The goal of this observational study is to compare the prevalence of peri-implantitis between periodontitis and nonperiodontitis sites treated with alveolar ridge preservation.

The main question it aims to answer is:

• whether the occurrence of PI is associated with reasons for dental extraction because of periodontitis and nonperiodontitis after alveolar ridge preservation.

Researchers will compare the prevalence of peri-implantitis between periodontitis and nonperiodontitis sites treated with alveolar ridge preservation.

Inclusion Criteria

1. patients aged ≥ 20 years
2. patients who required tooth extraction and implant therapy
3. at least two bite-wing radiographs: baseline and at least a 6-month follow-up

Exclusion Criteria

1. a medical condition as a contraindication to dental surgery, autoimmune disorder, immunosuppression, or uncontrolled diabetes (HbA1c > 7%);
2. ong-term nonsteroidal anti-inflammatory drug use
3. oral bisphosphonate therapy
4. pregnancy or lactation
5. the absence of follow-up bite-wing radiograph
6. cigarette consumption >10 per day
7. a history of head and neck radiotherapy.

We enrolled consecutive patients who received dental extraction and ARP simultaneously and dental implant treatment at least 4 months after ARP at the Division of Periodontics, Kaohsiung Medical University Hospital