Federico: Chances are, you are doing nothing wrong.  In our laboratory we receive many 2-3 mm bone cores from implant dentists, and their skills seem not to be better than yours.  Because of this, some ask us to embed the bur with the biopsy.  Others that want to keep the bur simply push the biopsy through, which, yes, sometimes fragments the biopsy into pieces.  We have advised that when they push, they do so from the cutting end, allowing the biopsy to continue moving inside the bur in the same direction it was traveling when being taken.  This has seemed to improve things a little.  It is also obviously important that the rod you use to push the biopsy out through the back end of the bur should fill as much of the inside diameter as possible, but without sticking.    

Thank you all for the precious suggestions! I will try both technique with the next biopsies 

Federico: My answer as Otorhinolaryngologist (especially as a rhinoendoscopist) I can give it from the point of view of the patients with chronic rhinosinusitis (CRS). Histomorphometry analysis in CRS has been used by some authors to determine levels of evidence of histopathological changes including new bone formation, fibrosis, and presence of inflammatory cells. In these cases, bone tissue specimens of sinus bone walls are collected endoscopically and placed into a sterile container with sterile saline. Histomorphometry analysis in CRS is not performed routinely. In patients with CRS with underlying bone involvement, Sinus CT scan sinus can be identified preoperatively as areas of focal diffuse bone thickening. Underlying bone sclerosis, ostetic or hyperostosis changes should be evaluated in depth, because are usually associated with sinonasal tumors such as inverted papiloma and also can be a preoperative radiological sign of tumor anatomic origin by radiologists and Otorhinolaryngologists.

Dear Federico,

We had the same problem as you with the biopsies we have to process in our lab. In my opinion it is not advisable to push the biopsy out of the trephine burr, because it can break during this procedure. In many cases the biopsied material lies loosely inside of the trephine burr. When pressure is applied to push it out, its structural integrity can be destroyed or it gets condensed.

The best solution in our experience is to leave the biopsy inside of the trephine bur, embed both in plastic (e.g. Technovit 7200) and then produce thin ground sections.

Two examples can be seen with the following links:

http://histomorphometrie.meduniwien.ac.at/virtual_histology/Termis_Demo/30004013_P74_20x_efi_01%20-%2020x/index.html

http://histomorphometrie.meduniwien.ac.at/virtual_histology/Termis_Demo/4392A_1_P169_20x_efi_03%20-%2020x/index.html

You can increase and decrease magnification by using the scroll wheel of your mouse.

One disadvantage of leaving the biopsy inside of the trephine, is the fact that a µCT analysis of the tissues is encumbered by artefacts produced by the metal of the bur. If a detailed µCT analysis is necessary before the histology, we gently grind the trephine bur open with a handheld precision drill grinder (PROXXON GmbH, Föhren Germany) until the material is so thin that it can be removed with tweezers or carefully cut by a scalpel.

First we wrap the biopsy in 2 layers of transparent scotch tape to avoid contamination of tissues of the biopsy by grinding dust (b in figure). Then the metal of the burr is ground down tangentially on two opposing sides of the cylinder (c in figure).

Half of the cylinder can then be raised like a lid from a box (d in figure) and the biopsy is easily removed without damaging it. The biopsy can then be subjected directly to a µCT-scan or if it is very fragile first embedded in plastic and then scanned.

The grinding open of the trephine should also work for conventional paraffin histology. As the procedure is rather time consuming, make sure that the tissues don’t dry out and put a drop of water on them from time to time.

Dear Prof. Tangl

I am really thankful for your advices (even forward me the micro-ct issue).

I will share them with the laboratory personnel to optimize them with our means. As you probably understood we are trying to set up from "zero" a complete histomorphometric evaluation of bone core biopsies, and the issues are so many, thus I really thank you... who knows, maybe one day I will ask you to gently accept me to visit your department to learn from your experienced skills! till now I will take the lesson to heart.

sincerely

Federico