Scattered Radiation Distribution Utilizing Three Different Cone-Beam Computed Tomography Devices for Maxillofacial Diagnostics: A Research Study.

This study aimed to estimate scattered radiation and its spatial distribution around three cone-beam computed tomography (CBCT) devices, in order to determine potential positions for an operator to stand if they needed to be inside the CBCT room. The following devices were tested: Morita Accuitomo (CBCT1), Newtom Giano HR (CBCT2), Newtom VGi (CBCT3). Scattered radiation measurements were performed using different kVp, mA, and Field of View (FOV) options. An anthropomorphic phantom (NATHANIA) was placed inside the X-ray gantry to simulate clinical conditions. Scattered measurements were taken with the Inovision model 451P Victoreen ionization chamber once placed at fixed distances from each irradiation isocenter, away from the primary beam. A statistically significant (p < 0.001) difference was found in the mean value of the scattered radiation estimations between the CBCT devices. Scattered radiation was reduced with a different rate for each CBCT device as distance was increased. For CBCT1 the reduction was 0.047 µGy, for CBCT2 it was 0.036 µGy, and for CBCT3 it was 0.079 µGy, for every one meter from the X-ray gantry. Therefore, at certain distances from the central X-ray, the scattered radiation was below the critical level of 1 mGy, which is defined by the radiation protection guidelines as the exposure radiation limit of the general population. Consequently, an operator could stay inside the room accompanying the patient being scanned, if necessary.

Morphological Assessment of Nasopalatine Canal Using Cone Beam Computed Tomography: A Retrospective Study of 124 Consecutive Patients.

This study aimed to assess and analyze the morphology and dimensions of the nasopalatine canal (NPC), as well as the adjacent buccal osseous plate (BOP), and to investigate the effect of gender, edentulism, NPC types, absence of maxillary central incisors (ACI) and age on the NPC and BOP, using cone beam computed tomography (CBCT). A total of 124 CBCT examinations (67 female and 57 male patients) were retrospectively included and evaluated. The assessment of the dimensions of the NPC, as well as the dimensions of the adjacent BOP, was performed by three Oral and Maxillofacial Radiologists on reconstructed sagittal and coronal CBCT sections under standardized conditions. Regarding the dimensions of the NPC and the adjacent BOP, the mean values were significantly higher among males than females. Furthermore, edentulous patients showed a significant reduction in BOP dimensions. Additionally, NPC types showed a significant effect on the length of the NPC, and the ACI had a significant effect on reducing BOP dimensions. Age had a significant effect on the diameter of the incisive foramen, with the mean values generally increasing with an increasing age. CBCT imaging of this anatomical structure contributes significantly to its full assessment.

The effect of nano-hydroxyapatite/chitosan scaffolds on rat calvarial defects for bone regeneration.

BACKGROUND: This study aims at determining the biological effect of 75/25 w/w nano-hydroxyapatite/chitosan (nHAp/CS) scaffolds on bone regeneration, in terms of fraction of bone regeneration (FBR), total number of osteocytes (Ost), and osteocyte cell density (CD), as well as its biodegradability. METHODS: Two critical-size defects (CSDs) were bilaterally trephined in the parietal bone of 36 adult Sprague-Dawley rats (18 males and 18 females); the left remained empty (group A), while the right CSD was filled with nHAp/CS scaffold (group B). Two female rats died postoperatively. Twelve, 11, and 11 rats were euthanized at 2, 4, and 8 weeks post-surgery, respectively. Subsequently, 34 specimens were resected containing both CSDs. Histological and histomorphometric analyses were performed to determine the FBR, calculated as [the sum of areas of newly formed bone in lateral and central regions of interest (ROIs)]/area of the original defect, as well as the Ost and the CD (Ost/mm2) in each ROI of both groups (A and B). Moreover, biodegradability of the nHAp/CS scaffolds was estimated via the surface area of the biomaterial (BmA) in the 2nd, 4th, and 8th week post-surgery. RESULTS: The FBR of group B increased significantly from 2nd to 8th week compared to group A (P = 0.009). Both the mean CD and the mean Ost values of group B increased compared to group A (P = 0.004 and P < 0.05 respectively). Moreover, the mean value of BmA decreased from 2nd to 8th week (P = 0.001). CONCLUSIONS: Based on histological and histomorphometric results, we support that 75/25 w/w nHAp/CS scaffolds provide an effective space for new bone formation.

Extraoral surgical removal of an ectopic impacted third molar of the mandible. Report of a case.

Intraoral approach for the removal of impacted third molars represents a common surgical procedure for the specialized clinician. However, in some cases such as ectopic third molars, extraoral surgical removal seems to be inevitable. We present a step by step case of a 56 year old woman with an ectopic third molar of the lower jaw along with a cystic lesion, which were surgically removed by a submandibular approach. Postoperative clinical course was uneventful and there were no signs of facial nerve paresis. In such cases, appropriate preoperative planning must be made based on careful study of radiographic imaging and clinical examination. The more conservative technique that would minimize adjacent anatomic structures risk should be the surgical technique of choice. Key words:Ectopic third molar, mandible, cyst, extraoral approach.

Imaging of nano-hydroxyapatite/chitosan scaffolds using a cone beam computed tomography device on rat calvarial defects with histological verification.

OBJECTIVES: Τhis study aims at determining the ability of cone beam computed tomography (CBCT) to visualize critical-size defects (CSD) created at rat calvaria and filled with 75/25 w/w nano-hydroxyapatite/chitosan (nHAp/CS) scaffolds, prior to their histological investigation. MATERIALS AND METHODS: Thirty adult Sprague Dawley rats, 15 males and 15 females, were used. Two CSD, 5 mm in diameter, were bilaterally trephined in the parietal bone. The right CSD was filled with nHAp/CS scaffold, while the left CSD remained empty, as the control group. Two female rats died post-operatively. Rats were euthanized at 2, 4, and 8 weeks post-surgery. Twenty-eight specimens (15 × 2 × 10 mm) were resected-containing both CSDs-and then scanned using a NewTom VGi CBCT imaging unit (Verona, Italy). The manufacturer's software trace region profile tool (NNT v6.2, Verona, Italy) was used in selected axial slices. The greyscale value (in VGiHU) and the traced/selected region of interest (ROI, in mm2) of those areas were automatically calculated. Subsequently, all specimens were histologically examined. RESULTS: An increased VGiHU (P = 0.000), was observed in the experimental group relative to the control group. The ROI of CSD (in mm2) was significantly reduced (P = 0.001) from the fourth to the eighth week in both groups. No statistically significant difference between male and female rats (P = 0.188) was observed with respect to VGiHU. CONCLUSIONS: The nHAp/CS scaffolds are easily visualized using a particular high-resolution CBCT device. CLINICAL RELEVANCE: Both the CBCT measurements and also the histological results suggest that the nHAp/CS scaffold presence contributes to new bone formation in rat calvarial CSD.

Estimating cancer risk from dental cone-beam CT exposures based on skin dosimetry.

The aim of this study was to measure entrance skin doses on patients undergoing cone-beam computed tomography (CBCT) examinations, to establish conversion factors between skin and organ doses, and to estimate cancer risk from CBCT exposures. 266 patients (age 8-83) were included, involving three imaging centres. CBCT scans were acquired using the SCANORA 3D (Soredex, Tuusula, Finland) and NewTom 9000 (QR, Verona, Italy). Eight thermoluminescent dosimeters were attached to the patient's skin at standardized locations. Using previously published organ dose estimations on various CBCTs with an anthropomorphic phantom, correlation factors to convert skin dose to organ doses were calculated and applied to estimate patient organ doses. The BEIR VII age- and gender-dependent dose-risk model was applied to estimate the lifetime attributable cancer risk. For the SCANORA 3D, average skin doses over the eight locations varied between 484 and 1788 µGy. For the NewTom 9000 the range was between 821 and 1686 µGy for Centre 1 and between 292 and 2325 µGy for Centre 2. Entrance skin dose measurements demonstrated the combined effect of exposure and patient factors on the dose. The lifetime attributable cancer risk, expressed as the probability to develop a radiation-induced cancer, varied between 2.7 per million (age >60) and 9.8 per million (age 8-11) with an average of 6.0 per million. On average, the risk for female patients was 40% higher. The estimated radiation risk was primarily influenced by the age at exposure and the gender, pointing out the continuing need for justification and optimization of CBCT exposures, with a specific focus on children.

Antimicrobial efficacy of denture adhesives on some oral malodor-related microbes.

The objective of the study was to determine the antimicrobial efficacy of three denture adhesives toward Streptococcus oralis, mutans, Prevotella oralis and Fusobacterium nucleatum. Adhesives used were Corega Ultra(®), Fixodent Pro Original(®) and Biotene(®) Denture Grip. For Streptococcus oralis and Streptococcus mutans, four tubes of Trypticase Soy Broth 10 mL and 1 g denture of adhesive were used. In addition four tubes of Trypticase Soy Broth 10 mL without any denture adhesive was employed as control. For Prevotella oralis and Fusobacterium nucleatum, four tubes of thioglycolate 10 mL and 1 g denture adhesive were used for each one, while four tubes of thioglycolate 10 mL without adhesive served as control. All samples were incubated for 48 h at 37°C. After 48 h, the number of colonies was counted and the mean was extracted as cfu/mL. The results were evaluated with ANOVA on ranked data and Tukey's post hoc test at α = 0.05. Streptococcus oralis, mutans, Prevotella oralis and Fusobacterium nucleatum showed decreased number of colonies for each denture adhesive compared to the control. Under the conditions of this in vitro study, all the tested denture adhesives showed antimicrobial efficacy. However, in contrast to the hypothesis, there were differences among them. Corega Ultra(®) and Biotene(®) Denture Grip were more effective for all the tested oral malodor-related microbes than Fixodent Pro Original(®).

Increased TNF-α, IL-6 and decreased IL-1ß immunohistochemical expression by the stromal spindle-shaped cells in the central giant cell granuloma of the jaws.

OBJECTIVES: the expression of the osteoclastogenic cytokines TNF-α, IL-6 and IL-1ß were immunohistochemically evaluated in peripheral (PGCG) and central (CGCG) giant cell granulomas of the jaws in order to determine differences between these two lesions and between the two distinct tumor cell populations (multinucleated giant cells, MGCs and stromal spindle-shaped cells). STUDY DESIGN: Paraffin-embedded tissue sections from 40 PGCG and 40 CGCG were immunohistochemically stained using antibodies against TNF-α, IL-6 and IL-1ß. The percentage of positively stained cells and the staining intensity were assessed to provide a combined immunoreactivity score value. RESULTS: TNF-α, IL-6 and IL-1ß were expressed in all lesions. The CGCG compared to the PGCG showed significantly increased expression of TNF-α and IL-6 and decreased expression of IL-1ß by the spindle-shaped cells and increased expression of IL-1ß by the MGCs. The MGCs demonstrated in comparison to the stromal spindle-shaped cells significantly increased expression of all three cytokines in both PGCG and CGCG. CONCLUSIONS: The proinflammatory cytokines TNF-α, IL-6 and IL-1ß seem to be involved in the growth process of PGCG and CGCG of the jaws. A possible alteration in the synthesis or/and activity of these cytokines by the stromal spindle cells in the CGCGs may enhance osteolysis through the stimulation of osteoclast progenitor cells, given the fact that the intraosseous lesions cause bone resorption.

Radiation dose reduction in direct digital panoramic radiography.

OBJECTIVES: (a) To measure the absorbed radiation doses at 16 anatomical sites of a Rando phantom and (b) to calculate the effective doses including and excluding the salivary gland doses in panoramic radiography using a conventional and a digital panoramic device. STUDY DESIGN: Thermoluminescent dosimeters (TLD-100) were placed at 16 sites in a Rando phantom, using a conventional, Planmeca Promax and a digital, Planmeca PM2002CC Proline 2000 (Planmeca Oy, 00880 Helsinki, Finland) panoramic device for panoramic radiography. During conventional radiography the selected exposure settings were 66 kVp, 6 mA and 16s, while during digital radiography two combinations were selected 60 kVp, 4 mA, 18 s and 66 kVp, 8 mA, 18s with and without image processing function. The dosimeters were annealed in a PTW-TLDO Harshaw oven. TLD energy response was studied using RQN beam narrow series at GAEC's Secondary Standard Calibration Laboratory. The reader used was a Harshaw, 4500. Effective dose was estimated according to ICRP(60) report (E(ICRP60)). An additional estimation of the effective dose was accomplished including the doses of the salivary glands (E(SAL)). A Wilcoxon signed ranks test was used for statistical analysis. RESULTS: The effective dose, according to ICRP report (E(ICRP60)) in conventional panoramic radiography was 17 microSv and E(SAL) was 26 microSv. The respective values in digital panoramic radiography were E(ICRP60)=23 microSv and E(SAL)=38 microSv; while using the lowest possible radiographic settings E(ICRP60) was 8 microSv and E(SAL) was 12 microSv. CONCLUSIONS: The effective dose reduction in digital panoramic radiography can be achieved, if the lowest possible radiographic settings are used.

Dose reduction in maxillofacial imaging using low dose Cone Beam CT.

OBJECTIVES: (a) To measure the absorbed dose at certain anatomical sites of a RANDO phantom and to estimate the effective dose in radiographic imaging of the jaws using low dose Cone Beam computed tomography (CBCT) and (b) to compare the absorbed and the effective doses between thyroid and cervical spine shielding and non-shielding techniques. STUDY DESIGN: Thermoluminescent dosimeters (TLD-100) were placed at 14 sites in a RANDO phantom, using a Cone Beam CT device (Newtom, Model QR-DVT 9000, Verona, Italy). Dosimetry was carried out applying two techniques: in the first, there was no shielding device used while in the second one, a shielding device (EUREKA!, TRIX) was applied for protection of the thyroid gland and the cervical spine. Effective dose was estimated according to ICRP(60) report (E(ICRP)). An additional estimation of the effective dose was accomplished including the doses of the salivary glands (E(SAL)). A Wilcoxon Signed Ranks Test was used for statistical analysis. RESULTS: In the non-shielding technique the absorbed doses ranged from 0.16 to 1.67 mGy, while 0.32 and 1.28 mGy were the doses to the thyroid and the cervical spine, respectively. The effective dose, E(ICRP), was 0.035 mSv and the E(SAL) was 0.064 mSv. In the shielding technique, the absorbed doses ranged from 0.09 to 1.64 mGy, while 0.18 and 0.95 mGy were the respective values for the thyroid and the cervical spine. The effective dose, E(ICRP), was 0.023 mSv and E(SAL) was 0.052 mSv. CONCLUSIONS: The use of CBCT for maxillofacial imaging results in a reduced absorbed and effective dose. The use of lead shielding leads to a further reduction of the absorbed doses of thyroid and cervical spine, as well as the effective dose.