Pasadena, Texas Advanced 3-D X-rays:
Damage to the mandibular nerve (lower jaw nerve) is the most frequent and devastating problem of poor diagnosis, treatment planning, or surgical technique when placing dental implants. This is due to the fact that the mandibular nerve displays complexity and variation in its anatomical position in the jaw. Therefore, a complete radiographic evaluation is indicated to determine the ideal position for a dental implant with respect to the mandibular nerve.
All panoramic (2-D) X-rays show some degree of:
- Uneven magnification
- Image superimposition
These 2-D imaging errors can possibly lead to incorrect measurements and assessments of anatomical structures. Furthermore, the mandibular canal represented on panoramic images is not always clearly defined because of inconsistent anatomical borders. Multiple, studies have established that panoramic X-rays are unreliable and incorrect in evaluating the exact location of the mandibular nerve canal. Plus, on panoramic images the mandibular canal is not visible in approximately 36% of images. In conjunction with, the superior aspect of the nerve canal is not visible in 64% of X-rays. Therefore, extreme caution should be used when only using 2-D X-rays for implant site evaluation.
Disadvantages and Limitations of 2-D X-rays when placing Dental Implants:
Today, the singular use of 2-D X-rays for treatment planning of dental implant patients is becoming less common. Two-dimensional X-rays, mainly panoramic, have many intrinsic disadvantages in assessing potential dental implant sites.
Cone Beam Computed Tomography (CBCT)
In most implant cases, a 3-D X-rays is the gold standard when used for evaluation of implant placement and nerve anatomy evaluation.. To decide the ideal location and measurement parameters associated with the dental implant placement, the implant dentist must be able to accurately measure the distance between the alveolar crest and the superior border of the mandibular canal. Also,, the width of bone in the proposed implant site must also be evaluated. Medical Slice Computed Tomography (MSCT) and Cone Beam Computed Tomography (CBCT) images are the most accurate X-ray modalities in the assessment of available bone and identification of the mandibular nerve.
“CBCT 3D imaging has given our office a distinct advantage over other dental practices in terms of diagnosis and treatment planning.”
Michael Nugent DDS
The use of CBCT radiographs have become more common in the dental office due to volumetric bone imaging, lower equipment cost and immensely lower radiation doses when compared to MSCT. CBCT technology also allows dentists to avoid all the problems of Panoramic 2-D X-rays. In these areas, CBCT has become the leading method for evaluating anatomical structures related to implant planning because it ensures safe and accurate implant positioning. MSCT and CBCT do not magnify or distort structures. Thus, precise measurements of bone levels and vital anatomy are possible.
The quantity of information in CBCT scans compared to conventional x-rays is very different. In order to view 3-D information, the raw data needs to be loaded into a 3rd party software program. The image can then be viewed slice-by-slice using cross-sectioning tools in Axial, Sagittal and Coronal planes. Conventional dental x-rays produce images on film, paper, or computer screen. The conventional x-ray images cannot be sectioned or viewed in any other plane other than the one it is taken in. However, computer software is applied on the Cone Beam CT volumetric data to produce a stack of 2D grey scale level images of the anatomy. The compact size and relatively low radiation dosage of the Cone Beam CT scanner makes it perfectly suited for imaging in dentistry. Cone Beam Computed Tomography is rapidly becoming the “standard of care” for dental implant placement.
Cone beam 3-D x-rays allow for:
- 3-D observation of overall oral/facial bony characteristics, allowing easier diagnosis and placement of dental implants
- Surgical guide fabrication for implant placement
- 3-D observation of teeth for endodontic diagnosis and treatment
- Diagnosis and treatment of tooth impactions (especially wisdom teeth)
- Identification of inferior alveolar nerve and mental foramen location
- Identification of the location of the maxillary sinus
- Identification of the presence of bone lesions
- Analysis of temporomandibular joint characteristics leading to diagnosis and treatment
- Trauma evaluation and treatment
- Integration with CAD/CAM devices for fabrication of prosthodontics or orthodontic appliances
- Identification for referral of numerous conditions or diseases not normally within the realm of dentistry, but that can be shown on typical cone beam images
Video showing the power of Cone Beam CT and Dental Implant Planning.
“Conebeam scans create highly accurate 3-D images of the patient’s anatomy from a single, low-radiation scan. CBCT technology delivers a comprehensive understanding of the patient’s jaw and the anatomical structures necessary to properly provide implant treatment. In other words, CBCT generated images provide detailed information that 2-D radiographs cannot offer. This greatly aids in precision, which improves the entire dental implant process.”
Michael Nugent DDS
Planning the Dental Implant before the Surgery:
Dr. Nugent uses interactive treatment planning software to evaluate and plan the dental implant position prior to surgery. The CBCT data is a true 1:1 (no magnification) representation of anatomy. Thus, Dr. Nugent has the ability to “digitally” place implants, measure available bone, determine angulation, evaluate bone density, and even order surgical guides directly from the computer software. The integration of 3-D data with dental implant treatment planning software allows Dr. Nugent to accurately access the size, type, and ideal placement of the dental implant in relation to anatomical structures PRIOR to surgery. There is no guess work at the time of surgery as everything has been determined. More accurate planning yields a quicker and easier implant surgery for the patient.
Benefits of Cone Beam for Dental Implant Planning and Placement
1. A Cone Beam CT Scan (CBCT) allows Dr. Nugent to select the right size dental implant for optimal tooth longevity. The success of implants require the largest integration and stability in the bone. CBCT enables Dr. Nugent to digitally measure the available bone and select the tallest and widest implant appropriate for the site. This maximum bone utilization will help support chewing forces. Dental implant size selection should not be guesswork! Dr. Nugent uses his 3-D x-ray to predetermine the patients implant prior to surgery. This digital implant placement allows Dr. Nugent to choose the based on precise measurements, bite scheme, biological requirements, and individual patient needs.
2. On the lower jaw, Dr. Nugent uses the CBCT data to trace the path of the mandibular nerve and choose the most appropriate length of dental implant. Old fashioned X-rays are flat and distorted and are a poor choice when trying to pinpoint the location of the jaw nerve. Permanent nerve damage from dental implant placement is possible. Therefore, it is vital to know EXACTLY where the nerve is in order to avoid any complications. CBCT is a needed imaging technique to prevent this serious implant complication.
3. On the upper jaw, CBCT shows Dr. Nugent a precise image of the maxillary sinus and its position in relation to the available bone. Dr. Nugent can then take accurate digital measurements in order to select the right implant length to avoid perforating the maxillary sinus. Old fashioned X-rays are highly inaccurate when trying to determine where the floor of the maxillary sinus is.
4. A CBCT allows Dr. Nugent to correctly analyze the available bone. With advanced 3-D software, Dr. Nugent will digitally place a virtual implant. This allows Dr. Nugent to place the implant is the maximum amount of bone
5. Dr. Nugent can merge CBCT date with CEREC data to get a complete picture of the soft and hard tissue of the patient. This prevents crooked implants, which may be difficult or impossible to restore, and avoids poor cosmetics and function.
Comparisons of Medical Grade CT Scans to Cone Beam 3-D Technology:
There are multiple advantages of Cone-Beam Technology (as applies to facial skeletal imaging) compared with medical grade CT scans:
- Significantly lower dosages of radiation are delivered to the patient by Cone Beam CT scans. The dosage of radiation received with certain types of Cone Beam scans is only slightly higher than that obtained with a Panorex film.
- Convenience. These scans can be obtained while in the Oral Surgeons office, thereby eliminating the need for transport of the patient to a hospital or imaging center. As the images are generated within several minutes, there is no delay to the patient or surgeon in obtaining the images.
- Multiple anatomic regions can be assessed 3-Dimensionally in one scan-eliminating the need for multiple PA and/or panoramic (or tomographic) images. Both upper and lower jaws are scanned at the time, eliminating the need for additional exposures.
- Lower costs to the patient-reformatting of data are eliminated with certain cone-beam technologies, eliminating this out-of pocket costs for patients.
- Accuracy-as mentioned above, due to the small voxel size of this modality, accuracy is generally stated to be within 0.1mm superior to that of medical grade scans.
Cone Beam CT scans represent a new imaging modality, these scanners allow excellent visualization of facial skeletal anatomy but at significantly lower radiation dosages than medical-grade CT scanners