The BASIC Revised Bone Sounding Protocol

Bone soundings (soft tissue thickness measurements) of the proposed implant placement site is one of the five important patient records necessary in the BASIC case selection process. This measurement record is critical information in the construction of the transverse site cut Model-Tomographic ™. This need for accuracy ultimately culminates in the BASIC 3D channel drilling guide stent that places the body of the implant so as to use fully the existing but hidden bone volume and blood supply. And if that we not reason enough the Tomographic also allows for the best functional and esthetic placement as well. Therefore these easily attained measurements often taken without injection anesthesia by virtue of small acupuncture needles are truly important!

Previously our protocol asked for five (5) soundings rather equally spaced about the proposed site. This technique has served us and our client doctors well, but some new anatomic information has come to light, and was gleaned from a recent journal article pertaining to inadvertent channel drilling that perforated the lingual cortical plate of the mandible*. In the article mention was made of the sub-mandibular artery. The specific area in question occurs inferior to the lingual mylohyoid crest, and is referred to as the sub-lingual fossa region. It has been recently determined that infrequently some collateral branches of the artery can be found in this fossa area that houses to some degree the sub-mandibular salivary gland. Therefore there exists a slight chance of penetrating one of these branches when making a fossa bone sounding. This could possibly result in interstitial bleeding that could go unnoticed until floor of the mouth swelling might occur. Again this risk is small and h as not occurred to any of our client doctors, but even so a slight risk becomes 100% when it happens to us. Up to this point in time the carefully constructed Model-Tomographic™, and a subsequent 3D drill guide stent has functioned exactly as it should in keeping our doctors mandibular implant channel drilling well into safe bone site regions and away from the lingual cortical plate. So what caught our interest is this anatomic finding of possible collateral circulation however infrequent. Therefore we ask you to follow the new bone sounding diagram and stay above possible risk.

A second change that we are advocating is now making three (3) sounding penetrations of crestal tissue instead of the former single mid crest occlusal measurement. Yes we still need to know the tissue thickness mid-crest for guide height and prosthetic reasons, but it is also beneficial to know the crestal bone anatomy as well. If there is present a bony peak or depression the three (3) measurement penetrations of the crestal tissue will help alert us of the fact. This is done by offsetting the second and third penetration some 2 to 3mm facial and intra-orally. A transverse cut diagram of the ridge site showing the former and new soundings points would resemble the following for the mandible from bicuspid and posterior molar regions. The fossa depth becoming more pronounced the further posterior we go:

With better knowledge of the crestal bone sit anatomywe will be alerted to the importance of the 'divot' or drilling start point indentation so that the pilot drilling will be true and not "slip off" the peaked crest into misdirection. These three sounding measurements also tell us more about whether or not the neck diameter of the implant should be 3.5, 4.0, or 4.5mm with respect to the bone volume and blood supply present at the crest. Or would better success be attained if a concurrent bone regeneration procedure were to be initiated? From these examples it can be seen that just two more accurate tissue thickness measurements provide us with extremely useful information and important to a successful implant placement outcome.

Finally it will be noted again that this altered protocol deletes the tissue thickness information in the fossa depression area. And as was mentioned before this is possibly our most critical area from a drilling direction standpoint, so that the lingual cortical plate is not perforated. So what's going on? Well what's going on, has we think been addressed even more accurately than before. For a year BASIC has been evaluating different methods, materials, and disposables to accurately reproducean impression, a cast that will truly provide us with pertinent existing anatomy of the proposed implant sites irregardless of arch or area. Thnew BASIC anatomical impression protocol serves well to pick up correanatomy from a shape, depth, and extent standpoint and therefore a marked advantage over more routine static impressions utilized in att Lingual Tissue "drape" Mylohyoid Crest Sounding Submandibular Gland standard diagnostic dental casts. Then as far as the tissue thickness is concerned we are utilizing a 2mm tissue thickness incorporated into theTomographic. This is very generous because when the soft tissue drape iphysically placed into intimate contact with the lingual cortical plate of the lingual fossa as the glandular tissue is eased aside by the finger pressurized pretty material, the tissue is actually only about 1mm thickness! Please see the anatomical impression paper. This changedsounding protocol is advocated in the mandibular arch as far forward as cuspid sites. There can be definite undercut areas present in the bicuspid regions so adjust the tray flange as appropriate.

It is always indicated to palpate lingually for any mandibular implant site to check for undercut presence and extent – even beneath an exostosis if present. BASIC does not advocate any sublingual bonsoundings in a mandibular cuspid to cuspid region due to significant arterial circulation in this area. Anatomical casts, very careful lingual flapping and profile radiography is indicated when placing implants ofsize in this region.

Also anatomical casts are indicated for maxillary arch especially anteriorly, due to sometimes significant apical depressions present in anterior sites. For the maxillary site the soundings will number seven (7) for all sites:

We strongly believe that this altered bone sounding protocol along with anatomical impressions will prove to be superior in all areas of the arches when selecting acceptable sites. From these changes, the Model-Tomographic™ will be even more accurate.