Bone mineral density in cone beam computed tomography: Only a few shades of gray

Evaluation of the Effects of Photobiomodulation on Bone Density After Placing Dental Implants: A Pilot Study Using Cone Beam CT Analysis

Background: One of the parameters of maximum interest regarding the quality of the intraoral hard tissues is represented by the bone density, with direct clinical implications. The evaluation of this extremely important clinical parameter can be achieved by several imaging methods, of which the most known in dentistry is represented by the cone beam computed tomography (CBCT). Objectives: The purpose of the study is to obtain a quantitative analysis of bone mineral density changes in patients who underwent treatments of photobiomodulation (PBM), as complementary to a surgical approach in oral surgery and implantology. Methods: The study included the retrospective analysis of maxillary cone beam computed tomography of 28 patients without pathology or medication known to affect bone metabolism or its qualitative and quantitative properties. All patients from the study group followed the same laser PBM treatment protocol after placing dental implants; the PBM protocol implied the intraoral use of a gallium aluminum arsenide laser (GaAlAs) of 808 nm, 450 mW, in pulsed mode, administering an energy of 6 J in 3 points corresponding to each inserted dental implant-mesial, distal, and apical-totaling 18 J/implant. Treatment sessions were performed immediately postoperatively and at a subsequent distance of 48 h for 2 weeks (a total of eight sessions). For every patient, bone density was analyzed before and after PBM treatment, in the same areas of interest, within the same anatomical landmarks. A comparison was also made between the results obtained for the anterior maxilla and the posterior maxilla. All the measurements made were analyzed statistically, the results being presented in the dedicated section. Results: Based on the data analysis, the comparison between the lasered and non-lasered groups reveals that patients who underwent PBM showed a statistically significant improvement in bone mineral density, with the mean increasing from 530.91 HU before treatment to 842.55 HU after treatment (t-test: p < 0.001). In contrast, the non-lasered group showed no significant improvement, with a slight decrease in bone mineral density, as the mean dropped from 495.19 HU before treatment to 462.16 HU after treatment (t-test: p = 0.47). Conclusions: The study demonstrated results with statistical significance regarding the mineral bone density improvement of patients who underwent laser PBM treatment. This positive effect of laser therapy has been shown, both at the level of the vestibular cortical bone and at level of the trabecular bone, independent of the patient's sex, for the anterior maxilla and at the lateral areas also.

Predictive Evaluation of Septal Cartilage-bone Complex for Rhinoplasty Using Cone Beam Computed Tomography

Background

Septal extension grafting (SEG) is commonly used for correcting Asian short noses. When septal cartilage is limited, septal bone can be included. This study evaluates the outcomes of SEG using a septal cartilage-septal bone complex (SCBC) and assesses preoperative cone beam computed tomography (CBCT) for predicting septal bone suitability.

Methods

A retrospective review was conducted of Korean women planned for SEG with SCBC from July 2021 to June 2022. Preoperative CBCT scans measured Hounsfield Unit (HU) values for septal cartilage, perpendicular plate of the ethmoid (PPE), and vomer. Of 27 patients, 19 underwent SEG with SCBC, whereas 8 did not due to unsuitable septal bone. Clinical outcomes and satisfaction were assessed through surveys and photographs.

Results

For the 19 patients using SCBC, the average HU for PPE was 286.5 ± 126.6 (ratio 6.8 ± 2.1), and for vomer, HU was 230.3 ± 95.2 (ratio 5.7 ± 1.8). SEG significantly improved nasal length and tip projection, although tip softness was less favorable. Among the 8 patients not using SCBC, 5 had bones that were too thick and stiff (PPE: 667.8 ± 102.2, ratio 15.5 ± 2.7; vomer: 342.8 ± 55.1, ratio 8.1 ± 2.3), and 3 had fragile bones (PPE: 148.7 ± 45.4, ratio 3.1 ± 0.7; vomer: 199.0 ± 68.6, ratio 4.1 ± 0.9).

Conclusions

SEG using SCBC effectively corrects short noses in Asian patients. Preoperative HU ratios from CBCT can help predict septal bone quality and guide surgical planning. Further research with larger cohorts is needed to confirm these findings.

3D Analysis of Tooth Movement Using 3D Technology

PURPOSE OF REVIEW

3D cone beam imaging (CBCT) has allowed clinicians to better understand the anatomical variations of cranial anatomy. One crucial aspect of this technology plays is the understanding of alveolar bone morphology and remodeling. Variations in cortical bone thickness between individuals have been reported. No published study has analyzed the relationship between cortical bone thickness and rate of tooth movement. The aim of this study is to begin answering the question: is there an association between rate of tooth movement and cortical bone thickness?

RECENT FINDINGS

Twenty-three patients underwent extraction of a single premolar in each of the four quadrants prior to orthodontic therapy. Routine clinical records including 3D CBCT images were acquired of all patients prior to first premolar extractions. Rate of tooth movement in each quadrant for each patient was determined via mesiodistal millimetric measurements obtained by a single calibrated operator. With CBCT images, cortical bone thickness was measured at various levels from the alveolar crest along the long axis of the to-be-extracted first premolars. The association between cortical bone thickness and rate of tooth movement was analyzed. Statistically significant associations were found between rate of tooth movement and cortical bone thickness at levels 2 mm, 5 mm, and 8 mm, apical to the alveolar crest in both the right and left maxillary quadrants (p < 0.05). Statistically significant associations were found between rate of tooth movement and cortical bone thickness at levels 5 mm and 8 mm apical to the alveolar crest in both mandibular quadrants (p < 0.05). Increased cortical bone thickness was associated with decreased rate of tooth movement. There was no statistically significant association between rate of tooth movement and cortical bone thickness 2 mm apical to the alveolar crest of the to-be-extracted first premolars in the mandibular left nor right quadrants (p > 0.05). Results suggest an inverse relationship may exist between cortical bone thickness and rate of tooth movement in both the maxilla and mandible. Cortical bone thickness may have the potential to serve as a predictive tool for rate of orthodontic tooth movement.

Outcomes of Xenograft with Platelet-rich Fibrin versus Autogenous Bone in Alveolar Cleft Grafting

Background

The use of a suitable graft material helps with sufficient osseointegration. The aim of this study was to compare the clinical and radiographic outcomes of two types of alveolar bone graft materials, xenografts with platelet-rich fibrin (PRF) and autogenous grafts, in patients with alveolar clefts.

Methods

Thirty-six patients with alveolar clefts were enrolled in this study. Those patients were randomly divided into two groups: group A, where the autogenous iliac bone graft was used to fill the alveolar defect, and group B, where the xenograft with PRF was used to fill the alveolar defect. After 6 months of grafting, patients were assessed in terms of pain, duration of hospital stay, and donor site morbidity associated with iliac crest harvesting, while bone formation was evaluated radiographically using cone beam computed tomography.

Results

The results showed no statistical differences as regards baseline and perioperative data. Operative duration was significantly lower among xenograft with PRF patients. Both groups had comparable postoperative success scores, and total failure was reported in a total of three patients (one patient in group A and two patients in group B).

Conclusions

With no potential donor site morbidities, xenograft with PRF is an equivalent bone transplant replacement to the autologous iliac bone graft. Additionally, it is associated with a significant success rate, and a significant decrease in operative time and hospital stay. Many future studies are warranted to draw firm conclusions.

A comparative radiographic study of bone density changes around titanium implants in the posterior mandible, preoperative, and postoperative

Background

Implant success and the state of the surrounding bone require multiple measures, especially in humans, and this study aimed to identify the development of the state of the latter by means of radiographic examination performed during the period of osseointegration as well as investigate the changes in bone density that occur after implant installation and 2 months after functional loading. Implant success rates are affected by bone density at the implant site. Therefore, understanding changes in bone density after dental implant placement is essential, as it correlates with subsequent implant success.

Materials and methods

Digital radiographs of 28 implants were taken and evaluated at four intervals: preoperatively, 1 and 3 months postoperatively, and 2 months following placement of the permanent prosthesis. Gray values were measured in different areas around the implants through analyzing X-ray images and measuring bone density around the implants using EzDent - 2D software. The aim of this study was to investigate changes in bone density around implants in three regions: apex, neck, and body, as well as to record average density values during the observation period by measuring digital image gray levels (the gray values of the digital radiographs). This was conducted to determine local bone densities in dental implant recipient sites and to study changes in local bone densities at different intervals, preoperatively and postoperatively and after placement of the prosthesis.

Results

A decrease was observed in gray values proportional to reference values 1-month after implant insertion, but these increased at 3 months after insertion and continued to rise 2 months after placement of the prosthesis in the apical, body, and neck regions of the implant.

Conclusion

Sensor-tuned radiography can be used as an effective method to support clinical follow-ups as well as measure changes in bone densities around implants in critical cases.

Assessment of CBCT gray value in different regions-of-interest and fields-of-view compared to Hounsfield unit

OBJECTIVES

Different factors can affect the discrepancy between the gray value (GV) measurements obtained from CBCT and the Hounsfield unit (HU) derived from multidetector CT (MDCT), which is considered the gold-standard density scale. This study aimed to explore the impact of region of interest (ROI) location and field of view (FOV) size on the difference between these two scales as a potential source of error.

METHODS

Three phantoms, each consisting of a water-filled plastic bin containing a dry dentate human skull, were prepared. CBCT scans were conducted using the NewTom VGi evo system, while MDCT scans were performed using Philips system. Three different FOV sizes (8 × 8 cm, 8 × 12 cm, and 12 × 15 cm) were used, and the GVs obtained from eight distinct ROIs were compared with the HUs from the MDCT scans. The ROIs included dental and bony regions within the anterior and posterior areas of both jaws. Statistical analyses were performed using SPSS v. 26.

RESULTS

The GVs derived from CBCT images were significantly influenced by both ROI location and FOV size (p < 0.05 for both factors). Following the comparison between GVs and HUs, the anterior mandibular bone ROI represented the minimum error, while the posterior mandibular teeth exhibited the maximum error. Moreover, the 8 × 8 cm and 12 × 15 cm FOVs resulted in the lowest and highest degrees of GV error, respectively.

CONCLUSIONS

The ROI location and the FOV size can significantly affect the GVs obtained from CBCT images. It is not recommended to use the GV scale within the posterior mandibular teeth region due to the potential for error. Additionally, selecting smaller FOV sizes, such as 8 × 8 cm, can provide GVs closer to the gold-standard numbers.

Correlation among alveolar bone assessments provided by CBCT, micro-CT, and 14 T MRI

Objectives:

The aim of this study was to evaluate bone mineral adipose tissue (BMAT) volume in 21 alveolar bone specimens, as determined by 14 T magnetic resonance imaging (MRI), and correlate them to the radiodensity values obtained preoperatively of regions of interest by cone beam computed tomography (CBCT), and to the BV/TV ratio values obtained by micro-CT, the gold-standard for morphometric data collection.

Methods:

Partially edentulous patients were submitted to a CBCT scan, and the radiographic bone densities in each ROI were automatically calculated using coDiagnostiX software. Based on the CBCT surgical planning, a CAD/CAM stereolithographic surgical guide was fabricated to retrieve a bone biopsy from the same ROIs scanned preoperatively, and then to orientate the subsequent implant placement. The alveolar bone biopsies were then collected and scanned using the micro-CT and 14 T MRI techniques. Pearson’s correlation test was performed to correlate the results obtained using the three different techniques.

Results:

In the 21 eligible bone specimens (6 females, 15 males), age (mean age 52.9 years), micro-CT, and 14 T MRI variables were found to be normally distributed (p > 0.05). The strongest—and only statistically significant (p < 0.05)—correlation was found between micro-CT and 14 T MRI values (r = 0.943), and the weakest, between 14 T MRI and CBCT values (r = –0.068).

Conclusions:

The findings suggest that 14 T MRI can be used to evaluate BMAT as an indirect marker for bone volume, and that CBCT is not a reliable technique to provide accurate bone density values.

A Comparative Study on the Voxel Values in Alveolar Bones Acquired by MDCT and Newly Developed Dental Dual-Energy CBCT

The purpose of this study was to analyze the effectiveness of newly developed dental dual-energy (DE) cone-beam computed tomography (CBCT) to compare both the voxel values in hard bone tissue of DE-CBCT and multidetector computed tomography (MDCT) images, collected in a clinical trial conducted at Seoul National University Dental Hospital. A software implemented as a scripted module of a three-dimensional (3D) slicer was developed to register the volume data from the MDCT space to DE-CBCT, locate the same 3D regions of interest (ROIs) in each image space, and extract the statistics of the ROIs. The mean values were paired and used as representative values of the ROIs. A scatter plot with the line of equality and Bland–Altman (BA) plot of difference for a pair of measured means were used for statistical analysis. Of the ROI pairs, 96% were within ±15% from the identity line, and more than 95% of the measured ROI pairs were within the limits of agreement of the 95% confidence intervals (CIs), with the CI of the limits in BA plots. The newly developed dental DE-CBCT showed a level of voxel value accuracy similar to that of MDCT.

Gray value measurement for the evaluation of local alveolar bone density around impacted maxillary canine teeth using cone beam computed tomography

Background

To investigate whether any relationship between local alveolar bone density and maxillary canine impaction using gray values from cone beam computed tomography.

Material and Methods

The cone beam computed tomography images of 151 patients were retrospectively evaluated. Maxillary canine was defined as an impacted tooth when root formation was complete and the patient’s age older than 13 or the other side of the maxillary canine has completely erupted. Similarly, complete eruption was defined as the tooth in its expected occlusion and position. Using the cone beam computed tomography software, the region of interest which was 5 mm2 in area, was placed in the trabecular bone on cross sectional cone beam computed tomography images and the gray value measurements were recorded. After measuring the gray values of all the teeth, the images were grouped according to the field of view size. Comparison of the gray values of impacted and non-impacted teeth was made between images with the same field of view size.

Results

A total of 151 patients, 101 (66.9%) female and 50 (33.1%) male, were included in the study. The mean age of the patients was 24.94 ±13.9. In images with a 40X40 field of view, the gray values of the impacted canine teeth were higher than the gray values of the non-impacted ones and statistically significant difference was found between them (p=0.003). However no statistically significant difference was found between the gray values of impacted and non-impacted canine teeth in 60x60 and 100x50 field of view (p=0.197, p=0.170, respectively).

Conclusions

We suggest using the smallest field of view size when evaluating bone density using gray values from cone beam computed tomography images and we support the idea that the local increased bone density may influence on impaction.

Key words:Cone-beam computed tomography, tooth, impacted, bone density, maxilla, image processing, computer-assisted.

Associations among Primary Stability, Histomorphometric Findings, and Bone Density: A Prospective Randomized Study after Alveolar Ridge Preservation with a Collagen Cone

BACKGROUND

The objective of this investigation was to examine whether determination of bone density (BD) with a cone beam computed tomography (CBCT) scan could help predict the primary stability (PS) of the implants and to investigate whether associations between the histomorphometric findings and the CBCT scan could be observed.

MATERIALS AND METHODS

In this randomized clinical study, the efficacy of alveolar ridge preservation (ARP) with a combination of a collagen cone and a collagen membrane procedure after tooth extraction was investigated. CBCT scans were obtained after a healing period of 8 (±1) weeks. Subsequently, the CBCT scans were evaluated in terms of BD at different heights of the former socket. Eleven (±1) weeks after tooth extraction, implant placement was performed and PS was measured with resonance frequency analysis. Potential associations among the radiologically measured BD, the histomorphometric results, and the PS were analyzed.

RESULTS

No direct association was observed between the radiologically determined BD and the histomorphometric findings. No significant associations could be found between the BD and the PS.

CONCLUSION

No significant associations were observed among the BD determined by the CBCT, the histomorphometric findings, and the PS.

Pixel gray measurement for the diagnosis of dental ankylosis in cone beam computed tomography images

OBJECTIVE

The aim of this study was to investigate dental ankylosis in unerupted or partially erupted teeth by using cone beam computed tomography (CBCT) to quantify pixel intensity.

STUDY DESIGN

In total, 157 CBCT images from individuals with a total of 206 unerupted or partially erupted teeth with suspected ankylosis were evaluated. CBCT images were analyzed for the presence of ankylosis by 2 oral radiologists by quantifying mean pixel intensities (analysis 1) and variations in pixel intensities (analysis 2) in normal and ankylosed regions. The association between ankylosis and demographic and tooth-related factors was also examined.

RESULTS

Ankylosis was diagnosed in 57 teeth (27.7%). The diagnosis was established with all 3 multiplanar reconstruction views in 22 of these teeth (38.6%). In analysis 1, a higher pixel intensity was observed in areas with ankylosis compared with normal periodontal ligament (PDL) density as a result of bone deposition in this region, which is characteristic of ankylosis (P < .001). In analysis 2, reductions in pixel intensity were greater in the PDL areas than in the ankylosed areas. Ankylosis was significantly associated with the anterior teeth, the maxillary arch, single-rooted teeth, and impacted teeth (P ≤ .026).

CONCLUSIONS

Our results suggest that CBCT measurement of pixel intensity may be useful for the diagnosis of ankylosis.

Standardization of a cone beam computed tomography machine in evaluating bone density: a novel approach

BACKGROUND

Advent of cone beam computed tomography (CBCT) in dentistry has brought us to a new era of precise imaging. Radiographic evaluation of a CBCT image is more informational when compared to CT. The density measurements in CBCT images are based on greyscale values, which are more accurate in CT and these values are inconsistent across various CBCT machines. Hence, we aim at standardizing a single CBCT scanner to evaluate or determine tissue density from the greyscale values.

METHODS

A total of 8 halves of undamaged, dry goat mandibles are included in the study. Scans of the bone are obtained using the KODAK CBCT unit and the PHILLIPS CT machine respectively. Densities are evaluated at 96 points on both the CT scans and the CBCT scans, respectively, using the Radiant Dicom viewer. The obtained data is entered into the excel spreadsheet and subjected to statistical analysis.

RESULTS

The greyscale values are obtained from each of the CBCT scans. Hounsfield units are calculated from CT images coinciding with the same points on CBCT scans. The collected data is subjected to linear regression analysis and an equation is derived to determine Hounsfield units (calculated HU units) from greyscale values of CBCT images. We found no significant difference between the mean original HU units and the mean calculated HU units, thus making the equation reliable for calculating HU units from CBCT greyscale values.

CONCLUSIONS

Our results conclude that the technique was effective in calculating the Original density of tissues using grey standards of CBCT scans.

Interspecies Comparison of Alveolar Bone Biology, Part I: Morphology and Physiology of Pristine Bone

INTRODUCTION

Few interspecies comparisons of alveolar bone have been documented, and this knowledge gap raises questions about which animal models most accurately represent human dental conditions or responses to surgical interventions.

OBJECTIVES

The objective of this study was to employ state-of-the-art quantitative metrics to directly assess and compare the structural and functional characteristics of alveolar bone among humans, mini pigs, rats, and mice.

METHODS

The same anatomic location (i.e., the posterior maxillae) was analyzed in all species via micro-computed tomographic imaging, followed by quantitative analyses, coupled with histology and immunohistochemistry. Bone remodeling was evaluated with alkaline phosphatase activity and tartrate-resistant acid phosphatase staining to identify osteoblast and osteoclast activities. In vivo fluorochrome labeling was used as a means to assess mineral apposition rates.

RESULTS

Collectively, these analyses demonstrated that bone volume differed among the species, while bone mineral density was equal. All species showed a similar density of alveolar osteocytes, with a highly conserved pattern of collagen organization. Collagen maturation was equal among mouse, rat, and mini pig. Bone remodeling was a shared feature among the species, with morphologically indistinguishable hemiosteonal appearances, osteocytic perilacunar remodeling, and similar mineral apposition rates in alveolar bone.

CONCLUSIONS

Our analyses demonstrated equivalencies among the 4 species in a plurality of the biological features of alveolar bone. Despite contradictory results from older studies, we found no evidence for the superiority of pig models over rodent models in representing human bone biology.

KNOWLEDGE TRANSFER STATEMENT

Animal models are extensively used to evaluate bone tissue engineering strategies, yet there are few state-of-the-art studies that rigorously compare and quantify the factors influencing selection of a given animal model. Consequently, there is an urgent need to assess preclinical animal models for their predictive value to dental research. Our article addresses this knowledge gap and, in doing so, provides a foundation for more effective standardization among animal models commonly used in dentistry.

Evaluating mandibular symphysis bone density according to various skeletal patterns with CBCT

OBJECTIVE

The aim of this retrospective study was to evaluate the bone density (BD) at the mandibular symphysis according to horizontal and vertical patterns using cone-beam computed tomography (CBCT).

SETTING AND SAMPLING

Three hundred nineteen untreated adults with a mean age of 24 years.

MATERIALS AND METHODS

CBCT images were converted into the lateral cephalometric images, and tracings were performed for categorizing the patients based on skeletal features. Cortical BDs at B point, pogonion (Pog), genion (Ge) and menton (Me), and cancellous BDs of the mandibular symphysis were measured using CBCT images. Statistical analyses were performed to evaluate the effects of horizontal and vertical skeletal patterns on BDs.

RESULTS

Females exhibited higher BD than males at the Me, Pog, Ge (P < .001). Hyperdivergent skeletal pattern showed significantly higher cortical BD than normovergent and hypodivergent skeletal patterns at Me (P < .001). Normovergent skeletal pattern showed significantly higher cortical BD than hypodivergent skeletal patterns at Me (P = .001). Class II skeletal pattern showed significantly higher cortical BD than Class I and III skeletal patterns at Me (P < .001) and Ge (P < .05). Class I skeletal pattern showed significantly higher mean cortical BD than Class III skeletal pattern at B point (P = .025). Cancellous BD was higher in Class III and hypodivergent skeletal patterns than others but showed no statistical significance.

CONCLUSIONS

Significant differences were identified across various skeletal patterns. Several mandibular symphyseal landmarks showed statistically significant differences in BD at Me, B point and Ge, with Me having the most statistically significant findings.

CT Role in the Assessment of Existence of Breast Cancerous Cells

BACKGROUND

Application of CT- scanning image information and radiation physical characteristics of the biomaterials are two measurable assays for presenting modified cells.

OBJECTIVE

This study presented that CT number (HU) and linear attenuation coefficient contain useful information which can be determined during usual CT scanning for the prediction of breast cancerous cells existence based on hemoglobin concentration.

MATERIAL AND METHODS

This experimental study used breast phantom containing major and minor vessels with diameters of 10 and 5 mm, respectively. The major vessels are filled by water, fat, hemoglobin (Hb) as a normal and 4× concentration of hemoglobin (4×Hb) as a cancerous breast cells, then scanned by single slice CT (GE, Hi Speed) 120 kVp, 100 mA for the determination of linear attenuation coefficient (μ_L ).

RESULTS

The CT numbers were for water (-7 to +7 HU), Hb (22±6 HU) and 4×Hb (80±4 HU). The difference between Hb and 4×Hb was significant (p <0.000). Minimum μ_L was 0.1190±0.00680 cm^-1 for fat and maximum was 0.1449±0.00794 cm^-1 for 4×Hb.

CONCLUSION

The study of CT number and linear attenuation coefficient of different concentration of Hb provides a possibility for early predicting of breast cancerous cells existence (4×Hb).

A clinical pilot study of jawbone mineral density measured by the newly developed dual-energy cone-beam computed tomography method compared to calibrated multislice computed tomography

Purpose

This clinical pilot study was performed to determine the effectiveness of dual-energy cone-beam computed tomography (DE-CBCT) in measuring bone mineral density (BMD).

Materials and Methods

The BMD values obtained using DE-CBCT were compared to those obtained using calibrated multislice computed tomography (MSCT). After BMD calibration with specially designed phantoms, both DE-CBCT and MSCT scanning were performed in 15 adult dental patients. Three-dimensional (3D) Digital Imaging and Communications in Medicine data were imported into a dental software program, and the defined regions of interest (ROIs) on the 3-dimensional surface-rendered images were identified. The automatically-measured BMD values of the ROIs (g/cm³), the differences in the measured BMD values of the matched ROIs obtained by DE-CBCT and MSCT 3D images, and the correlation between the BMD values obtained by the 2 devices were statistically analyzed.

Results

The mean BMD values of the ROIs for the 15 patients as assessed using DE-CBCT and MSCT were 1.09±0.07 g/cm³ and 1.13±0.08 g/cm³, respectively. The mean of the differences between the BMD values of the matched ROIs as assessed using DE-CBCT and calibrated MSCT images was 0.04±0.02 g/cm³. The Pearson correlation coefficient between the BMD values of DE-CBCT and MSCT images was 0.982 (r=0.982, P<0.001).

Conclusion

The newly developed DE-CBCT technique could be used to measure jaw BMD in dentistry and may soon replace MSCT, which is expensive and requires special facilities.

Comparison of mandibular cortical bone among obese, overweight, and normal weight adolescents using panoramic mandibular index and mental index

OBJECTIVE

The objective of this study is to evaluate the mental index (MI) and panoramic mandibular index (PMI) of a group of adolescent patients in different body mass index (BMI) percentile.

MATERIAL AND METHODS

Subjects were divided into three different groups in accordance to their BMI percentile status: normal weight (35 subjects; mean age, 14.81 ± 2.12 years), overweight (32 subjects; mean age, 14.77 ± 2.56 years), and obese (33 subjects; mean age, 14.06 ± 2.59 years) groups. Mental index (MI) and panoramic mandibular index (PMI) were assessed on panoramic radiographs.

RESULTS

There were statistically significant differences in PMI and MI that were observed among groups (p < 0.0001 and p < 0.001, respectivel). MI and PMI are higher in overweight and obese individuals than in normal-weight.

CONCLUSIONS

Mandibular cortex was found thicker in patients who are obese and overweight compared to normal weight patients. We can suggest that young obese individuals' bone structure can be take in consideration in orthodontic or dental surgical treatment planning.

CLINICAL RELEVANCE

Dense cortical bone may cause some difficulties in orthodontic and surgical treatment. Clinicians should understand obesity and overweight-related jaw bone changes and consider these factors to treat their patients.

Assessment of the Capability of Bone Density Contrast Dissociation in Cone Beam Computed Tomography Compared to Digital Periapical Radiography by Using a Phantom

STATEMENT OF THE PROBLEM

Assessment of bone density changes plays an important role in diagnosis, treatment, and follow-up procedures. The feasibility of cone-beam computed tomography (CBCT) for assessment of bone density changes is still controversial.

PURPOSE

The aim of this study was to investigate the capability of bone density contrast dissociation of CBCT compared to digital periapical radiography.

MATERIALS AND METHOD

In this in vitro, experimental study, we designed radiographic phantom for bone density simulation. The phantom was a polytetrafluoroethylene rectangular cube with five-chambers. Five micro-tubes (2 mL) containing different concentrations of dipotassium phosphate (K₂HPO₄) were placed within these chambers. Different concentrations of K₂HPO₄ were scanned by CBCT; the mean voxel value of each micro-tube was measured and compared with the concentration of K₂HPO₄ that represented bone density.

RESULTS

CBCT results showed that there were no significant correlations between 300 mg/mL and lower concentrations of K₂HPO₄ and CBCT voxel values (P≤0.52) but there was a significant correlation between concentrations of K₂HPO₄ higher than 300 mg/mL and CBCT voxel values (p< 0.001).

CONCLUSION

CBCT is a reliable method for the assessment of bone density changes in the high range of bone density but it is not reliable for such assessment in the lower range of bone density. Digital periapical imaging method may not be applied for the assessment of bone density, whereas in higher densities, the employment of CBCT seems to be feasible.

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.

Reproducibility of CBCT image analysis: a clinical study on intrapersonal and interpersonal errors in bone structure determination

OBJECTIVE

For correct implant planning based on cone-beam computed tomography (CBCT), the bone contour must be accurately determined. Identification of the contour is difficult in bones with incomplete mineralization. In this clinical study, we investigated the intrapersonal and interpersonal reproducibilities of manual bone contour determination on CBCT images using a semi-automated computerized process.

METHODS

The bone surface level in the area of the socket in 20 patients who had undergone tooth extraction from the upper jaw at 10 ± 1 weeks previously was determined on CBCT images. Two investigators with different levels of experience determined the bone structure initially (T₀) and repeated the procedure after 3 months (T₁). The bone structure marked on CBCT images was converted into a surface data set. The resulting data sets were superimposed on one another. In the analyses, the shortest distances between the datasets were identified and measured. The average deviations were statistically evaluated.

RESULTS

The intrapersonal evaluation resulted in an average deviation of 0.18 mm across both investigators. The interpersonal analysis comparing the two investigators resulted in average deviations of 0.15 mm at T₀ and 0.26 mm at T₁. Significant differences were not found.

CONCLUSIONS

The low intrapersonal deviation indicates that the procedure has satisfactory reproducibility. All deviations were within the range of the selected resolution of the CBCT device. Application of a semi-automated procedure to detect the bone border in areas with incomplete mineralization is a predictable process.

TRIAL REGISTRATION

The study was registered in the German Clinical Trials Register and the International Clinical Trials Registry Platform of the WHO: DRKS00004769, date of registration: 28 February 2013; and DRKS00005978, date of registration: 09 November 2015.

Gender and growth variation in palatal bone thickness and density for mini-implant placement

BACKGROUND

The objective was to compare the palatal bone thickness (PBT) and palatal bone density (PBD) in the anterior, middle, and posterior part of the palate in males and females.

METHODS

This retrospective study reviewed cone beam computed tomography scans of 359 patients. The scans were divided into 99 growing males, 105 growing females, 74 non-growing males, and 81 non-growing females. The measurements of PBT and PBD were made in between the canine and first premolar, the first premolar and second premolar, the second premolar and first molar, and the first molar and second molar. The measurements were made in the center of the palate and 4 mm away from the center. ANOVA was used to analyze the PBT and PBD in different areas between four different groups.

RESULTS

The PBT was lower (P <  0.0001) as we moved from the anterior to the posterior palate. The PBT was more (P <  0.001) in the center of the palate than 4 mm away from the center, except in between the canine and first premolar. The growing male and non-growing male had higher (P <  0.0001) PBT than the growing female and non-growing female in between the canine and first premolar and the first premolar and second premolar both in the center and 4 mm away from it. The PBD was higher (P <  0.05) in between the canine and first premolar area at the center of the palate and between the second premolar and first molar 4 mm away from the center in all the experimental groups.

CONCLUSIONS

There exists a definite gender and growth variation in the PBT and PBD in different parts of the palate. Palatal bone thickness between the males and females revealed that the males had significantly higher PBT than the females.

Investigation of dental cone-beam CT pixel data and a modified method for conversion to Hounsfield unit (HU)

OBJECTIVES

To investigate the relationship in dental cone-beam CT (CBCT) between the manufacturer-reported image pixel data and a modified conversion to CT number densities in Hounsfield unit (HU).

METHODS

A standardized CT phantom was imaged using typical clinical parameters on CBCT from three manufacturers (Carestream 9300^®, Carestream Health, Rochester, NY; J Morita 3D Accutomo^®, J. Morita Mfg. Corp., Kyoto, Japan; and Planmeca Promax 3D^®, Planmeca Helsinki, OY, Finland). Reconstructed axial slices were evaluated using regions of interest to ascertain the mean pixel value in five materials in the phantom. The Digital Imaging and Communications in Medicine data were also evaluated to determine if raw pixel data had been adjusted during the image reconstruction. A modified version of the existing manual HU conversion technique was applied, and the resultant slope and y-intercept were used to scale the pixel values ultimately to HU for all images.

RESULTS

The DICOM header data show that a modified rescale y-intercept was applied to both the Carestream and Planmeca image data yielding manufacturer-produced results in HU. The Morita pixel data were unmodified and report in shades of grey or grey values (GV). The Carestream manufacturer-derived HU measurements showed good correlation in air (-1000 HU), but all other materials ranged from 2.6 to 13.5 σ from the specified phantom value. Results in the modified conversion technique images fell within 1.0-2.4 σ from the specified phantom values.

CONCLUSIONS

While more studies are needed to test for regularity, this study suggests that our modified technique could be a means of getting more accurate quantitative data from dental CBCTs.

Radiolucency in stemless shoulder arthroplasty is associated with an imaging phenomenon

Stemless humeral implants show comparable midterm clinical results compared to stemmed components. Recently, radiolucencies around the metaphyseal seating of humeral stemless implants were reported on postoperative radiographs. It is controversial whether they are attributable to bone resorption. We hypothesized these radiolucencies result from imaging artifacts. Seven cadaveric specimens (three male and four female) were first radiographed and then scanned with CT. A stemless humeral component of current design was implanted in each specimen. After implantation, all specimens were radiographed with different exposure settings. The implant was removed, and the specimens were scanned with CT again. Pre- and post-implantation radiographs and CT scans were compared. The mean Hounsfield units (HU) at the humeral resection plane from the pre-implantation CT were correlated with the diameter of the radiolucent halo on the post-implantation radiographs. A symmetric radiolucent halo of variable diameters occurred on all radiographs after implantation when an automatic exposure control was used. The halo disappeared in all specimens when the tube voltage was reduced. Lower CT-values (HU) before the implantation resulted in greater halos on the radiograph after implantation. Symmetric radiolucent halos can result from imaging artifacts, which is most likely due to radiation scatter. The halos can be minimized by reducing the tube voltage. The halo effect appears to be pronounced in bones with decreased density. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2040-2050, 2017.

Effects of different loading protocols on the secondary stability and peri-implant bone density of the single implants in the posterior maxilla

BACKGROUND

Immediate or early loading of dental implants becomes a clinically feasible concept.

PURPOSE

The aim was to evaluate the effects of different loading protocols (immediate, early, and delayed) on secondary stability and peri-implant bone density of single implants in the posterior maxilla.

MATERIALS AND METHODS

Thirty-nine implants (Dentium, South-Korea) were placed in 39 patients. After placement, implant stability values (ISQ) and baseline peri-implant bone density values derived from cone-beam computed tomography were recorded. Thirteen implants were included randomly in each loading groups. The secondary ISQ values were recorded during follow-up visits. Peri-implant bone density values were measured 1 year after placement again. Data was statistically analyzed.

RESULTS

Immediate-loaded group showed the lowest ISQ values, 1 month after placement. During the next follow-up visits, delayed-loaded group showed the lowest ISQ values while other groups showed comparable results. Early loading increased the peri-implant bone density greater than the other groups.

CONCLUSIONS

The peri-implant bone of early-loaded implants was significantly denser than that of immediate- and delayed-loaded implants, 1 year after placement. Density increment can be judged as the radiological findings of loaded-bone, which may also reduce the need for histomorphometric analysis of human biopsy to evaluate the bone reaction around the implants.

Morphological characteristics of cartilage-bone transitional structures in the human knee joint and CAD design of an osteochondral scaffold

Background

There is a lack of understanding of the morphological characteristics of the cartilage-bone interface. Materials that are currently being used in tissue engineering do not adequately support the regeneration of bone and cartilage tissues. The present study aimed to explore the morphological characteristics of cartilage-bone transitional structures in the human knee joint and to design a biomimetic osteochondral scaffold based on morphological data.

Methods

Histology, micro-computed tomography (micro-CT), and scanning electron microscopy (SEM) were used to investigate the microstructure of the cartilage-bone transitional structures. Morphological characteristics and their distribution were obtained and summarized into a biomimetic design. A three-dimensional model of a biomimetic osteochondral scaffold was CAD designed. A prototype of the resulting subchondral bone scaffold was constructed by stereolithography using resin.

Results

Micro-CT revealed that subchondral bone presented a gradually changing structure from the subchondral to spongy bone tissue. The subchondral bone plate was more compact with ~20 % porosity compared with ~60 % porosity for the spongy bone. Histology and SEM showed that cartilage was stabilized on the subchondral bone plate by conjunctions, imbedding, interlocking, and binding forces generated by collagen fibers. Some scattered defects allow blood vessel invasion and nutritional supply.

Conclusions

The subchondral bone plate is not an intact plate between the cartilage and bone cavity, and some scattered defects exist that allow blood vessel invasion and nutritional supply. This characteristic was used to design an osteochondral scaffold. This could be used to construct an osteochondral complex that is similar to native bones.

Bone density effects on the success rate of orthodontic microimplants evaluated with cone-beam computed tomography

INTRODUCTION

The purpose of this study was to evaluate the effect of bone densities on the success rate of orthodontic microimplants with cone-beam computed tomography images.

METHODS

We examined 127 orthodontic microimplants implanted into the maxillary buccal alveolar bone of 71 patients (53 female, 18 male; mean age, 19.2 years) with malocclusion. The cortical, cancellous, and total bone densities were measured with Simplant Pro 2011 software (version 13; Materialise, Leuven, Belgium), and the correlations between these measurements and the orthodontic microimplant success rates were evaluated with cone-beam computed tomography.

RESULTS

The overall success rate was 85.0% (108 of 127). Sex, age, and side of placement were not significant factors for success in the results (P >0.05). The density of the cortical bone increased apically (3, 5, and 7 mm) from the alveolar crest, but in the cancellous bone it decreased. Whereas the orthodontic microimplant success rates significantly increased as cancellous bone density and total bone density increased (P <0.01), cortical bone density did not have a significant effect on the success rate (P >0.05).

CONCLUSIONS

The success rate of orthodontic microimplants significantly increased with higher cancellous and total bone densities, whereas cortical bone density did not have a significant effect.

The anterior maxilla as a potential source of bone grafts: a morphometric cone beam computed tomography analysis of different anatomical areas

The aim of this research was to use cone beam computed tomography (CBCT) to analyze the volume, density, and morphology of the bone available in the anterior region of the maxilla, in order to investigate its potential as a source of bone grafts. Three independent zones were evaluated: the palatine process of the maxilla (PPM), anterior nasal spine (ANS), and subnasal bone (SN). The latter was analyzed bilaterally (SNR, SNL). One hundred CBCT scans were evaluated. The morphometric analysis comprised volumetric and subsequent automatic density calculations, as well as linear measurements. Potential correlations among these parameters, including demographic characteristics, were investigated. The study comprised 52 women and 48 men (mean age 49.6±14.5 years). The calculated bone volume averaged 2.41±0.72cm(3) for PPM, 0.46±0.16cm(3) for ANS, 0.58±0.2cm(3) for SNR, and 0.57±0.21cm(3) for SNL. The anterior region of the maxilla can provide a considerable amount of bone volume from different anatomical zones and should be regarded as a potential donor site for the regeneration of maxillary atrophic bones. Further investigation is required before these findings can be applied in the routine clinical setting.

Does Orthodontic Treatment Affect the Alveolar Bone Density?

Few studies involving human participants have been conducted to investigate the effect of orthodontic treatment on alveolar bone density around the teeth. Our previous study revealed that patients who received 6 months of active orthodontic treatment exhibited an ∼24% decrease in alveolar bone density around the teeth. However, after an extensive retention period following orthodontic treatment, whether the bone density around the teeth can recover to its original state from before the treatment remains unclear, thus warranting further investigation.The purpose of this study was to assess the bone density changes around the teeth before, during, and after orthodontic treatment.Dental cone-beam computed tomography (CBCT) was used to measure the changes in bone density around 6 teeth in the anterior maxilla (maxilla central incisors, lateral incisors, and canines) of 8 patients before and after orthodontic treatment. Each patient underwent 3 dental CBCT scans: before treatment (T0); at the end of 7 months of active orthodontic treatment (T1); after several months (20-22 months) of retention (T2). The Friedman test was applied to evaluate the changes in the alveolar bone density around the teeth according to the 3 dental CBCT scans.From T0 to T1, a significant reduction in bone density was observed around the teeth (23.36 ± 10.33%); by contrast, a significant increase was observed from T1 to T2 (31.81 ± 23.80%). From the perspective of the overall orthodontic treatment, comparing the T0 and T2 scans revealed that the bone density around the teeth was relatively constant (a reduction of only 0.75 ± 19.85%). The results of the statistical test also confirmed that the difference in bone density between T0 and T2 was nonsignificant.During orthodontic tooth movement, the alveolar bone density around the teeth was reduced. However, after a period of bone recovery, the reduced bone density recovered to its previous state from before the orthodontic treatment. However, the bone density around ∼10% of the teeth in this region could not recover to 80% of its state from before the orthodontic treatment.