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Trial registered on ANZCTR


Registration number
ACTRN12621000570886
Ethics application status
Approved
Date submitted
3/03/2021
Date registered
17/05/2021
Date last updated
17/05/2021
Date data sharing statement initially provided
17/05/2021
Date results information initially provided
17/05/2021
Type of registration
Retrospectively registered

Titles & IDs
Public title
The relationship between diet, dental caries risk and the glycemic index
Scientific title
The impact of carbohydrate quality on dental plaque pH: does the glycemic index matter for dental health in otherwise healthy young individuals?
Secondary ID [1] 303565 0
None
Universal Trial Number (UTN)
Trial acronym
DenGi
Linked study record

Health condition
Health condition(s) or problem(s) studied:
dental caries 320929 0
high carbohydrate diet 320930 0
Condition category
Condition code
Diet and Nutrition 318737 318737 0 0
Other diet and nutrition disorders
Oral and Gastrointestinal 318738 318738 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Participants are required to consume a higher-carbohydrate (>55% energy as carbohydrate), lower-fat (<20% energy as fat) evening meal, based around pasta, rice, or bread, and then fast for 10-12 hours overnight before each test session. In addition, they are required to refrain from brushing their teeth or performing any oral hygiene regime the night before a test or on the morning of a test session.

Test food: A glucose solution containing either 25 or 50 g of available carbohydrate dissolved in 250 mL water will be studied to investigate the impact of different carbohydrate amounts on acute changes in dental plaque pH. Participants will be asked to complete the glucose solution within 3 minutes. The glucose solution will be tested in duplicate in random order in each participant. Participants will complete 6 test sessions (2 reference food sessions and 4 test food sessions), with consecutive sessions separated by at least 1 day.
In addition, four different starchy carbohydrate foods (canned chickpeas, boiled penne pasta, white bread, and instant mashed potatoes prepared with water) representing a wide range of basic carbohydrate foods with known GI values will be compared with a reference glucose solution. All test foods and the reference solution will be consumed in a portion containing 25 g available carbohydrate. The reference glucose solution will be tested twice by each participant at the start and end of the study. Each food will be consumed on one occasion in random order, with consecutive sessions separated by at least 1 day.
Afterwards, three different types of food pairs will be tested: two microwave white rice, two white breads and two breakfast cereals, along with a reference glucose solution. Within each pair, one food has a lower GI than the other, but both foods have a similar texture, processing method, and food form. Each food pair test portion containes 25 g available carbohydrate, with a similar ratio of starch and sugar within each food pair. A dentist collecting and measuring the plaque samples will be blinded to the differences between the two foods within each pair (eg. GI, brand and nutritional information) until after study completion. All test foods will be freshly prepared according to manufacturers’ instructions without any additional ingredients.
Intervention code [1] 319856 0
Lifestyle
Comparator / control treatment
A glucose solution containing 25g of available carbohydrate dissolved in 250 mL water is the reference.
Control group
Active

Outcomes
Primary outcome [1] 326688 0
The primary outcome is the incremental area above the plaque pH response curve (iAAC) for the timepoints 12, 22 and 62 min after completion of the food calculated by using the trapezoidal rule.

Briefly, upon arrival, a fasted dental plaque sample will be collected by a dentist using a sterile plastic dental probe (SI551ST Periodontal 3-Piece Examination Kit, MDDI, Australia) with a metal tip to collect supragingival plaque from the mesial, distal, buccal, and palatal/lingual surfaces of the teeth. A sufficient amount of dental plaque, approximately 1 mm of the tip of the dental probe, will be sampled at each time point. The dental plaque will be suspended in 25 µL of distilled water in a 2.5 mL tube and vortexed for 20 s. Dental plaque pH will be assessed immediately after collection using a calibrated pH electrode (SevenCompactTM pH/Ion S220, Switzerland), which will be inserted into the plaque and water solution. Before each measurement, the electrode will be rinsed in distilled water, dried, and calibrated to pH 7.0. Dental plaque samples will be collected 2, 12 and 32 min or 12, 22 and 62 after complete consumption of the test beverage. A different quadrant of the oral activity will be randomly selected for each plaque sampling.
Timepoint [1] 326688 0
0, 12, 22 and 62 min after eating has been completed.
Secondary outcome [1] 392369 0
Blood sampling and plasma glucose measurement: Capillary finger-prick blood samples (> 0.5 mL) will be collected from a warmed hand twice in the fasted state (-5 and 0 min) and then at regular intervals during the postprandial period for the following 2 hours (15, 30, 45, 60, 90 and 120 min after eating had commenced). Each sample will be centrifuged at 10,000 x g for 45 s immediately after collection and the plasma layer will be stored at -30oC for subsequent analysis. Plasma glucose concentration will be measured in duplicate using a glucose hexokinase assay (Beckman Coulter Inc.) on an automatic centrifugal spectrophotometric clinical chemistry analyzer (Beckman Coulter AU480®, Beckman Instruments Inc., USA).
Timepoint [1] 392369 0
15, 30, 45, 60, 90 and 120 min after eating has commenced.
Secondary outcome [2] 395427 0
A fasting saliva sample (>1 mL) was collected using a Salivette tube (Sarstedt AG & Co, Germany) from participants in sub-studies 2 and 3 for the assessment of saliva buffering capacity using Ericsson’s method. Stimulated saliva was collected for 5 min, after which the collection tube was centrifuged at 2000 x g for 2 min at 20oC. Saliva was then pipetted into an uncoated tube and stored at -30oC. To measure buffering capacity, 1 mL of thawed saliva was mixed with 3 mL HCl (0.5%) and one drop of 2-Octanol (Sigma-Aldrich 2-Octanol 97%, China) was then added to prevent foaming. The solution was then mixed for 20 min in a suspension mixer (Selby, Australia) after which pH was measured using a calibrated pH electrode (SevenCompactTM pH/Ion S220, Switzerland).
Timepoint [2] 395427 0
after completion of the food.

Eligibility
Key inclusion criteria
Healthy adults, aged 18 – 65 years, non-smoking, without any underlying health conditions or dental disease.
Minimum age
18 Years
Maximum age
65 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Individuals with food allergies, impaired glucose tolerance, those regularly taking prescription medications other than standard oral contraceptives, or individuals with orthodontic appliances were excluded.

Study design
Purpose of the study
Prevention
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
None
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
None
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?


The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
The incremental area above the plaque pH response curve (iAAC) or incremental area below the plasma glucose response curve (iAUC) was calculated using the trapezoidal rule, ignoring any area above the baseline line (plaque pH) or below baseline (plasma glucose). GI values for the test products were determined for each participant by ex-pressing their glucose iAUC response for the test food relative to their glucose iAUC response to the reference food. Standard parametric statistical tests (Analysis of Variance) with Bonferroni adjustment were performed using IBM® SPSS® Statistics software (version 24) to determine whether there were any significant differences amongst the dental plaque pH iAAC responses and the GI values of the test products. ANOVA was used to assess the effect of different foods on plaque pH at the maximum decrease in plaque pH (12 min in sub-study 1 and 22 min sub-studies 2 and 3). Pearson correlation coefficients were calculated to test the association between dental plaque pH parameters and GI. P < 0.05 was considered statistically significant. Data are shown as mean ± standard error of the mean unless otherwise stated.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
3/07/2018
Date of last participant enrolment
Anticipated
Actual
12/12/2019
Date of last data collection
Anticipated
Actual
19/12/2019
Sample size
Target
36
Accrual to date
Final
32
Recruitment in Australia
Recruitment state(s)
NSW
Recruitment hospital [1] 18830 0
Royal Prince Alfred Hospital - Camperdown
Recruitment postcode(s) [1] 33281 0
2006 - The University Of Sydney

Funding & Sponsors
Funding source category [1] 307988 0
University
Name [1] 307988 0
The University of Sydney
Country [1] 307988 0
Australia
Primary sponsor type
University
Name
The University of Sydney
Address
The University of Sydney, Camperdown NSW 2006.
Country
Australia
Secondary sponsor category [1] 308710 0
None
Name [1] 308710 0
Address [1] 308710 0
Country [1] 308710 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 307982 0
Human Research Ethics Committee at the University of Sydney
Ethics committee address [1] 307982 0
The University of Sydney, Camperdown NSW 2006
Ethics committee country [1] 307982 0
Australia
Date submitted for ethics approval [1] 307982 0
11/02/2018
Approval date [1] 307982 0
25/05/2018
Ethics approval number [1] 307982 0
2017/801

Summary
Brief summary
The consumption of sugary carbohydrate foods has been associated with changes in dental plaque pH and an increased risk of dental caries formation. The dental health impact of starchy carbohydrates, in particular, those with a high glycemic index (GI) has not been well examined. This study investigates the effect of different carbohydrate foods, varying in their GI, on acute changes in dental plaque pH. In a series of experiments in healthy adults, common starchy carbohydrate foods, along with an oral glucose solution will be consumed in fixed 25 g available carbohydrate portions. The change in dental plaque pH will be assessed postprandially over 1 hour and capillary plasma glucose concentration will be measured at regular intervals over 2 hours.
Trial website
None
Trial related presentations / publications
None
Public notes
None

Contacts
Principal investigator
Name 109126 0
Prof Joerg Eberhard
Address 109126 0
The Charles Perkins Centre, The University of Sydney, Camperdown NSW 2006
Country 109126 0
Australia
Phone 109126 0
+61 437487452
Fax 109126 0
Email 109126 0
[email protected]
Contact person for public queries
Name 109127 0
Joerg Eberhard
Address 109127 0
The Charles Perkins Centre, The University of Sydney, Camperdown NSW 2006
Country 109127 0
Australia
Phone 109127 0
+61 437487452
Fax 109127 0
Email 109127 0
[email protected]
Contact person for scientific queries
Name 109128 0
Joerg Eberhard
Address 109128 0
The Charles Perkins Centre, The University of Sydney, Camperdown NSW 2006
Country 109128 0
Australia
Phone 109128 0
+61 437487452
Fax 109128 0
Email 109128 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
Dental plaque pH values, glycemic index for the tested foods.
When will data be available (start and end dates)?
No end date, available for 5 years after publication
Available to whom?
Research.
Available for what types of analyses?
Secondary analysis.
How or where can data be obtained?
Please email the PI at [email protected]


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.