Journal of Dental Implants
   About JDI | Editorial | Search | Ahead of print | Current Issue | Archives | Instructions | Subscribe | Login 
Users Online: 666  Wide layoutNarrow layoutFull screen layout Home Print this page  Email this page Small font size Default font size Increase font size


 
 
Table of Contents
ORIGINAL ARTICLE
Year : 2013  |  Volume : 3  |  Issue : 1  |  Page : 16-20

Validation of trabecular bone density profile at potential implant sites as a simple and accurate predictor of bone quality


1 Department of Prosthodontics and Crown and Bridge, J.C.D. Dental College, Sirsa, Haryana, India
2 Department of Dental and Maxillofacial Radiology, DCA Imaging Research Centre, New Delhi, India
3 Consultant Radiologist, Dental and Maxillofacial Diagnostics, Ghaziabad, Uttar Pradesh, India
4 Dr. Lalpath Labs, Indirapuram, India

Date of Web Publication10-May-2013

Correspondence Address:
Ashish Chaturvedi
A-12, Ground Floor, RDC Rajnagar, Ghaziabad - 201 002
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-6781.111674

Rights and Permissions
   Abstract 

Background: The aim of this study was to investigate the reliability of bone profile tool for assessment of bone quality of potential implant sites using interactive computed tomography (CT) software.
Materials and Methods: CT examinations of 80 patients with 150 potential implant sites in the maxillae and mandible were included. Trabecular bone density was evaluated using Hounsfield unit (HU) values in rectangular regions of interest on axial dicom images and on reformatted cross-sectional images. Bone density profile line measurement was made at three sites in each reformatted image.
Results: The HU bone density values with profile line method were highly correlated with values from the rectangular region of interests (ROIs) in cross-sectional images.
Conclusion: This study suggests that the profile line method might be a valid and useful tool for pre-implant trabecular bone density assessment.

Keywords: Computed tomography, interactive software, regions of interest, trabecular bone density


How to cite this article:
Chaturvedi A, Sahai S, Sahai A, Raval M. Validation of trabecular bone density profile at potential implant sites as a simple and accurate predictor of bone quality. J Dent Implant 2013;3:16-20

How to cite this URL:
Chaturvedi A, Sahai S, Sahai A, Raval M. Validation of trabecular bone density profile at potential implant sites as a simple and accurate predictor of bone quality. J Dent Implant [serial online] 2013 [cited 2020 Sep 18];3:16-20. Available from: http://www.jdionline.org/text.asp?2013/3/1/16/111674


   Introduction Top


Bone quality is a collective term referring to mechanical properties, architecture, degree of mineralization of matrix, and chemistry and structure of bone mineral crystals, which are the remodeling properties of bone (Shapurian). [1] Computed tomography (CT) images were established for direct density measurements and expressed in Hounsfield units (HU). [2] Accurate analysis of the bone content and architecture would facilitate clinical decision-making regarding patient selection, implant type and surface, and the surgical technique to be used. Quantitative computed tomography (QCT) is an established method for measurement of bone mineral density, and it provides quantitative data of trabecular and cortical bone. [3],[4] Previous studies have measured HU bone density using different methods based on axial dicom or reformatted images. [5]

Reformatted cross-sections are the preferred plane for implant treatment planning, which should also provide qualitative assessment. Interactive CT software specifically designed for implant surgery provides the HU bone density in rectangular regions of interest and also graphically along a line with the bone profile tool. The bone profile tool gives variation of HU bone density along the profile line; however, the tool has not been validated as a predictor of bone quality.

This study aims to validate the accuracy of HU bone density assessment with the profile line method against HU density in rectangular region of interests (ROIs) measured on axial and reformatted cross-sectional images in the same sites.


   Materials and Methods Top


CT scans of 80 patients with 150 potential implant sites in posterior maxillae and mandible were selected for the study. Measurements were made at 114 potential implant sites, while 36 sites proximal to metallic restorations were excluded.

Axial dicom images (0.75-mm thick) at 0.5-mm intervals (Syngo CT Siemens Ltd., Erlangen, Germany) were used as the input data for Ondemand 3d TM (Cybermed Inc, Korea) interactive CT software.

Cross-sectional reformatted images were reconstructed at 1.5-mm intervals along panoramic curve on the maxillary or mandibular alveolus. The area of interest was localized on axial dicom and cross-sectional images using interactive cross-hair markers.

Trabecular bone density was measured in 8 × 10 mm 2 rectangular ROIs at three levels on axial sections [Figure 1] and at three levels on a single corresponding reformatted cross-section [Figure 2]. The bone density profile line was drawn along the ridge axis on cross-sectional images for each site [Figure 3].
Figure 1: Rectangular region of interest on axial section

Click here to view
Figure 2: Sub-crestal region of interest in the middle third of the corresponding cross- section

Click here to view
Figure 3: Profile line drawn along length of cross-sectional ROI shows HU bone density graph

Click here to view


The axial and cross-sectional methods measured three values of each minimum, maximum, and average of each patient; however, the profile line method recorded only minimum and maximum HU value. For correlation average value of these three points for minimum, maximum, and average bone density were calculated. Simple contrast with Bonferroni adjustment was applied to test significant difference of mean bone density between the pairs of methods. Simple linear correlation was used to find the correlation between methods for each minimum, maximum, and average values of bone density.


   Results Top


A total of 35% female and 65% male subjects were included in this study, of which 47% subjects aged <55 years and 53% subjects aged ≥55 years.

The gender, age, and jaw did not influence the correlation between methods for each minimum, maximum, and average values. Simple contrast with Bonferroni adjustment indicated the mean bone density by axial method, and it was statistically significant with mean bone density by cross-sectional and profile line for minimum and maximum [Table 1].
Table 1: Comparison of mean bone density among the methods

Click here to view


The minimum mean bone density by cross-sectional method was significantly different with mean bone density by profile line, but maximum mean bone density by cross-sectional was not significant with maximum mean bone density by profile. However, the mean of average bone density by cross-sectional was not significant with average bone density by the axial method [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11] and [Figure 12].
Figure 4: Scatter plot showing minimum bone density assessed by three methods. Bone density by the cross-sectional and profile line method was closer than the axial method in most sites

Click here to view
Figure 5: Scatter plot showing the maximum bone density measured by three methods for each site. The maximum bone densities assessed by cross-sectional and profile line methods were closer in most sites than the axial method

Click here to view
Figure 6: Scatter plot for average bone density assessed by the axial method and cross-sectional method. The average bone density assessed by the axial method is higher than cross-sectional method for less than 500 HU, whereas average bone density assessed by the axial method is less than the cross-sectional method for more than 500 HU

Click here to view
Figure 7: Scatter plot of minimum bone density values assessed by the axial and cross-sectional method. The line of equality represents the minimum bone density assessed by the cross-sectional method is higher than the axial method in most sites. The average minimum bone density measured by cross-sectional method is higher than the axial methods at every level of bone density

Click here to view
Figure 8: Scatter plot of maximum bone density assessed by the axial method and cross-sectional method. The line of equality represents that at almost all points, maximum bone density by the axial method is higher than by the cross-sectional method. The average maximum bone density measured by the axial method is higher than bone density measured by the cross-sectional method

Click here to view
Figure 9: Scatter plot of minimum bone density assessed by the profile and axial method. The slope is 0.83 and the intercept is 239.17. The Pearson correlation is 0.62. The average bone density assessed by the profile methods is higher than the average bone density measured by the axial method

Click here to view
Figure 10: Scatter plot of maximum bone density assessed by the profile and axial method. The line of equality represents that at almost all points, maximum bone density by the axial method is higher than by the profile method. The average maximum bone density measured by the axial method is higher than the bone density measured by the profile method

Click here to view
Figure 11: Scatter plot of minimum bone density assessed by the profile and cross-sectional method. The slope is 0.94 and the intercept is 36. The bone density values are almost equally distributed from the line of equality by the two methods. The bias is 33.53 and bias ±2 SD is -227-294

Click here to view
Figure 12: Scatter plot of maximum bone density assessed by the profile and cross-sectional method. The slope is 0.93 and intercept is 21.43. The bias (mean difference) is 25.44 and bias ±2 SD is -289-239, which shows almost equal points below and above the line of equality. The bone density values are almost equally distributed from the line of equality by the two methods

Click here to view



   Discussion Top


CT HU is based on a linear scale defined only by two points: The attenuation of dry air, set at -1000 HU and the attenuation of pure water at 25°C, set at 0 HU. Cortical bone may show HU values in the range +1,000 to +1,600. Trabecular bone shows lower HU values. Negative readings might indicate that the trabecular bone has been mostly replaced by fat. [6],[7]

Cross-sectional or para-axial images were used for assessment of trabecular bone density because pre-implant quantitative bone assessment is also performed on these sections. This approach was previously used by Masih, et al. [2]

A rectangular area of 8.0 × 10.0 mm was selected as the ROI to map out a trabecular region using the available software on axial and cross-sectional images. Minimal or no inclusion of the adjacent cortex was attempted. In many sites, because of the ridge anatomy, the superior aspect of a dense crest was not included and, in some regions, small cortical inclusion could not be excluded because of thick cortical plates or acute ridge angulation. Therefore, bone density measurements within some regions registered a negative value reflecting high fat content of the marrow in this area, while the upper limit observed was of the order of 1200 HU for certain axial measurements.

The upper and lower limits were considered to have limited diagnostic value as implants usually interact with bone of varying densities along its entire length, both with and without cortical fixation. [8] Our inference to the above observation would be to further emphasize the usefulness of the profile line tool instead of adapting a subjective scoring system.

Limited correlation of the axial bone density measurements was possible with those obtained using the cross-sectional or profile line methods due to perpendicular planes of sectioning and differences in the actual area analyzed.

Maximum and minimum bone density values obtained with the cross-sectional and profile line was almost equally distributed from the line of equality. The observation could partially be due to the small size of the ROI used in the study, with a large coincidence of the sites of measurement.

A major drawback of the profile line method is the absence of discrete spatial HU values and mean HU value, thus permitting limited correlation with axial and cross-sectional methods. However, the maximum and minimum HU bone density values with cross-sectional method show significant correlation with the axial method. Maximum and minimum bone density values with the profile line method were highly correlated with values from the cross-sectional method.


   Conclusion Top


Therefore, the profile line method is a simple and accurate tool for trabecular bone density assessment that would require further study with prospective clinical trials.

 
   References Top

1.Shapurian T, Damoulis PD, Reiser GM, Griffin TJ, Rand WM. Quantitative evaluation of bone density using the Hounsfield index. Int J Oral Maxillofac Implants 2006;21:290-7.  Back to cited text no. 1
    
2.Shahlaie M, Gantes B, Schulz E, Riqqs M, Crigger M. Bone density assessments of dental implant sites: 1. Quantitative computed tomography. Int J Oral Maxillofac Implants 2003;18:224-31.  Back to cited text no. 2
    
3.Cann CE. Quantitative CT for determination of bone mineral density: A review. Radiology 1988;166:509-22.  Back to cited text no. 3
    
4.Genant HK, Steiger P, Block JE, Glueer CC, Ettinger B, Harris ST. Quantitative computed tomography: Update. Calcif Tissue Int 1987;41:179-86.  Back to cited text no. 4
    
5.De Oliveira RC, Leles CR, Normanha LM, Lindh C, Riberio-Rotto RF. Assessments of trabecular bone density at implant sites on CT images. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;105:231-8.  Back to cited text no. 5
    
6.Norton MR, Gamble C. Bone classification: An objective scale of bone density using the computerized tomography scan. Clin Oral Implants Res 2001;12:79-84.  Back to cited text no. 6
    
7.Lindh C, Nilsson M, Klinge B, Petersson A. Quantitative computed tomography of trabecular bone in the mandible. Dentomaxillofac Radiol 1996;25:146-50.  Back to cited text no. 7
    
8.Lekholm U, Zarb GA. Patient selection and preparation. In: Brånemark P-I, Zarb GA, Albrektsson T, editors. Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago: Quintessence; 1985. p. 199-209.  Back to cited text no. 8
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]
 
 
    Tables

  [Table 1]



 

Top
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
    Abstract
   Introduction
    Materials and Me...
   Results
   Discussion
   Conclusion
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed2099    
    Printed102    
    Emailed0    
    PDF Downloaded399    
    Comments [Add]    

Recommend this journal