Surgical Guide Stents for Implants: Compromise on Prosthetics to Obtain Better Placement?

Refer to a specialist to do these bone grafts for you and once the patient fully heals, place the implant. Don't take short cuts out cut corners. Do what is best for your patient. If he she needs a bone graft or sinus lift, recommend the right thing.

Dr. L. Consider for a minute what we are trying to accomplish by placing implants in any patient. Typically the top four things would probably be improved function, esthetics, comfort and longevity. That said, all prosthetic cases involve some degree of compromise - it's up to you determine where to draw the line between acceptable and unacceptable. There is probably no realistic way that this forum can help you define where that line should be in any given case, even with more specifics. Placing implants in an "ideal" location with regard to existing bone can possibly compromise your longevity, esthetics or comfort objectives. This may be the case if the abutments required significant angulation which would result in moderate off-axis loading. Inappropriate spacing and smaller implant size (again if only existing bone is considered) are also issues that can tempt us into recommending simplified treatment approaches that many times do not work. Treatment decisions and plans are best made in a combined sense for each patient using the many recommended guidelines available and your personal clinical experience. If you don't have a comfort level with a particular case, consider local study clubs or asking for help from an experienced implant surgeon. Most clinician's are approachable and all of us need help at times. Each difficult case that you plan and treat successfully will make the next one that much easier. Each dollar saved the patient (or surgical procedure eliminated) from a failed case will never be appreciated. Good Luck! Dr. No

I would present to the optimum implant placement for the prosthetic design, and that may require bone grafting. If the patient cannot go with the optimum treatment, then I would consider the alternative treatment with different implant placement. The aesthetics may be compromised, but the restorative support requirements should not be compromised. But at least the patient was presented and informed with the optimum plan.

Wanted to, but didn't respond to one part of your question: - - "However, it appears that the the fabrication of a surgical guide stent is also very much driven by the prosthetic needs of the case. In other words, the implant fixture is placed where the best possible circumstance for the prosthetic rehabilitation can be obtained and not necessarily where there is adequate bone volume or density." - - Using a CT (or CBCT) and computer driven implant planning software gives you (and/or the planner) the option to at least try and obtain the best of both worlds (that's one of it's big advantages.) You can specify "ideal" crown position by having the patient wear a scan appliance (an RPD with ideally placed radio-opaque prosthetic teeth) during the scan. Those opaque teeth are visible in the planning software and, while it is true that the implants are usually placed with the best prosthetic crown position in mind, you dictate where the implants go. In some instances, you may determine that there is sufficient acceptable bone available and that a solid implant position/prosthetic compromise is available without grafting - sometimes not. Also, you can typically define, elongate or otherwise alter virtual prosthetic crowns in the software. This will enable you to provide the patient (and yourself) a three dimensional look at the finished product if the implants are placed as specified. In simplest terms, CT's and computer aided planning software just provide you with much more information enabling you the opportunity make better decisions. That and good judgement make for well defined, more predictable and successful treatment plans. Dr. No

You should not be afraid to use bone grafting or sinus lift proceedures to develop your sight. After all your goal is most likly to provide a final case with maximum comfort ,function, esthetics and also longeviety. In order to do this you need to place implants in relatively good prosthetic positions and also in good quality and quantity of bone. In other words your computer driven guides should help achieve all of your objectives with minimal comprimise.

All above comments are great, however, I'd like to add just a hint to help in your final judgement. Yes, in a perfect world, ALL implants line up exactly with the imaginary roots of our ideal final crowns/prostheses. Yes, in the real world, this is often not possble. So, you need to be looking for the least angled implant position with an abutment long axis of which will intersect with a line between the contact points of the adjacent teeth. Some posterior mandibular implants may need a slight lingual apical position to avoid inferior alveolar nerve. Some anterior mandibular implants may need a slight lingual slant of the coronal end to avoid penetration. Most maxillary implants will need a slight lingual positioning of the apex to engage sturdy bone. Of course, the sinus lift sites can usually be implanted more vertically. Aim for the minimally angled abutments you can get and still stay within your predetermined prosthetic target. Best thing to do is to make a removable partial denture or full denture set up and tested on patient to arrive at your end goal right at the start - before any other work is done. The 3-D x-rays are nice, but not much help if you do not have a reliable transfer device like described above. These pre-treatment planning procedures will go a long way in giving you and the patient comfortable, reliable treatment visits. And, if a surprise comes along, you've got all the info you need beforehand. I would, however, advise some caution in the stents purported to guide your implant drill bits to the perfect angle and depth. There are many surprises in the bone - softness, hardness, inclusions,et.. The stents could have a flap or something under them or not be completely seated. You need to be able to feel and adapt the preparation at all stages as you deem necessary. I like the Bicon, slow prep reamers and hand reamers since one set does not cut on the end and the other barely cuts on the side. Only the first pilot drill cuts fast on the tip. As such, you can feel the reamers slide along the lingual cortical bone on the lower, the upper palatal, and anything they run into in between BEFORE you actually cut into it. It's pretty difficult to drill through an inferior cortical plate with a non-end cutting reamer. You can feel it bump into pdl's, and other cortical areas in the bone without any damage, esp. at 20-50 rpm. John John

Dr. Funari, raises an interesting issue. He says to the guy just getting his feet wet,with implants,to not be afraid to do sinus lifts and grafts. Let's not forget ,that he hasn't placed many implants , so he is most likely not ready to be doing any grafting aside from socket preservation . Onlay, ridge splitting and sandwich grafting can be quite challenging. Albiet, you may see a lot of ct generated guides in the literature, they are less than commonplace and are marketed in such a way, that some companies suggest the implants can be placed blindly,with little knowledge or experience . A good prosthodontist can restore just about any implant that is close to where it needs to be. Remember, there are limitations to everything we do. Treat a couple of bad burn patients and you will understand what I am saying. Mount models and do wax ups!!! Bv

I like all of John Manuel's comments but especially the one's about slow speed and the Bicon hand reamers. Can't think of a better way to snatch defeat from the jaws of victory then to over rev. the drills and devitalize bone. Likewise, using dull cutting instruments can also help you lose an otherwise good case. I would hate to guess how many early implant failures that these have contributed to. I tend to also believe that some to many of the so called post-op infections are nothing more than localized reactions to non-vital bone caused by rotary instrumentation abuses. On the really difficult cases, I will often pull out the Bicon reamers to better control the osteotomy regardless of the type implant that I am placing (just use the correct system drill for the final cut.) Lastly, I feel that the final drilling is the most important and should be run the slowest - as John says, 20-50 RPM with light pressure. Dr. No

The desired prosthetic outcome should dictate implant placement. Twen ty or so years ago, if an implant integrated, it was declared a success, regardless of the spacing and inclination. Today, if sufficient bone volume doesn't coincide with the prosthetic need, then bone volume is created to coincide with the prosthetic need. A waxup should guide you.

I keep bringing the " team approach " concept up, with little response. Is it because it's makes too much sense, or is it because it takes dollars out of the hand of the doctor trying to improve his/her skills in implant surgery. If you in fact start placing implants,it is 100 percent in the best interest of your patient to at least refer out the bone graft portion of the case to someone VERY proficient in harvesting and managing all forms of these procedures. Don't start out placing fixtures in compromised positions,for God's sake you have to restore them. Surgical guides are in their relative infancy stage. Some cbct company reps can't even begin to explain how to proceed. Let's assume one of your new guides was fabricated from a stand up ct scanner, and the patient moved,unbenounced to the technician,do you think the flapless blind surgery is a safe bet? I absolutely could not work without my scanner since I obtained it but nothing takes the place of experiance and knowledge of the anatomy. There are several simple implant cases out there ! There is no I in team. Sorry ,couldn't resist. Bv