Introduction:
The osseointegration process or phenomenon of the dental implant determines the long-term success rates in the implant patient. Hence the oral surgeon or the implantologist often adopts crucial choices that may deviate from conventional implant surgery and prosthesis at times, be it by bone augmentation, regeneration, under preparation of the implant osteotomy site, or selecting a specific implant diameter, length, or thread design that varies from patient to patient.
What Are the Evolutionary Variations and Development of Jaw Bone Density?
The average bone density is not uniform throughout the jaw and varies at different positions that depend on our dentition, the masticatory, and jaw forces. For the stabilization of dental implants, bone density is an essential factor that influences osseointegration success. According to traditional medical research, the different bone densities within the maxillary and mandibular arches are related to human evolutionary pressures within the cranium region of our skull to keep it light at a sufficient pace. This may also be according to widely understood theories of evolution. The numerous developments prenatally and postnatally eventually transformed the facial skeleton and skull bones. The earliest observations in implant dentistry are interlinked to the understanding that the maxilla or the upper jaw acts as a force distribution unit, and the mandible or lower jaw acts as a force absorption unit.
Therefore, the changes in bone density or the tooth anatomy, especially in the anterior section of the jaw bones, are as per evolutionary changes. Research upon it indicates that primarily the varying functions of incisors, canines that exert the grinding forces or the comparatively sharper incisal edges, are responsible for the anterior bone density changes. Also, because the functionality of the anterior teeth is mainly for food tearing and cutting purposes, these teeth withstand lateral displacement forces that require more resistance to stress, strain forces, and more bone support primarily.
Conversely, when the posterior teeth anatomy is considered, i.e., the premolars and molars, these masticatory forces laterally are reduced. In contrast, the vertical chewing forces for food (masticatory forces) are more. Also, compared to the male and female patients, a significant difference is noticed more in the males with a thicker or higher bone density. In numerous clinical trials and traditional dental implant research, the surveys indicate that male patients had much higher bone density than female patients. Similarly, female patients tend to exhibit a difference in the denser cortical bone than males. While age does not remain a question in terms of predicting bone density, in terms of gender, these differences in bone density may be due to specific anatomic regions that compose the trabecular bone.
What Are the Bone Density Measurement Methods?
The most reliable bone density measurements to accuracy can be obtained thus by the following methods :
A. CT Bone Density Measurements - Through CT scan, the radiographic data can be collected in Hounsfield units that utilize a calibrated scale to objectively measure the jaw bone density. However, in recent decades, the concerns of radiation exposure to the patient have now been addressed by dentists across the globe with the advent of CBCT technology (cone-beam computed tomography).
B. CBCT - Cone beam computed tomography has shown to be very clear in three-dimensional assessment and planning preoperatively and has limited radiation exposure to the patient. Hence, this technique effectively helps dental implant treatment planning, assessing bone density, and assessing the position of the surgical template guide used for correct implant position and placement to prevent angular deviations or operator-based errors.
C. DEXA (Dual-Energy X-Ray Absorptiometry) - This technique is extremely advanced with its advent for measuring the bone mineral density, though its measurements are purely two-dimensional. However, like any other 2d imaging modality, this makes it prone to bone artifact errors.
D. Accessory Methods - Other newer methods by advances in implant dentistry include histomorphometric measurements, application-based techniques upon the Archimedes principle, or the other technique introduced being biopsy assessment through micro CT. However, these techniques may not be effective in measuring the bone mineral density compared to the modalities of CT and CBCT and are used as an option available in non-clinical settings because they are also invasive radiographically and may be prone to technical or radiographic errors.
E. Advances in Measuring BMD - The recent advent in implant dentistry by the use of specific torque measuring micromotors is one of the effective techniques that is gaining trend in this field as it enables the operator to measure specific bone density measurements at anatomic regions or particular areas of the jaw just like CBCT and also has an added advantage of quantitatively and intraoperatively aiding in obtaining quantitative data at the specific site. Hence the micromotor-based system is operator dependent and is now considered an advanced, reliable surgical measurement system for bone density.
Role of Bone Density in Dental Implantation:
Be it for early or immediate loading protocols adopted by the dental implantologist, implant stabilization within the bone or the BIC (bone-implant contact) is considered the most influential factor for achieving primary stability. Therefore, there should be no micromovements or displacement of the fixtures after the implant insertion to accomplish the same. This can lead to bone loss or inflammation (peri-implant mucositis and peri-implantitis). In addition, after the displacement exceeds a particular threshold, the implant tends to be mobile, or eventually, it can fail because these displacing forces hinder osseointegration within the trabecular bone.
Conclusion:
To conclude, though patients seek implant-supported restorations and dental implants to replace the missing teeth as a long term esthetic and functional option, the dental implantologist should assess the bone density preoperatively because of the variation in trabecular bone density based upon the anatomic region, site, and the patient-related factors discussed. Hence, the treatment options for dental implantation and prosthetic replacement should be customized and planned accordingly by a thorough pre-operative assessment of bone density.
