Why Is Bone Mineral Density an Essential Determinant of Implant Success?
The increased use of dental implants is one of the major dental revolutionary trends in current practice, as dental implants have now replaced crowns, bridges, and dentures for being called or touted as the ideal prosthetics for replacing missing teeth because they can at best ideally, restore function as well as esthetics, as close as possible to the natural teeth. This is one of the fundamental reasons behind any edentulous (missing of all the teeth) or partially edentulous (presence of only a few teeth) dental patients opting for dental implant prosthetics as the first choice and gold standard of treatment to gain back the near natural efficiency and form, which can at least be a pale imitation of the natural tooth lost. However, as one may be well aware, not all dental cases or patients may be suitable for dental implantation because there are several exclusion and inclusion criteria for the dentist to consider, such as prosthetic options that may or may not be suited to the patient. By thorough pre-operative evaluation and assessment of bone mineral density (BMD), the dentist will provide a clinical picture and the possibility of what would best suit a prosthesis.
The bone mineral density is always assessed preoperatively before the dental implant surgery by the implant dentist or maxillofacial surgeon, and it is important to note that this is one of the major factors as well that can determine post-operative prosthetic success. This indicates that the bone mineral density at the site of dental implantation, whether in the upper or the lower jaw, is one of the major determinants of the primary stability of the implant that would be placed. The higher the primary stability and the torque control of the dental implant by the implant dentist or the oral surgeon, the higher the post-operative success rates. In short, it can ensure the long-term survival rates of dental implants without any cause for implant failure.
What Are the Different Methods Used to Determine Bone Mineral Density?
Because this factor remains one of the most crucial for the success of dental implants, various methods of diagnosis and analysis have been suggested by maxillofacial surgeons and implant dentists over the decades, with the advent of implant dentistry radiographic modalities like CBCT (computed beam tomography) being a major beneficial modality in analyzing the patients bone quality and even in sectional analysis. While simple panoramic radiography or OPG (orthopantomogram) and intraoral periapical radiographic modalities were the major ways to determine bone density in the olden days, with the advent of CBCT, a major revolutionary trend has set in current dentistry for detailed and clear visual analysis of the patient's jaw.
Usually, the bone mineral density or BMD in the lower jaw is determined by the implant dentist or oral surgeon referring the patient to a physician, where the bone mineral density in the lumbar vertebrae and femur would be measured using DEXA scans (dual-energy x-ray absorptiometry scan). Similarly, as mentioned, the implant dentist does not need to rely on the DEXA scan because most surgeons directly analyze or diagnose dental diseases and bone quality through CBCT.
What Are the Advantages of MDCT Over the Drawbacks of DEXA and CBCT?
The drawback with both these measurements in bone density is that the oral surgeon may not have any detailed evaluation of morphological abnormalities or changes in the jaw. Further, in the case of DEXA, it is only presumed that the lower jaw bone density would be similar to that of the lumbar vertebrae and the femur bone. With more current advances and research being performed in the field of implant dentistry, quantitative CT scan (QCT) is one of the new age and trending dental radiographic modalities for analyzing bone morphology as well as detail in a clear picture. This QCT procedure is performed with the help of multidetector CT, also called in short as MDCT.
To summarize, QCT, in combination with MDCT, is currently a feasible and accurate method for diagnosing bone mineral density in dental implant cases by the maxillofacial surgeon or implantologist. MDCT (multidetector computed beam tomography) can overcome both the limitations of just studying the jaw morphology as well as the drawbacks with DEXA, which relies on the assessment of vertebrae. In multidetector computed beam tomography or MDCT, the quantitative CT technique will measure the maxillary and mandibular (upper and lower jaw bone) jaw bone in Hounsfield units or HU values.
How Is the Bone Density Assessed Through MDCT?
A precise and objective quantification or assessment of bone mineral density is a much-needed practicality in modern-day implant dentistry that offers the maxillofacial surgeon or implant dentist accurate guidance and information on how best to meet the functional and esthetic expectations of the patients from their dental implant prosthesis. Ranging from the classification of D1 bone (a uniform density compact bone) to D5 bone (calcified but incomplete soft bone), there are varying bone densities that should be assessed at the site of dental implantation. In the case of MDCT technology, this objective and quantifiable information would be more feasible and accurate to the implant dentist. According to dental implant research specialists, bone density that is identified in the jaw in the HU (Hounsfield units) values can help in classifying the D1 to D5 range bone density classification as well:
- D1 or high-density bone that would be suitable for dental implantation usually exceeds 1250 HU.
- D2 or good density bone that would be a suitable density for dental implants ranges in between 850-1250 HU.
- D3 or medium-density bone would be an operator-dependent decision for dental implantation with precautions between 350-850 HU.
- D4 or low bone density bone would be a high-risk and unsuitable zone except for patients in the inclusion criterion or suited for dental implants ranging in between 150-350 HU.
- D5 or weak or extremely low bone density can cause possible dental implant failure ranging from less than 150 HU.
Conclusion
Multidetector computed beam tomography or MDCT utilizing the QCT method can be an excellent and feasible three-dimensional radiographic imaging modality measuring in HU units compared to other conventional BMD methods like DEXA and CBCT scan. Its capability to differentiate between trabecular and cortical bone densities offers a comprehensive view of bone health. Along with its diagnostic accuracy and treatment efficacy monitoring, MDCT is a valuable tool in modern radiology practice.
