Evaluation of the Correlation Between the Structural Parameters of Trabecular Bone in CBCT and the Primary Stability of Dental Implants

PURPOSE

To investigate the relationship between the structural parameters of trabecular bone obtained from CBCT imaging and the primary stability of dental implants.

MATERIALS AND METHODS

Sixty patients underwent implant placement followed by primary stability evaluation via measurement of the insertion torque (IT) and the implant stability quotient (ISQ). Gray values (GV) and the fractal dimension (FD) were also measured using pretreatment CBCT images.

RESULTS

FD values showed a positive and significant relationship with ISQ and IT values (P = .017 and P = .004, respectively). Additionally, there was a positive and significant correlation between GV and IT (P = .004) as well as between GV and ISQ (P = .010). FD and GV showed a considerable difference between the maxillary and mandibular jaws and were higher in the mandible. Only FD was significantly different between men and women and was higher in men. In the two age groups (older and younger than 45 years), only GV was considerably higher in people older than 45 (P < .05).

CONCLUSIONS

Both fractal dimension and gray values obtained from CBCT are efficient methods for predicting the primary stability of the implant due to their relationship with ISQ and IT values.

Electronic equipment and appliances in special wards of hospitals as a source of azole-resistant Aspergillus fumigatus: a multi-centre study from Iran

BACKGROUND

Azole-resistant Aspergillus fumigatus (ARAf), reported as a global public health concern, has been unexpectedly observed in different countries.

AIM

To identify ARAf and detect azole resistance related to the CYP51A mutation in different hospital environmental samples.

METHODS

In this multi-centre study from Iran, surfaces of electronic equipment and appliances from different hospitals in Iran were sampled using cotton swabs. All samples were cultured using azole-containing agar plates (ACAPs). Recovered Aspergillus isolates were identified at the species level using partial DNA sequencing of the β-tubulin gene. The azole susceptibility testing of A. fumigatus isolates was performed using the Clinical and Laboratory Standards Institute M38-A3 guideline. The sequencing of the CYP51A gene was also performed to detect mutations related to resistance.

FINDINGS

Out of the 693 collected samples, 89 (12.8%) Aspergillus species were recovered from ACAPs. Aspergillus fumigatus (41.6%) was the most prevalent, followed by A. tubingensis (23.6%) and A. niger (15.6%). Among 37 isolates of A. fumigatus, 19 (51.3%) showed high minimum inhibitory concentration (MIC) values to at least one of the three azoles, voriconazole, itraconazole, and posaconazole. CYP51A polymorphisms were detected in all 19 isolates, of which 52.6% showed the TR34/L98H mutation. Other detected mutations were G432C, G448S, G54E/G138C, F46Y, and Y121F/M220I/D255E. T289F and G432C were the first reported mutations in ARAf.

CONCLUSION

There was a considerable level of azole resistance in hospital environmental samples, a serious warning for patients vulnerable to aspergillosis. Our findings have also revealed a different mutation pattern in the CYP51A gene.

Association of root morphology of mandibular second molars on panoramic-like and axial views of cone-beam computed tomography

BACKGROUND

Knowledge about the anatomy and morphology of the root canal system is essential for successful surgical and non-surgical root canal treatments. However, precise assessment of the root morphology and anatomy is not often possible on two-dimensional radiographs. This study aimed to investigate the association of root morphology of mandibular second molars on panoramic-like and axial views of cone-beam computed tomography (CBCT).

METHODS

This cross-sectional study evaluated 1,231 CBCT scans of mandibular second molars obtained between October 2018 and February 2022 that were retrieved from the archives of a private radiology clinic. Panoramic-like images were reconstructed from the CBCT scans. The root morphology of mandibular second molars was classified on panoramic-like images as type 1, 2, 3, 4, or 5. The root pattern on axial CBCT images was classified into three types of single, double and C-shaped. The association of root morphology on panoramic-like and axial CBCT views was analyzed by the Chi-square test and Fisher's exact test at 0.05 level of significance.

RESULTS

Of all, 62.7% of mandibular second molars were type 1; out of which, 97.3% had a double-root pattern on axial CBCT images. Also, 28.6% of them were type 2; of which, 92.6% had a double-root pattern. Moreover, 3.9% were type 3; of which, 47.9% had a C-shaped pattern; 0.9% were type 4, and 45.5% of them showed a single-root pattern; 3.8% were type 5 with 76.6% of them showing a single-root pattern. The prevalence of C-shaped canals was higher in females, and most C-shaped canals had a C3 pattern.

CONCLUSION

Root morphology on panoramic-like CBCT views had a strong association with the root canal pattern on axial CBCT views. According to the results, mandibular second molars with a type 3 morphology on panoramic-like CBCT images are highly probable to have a C-shaped canal.

Prevalence of bifid variations of the mandibular canal in an Iranian population using cone-beam computed tomography

OBJECTIVES

Bifid mandibular canal (MC) is an anatomical variation of the MC. This study aimed to assess the prevalence and shape of bifid MC in an Iranian population.

MATERIALS AND METHODS

A total of 681 patients who had undergone cone-beam computed tomography (CBCT) for different purposes between 2018 and 2020 were evaluated. After detection, bifid MCs were classified into four types forward, buccolingual, dental, and retromolar. CBCT images were assessed by two oral and maxillofacial radiologists. Data were analyzed by SPSS using an independent t-test and Chi-square test.

RESULTS

Bifid MC was found in 23 (3.4%) out of 681 patients, with a mean age of 32.21 years. Ten patients (1.5%) had a bifid MC on the right side, 6 (0.9%) on the left side, and 7 (1%) bilaterally. However, no significant correlation was found between laterality and the prevalence of bifid MC (P > 0.05). Bifid MC was found in 8 males (34.8%) and 15 females (65.2%). Gender had no significant correlation with the prevalence of bifid MC (P > 0.05). Forward type was the most common (n = 8, 1.2%) followed by buccolingual (n = 5, 0.73%), dental (n = 2, 0.3%), and retromolar (n = 1, 0.14%) types.

CONCLUSION

According to the present results, bifid MC was not uncommon in the Iranian population of the present study, and forward type was the most common, followed by buccal and then dental bifid MCs. There was no significant correlation between sex and age with bifid MC but bifid MC was detected more frequently in females than males, and it was seen unilaterally in a higher percentage of the cases.

Cone-beam computed tomography assessment of the root canal morphology of primary molars

BACKGROUND

This study aimed to assess the root canal morphology of primary molars using cone-beam computed tomography (CBCT).

METHODS

This cross-sectional study evaluated 60 maxillary and mandibular primary first and second molars on CBCT scans of patients retrieved from the archives of Hamadan School of Dentistry between 2018-2020. The teeth were evaluated regarding the number of roots and canals, canal type according to the Vertucci's classification, and root surface concavities. Data were analyzed descriptively and by independent t-test.

RESULTS

The most frequent number of canals and roots in the maxillary right and left first molars was 3 canals (60%) and 3 roots (80%). These values were 4 canals (80%) and 5 canals (50%) with 3 roots in the maxillary right and left second molars, respectively, 4 canals (100%) and 2 roots (50%), and 3 canals (60%) and 2 roots (50%) in mandibular right and left first molars, respectively, and 4 canals (92.3%) and 3 roots (61.5%) in mandibular right and left second molars. Vertucci's type IV was the most common canal type in mesial and distal canals, type I was the most common in mesiobuccal, mesiolingual, distobuccal, and distolingual, and types I and II were the most common in the palatal canal. The maximum and minimum concavities were noted in the buccal (26.7%) and mesial (8.3%) surfaces, respectively.

CONCLUSIONS

A wide variation exists in the number of roots and canals of maxillary and mandibular primary molars, which calls for further attention in treatment of such teeth.

Effect of different intracanal posts and exposure parameters on detection of vertical root fractures by cone-beam computed tomography

This study evaluated the effect of different amperage values and voxel sizes of two CBCT scanners on VRF detection in the presence of different intracanal posts. After post-space preparation, VRFs were induced in half of the samples of 20 maxillary premolars. Five different intracanal posts were passively placed in each root canal. Samples were scanned using CS 9300 and Cranex3D with two different voxel sizes and amperage setting in each unit. The diagnostic sensitivity, specificity and accuracy were compared using the Mann-Whitney and Kruskal-Wallis tests (α = 0.05). Changes in amperage and voxel size did not affect the detection of VRFs (p ⟩ 0.05). The VRF detection accuracy was the highest in fibreglass and the lowest in nickel-chromium group. Changes in amperage and voxel size within assessed values do not seem to influence the detection of VRF whereas different intracanal post-materials have significant effect on VRF detection.

Effect of photobiomodulation therapy with different wavelengths on bone mineral density in osteoporotic rats

Osteoporosis is associated with severe pain, bone deformity, fracture, and bone loss. It is important to find strategies to prevent bone resorption and treat osteoporosis. This study sought to assess the effect of photobiomodulation therapy (PBMT) with different wavelengths on bone mineral density (BMD) in osteoporotic rats. This animal study evaluated 63 adult female rats. The rats underwent ovariectomy to induce osteoporosis. Ovariectomized rats were randomly divided into 9 groups of control (OC), treatment with zoledronic acid alone (0.02 mg/kg), and treatment with 660 nm, 810 nm, and 940 nm PBMT alone (3 times a week for 6 weeks, energy density of 4 J/cm2), and combined with zoledronic acid. The healthy control group (HC) only underwent sham surgery. The rats underwent cone-beam computed tomography (CBCT) 52 days after the first treatment session to measure their BMD according to the gray value (GV) of images. To assess the biomechanical properties of bone, the resected bones were subjected to 3-point bending test (3-PBT). The experimental groups had significant differences with the OC group regarding radiographic and biomechanical properties of bone (P < 0.05), indicating a healing course. No significant difference was noted between the experimental groups treated with different laser wavelengths and those treated with zoledronic acid (P > 0.05). In the condition of this study, it was found that PBMT at a constant energy density of 4 J/cm2 with 660-, 810-, and 940-nm wavelengths is effective for enhancement of bone mineral density and biomechanical properties. No significant difference was noted between different wavelengths of diode laser regarding radiographic and biomechanical properties of bone.

Comparison of Diagnostic Quality of Multidetector Computed Tomography and Cone-Beam Computed Tomography in High and Low Resolution Modes for Assessment of the Nasal Cavity

Background

We aimed to compare the diagnostic quality of multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) in high (HR) and low (LR) resolution modes for assessment of the nasal cavity and paranasal sinuses.

Methods

This in vitro study was conducted on 5 dry human skulls by using a CBCT and a MDCT scanner in HR and LR modes to assess their diagnostic quality for 21 anatomical landmarks of the nose. The quality of images was evaluated by two oral and maxillofacial radiologists and a dentist using a four-point Likert scale of (I) poor, (II) decreased, (III) good, and (IV) excellent. Data were analyzed by STATA at 95% confidence interval. The Chi-square test was applied to compare the quality of visualization of landmarks based on the type of scanner.

Results

The diagnostic quality of HR CBCT and CT for the majority of landmarks was higher than that of LR CBCT and CT (P<0.05). The diagnostic quality of HR CBCT for agger nasi cells (P=0.010), olfactory cleft (P=0.032), sphenoethmoidal recess (P=0.032), and nasolacrimal duct (P=0.014) and LR CBCT for the middle turbinate (P=0.046) and middle meatus (P=0.031) was significantly higher than that of MDCT.

Conclusion

The diagnostic quality of HR CBCT and CT for the majority of the landmarks in the nasal cavity and paranasal sinuses was higher than that of LR CBCT and CT. For the majority of landmarks, the diagnostic quality of CBCT and CT was the same; while for some landmarks, the diagnostic quality of HR and LR CBCT was higher than HR and LR CT. In general, CBCT has high efficacy for evaluation of the paranasal sinuses and the nasal cavity, and provides diagnostic information comparable to those provided by CT, but with a much lower radiation dose.

Comparison of the amount of artifacts induced by zirconium and titanium implants in cone-beam computed tomography images

Background

This study aimed to compare the amount of artifacts induced by the titanium and zirconium implants on cone-beam computed tomography (CBCT) and assess the effect of different exposure settings on the image quality for both materials.

Methods

In this experimental study, 30 zirconium and 30 titanium implants were placed in bovine rib bone blocks. CBCT images were taken in two different fields of view (FOV: 4 × 6 cm² and 6 × 8 cm²) and at two resolutions (133 µ and 200 µ voxel size). Subsequently, two observers assessed the images and detected the amount of artifacts around the implants through gray values. Data were analyzed by paired t test and independent t test using SPSS 21 and the 0.05 significance level.

Results

The results showed that titanium implants caused lower amounts of artifacts than zirconium implants, which was statistically significant (P < 0.001). The larger FOV (6 × 8 cm²) resulted in a lower amount of artifacts in both groups, although the results were only statistically significant in the zirconium group (P < 0.001). The amount of artifacts was increased when using the 133 µ voxel size in both groups, which was only significant in the zirconium group (P < 0.001).

Conclusion

Our results suggest that zirconium implants induce higher amounts of artifacts than titanium ones. We also concluded that the artifacts could be minimized using the larger FOV and voxel size.

3D-printed bi-layered polymer/hydrogel construct for interfacial tissue regeneration in a canine model

OBJECTIVES

There are complications in applying regenerative strategies at the interface of hard and soft tissues due to the limited designs of constructs that can accommodate different cell types in different sites. The problem originates from the challenges in the adhesion of dissimilar materials, such as polymers and hydrogels, that can be suitable for regenerating different tissues such as bone and soft tissues. This paper presents a design of a new hybrid construct in which a polymer (polycaprolactone (PCL)) membrane firmly adheres to a layer of hydrogen (gelatin).

METHODS

PCL membranes with defined size and porosity were fabricated using 3D printing. The gelatin layer was attached to the PCL membranes using the aminolysis procedure. We have examined this construct for the application of Guided Bone Regeneration (GBR) as a typical surgical regenerative procedure of the oral cavity at the interface of bone and soft tissue. Complete in vitro and in vivo investigations on canine tibia bone defects have been performed. Histological analyses for fibrosis morphometric and bone morphometric evaluation, as well as bone-fibrosis histological grading and CBCT imaging, were conducted.

RESULTS

Chemical and morphological studies of the membrane proved that gelatin was uniformly attached to the aminolyzed PCL membranes. The in vitro and in vivo studies indicated the membrane's biocompatibility, mechanical stability, and barrier function for the GBR application. Furthermore, in vitro study showed that the membranes could improve osteogenesis and the regeneration of bone defects. The results illustrated that the mean bone density in the membrane groups was about three times more than that of the control group.

SIGNIFICANCE

The fabricated 3D-printed hybrid Gelatin/PCL bi-layered membrane can be a good candidate for interfacial tissue engineering and a promising membrane for GBR procedure.

Complementarity of surgical therapy, photobiomodulation, A-PRF and L-PRF for management of medication-related osteonecrosis of the jaw (MRONJ): an animal study

Background

This study aimed to evaluate the complementarity of surgical therapy, photobiomodulation (PBM), advanced platelet-rich fibrin (A-PRF), and Leukocyte and platelet-rich fibrin (L-PRF) for the management of medication-related osteonecrosis of the jaw (MRONJ).

Methods

Sixty rats underwent injection of zoledronate followed by left mandibular first and second molar extractions to induce MRONJ lesions. All rats were examined for the signs of MRONJ 8 weeks post-dental extraction. Forty-nine rats with positive signs of MRONJ were appointed to seven different groups as follows: control (Ctrl); surgery alone (Surg); surgery and PBM (Surg + PBM); surgery and A-PRF insertion (Surg + APRF); surgery and L-PRF insertion (Surg + LPRF); surgery, A-PRF insertion, and PBM (Surg + APRF + PBM); surgery, L-PRF insertion, and PBM (Surg + LPRF + PBM). Euthanasia was carried out 30 days after the last treatment session. The lesions' healing was evaluated clinically, histologically, and radiographically. Data were analyzed using STATA software version 14, and the statistical significance level was set at 5% for all cases.

Results

According to the present study, A-PRF and L-PRF treatment resulted in significant improvements in clinical, histological, and radiographical parameters compared to the Ctrl group (P < 0.05). The PBM also decreased wound dimensions and the number of empty lacunae compared to the Ctrl group (P < 0.05). Surg + APRF + PBM and Surg + LPRF + PBM were the only groups that presented a significantly higher mean number of osteocytes (P < 0.05). No significant differences were observed between A-PRF and L-PRF treatment groups (P > 0.05).

Conclusions

Surgical resection followed by applying A-PRF or L-PRF reinforced by PBM showed optimal wound healing and bone regeneration in MRONJ lesions.

In vivo efficacy of 3D-printed elastin-gelatin-hyaluronic acid scaffolds for regeneration of nasal septal cartilage defects

Nasal septal cartilage perforations occur due to the different pathologies. Limited healing ability of cartilage results in remaining defects and further complications. This study sought to assess the efficacy of elastin-gelatin-hyaluronic acid (EGH) scaffolds for regeneration of nasal septal cartilage defects in rabbits. Defects (4 × 7 mm) were created in the nasal septal cartilage of 24 New Zealand rabbits. They were randomly divided into four groups: Group 1 was the control group with no further intervention, Group 2 received EGH scaffolds implanted in the defects, Group 3 received EGH scaffolds seeded with autologous auricular chondrocytes implanted in the defects, and Group 4 received EGH scaffolds seeded with homologous auricular chondrocytes implanted in the defects. After a 4-month healing period, computed tomography (CT) and magnetic resonance imaging (MRI) scans were obtained from the nasal septal cartilage, followed by histological evaluations of new tissue formation. Maximum regeneration occurred in Group 2, according to CT, and Group 3, according to both T1 and T2 images with 7.68 ± 1.36, 5.44 ± 2.41, and 8.72 ± 3.02 mm2 defect area respectively after healing. The difference in the defect size was statistically significant after healing between the experimental groups. Group 3 showed significantly greater regeneration according to CT scans and T1 and T2 images. The neocartilage formed over the underlying old cartilage with no distinct margin in histological evaluation. The EGH scaffolds have the capability of regeneration of nasal cartilage defects and are able to integrate with the existing cartilage; yet, they present the best results when pre-seeded with autologous chondrocytes.

Assessment of the accuracy of laser-scanned models and 3-dimensional rendered cone-beam computed tomographic images compared to digital caliper measurements on plaster casts

Purpose

This study investigated the accuracy of laser-scanned models and 3-dimensional (3D) rendered cone-beam computed tomography (CBCT) compared to the gold standard (plaster casts) for linear measurements on dental arches.

Materials and Methods

CBCT scans and plaster models from 30 patients were retrieved. Plaster models were scanned by an Emerald laser scanner (Planmeca, Helsinki, Finland). Sixteen different measurements, encompassing the mesiodistal width of teeth and both arches' length and width, were calculated using various landmarks. Linear measurements were made on laser-scanned models using Autodesk Meshmixer software v. 3.0 (Autodesk, Mill Valley, CA, USA), on 3D-rendered CBCT models using OnDemand 3D v. 1.0 (Cybermed, Seoul, Korea) and on plaster casts by a digital caliper. Descriptive statistics, the paired t-test, and intra- and inter-class correlation coefficients were used to analyze the data.

Results

There were statistically significant differences between some measurements on plaster casts and laser-scanned or 3D-rendered CBCT models (P<0.05). Molar mesiodistal width and mandibular anterior arch width deviated significantly different from the gold standard in both methods. The largest mean differences of laser-scanned and 3D-rendered CBCT models compared to the gold standard were 0.12±0.23 mm and 0.42±0.53 mm, respectively. Most of the mean differences were not clinically significant. The intra- and inter-class correlation results were acceptable for all measurements (>0.830) and between observers (>0.801).

Conclusion

The 3D-rendered CBCT images and laser-scanned models were useful and accurate alternatives to conventional plaster models. They could be used for clinical purposes in orthodontics and prostheses.

Magnetic resonance imaging study of incidental findings in the paranasal sinuses and ostiomeatal complex

Purpose

This study aimed to assess incidental abnormal findings in the paranasal sinuses and anatomical variations of the ostiomeatal complex (OMC) on magnetic resonance imaging (MRI) scans.

Materials and Methods

MRI scans of 616 patients (mean age, 44.0±19.4 years) were evaluated. Prior to obtaining the MRI scans, a checklist of patients’ clinical symptoms was filled out after obtaining their consent. The Lund-Mackay classification was used to assess the paranasal sinuses and OMC. The prevalence of abnormal findings and their associations with patients’ age, sex, and subjective symptoms were analyzed by the chi-square test, independent-sample t-test, and analysis of variance. The level of significance was set at 0.05.

Results

Abnormal findings in the paranasal sinuses were detected in 32.0% of patients, with a significantly higher prevalence in males (P<0.05), but no significant association with age (P>0.05). Epithelial thickening and retention cyst were the most common abnormal findings in the paranasal sinuses. According to the Lund-Mackay classification, 93% of the study population had normal sinuses (score<4). Concha bullosa and paradoxical concha were detected in 15.3% and 3.4%, respectively, with no significant association with the presence of septal deviation or Lund-Mackay classification (P>0.05).

Conclusion

Considering the relatively high prevalence of abnormal findings in the paranasal sinuses, it appears that clinical symptoms alone are not sufficient to diagnose sinusitis. A more accurate strategy would be to assess radiographic images of the paranasal sinuses and use a classification system. Sinusitis should be suspected in patients receiving a high score in this classification.

Cone-beam computed tomographic analysis of apical transportation and centering ratio of ProTaper and XP-endo Shaper NiTi rotary systems in curved canals: an in vitro study

Background

Cleaning and shaping of the root canal system is an important step of endodontic treatment. Canal transportation is a common procedural error in preparation of curved canals. This study aimed to compare the canal transportation and centering ratio of two rotary files in curved canals using cone-beam computed tomography (CBCT).

Methods

Forty-four extracted human mandibular first molars with mature apices and 10° to 30° apical curvature were selected. The samples were randomly divided into two groups (n = 22) with similar curvature. The canals were prepared with ProTaper and XP-endo Shaper file systems according to the manufacturers’ instructions. The CBCT images were obtained using Cranex 3D CBCT scanner before and after root canal preparation, and canal transportation and centering ratio of the files at 3, 4 and 5 mm levels from the apex were calculated. Data were compared between the two groups using independent t-test at 0.05 level of significance.

Results

The ProTaper Universal caused greater canal transportation and had lower centering ratio than XP-endo Shaper in both mesiodistal and buccolingual directions at all levels from the apex. The difference between the two groups regarding canal transportation was significant at all levels from the apex in buccolingual direction (P < 0.05) except for 3 mm from the apex (P > 0.05). The difference between the two groups regarding centering ratio was not significant (P > 0.05) in mesiodistal direction at all levels except for 4 mm from the apex (P < 0.05).

Conclusion

The ProTaper Universal causes greater canal transportation in both buccolingual and mesiodistal directions than XP-endo Shaper.

Performance of Bioceramic-based Root Filling Material with Artifact Reduction Properties in the Detection of Vertical Root Fractures Using Cone-beam Computed Tomography

Introduction:

In Cone-beam Computed Tomography (CBCT) images, metallic artifacts by root filling materials reduce the quality of images. It seems that bioceramic sealers produce fewer artifacts than gutta-percha. In this situation, the possibility of VRF detection could increase, and therefore, flap and exploratory surgery would not be needed. The purpose of this study was to evaluate the performance of a bioceramic-based root filling material in the detection of Vertical Root Fractures (VRF) in CBCT imaging.

Materials and Methods:

This study was conducted at the dental school from March to August 2019, and 100 healthy human mandibular premolar teeth were obtained and randomly divided into two equal groups. The teeth were filled with either AH26 and gutta-percha or bioceramic root filling materials. VRF was induced on half of the decoronated teeth in each group using a Global Testing Machine, and the others were considered control. CBCT imaging was performed by the Cranex 3D machine. Comparisons of the 2 groups were made using the Mann-Whitney test.

Results:

There was a significant difference between the two groups of bioceramic and gutta-percha in the measured indices, including sensitivity (P=0.017), specificity (P=0.018), positive predictive value (P=0.018), negative predictive value (P=0.018), and accuracy (P=0.011). The Area Under Curve (AUC) also showed a significant difference between the two groups (P=0.011). According to Kappa test results, no significant difference was obtained between the findings of the two observers.

Conclusion:

Different root filling materials showed a different extent of artifact in CBCT images. Bioceramic root filling material induces fewer artifacts in CBCT images, and the diagnostic value of VRF in CBCT images in the root canals filled with it is greater than those filled with AH26 and gutta-percha.

Knowledge Level of Iranian Dental Practitioners Towards Digital Radiography And Cone-Beam Computed Tomography

Objective: This study aimed to assess the knowledge level of Iranian dental practitioners about digital radiography(DR) andcone-beamcomputedtomography (CBCT). Material and Methods: In this crosssectional study, a researcher-designed questionnaire was administered among 180 general dentists and specialists. The questionnaire had three main domains of demographic information, fifteen questions about knowledge of DR (advantages, disadvantages, physical properties) and twenty six questions about knowledge of CBCT (indications, applications, advantages, route of knowledge acquisition). Data were analyzed using descriptive statistics, t-test and Pearson’s correlation coefficient. Results: Of 180 participants, 76 (42.2%) were females. The minimum, maximum and mean± standard deviation scores obtained in DR were 4, 14, and 9.031 ± 1.85 and in CBCT were 0,26 and 18.56 ± 4.81, respectively. In the CBCT domain, the participants had maximum knowledge about “low radiation dose” (72.8%) and minimum knowledge about the “role of CBCT in determination of bone density” (45%). In DR domain, the participants had maximum knowledge about “no need for radiographic films” (75.6%) and minimum knowledge about “not requiring manual processing” (15.6%). Overall, participants had higher level of knowledge about CBCT than DR. An inverse correlation was noted between age and work experience with the number of correct answers. However, no significant difference was noted in the knowledge level of males and females regarding CBCT or DR (p = 0.233 and p = 0.227, respectively). Conclusions: further education seem imperative for dentists in this respect for more efficient diagnosis and treatment planning, minimize patient radiation dose and save time and cost.   Keywords Digital radiography; Cone-Beam computed tomography; Knowledge; Dentists.

Anatomical characteristics of mandibular bone in skeletal Class I, II and III patients by using cone beam computed tomography images in an iranian population

Objetive: This study aimed to compare the anatomical characteristics of the mandible in patients with skeletal class I, II and class III disorders using cone beam computed tomography (CBCT). Material and Methods: CBCT scans of patients between 17 to 40 years taken with NewTom 3G CBCT system with 12-inch field of view (FOV) were selected from the archive. Lateral cephalograms were obtained from CBCT scans of patients, and type of skeletal malocclusion was determined (Class I, II or III). All CBCT scans were evaluated in the sagittal, coronal and axial planes using the N.N.T viewer software. Results: The ramus height and distance from the mandibular foramen to the sigmoid notch in class II patients were significantly different from those in skeletal class I (P < 0.005). Distance from the mandibular canal to the anterior border of ramus in class III individuals was significantly different from that in skeletal class I individuals (P < .005). Conclusion: Length of the body of mandible in skeletal class I was significantly different from that in skeletal class II and III patients. Also, ramus height in skeletal class I was significantly different from that in skeletal class II patients. CBCT had high efficacy for accurate identification of anatomical landmarks.   Keywords Prognathism; Retrognathism; Mandible; Anatomy; Cone beam computed tomography.

Accuracy of maxillofacial prototypes fabricated by different 3-dimensional printing technologies using multi-slice and cone-beam computed tomography

Purpose

This study aimed to compare the accuracy of 3-dimensional (3D) printed models derived from multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) systems with different fields of view (FOVs).

Materials and Methods

Five human dry mandibles were used to assess the accuracy of reconstructions of anatomical landmarks, bone defects, and intra-socket dimensions by 3D printers. The measurements were made on dry mandibles using a digital caliper (gold standard). The mandibles then underwent MDCT imaging. In addition, CBCT images were obtained using Cranex 3D and NewTom 3G scanners with 2 different FOVs. The images were transferred to two 3D printers, and the digital light processing (DLP) and fused deposition modeling (FDM) techniques were used to fabricate the 3D models, respectively. The same measurements were also made on the fabricated prototypes. The values measured on the 3D models were compared with the actual values, and the differences were analyzed using the paired t-test.

Results

The landmarks measured on prototypes fabricated using the FDM and DLP techniques based on all 4 imaging systems showed differences from the gold standard. No significant differences were noted between the FDM and DLP techniques.

Conclusion

The 3D printers were reliable systems for maxillofacial reconstruction. In this study, scanners with smaller voxels had the highest precision, and the DLP printer showed higher accuracy in reconstructing the maxillofacial landmarks. It seemed that 3D reconstructions of the anterior region were overestimated, while the reconstructions of intra-socket dimensions and implant holes were slightly underestimated.

Sex determination by osteometric assessment of the mastoid process using Cone Beam Computed Tomography

Objective: Sex determination is one of the most important parameters to identify in forensic science. Because the mastoid process is the most resistant to damage due to its position in the skull base, it can be used for sex determination. The purpose of this study was to measure the dimensions and convexity and internal angles of the mastoid process to present a model of sex determination in Iranian population. Material and methods: This study was performed on three-dimensional images of 190 Cone Beam Computed Tomography (CBCT) of 105 women and 85 men. On each CBCT the distance between the porion and the mastoid (PM), mastoid length (ML), the distance between the mastoidale and the mastoid incision (M-I), the mastoid height (MH), the mastoid width (MW), intermastoidale distance (IMD) the lateral surfaces of the left and right mastoids (IMLSD) and the Mastoid medial convergence angle (MMCA) was measured on both the right and the left. The data were analyzed by descriptive statistics, t-test, and discriminant function analysis. Results: Significant differences were found for all variables except MMCA and MF in both sex. All measured variables except MW were greater for men than women. The discriminant model achieved a total accuracy of 93.7%. Among the measured factors IMD and IMSLD had the most influence on sex determination. Conclusion: Measuring the dimensions of the mastoid process is a very good method for sex determination with high accuracy of 90%. KEYWORDS Discriminant model; Cone beam computed tomography (CBCT); Sex determination; Mastoid process.

Comparison of data mining algorithms for sex determination based on mastoid process measurements using cone-beam computed tomography

Purpose

The mastoid region is ideal for studying sexual dimorphism due to its anatomical position at the base of the skull. This study aimed to determine sex in the Iranian population based on measurements of the mastoid process using different data mining algorithms.

Materials and Methods

This retrospective study was conducted on 190 3-dimensional cone-beam computed tomographic (CBCT) images of 105 women and 85 men between the ages of 18 and 70 years. On each CBCT scan, the following 9 landmarks were measured: the distance between the porion and the mastoidale; the mastoid length, height, and width; the distance between the mastoidale and the mastoid incision; the intermastoid distance (IMD); the distance between the lowest point of the mastoid triangle and the most prominent convex surface of the mastoid (MF); the distance between the most prominent convex mastoid point (IMSLD); and the intersecting angle drawn from the most prominent right and left mastoid point (MMCA). Several predictive models were constructed and their accuracy was compared using cross-validation.

Results

The results of the t-test revealed a statistically significant difference between the sexes in all variables except MF and MMCA. The random forest model, with an accuracy of 97.0%, had the best performance in predicting sex. The IMSLD and IMD made the largest contributions to predicting sex, while the MMCA variable had the least significant role.

Conclusion

These results show the possibility of developing an accurate tool using data mining algorithms for sex determination in the forensic framework.

Maxillary osteosarcoma: a case report and review of maxillary sinus space-occupying lesions

Osteosarcoma is a relatively rare lesion in the maxillary bone. The proximity of the lesion to the maxillary sinus provides a null space with the minimum resistance to progress prior to manifest clinically, which makes the early diagnosis more critical. We report a case of maxillary osteosarcoma in a 21-year old male patient who was presented with the chief complaint of the pain and swelling on the left side of palate since 2 months earlier. A cone-beam computed tomography of the maxilla revealed a diffuse hyper-intense entity at the left side of the maxilla. Totally-occupied maxillary sinus space, asymmetric periodontal ligament widening of the involved teeth and spiculated and sunray periosteal reaction were recognized. The diagnosis of osteosarcoma was established and confirmed by histopathology. This article reviews the sinus-occupying lesion in the following and describes the lesions originate within the maxillary sinus or arise from the adjacent odontogenic components. Keywords Case report; Maxillary sinus; Osteosarcoma.

Position of the hyoid bone and its correlation with airway dimensions in different classes of skeletal malocclusion using cone-beam computed tomography

Purpose

This study investigated the position of the hyoid bone and its relationship with airway dimensions in different skeletal malocclusion classes using cone-beam computed tomography (CBCT).

Materials and Methods

CBCT scans of 180 participants were categorized based on the A point-nasion-B point angle into class I, class II, and class III malocclusions. Eight linear and 2 angular hyoid parameters (H-C3, H-EB, H-PNS, H-Me, H-X, H-Y, H-[C3-Me], C3-Me, H-S-Ba, and H-N-S) were measured. A 3-dimensional airway model was designed to measure the minimum cross-sectional area, volume, and total and upper airway length. The mean cross-sectional area, morphology, and location of the airway were also evaluated. Data were analyzed using analysis of variance and the Pearson correlation test, with P values <0.05 indicating statistical significance.

Results

The mean airway volume differed significantly among the malocclusion classes (P<0.05). The smallest and largest volumes were noted in class II (2107.8±844.7 mm³) and class III (2826.6±2505.3 mm³), respectively. The means of most hyoid parameters (C3-Me, C3-H, H-Eb, H-Me, H-S-Ba, H-N-S, and H-PNS) differed significantly among the malocclusion classes. In all classes, H-Eb was correlated with the minimum cross-sectional area and airway morphology, and H-PNS was correlated with total airway length. A significant correlation was also noted between H-Y and total airway length in class II and III malocclusions and between H-Y and upper airway length in class I malocclusions.

Conclusion

The position of the hyoid bone was associated with airway dimensions and should be considered during orthognathic surgery due to the risk of airway obstruction.

Is Ultrasonography Efficient for the Detection of the Zygomatic Arch, Nasal Bone and Cartilage Fractures?

Background:

The high incidence of nasal and zygomatic arch fractures highlights the need for an accurate imaging modality for their detection. The superimposition of structures is a major problem in conventional radiography. Ultrasonography is a low-cost imaging modality with a wide range of applications, that does not employ ionizing radiation. This study aimed to assess the efficacy of ultrasonography for the detection of the zygomatic arch and nasal bone fractures.

Materials and Methods:

This study was conducted on 16 sheep heads. Artificial fractures were created in some parts of the zygomatic arch, dorsum and lateral wall of the nose, and nasal cartilage. All sheep heads underwent Cone-Beam Computed Tomography (CBCT) to ensure the presence of a fracture. Next, the lateral nasal and submentovertex radiographs were obtained, and ultrasonography was performed with a 12-15 MHz linear probe. Ultrasonography and radiography were repeated after 1 week to assess their reproducibility by calculating the kappa coefficient. Data were analyzed using Stata 11 software and Chi-square test.

Results:

The specificity and sensitivity of ultrasonography ranged from 87% to 100%, and 50% to 75%, respectively. The specificity and sensitivity of radiography ranged from 87% to 100%, and 62% to 87%, respectively. The differences between the two imaging modalities were not statistically significant (p>0.05). The kappa coefficient ranged from 46% to 100% for ultrasonography and 44% to 87% for radiography.

Conclusion:

Ultrasonography seemed useful for the detection of displaced bone and cartilage fractures. For non-displaced fractures, US is not recommended.

Evaluation of Sexual Dimorphism with Mandibular Parameters by Digital Panoramic Radiography

Introduction:

Sex determination is the first step of personal identification in the field of forensics and is essential for reconstructive profiling. The skull appears to be the most reliable part of the skeleton, apart from the pelvis, in sex determination. Tooth and bone are used as a key tool for personal identification due to their high resistance to decomposition and degradation. The present study aimed to evaluate the sexual dimorphism with mandibular parameters by digital panoramic radiography.

Materials and Methods:

In this analytical-descriptive study, the mandibular parameters in 315 females and 217 males, including the ramus height, the coronoid height, the mental height, the mandible body height, the minimum width of the ramus, the distance between the right and left gonial angle, the distance between the right and left condyle and the distance between the right and left coronoid, were measured in the panoramic radiography via SCANORA software. Discriminant function and canonical regression methods were used to determine the predictability of mandibular parameters in sexual dimorphism. P < 0.05 was considered to be statistically significant.

Results:

All parameters were statistically significant between genders (P<0.05). The mean of all parameters, except the gonial angle, in males, was higher than that of the female. Percentage of correctly classified in discriminant function based on the central and right side and left side dimorphic parameters of the mandible is 82.5% and 82.9%, respectively.

Conclusion:

According to the present study, panoramic radiography can be considered as a valuable tool in sex determination (with an accuracy of 82.5%), and all parameters of mandible had sexual dimorphism and showed that they are reliable parameters with a total accuracy of 82.5% in the sexual dimorphism.

Association of vitamin D, retinol and zinc deficiencies with stunting in toddlers: findings from a national study in Iran

OBJECTIVE

The objective of this study was to investigate the association of serum levels of 25(OH)D₃ (vitamin D), retinol (vitamin A) and zinc with stunting in a large sample of Iranian toddlers.

STUDY DESIGN

This was a cross-sectional study.

METHODS

A total of 4261 children, aged 10-36 months, who had Iranian birth certificates were included in the present study. Weight and height were measured by experienced professionals in accordance with standard protocols. Stunting was defined as a height-for-age z-score of <-1 standard deviation (SD) based on the World Health Organization (WHO) criteria (the WHO Child Growth Standards median). Serum levels of 25(OH)D₃, retinol and zinc were examined based on standard methods.

RESULTS

The mean age of the study participants was 19.2 ± 8.4 months. A significant inverse association was found between serum retinol concentrations and the odds of stunting such that after controlling for potential confounders, toddlers in the highest quartile of serum retinol levels had 29% lower odds of stunting than those in the lowest quartile (odds ratio [OR]: 0.71, 95% confidence interval [CI]: 0.53-0.97). Furthermore, a significant inverse association was found between serum levels of retinol and stunting in girls (OR: 0.57, 95% CI: 0.34-0.94), urban toddlers (OR: 0.66, 95% CI: 0.44-0.99) and those who did not use nutritional supplements (OR: 0.70, 95% CI: 0.52-0.95). Although serum 25(OH)D₃ levels were not significantly associated with stunting in the overall study population, we found a positive association among toddlers who used nutritional supplements. No significant association was found between serum levels of zinc and stunting.

CONCLUSION

We found a significant inverse association between serum levels of retinol and stunting in toddlers aged 10-36 months.

Evaluation of the effect of the inversion filter on enhancing the visibility of the mandibular incisive canal in comparison with the original images

BACKGROUND

The mandibular incisive canal (MIC) is a neural canal containing one of the lower branches of the inferior alveolar nerve, called the mandibular incisive nerve, which can get damaged and cause complications during the removal of bone from the interforaminal region.

OBJECTIVES

The aim of this study was to determine the effect of the inversion filter (IF) on improving the visibility of MIC as compared to the original images.

MATERIAL AND METHODS

In this retrospective, descriptive, analytical study, 343 samples of digital panoramic radiography were examined. The images were analyzed with and without IF. The frequency and confidence intervals (CIs) of identifying MIC were used to determine its visibility, both with IF and in the original images. Besides, the difference between the maximum and minimum diameters of the canal as well as the distance from MIC to the alveolar crest and to the mental foramen were examined. For statistical analysis, McNemar's test and the paired t-test were used, and the concordance was calculated using the kappa coefficient.

RESULTS

No significant differences were found in the prevalence of the incisive canal, or in its unilateral or bilateral visibility between the original and filtered radiography in this study (p = 0.42 and p = 0.67, respectively). The absolute values of the interval difference between MIC and the mental foramen, the maximum and minimum diameters of MIC, and the distance from MIC to the alveolar crest were statistically significant between the filtered and original radiography, although the difference was clinically unimportant.

CONCLUSIONS

The use of IF produced results similar to the original radiography; its application neither increased the clarity nor improved the visibility of the incisive canal.

Assessment of root canal morphology of maxillary and mandibular second molars in the Iranian population using CBCT

BACKGROUND

Inability to efficiently clean all root canals due to the complex anatomy of the root canal system is a common cause of endodontic treatment failure.

OBJECTIVES

This study aimed to assess the root canal morphology of the maxillary and mandibular second molars using cone-beam computed tomography (CBCT).

MATERIAL AND METHODS

This descriptive study evaluated 502 CBCT scans taken in the years 2014-2017. The number of roots and canals, type of canals according to the Vertucci classification, presence of maxillary second molars with 2 palatal roots, and C‑shaped canals in the maxillary and mandibular second molars were evaluated on CBCT scans separately by a radiologist and 2 endodontists. The data was analyzed using SPSS via descriptive statistics, Fisher's exact test, the independent samples t-test, and the χ2 test. All the analyses were performed with a confidence level of 95%.

RESULTS

The majority of the palatal, mesiobuccal and distobuccal roots of the maxillary second molars had 1 single canal of Vertucci type I; 21.5% of the mesiobuccal roots had a second mesiobuccal canal (p = 0.05).

CONCLUSIONS

Two-rooted mandibular second molars and 3-rooted maxillary second molars were the most common in our study population. Cone-beam computed tomography as a non-invasive and highly accurate imaging modality is efficacious for the detection of additional roots and C‑shaped canals.

Correlations between anatomical variations of the nasal cavity and ethmoidal sinuses on cone-beam computed tomography scans

Purpose

Anatomical variations of the external nasal wall are highly important, since they play a role in obstruction or drainage of the ostiomeatal complex and ventilation and can consequently elevate the risk of pathological sinus conditions. This study aimed to assess anatomical variations of the nasal cavity and ethmoidal sinuses and their correlations on cone-beam computed tomography (CBCT) scans.

Materials and Methods

This cross-sectional study evaluated CBCT scans of 250 patients, including 107 males and 143 females, to determine the prevalence of anatomical variations of the nasal cavity and ethmoidal sinuses. All images were taken using a New Tom 3G scanner. Data were analyzed using the chi-square test, Kruskal-Wallis test, and the Mann-Whitney test.

Results

The most common anatomical variations were found to be nasal septal deviation (90.4%), agger nasi air cell (53.6%), superior orbital cell (47.6%), pneumatized nasal septum (40%), and Onodi air cell (37.2%). Correlations were found between nasal septal deviation and the presence of a pneumatized nasal septum, nasal spur, and Haller cell. No significant associations were noted between the age or sex of patients and the presence of anatomical variations (P>0.05).

Conclusion

Radiologists and surgeons must pay close attention to the anatomical variations of the sinonasal region in the preoperative assessment to prevent perioperative complications.

Comparative Evaluation of Retreatability of Endodontically Treated Teeth using AH 26, Fluoride Varnish and Mineral Trioxide Aggregate-based Endodontic Sealers

Background and Objectives:

Endodontic sealers are used to fill the gap between the root filling material and canal walls. Retrievability is an important requirement for sealers and root filling materials in non-surgical endodontic retreatment. This study sought to assess the retreatability of fluoride varnish, AH 26 and Mineral Trioxide Aggregate (MTA)-based sealers using Cone-Beam Computed Tomography (CBCT).

Materials and Methods:

This in vitro, experimental study evaluated 45 extracted single-rooted, single-canal human mandibular premolars. Teeth with cracks or fracture were excluded. The root canals were prepared using ProTaper Universal rotary system up to size F4 according to the manufacturer’s instructions. The teeth were then randomly divided into three groups of 5% fluoride varnish, AH 26 and MTA Fillapex. CBCT scans were obtained of the teeth with 200 μm voxel size. MATLAB R2012 software was used to quantify the amount of sealer remaining in the canal. Two observers evaluated the images. Data were analyzed using SPSS via the Kruskal-Wallis and Mann Whitney tests.

Results:

The amount of sealer remaining in the root canals was significantly different among the three groups (P<0.05). The amount of AH 26 sealer remaining in the root canals (1.91±1.46) was significantly greater than MTA Fillapex (0.62±0.26) and fluoride varnish, but the latter two were not significantly different in this respect (P>0.05).

Conclusion:

Considering the adequate adhesion of fluoride varnish to dentin, its cariostatic effect and low cost, it seems to be a suitable alternative to the commonly used endodontic sealers.

Relationship of gray values in cone beam computed tomography and bone mineral density obtained by dual energy X-ray absorptiometry

OBJECTIVES

The aim of this study was to assess the correlation between bone mineral density (BMD) determined with cone beam computed tomography (CBCT) gray values and BMD determined by dual energy X-ray absorptiometry (DEXA).

STUDY DESIGN

Women age greater than 50 years requiring CBCT for implant treatment were included in the study. BMD was determined by calculating the mean gray value of CBCT cross-sectional images of anterior, premolar, retromolar, and tuberosity areas of the mandible and maxilla. Patients were then subjected to DEXA of the femoral neck and lumbar spine. Independent t tests, analysis of variance (ANOVA), Pearson's correlation tests, and receiver operating characteristic (ROC) evaluation were used for data analysis.

RESULTS

Of 61 asymptomatic patients (mean age 64 years), 47.5% and 55.7% had abnormal BMD, based on the T-scores of the femoral neck and lumbar spine, respectively. Significant correlations were noted between the T-scores of the femoral neck and lumbar spine and the gray values of the maxillary incisor and tuberosity areas.

CONCLUSIONS

A strong correlation exists between the CBCT gray values at different sites in the maxilla and the results of DEXA. A gray value less than 298 at the maxillary tuberosity can help distinguish patients with osteoporosis from normal individuals, with 66% to 67% accuracy and suggests the need for DEXA analysis.

Effect of exposure parameters of cone beam computed tomography on metal artifact reduction around the dental implants in various bone densities

Background

This study aimed to assess the effect of exposure parameters such as milliampere (mA) and field of view (FOV) of cone beam computed tomography (CBCT) on a metal artifact of dental implants placed in different bone densities.

Methods

A total of 27 bone blocks with different densities (nine were type 1, nine were types 2 and 3, and nine were type 4) were used in this in vitro, experimental study. These blocks were placed in mandibular wax models. The blocks were scanned after drilling (hole preparation) and after implant placement using Cranex3D imaging system with a 4 × 6 cm²and 6 × 8 cm² FOV and 4 and 10 mA. Gray value of the bone blocks was recorded before and after placement of implants.

Results

In general, irrespective of bone density, the amount of artifacts was lower in small FOV compared to large FOV (P < 0.05). Change of mA had no effect on metal artifacts (P > 0.05). Artifacts in type 4 bone were greater than in other bone types (P < 0.05). Difference between type 1 and types 2 and 3 was not significant (P > 0.05).

Conclusion

According to the results of this study, Peri-implant artifacts were seen in all bone types; the amount of artifacts in type 4 bone was higher than that in other types. Size of FOV and bone density affect the metal artifacts around dental implants; so that a smaller FOV can be used to decrease metal artifacts.

Comparative assessment of condylar position in patients with temporomandibular disorder (TMD) and asymptomatic patients using cone-beam computed tomography

BACKGROUND

Temporomandibular disorders (TMD) are the most common reason of non-dental pain in the orofacial region. A clinical examination of the temporomandibular joint (TMJ) with additional imaging is the most recommended procedure for TMD diagnosis.

OBJECTIVES

The objective of this study was to evaluate the association between TMD and the condylar position in the glenoid fossa by examining a group of patients suffering from TMD compared with a control group of patients without TMD. In this study, we used cone-beam computed tomography (CBCT) images for measurements.

MATERIAL AND METHODS

Sixty-five symptomatic joints were selected from 48 patients with TMD. Sixtyfive joints were selected from a total of 96 asymptomatic joints in the control group. The superior, anterior and posterior area of the joint, and the steepness of the articular eminence were measured on the CBCT images. The data was analyzed using Pearson's χ2 test.

RESULTS

The position of the condyle was significantly more posterior in the joints with TMD, and more anterior and centric in the asymptomatic joints. Statistically, the vertical position of the condyle and the steepness of the articular eminence had no significant relation with the occurrence of TMD.

CONCLUSIONS

In this study, we observed that the posterior condylar position is more common in TMD patients, but it is not the reason for diagnosing TMD, and the reason of the posterior position of the condyle should be investigated before any decisions pertaining to treatment are made. In future, studies should focus on evaluating how the position of the condyle will change after the treatment of patients with TMD.

Morphology of maxilla in patients with palatally displaced canines

OBJECTIVES

The aim of this study was to investigate the possible relationship between the morphology of maxilla and the palatally displaced canines (PDC).

MATERIALS AND METHODS

In this cross-sectional study, there were 101 patients (45 males, 56 females) aged 12 to 16years, referred to Hamadan school of dentistry in 2014. They were divided into 3 groups: the bilateral PDC (PDCb) group (male=15, female=21), the unilateral PDC (PDCu) group (male=16, female=19), and the control group (male=14, female=16). Five morphology related variables including intermolar width, maxillary arch length, palatal vault depth, palatal intermolar area, and nasal width were measured using CBCT images with Dolphin Imaging software, version 11.5. Statistical analysis was performed with ANOVA and the Dunnett test using SPSS software, version 16.0.

RESULTS

Only the palatal intermolar area and the palatal vault depth values were significantly less in the PDCu and the PDCb groups than those in the control group (the palatal intermolar area: 376.17, 381.93, and 423.75mm², the palatal vault depth: 13.19, 13.42, and 14.59mm; respectively; P<0.05). For all the variables, there was no statistically significant difference between the PDCu and PDCb groups.

CONCLUSION

Decreased palatal vault depth and palatal intermolar area may be correlated with greater chance of palatal displacement of canines. Future prospective studies in mixed dentition patients are needed as a predictive factor to find the probability of PDC.

Root Morphology and Number of Canals in Mandibular Central and Lateral Incisors Using Cone Beam Computed Tomography

Most failures in endodontic treatment of mandibular incisors are due to the presence of a missed canal specifically the lingual. This investigation aimed to examine the root morphology and number of canals in mandibular incisors using cone beam computed tomography (CBCT). Two hundred and seven patients were assessed in terms of their mandibular central and lateral incisors of CBCT. The inclusion criteria were absence of root resorption, coronal restoration or root filling and clarity and optimal resolution of images. According to the Vertucci's classification, number of roots and canals and type of canal were evaluated by two oral and maxillofacial radiologists. In order to data analysis SPSS version 16 and descriptive statistics were implemented. All mandibular incisors had one root. Most central (84.5%) and lateral (78.2%) incisors had a single canal (p= 0.065). The majority of central (54.5%) and lateral (56.5%) incisors were Vertucci's type I (p= 0.102). Prevalence of one canal in males: central (84.8%), lateral (77.9%) and in females: central (84.2%), lateral (78.5%) (p= 0.518). Prevalence of Vertucci's type I in males: central (52.3%), lateral (45.3%) and in females: central (56.1%), lateral (64.4%) (p=0.188). The prevalence of two canals was 15.5% (central) and 21.8% (lateral) in mandibular incisors. The Vertucci's type I was the most typical kinds of mandibular incisors. Considering the limitations of periapical radiography in determining canal morphology, CBCT can be helpful in case of any concern regarding root canal morphology.

Comparison of pharyngeal airway volume in different skeletal facial patterns using cone beam computed tomography

Background

This study aimed to compare the pharyngeal airway volume in class I,II and III skeletal malocclusion patients using cone beam computed tomography (CBCT).

Material and Methods

This retrospective, cross sectional study was conducted on lateral cephalograms of 71 patients derived from their CBCT scans. Using the ANB angle, the patients were divided into class I,II and III malocclusion. Two observers used Dolphin 3D software to calculate the pharyngeal airway volume, airway area, minimum axial area, minimum area location, airway length and morphology. Data were analyzed using one-way ANOVA, Kruskal-Wallis test, Tukey’s test, Spearman’s correlation coefficient and multiple regression analysis.

Results

The three skeletal classes were significantly different in airway volume, minimum axial area, mean airway area and airway morphology (P<0.05). Significant differences were found in airway volume and mean airway area between class II and III patients (P<0.05). The minimum axial area and airway morphology in class III patients were greater than those in class I and II patients (P<0.05). Every one unit increase in the ANB angle decreased the airway volume by 0.261 units. The effect of ANB angle on airway volume was statistically significant and it was shown that one unit increase in the angle decreased the airway volume by 453.509 units.

Conclusions

A significant correlation exists between the skeletal facial pattern and upper airway dimensions. In our study, the total airway volume and the mean airway area of class III patients were larger than those in class II patients.

Key words:Cone-Beam computed tomography, malocclusion, pharyngeal airway volume.

Does zoledronate therapy make mandibular bone susceptible to fracture? A radiographical and biomechanical study in rats

INTRODUCTION

The aim of this study was to evaluate the effect of zoledronate therapy on susceptibility of mandibular bone to fracture in rats.

METHODS

Fifty rats were randomly allocated to two groups of 25 animals. The rats in group Z received monthly intravenous infusion of 0.06 mg/kg zoledronate for 6 months. The rats in the group C were injected with an equal volume of saline in the same manner. A month after the last zoledronate/saline administration, all 50 rats were euthanized. Using a cone beam computed tomography, the cortical thickness of inferior border of mandible and the mandibular bone mineral density were calculated, and using a three-point bending test, the peak load failure and the ultimate stress of mandibular bone were determined.

RESULTS

The mean mandibular inferior cortical bone thickness and the mean bone mineral density were significantly larger in zoledronate-treated rats (0.30 ± 0.02 mm and 1045.00 ± 185.79, respectively) compared to control rats (0.21 ± 0.01 mm and 878.66 ± 166.53, respectively). The peak load and the ultimate stress were lower in the zoledronate-treated hemimandibles (84.61 ± 33.62 N and 1.76 ± 0.72 MPa, respectively) compared to the control hemimandibles (98.36 ± 16.5 9 N and 2.03 ± 0.44 MPa, respectively).

CONCLUSION

Zoledronate therapy reduced the mechanical strength of the mandibles, implying an increased risk of mandibular fracture in rats.

Performance of Cone Beam Computed Tomography Systems in Visualizing the Cortical Plate in 3D Image Reconstruction: An In Vitro Study

INTRODUCTION

Cortical bone is an important anatomical structure and its thickness needs to be determined prior to many dental procedures to ensure treatment success. Imaging modalities are necessarily used in dentistry for treatment planning and dental procedures. Three-dimensional image reconstruction not only provides visual information but also enables accurate measurement of anatomical structures; thus, it is necessarily required for maxillofacial examination and in case of skeletal problems in this region.

AIMS

This study aimed to assess the ability of three Cone Beam Computed Tomography (CBCT) systems including Cranex 3D, NewTom 3G and 3D Promax for Three-Dimensional (3D) image reconstruction of the cortical plate with variable thicknesses.

METHODS

Depending on the cortical bone thickness, samples were evaluated in three groups of ≤ 0. 5 mm, 0.6 -1 mm and 1.1-1.5 mm cortical bone thickness. The CBCT scans were obtained from each sample using three systems, their respective FOVs, and 3D scans were reconstructed using their software programs. Two observers viewed the images twice with a two-week interval. The ability of each system in the 3D reconstruction of different thicknesses of cortical bone was determined based on its visualization on the scans. The data were analyzed using SPSS and Kappa test.

RESULTS

The three systems showed the greatest difference in the 3D reconstruction of cortical bone with < 0.5 mm thickness. Cranex 3D with 4×6 cm2 FOV had the highest and 3D Promax with 8×8 cm2 FOV had the lowest efficacy for 3D reconstruction of cortical bone. Cranex 3D with 4×6 cm2 and 6×8 cm2 FOVs and NewTom 3G with 5×5 cm2 and 8×5 cm2 FOVs showed significantly higher efficacy for 3D reconstruction of cortical bone with 0.6-1mm thickness while 3D Promax followed by NewTom 3G with 8×8 cm2 FOV had the lowest efficacy for this purpose.

CONCLUSION

Most CBCT systems have high efficacy for 3D image reconstruction of cortical bone with thicknesses over 1 mm while they have poor efficacy for image reconstruction of cortical bone with less than 0.5 mm thickness. Thus, for accurate visualization of anatomical structures on CBCT scans, systems with smaller FOVs and consequently smaller voxel size are preferred.

In vitro effect of changing the horizontal angulation of X-ray beam on the detection of proximal enamel caries in bitewing radiographs

BACKGROUND

Bitewing radiography is an important modality useful for the evaluation of teeth in patients of various ages and in different stages of tooth eruption. Clinical examination of proximal surfaces for caries may result in false negative results, especially in tight contact areas. Thus, radiography, as an adjunct to clinical examination, is used as a routine diagnostic modality for caries detection.

OBJECTIVES

The objective of this study was to assess the in vitro effect of changing the horizontal angulation of X-ray beam on the detection of proximal enamel caries in bitewing radiographs.

MATERIAL AND METHODS

This in vitro study was conducted on 150 caries-free human premolars (code: p/16/35/9/210). The teeth were randomly divided into 3 groups (n = 50). Group 1 served as the control group and no carious lesions were induced in this group. Teeth in groups 2 and 3 were immersed in demineralizing solution for 2 and 4 months, respectively. After induction of caries and its radiographic confirmation, the teeth were mounted in wax in groups of 3 and bitewing radiographs were obtained at 0°, 5°, 10° and 15° horizontal angles.

RESULTS

The sensitivity values of bitewing radiographs at 0°, 5°, 10° and 15° horizontal angles were 88%, 90%, 88%, 92% in group 2 and 88%, 94%, 94% and 94% in group 3, respectively. The specificity values of bitewing radiographs at 0°, 5°, 10° and 15° horizontal angles were 92%, 86%, 84% and 76%. The accuracy of bitewing radiographs at 0°, 5°, 10° and 15° horizontal angles was 89.3%, 90%, 88.7% and 87.3%, respectively. The highest diagnostic accuracy was obtained at 5° horizontal angle for caries detection; however, the difference in this regard among the tested horizontal angles was not statically significant (p = 0.846).

CONCLUSIONS

Based on the results of this study, changing the horizontal angulation has no significant effect on the detection of proximal enamel caries in bitewing radiographs.

Diagnostic accuracy of cone-beam computed tomography scans with high- and low-resolution modes for the detection of root perforations

Purpose

This study compared the diagnostic accuracy of cone-beam computed tomography (CBCT) scans obtained with 2 CBCT systems with high- and low-resolution modes for the detection of root perforations in endodontically treated mandibular molars.

Materials and Methods

The root canals of 72 mandibular molars were cleaned and shaped. Perforations measuring 0.2, 0.3, and 0.4 mm in diameter were created at the furcation area of 48 roots, simulating strip perforations, or on the external surfaces of 48 roots, simulating root perforations. Forty-eight roots remained intact (control group). The roots were filled using gutta-percha (Gapadent, Tianjin, China) and AH26 sealer (Dentsply Maillefer, Ballaigues, Switzerland). The CBCT scans were obtained using the NewTom 3G (QR srl, Verona, Italy) and Cranex 3D (Soredex, Helsinki, Finland) CBCT systems in high- and low-resolution modes, and were evaluated by 2 observers. The chi-square test was used to assess the nominal variables.

Results

In strip perforations, the accuracies of low- and high-resolution modes were 75% and 83% for NewTom 3G and 67% and 69% for Cranex 3D. In root perforations, the accuracies of low- and high-resolution modes were 79% and 83% for NewTom 3G and was 56% and 73% for Cranex 3D.

Conclusion

The accuracy of the 2 CBCT systems was different for the detection of strip and root perforations. The Cranex 3D had non-significantly higher accuracy than the NewTom 3G. In both scanners, the high-resolution mode yielded significantly higher accuracy than the low-resolution mode. The diagnostic accuracy of CBCT scans was not affected by the perforation diameter.

Effect of field-of-view size on gray values derived from cone-beam computed tomography compared with the Hounsfield unit values from multidetector computed tomography scans

Purpose

This study aimed to evaluate the effect of field-of-view (FOV) size on the gray values derived from conebeam computed tomography (CBCT) compared with the Hounsfield unit values from multidetector computed tomography (MDCT) scans as the gold standard.

Materials and Methods

A radiographic phantom was designed with 4 acrylic cylinders. One cylinder was filled with distilled water, and the other 3 were filled with 3 types of bone substitute: namely, Nanobone, Cenobone, and Cerabone. The phantom was scanned with 2 CBCT systems using 2 different FOV sizes, and 1 MDCT system was used as the gold standard. The mean gray values (MGVs) of each cylinder were calculated in each imaging protocol.

Results

In both CBCT systems, significant differences were noted in the MGVs of all materials between the 2 FOV sizes (P<.05) except for Cerabone in the Cranex3D system. Significant differences were found in the MGVs of each material compared with the others in both FOV sizes for each CBCT system. No significant difference was seen between the Cranex3D CBCT system and the MDCT system in the MGVs of bone substitutes on images obtained with a small FOV.

Conclusion

The size of the FOV significantly changed the MGVs of all bone substitutes, except for Cerabone in the Cranex3D system. Both CBCT systems had the ability to distinguish the 3 types of bone substitutes based on a comparison of their MGVs. The Cranex3D CBCT system used with a small FOV had a significant correlation with MDCT results.

Efficacy of denoising and enhancement filters for detection of approximal and occlusal caries on digital intraoral radiographs

Background and Objectives

Image processing and enhancement filters can significantly improve the diagnostic value of digital radiographs. Evidence shows that increasing the contrast and filtering improve the diagnostic accuracy for caries detection. This study sought to assess the diagnostic accuracy of original and enhanced digital radiographs for the detection of approximal and occlusal caries.

Subjects and Methods

In this experimental study, incipient carious lesions were artificially created on 120 proximal and occlusal surfaces of human extracted permanent molar and premolar teeth. After mounting the teeth in wax, digital radiographs were obtained using photostimulable phosphor plates and enhanced by enhancement filters 1, 2, and 3 with/without denoising. Two oral and maxillofacial radiologists blinded to filtering viewed the radiographs and filled out a chart. A definite diagnosis was made by a pathologist by observing the samples under a stereomicroscope (gold standard). Data were analyzed using SPSS software version 16. Interobserver agreement was calculated using kappa statistics. Chi-square test was used to assess the correlation between qualitative variables.

Results

Assessment of sensitivity, specificity, accuracy, positive predictive value, and negative predictive value showed that enhancement filter 2 without denoising was the most efficient and original radiographs (filter free) were the least efficient radiographs for the detection of carious and sound surfaces. Application of filters significantly increased the accuracy of caries detection on digital radiographs. The lowest diagnostic accuracy was noted for the detection of enamel lesions on original radiographs (52%). Enhancement filter 2 plus denoising was the best filter for the detection of these lesions (79.25%). No significant difference was noted among different filters for detection of carious and sound surfaces but enhanced, and original radiographs were significantly different in visualization and detection of caries (P < 0.05).

Conclusion

Application of enhancement filters, particularly enhancement filter 2 with/without denoising, increases the accuracy of caries detection on digital radiographs.

Comparison of the root canal debridement ability of two single file systems with a conventional multiple rotary system in long oval-shaped root canals: In vitro study

Background

This study sought to compare the root canal debridement ability of Neolix, Reciproc and ProTaper rotary systems in long oval-shaped root canals.

Material and Methods

Eighty five extracted single-rooted human teeth with long oval-shaped single root canals were selected and divided into three experimental groups(n=25) and one control group (n= 10). Root canals were filled with Vitapex radiopaque contrast medium and prepared with Neolix, Reciproc or ProTaper systems. The control group only received irrigation. Digital radiographs were obtained at baseline and postoperatively and subjected to digital subtraction. The percentage of reduction in contrast medium was quantified at 0-5 mm and 5-10 mm distances from the apex. The data were analyzed using one-way ANOVA and t-test.

Results

The mean percentage of the contrast medium removed was not significantly different in the 0-5mm segment among the three groups (P=0.6). In the 5-10mm segment a significant difference was found in this regard among the ProTaper and Reciproc groups (P=0.02) and the highest mean percentage of contrast medium was removed by ProTaper. But, difference between ProTaper and Neolix as well as Neolix and Reciproc was not significant. In Neolix (P=0.024) and Reciproc (P=0.002) systems, the mean percentage of the contrast medium removed from the 0-5mm segment was significantly greater than that in 5-10mm segment; however, this difference was not significant in ProTaper group (P=0.069).

Conclusions

Neolix single-file system may be a suitable alternative to ProTaper multiple-file system in debridement of long oval shaped canals.

Key words:Root Canal Preparation, Debridement, Root Canal Therapy.

Effect of changing the head position on accuracy of transverse measurements of the maxillofacial region made on cone beam computed tomography and conventional posterior-anterior cephalograms

OBJECTIVES

This study aimed to assess the effect of head position on the accuracy of transverse measurements of the maxillofacial region on CBCT and conventional posteroanterior (PA) cephalograms. The second objective of this study was to find skull positions with the greatest and smallest effect on transverse measurements in the maxillofacial region.

METHODS

PA cephalograms and CBCT scans were obtained from 10 dry human skulls in 7 positions, namely the central position, 10° and 20° rotations, 10° and 20° tilts and 10° and 20° tips. The CBCT scans were converted to PA cephalograms on which distances from six landmarks, namely the nasal cavity, zygomatic arch, jugale, antegonion, condylion and zygomaticofrontal suture to the mid-sagittal plane, were measured on both sides using Dolphin two-dimensional software. The paired t-test was used to compare the mean values separately in each position (for each landmark) with the gold standard (central skull position). The interclass correlation coefficient and the Bland-Altman plot were used to compare the mean values measured by two observers.

RESULTS

The mean values of the distances measured on CBCT PA cephalograms were greater than those measured on conventional PA cephalograms; this difference was statistically significant for some landmarks (p < 0.005). The rotated position (as compared with the central position) caused the greatest change in values for most landmarks on both sides (p < 0.005).

CONCLUSIONS

The CBCT PA cephalogram was more accurate than the conventional PA cephalogram, and landmarks farther from the midline exhibited greater changes on cephalograms compared with those closer to the midline. Patients are at risk of improper positioning when undergoing extraoral radiography such as PA cephalograms. Changes in head position may affect the transverse measurements and thus the treatment plan.

Comparison of Ultrasonography, Magnetic Resonance Imaging and Cone Beam Computed Tomography for Detection of Foreign Bodies in Maxillofacial Region

INTRODUCTION

Foreign Bodies (FBs) entrapped in the maxillofacial region have a high prevalence due to trauma and accidents. Accurate localization of FBs and verifying their type and size are critical to assist the surgeon in their fast retrieval with minimal tissue damage.

AIM

To assess and compare the imaging modalities including MRI, ultrasonography and Cone Beam Computed Tomography (CBCT) for detection of different types of FBs.

MATERIALS AND METHODS

In this study, four types of FBs including pieces of normal glass, barium glass, wood and pebbles with equal sizes were placed randomly in two sheep heads in different locations such as upper lip, maxillary sinus and body of mandible as FBs and subjected to MRI, ultrasound and CBCT. The images were interpreted by expert observers and the data was analysed using the stata 11 software, kappa test and chi-square test.

RESULTS

Sensitivity of CBCT, MRI and ultrasound for detecting foreign bodies was 79.19%, 20.83% and 33.33%, respectively. None of the imaging modalities could clearly visualize wooden FBs. Among different FBs, pebbles and barium glass were detected more accurately by radiographic imaging technique. The sensitivity of CBCT, ultrasound and MRI for pebbles was 100%, 33.33% and 16.67%, respectively. The sensitivity of CBCT, ultrasound and MRI for barium glass was 100%, 33.33% and 41.69%, respectively. The sensitivity of CBCT, ultrasound and MRI for wood was 33.33%, 33.33% and 16.67%, respectively. Specificity of all three imaging modalities was 100%. Diagnostic accuracy of all three imaging modalities was higher for detection of FBs in the upper lip than those in the body of mandible, and FBs in the latter location had higher detection accuracy than those in the maxillary sinus.

CONCLUSION

Among the three imaging modalities, CBCT had the highest diagnostic sensitivity for the examined FBs. The highest diagnostic sensitivity was noted for pebbles and barium glass.

Comparison of Cone-Beam Computed Tomography and Intraoral Radiography in Detection of Recurrent Caries under Composite Restorations

Abstract Secondary caries is the most common cause of dental restoration failures. This study aimed to compare the diagnostic accuracy of conventional and digital intraoral radiography and cone beam computed tomography (CBCT) for detection of recurrent caries around composite restorations. mesio-occluso-distal (MOD) cavities were prepared using bur on 45 extracted sound human molar teeth. The teeth were divided into 3 groups. In the control group, cavities were restored with composite resin after etching and bonding (n=15). In Group 2, 500-μm thick wax was placed over the buccal, lingual and gingival walls and the cavities were restored with composite resin. Group 3 specimens were subjected to pH cycling and artificial caries were created on the buccal, lingual and gingival walls. The cavities were restored with composite. Conventional and digital photo-stimulable phosphor (PSP; Optime) radiographs and two CBCTs images (NewTom 3G and Cranex 3D) were obtained from them. Presence or absence of caries in the cavity walls was assessed on these images. Data were analyzed using Kappa statistic. The diagnostic accuracy of CBCT was significantly higher than that of digital and conventional intraoral radiography (p<0.05). The accuracy was 0.83, 0.78, 0.55 and 0.49 for CBCT Cranex 3D, CBCT NewTom 3G, conventional and digital intraoral radiography, respectively. CBCT has a higher diagnostic accuracy than digital and conventional intraoral radiography for detection of secondary caries around composite restorations.

Effect of Head Position on Maxillofacial Transverse Measurements Made on the Skull and Cone Beam Computed Tomography Scans

Article Incorrect patient positioning and the resultant image distortion occur in many radiographic examinations. This study aimed to assess the effect of tilting, rotation and tipping of the head on the accuracy of maxillofacial transverse measurements made on cone beam computed tomography (CBCT) scans. The CBCT scans were obtained in central position of 10 dry human skulls. Using three-dimensional (3D) Dolphin software, six positions namely 10° and 20° tilts, rotations and tips were reconstructed of central position. Transverse distances between landmarks were measured on 3D scans and the skulls. The intraclass correlation coefficient (ICC) and the Bland-Altman plot were used to compare the mean values measured by the two observers. For most landmarks, no significant differences were noted between the mean transverse distances measured in the six positions and those measured in central position on 3D scans (p>0.005). In conclusion, all measurements of transverse distances made on 3D scans in different positions were underestimated compared to the actual values measured on the skull.

Application of multiplex PCR for the simultaneous detection of Taenia spp. from domestic dogs in the north of Iran

The family Taeniidae is of great importance in the medical and veterinary fields, particularly in the tropics and subtropics. Identification of eggs of different Taenia spp. in the final host by morphological examination is difficult owing to their similarity. Therefore, a multiplex polymerase chain reaction (PCR) targeting a mitochondrial gene was applied to identify morphologically indistinguishable eggs. Fecal samples from 100 domestic dogs, from the Mazandaran province in Iran, were examined using the flotation/sieving method followed by multiplex PCR. Taeniid eggs were observed in 24 % samples, of which 12 %, 10 %, and 2 % were infected with Echinococcus granulosus, Taenia spp., and both E. granulosus and Taenia spp., respectively. E. multilocularis was absent in these samples. The prevalence of E. granulosus in the examined domestic dogs as definitive hosts in north of Iran was high (14 %). Therefore, people living in this region of Iran are in danger of acquiring hydatid cyst, which is a serious public health problem.