Enamel is the most calcified tissue in the body and is composed of 92-96% by organic substances in particular hydroxyapatite. Hydroxyapatite nanoparticles are similar to the morphology and structure of tooth enamel apatite crystals and has been studied as a biomimetic material for enamel remineralization. Dentin hypersensitivity is a very common disorder in the adult population and it is characterized by short and intensive pain, in response to thermal or chemical stimuli. Dentin hypersensitivity can be generalized or localized, it can simultaneously affect one or more tooth surfaces and depends on the duration of the stimulus applied. In addition, there are numerous factors that can affect this condition, including gum recessions, enamel erosion, dentin exposure and periodontal disease. Many patients suffer from hypersensitivity during professional oral hygiene. The Vector system (Durr Dental, Bietigheim-Bissin gen, Germany) generates ultrasonic vibrations at a frequency of 25 kHz, which are converted by a resonant ring in a horizontal oscillation that is deflected vertically. In particular, the Vector Polish handpiece with a solution of hydroxyapatite is activated through ultrasound and it has the ability to favor the occlusion of the dentinal tubules leading to a reduction in hypersensitivity. The tip of the handpiece moves parallel along the axis of the insert, suitable for use in combination with the polishing fluid containing hydroxyapatite. The presence of this fluid associated with ultrasonic allows the root biofilm to be broken down thanks to cavitation and hydrodynamic forces; furthermore, avoiding horizontal vibrations caused a lower hypersensitivity compared to manual instruments. The aim of this randomized, controlled, split-mouth study is to investigate whether this device is effective in maintaining periodontal patients and is more gentle and comfortable during treatment, specifically in reducing sensitivity.

To test this hypothesis, the mouth of each patients, upon initial evaluation, were divided in 2 parts: before a session of nonsurgical supportive therapy in half mouth the test sites (probing depth > 5 mm or 5 mm with bleeding on probing) are treated with a traditional handpiece (control group) in the other half mouth the test sites are treated with an innovative handpiece which carries hydroxyapatite (test group).

The prevalence of residual pockets will be evaluated at 6 weeks, 3 and 6 months after the initial therapy and compared between the two groups.

TRIAL DESIGN:

A prospective, single-masked, randomized, split-mouth, longitudinal clinical trial.

POPULATION Forty-four (44) adults, aged 18-75 years, will be entered into study (randomized). It is expected that forty (40) subjects will complete the study.

Randomized subjects who deviate from the protocol (major protocol deviation) and, for this reason, are excluded from the analysis, will be replaced to guarantee that the sample required for the analysis (40) is reached.

Inclusion Criteria:

• Signed Informed Consent Form.
• Male and female subjects, aged 18-75 years, inclusive.
• Good general health (free of systemic diseases such as diabetes, HIV infection or genetic disorder, ongoing malignant disease of any type that could influence the outcome of the treatment and might interfere with the evaluation of the study objectives).
• History of periodontitis staging III or IV grading B or C
• At least 4 sites (split mouth 2 - 2) with probing depth ≥6 mm or pockets of 5 mm with bleeding on probing.
• Previous periodontal non-surgical treatment at least 3 months maximum 6 months.
• Availability for the 6-month duration of the study for an assigned subject.

Exclusion Criteria:

• Not willing to follow the agreed protocol.
• Presence of orthodontic appliances.
• Smokers more than 10 cigarettes per day
• Tumors or significant pathology of the soft or hard tissues of the oral cavity.
• Current radiotherapy or chemotherapy.
• Pregnant women.
• Current or past (within 3 months prior to enrollment) assumption of medications that may influence periodontal conditions and/or interfere with healing following