The aim of the diagnostic accuracy study was to compare the diagnostic accuracy of probing depth before (PPD-1) and following (PPD-2) the removal of prothesis in identifying the presence of peri-implantitis and assess the factors influencing peri-implant probing.

This study aims to design a diagnostic accuracy study to compare the peri-implant probing depth and bleeding on probing before and after crown removal. It will explore the impact of prosthetic design on the accuracy of peri-implant probing and its diagnostic accuracy, and provide clinical recommendations on whether the prosthesis should be removed prior to peri-implant probing.

Inclusion Criteria:

1. Age greater than 18 years.
2. The implant has completed osseointegration and has undergone final restoration for at least one month.
3. The final restoration needs to be removed or retrieved for various reasons.

Exclusion Criteria:

• Patients with serious systemic diseases, severe intraoral infections, severe mental disorders, pregnancy/lactation in women, or other conditions that make oral treatment operations unsuitable.
• History of crown removal or re-restoration within the past month prior to the visit.
• The prosthesis has fallen off or is severely damaged and has lost its original form before the visit.
• The prosthesis cannot be completely removed.
• Refusal to participate in this study.

For this study, the calculation was estimated considering the peri-implantitis prevalence at implant level, thealternative the area under the receiver operating characteristic curve 0.90 , a 5% alpha error and 90% power. Thus, the minimum required sample size was 83 subjects.