Introduction
Dental implants have revolutionized modern dentistry, offering patients a reliable solution for missing teeth. However, the success of dental implants can be hindered by foreign body reactions (FBR), a complex biological response that can compromise implant stability and overall oral health. Foreign body reaction after dental implantation is a pathologic process that can pose a great risk to the stability of the dental implant in the jaw and prevents osseointegration by inducing a series of unfavorable chain of events in the surrounding soft tissue.
Which Individuals Are More Prone to a Foreign Body Reaction?
Dental implants are the most stable and effective prosthetic options for individuals seeking long-term rehabilitation of missing teeth or tooth. In most successful cases, dental implants osseointegrate (fuse with the jaw bone) within a period of three-six months. However, when this osseointegration process is disrupted by local or systemic factors, it may result in 'fibro-osseous' integration or the formation of connective tissue around the implant instead of bone. This can lead to long-term dental implant instability or failure.
Unhealthy or fibro-osseous integration commonly occurs when the implant undergoes a foreign body reaction (FBR) instead of the ideal fusion with the jawbone. Dental researchers suggest that the implantation of any foreign material in the oral cavity, similar to other parts of the body, could trigger an inflammatory or fibrotic process known as the foreign body reaction (FBR). Several factors, such as local trauma, irritation, poor oral hygiene, smoking, or systemic factors like immunocompromised states (in which dental implants are usually contraindicated), intake of specific medications, or underlying systemic issues like type 2 diabetes, hypertension, hyper or hypothyroidism, endocrinal disorders, can contribute to an individual developing a foreign body reaction to the implant.
What Is the Pathogenesis of Foreign Body Reaction?
The etiopathogenesis of FBR or foreign body reaction to dental implants can be explained by researchers as follows :
Upon dental implantation into the tissue, immune system cells may be attracted to the foreign material while simultaneously attempting to degrade the implant surface. If the degradation of the dental implant surface fails, fibroblast cells may envelop the implant material, forming a physical barrier and isolating it or treating it as a 'foreign body' or object from the rest of the body. Although the foreign body reaction may indeed be an unavoidable process that occurs with dental implantation, by following certain precautionary measures the dental implantologist or implant specialist can reduce the risk of FBR.
What Are the Phases of Foreign Body Reaction?
There are mainly two phases of FBR that occur over a period of a few weeks to months after dental implantation:
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Acute or predominantly inflammatory phase
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The chronic or fibrotic phase
Both these phases may pose not only significant challenges to the integration of the dental implant but may also interfere completely with its therapeutic function, leading to instability, mobility, deteriorated soft tissue health around the implant (peri-implant inflammation or peri-implantitis), and an increased risk of long-term mobility and prosthetic failure.
- Acute Phase: The acute phase may begin immediately after dental implantation. The tissue damage or blood extravasation occurring locally triggers the inflammatory-mediating cells to the area of implantation. Proteins found in extravasated blood, such as albumin and fibrinogen, then get adsorbed to the implant surface. This phenomenon is known as the Vroman effect, which occurs during the acute phase of FBR.
- Chronic Phase: The chronic phase of FBR is mainly characterized by a fibrotic process occurring after the initial inflammation around the dental implants. If the dental implantologist or surgeon does not follow up or treat the local inflammation surrounding the implants due to a possible FBR in the acute phase, it may advance to the chronic phase of a fibrotic process.
When Does Prosthetic Failure Occur?
The implant dentist should be aware that while there is a direct clinical challenge posed to the survivability of the dental implant in the acute phase itself, the chronic stage of FBR may worsen the long-term prognosis of dental implants. In the chronic phase, there may commonly be encapsulation of the implant in a layer of fibrous tissue (fibroosseous integration). This fibrotic layer acts as the main barrier that interferes between the implant and the host tissue.
During the chronic phase of FBR, the transition into its fibrotic stage occurs progressively over several weeks after implantation. This means that in the chronic phase, the survivability of the dental implant is significantly compromised and it would need to be removed by the dentist; otherwise, it may cause severe soft tissue infections locally, destroying the peri-implant tissues. The chronic phase of a foreign body reaction in the oral cavity, especially concerning dental implants, is considered a prosthetic stage failure and requires implant elimination at the earliest.
What Are the Measures Taken by Implantologists and Dentists to Prevent Foreign Body Reaction?
The measures that can be adapted to prevent foreign body reactions or minimize the risk of implantation trauma are as follows:
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Implant Design: Dental implants should be designed taking into consideration the type of surgical implantation procedure, such as immediate implantation or conventional implantation post-recovery from an atraumatic extraction. Implant designs could incorporate biodegradable or material shanks that enable easy penetration into the jaw tissue. Such implant surface designs would not only simplify the dental implantation procedure but also eliminate the need for the implant dentist to use bulkier surgical tools, reducing tissue damage.
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Flexible Implants: These can be pre-designed or combined with specifically designed shuttle tools to lower trauma at the site of dental implantation into the local tissue.
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Implant Biomechanics: With the current progress and advancements in dental implant manufacturing, dental implant manufacturers usually consider the biomechanics of the dental implantation procedure and design the surface to minimize the risk of tissue trauma. This design also enables the operator to have ease of surgical handling, reducing implantation trauma and the development of a foreign body reaction.
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Imaging-Guided Implant Materials: It is commonly known as imaging-guided implantable materials, and are chosen based on pre-implantation studies conducted by dental implantologists or dental implant specialists. These materials need to be selected to avoid any potential toxic elements that could cause damage to the host tissue or promote local inflammation.
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Surgical Systems: Surgical systems should always be used instead of manual instrumentation by the operator to avoid injury to major blood vessels or reduce blood extravasation during the implantation procedure.
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Material Selection: Over many decades of ongoing research in the field of implant dentistry, selected dental materials are now being used that exhibit good biocompatibility with jaw tissue, including polymers, silicones, polyethylene, polyimide metals, and ceramics, among others.
Conclusion
Foreign body reactions (FBR) following dental implantation can disrupt stability and osseointegration, leading to complications. Triggered by factors like local trauma and poor oral hygiene, FBR occurs in acute inflammatory and chronic fibrotic phases. Dentists employ strategies such as thoughtful implant design, flexible implants, advanced manufacturing techniques, material selection based on studies, and surgical precision to prevent FBR, ensuring the long-term success of dental implants
