3D CBCT Report November 2011 Issue 3D CBCT Case Study Daniel McEowen, DDS Hagerstown, Maryland Failed endodontics is a common problem in dental practice today. More and more doctors and patients are exploring the option of extraction and implant placement over a retreatment of an existing root canal. In some cases adequate bone is not available post extraction and grafting can be a necessity. The following case is a good example of this problem. The patient is a 26 year old female with chronic infections in tooth #14 (Fig. 1). This sagital cross section shows a chronic periapical lesion, gross decay to the bone level. It also shows a collapsed sinus extending into the furcation of the roots. The coronal cross section (Fig. 2) clearly shows both gross decay and a severely pneumatized sinus. The tooth was determined to be non-restorable and after presentation of treatment options, the patient elected for tooth extraction and implant placement. From this view we again see the lack of bone in the interproximal area of the roots. The axial projection (Fig. 3) again demonstrates the large extent of caries and breakdown of the tooth structure in and around the palatal root. With careful removal of the tooth the buccal and lingual walls of the socket can be preserved and provide a matrix for the bone grafting. The detailed information proved by the 3D CBCT images is critical for accurate implant planning. The saggital view (Fig. 4) provides a precise and true view of the remaining bone in the extraction site compared to the PA x-ray (Fig. 5). These sinuses are extremely pneumatized for such a young patient. We have two options for grafting in most cases of inadequate bone height and width. Because the width of the molar and size of the sinus the first option in this area would be a lateral window graft. Option two would be an up fracture of the sinus floor with addition of bone materials. Given the Fig. 1 Fig. 2 Chronic infections Gross decay and a severely pneumatized sinus Page 1 of 3D CBCT Report
Fig. 3 Fig. 4 Fig. 5 Fig. 6 shape of the roots and the surface shape of the remaining bone there would be a high probability of perforation of the sinus membrane. With a normal panorex scan a lateral wall sinus lift and graft to build up sufficient bone would be the treatment of choice. With the use of CBCT we will see a different picture leading to a change in treatment planning. The additional views available in the 3D mode are of critical importance in the final diagnosis of this case. As seen in the following images, there is great detail in the views of the floor of the sinuses as well as the lateral walls. The 3D sagital projection (Fig. 6) gives a good view of the sinus floor extended into and around the furcation. Fig. 7 Fig. 8 Page 2 of 3D CBCT Report
The 3D view (Fig. 7) confirms collapsed sinus and an over extension of the gutta percha into the sinus cavity The importance of the next view shows the superior sinus artery is clearly defined (Fig. 8) and using the marking tool/ function in the 3D mode is highlighted by the yellow arrows. Of significance is the proximity to the apex of the roots to the artery position. The lack of adequate spacing between the roots and the blood vessel prevent a safe opening of the lateral sinus graft window, this prevents us from using that treatment option. Traditional 2D x-rays of this artery would not have revealed this artery and could have resulted in a hemorragic episode and associated complications. Based on our findings from the diagnosis of the CBCT images, a sinus lift was performed through the floor of the sinus, elevating the apical portion of the bony socket avoiding the lateral artery. In conclusion, w/o out the use of 3D CBCT images, this case could have resulted in serious complications. CBCT and allowed a favorable outcome for the patient. About Dr. McEowen Dr. McEowen is a 1982 graduate of Loma Linda School of Dentistry and has been in private practice for 26 years. He is in a multidiscipline practice in Hagerstown, Maryland where he has incorporated many advanced technologies. He is a founding member of the WCLI (World Clinical Laser Institute) achieving a Mastership level of proficiency. He has been active in FDA approvals of oral surgery techniques using Erbium lasers and has lectured internationally about techniques using lasers in general and specialty dental fields. He is a member of the ICOI and has lectured at several ICOI and AAID meetings concerning the use of CBCT in implantology. Dr. McEowen has been involved in Conebeam technology for over seven years and owned an Imaging Center in Maryland. Page 3 of 3D CBCT Report
Clinical Case Robert Odegard, DDS, MAGD, DICOI Renton, Washington Four years ago, before I had my Prexion3D CBCT, I used digital periapical and panoramic radiographs to assess prospective implant sites. I did a careful analysis of the amount of available bone, the proximity of vital structures such as the location of the inferior alveolar nerve, maxillary sinus, nasal cavity etc. I sometimes would place 5mm steel radiographic markers pre-radiographically in order to calibrate the digital measuring tools to compensate for radiographic distortion. Even though I spent a lot of time planning my implant cases, and scrutinizing the radiographs and study models, without a clear view of the cross sectional anatomy, I was blind in my approach. This is because, panoramic and intraoral radiographs limit the clinician s ability to assess the bucco-lingual dimension of the anatomy due to their 2-dimensional nature. I am grateful that I never encountered a significant anatomical aberration which could have led to a very costly error; however, since I have had my Prexion 3D CBCT, I have identified many unusual anatomical variations prior to treatment causing me to adjust my surgical plan, which may have saved me from severe problems in my implant surgeries. In the posterior mandible, certain risks and complications associated with implant surgeries may occur. For example, violation of the implant structure beyond the alveolus may result in infection, loss of the implant, loss of bone, destruction of a desirable implant site, hemorrhage and even death of the patient. In this month s ICOI publication of Implant Dentistry, Volume 20/Number 5/October 2011, there is an article titled Risk of Lingual Plate Perforation During Implant Placement in the Posterior Mandible: A Human Cadaver Study. In this article by Daylene Jack-Min Leong et al, the author points out that damage to vital anatomical structures may lead to neurological injuries; and perforation of the lingual cortex may result in severe hemorrhage of the floor of the mouth which may potentially be fatal when it obstructs the upper respiratory tract. In fact, the author goes on to report that since 1960, there have been 14 cases of life threatening bleeding associated with the placement of dental implants. In the following case, a typical panoramic radiograph showed that this patient appeared to have good vertical bone height for excellent implant planning and placement. Look at Figures 1-3. Fig. 1 is a cross sectional view taken after the implants were placed in the posterior mandible. Notice the severe curvature in her mandible from the mylohyoid fossa. This explains clearly the value of 3D cross sectional imaging in pre-implant surgical planning. Without this cross sectional information, that is not available from the panoramic or intraoral radiography, I may have perforated this woman s lingual plate which could have resulted in severe hemorrhage (from damage to the lingual peri-mandibular vessels) and possibly resulted in serious complications from respiratory obstruction. As a result, a shorter implant was used in order to avoid a catastrophe, I feel much safer placing implants in my dental office since I have had my Prexion scanner. All areas planned for fixture placement or augmentation should be scanned and examined in cross sectional views prior to surgery. This will lead to much better surgical outcomes and prevent possible disasters. Page 4 of 3D CBCT Report
Fig. 1: From the 2-dimensional radiographic evaluation, there appeared to be plenty of vertical height from the alveolar crest to the inferior alveolar nerve allowing for at least a 12mm implant, however 3D cross sectional viewing from the Prexion unveils a drastic curvature in the mandibular body. A shorter implant was placed in order to avoid perforating the lingual cortex. Fig. 2 ABOUT DR. ODEGARD Dr. Odegard graduated from the University of Washington School of Dentistry in 1989. He is a Master in the Academy of General Dentistry and a Diplomate in the International Congress of Oral Implantologists. Dr. Odegard is a general dentist and since 1991 has run a solo private practice in the Renton Highlands/Seattle area. Fig. 3 Page 5 of 3D CBCT Report
The Imaging Chain Powerful, Easy-To-Use Software 1. Focal spot size 2. Voxel size 3. Optical vs. digital zoom 4. Degrees of rotation 5. Number of projections 6. Software capabilities Over the last four months we have examined the importance of image quality in accurate, complete diagnosis and precise treatment planning. Recently at the American Dental Association meeting, a dentist compared PreXion3D s high quality, clear images to the difference between performing dentistry without loupes or better yet, without a microscope. These images give dentists complete information and eliminate the guess work of dentistry. In this issue of the 3D CBCT REPORT, we will discuss another critical but often overlooked factor to creating high quality images, software capabilities. PreXion has a long heritage of focusing on image quality and diagnostic capability dating back fourteen years. PreXion is a spin-off company of TeraRecon, Inc. (www.terarecon. com), a technology solutions leader and provider of advanced 3D imaging systems for medical and industrial applications since 1997. Thousands of hospitals around the world rely on TeraRecon s powerful software for complex cardiatric, neurologic and other diagnostic and treatment planning needs. These same leading medical software capabilities and tools are available to the dental community in the PreXion3D system. The Prexion3D system is specifically designed for volume rendering (hence the name) and easily allows multiple simultaneous datasets to be rendered with very minimum load on the computer. The Prexion3D system has a true server/client solution, also called a Thin Client, which was brought to the medical imaging market by TeraRecon, so you don t need powerful computers/ clients in your operatories to process the images and in almost all cases you don t need to upgrade your computers. All datasets always remain on the server, which means when using your various work stations throughout your office you can load datasets as fast as you would from the powerful console computer. PreXion s Thin Client solution also means you don t need to compress files, compression will cause a loss of image quality. Page 6 of 3D CBCT Report
The Imaging Chain: Powerful, Easy-to-Use Software Thin vs. Thick Clients A Thick client requires that each remote computer does its own processing/computing and does not use a main server. In this case, each computer running the CBCT viewing software needs to have a full blown version of the viewing software to function. A Thick Client system needs to have relatively powerful computers/processors whenever using the CBCT system. Disadvantages: Slow transfer of data Need for powerful computers in each operatory to ensure fast rendering and quick responses Processing will tend to be sluggish on slower computers Degraded image quality due to the need to compress data A Thin client does as little processing as possible on the remote computer and relies on accessing the server each time input data needs to be processed or validated. Advantages: Data sets are not transferred to the remote computer Remote computer does not need to be a powerful system since processing is done on the main server Data sets are kept on the main server for processing and visualization PreXion s proprietary system allows for rapid rendering, processing and manipulation of high quality images Eliminates data transfer issues and problems Reduces security problems related to data transfer and using data on remote computers Page 7 of 3D CBCT Report
Interviews George Loftus, DDS Coeur d Alene, Idaho Dr. Loftus, what were the factors that got you interested in 3D CBCT? I have been doing implant surgery since 1988 but limited my cases to predictable cases and in the past had referred everything else out to specialists. My main interest in cone beam technology was to give me the ability to better diagnose and do more accurate treatment plans. I did not want to have to send my patients elsewhere for scans and started evaluating various cone beam systems. How will having a 3D CBCT system in your practice impact your practice? I have been performing from 50-100 implant placements per year. After viewing PreXion3D images since the installation in mid- October, my level of confidence has increased and my quantity of implant placements will increase. These images are allowing me to see exactly what the quality and quantity of bone is and where I need to do bone grafts prior to implant placement. It also has given me an incredible tool to inform and educate patients about treatment options. I am finding patients asking for additional treatment options, since you are doing this implant, can you also do the other side?. Can you elaborate on your comment about an increase in your confidence level? Having more complete and more accurate information has taken the guesswork of procedures and given me more confidence to take on larger and more complex cases than I had in the past. This is resulting in fewer referrals to specialists and is keeping more patients in my practice. Using only 2D x-rays made it difficult to perform a full mouth case. With this detailed information from my CBCT system, I have become more aware of things to look for to avoid complications including the status of the sinus, nerve position, lingual fossa, thin bone areas, etc. Why did you purchase PreXion when there are so many other CBCT systems on the market? I had been looking at CBCT systems for two years and watching the improvements in the PreXion3D system including software upgrades, higher quality panos and lower radiation levels. In addition to PreXion s reputation for the highest quality images, I was impressed with the software s ease of use and the convenience of being able to see all four views at the same time. I was also looking for a cost effective system and liked Prexion s price and ongoing costs for service, they were very reasonable. The PreXion Regional Manager and other personnel were also very knowledgeable, professional and helpful giving me confidence of good support down the road. About DR. Loftus George J. Loftus III, DDS, is a 1985 graduate of Georgetown University s School of Dentistry and has been practicing general dentistry for over 25 years. Dr. Loftus founded A Center For Dental Health in 1993. Before moving to Coeur d Alene he ran a dental practice in California for 8 years. Dr. Loftus has achieved his Fellowship in the Academy of General Dentistry, Standard Proficiency Certification in the Academy of Laser Dentistry, has a Certificate in Conscious Sedation from the American Dental Society of Dental Anesthesiology and is a member of the Academy of General Dentistry, American Dental Association, Idaho State Dental Association, Panhandle District Dental Society, American Academy of Implantology, Academy of Laser Dentistry, Dental Organization for Conscious Sedation and the Inland Empire Perio Study Club. Page 8 of 3D CBCT Report
PreXtips Use of the Line Segment Function for Measurement of Curved Anatomical Areas Measuring a curved region of dental anatomy is easy using the PreXion measurement function. Start by clicking on the measurement icon at the mid upper toolbar which opens up its functions. Arrow to the 4th icon over and note is will display as Line Segment. Left click 1x and drag the caliper to start and left click along the curve as segments. When the end is reached then left click 2x for the total distance to be displayed in units of mm. To delete and redo if necessary then right click on the unit value mm and delete or click the red X delete icon at the upper toolbar and delete on the measurement (Fig. 1). Any curvature in any area of dental anatomy can be measured using this method. Fig. 1 If you need additional assistance with this procedure, call us toll free at 1-855-PreXion. Page 9 of 3D CBCT Report