Adult patients diagnosed with Alzheimer's disease

The control group will consist of patients who attend consultations at the Faculty of Dentistry of the University of Lisbon, matched for age, gender and other confounding factors, such as smoking and systemic diseases (diabetes).

All participants, in the test group and in the control group, will undergo an initial periodontal evaluation. The clinical evaluation will always be carried out by the same examiner, the author of the study, in order to guarantee calibrated observations. During data collection, intra-observer calibration will be performed, as recommended by the WHO (WHO, 1993), in order to minimize diagnostic variability and verify agreement

The probing depth corresponds to the distance from the gingival margin to the bottom of the sulcus or periodontal pocket. Probing depth measurement will be performed at six locations per tooth, three locations per buccal and three locations per lingual/palatal

The clinical insertion level corresponds to the distance from an enamel-cementary junction (JAC) to the bottom of the pocket.

• In cases where there is gingival recession, the insertion level is complete through the sum of the probing depth value and the gingival recession value (distance from the gingival margin to the JAC).
• In cases where the gingival margin coincides with the JAC, the insertion level value is the same as the probing depth.
• If there is a pseudo-pocket, characterized by an increase in gingival volume in the coronal direction, the insertion level value will be the result of subtracting the probing depth value and the distance from the gingival margin to the JAC.

For the evaluation of the plaque index (PI), the PI developed by the authors Ainamo and Bay, in 1975, will be used. It is a dichotomous index, which assesses the presence or absence of bacterial plaque in the cervical area of the tooth in four locations, three locations by vestibular and one location by palatine

Bleeding on probing is assessed by looking at bleeding points after periodontal probing. It will be evaluated in six locations per tooth, three locations per buccal and three locations per lingual/palatal. A red circle is placed around the sounding depth value (Lang 1986 and 1990).

Gingival recession will be evaluated in millimeters and is obtained by the distance from the gingival margin to the JAC. It will be evaluated in six locations per tooth, three locations per buccal and three locations per lingual/palatal

Microbiological analysis will be performed using a sample of subgingival bacterial plaque. The sample will be collected at the tooth and at the location with the highest probing depth values in each quadrant.

A sterilized paper tip from the microbiological kit will be introduced to the bottom of the bag, with the aid of tweezers, remaining in the same position for 10 seconds. After collecting the sample, the paper tip will be placed in an individual transfer tube, properly identified. Afterwards, the sample will be sent to the laboratory, where a polymerase chain reaction (PCR) test is performed to identify the following bacteria - A. actinomycetemcomitans, T. forsythia, T. denticola, P. gingivalis, P. intermedia and F. nucleatum.

Cognitive assessment will be performed by neurologists from the Portuguese Alzheimer's Association.

Periodontal diagnosis will be performed, through clinical evaluation, to patients with and without Alzheimer's Disease. The Classification of Periodontal and Peri-implant Diseases and Conditions proposed by the American Association of Periodontology (AAP) and the European Federation of Periodontology (EFP) will be used to determine the prevalence of periodontal disease.

To assess whether adult patients with different stages of Alzheimer's disease have different stages of severity of Periodontitis (I, II, III and IV), in addition to a periodontal evaluation, it is also evaluated through cognitive tests, at which stage of the disease Alzheimer's patient is found.