Part 1:
Inclusion Criteria:
1. Patients who had fully-erupted first molar extraction (tooth number #3 or #14 or #19 or #30) under Code on Dental Procedures and Nomenclature (CDT) code of D7140 (Extraction, erupted tooth or exposed root) and D7210 (Extraction, erupted tooth requiring removal of bone and/or sectioning of tooth, and including elevation of mucoperiosteal flap if indicated) at TUSDM.
2. The electronic records must include the following data:
* Gender
* Age
* Comprehensive periodontal chart, including probing depth (PD), clinical attachment level (CAL), furcation involvement and mobility. The periodontal chart has to be recorded within 12 months before tooth extraction
* Periapical radiograph and bite-wing radiographs of extracted tooth. The radiographs have to be taken within 12 months before tooth extraction
* Reasons for tooth extraction
Part 2:
Inclusion Criteria:
1. Patients who had:
* Fully-erupted first and second molars (tooth number #2, #3, #14, #15, #18, #19, #30, #31) that were extracted under CDT codes D7140 (Extraction, erupted tooth or exposed root) or D7210 (Extraction, erupted tooth requiring removal of bone and/or sectioning of tooth, and including elevation of mucoperiosteal flap if indicated).
* The same extracted tooth were replace with dental implant placement under CDT code D6010 (Surgical placement, endosteal implant) within 24 months after extraction.
2. The electronic records must include the following data
* Sex
* Age
* Dental records including:
* Periapical radiograph of the tooth before extraction: the radiographs have to be taken within 12 months before tooth extraction, including one or more of probing depth (PD), clinical attachment level (CAL), furcation involvement and tooth mobility.
Exclusion Criteria (both parts):
1. Absence of tooth distal to extracted tooth.
a. Clinical decision for tooth extraction may be affected by tooth location. When the tooth is the distal abutment in the dentition, clinicians tend to keep the tooth even if the prognosis is compromised.
2. Presence of dental implant adjacent to extracted tooth a. Clinical decision for tooth extraction may be affected by adjacent dental implants.
