Plain English Summary
Background and study aims
Neutrophils are the most common type of white blood cell found in the body. They enter the mouth mostly through the small open space of the gums, surrounding the teeth. These are also known as gingival crevices. Little is known about these oral neutrophils functional potential (what they can do) and their possible contribution in the maintenance of oral health. This study aims to investigate the presence and functional capabilities of oral neutrophils in people with no teeth (edentulous) since these individuals lack the presence of the gingival crevices found in people that still have their teeth.
What does the study involve?
This study looks at neutrophils taken from people without teeth but with a healthy mouth (orally healthy) with orally healthy people with teeth (dentate). Rinse and blood samples are taken from each person and analysed for functional activity (that is, ti see what functions the neutrophils have in the mouth) on the same day. All participants are informed about the purpose of the study, are given written information and are asked for their written consent prior to the start of the study.
What are the possible benefits and risks of participating?
This observational study gives new insights in the functioning of the immune response within the mouth of people without teeth. No risks or symptoms are to be expected to occur due to participating in this study.
Where is the study run from?
Academic Centre for Dentistry Amsterdam (Netherlands)
When is the study starting and how long is it expected to run for?
May 2014 to January 2016
Who is funding the study?
University of Amsterdam (Netherlands)
Who is the main contact?
Dr Elena Nicu
Impaired polymorphonuclear neutrophils in the oral cavity of edentulous subjects
Edentulous subjects present with less functional polymorphonuclear neutrophils compared to dentate subjects.
Observational case-control study
Primary study design
Secondary study design
Patient information sheet
Edentulous subjects wearing full dentures for a minimum period of 1 year.
Volunteers were recruited at the Academic Centre for Dentistry Amsterdam (ACTA) in the Netherlands. Subjects were either patients at the dental clinics or non-professional personnel. All subjects were screened for their periodontal condition and additionally dental radiographs were taken in order to confirm the absence of alveolar bone loss. Edentulous subjects were included if they have been wearing a full denture for a minimum period of 1 year.
All subjects were informed about the purpose of the study, received written information and had given written consent prior to the start of this study. Each subject was asked to donate one blood sample and 4x oral rinse samples. Samples were donated on the same day. Venous blood samples were drawn from the antecubital fossa into one 9 ml sodium heparin blood collection tube. Oral rinse samples were taken before any other intra-oral procedures were carried out in order to avoid contamination. The edentulous subjects were asked to remove their dentures before the supervised sample collection. All subjects were instructed not to gargle nor clear their throat during the sampling procedure. Four serial rinses of the oral cavity were obtained with 10 ml of sterile sodium chloride solution (0.9%) for 30 seconds, each with 4.5 min intermission. The rinse samples were pooled into one collection tube.
Neutrophil counts were determined in blood and from oral rinses. Additionally cell functionality was determined using flow cytometry (cell membrane integrity, cell activation status and reactive oxygen species).
Primary outcome measure
The presence of functionally impaired neutrophils in the oral cavity of edentulous subjects, measured using flow cytometry directly after sampling. All samples were analyzed using flow cytometry on the same day.
Secondary outcome measures
1. Cell number count, using a Muse cell counting device.
2. Cell membrane integrity, analysed using propidium iodide staining.
3. Neutrophil expression of cell activation markers CD11b, CD63 and CD66b and corrected for non-specific binding of isotype control antibodies.
4. Presence of constitutive reactive oxygen species (ROS) production, detected using dihydrorhodamine 123.
5. Presence of ROS production in response to stimulation, determined in samples incubated with forbid myristate acetate (PMA) or Fusobacterium nucleatum
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
edentulous for a minimum period of 1 year wearing a full denture OR dentate subjects with a minimum of 20 teeth.
Target number of participants
Participant exclusion criteria
conditions that are known to systemically affect the neutrophil functionality (such as Diabetes, hematological disorders, recent illness, allergies). Furthermore, antbiotics use, pregnancy, removal partial dentures, night guards, orthodontic banding, oral piercings, oral lesions were excluded.
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Academic Centre for Dentistry Amsterdam (ACTA)
Gustav Mahlerlaan 3004
Universiteit van Amsterdam
University of Amsterdam, UvA
Funding Body Type
private sector organisation
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Intention to publish date
Participant level data
Available on request
Basic results (scientific)