Efficacy of Three Toothpastes Using an in Situ Caries Model

Study Overview
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Brief Summary
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This will be a single-centre, randomized, blinded, placebo-controlled, 6-treatment, 4-period crossover, incomplete block design, in situ caries study in healthy adults who wear a removable bilateral mandibular partial denture. The denture will be modified to accommodate 4 gauze-covered specimens of human dental enamel (4x3mm) that have been previously demineralized in vitro to form either S or low-R lesions (2 specimens of each lesion type will be used with each participant). After 14 days of twice daily product use off-site, the 2 S lesion specimens will be removed at the study site, with the remaining 2 low-R lesion specimens removed at the study site after a further 14 days of product use. To determine the remineralization ability of the treatments, all specimens will be analyzed by transverse microradiography (TMR) and enamel fluoride uptake (EFU), with the S lesions additionally analyzed by surface micro hardness (SMH) and the low-R lesions additionally analyzed by quantitative light fluorescence (QLF).

Official Title
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Clinical Efficacy of Three Experimental Toothpastes Using an in Situ Caries Model

Conditions
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Dental Caries

Intervention / Treatment
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* Drug: 0.425 % w/w phytate,1150ppm F
* Drug: 0.85 % w/w phytate,1150ppm F
* Drug: 0.85 % w/w phytate,0.3%ZnCl2 0.5% sodium citrate, 1150ppm F
* Other: 0 ppm F
* Drug: 1150ppm F
* Drug: 0.3%ZnCl2, 0.5% sodium citrate, 1150ppm F


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Demonstrates understanding of the study. Aged 18 to 85 years. Understands and is willing, able and likely to comply with all study procedures and restrictions. Has good general health (in the opinion of the investigator or medically qualified designee). A salivary flow-rate in the range of normal values (unstimulated whole saliva flow- Rate ≥ 0.2 g/minute (min); gum base stimulated whole saliva flow-Rate ≥ 0.8 g/min). Currently wearing a removable mandibular partial denture with sufficient room in the posterior buccal flange area to accommodate two enamel specimens. Have no current active caries or periodontal disease and all restorations in a good state of repair. Willing and capable of brushing their natural teeth with the lower partial denture in place. Exclusion Criteria: Pregnant or breast feeding women. Known or suspected intolerance or hypersensitivity to the study materials or their stated ingredients. Currently taking antibiotics or have taken antibiotics in the two weeks prior to the screening visit. Unable to measure product weights accurately using the assigned study scale as determined by the study staff as demonstrated. Participation in another clinical study or receipt of an investigational drug within 30 days of the screening visit. Have received a professional fluoride treatment within 14 days of randomization to the first treatment. Recent history (within the last year) of alcohol or other substance abuse.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental Dentifrice1<br>Participants will brush their natural teeth with a pre-wetted toothbrush and their assigned dentifrice for one timed minute, ensuring the enamel specimens retained within their mouths are not directly brushed. Participants should then rinse their mouths with 15ml of tap water for approximately 10s. | Drug: 0.425 % w/w phytate,1150ppm F<br>* Participants were assigned with 1.5±0.1g twice daily dentifrice for one timed minute.<br>|
| Experimental: Experimental Dentifrice 2<br>Participants will brush their natural teeth with a pre-wetted toothbrush and their assigned dentifrice for one timed minute, ensuring the enamel specimens retained within their mouths are not directly brushed. Participants should then rinse their mouths with 15ml of tap water for approximately 10s. | Drug: 0.85 % w/w phytate,1150ppm F<br>* Participants were assigned with 1.5±0.1g twice daily dentifrice for one timed minute.<br>|
| Experimental: Experimental Dentifrice 3<br>Participants will brush their natural teeth with a pre-wetted toothbrush and their assigned dentifrice for one timed minute, ensuring the enamel specimens retained within their mouths are not directly brushed. Participants should then rinse their mouths with 15ml of tap water for approximately 10s. | Drug: 0.85 % w/w phytate,0.3%ZnCl2 0.5% sodium citrate, 1150ppm F<br>* Participants were assigned with 1.5±0.1g twice daily dentifrice for one timed minute.<br>|
| Placebo Comparator: Reference Product 1<br>Participants will brush their natural teeth with a pre-wetted toothbrush and their assigned dentifrice for one timed minute, ensuring the enamel specimens retained within their mouths are not directly brushed. Participants should then rinse their mouths with 15ml of tap water for approximately 10s. | Other: 0 ppm F<br>* Participants were assigned with 1.5±0.1g twice daily dentifrice for one timed minute.<br>|
| Active Comparator: Reference Product 2<br>Participants will brush their natural teeth with a pre-wetted toothbrush and their assigned dentifrice for one timed minute, ensuring the enamel specimens retained within their mouths are not directly brushed. Participants should then rinse their mouths with 15ml of tap water for approximately 10s. | Drug: 1150ppm F<br>* Participants were assigned with 1.5±0.1g twice daily dentifrice for one timed minute.<br>|
| Active Comparator: Reference Product 3<br>Participants will brush their natural teeth with a pre-wetted toothbrush and their assigned dentifrice for one timed minute, ensuring the enamel specimens retained within their mouths are not directly brushed. Participants should then rinse their mouths with 15ml of tap water for approximately 10s. | Drug: 0.3%ZnCl2, 0.5% sodium citrate, 1150ppm F<br>* Participants were assigned with 1.5±0.1g twice daily dentifrice for one timed minute.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage Surface Microhardness Recovery (SMHR) of Phyte (0% 0.425% and 0.85%) at 2 Weeks | SMHR test was used to assess the changes in mineralization status of partially demineralized enamel specimens using a Wilson 2100 Hardness tester. SMH was determined by measuring the length of the indentations of enamel specimens. % SMHR was calculated from indentation length (micrometer [μm]) of sound enamel specimen at baseline (B), indentation length (μm) after in vitro demineralization(D), indentation length (μm) after intra-oral exposure (R): [D-R/D-B]*100. | Baseline upto 2 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| % SMHR of 0.85% Phytate Compared to 0% Phytate, in Presence of 1150ppm Fluoride and 0.3% ZnCl2, 0.3% ZnCl2 Compared to 0% ZnCl2 in the Presence of 1150ppm Fluoride and 0.3% ZnCl2 Compared to 0% ZnCl2 in the Presence of 1150ppm Fluoride and 0.85% Phytate | SMHR test was used to assess the changes in mineralization status of partially demineralized enamel specimens using a Wilson 2100 Hardness tester. SMH was determined by measuring the length of the indentations of enamel specimens. % SMHR was calculated from indentation length (μm) of sound enamel specimen at baseline (B), indentation length (μm) after in vitro demineralization(D), indentation length (μm) after intra-oral exposure (R): [D-R/D-B]*100. | Baseline upto 2 weeks | 
| Transverse Microradiography (TMR) Net Remineralization Change (ΔM) Value of Phytate (0% 0.452% and 0.85%) at 4 Weeks | TMR was used to assess changes in the mineral status of partially demineralized enamel specimens. Lesions were analyzed at baseline and Integrated Mineral Loss (∆Z): (∆Z =(lesion depth x 87) - area under the curve [Area under the curve which relates volume % mineral at distances from the specimen surface with respect to section thickness]). After treatment a further section was taken from each lesion specimen for radiography assessment; ∆Z was calculated. The change which occurred in mineral content (∆M) of the lesions as a result of treatment was calculated by: ∆M= (baseline ∆Z - Post-treatment ∆Z). | Baseline upto 4 weeks | 
| TMR Δm Value of 0.85% Phytate Compared to 0% Phytate, in the Presence of 1150ppm F and 0.3% ZnCl2, 0.3% ZnCl2 Compared to 0% ZnCl2 in the Presence of 1150ppm F and 0.3% ZnCl2 Compared to 0% ZnCl2 in the Presence of 1150ppm F and 0.85% Phytate | TMR was used to assess changes in the mineral status of partially demineralized enamel specimens. Lesions were analyzed at baseline and Integrated Mineral Loss (∆Z): (∆Z =(lesion depth x 87) - area under the curve [Area under the curve which relates volume % mineral at distances from the specimen surface with respect to section thickness]). After treatment a further section was taken from each lesion specimen for radiography assessment; ∆Z was calculated. The change which occurred in mineral content (∆M) of the lesions as a result of treatment was calculated by: ∆M= (baseline ∆Z - Post-treatment ∆Z). | Baseline upto 4 weeks | 
| Enamel Fluoride Uptake (EFU) of All Study Formulation Variables | The microdrill enamel biopsy technique was used to analyze the fluoride uptake by enamel. Each enamel specimen was mounted on the long axis of a drill attached to a microdrill and drilled to a depth of approximately 100 μm through the entire lesion (four cores per specimen). The enamel powder pooled from four drilling samples was then immediately analyzed for fluoride content using fluoride specific electrode and pH/ion meter. The amount of fluoride-uptake by enamel was calculated based on the amount of fluoride divided by the area of the enamel cores and expressed as μg/cm^2. | At Week 2 | 
| Enamel Fluoride Uptake (EFU) of All Study Formulation Variables | The microdrill enamel biopsy technique was used to analyze the fluoride uptake by enamel. Each enamel specimen was mounted on the long axis of a drill attached to a microdrill and drilled to a depth of approximately 100 μm through the entire lesion (four cores per specimen). The enamel powder pooled from four drilling samples was then immediately analyzed for fluoride content using fluoride specific electrode and pH/ion meter. The amount of fluoride-uptake by enamel was calculated based on the amount of fluoride divided by the area of the enamel cores and expressed as μg/cm^2. | At Week 4 |