Can Dental Implants Fail When There Is Excess Stress?
From the investigation of dental implant models as per current dental research, it is important for the dental implant specialist, implantologist, or maxillofacial surgeon performing the surgical procedure to consider several factors that influence the stress concentration areas in the alveolar bone where the implant is placed. Factors such as bone density, implant shape, length, diameter, and surface modifications play a crucial role in how stress is distributed within the surrounding bone tissue. Moreover, the alignment and positioning of the implant can also impact the load transfer and influence its success. A well-placed implant ensures better stress distribution and minimizes the risk of micromovements, which can compromise osseointegration (bone and implant integration process).
Additionally, incorporating advanced imaging techniques, such as cone-beam computed tomography (CBCT), can assist in visualizing the bone architecture and identifying any anatomical variations that may affect implant placement. Understanding these variables allows the dental professional to make informed decisions, thereby enhancing primary stability, promoting faster healing, and reducing the chances of implant failure.
How Does Stress Concentration Impact the Success Rates or Outcomes of Dental Implants?
Dental researchers indicate that the level of stress a dental implant experiences in toothless patients, particularly at the implantation site, significantly affects its primary stability. This primary stability refers to how well the implant has fused with the jawbone (upper or lower), as osseointegration plays a crucial role in determining this stability.
What Factors Help Reduce Stress Concentration on Dental Implants?
Here are the key findings from various studies on the stress-bearing capacity of dental implants in both animal and human models, highlighting the importance of evenly distributing stress across natural teeth or other prosthetics, rather than relying solely on the implant, to prevent biological or prosthetic failures.
-
Research authors indicate that during the loading of a dental implant, the highest concentration of stress is typically observed around the cortical bone, that is, where the upper part of the head of the implant fuses or integrates into the bone. Irrespective of the implant length diameter or width, this critical area, the cortical part of the bone—needs to be preoperatively assessed to increase primary stability, improve success rates, and prevent prosthetic failure. Preoperative evaluation using multidetector CT scanning, CBCT scanning, or sectional bone analysis at the implant site can provide valuable insights for the dental operator. It helps in designing and considering the bone density and strength in this cortical region, thereby enhancing primary stability and increasing the chances of proper bone-implant contact or osseointegration.
-
Almost 83 percent of research studies indicate that higher stress concentrations can occur with the use of short-term implants, while long and thin implants generally tend to cause much less displacement during implant loading protocols. From the perspective of the bone-implant interface, to avoid excessive stress on the underlying alveolar bone, implant length is an effective parameter that should be considered to dissipate masticatory or chewing forces in patients with dental implants. According to dental researchers, cortical bone is only one factor to be considered by implant specialists during dental implantation. However, the next layer of trabecular bone is also critical, where the threads of the dental implant should effectively fuse. This is the parameter where implant length significantly determines success. Long and thin implants generally work well in conjunction with trabecular bone density, enhancing the biomechanical performance of the prosthesis, which can significantly reduce stress concentration on dental implants.
-
According to the fundamental principle outlined by Revered Misch et al., who in their publications mentioned that force or surface area is equal to stress. This principle indicates that total stress concentration on the implant prosthesis can be reduced by increasing the total surface area rather than merely increasing the bone-implant contact area. According to current protocols, increasing the diameter of dental implants, especially when there is sufficient bone width or adjacent space to accommodate the prosthesis, can lead to a higher bone-implant contact area (BIC). This means that stress forces will dissipate more effectively, and the overall mechanical stress borne daily by your dental implants can be reduced significantly. This subsequently leads to enhanced primary stability, a lower chance of displacement under higher torque or stress-bearing forces, and thereby improved long-term success rates.
-
Bone Quality: Higher density D1 and D2 bone types are reported to have greater success rates for dental implants in patients. More implant failures have been documented in weak-density D4 bone, commonly found in the posterior regions of the maxilla (upper jaw), which is why this segment often requires sinus rehabilitation, sinus lift surgery, and bone augmentation in many documented cases to achieve sufficient bone depth and density. In some patients, where D3 or D4 (that is, lower-density bone) is present in the implant area, whether, in the maxillary or mandibular (lower jaw) region, the risk of implant failure is higher because bone density is a major factor influencing stress dissipation and primary stability.
-
Cervical Anchorage: During the initial phase or healing period of dental implants, the current protocols recommend that dental operators avoid exerting oblique forces on the loaded dental implants to achieve better stress dissipation. This means that implant design, the load-bearing capacity of the cortical and trabecular bone, and the decision between immediate or delayed implant loading protocols are all indirect determinants of anchorage within the bone, specifically, cervical anchorage of the implant in the jaw, to promote or enhance successful outcomes.
Conclusion
Proper stress dissipation can significantly benefit long-term implant success rates in the jaw. The factors listed above are outlined by current dental research to prevent excessive stress on the implant prosthesis. However, additional factors are currently being investigated and require more evidence, such as implant thread design, platform switching, screw pitch, and the biomechanical performance of different implant-based manufacturing systems.
