panoramic bone indices can provide the pattern of bone resorption also you can use the bone  between the lower border of the inferior alveolar canal and the lower border of the mandible as index of bone quality. Another index can be used is in the angle of the mandible . By these indices with Dexa you can assess the bone quality for dental implant. There were many researches about the use of previous indices to evaluate osteoporosis so on the same principles you can assess the bone quality for dental implants.    

hello: one of my students did a master degree with me  on the accuracy of the bone level  and the inferior alveolar nerve and our results show that the Ct scan is as good as the actual caliber measure and we published a paper  Article: Determining Position of the Inferior Alveolar Nerve via Anatomical Dissection and Micro–Computed Tomography in Preparation for Dental Implants Natalie D. Massey, BHSc, MSc; Khadry A. Galil, DDS, DO&MF Surg, PhD, FAGD, Cert Perio; Timothy D. Wilson, PhDk.a Galil which you can see in my publication

of course we use  now instead of the Ct scan we all use CB CT and the results are accurate ,I say this because using Panoramic X-ray  in  implants  show distortion of about  23% this has been cited in a paper by  Greenstein carvallo and tarnow entitled Review; Practical application of anatomy for the dental implant surgeon. J periodontology 2008.79;1833-1846.

so if  one wants to use a panoramic x-ray 23% distortion has to be taken in consideration.

Thank you

Prof galil

OPG has overlap of parts of mandible and it can be an issue when you try to standardise it unlike spine which can permit measurements without overlaps. Also the area of interest may have a specific less bone density when you are studying for implant placement. So it will mean that you must be able to use DEXA at that particular area. It may be possible to measure bone density with other custom methods if all one requires is measurement of the bone density at the particular place (locally for implant placement). One study used a standard stepped aluminium strip with known densities and used a software to compare density of the area of interest with the known density. Also you can use fractal analysis. One study used a strip of different metals of known density for a similar study. These are standardised first using DEXA analysis and later applied to a large segment of patients.

So there are indeed ways but one must only think to get the idea into play. I am not sure exactly what you have in mind when you say you wish to standardize OPG with Dexa ... but there are ways to do so even without using Dexa is what I was implying (and that would be better as using DEXA method for analysis / study will mean additional exposure ..) Also the question arises, is DEXA analysis for all patients indiscriminately an option ? It may be permitted in patients with suspected osteoporosis but using it as a blanket procedure for screening for every implant case may be subject to severe criticisms. Another issue is, OPG is a 2D measure and will not accurately reflect on the bone density with respect to the alveolar bone quality.

And if there indeed a bone deficiency / thin bone, how would we plan to address the issue ? We might require an additional CBCT or CT scan to accurately analyse which areas have deficiency.

For example, let's consider two scenarios - one patient with thinned bone in a particular area following trauma (cortical bone thinning/loss) and another patient with a localized bone loss due to periodontal problem. How would your analysis differentiate between these two cases ? As DEXA only analyses the intensity modulation of a beam traversing the bone and exiting it on the other side. While both these scenarios may have similar readings / values, it would not be clinically useful data for implant placement as the case with cortical bone loss would be more difficult to manage than a case with internal alveolar bone thinning, I believe.

What exactly are we trying to measure in this scenario ? How would be make sure that our idea would be clinically relevant for implantology ? Another issue is how are we going to use DEXA for alveolar bone at a particular area of interest ? The alveolus is not easily accessible like fingers or spine! Also another important parameter is that the DEXA gives the "average" bone density across the area it measures using two differnet xray sources. So it still may not reflect on the ability to choose if a particular place has local bone defects which require different management etc;

A quantitative approach using fractal analysis of a digitized or digital xray would be good (an IOPA which has minimal overlap in the bon region) is my suggestion instead of OPG. Or using a comparative parameter would be a good idea as well if you are planning on using this bone density parameter in different persons. If you just want comparison of bone density in just the same patient or pre-post bone density around implants, you can use other techniques using standard intraoral structures like enamel / dentin of a sound tooth in the oral cavity. This way the exposure/ time/ mA, kV and distance are not critical as we are going to get a 'ratio' which will be constant and comparable. It's another technique to analyse the density. Infact, this technique of 'density analysis' is frequently used in CT scans when it's read by radiologists. They select the Hounsfield units for the area of interest and compare it to hounsfield units of known structures to suspect the contents of a lesion / tumor/swelling etc; Similarly we can use software to compare the pixel density to get this data. It sounds complicated but it is not all that if we pay attention to details.

Regards,

Dr. Akilesh. R