New implant prognosis model predicts five-year outcomes with high accuracy
Validated five-year prognosis model helps identify high-risk implants at baseline; practical for case planning and patient communication.
A structured framework for implant risk assessment
Researchers have validated a new implant prognosis system that integrates multiple clinical and systemic factors to predict medium-term implant survival. Unlike earlier models focused solely on bone loss or disease stage, the Kwok et al. system evaluates plaque control, implant position, restoration design, periodontal history, supportive care, smoking, diabetes, osteoporosis, antiresorptive medicines, radiotherapy, occlusion and genetic factors. Implants are classified into four prognostic categories: favourable, questionable, unfavourable and hopeless.
Clinical validation shows clear risk stratification
A retrospective analysis of 651 implants in 291 patients over five years demonstrated the system's predictive capacity. Implants with a favourable baseline prognosis achieved 100% survival, compared with 93.5% in the questionable group and 33.3% in the unfavourable category. Baseline prognosis remained unchanged for 95.7% of favourable cases, 78.5% of questionable cases and 33.3% of unfavourable cases over the study period. The model showed stronger predictive reliability for mandibular implants than maxillary implants, with anterior and premolar sites in the mandible more consistently assessed than molar sites. In the maxilla, prognosis was reliably predictive only for central incisors.
Framework has potential but requires refinement
The authors acknowledge the system may be incomplete and suggest future versions consider implant phenotype, detailed prosthetic factors, mandibular versus maxillary location, and antidepressant use as possible prognostic modifiers. The structured approach allows clinicians to stratify patient risk, identify high-risk cases earlier and communicate treatment outcomes more accurately. The study was published online 6 March 2026 in the Journal of Periodontology.
Frequently asked questions
What factors does the Kwok implant prognosis system evaluate?
The system assesses plaque control, implant position, restoration design, history of periodontitis, supportive care, smoking, diabetes, osteoporosis, antiresorptive medicines, radiotherapy, occlusion and genetic influences. It classifies implants into four prognostic categories: favourable, questionable, unfavourable and hopeless.
What five-year survival rates did implants achieve in each prognosis category?
Implants with a favourable baseline prognosis showed 100% survival, questionable 93.5% and unfavourable 33.3% over five years. Baseline prognosis remained unchanged for 95.7% of favourable cases and 78.5% of questionable cases.
Is the prognosis model equally accurate for mandibular and maxillary implants?
No. The model showed stronger predictive reliability for mandibular implants. In the mandible, anterior and premolar sites were more reliably assessed than molars. In the maxilla, prognosis was reliably predictive only for central incisors.
What improvements do the authors suggest for future versions?
The authors recommend future versions consider implant phenotype, more detailed prosthetic factors, implant location differences between mandible and maxilla, and possible antidepressant use as prognostic modifiers to improve accuracy.
