Condition category
Oral Health
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status
Results overdue

Plain English Summary

Background and study aims
Dental caries, or cavities, are one of the most common long-term health conditions worldwide. They are thought to be caused by a buildup of bacteria on the tooth surface (biofilm), which produces substances that lead to tooth decay. It is still a challenge for dentists to assess current caries in a patient, as it is only after a few months that the damage to the tooth becomes visible. There is evidence to suggest that it is not the presence of bacteria alone that leads to caries but the type of bacteria present. The aim of this study is to compare the composition of biofilms (bacteria) living in the mouths of people suffering from caries and those who are not.

Who can participate?
Healthy adults with three or more caries in need of treatment and healthy adults without caries who have had no new fillings in the last two years.

What does the study involve?
For eight hours, participants are asked to wear a mouth piece made from cattle teeth on their upper jaw so that a biofilm can form undisturbed. Samples of saliva in the mouth are taken after two, four and eight hours. These are then tested in the laboratory in order to assess the bacteria living in the both, which is then compared between the participants with caries and those without.

What are the possible benefits and risks of participating?
There are no direct benefits or risks involved with participating.

Where is the study run from?
1. Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Saarland University Medical Center (Germany)
2. Policlinic of Operative and Pediatric Dentistry, Carl Gustav Carus TU Dresden (Germany)

When is the study starting and how long is it expected to run for?
July 2009 to September 2016

Who is funding the study?
Deutsche Forschungsgemeinschaft (Germany)

Who is the main contact?
Professor Stefan Rupf

Trial website

Contact information



Primary contact

Prof Stefan Rupf


Contact details

Clinic of Operative Dentistry
Periodontology and Preventive Dentistry
Saarland University
+49 68411624962

Additional identifiers

EudraCT number number

Protocol/serial number

HA 5192/7-1, HA 2718/11-1, RU 866/2-1

Study information

Scientific title

Comparison of initial oral microbiomes of caries actives and caries inactives using a dynamic in situ biofilm model in young adults


Study hypothesis

The aim of this study is to compare the microbial composition in caries active and caries inactive adults for 2, 4 and 8 hours in in situ biofilms and saliva.

Ethics approval

1. Ethics Committies of the Saarland University, 03/09/2009, ref: Sn52/05/2009
2. Dresden University, 19/10/2012, ref: EK275092012

Study design

Observational case-control study

Primary study design


Secondary study design

Case-control study

Trial setting


Trial type


Patient information sheet

Only available in German and not available in web format, please use the contact details below to request a patient information sheet


Dental caries


Twenty-seven volunteers are enrolled in the study, 14 caries active individuals with at least three active dentin caries lesions and 13 caries inactive individuals.

Polished bovine enamel slabs mounted in buccal direction on acrylic splints are worn by all volunteers in their upper jaws for in situ biofilm formation for eight hours and 1 ml of unstimulated saliva is collected after two, four and eight hours from each individual. Amplicon sequencing of the V1 and V2 variable regions of the 16S rRNA gene is performed on saliva samples using MiSeq. Differentially abundant operational taxonomic units (OTUs) are identified using the Wilcoxon-Mann-Whitney test. Random forests are used for sample classification and evaluated by cross-validation.

Intervention type



Drug names

Primary outcome measure

Differences in the biofilms are assessed by amplicon sequencing of the V1 and V2 variable regions of the 16S rRNA gene using MiSeq on samples collected at 2, 4 and 8 hours.

Secondary outcome measures

No secondary outcome measures

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Test group caries active:
1. Aged between 18 and 45
2. Minimum 24 teeth
3. Written informed consent
4. Recruitment in the outpatient departments of Saarland and Dresden Universities
5. Sufficient oral hygiene (plaque index < 50%, bleeding index < 15%)
6. Three or more active caries lesions (need of invasive treatment)

Control group caries inactive:
1. Aged between 18 and 45
2. Minimum 24 teeth
3. Written informed consent
4. Recruitment in the outpatient departments of Saarland and Dresden Universities
5. Sufficient oral hygiene (plaque index < 50%, bleeding index < 15%)
6. No active caries lesions, no new fillings within the last 2 years

Participant type

Healthy volunteer

Age group




Target number of participants


Participant exclusion criteria

1. Smokers
2. Pregnancy
3. Drug use
4. Periodontal disease
5. Other oral diseases except caries
6. Other diseases and conditions

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Saarland University Medical Center
Clinic of Operative Dentistry, Periodontology and Preventive Dentistry Building 73

Trial participating centre

Policlinic of Operative and Pediatric Dentistry
Carl Gustav Carus TU Dresden Fetscherstraße 74

Sponsor information


Deutsche Forschungsgemeinschaft

Sponsor details

Kennedyallee 40

Sponsor type

Research organisation



Funder type

Research organisation

Funder name

Deutsche Forschungsgemeinschaft

Alternative name(s)

German Research Association, DFG

Funding Body Type

private sector organisation

Funding Body Subtype

Trusts, charities, foundations (both public and private)



Results and Publications

Publication and dissemination plan

Planned publication in a high-impact peer reviewed journal.

IPD Sharing plan:
The datasets generated during and/or analysed during the current study are/will be available upon request from Professor Stefan Rupf (

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes