliamperage settings on CBCT images for objective and subjective implant planning.

Methods

Two dry skulls (4 hemi-maxillary segments of the maxilla and 4 hemi-maxillary segments of the mandible) were scanned under low (2 mA) and high (6.3 mA) dosage settings using a CBCT (Carestream CS 9300). Cross-sectional slices of both image qualities were evaluated by five expert clinicians, for image quality for implant planning and objective bone measurements.

Results

There were no significant differences in bone measurements taken on high or low dose images (p > 0.05). In qualitative image assessments, assessment and image quality for almost all observers were independent of each other. For planning posterior mandibular implant placement, increased dosage improved concordance and kappa values between low and high dose images.

Conclusion

Reduction in milliamperage did not affect diagnostic image quality for objective bone measurements and produced sufficient intra-rater reliability for qualitative assessment; therefore dose reduction can be achieved without compromising diagnostic decision- making.

Clinical guidelines for dental cone-beam computed tomography

Dental cone-beam computed tomography (CBCT) received regulatory approval in Japan in 2000 and has been widely used since being approved for coverage by the National Health Insurance system in 2012. This imaging technique allows dental practitioners to observe and diagnose lesions in the dental hard tissue in three dimensions (3D). When performing routine radiography, the examination must be justified, and optimal protection should be provided according to the ALARA (as low as reasonably achievable) principles laid down by the International Commission on Radiological Protection. Dental CBCT should be performed in such a way that the radiation exposure is minimized and the benefits to the patient are maximized. There is a growing demand for widespread access to cutting-edge health care through Japan's universal health insurance system. However, at the same time, people want our limited human, material, and financial resources to be used efficiently while providing safe health care at the least possible cost to society. Japan's aging population is expected to reach a peak in 2025, when most of the baby boomer generation will be aged 75 years or older. Comprehensive health care networks are needed to overcome these challenges. Against this background, we hope that this text will contribute to the nation's oral health by encouraging efficient use of dental CBCT.

Endodontic procedures for retreatment of periapical lesions

BACKGROUND

When primary root canal therapy fails, periapical lesions can be retreated with or without surgery. Root canal retreatment is a non-surgical procedure that involves removal of root canal filling materials from the tooth, followed by cleaning, shaping and obturating of the canals. Root-end resection is a surgical procedure that involves exposure of the periapical lesion through an osteotomy, surgical removal of the lesion, removal of part of the root-end tip, disinfection and, commonly, retrograde sealing or filling of the apical portion of the remaining root canal. This review updates one published in 2008.

OBJECTIVES

To assess effects of surgical and non-surgical therapy for retreatment of teeth with apical periodontitis.To assess effects of surgical root-end resection under various conditions, for example, when different materials, devices or techniques are used.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Trials Register (to 10 February 2016), the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 1), MEDLINE Ovid (1946 to 10 February 2016) and Embase Ovid (1980 to 10 February 2016). We searched the US National Registry of Clinical Trials (ClinicalTrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing trials (to 10 February 2016). We placed no restrictions regarding language and publication date. We handsearched the reference lists of the studies retrieved and key journals in the field of endodontics.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) involving people with periapical pathosis. Studies could compare surgery versus non-surgical treatment or could compare different types of surgery. Outcome measures were healing of the periapical lesion assessed after one-year follow-up or longer; postoperative pain and discomfort; and adverse effects such as tooth loss, mobility, soft tissue recession, abscess, infection, neurological damage or loss of root sealing material evaluated through radiographs.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from included studies and assessed their risk of bias. We contacted study authors to obtain missing information. We combined results of trials assessing comparable outcomes using the fixed-effect model, with risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, and 95% confidence intervals (CIs). We used generic inverse variance for split-mouth studies.

MAIN RESULTS

We included 20 RCTs. Two trials at high risk of bias assessed surgery versus a non-surgical approach: root-end resection with root-end filling versus root canal retreatment. The other 18 trials evaluated different surgical protocols: cone beam computed tomography (CBCT) versus periapical radiography for preoperative assessment (one study at high risk of bias); antibiotic prophylaxis versus placebo (one study at unclear risk); different magnification devices (loupes, surgical microscope, endoscope) (two studies at high risk); types of incision (papilla base incision, sulcular incision) (one study at high risk and one at unclear risk); ultrasonic devices versus handpiece burs (one study at high risk); types of root-end filling material (glass ionomer cement, amalgam, intermediate restorative material (IRM), mineral trioxide aggregate (MTA), gutta-percha (GP), super-ethoxy benzoic acid (EBA)) (five studies at high risk of bias, one at unclear risk and one at low risk); grafting versus no grafting (three studies at high risk and one at unclear risk); and low energy level laser therapy versus placebo (irradiation without laser activation) versus control (no use of the laser device) (one study at high risk).There was no clear evidence of superiority of the surgical or non-surgical approach for healing at one-year follow-up (RR 1.15, 95% CI 0.97 to 1.35; two RCTs, 126 participants) or at four- or 10-year follow-up (one RCT, 82 to 95 participants), although the evidence is very low quality. More participants in the surgically treated group reported pain in the first week after treatment (RR 3.34, 95% CI 2.05 to 5.43; one RCT, 87 participants; low quality evidence).In terms of surgical protocols, there was some inconclusive evidence that ultrasonic devices for root-end preparation may improve healing one year after retreatment, when compared with the traditional bur (RR 1.14, 95% CI 1.00 to 1.30; one RCT, 290 participants; low quality evidence).There was evidence of better healing when root-ends were filled with MTA than when they were treated by smoothing of orthograde GP root filling, after one-year follow-up (RR 1.60, 95% CI 1.14 to 2.24; one RCT, 46 participants; low quality evidence).There was no evidence that using CBCT rather than radiography for preoperative evaluation was advantageous for healing (RR 1.02, 95% CI 0.70 to 1.47; one RCT, 39 participants; very low quality evidence), nor that any magnification device affected healing more than any other (loupes versus endoscope at one year: RR 1.05, 95% CI 0.92 to 1.20; microscope versus endoscope at two years: RR 1.01, 95% CI 0.89 to 1.15; one RCT, 70 participants, low quality evidence).There was no evidence that antibiotic prophylaxis reduced incidence of postoperative infection (RR 0.49, 95% CI 0.09 to 2.64; one RCT, 250 participants; low quality evidence).There was some evidence that using a papilla base incision (PBI) may be beneficial for preservation of the interdental papilla compared with complete papilla mobilisation (one RCT (split-mouth), 12 participants/24 sites; very low quality evidence). There was no evidence of less pain in the PBI group at day 1 post surgery (one RCT, 38 participants; very low quality evidence).There was evidence that adjunctive use of a gel of plasma rich in growth factors reduced postoperative pain compared with no grafting (measured on visual analogue scale: one day postoperative MD -51.60 mm, 95% CI -63.43 to -39.77; one RCT, 36 participants; low quality evidence).There was no evidence that use of low energy level laser therapy (LLLT) prevented postoperative pain (very low quality evidence).

AUTHORS' CONCLUSIONS

Available evidence does not provide clinicians with reliable guidelines for treating periapical lesions. Further research is necessary to understand the effects of surgical versus non-surgical approaches, and to determine which surgical procedures provide the best results for periapical lesion healing and postoperative quality of life. Future studies should use standardised techniques and success criteria, precisely defined outcomes and the participant as the unit of analysis.

Evaluation of canalis basilaris medianus using cone-beam computed tomography

The aim of this report is to present two cases of canalis basilaris medianus as identified on cone-beam computed tomography (CBCT) in the base of the skull. The CBCT data sets were sent for radiographic consultation. In both cases, multi-planar views revealed an osseous defect in the base of the skull in the clivus region, the sagittal view showed a unilateral, well-defined, non-corticated, track-like low-attenuation osseous defect in the clivus. The appearance of the defect was highly reminiscent of a fracture of the clivus. The borders of osseous defect were smooth, and no other radiographic signs suggestive of osteolytic destructive processes were noted. Based on the overall radiographic examination, a radiographic impression of canalis basilaris medianus was made. Canalis basilaris medianus is a rare anatomical variant and is generally observed on the clivus. Due to its potential association with meningitis, it should be recognized and reported to avoid potential complications.

Use of cone beam CT in children and young people in three United Kingdom dental hospitals

BACKGROUND

There is limited evidence about the use of cone-beam computed tomography (CBCT) in paediatric dentistry. Appropriate use of CBCT is particularly important because of greater radiation risks in this age group.

AIM

To survey the use of CBCT in children and young people in three Dental Hospitals in the United Kingdom (UK), with special attention paid to aspects of justification and optimisation.

DESIGN

Retrospective analysis of patient records over a 24-month period, looking at CBCT examinations performed on subjects under 18 years of age. Clinical indications, region of interest, scan field of view (FoV), incidental findings and exposure factors used were recorded.

RESULTS

There were 294 CBCT examinations performed in this age group, representing 13.7% of all scanned patients. CBCT was used more frequently in the >13 year age group. The most common use was for localisation of unerupted teeth in the anterior maxilla and the detection of root resorption. Optimisation of X-ray exposures did not appear to be consistent.

CONCLUSIONS

When planning a CBCT service for children and young people, a limited FoV machine would be the appropriate choice for the majority of clinical requirements. It would facilitate clinical evaluation of scans, would limit the number of incidental findings and contribute to optimisation of radiation doses.

A new method to assess the accuracy of a Cone Beam Computed Tomography scanner by using a non-contact reverse engineering technique

AIM

Today Cone Beam Computed Tomography (CBCT) has become an important image technique for dento-maxilla facial applications. In the paper a new method to assess the geometric accuracy of these systems was proposed. It uses a free form benchmark model and a non-contact Reverse Engineering (RE) system.

METHOD

The test geometry chosen for this study was designed in such a way that it simulated human spongy bone, cortical bone, gingiva and teeth and it composed of removable free form parts. It was acquired with a high-resolution laser scanner (D700 Scanner - 3Shape, Denmark). The reference 3D surface models obtained with the laser scanner was compared with the 3D models that were created from a CBCT system (Scanora 3D - Soderex, Finland) and from a traditional Multi-Slice Computed Tomography (MSCT) scanner (LightSpeed VCT 64 Slice - General Electric, USA) at different reconstruction settings, using an iterative closest point algorithm (ICP) in Geomagic(®) software.

RESULTS

The comparison between the different pairs of CAD models clearly shows that there is a good overlap between the models.

CONCLUSIONS

Although the results obtained in this study could lead to increase the use of CBCT for an increasing number of dental procedures, the publication of the European Commission guidelines represents a baseline on which the clinicians should rely heavily when considering the use of CBCT in their practice.

CLINICAL SIGNIFICANCE

The results of this research show that the accuracy of CBCT 3D models is comparable to MSCT 3D models.