Fluoride Retention in the Mouth of Older Adults

Individuals with dry mouth (a reduction in the production of saliva) suffer from high rates of oral diseases. Dry mouth is a common problem among older individuals, because many medications to control chronic conditions (such as blood pressure, bladder-control problems and depression) reduce the flow of saliva. For these individuals, fluoride is used to maintain a good oral health. Usually, higher fluoride concentration products, such as prescription toothpastes, are recommended. In this project, the ability to increase fluoride retention in the mouth by using calcium before a conventional fluoride rinse will be tested in older adults with a range of salivary flow rates. This approach was never tested in patients with dry mouth, for whom the treatment with calcium may also be beneficial. A crossover, clinical study with two experimental phases will be conducted, in which patients with a range of saliva flows (from normal to dry mouth) will rinse with a fluoride rinse only (used at over the counter concentration), or a fluoride rinse preceded by a calcium rinse. The concentration of fluoride and calcium in the saliva and dental plaque residues will be determined up to two hours after the rinse(s), to test the effect of the approach to optimize fluoride retention in the mouth of patients with dry mouth.

Participants with normal to dry mouth will first test a Fluoride mouthwash containing 226 ppm of fluoride, and fluoride concentration in saliva and dental biofilm will be assessed overtime for up to 2 hours. After a washout period of at least 3 days, they will then test a Calcium mouthwash (150 milimolars of calcium) immediately before the Fluoride mouthwash, and fluoride concentration in saliva and dental biofilm will be assessed overtime for up to 2 hours.

Participants with normal to dry mouth will first test a Calcium mouthwash (150 milimolars of calcium) immediately before a Fluoride mouthwash containing 226 ppm of fluoride, and fluoride concentration in saliva and dental biofilm will be assessed overtime for up to 2 hours. After a washout period of at least 3 days, they will then test the Fluoride mouthwash alone, and fluoride concentration in saliva and dental biofilm will be assessed overtime for up to 2 hours.

Sodium fluoride, at a concentration of 0.05% (226 parts per million (ppm) of fluoride), will be used to rinse the mouth for 1 minute and expectorated.

Calcium lactate, at a concentration of 150 milimolar, will be used to rinse the mouth for 1 minute and expectorated; immediately after, a sodium fluoride rinse, at a concentration of 0.05% (226 ppm of fluoride), will be used to rinse the mouth for 1 minute, and expectorated.

Dental biofilm was collected at baseline (before mouthwash(es)), and the fluid phase was separated using centrifugation. Fluoride concentration in the dental biofilm fluid was measured using an ion-specific electrode adapted for microanalysis.

Dental biofilm was collected 15 minutes after mouthwash(es), and the fluid phase was separated using centrifugation. Fluoride concentration in the dental biofilm fluid was measured using an ion-specific electrode adapted for microanalysis.

Dental biofilm was collected 60 minutes after mouthwash(es), and the fluid phase was separated using centrifugation. Fluoride concentration in the dental biofilm fluid was measured using an ion-specific electrode adapted for microanalysis.

Dental biofilm was collected 120 minutes after mouthwash(es), and the fluid phase was separated using centrifugation. Fluoride concentration in the dental biofilm fluid was measured using an ion-specific electrode adapted for microanalysis.

Dental biofilm was collected at baseline (before mouthwash(es)). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of fluoride reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Fluoride concentration in the dental biofilm solids acid extract was measured using an ion-specific electrode adapted for microanalysis; protein concentration in the alkali extract was determined using the Lowry colorimetric method. Fluoride concentration in the biofilm was expressed as micrograms of fluoride/milligrams of protein.

Dental biofilm was collected 15 minutes after mouthwash(es). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of fluoride reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Fluoride concentration in the dental biofilm solids acid extract was measured using an ion-specific electrode adapted for microanalysis; protein concentration in the alkali extract was determined using the Lowry colorimetric method. Fluoride concentration in the biofilm was expressed as micrograms of fluoride/milligrams of protein.

Dental biofilm will be collected 60 minutes after mouthwash(es). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of fluoride reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Fluoride concentration in the dental biofilm solids acid extract was measured using an ion-specific electrode adapted for microanalysis; protein concentration in the alkali extract was determined using the Lowry colorimetric method. Fluoride concentration in the biofilm was expressed as micrograms of fluoride/milligrams of protein.

Dental biofilm was collected 120 minutes after mouthwash(es). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of fluoride reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Fluoride concentration in the dental biofilm solids acid extract was measured using an ion-specific electrode adapted for microanalysis; protein concentration in the alkali extract was determined using the Lowry colorimetric method. Fluoride concentration in the biofilm was expressed as micrograms of fluoride/milligrams of protein.

Fluoride concentration in dental biofilm fluid collected at baseline (before mouthwash(es)), 15, 60 and 120 minutes after mouthwash(es) was expressed as the area under the curve of fluoride concentration in dental biofilm fluid as a function of time (parts per million x min).

Fluoride concentration in dental biofilm solids collected at baseline (before mouthwash(es)), 15, 60 and 120 minutes after mouthwash(es) was expressed as the area under the curve of fluoride concentration in dental biofilm solids as a function of time (micrograms of fluoride x minutes/ milligram of proteins).

Unstimulated saliva was collected at baseline (before mouthwash(es)), for 5 minutes. Fluoride concentration in unstimulated saliva was measured using an ion-specific electrode adapted for microanalysis.

Unstimulated saliva was collected 16 minutes after mouthwash(es), for 5 minutes. Fluoride concentration in unstimulated saliva was measured using an ion-specific electrode adapted for microanalysis.

Unstimulated saliva was collected 30 minutes after mouthwash(es), for 5 minutes. Fluoride concentration in unstimulated saliva was measured using an ion-specific electrode adapted for microanalysis.

Unstimulated saliva was collected 61 minutes after mouthwash(es), for 5 minutes. Fluoride concentration in unstimulated saliva was measured using an ion-specific electrode adapted for microanalysis.

Unstimulated saliva was collected 90 minutes after mouthwash(es), for 5 minutes. Fluoride concentration in unstimulated saliva was measured using an ion-specific electrode adapted for microanalysis.

Unstimulated saliva was collected 121 minutes after mouthwash(es), for 5 minutes. Fluoride concentration in unstimulated saliva was measured using an ion-specific electrode adapted for microanalysis.

Dental biofilm will be collected at baseline (before mouthwash(es)), and the fluid phase will be separated using centrifugation. Calcium concentration in the dental biofilm fluid will be measured using an ion-specific electrode adapted for microanalysis, and will be expressed in millimolar.

Dental biofilm will be collected 15 minutes after mouthwash(es), and the fluid phase will be separated using centrifugation. Calcium concentration in the dental biofilm fluid will be measured using an ion-specific electrode adapted for microanalysis, and will be expressed in millimolar.

Dental biofilm will be collected 60 minutes after mouthwash(es), and the fluid phase will be separated using centrifugation. Calcium concentration in the dental biofilm fluid will be measured using an ion-specific electrode adapted for microanalysis, and will be expressed in millimolar.

Dental biofilm will be collected 120 minutes after mouthwash(es), and the fluid phase will be separated using centrifugation. Calcium concentration in the dental biofilm fluid will be measured using an ion-specific electrode adapted for microanalysis, and will be expressed in millimolar.

Dental biofilm was collected at baseline (before mouthwash(es)). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of calcium reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Calcium concentration in the dental biofilm solids acid extract was measured using a colorimetric reaction (Arsenazo III); protein concentration in the alkali extract was determined using the Lowry colorimetric method. Calcium concentration in the biofilm was expressed as micrograms of calcium/milligrams of protein.

Dental biofilm was collected 15 minutes after mouthwash(es). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of calcium reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Calcium concentration in the dental biofilm solids acid extract was measured using a colorimetric reaction (Arsenazo III); protein concentration in the alkali extract was determined using the Lowry colorimetric method. Calcium concentration in the biofilm was expressed as micrograms of calcium/milligrams of protein.

Dental biofilm was collected 60 minutes after mouthwash(es). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of calcium reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Calcium concentration in the dental biofilm solids acid extract was measured using a colorimetric reaction (Arsenazo III); protein concentration in the alkali extract was determined using the Lowry colorimetric method. Calcium concentration in the biofilm was expressed as micrograms of calcium/milligrams of protein.

Dental biofilm was collected 120 minutes after mouthwash(es). The fluid phase of the biofilm was collected after centrifugation, and the remaining solids were treated with strong acid for dissolution of calcium reservoirs. Solids remaining after acid extraction were treated with strong alkali for total dissolution of the biofilm and estimation of biofilm mass by protein concentration. Calcium concentration in the dental biofilm solids acid extract was measured using a colorimetric reaction (Arsenazo III); protein concentration in the alkali extract was determined using the Lowry colorimetric method. Calcium concentration in the biofilm was expressed as micrograms of calcium/milligrams of protein.

Unstimulated saliva was collected at baseline (before mouthwash(es)), for 5 minutes. Calcium concentration in unstimulated saliva was measured using a colorimetric reaction (Arsenazo III).

Unstimulated saliva was collected at 16 minutes after mouthwash(es), for 5 minutes. Calcium concentration in unstimulated saliva was measured using a colorimetric reaction (Arsenazo III).

Unstimulated saliva was collected at 30 minutes after mouthwash(es), for 5 minutes. Calcium concentration in unstimulated saliva was measured using a colorimetric reaction (Arsenazo III).

Unstimulated saliva was collected at 61 minutes after mouthwash(es), for 5 minutes. Calcium concentration in unstimulated saliva was measured using a colorimetric reaction (Arsenazo III).

Unstimulated saliva was collected at 90 minutes after mouthwash(es), for 5 minutes. Calcium concentration in unstimulated saliva was measured using a colorimetric reaction (Arsenazo III).

Unstimulated saliva was collected at 121 minutes after mouthwash(es), for 5 minutes. Calcium concentration in unstimulated saliva was measured using a colorimetric reaction (Arsenazo III).

Fluoride concentration in unstimulated saliva collected at baseline (before mouthwash(es)), 16, 30, 61, 90 and 121 minutes after mouthwash(es) was expressed as the area under the curve of fluoride concentration in saliva as a function of time.

Calcium concentration in dental biofilm fluid collected at baseline (before mouthwash(es)), 15, 60 and 120 minutes after mouthwash(es) will be expressed as the area under the curve of calcium concentration in dental biofilm fluid as a function of time (millimolar x min).

Calcium concentration in dental biofilm solids collected at baseline (before mouthwash(es)), 15, 60 and 120 minutes after mouthwash(es) was expressed as the area under the curve of calcium concentration in dental biofilm solids as a function of time.

Calcium concentration in unstimulated saliva collected at baseline (before mouthwash(es)), 16, 30, 61, 90 and 121 minutes after mouthwash(es) was expressed as the area under the curve of calcium concentration in saliva as a function of time (millimolar x min).

Inclusion Criteria: Provision of signed and dated informed consent form Stated willingness to comply with all study procedures and availability for the duration of the study Good general health as evidenced by medical history Good oral health as evidenced by a clinical oral exam Having at least 20 teeth in the mouth, being at least 4 (natural or crowned) teeth in all four quadrants of the mouth Having salivary flow rate ranging from normal to hyposalivation according to direct flow rate determination methods Agreement to adhere to the study protocol Exclusion Criteria: Unable to understand and/or follow study instructions Active periodontitis Oral pain In need of urgent dental care