A new volumetric CT machine for dental imaging based on the cone-beam technique: preliminary results

Periodontal phenotype: A review of historical and current classifications evaluating different methods and characteristics

OBJECTIVE

To review the historical and current periodontal phenotype classifications evaluating methods and characteristics. Moreover, to identify and classify the methods based on periodontal phenotype components.

OVERVIEW

Several gingival morphology studies have been frequently associated with different terms used causing confusion among the readers. In 2017, the World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions recommended to adopt the term "periodontal phenotype". This term comprises two terms, gingival phenotype (gingival thickness and keratinized tissue width) and bone morphotype (buccal bone plate thickness). Furthermore, gingival morphology has been categorized on "thin-scalloped", "thick-scalloped" and "thick-flat" considering the periodontal biotype. However, by definition, the term phenotype is preferred over biotype. Periodontal phenotype can be evaluated through clinical or radiographic assessments and may be divided into invasive/non-invasive (for gingival thickness), static/functional (for keratinized tissue width), and bi/tridimensional (for buccal bone plate thickness) methods.

CONCLUSIONS

"Thin-scalloped," "thick-scalloped," and "thick-flat" periodontal biotypes were identified. These three periodontal biotypes have been considered in the World Workshop but the term periodontal phenotype is recommended. Periodontal phenotype is the combination of the gingival phenotype and the bone morphotype. There are specific methods for periodontal phenotype evaluation.

CLINICAL SIGNIFICANCE

The term periodontal phenotype is currently recommended for future investigations about gingival phenotype and bone morphotype. "Thin-scalloped," "thick-scalloped," and "thick-flat" periodontal phenotypes can be evaluated through specific methods for gingival thickness, keratinized tissue width, and buccal bone plate thickness evaluation.

Comparison of radiographical characteristics and diagnostic accuracy of intraosseous jaw lesions on panoramic radiographs and CBCT

OBJECTIVE

To investigate the differences in imaging characteristics and the diagnostic accuracy of 225 intraosseous jaw lesions on panoramic radiographs (PAN) versus cone beam computed tomography (CBCT).

METHODS

225 sets of PAN and CBCT images with biopsy-proven histopathological diagnoses were retrospectively compared in terms of radiographic features and diagnostic accuracy. The imaging characteristics of PAN and CBCT were independently evaluated by two oral and maxillofacial radiologists who were required to answer 12 questions and provided up to three differential diagnoses with their confidence scores.

RESULTS

Odds ratios (ORs) were statistically significant for border cortication (OR = 1.521; p = .003) and border continuity (OR = 0.421; p = .001), involvement on neurovascular canals (OR = 2.424; p < .001), expansion (OR = 7.948; p < .001), cortical thinning (OR = 20.480; p < .001) as well as its destruction (OR = 25.022; p < .001) and root resorption (OR = 2.477; p < .001). Furthermore, imaging features in the posterior and mandibular regions showed better agreement than those in the anterior and maxillary regions, respectively. The diagnostic accuracy of the first differential diagnosis was higher on CBCT than on PAN (Observer 1:78.7 vs 64.4%; Observer 2: 78.7 vs 70.2% (p < .001)). The observers' confidence scores were also higher at CBCT interpretation compared with PAN.

CONCLUSIONS

CBCT demonstrated a greater number of imaging characteristics of intraosseous jaw lesions compared with PAN, especially in the anterior regions of both jaws and in the maxilla. Diagnostic accuracy is improved with CBCT compared to PAN, especially for lesions in the maxilla. Radiologists have greater confidence when using CBCT.

Accuracy of computer-guided implantation in the placement of one-piece ceramic dental implants in the anterior region: A prospective clinical study

Purpose

Placement of one-piece ceramic dental implants requires precision, which can be enhanced by using a computer-guided system. This prospective clinical study examines the accuracy of partially guided implantation in the placement of one-piece ceramic implants in the anterior region.

Materials and methods

One-piece ceramic dental implants were placed in 20 patients who were missing a central or lateral incisor. Partially guided dental implant placements were performed in all cases. The deviations in the implant positions were analyzed by superimposing post-operative cone beam computed tomography images over pre-operative treatment planning images. The results were reported as deviations (mean ± standard deviation) for three aspects (3D offset, mesio-distal, labio-lingual, and apico-coronal) and in three dimensions (the angle, coronal, and apical parts).

Results

Implants were successfully placed in 20 patients. The mean angular deviation was 4.23±1.84°, whereas the mean coronal 3D offset was 0.98±0.48 mm, and the mean apical 3D offset was 1.57±0.46 mm.

Conclusions

A prospective clinical study involving 20 patients was conducted to measure the accuracy of computer-guided implantation of one-piece ceramic dental implants. Accuracy was determined by comparing the planned implant position to the actual position. Greater accuracy can be expected at the coronal part than at the apical part. The coronal 3D offset was found to be the most accurate.

[Experimental study on the feasibility of low-dose cone beam computed tomography scanning]

OBJECTIVE

The effects of different tube currents and voltages on image quality and radiation dose were studied to provide a theoretical basis for low-dose cone beam computed tomography (CBCT) scanning in children.

METHODS

Different tube currents and voltages were used to scan the incisor area of fresh Bama pig heads by CBCT. The radiation dose was recorded, and image quality was evaluated.

RESULTS

As the tube current or voltage decreased, the radiation dose and image quality gradually decreased. The computed tomographic dose index (CTDIvol) of 90 kV, 2.5 mA and 60 kV, 7.0 mA were all 1.7 mGy. The image quality score of the former was higher than that of the latter, and the difference between them was statistically significant (P<0.05).

CONCLUSIONS

Low-dose CBCT scanning appears to be able to reduce the necessary tube current during imaging by improving image quality.

Frontal sinus: is it a predictor for vertical malocclusions?

The aim of the present study was to evaluate 3D frontal sinus morphology in consideration with different vertical facial developments. The study was conducted with the pre-treatment CBCT images of 87 patients, who were divided into 3 groups according to the sum of the posterior angle. The frontal sinus measurements were performed on the axial, sagittal, and coronal sections of the CBCT images. Craniofacial measurements were performed on the lateral cephalograms, obtained from the CBCT scans. Normal distribution of the data was confirmed by the Kolmogorov-Smirnov test. ANOVA, followed by post hoc Duncan tests, was used to compare the differences among the three groups. The relationships between sinus dimensions and craniofacial parameters were assessed by the Pearson's correlation coefficient (P < 0.05). The maximum anterior-posterior dimension of the frontal sinuses (0.017), the width of the right (0.020) and left (0.041) frontal sinuses, and the anterior-posterior dimension of the left (0.038) frontal sinus were significantly smaller in the hyperdivergent group compared to hypodivergent group. There was no significant difference between groups in terms of the height of the frontal sinuses. Significant correlation was noted between the maximum anterior-posterior dimension of the frontal sinus and SN-PP, N-Me, N-ANS, SN-GoGn, Post. sum, and Jarabak's ratio. No significant correlation between the height of the frontal sinuses and the craniofacial measurements was found. Individuals with vertical growth pattern presented decreased anterior-posterior dimension of the frontal sinuses, revealing significant correlations with vertical craniofacial parameters.

Evaluation of Upper Airway in Children with Obstructive Sleep Apnea Using Cone-Beam Computed Tomography

OBJECTIVE

Cone-beam computed tomography (CBCT) offers three-dimensional structures in assessing upper airway of patients. This study aims to compare the cone-beam computerized tomography scan measurements between children with obstructive sleep apnea (OSA) and primary snoring.

STUDY DESIGN

Case-control study.

METHODS

This prospective study was conducted in a tertiary referral center. Thirty-six children with moderate-to-severe OSA (with apnea-hypopnea index [AHI] > 5 events/hour) and 36 age-, gender-, and obesity-matched children with primary snoring (AHI <1) were enrolled. The measurements in CBCT parameters were compared between children with moderate-to-severe OSA and primary snorers by conditional logistic regression model.

RESULTS

A total of 72 children (mean age, 7.9 ± 2.8 years; 64% male) were included. Children with moderate-to-severe OSA had a significantly smaller nasopharyngeal (2900 ± 1400 vs. 3800 ± 1800 mm³ , P = .017) and oropharyngeal airway volume (5600 ± 2700 vs. 7400 ± 4000 mm³ , P = .026) than those with primary snoring. Children with moderate-to-severe OSA, as compared to primary snorers, also had a significantly smaller minimal airway area in nasopharynx (77.4 ± 37.7 vs. 107.7 ± 52.0 mm² , P = .006) and oropharynx (66.6 ± 61.9 vs. 101.6 ± 65.8 mm² , P = .023). Moreover, the airway length was not significantly different between children with moderate-to-severe OSA and primary snoring.

CONCLUSIONS

The three-dimensional CBCT airway analysis could be used as a useful tool to evaluate upper airway in children with OSA.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:680-685, 2021.

Outcomes of different radioprotective precautions in children undergoing dental radiography: a systematic review

PURPOSE

To evaluate the effectiveness of all radioprotective measures in underage patients who undergo a dental radiodiagnostic examination.

METHODS

A systematic review was performed including randomised controlled trials (RCTs), or cluster trials, cohort studies, cross-sectional studies, case-control studies and comparative in vitro research. These studies examined the healthy underage human population (below 18 years) undergoing a dental radiodiagnostic examination. All radioprotective measures were included except for justification as an intervention. The primary outcomes were in vivo mortality and morbidity. Some surrogate or indirect outcomes such as in vitro effective dose and organ absorbed doses were also accepted. Secondary outcomes with regards to image quality and therapeutic value were also analysed.

RESULTS

Eighteen papers were eligible for implementation. Fifteen studies underwent narrative synthesis. Regression analysis was performed on three studies.

CONCLUSION

The following radioprotective measures can reduce the exposure dose. For lateral cephalometry: collimation, filtration, the fastest receptor type and circumstantial thyroid shielding. For oblique lateral radiographs: the shortest exposure time, a smaller horizontal angulation, a longer focus to skin distance. For intraoral radiography: rectangular collimation, the fastest image receptor speed and thyroid shielding when the thyroid gland is in line of or very close to the primary beam. For panoramic radiographs: collimation, the fastest receptor type and the use of automatic exposure control (AEC) or manual adjustment of intensity. For cone-beam computed tomography: collimation, the largest voxels size in relation to the treatment need, change in image settings such as ultra-low dose settings, shorter exposure time, a lower amount of projections, lower beam intensity, reduction of the potential, use of a thyroid shield except in two situations and the use of AEC. All of the changes in exposure parameters should be performed while maintaining a sufficient therapeutic value on an individual and indication-based level.

Cone beam computed tomography in dentomaxillofacial radiology: a two-decade overview

OBJECTIVES

The aim of this study was to evaluate and summarise features of currently and formerly available cone beam CT (CBCT) devices from 1996 to 2019. Additionally, a recommendation for standardised reporting of CBCT characteristics was provided.

METHODS AND MATERIALS

Information about the features of all available CBCT devices was obtained from the manufacturers' available data. Moreover, site visits to newly developed CBCT machines' manufacturers were performed in order to obtain relevant information.

RESULTS

A total of 279 CBCT models from 47 manufacturers located in 12 countries (Brazil, China, Denmark, Finland, France, Germany, Italy, Japan, Republic of Korea, Slovakia, Thailand, and USA) could be listed. Overall, wide variations in CBCT features and technical specifications were identified.

CONCLUSIONS

CBCT in dentomaxillofacial radiology is a generic term applicable to a broad range of CBCT machines and features. Experimental outcomes and literature statements regarding radiation doses, imaging performance and diagnostic applicability of dental CBCT cannot be simply transferred from one CBCT model to another considering a wide variation in technical characteristics and clinical diagnostic performance. The information tabulated in the present study will be later provided on the International Association of DentoMaxilloFacial Radiology website (www.iadmfr.one).

The way we were (and how we got here): fifty years of technology changes in dental and maxillofacial radiology

The history of the last 50 years (1970-2020) of technological changes and progresses for equipment and procedures in dental and maxillofacial radiology is related from the insider perspective of an industrial physicist and technologist who has been instrumental at innovating and developing medical equipment in different parts of the world. The onset and improvement of all major categories of dental and maxillofacial radiographic equipment is presented, from the standpoint of their practical acceptance and impact among common dentists and maxillofacial radiologists: X-ray sources and detectors for intraoral radiography, and panoramic systems, both film-based and digital (including photo-stimulated phosphor plates); and cone beam CT.

Detection and analysis of enamel cracks by ICG-NIR fluorescence dental imaging

Cracked teeth are the third most common cause of tooth loss, but there is no reliable imaging tool for the diagnosis of cracks. Here, we demonstrate the feasibility of indocyanine green near-infrared fluorescence (ICG-NIRF) dental imaging for the detection of enamel cracks and enamel-dentin cracks in vitro in the first (ICG-NIRF-I, 700-950 nm) and second (ICG-NIRF-II, 950-1700 nm) imaging windows with transmission excitation light, and compared ICG-NIRF with conventional NIR illumination-II (NIRi-II) and X-ray imaging. Dentin cracks were detected by CT scan, while most enamel cracks, undetectable under X-ray imaging, were clearly visible in NIR images. We found that ICG-NIRF-II detected cracks more effectively than NIRi-II, and that light orientation is an important factor for crack detection: an angled exposure obtained better image contrast of cracks than parallel exposure, as it created a shadow under the crack. Crack depth could be evaluated from the crack shadow in ICG-NIRF and NIRi-II images; from this shadow we could determine crack depth and discriminate enamel-dentin cracks from craze lines. Cracks could be observed clearly from ICG-NIRF images with 1-min ICG tooth immersion, although longer ICG immersion produced images with greater contrast. Overall, our data show that ICG-NIRF dental imaging is a useful tool for diagnosing cracked teeth at an early stage.

Mandibular molar C-shaped root canals in 5th millennium BC China

OBJECTIVE

The aim of this study was to analyze the occurrence and variations in C-shaped canals in ancient Chinese teeth and compare the differences of these features between ancient and age-matched modern populations.

DESIGN

Approximately 5000-year-old craniofacial bone remains were collected from the fossils of 38 individuals (total: 68 mandibular second molars) excavated from the Jiaojia site. The control group comprised of an equal number of randomly selected modern samples. We used cone-beam computed tomography to scan the mandible along the apex-crown axis and analyzed the canal morphology, based on Fan's categorization criterion, at 2 mm, 5 mm, and 8 mm to the apical level. Grooves on the lingual and buccal sides were also recorded.

RESULTS

The proportion of C-shaped roots among ancient samples on the left and right sides were 48.57 % (17/35 teeth) and 54.55 % (18/33 teeth), respectively, and 51.47 % (35/68 teeth) in the total sample. Conversely, in the control group, 44.12 % (15/34) and 38.24 % (13/34) occurred on the left and right sides, respectively, and 41.18 % (28/68) in the total sample. Among the C-shaped canals from the Jiaojia site samples, the classification type changed between two adjacent levels in 84.31 % of samples. Approximately 35 (51.5 %) teeth had a fused root, 20 (29.41 %) had one shallow buccal and one deep lingual groove. The occurrence of C-shape variation was not significantly correlated with time (p＞0.05).

CONCLUSIONS

This study identified a high rate of C-shaped root canals among individuals of Jiaojia who lived approximately 5000 years ago.

Quantitative analysis of metal artifact reduction using the auto-edge counting method in cone-beam computed tomography

The metal artifact reduction (MAR) algorithm is used in most CBCT unit to reduce artifact from various dental materials. The performance of MAR program of a CBCT unit according to the dental material type under different imaging mode was evaluated as introducing automatic quantification of the amount of artifact reduced. Four customized phantoms with different dental prostheses (amalgam, gold, porcelain-fused-metal, zirconia) underwent CBCT scanning with and without the MAR option. The imaging was performed under varied scanning conditions; 0.2 and 0.3 mm³ voxel sizes; 70 and 100 kVp. The amount of artifacts reduced by each prosthesis and scanning mode automatically counted using canny edge detection in MATLAB, and statistical analysis was performed. The overall artifact reduction ratio was ranged from 17.3% to 55.4%. The artifact caused by the gold crown was most effectively reduced compared to the other prostheses (p < 0.05, Welch’s ANOVA analysis). MAR showed higher performance in smaller voxel size mode for all prostheses (p < 0.05, independent t-test). Automatic quantification efficiently evaluated MAR performance in CBCT image. The impact of MAR was different according to the prostheses type and imaging mode, suggesting that thoughtful consideration is required when selecting the imaging mode of CBCT.

Cone-beam computed tomography and its applications in dental and maxillofacial radiology

Cone-beam computed tomography (CBCT) was first used in dental and maxillofacial radiology (DMFR) at the end of the 1990s. Since then, it has been successfully established as the standard three-dimensional radiographic imaging technique in DMFR, with a wide variety of applications in this field. This manuscript briefly reviews the background information on the technology and summarises available data on effective dose and dose optimisation. In addition, typical clinical applications and indications of the technique in DMFR are presented.

Orthodontic-surgical treatment for a patient with Class II malocclusion and inadequate maxillary incisor inclination

Dental health and patient satisfaction at the end of orthodontic treatment are needed if the treatment is to be considered successful. This case report highlights the importance of proper diagnosis for a patient initially treated with camouflage, despite the indications for surgery. A 16-year-old male patient sought treatment complaining about his appearance. He had been using an appliance for 6 years without improvement. He had a convex profile, an enlarged lower third of the face, reduced cervical-mandibular line, and Class II molar relationship. The maxillary incisors had excessive buccal root torque, throbbing pain, and dental mobility, with no visible bone coverage in the tomographic sections. The cephalometric analysis confirmed the skeletal Class II relationship (ANB, 11.6°; Wits appraisal, 14.2 mm) because of severe mandibular deficiency (SNB, 71.2°), aggravated by the vertical growth tendency (FMA, 27.3°). Changes in IMPA (108.1°) and U1-NA (0.9°; -2.9 mm) reflected the previous orthodontic attempt to compensate for the malocclusion. After periodontal and endodontic evaluation, a new treatment plan was developed. The incisors would be positioned in their bone bases, the mandibular first premolars would be extracted to create space for the second molars and increase the overjet, and the patient would be referred for orthognathic surgery. The patient was satisfied with the esthetic and functional results of this treatment.

The Effects of Distribution of Image Matched Fiducial Markers on Accuracy of Computer-Guided Implant Surgery

PURPOSE

Image registration of the optical intraoral scan to computed tomography image is essential for computer-guided implant surgery. The remaining teeth, which are considered to be congruent structures observed in the scan and radiographic images, are used to perform the image registration. The purpose of this study was to evaluate the effects of the distribution of matching fiducial points on the accuracy of the image registration.

MATERIALS AND METHODS

A partially edentulous model with three anterior remaining teeth was prepared. Two mini dental implants were inserted in the posterior edentulous areas on both sides, and computed tomography and surface scan data were obtained. Three groups were set according to the distribution of the image matching points used: localized distribution, unilateral distribution, and bilateral distribution. Fifteen graduate students performed the registration process in each group using the same image matching method. The accuracy of image registration was evaluated by measuring the geometric discrepancies between the radiographic and registered scan images in the anterior, middle, and posterior regions. One-way and two-way analysis of variance with the Tukey HSD post hoc test were used for statistical analysis (α = 0.05) RESULTS: In general, the registration discrepancy was lowest in the bilateral distribution group, followed by the unilateral distribution and localized distribution groups (p< 0.001). In the regional analysis, the registration error tended to increase as the measurement region moved farther from the matching points. The distribution of the matching points and measurement regions had a statistical interaction in the accuracy of image registration.

CONCLUSION

The accuracy of image registration of the surface scan to the computed tomography is affected by the matching point distribution that can be improved by placing artificial markers in the edentulous areas.

Long-term clinical performance of flapless implant surgery compared to the conventional approach with flap elevation: A systematic review and meta-analysis

BACKGROUND

The conventional implant approach involves flap elevation, which may result in increased soft tissue and bone loss and postoperative morbidity. The flapless surgical technique, aided by three-dimensional medical imaging equipment, is regarded as a possible alternative to the conventional approach to alleviate the above issues. Several studies have been performed regarding the role of flapless implant surgery. However, the results are inconsistent and there is no robust synthesis of long-term evidence to better inform surgeons regarding which type of surgical technique is more beneficial to the long-term prognosis of patients in need of implant insertion.

AIM

To compare the long-term clinical performance after flapless implant surgery to that after the conventional approach with flap elevation.

METHODS

PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and grey literature databases were searched from inception to 23 September 2019. Randomised controlled trials (RCTs) and cohort studies comparing the long-term clinical performance after flapless implant surgery to that after the conventional approach over a follow-up of three years or more were included. Meta-analyses were conducted to estimate the odds ratios (ORs) or mean differences (MDs) and their 95% confidence intervals (CIs) between the long-term implant survival rate, marginal bone loss, and complication rate of the flapless and conventional groups. Subgroup analyses were carried out to account for the possible effects of the guided or free-hand method during flapless surgery.

RESULTS

Ten articles, including four RCTs and six cohort studies, satisfied the eligibility criteria and nine of them were included in the meta-analysis. There was no significant difference between the long-term implant survival rate [OR = 1.30, 95%CI (0.37, 4.54), P = 0.68], marginal bone loss [MD = 0.01, 95%CI (-0.42, 0.44), P = 0.97], and complication rate [OR = 1.44, 95%CI (0.77, 2.68), P = 0.25] after flapless implant surgery and the conventional approach. Moreover, subgroup analyses revealed that there was no statistically significant difference between the implant survival rate [guided: OR = 1.52, 95%CI (0.19, 12.35), P = 0.70]; free-hand: n = 1, could not be estimated), marginal bone loss [guided: MD = 0.22, 95%CI (-0.14, 0.59), P = 0.23; free-hand: MD = -0.27, 95%CI (-1.10, 0.57), P = 0.53], or complication rate [guided: OR = 1.16, 95%CI (0.52, 2.63), P = 0.71; free-hand: OR = 1.75, 95%CI (0.66, 4.63), P = 0.26] in the flapless and conventional groups either with use of the surgical guide or by the free-hand method.

CONCLUSION

The flapless surgery and conventional approach had comparable clinical performance over three years or more. The guided or free-hand technique does not significantly affect the long-term outcomes of flapless surgery.

Mandibular cortical indices and their relation to gender and age in the cone-beam computed tomography

OBJECTIVES

The purpose of this study is to evaluate normal ranges of cortical bone Hounsfield units indices through cone beam CT images, and to investigate their relationships with age and sex.

METHODS

700 adult human cone beam CT images were evaluated retrospectively, and divided into 4 age groups. Six different cortical bone Hounsfield unit measurements were applied bilaterally, where gender and age were recorded. Collected data were subjected to statistical analysis and ANOVA tests were used for various comparisons.

RESULTS

The cortical bone measurements between female and male patients were significantly different (p<0.05). Cortical bone thickness indices showed greater values in male patients compare to female patients (p<0.05). Quantitative mandibular indices were significantly lower in first age group (18-30 years) than other three older age groups (p<0.01).

CONCLUSION

The results of this study seems to propose a persistent alteration in the mandibular cortical bone with age and that this influced by sex. Further studies with larger patient groups are needed to clarify and understand these mandibular indices.

Sinus floor elevation or referral for further diagnosis and therapy: A comparison of maxillary sinus assessment by ENT specialists and dentists using cone beam computed tomography

OBJECTIVES

To compare ear, nose, and throat (ENT) specialists and dentists assessing health or pathology of maxillary sinuses using cone beam computed tomography (CBCT).

MATERIAL AND METHODS

Two ENT specialists and two oral surgeons assessed 100 CBCT datasets of healthy patients referred for dental implant placement in the posterior maxilla and decided on the possibility of sinus floor elevation or the necessity for further diagnostic examinations based solely on radiographic findings. Inter-rater agreements within the same specialty were calculated with Cohen's kappa and overall agreements with Fleiss kappa, and factors influencing the decisions taken were evaluated using regression analyses.

RESULTS

The correlation between all four raters was generally fair to moderate. The intra-specialty comparison showed a lower correlation between dentists than between ENT specialists. Absence of membrane thickening and total or subtotal sinus opacification showed the highest predictive value for a consensus in favor of sinus floor elevation and ENT referral, respectively. Flat membrane thickening with an irregular surface morphology was associated with disagreement between the examiners. Dome-shaped membrane thickenings were often considered as to be referred by dentists but not by ENTs.

CONCLUSION

The assessment of maxillary sinuses using CBCT imaging exhibited unsatisfactory agreement between ENT specialists and oral surgeons. Referral guidelines based on accidental CBCT findings that aim to diagnose relevant sinus pathologies early and avoid unnecessary diagnostics and/or therapies are needed, and an initial proposal for such recommendations is provided. Further research on correct interpretation of sinus findings and a validation of the present recommendations are required.

Quantification of DNA Double Strand Breaks and Oxidation Response in Children and Adults Undergoing Dental CBCT Scan

Assessing the possible biological effects of exposure to low doses of ionizing radiation (IR) is one of the prime challenges in radiation protection, especially in medical imaging. Today, radiobiological data on cone beam CT (CBCT) related biological effects are scarce. In children and adults, the induction of DNA double strand breaks (DSBs) in buccal mucosa cells and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) and antioxidant capacity in saliva samples after CBCT examination were examined. No DNA DSBs induction was observed in children nor adults. In children only, an increase in 8-oxo-dG levels was observed 30 minutes after CBCT. At the same time an increase in antioxidant capacity was observed in children, whereas a decrease was observed in adults. Our data indicate that children and adults react differently to IR doses associated with CBCT. Fully understanding these differences could lead to an optimal use of CBCT in different age categories as well as improved radiation protection guidelines.

Effect of Diagnosis by Two-Dimensional Radiography Versus CBCT on Surgical Aspects of Transmigrated Impacted Mandibular Canines

Purpose

The transmigration of mandibular canines is a rare clinical finding. The present study aimed to compare the effect of diagnosis by two-dimensional radiography and cone beam computed tomography on surgical aspects of transmigrated impacted mandibular canines.

Patients and Methods

A total of 20 patients (mean age 20.18 ± 3.36 years; male/female = 1.5:1), reporting to the Department of Oral and Maxillofacial Surgery with transmigrated impacted mandibular canines and planned for surgical removal, were randomly divided into two groups of ten patients each. Group A patients were diagnosed using 2D radiographs (orthopantomograms and occlusal view radiographs), and Group B patients were diagnosed using CBCT scans. The effects of the diagnosis on surgical aspects were compared in both the groups using various intraoperative and post-operative parameters.

Results

The operating surgeons experienced lesser operating time and more accuracy in terms of prediction of surgical approach in Group B patients than in Group A. Post-operative complications, including post-operative vitality of the adjacent tooth and lower lip paraesthesia, were seen to be more in Group A patients than in Group B.

Conclusion

Increased precision in localization of transmigrated impacted mandibular canines was seen by using CBCT, leading to better surgical experience and lesser post-operative complications.

Geometric analysis of alveolar bone around the incisors after anterior retraction following premolar extraction

OBJECTIVE

To evaluate changes in shape and alterations in thickness and vertical marginal bone levels of the alveolar bone around the maxillary and mandibular incisors before and after orthodontic treatment with premolar extraction using geometric morphometric analysis.

MATERIALS AND METHODS

Thirty-six patients with Class I bialveolar protrusion who underwent orthodontic treatment with premolar extraction were included. Cone-beam computed tomographic scans were obtained from the patients before and after treatment. Five fixed landmarks and 70 semilandmarks were used to represent the morphology of the alveolar bone around the maxillary and mandibular incisors. The coordinates of the landmarks of the alveolar bones were generated by Procrustes fit. The labial and lingual alveolar bone thicknesses around the maxillary and mandibular incisors and vertical marginal bone level were assessed quantitatively.

RESULTS

There was a significant difference in shape change of the alveolar bone before and after treatment. The deformation grid of the thin plate spline showed that the thickness and vertical marginal bone decreased on the lingual side after treatment. Shape changes were greater for the lingual alveolar bone on the mandibular incisor than for the maxillary incisors.

CONCLUSIONS

Orthodontic treatment with premolar extraction might cause loss of alveolar bone around the maxillary and mandibular incisors. Careful consideration is needed to avoid iatrogenic degeneration of periodontal support around the incisors, particularly in the lingual area.

Guided implant surgery risks and their prevention

Ideal implant placement may reduce surgical complications, such as nerve injury and lingual cortical plate perforation, and minimize the likelihood of functional and prosthetic compromises. Guided implant surgery (GIS) has been used as the means to achieve ideal implant placement. GIS refers to the process of digital planning, custom-guide fabrication, and implant placement using the custom guide and an implant system-specific guided surgery kit. GIS includes numerous additional steps beyond the initial prosthetic diagnosis, treatment planning, and fabrication of surgical guide. Substantial errors can occur at each of these individual steps and can accumulate, significantly impacting the final accuracy of the process with potentially disastrous deviations from proper implant placement. Pertinent overall strategies to reduce or eliminate these risks can be summarized as follows: complete understanding of the possible risks is fundamental; knowledge of the systems and tools used is essential; consistent verification of both diagnostic and surgical procedures after each step is crucial; proper training and surgical experience are critical. This review article summarizes information on the accuracy and efficacy of GIS, provides insight on the potential risks and problems associated with each procedural step, and offers clinically relevant recommendations to minimize or eliminate these risks.

Cone beam CT for perioperative imaging in hearing preservation Cochlear implantation - a human cadaveric study

Background

Knowledge of the cochlear implant array’s precise position is important because of the correlation between electrode position and speech understanding. Several groups have provided recent image processing evidence to determine scalar translocation, angular insertion depth, and cochlear duct length (CDL); all of which are being used for patient-specific programming. Cone beam computed tomography (CBCT) is increasingly used in otology due to its superior resolution and low radiation dose. Our objectives are as followed:

Validate CBCT by measuring cochlear metrics, including basal turn diameter (A-value) and lateral wall cochlear duct length at different angular intervals and comparing it against microcomputed CT (uCT).

Explore the relationship between measured lateral wall cochlear duct length at different angular intervals and insertion depth among 3 different length electrodes using CBCT.

Methods

The study was performed using fixed human cadaveric temporal bones in a tertiary academic centre. Ten temporal bones were subjected to the standard facial recess approach for cochlear implantation and imaged by CBCT followed by uCT. Measurements were performed on a three-dimensional reconstructed model of the cochlea. Sequential insertion of 3 electrodes (Med-El Flex24, 28 and Soft) was then performed in 5 bones and reimaged by CBCT. Statistical analysis was performed using Pearson’s correlation.

Results

There was good agreement between CBCT and uCT for cochlear metrics, validating the precision of CBCT against the current gold standard uCT in imaging. The A-value recorded by both modalities showed a high degree of linear correlation and did not differ by more than 0.23 mm in absolute values. For the measurement of lateral wall CDL at various points along the cochlea, there was a good correlation between both modalities at 360 deg and 720 deg (r = 0.85, p < 0.01 and r = 0.79, p < 0.01). The Flex24 electrode displayed consistent insertion depth across different bones.

Conclusions

CBCT reliably performs cochlear metrics and measures electrode insertion depth. The low radiation dose, fast acquisition time, diminished metallic artifacts and portability of CBCT make it a valid option for imaging in cochlear implant surgery.

Comparison of in situ cone beam computed tomography scan data with ex vivo optical scan data in the measurement of root surface area

OBJECTIVE

The aim of this study was to compare root surface area (RSA) measurements of single-root teeth in a sheep mandible based on cone beam computed tomography (CBCT) with measurements made with an optical scanner.

STUDY DESIGN

Eight anterior teeth of a sheep cadaver mandible were scanned in situ by using CBCT with 3 different exposure parameters, followed by treatment with smoothing software. The teeth were then extracted and scanned individually with an optical scanner. Three-dimensional digital models of the teeth were reconstructed on the basis of CBCT and optical scanner data. RSA data were calculated, and an equivalence test was used to statistically compare the measurements with significance of difference established at α = 0.05.

RESULTS

The means of the differences between RSA measurements from CBCT and optical scanning ranged from 0.33% to 3.01%. There were no statistically significant differences between the 2 methods. The smoothing parameters for good fitness of the linear regression were determined to be 0.8 for the smooth factor, 8 for iterations, and 0 for compensate shrinkage.

CONCLUSIONS

The proposed CBCT technique to measure RSA is feasible. RSA data obtained from CBCT in situ are as accurate as optical scanner measurements ex vivo.

Surgically-oriented anatomical study of mandibular premolars: A CBCT study

Background

The knowledge of root canal anatomy and of the anatomical relationship should be considered mandatory when planning surgical endodontics. The aim of the study was to investigate the anatomical features of mandibular premolars, evaluating their relationship with mental nerve.

Material and Methods

CBCT scans were evaluated recording the number of roots, root canal configuration and the relationship with mental nerve of 100 mandibular premolars. After simulating a resection of 3 mm of the root, the shape and the number of canals, and the distance to the buccal and lingual bone plate and to the mental foramen was evaluated.

Results

The one root - one canal configuration was the most common configuration. The mental foramen was located at the level of MSPs in 40% cases, and it was between MSP and MFP in 46% of cases. The distance between the apex and the vestibular plate was lower than the distance to the lingual one.

Conclusions

We found a significant heterogeneity in the anatomy of mandibular premolars. CBCT could be considered important when planning surgical endodontics in this region. Key words:Cone-Beam Computed Tomography, bicuspid, root canal, root canal therapy, apicoectomy, mandibular nerve.

kVp, mA, and voxel size effect on 3D voxel-based superimposition

OBJECTIVES

To evaluate the effect of changing kVp, mA, and voxel size on the accuracy of voxel-based superimposition on the anterior cranial base.

MATERIALS AND METHODS

Cone beam computed tomography (CBCT) scans were taken on a phantom skull using different kVp, mA, and voxel size combinations. CBCT scans were superimposed using commercially available software. Two separate open-source software programs were used to generate a three-dimensional (3D) color map objective assessment of the differences in seven different regions: Nasion, Point A, Zygomatic (right and left), Point B, and Gonial (right and left). Each region had around 200 points that were used to calculate the mean differences between the superimpositions.

RESULTS

Intraclass correlation showed excellent reliability (0.95). Lowering the kVp made the biggest difference, showing an average discrepancy of 0.7 ± 0.3 mm, and a high mean of 1.4 ± 0.3 in the Right Gonial region. Lowering the mA showed less of a discrepancy, with an average of 0.373 ± 0.2 mm, and the highest discrepancy, also on the Right Gonial Area, of 0.7 ± 0.1 mm. The voxel size had the least impact on the accuracy of registered volumes, with mean discrepancy values of less than 0.2 mm.

CONCLUSIONS

Using different CBCT settings can affect the accuracy of the voxel-based superimposition method. This is particularly the case when using low kVp values, while changes in mA or voxel sizes did not significantly interfere with the superimposition outcome.

Is the maxillary sinus volume affected by concha bullosa, nasal septal deviation, and impacted teeth? A CBCT study

PURPOSE

Various mechanisms play an important role in the growth of maxillary sinus cavities. The purpose of this study was to investigate the correlations of maxillary sinus volume (MSV) with nasal septal deviation (NSD), concha bullosa (CB) and impacted teeth using cone-beam computed tomography (CBCT) images.

METHODS

From 55 patients, a total of 110 maxillary sinus images were obtained and examined. Data including age, gender, impacted third molar, canine teeth, NSD, and CB were examined. MSV was measured using the MIMICS software (Materialise HQ Technologielaan, Leuven, Belgium). All statistical analyses were performed using the SPSS (Statistical Package for Social Sciences, version 21) software and p values < 0.05 were considered to indicate statistical significance.

RESULTS

Mean volume of the right maxillary sinus was 13.566 cm³, while the left was 13.882 cm³. The rate of patients with right and left impacted third molar teeth was 49.1% and 47.3%, respectively. The rate of right and left impacted canines was 1.8% and 5.5%, respectively. NSD was found in 56.4% of CBCT examinations and right and left CB were observed in 30.9% and 32.7% of the patients' examinations, respectively. Males had a significantly higher mean sinus volume than females for both sides (p < 0.05). There were no significant correlations between MSV and age (p > 0.05). No significant differences were found between MSV and impacted teeth, NSD and CB (p > 0.05).

CONCLUSION

NSD, CB, impacted teeth, and age were not found to be related to MSV. Gender had an effect on MSV and males had higher mean sinus volume than females.

IAEA survey of dental cone beam computed tomography practice and related patient exposure in nine Central and Eastern European countries

OBJECTIVES

Cone beam CT (CBCT) in dentistry and maxillofacial surgery is a widely used imaging method for the assessment of various maxillofacial and dental pathological conditions. The objective of this study was to summarize the results of a multinational retrospective-prospective study that focused on patient exposure in this modality.

METHODS

The study included 27 CBCT units and 325 adult and paediatric patients, in total. Data on patients, clinical indications, technical parameters of exposure, patient dose indicator, or, alternatively, dose to phantom were collected. The dose indicator used was air kerma-area product, P_KA.

RESULTS

In most scanners operators are offered with a variety of options regarding technical parameters, especially the field of view size. The median and the third quartile value of P_KA for adult patients in 14 different facilities were 820 mGy cm² and 1000 mGy cm² (interquartile range = 1058 mGy cm²), and 653 mGy cm² and 740 mGy cm² (interquartile range = 1179 mGy cm²) for children, as reported by four different institutions. Phantom dose data were reported from 15 institutions, and median P_KA ranged from 125 mGy cm² to 1951 mGy cm². Median P_KA values varied by more than a 10-fold between institutions, mainly due to differences in imaging protocol used, in particular field of view and tube current-exposure time product.

CONCLUSIONS

The results emphasize the need for a cautious approach to using dental CBCT. Imaging only when the clinical indications are clear, accompanied with the appropriate radiographic techniques and the optimum imaging protocol, will help reduce radiation dose to patients.

Cone-Beam Computed Tomography in Orthodontics

Unlike patients receiving implants or endodontic treatment, most orthodontic patients are children who are particularly sensitive to ionizing radiation. Cone-beam computed tomography (CBCT) carries risks and benefits in orthodontics. The principal risks and limitations include ionizing radiation, the presence of artifacts, higher cost, limited accessibility, and the need for additional training. However, this imaging modality has several recognized indications in orthodontics, such as the assessment of impacted and ectopic teeth, assessment of pharyngeal airway, assessment of mini-implant sites, evaluation of craniofacial abnormalities, evaluation of sinus anatomy or pathology, evaluation of root resorption, evaluation of the cortical bone plate, and orthognathic surgery planning and evaluation. CBCT is particularly justified when it brings a benefit to the patient or changes the outcome of the treatment when compared with conventional imaging techniques. Therefore, CBCT should be considered for clinical orthodontics for selected patients. Prescription of CBCT requires judicious and sound clinical judgment. The central question of this narrative review article is: when does CBCT add value to the practice of orthodontics? To answer this question, this article presents discussion on radiation dosage of CBCT and other imaging techniques used in orthodontics, limitations of CBCT in orthodontics, justifying the use of CBCT in orthodontics, and the benefits and evidence-based indications of CBCT in orthodontics. This review summarizes the central themes and topics in the literature regarding CBCT in orthodontics and presents ten orthodontic cases in which CBCT proved to be valuable.

Method validation to assess in vivo cellular and subcellular changes in buccal mucosa cells and saliva following CBCT examinations

OBJECTIVES

Cone-beam CT (CBCT) is a medical imaging technique used in dental medicine. However, there are no conclusive data available indicating that exposure to X-ray doses used by CBCT are harmless. We aim, for the first time, to characterize the potential age-dependent cellular and subcellular effects related to exposure to CBCT imaging. Current objective is to describe and validate the protocol for characterization of cellular and subcellular changes after diagnostic CBCT.

METHODS

Development and validation of a dedicated two-part protocol: 1) assessing DNA double strand breaks (DSBs) in buccal mucosal (BM) cells and 2) oxidative stress measurements in saliva samples. BM cells and saliva samples are collected prior to and 0.5 h after CBCT examination. BM cells are also collected 24 h after CBCT examination. DNA DSBs are monitored in BM cells via immunocytochemical staining for γH2AX and 53BP1. 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) and total antioxidant capacity are measured in saliva to assess oxidative damage.

RESULTS

Validation experiments show that sufficient BM cells are collected (97.1 ± 1.4 %) and that γH2AX/53BP1 foci can be detected before and after CBCT examination. Collection and analysis of saliva samples, either sham exposed or exposed to IR, show that changes in 8-oxo-dG and total antioxidant capacity can be detected in saliva samples after CBCT examination.

CONCLUSION

The DIMITRA Research Group presents a two-part protocol to analyze potential age-related biological differences following CBCT examinations. This protocol was validated for collecting BM cells and saliva and for analyzing these samples for DNA DSBs and oxidative stress markers, respectively.

Torque application helps to diagnose incomplete syndesmotic injuries using weight-bearing computed tomography images

OBJECTIVE

Accurate identification of distal tibio-fibular syndesmotic injuries is essential to limit potential deleterious post-traumatic effects. To date, conventional radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) have shown limited utilization. This cadaver study evaluates the utility of weight-bearing CT scans on the assessment of incomplete and more complete syndesmotic injuries.

MATERIALS AND METHODS

Ten male cadavers (tibial plateau to toe-tip) were included. Weight-bearing CTs were taken under four test conditions, with and without torque on the tibia (corresponding to external rotation of the foot and ankle). First, intact ankles (native) underwent imaging. Second, the anterior-inferior tibio-fibular ligament (AITFL) was transected (condition 1). Then, the deltoid ligament (condition 2) was transected, followed by the interosseous membrane (IOM, condition 3). Finally, the posterior-inferior tibio-fibular ligament (PITFL) was transected (condition 4). The medial clear space (MCS), the tibio-fibular clear space (TFCS), and the tibio-fibular overlap (TFO) were assessed on digitally reconstructed radiographs (DRRs), and on axial CT images.

RESULTS

The TFO differentiated isolated AITFL transection from native ankles when torque was applied. Also under torque conditions, the MCS was a useful predictor of an additional deltoid ligament transection, whereas the TFCS identified cadavers in which the PITFL was also transected.

CONCLUSION

Torque application helps to diagnose incomplete syndesmotic injuries when using weight-bearing CT. The TFO may be useful for identifying incomplete syndesmotic injuries, whereas the MCS and TFCS predict more complete injuries.

Linear measurements of sinus floor elevation based on voxel-based superimposition of cone beam computed tomography images

BACKGROUND

Postsurgical evaluation of sinus floor elevation regularly involves linear measurements of the elevated volumes in the cone beam computed tomography (CBCT) images. The accuracy of measurements could be compromised due to ill-defined sinus floor outline if implants are placed simultaneously.

PURPOSE

The aim was to examine a CBCT superimposition method to improve the measurement accuracy.

MATERIALS AND METHODS

Twenty patients who received transalveolar sinus floor elevation with immediate implantation were enrolled. CBCTs before and after surgery were transformed into digital imaging and communications in medicine format and imported into the Dolphin Imaging software. Voxel-based superimposition was automated to merge the files. In the superimposed image, parameters including alveolar bone height, protruded implant length, and total elevated height were measured. The superimposition and measurements were performed independently by two examiners and in two timepoints with 1-week time interval. We used intraclass correlation coefficient (ICC) to analyze the interexaminer and intraexaminer agreements.

RESULTS

Of measured parameters, the mean of difference between two timepoints ranged from 0.18 to 0.26 mm by examiner 1, and from 0.16 to 0.20 mm by examiner 2. ICCs were equal or greater than 0.98, indicating perfect intraexaminer agreement. For interexaminer reliability, the largest mean of difference was 0.27 mm in measuring alveolar bone height between two examiners. ICCs were greater than 0.98, showing perfect interexaminer agreement.

CONCLUSIONS

The voxel-based superimposition of pre- and post-surgical CBCT images with Dolphin Imaging is an effective and reliable way for linear measurements so as to assess the surgical outcome. There is minimal effect on reproducibility of measured data by different timepoints or performers.

Comparison of cone-beam computed tomography and panoramic imaging in assessing the relationship between posterior maxillary tooth roots and the maxillary sinus: A systematic review

The objective of the present systematic review was to analyze research articles that compare the accuracy of panoramic imaging to cone-beam computed tomography (CBCT) in assessing the relationship between posterior maxillary tooth roots and the maxillary sinus. A comprehensive literature search was conducted using various databases. Initial searching yielded 64 results, and after exclusion, five full-text articles were eligible. All were cohort studies, and the CBCT and panoramic images were either obtained from a pre-existing database or patients were recruited specifically for the study. Analysis showed that a panoramic image is sufficient for accurately detecting when the roots are at distinct distance from the sinus. However, if the roots are either laterally or medially projecting over the sinus and "just touching" it, panoramic images generally misinterpret this position, and instead make the root appear to be in the sinus. There were mixed results for when the root tip penetrates the sinus. Some studies claimed there was high agreeance between both modalities in this situation, while others had a low level of agreeance. In these situations, ordering a CBCT should be strongly considered to properly assess oral surgery risk with regard to maxillary posterior teeth.

Comparison of cone-beam computed tomography and panoramic radiography in the evaluation of maxillary sinus pathology related to maxillary posterior teeth: Do apical lesions increase the risk of maxillary sinus pathology?

Purpose

The aims of this study were first, to compare panoramic radiography with cone-beam computed tomography (CBCT) for evaluating topographic relationships, such as the classification of maxillary posterior teeth and their distance to the maxillary sinus floor; and second, to determine the relationship between maxillary sinus pathology and the presence of apical lesions.

Materials and Methods

In total, 285 paired CBCT and panoramic radiography records of patients (570 maxillary sinuses) were retrospectively analyzed. Both imaging modalities were used to determine the topographic relationship of the maxillary posterior teeth to the sinus floor. Mucosal thickening >2 mm was considered a pathological state. Data were analyzed using the chi-square, Wilcoxon, and Mann-Whitney U tests. Odds ratios (ORs) and confidence intervals (CIs) were calculated.

Results

The closest vertical distance measurements made between posterior maxillary teeth roots and the maxillary sinus on panoramic radiography and CBCT scans showed statistically significant differences from each other (P<0.05). Compared to panoramic radiography, CBCT showed higher mean values for the distance between the maxillary sinus floor and maxillary posterior teeth roots. The CBCT images showed that at least 1 apical lesion adjacent to the right maxillary sinus increased the risk of maxillary sinus pathology by 2.37 times (OR, 2.37; 95% CI, 1.58-3.55, P<0.05).

Conclusion

Panoramic radiography might lead to unreliable diagnoses when evaluating the distance between the sinus floor and posterior roots of the maxillary teeth. Periapical lesions anatomically associated with maxillary sinuses were a risk factor for sinus mucosal thickening.

Computer-Guided Dental Implant Treatment of Complete Arch Restoration of Edentulous and Terminal Dentition Patients

The treatment of completely edentulous or soon-to-be completely edentulous dental arches with complete-arch fixed denture restorations, supported by dental implants, are some of the more complicated patient cases in oral and maxillofacial surgery and prosthodontics. This article discusses the use of digital technologies, computerized tomographic (CT) guided planning software applications, and surgical guides in treating these complex dental implant patient cases. A discussion of the nuances and workflows of different types of treatments are provided. The importance of experience and a multi-disciplinary team approach is emphasized.

Accuracy of cone beam computed tomography in measuring thicknesses of hard-tissue-mimicking material adjacent to different implant thread surfaces

Background/purpose

To evaluate the measurement accuracy of hard-tissue thicknesses adjacent to dental implants with different thread designs on images obtained from cone beam computed tomography (CBCT) using an in vitro model.

Materials and methods

On 4 × 13-mm implant, the neck of the implant was designed with micro-threads, and the apical part was covered by macro-threads; these implants were placed in a vinyl polysiloxane block that mimicked hard-tissue. Models were prepared with various thicknesses of 2.0, 1.0, 0.5 and 0.3 mm adjacent to the dental implant. Each model was scanned using CBCT, and the thickness of the cortical bone from the outer surface of the micro-threads and macro-threads were recorded. Ground sections were prepared, and the thickness was measured with electronic calipers as the gold standard (GS) measurement.

Results

CBCT measurements of the micro-thread surface were consistently underestimated compared to the GS measurement when the thickness of the hard-tissue-mimicking material was ≤1.0 mm. In comparison, CBCT measurements of the macro-thread surface closely approximated the standard measurement, except when the thickness of the hard-tissue-mimicking material was 0.3 mm. The mean percentage errors from the standard measurement for the 2.0-, 1.0-, 0.5-, and 0.3-mm thickness groups were 4.8%, 16.4%, 37.8%, and 92.6%, respectively, for the micro-thread group, and were 0.6%, 2.9%, 9.5%, and 40.8%, respectively, for the macro-thread group.

Conclusion

Within the limitations of this study, we conclude that CBCT may not produce sufficient resolution for thin sections of hard tissue-mimicking materials adjacent to micro-thread surfaces.

Outcome of orthodontic treatment in subjects with periodontal disease. Part III: a CBCT study of external apical root resorption

Background

No evidence is present on the risk for external apical root resorption (EARR) during orthodontic treatment (OT) of adult patients with periodontal disease.

Aim

To examine EARR after OT in subjects with periodontal disease and to analyse how intrusion and change in inclination of the most proclined maxillary incisors influence EARR.

Methods

The study included 50 patients with periodontal disease. Sub-gingival debridement by ultrasonic instrumentation supplemented with hand instruments was performed by experienced dental hygienist after baseline examination for all patients. For the control group, final periodontal treatment (PT) was performed before orthodontic tooth movement. For the test group patients, final PT was performed after levelling and alignment phases were finished, before the active space closure with elastic chain and/or inter-arch elastic traction for sagittal correction was started. OT was performed with a straight-wire appliance. Micro-implants or implants were used for posterior anchorage. Cone beam computed tomography examinations were performed before and after OT. EARR of all single-rooted teeth were measured. EARR of the most proclined maxillary incisor was related to intrusion and change in inclination angle.

Results

EARR after OT was observed in median 80.7 per cent (interquartile range 22.02) of single-rooted teeth [mean 1.2 (standard deviation 0.44) mm]. In 82.3 per cent of teeth, EARR was 2 mm or less. Severe EARR was found in 8 per cent of patients and five maxillary incisors (less than 1 per cent of all teeth). The amount of intrusion and change in inclination angle of the most proclined maxillary central incisor influenced the extent of EARR. Mean EARR was significantly higher when OT lasted more than 18 months (P = 0.02).

Conclusions

OT in conjunction with PT in periodontal patients resulted in EARR in 81 per cent of all single-rooted teeth. Intrusion and change in inclination angle of the most proclined maxillary central incisor influenced the extent of EARR, as did longer OT.

Three-dimensional assessment of external apical root resorption after maxillary posterior teeth intrusion with miniscrews in anterior open bite patients

OBJECTIVE

The objective of this study was to assess the external apical root resorption (EARR) of the maxillary posterior teeth after intrusion with miniscrews.

METHODS

Fifteen patients (13 females and 2 males) with age ranging from 14.5 to 22 years (mean 18.1 ±2.03 years) were selected to participate in this study. All patients presented with anterior open bite of 3 mm or more. An intrusion force of 300 g was applied on each side to intrude the maxillary posterior teeth. Cone beam computed tomography (CBCT) scans were taken pretreatment and post-intrusion and were analyzed to evaluate the EARR.

RESULTS

The maxillary posterior teeth were intruded in average 2.79 ± 0.46 mm (p< 0.001) in 5.1 ± 1.3 months, and all examined roots showed statistically significant EARR (p< 0.05) with an average of 0.55 mm, except the distobuccal root of the left first permanent molars and both the palatal and buccal roots of left first premolars, which showed no statistically significant changes.

CONCLUSIONS

The evaluated teeth presented statistically significant EARR, but clinically, due to the small magnitude, it was not considered significant. Moreover, the CBCT provided a good visualization of all roots in all three planes, and it was effective in detecting minimal degrees of EARR.

An Evaluation of Bone Mineral Density Using Cone Beam Computed Tomography in Patients with Ectodermal Dysplasia: A Retrospective Study at a Single Center in Turkey

BACKGROUND The aim of this retrospective study was to compare the measurements of bone mineral density (BMD) combined with volumetric dental tomography measurements taken from three main regions selected on the lower mandible, the right mandibular, medial mandibular, and left mandibular regions, in patients with ectodermal dysplasia and age-matched and gender-matched controls. Measurement of BMD in Hounsfield units (HUs) were evaluated using three-dimensional (3D) cone beam computed tomography (CBCT) imaging. MATERIAL AND METHODS Mandibular bone tomography images were evaluated from 9 women and 5 men diagnosed with ectodermal dysplasia and a control group of 9 women and 5 men. The HU values obtained according to age and gender of the total 28 study participants were measured. Statistical analysis of the data used Student's t-test. RESULTS BMD in the ectodermal dysplasia group was significantly lower compared with the BMD in the control group. Comparison of the left and right mandibular angulus regions showed that the BMD of patients with ectodermal dysplasia was significantly lower when compared with the control group in both regions, but no significant difference was found between the two groups in the BMD of the central mandibular region. CBCT was found to be an effective method for the measurement of BMD. CONCLUSIONS In patients with ectodermal dysplasia, reduced BMD should be taken into consideration when planning surgical interventions involving bone tissue and when planning implant surgery. The results of this study may be of value in dentistry and other fields of medicine.

Novel low-dose protocols using cone beam computed tomography in dental medicine: a review focusing on indications, limitations, and future possibilities

OBJECTIVES

A narrative review on the potential use of low-dose protocols for cone beam computed tomography (CBCT) was conducted to identify indications and their relevance for various dental disciplines.

MATERIALS AND METHODS

Google Scholar was searched using the words "low-dose CBCT". Reviews, consensus papers, clinical studies, and experimental studies were eligible for the initial screening process, but for data extraction only original articles were selected. Similar search procedures were then performed with the additional search words "pedo," "ortho," "endo," "implant," "perio," and "oral surgery." Furthermore, references of included articles were examined to identify further relevant articles.

RESULTS

After screening, 27 publications remained for the data extraction process. Low-dose protocols have been reported for specialties such as pediatric dentistry (evaluating orofacial clefts, periapical lesions, impacted teeth, and autotransplantation), orthodontics (cephalometric analysis and interim assessment of treatment results), endodontics (detecting root fractures, resorptions and periapical bone loss), implant dentistry (planning implant insertion, evaluating peri-implant fenestration and dehiscence), periodontology (assessing periodontal structures), and oral and maxillofacial surgery (assessing mandibular third molars and TMJs). Nevertheless, most of the literature available is related to non-clinical studies. Furthermore, there is a lack of position statements or guidelines from authoritative bodies regarding the use of low-dose protocols in dental medicine.

CONCLUSIONS

Low-dose protocols for CBCT imaging seem to have potential in various disciplines in dental medicine ranging from pediatric dentistry to oral and maxillofacial surgery. Dose reduction is usually achieved by mAs reduction, use of partial rotations, reduced number of projections, and larger voxel sizes, but seldom by kV reduction.

CLINICAL RELEVANCE

Albeit low-dose protocols have potential to result in a reduction of dose exposure for 3D imaging due to dental indications, there is a need to more clearly specify indications and limitations to avoid indiscriminate use of standard and high-dose CBCT scans in the future on the lines of ALARA/ALADA principles.

Cone Beam Computed Tomography-Based Anatomical Assessment of the Olfactory Fossa

This study aimed to investigate the olfactory fossa according to the Keros classification using cone beam computed tomography. This cross-sectional study analysed cone beam computed tomography images selected from a database belonging to a radiology centre. The scans of 174 healthy patients were analysed by using the Xoran software. Gender, age, and side were correlated with the Keros classification. The mean age of the 174 patients was 45.3 years. The most prevalent Keros classification was type II (65.52%), followed by type III (20.69%) and type I (13.79%). No significant differences were found between Keros classification and the variables age, right side (p value = 0.4620), and left side (p value = 0.5709). There were also no significant differences between gender and the variables right side (p value = 0.1421) and left side (p value = 0.2136). Based on these results, we suggest that cone beam computed tomography can be recommended for analysis of the anterior skull base. Keros type II was the most prevalent type in our sample.

What are the risk factors for maxillary sinus pathologies? A CBCT study

OBJECTIVE

Some anatomic variations may interfere with proper airflow in the maxillary sinus and predispose to maxillary sinus pathologies. It was also reported that as a result of the transport of microorganisms from infected periapical tissues, maxillary sinus pathologies can develop. The objective of this study was to determine the potential relationships of maxillary sinus septa, concha bullosa, nasal septal deviation, and teeth with periapical lesion to maxillary sinus pathologies.

METHODS

200 cone beam computed tomography scans obtained at Necmettin Erbakan University, Faculty of Dentistry from 2013 to 2018 were retrospectively reviewed for the presence of maxillary sinus septa, concha bullosa, nasal septal deviation, teeth with periapical lesions, and maxillary sinus pathologies. When maxillary sinus mucosal thickening exceeded 2 mm, it was considered as a pathological condition. Logistic regression analysis was used to determine the risk factors for maxillary sinus pathologies. p < 0.05 considered statistically significant.

RESULTS

185 (46.2%) of the 400 maxillary sinuses showed maxillary sinus pathologies. Maxillary sinus septa, concha bullosa, and nasal septal deviation were not found to be as a risk factor for the maxillary sinus pathologies (p > 0.05). At least one apical lesion adjacent to the maxillary sinus increased the maxillary sinus pathology by 5.24 times on the right (OR 5.24, p < 0.001) and by 4.67 times on the left side (OR 4.67, p < 0.001).

CONCLUSION

To prevent maxillary sinus pathologies, it is important for the teeth adjacent to the maxillary sinus to be healthy.

Comparison of upper airway measurement by lateral cephalogram in upright position and CBCT in supine position

Background/Purpose

Obstructive sleep apnea syndrome (OSAS) is a common form of sleep disorder. Lateral cephalograms and cone-beam computed tomography (CBCT) have been used for evaluation. However, it is lack of position comparison for these two assessments. Therefore, this study was aimed to evaluate the difference of upper airway measurements taken from lateral cephalograms in upright position and CBCT in supine position.

Material and methods

This retrospective study enrolled patients with lateral cephalograms and CBCT images due to diagnostic necessity. The anterior-posterior distance of most constricted area in pharynx (PASmin) and the distance from mandibular plane to hyoid bone (MP-H) were identified and measured from 21 normal subjects without obstructive sleep apnea (9 males and 12 females, mean age 21.2 years). A paired data were measured from lateral cephalograms taken in upright position and lateral cephalometric images derived from CBCT taken in supine position. Both images were taken within two months. All data were analyzed statistically.

Results

No significant difference was identified in intra-examiner reliability (P > 0.05). PASmin measured from lateral cephalograms in upright position was larger than that taken from CBCT derived cephalometric images, but without statistical significant difference (P = 0.073). Significant difference of MP-H length was identified between two different image taking methods (P = 0.000), and the measurement was significantly larger in cephalograms taken from upright position. No correlations were found among the variables (Body Mass Index (BMI), age, gender) in this study. The only two variables correlated were PASmin and MP-H, and they were negatively correlated (r = −0.535).

Conclusion

The anterior-posterior distance of most constricted area in pharynx (PASmin) and distance of mandibular plane to hyoid bone (MP-H) can be influenced due to change of body position.