Evaluation of two-dimensional lateral cephalogram and three-dimensional cone beam computed tomography superimpositions: a comparative study.

Superimposition of radiographic imaging is used to evaluate patient growth and the effects of surgical and/or orthodontic treatment. The purpose of this study was to compare the outcomes of superimposition between two-dimensional (2D) and three-dimensional (3D) superimpositions. 2D lateral cephalograms were generated from the initial and final cone beam computed tomography scans (CBCT) of 18 patients and superimposed. Both 3D CBCT and 2D CBCT generated lateral cephalograms were oriented to the Frankfort horizontal plane and superimposed according to the American Board of Orthodontics recommendations. Changes in landmark position were quantified from the resulting superimposition outcomes via linear measurements made with Dolphin software. Differences between the two methods were analyzed using paired t-tests. Measurements were repeated twice for 10 randomly selected scans to assess reliability by intra-class correlation coefficient (ICC) analysis. Intra-examiner reliability was high for all measurements (ICC>0.84). Agreement between 2D and 3D superimposition outcomes, as measured by P-values, was low for ANS (P=0.026), B-point (P<0.001), ST Upper lip (P=0.019), U1 tip (P=0.010), and U1 apex (P=0.026). 2D measurements were significantly higher than 3D measurements for ANS, B-point, ST Upper lip, U1 tip, and U1 apex. Findings indicated that both methods of superimposition (2D and 3D) are highly reliable. Statistical differences between 2D and 3D superimposition outcomes were below the threshold of clinical significance.

Accuracy and reliability of landmark-based, surface-based and voxel-based 3D cone-beam computed tomography superimposition methods.

OBJECTIVES: To evaluate and compare the accuracy and reliability of 3 different methods of three-dimensional cone-beam computed tomography scans (3D CBCTs) superimpositions: landmark-based, surface-based and voxel-based. MATERIALS AND METHODS: Pre- and post-orthodontic treatment CBCTs (T1 and T2) of 20 subjects with a mean age of 11 years were obtained. Seven points on the zygomatic arch and supraorbital region were selected to perform landmark-based superimposition. Surface-based and voxel-based superimpositions were performed using the anterior cranial base as a reference. Each superimposition method of T1 and T2 scans was repeated twice to assess the reliability. Accuracy of each technique was tested by superimposing duplicated sets of T1 scans. A total of 11 landmarks on the anterior cranial base, maxilla and mandible were located, and deviations of these landmarks on superimposed data were quantified to assess reliability and accuracy of all superimpositions. RESULTS: There were no significant differences from zero when duplicated sets of T1 scans were superimposed using surface-based and voxel-based methods. Statistical significant differences were detected in several parameters when evaluating the accuracy of the landmark superimposition. Superimposition of T1 and T2 scans for testing the reliability revealed intraclass correlation coefficients greater than 0.90 for all measurements except for ACP-x and PNS-y of landmark-based method as well as ANS-x of voxel-based method. CONCLUSIONS: Surface-based and voxel-based superimposition methods using the anterior cranial base as a reference structure were accurate and reliable in detecting changes in landmark positions when superimposing. Landmark-based superimposition method was reliable but less accurate than the other methods.

Effects of tobacco on cytokine expression from human endothelial cells.

OBJECTIVE: To investigate the effects of nicotine and cigarette smoke condensate (CSC) exposure on cytokine expression from human endothelial cells in order to identify one possible mechanism that smoking plays in the pathogenesis of both periodontal disease (PDD) and cardiovascular disease (CVD). METHODS: Human endothelial cells (HUVECs) were exposed to different concentrations of nicotine and CSC to examine the effects that they have on cell proliferation and cytotoxicity. Non-toxic levels were then used to examine cytokine expression using cytokine protein arrays. RESULTS: Exposure to nicotine caused significant down-regulation in the expression of IL-10 (P = 0.046), growth-regulated oncogene (GRO)α (P = 0.036), MCP-1 (P = 0.046), and GMCSF (P = 0.004) compared with the control untreated HUVECs. Exposure to CSC caused significant down-regulation in the expression of GRO (P = 0.04), GROα (P = 0.01), IL-6 (P = 0.03), and MCP-1 (P = 0.04) compared with the control untreated HUVECs. CONCLUSIONS: Exposure of HUVECs to nicotine or CSC affects the levels of cytokine expression including reduction in anti-inflammatory and chemoattractant cytokines. This may subsequently affect the host defensive mechanisms of the tissues. The action of toxic chemicals in tobacco smoke on endothelial cells is a potential pathogenic mechanism that may in part explain the association between tobacco, PDD, and CVD.

The reliability and reproducibility of cephalometric measurements: a comparison of conventional and digital methods.

OBJECTIVE: The aim of this study was to assess the reliability and reproducibility of angular and linear measurements of conventional and digital cephalometric methods. METHODS: A total of 13 landmarks and 16 skeletal and dental parameters were defined and measured on pre-treatment cephalometric radiographs of 30 patients. The conventional and digital tracings and measurements were performed twice by the same examiner with a 6 week interval between measurements. The reliability within the method was determined using Pearson's correlation coefficient (r²). The reproducibility between methods was calculated by paired t-test. The level of statistical significance was set at p < 0.05. RESULTS: All measurements for each method were above 0.90 r² (strong correlation) except maxillary length, which had a correlation of 0.82 for conventional tracing. Significant differences between the two methods were observed in most angular and linear measurements except for ANB angle (p = 0.5), angle of convexity (p = 0.09), anterior cranial base (p = 0.3) and the lower anterior facial height (p = 0.6). CONCLUSION: In general, both methods of conventional and digital cephalometric analysis are highly reliable. Although the reproducibility of the two methods showed some statistically significant differences, most differences were not clinically significant.

In vivo effects of zoledronic acid on oral mucosal epithelial cells.

OBJECTIVE: Osteonecrosis of the jaw is a serious complication of bisphosphonate treatment for which the pathophysiology is unknown. The purpose of this study was to investigate whether in vivo zoledronic acid (ZA) induces alterations in cell proliferation, apoptosis, and matrix metalloproteinases (MMPs) expression in oral mucosal epithelial cells. METHODS: One-year-old dogs were either untreated (control group) or given high doses of intravenous ZA (ZA group) for 3 months. The doses of ZA were equivalent to those given to cancer patients, yet were administered two times more frequently (every 2 weeks). Mucosal tissues were assessed immunohistochemically for cell proliferation (proliferating cell nuclear antigen, PCNA), matrix metalloproteinase (MMP) expression, and apoptosis (caspase 3 and TUNEL). RESULTS: There were no significant differences between the groups with respect to PCNA, MMP-2, MMP-14, and TUNEL positive cells. However, the expression of MMP-9 was significantly higher in the control group than in the ZA group (P < 0.05), whereas the expression of caspase 3 was significantly lower in the control group than in the ZA group (P < 0.05). CONCLUSION: These results suggest that high doses of ZA resulted in higher levels of apoptosis and lower levels of MMP-9 in the oral epithelial cells supporting the idea of bisphosphonate treatment affects the oral mucosa.

Bisphosphonates treatment and orthodontic considerations.

Currently, the use of oral and systemic forms of bisphosphonates is increasing dramatically in a large group of patients either in the form of anti-osteoporosis medications or as a part of a chemotherapeutic regimen for several malignant diseases. As adult orthodontic treatment has become more widely accepted in most orthodontic practices, orthodontists must be aware of the risks, benefits, and effects of bisphosphonates use on the patient's general health status, as well as on their orthodontic treatment outcomes. This review aims to discuss the use of bisphosphonates, the complications associated with their use, and their impact on orthodontic treatment.