Currently, the investigators are unaware of any previous studies that have analyzed the relationship between the prevalence of thyroid disease and chronic periodontitis among adults utilizing a retrospective, cross-sectional design. This study will review approximately 2000 patient records and compare the prevalence of thyroid disease in three groups with increasing severity of chronic periodontitis.

This is a retrospective, cross-sectional patient records review study. Only records with subjects that were 35 years or older and have been active patients of the School of Dental Medicine, University at Buffalo will be included. Three individual searches with three distinct patient criteria will be conducted to obtain records from subjects in three populations with different degrees of periodontal disease. All subjects that qualify the eligibility criteria will be selected. The IT Department has access to select the subjects according to the eligibility criteria without requiring access to the physical patient record. The three subject groups are:

1. Periodontally healthy patients: Patients with a D1110 or D1111 (adult prophylaxis including those with 6 or fewer teeth) treatment code, seen by a 3rd or 4th year pre-doctoral dental student. Excludes all charts that have ever had a U4990 (Perio case) treatment code. Patient is 35 years or older relative to 1/1/2016.
2. Patients with a history of advanced periodontal treatment, group 1: All patients treated in the Postgraduate Periodontics department by a periodontics resident between 1/1/2000 - 12/31/2017. Patients presenting for treatment of chronic periodontitis will be included while those patients presenting to the clinic for other reasons, such as crown lengthening procedures, will be labeled as such. All patients selected will be 35 years or older at time of initial exam.
3. Patients with history of advanced periodontal treatment, group 2: All patients ever treated in the private faculty practice of one periodontist, that were still active patients during between 1/1/16 - 12/31/16. Only those 35 years and older were included. Patients presenting for treatment of chronic periodontitis will be included while those patients presenting to the clinic for other reasons, such as crown lengthening procedures, will be labeled as such.

All duplicates within a group will be excluded (e.g. patients may have had a D1110 code more than once per year). These 3 subject search criteria should yield a sufficient number of patient records for statistical analysis.

All patient records will be reviewed and data will be collected and recorded in an electronic Microsoft Excel database file that is saved on an encrypted flash drive. The only patient identifier recorded will be the patient records number. Once data collection is complete, or at a maximum of 3 years from the start of the study, all identifying information will be deleted and only de-identified data saved on a separate electronic file will be analyzed. No code key will be required.

Data will be analyzed using ANOVA (F-test). If multiple variables are used, analysis will be by using generalized estimating equations (GEE).

Inclusion Criteria:

• Active patient of the School of Dental Medicine, University at Buffalo.

• The remaining eligibility criteria varies between the three distinct subject populations, which are noted below. All eligibility criteria is selected for by an electronic search of patient records performed by the IT Department at the School of Dental Medicine, University at Buffalo.

  1. Periodontally healthy patients:

     1. A treatment code of D1110 or D111 was processed at least once but excluding patients that were ever assigned a treatment code of U4990
     2. A 3rd or 4th year pre-doctoral dental student provider
     3. 35 years or older as of 1/1/2016
     4. Patient presented to clinic between 1/1/2016-12/31/2016

  2. Patients with history of advanced periodontal treatment, group 1:

     1. All patients presenting to the Postgraduate Periodontics Department at UB and being seen by a periodontics resident
     2. Time period between 1/1/2000-12/31/2017
     3. Patients will be 35 years or older at time of initial exam
     4. Patients presenting for reasons other than chronic periodontitis treatment (e.g. crown lengthening) will be labeled as such.

  3. Patients with history of advanced periodontal treatment, group 2:

     1. All patients treated in the faculty practice of one periodontist that remained active patients during the time period 1/1/2016-12/31-2016
     2. All patients were 35 years or older at time of initial exam

Duplicates within groups are eliminated.

Exclusion Criteria:

• inadequate data from records

Note: the majority of patient records selected by the search criteria done electronically by the IT department will be included in the study, since the search criteria very closely overlaps the overall study criteria

The study population is sampled from the patient records available at the School of Dental Medicine, University at Buffalo, State University of New York. The patient records reviewed will be of patients seen in the predoctoral as well as postgraduate clinics.

The third group population is sampled from the patient records available from the faculty practice of one provider located at the University of Buffalo, State University of New York