Evaluation of the concavity depth and inclination in jaws using CBCT

Introduction: Nowadays, using implants as a choice in patient's treatment plans has become popular. The aim of this study was to determine the prevalence of mandibular lingual and maxillary buccal concavity, mean concavity depth and angle and its relation to age and gender. Materials &Methods: In 200 CBCT, concavity depth and angle were measured in 2 mm superior to the inferior alveolar canal in the mandibular first molar area and in 1 mm distance from nasal floor in the midpoint region of maxillary lateral incisor and canine. Concavity depth and angle relationships with age and gender have been evaluated using Spearman Correlation and a t-test. Results: Mean and standard deviation of lingual concavity, concavity angle and ridge angle in mandible were 1.3±1.54 mm, 15.45±16.19 and 10.13±6.1. Mean and standard deviation of buccal concavity and concavity angle in maxilla were 5.35±1.03 mm and 30.6±5.75. Mandibular concavity depth was zero in 44% of subjects and more than zero in 56%. Results were more than 3 mm in maxillary samples. There was a linear relationship between mandibular concavity depth and age equaled to -0.27, p=0.007 and for mandibular concavity angle and age equaled to -0.25, p=0.01. There was no significant relationship between mandibular ridge angle and age. In maxilla, there was no linear relationship between age and gender with any other variables. Conclusion: It is necessary to provide more information on these regions' anatomy using CBCT cross sections before implant placement

Effect of Spatial Position in the Field of View on Dimensional Changes in Cone Beam Computed Tomography

Objectives: This study aimed to assess the relation between dimensional changes and object location in the field of view (FOV) using cone beam computed tomography (CBCT).  Materials and Methods: A custom-made phantom was fabricated from base plate wax. To analyze the accuracy of measurements in horizontal and longitudinal dimensions, aluminum squares (0.5 mm thickness, 10×10 mm dimensions) were constructed and placed in three levels (upper, middle, and lower) and five positions (central, right, left, anterior and posterior). This phantom was scanned using Asahi, Planmeca and NewTom CBCT systems. CBCT scans were measured three times by use of their corresponding software. Statistical analysis was performed using one-way ANOVA, post-hoc test and two-way ANOVA (P<0.05). Results: The differences between the mean horizontal dimensions of different systems were not significant (P=0.296). However, the differences between the mean longitudinal dimensions of different systems were significant (P=0.039). The differences between the different positions and the mean horizontal and longitudinal dimensions were significant (P<0.001, and P<0.001, respectively). The differences between the mean horizontal dimensions and different levels were not significant (P=0.51), but the differences between the mean longitudinal dimensions and different levels were significant (P<0.001). The interaction effect of level and position on the accuracy of horizontal and longitudinal measurements was significant (P<0.0001). Conclusions: We found statistically significant differences in most of our comparisons; however, these differences were not clinically significant. Therefore, CBCT could be an accurate device for measurement of dimensions of objects placed in different positions in the FOV.

Assessment of Location and Anatomical Characteristics of Mental Foramen, Anterior Loop and Mandibular Incisive Canal Using Cone Beam Computed Tomography

Objectives: This study aimed to evaluate the location and characteristics of mental foramen, anterior loop and mandibular incisive canal using cone beam computed tomography (CBCT). Materials and Methods: This retrospective cross-sectional study evaluated 200 mandibular CBCT scans for the location of mental foramen, anterior loop prevalence and mandibular incisive canal visibility, its mean length and distance to buccal and lingual plates and inferior border of the mandible. The effect of age and gender on these variables was also analyzed (P<0.05). Results: Anterior loop and mandibular incisive canal were seen in 59.5% and 97.5% of the cases, respectively. The mean length of the mandibular incisive canal was 10.48±4.53mm in the right and 10.40±4.52mm in the left side. The mean distance from the endpoints of the canal to buccal plate was 3.63±1.73mm in the right and 3.66±1.45mm in the left side. These distances were 3.89±1.53mm in the right and 4.13±1.48mm in the left side to lingual plate and 9.98±2.07mm in the right and 8.62±1.97mm in the left side to the inferior border of the mandible. The distance from the endpoints of the canal to lingual plate was significantly different in the right and left sides. The distance from the endpoint of the canal to the buccal plate and inferior border of the mandible was significantly shorter in females (P=0.016), and had a weak, significant correlation with age (rsp=0.215, P=0.003). Conclusions: Due to variability in mandibular incisive canal length and high prevalence of anterior loop, CBCT is recommended before surgical manipulation of interforaminal region. Keywords: Anatomic Landmarks; Cone-Beam Computed Tomography; Mandible; Mandibular Nerv

Evaluation of Morphology and Anatomical Measurement of Nasopalatine Canal Using Cone Beam Computed Tomography

Objectives: Precise radiographic assessment of the nasopalatine canal is required to prevent implant failure. The purpose of the current study was to determine the three dimensional (3D) morphology, as well as the dimensions of the nasopalatine canal using cone beam computed tomography (CBCT). Materials and Methods: In this descriptive cross-sectional study, maxillary CBCT images from 300 patients (150 men, 150 women) were retrospectively evaluated. Sagittal and coronal views were reviewed to determine the nasopalatine canal morphology and dimensions. The difference in canal dimensions between men and women was evaluated using the Student’s t-test while the difference in canal morphology between the two sexes was assessed using Chi-square test. Results: A total of 199 (66.3%) patients had type A canal (cylindrical without a branch), 69 (23%) had type B canal (a canal with a branch in the upper part), and 32 (10.7 %) had type C canal (a canal with a branch in the middle part). Incisive foramen diameter was 4.7±1.11mm on the sagittal section. Alveolar bone width in the anterior part of the canal was 12.3±1.7mm in the upper one third, 10.7±1.7mm in the middle one third, and 9.8±1.4mm in the lower one third. The angle of canal with palate was 109.5±5.7°. On the coronal sections, canal length was 14.1±3.0mm, incisive foramen diameter was 4.6±1.0mm, and canal diameter in the nasal floor was 5.1±1.0mm.                           Conclusions: Significant differences in canal morphology were observed among the patients and CBCT was useful in determining nasopalatine canal morphology and its dimensions before implant placement.

Effect of Exposure Parameters on Metal Artifacts in Cone Beam Computed Tomography

Objectives: The aim of this study was to assess the effect of tube current, kilovoltage peak (kVp), metal type, and the position of metal objects on metal artifacts in cone-beam computed tomography (CBCT) images. Materials and Methods: Titanium and cobalt-chromium rods were fabricated and placed in a dry human mandible. Samples were scanned using a Promax 3D CBCT unit with different milli-amperages and kVp. The artifacts induced by metal objects were evaluated using the Image J software in four regions of interest (ROIs) on each image. Results: A higher kVp decreased artifacts of the buccal surface of the rods in 97% of the cases (P=0.046) but did not affect the severity of artifacts between the two metal objects (P>0.05). Increasing the tube current had no effect on metal artifacts in 93% of the cases (P>0.05). Artifacts induced by a cobalt-chromium alloy were more severe than those with titanium (P<0.001). Artifacts were more intense in the buccal surface of anterior rods compared to the posterior rods (P<0.003). Conclusions: Tube voltage, metal type and the position of metal objects affected the severity of metal artifacts on CBCT images. The metal type had the greatest effect on metal artifact intensity in this study.

Nitrergic and opioidergic systems affect radiographic density and histomorphometric indices in bile-duct-ligated cirrhotic rats

Metabolic bone disease is a major issue in chronic liver disease. Increased production of nitric oxide (NO) and elevation of endogenous opioids have been suggested to occur during cholestasis/cirrhosis. We aimed to investigate the involvement of nitrergic and opioidergic systems in bone loss after bile-ductligation (BDL) in rats using optical density (OD) evaluation and histomorphometric analysis. BDL- and sham-operated (SO) rats received injections of 3 mg/kg Nω-Nitro-L-arginine methyl-esterhydrochloride (L-NAME) as an NO-synthase inhibitor, 10 mg/kg naltrexone (NTX) as an opioid-receptors antagonist or saline once daily for 28 days. Lateral cephalometric radiographs were taken on days 0 and 28 and histomorphometric and biochemical indices were measured. Plasma levels of total bilirubin and alkaline-phosphate were markedly increased in BDL compared with SO rats (p≤0.05). Among the studied variables, osteoclast number/mm trabecular surface showed significant increase in BDL animals compared to controls, which was significantly reduced following NO-synthase inhibition (p≤0.05). Similarly, cortical area slightly decreased in BDL animals in comparison to controls, whereas both LNAME and NTX significantly increased this variable. Following BDL, optical density increased in the skulls of cirrhotic animals and showed a significant decrease after blocking opioid-receptors (p≤0.05). Inhibition of NO-synthase and/or opioid receptors caused significant changes in OD and histomorphometric parameters in BDL rats, both in favor of reducing bone loss. If confirmed by further studies, it seems that manipulation of these systems might be able to improve bone problems in subjects with cholestasis/cirrhosis

Alcohol Induced Osteopenia Can Cause Accelerated Orthodontic Tooth Movement in Male Wistar Rats

Background and Aim: Considering the effect of alcohol on bones, consuming alcohol may have some consequences on orthodontic tooth movement. The present study was aimed to evaluate the effect of alcohol consumption on bone density and orthodontic tooth movement in rats. Materials and Methods: In this experimental study, thirty rats were divided into three groups and underwent 3 weeks of different injection regimen. Group A received no injection while rats in group B and C were infused with saline and a mixture of alcohol and saline respectively. Tooth movement at day 21 was measured by leaf gauge. Optical density was measured using a digital densitometer at the beginning and the end of the experiment around four lateral cephalometric landmarks. One-way analysis of variance (ANOVA) was used to determine the differences in tooth movement. Changes in bone density were analyzed using paired T-test after evaluation of interactions. Results: Mean tooth movement in group C was (0.4± 0.06 mm) was significantly higher than no injection (0.26 ± 0.04 mm) and saline infusion (0.29 ± 0.04 mm) groups (P=0.001). Significant decrease in bone density were observed in alcohol injected group in skull (P=0.005) and mandible(P=0.004) after three weeks of experiment. Conclusion: Alcohol infusion could induce decreased bone density which might be a reason for faster tooth movement in alcohol-treated rats

Navigating the Path to Trustworthy Health Guidelines: Exploring Challenges and Imperative Requirements

Looking at guideline development process from a system level perspective requires additional considerations and guidance tailored to the unique challenges and complexities of the health system. Therefore, a complementary framework that can supplement the existing tools and offer comprehensive guidance on effectively addressing system-level factors that influence the development and implementation of guidelines on a broader scale would be a valuable contribution. Establishing such a system level framework that ensures consistency and quality of guidelines, guides developers smoothly through the process, and promotes the trustworthiness of the guidelines while integrating with other decisions in health system, will not be possible without adequate understanding and knowledge of the barriers and facilitators impacting the guideline development. Therefore, this study aims to explore the key elements, barriers and facilitators that influence the system or program of trustworthy guidelines’ production from development and adaptation to updating and dissemination. The findings of this study will be supplemented by insights from expert panel discussions and practical country examples representing operational guideline programs/systems. The panel will share their experiences with guideline development and discuss the challenges they encountered with the support system, further enriching the overall understanding and validating the findings. Work in Estonia that evaluated the country’s guideline program provides important insights and a starting point for this wor

Effect of Fluoxetine Consumption on Orthodontic Tooth Movement in Rats

Objectives: Fluoxetine is a selective serotonin re-uptake inhibitor (SSRI) widely used for depression, bipolar disorder, anxiety and obsessive-compulsive disorder. The aim of this study was to assess the effect of fluoxetine on orthodontic tooth movement (OTM) in rats. Materials and Methods: Forty-five male Wistar rats were randomly divided into three groups namely the control group (no medication), saline and fluoxetine dissolved in saline. In all groups, nickel titanium closed-coil spring was used between the left maxillary central incisor and first molar to exert 60g force at 2mm activation. Radiographs were taken at one and 21 days. After 21 days, the rats were sacrificed. The distance between the first and second molar teeth, optical density of bone, periodontal ligament (PDL) width, lacuna length and depth and number of osteoclasts were measured and compared among the groups. Results: Tooth movement significantly increased in the fluoxetine group (P=0.005). No significant differences were found in osteoclast count (P=0.069). The PDL width in the mesioapical region of root was significantly different among the groups (P=0.015). Statistical analysis did not show significant differences in depth or length of lacunae in any examined part of the root (P>0.05). Bone densitometry results showed that in fluoxetine group, density of bone in all four areas (alveolar bone, hard palate, skull and mandibular bone) significantly decreased from day one to day 21 (P< 0.05). Conclusion: This study indicated that fluoxetine decreased bone density, which resulted in subsequently greater tooth movement in rats; however, further studies are needed on humans

Effect of Long-Term Captopril Administration on Bone Density and Orthodontic Tooth Movement

Background and Aim: Captopril is an oral angiotensin-converting-enzyme (ACE) inhibitor extensively used in the treatment of hypertension and heart failure. ACE has been suggested to function in bone cells and might therefore impact orthodontic tooth movement (OTM). Considering the controversy surrounding the effects of ACE and its inhibitors on osseous tissues, we aimed to evaluate the effect of captopril on OTM for the first time in a rat model. Materials and Methods: Orthodontic appliances were fixed between the left first molars and incisors of 30 rats divided into three groups (n=10) receiving captopril, saline or no treatment. Following sacrifice on day 21, the amount of tooth movement was measured as the distance created between the first and second molars. Bone density was assessed by lateral cephalograms on days 1 and 21 and osteoclast number, root resorption and periodontal ligament (PDL) width were analyzed histologically. One-way ANOVA followed by post-hoc test were used for statistical analysis (P<0.05) Results: OTM significantly increased in the captopril group compared to the saline and no-treatment groups (P<0.05). Bone density significantly decreased in the mandible of the captopril group from day 1 to 21 (P<0.05). No significant differences were found in the histological variables except for the significant increase in PDL width at the mesioapical aspect in the captopril group. Conclusion: The present study showed that captopril administration could lead to increased OTM and decreased bone density in rats. Further studies are suggested to clarify its exact role at the cellular and molecular levels. Key Words: Captopril, Tooth Movement Techniques, Rat