Dental Implant Failure

Introduction

The complete loss of function of the dental implant is denoted as dental implant failure. These dental implants are being placed to restore and mimic the role of teeth, and hence it is advised in missing teeth conditions. In order to ensure the success of every dental implant, certain factors like oral hygiene status, general health status, bone strength, and bone density should be promptly assessed beforehand. A thorough evaluation of the implant prognosis should be made to check implant failures. However, there are chances for dental implants to fail. Any form of infection involving the dental implant can influence the fusion of the implant with the underlying bone and subsequent failure of the implants. The failed dental implants often elicit soreness, swelling, and redness encircling the implant area. In addition, the patient may experience loss of stability of the implants.

According to the dental surgeon or implantologist, the key factor for a successful implant is the right or appropriate patient selection suitable for an implant prosthesis. Like all surgical procedures, a dental implant procedure can be performed only after verifying the patient's medical and dental history in detail. Similarly, there are certain risk factors or exclusion criteria identified by surgeons to rule out an implant prosthesis in some patients. Likewise, there are also absolute contraindications in certain systemic diseases wherein the implant, instead of fusing with the underlying jaw bone (osseointegration), fails or gets integrated into the connective tissues (fibro-osseous integration).

What Are the Exclusion Criteria or Contraindications?

Patient Selection - The patient selected for a dental implant has to be free from these criteria for the dental implant to be successful in the long term.

The exclusion criteria usually considered by dental implantologists are in regard to any patient who requires a single or two or multiple implants, and it is supported by the crown prosthesis. The general contraindications for implant placement are,

1. Immunosuppressed or immunocompromised patients.

2. Uncontrolled diabetes.

3. Pregnant and lactating women.

4. Substance abusers.

5. Psychiatric disorders.

6. Irradiation in the head and neck areas.

7. Acute local infection or suppuration (pus) at the site of implant placement.

8. Patients with a previous history of intravenous bisphosphonates or patients undergoing bisphosphonate therapy.

9. Untreated periodontal disease or periodontitis.

10. Poor oral hygiene and patients with lack of motivation towards oral hygiene.

11. Patients with unrealistic expectations (by appearance, form, or function as an implant can only serve these three purposes similar to a natural tooth in comparison).

12. Active cancer therapy or cancer patients.

13. Recent valvular prosthesis or transplantation cases (less than 6 months).

14. Recent history of myocardial infarction or cerebrovascular incidents (less than 6 months).

15. Patients with blood disorders or high bleeding risk cases with high platelet count.

What Are the Risk Factors and Success Rates for Dental Implants?

Apart from these general contraindications, which may often be considered "absolute" risk factors for implant placement by the operator or surgeon, the following are the other accessory risk factors that can also impair the wound healing and integration of bone and implant surface. Hence these risk factors will need to be attended to before proceeding to dental implantation surgery.

1. Heavy smokers have an absolutely altered oral immune physiology that leads to implant failure. Hence counseling and guidance are essential by the physician or dentist before implantation to quit smoking completely. Moderate smokers or occasional smokers will also need to follow strict quitting as any relapse of the addiction can impair the wound healing process after implantation.

2. In patients with low bone density, either due to local infections or dental disease, the cause needs to be thoroughly treated by the dental surgeon first. After the local issue is managed, if bone grafts need to be placed to compensate for the lost or resorbed bone, then a bone graft procedure is necessary. Autologous bone grafts (from the patient's own body) can be harvested from various anatomic sites like the mandibular symphysis, anterior or posterior iliac crest, retromolar area, coronoid process, calvarium, tibia, ribs, etc.

3. In patients who are on medications for systemic diseases and who are controlled in their levels for the respective disease like hypertension, diabetes, or past history of radiotherapy, even then there is a risk of soft tissue impaired healing or fibrotic scarring or necrosis (cell death) of the local area of implant placement. If extensive and appropriate measures are taken by the operator or dental surgeon while carefully implanting and producing the crown prosthesis by regular bone check and x-ray. In that case, these patients may also have a long-term success rate.

4. Very rarely but quite possible also when the operator errs while surgical procedure like the improper design of the flap incision, insufficient mobilization of the mucoperiosteal flap, or excess pressure created by temporary prosthesis over the implant screw can have a negative effect on the wound healing and hence lead to failure.

How Do You Know an Implant Has Failed?

The implant prosthesis is considered a failure only when the implant crown or framework needs to be replaced by an alternate prosthesis. Whereas if the implant itself shows mobility, progressive soft tissue, or bone loss around it with time or any infection that is localized, then the implant itself is considered a failure. There are mainly two kinds of complications that can be identified with prosthetic or implant failure post-implantation. They can be classified into,

1. Mechanical Failure - Associated mechanical complications are,

• The fracture of the prosthodontic component of the implant crown after or within a few months.
• Loosening of the crown.
• In the case of multiple abutment prosthetic frameworks, the fracture or detachment of the resin teeth.

2. Biologic Failure - Associated biological complications are,

• Peri-implant mucositis (heavy inflamed soft tissue without bone loss).
• Peri-implantitis (bone loss with suppuration and heavily inflamed soft tissue).
• Patient-reported complaints like the occurrence of fistulas or sinusitis.

What Are the Pre and Post-Operative Management to Be Followed to Avoid Implant Failure by the Dentist?

These measures need to be implemented effectively pre and post-implant procedures to avoid the dental implant's surgical, prosthetic, or biologic failure. Though each dental surgeon varies in their approach, some of the common preventive modalities followed are,

1. Before implant placement, patients are usually counseled by the dental surgeon or implantologist to follow strict oral hygiene and seek dental help for any other dental issues the patient has that are pending so that it does not hinder or be a cause of concern after implantation.

2. One hour prior to the implant procedure, some dental surgeons advocate the use of professional oral prophylaxis and prophylactic mouth rinse with 0.2 percent Chlorhexidine antiseptic mouthwash for a minute. Prophylactic antibiotic therapy (Amoxicillin one to two grams or Clindamycin 600 milligrams if allergic to Penicillin) can also be initiated prior to implant surgery.

3. Following implant placement, instructions for oral hygiene and diet, and sutures, if they need to be placed, are given by the dental surgeon. Four to six months, preferably after placement, definitive impressions can be taken using customized open tray or closed tray techniques. The dentist makes occlusal adjustments after the prosthesis is fabricated (either cement or screw-retained restorations). Patients are supposed to follow up 6 months after implant prosthesis is successfully given for occlusion control and monitoring of implant stability and health.

Conclusion

Dental implant failure is often driven by multiple contributing factors. When proper selection criteria and surgical prosthetic management protocols are followed by the dental operator, the chances of implant failure are limited. The patient's oral hygiene, habits, and systemic status are crucial to the long-term success of the implant restoration. Reimplantation strategies are also employed in cases with obvious signs of dental implant failure.