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

Plain English Summary

Background and study aims
There are many studies in the last few decades that established a connection of plaque-induced periodontitis with other systemic diseases. The connection between periodontitis and chronic kidney disease is also studied. Chronic kidney disease is a progressive illness characterized by nephron destruction. Primary causes for that destruction are diabetes, pyelonephritis, glomerulonephritis, nephrosclerosis, polycystic kidney disease and collagen vascular diseases. The loss of kidney function leads to an accumulation of harmful metabolic products that can affect various organs. Clinical progress that leads to kidney failure can be divided into three progressive stages: first decreased kidney reserve, then decreased kidney function and at the end kidney failure or uremia. The last stage is treated either by dialysis or kidney transplantation. There are two types of dialysis: hemodialysis and peritoneal dialysis. Hemodialysis is a procedure in which nitrogen and other toxic metabolic waste products are removed from the blood by the hemodialysis system. The change between the patient's blood plasma and dialysate is made through a semipermeable membrane that allow uremic toxins to flow from the blood plasma. In peritoneal dialysis, dialysis fluid (called dialysate) is infused into the peritoneal cavity through the patient's catheter. The fluid (approximately 1-2- litres) is held (dwells) within the abdomen for a prescribed period of time. Hemodialysis is usually conducted three times a week for 3-4 hours and peritoneal dialysis is conducted at home or another clean environment each day. Peritoneal dialysis is cheaper and according to some research, it has a higher survival rate in the first two to four years. There is evidence that the quality of life is also better with peritoneal dialysis. But the percentage of patients on hemodiyalysis is higher.
Aim of the study: to compare periodontal status between patients on hemodialysis and peritoneal dialysis, analyze main laboratory parameters in relation to periodontal indices and by means of questionnaire determine oral hygienic habits, smoking habits and alcohol consumption in relation to dialysis type and periodontal status and to establish the need for periodontal therapy.

Who can participate?
Patients aged 18 and over on dialysis (peritoneal or hemodialysis).

What does the study involve?
Patients that attend Clinic of Internal Medicine, University Hospital Center “Sestre milosrdnice”, Zagreb, Croatia and are on dialysis therapy (peritoneal or hemodialysis) are examined. All involved patients sign informed consent. The examination consists of taking periodontal indices: approximal plaque index, periodontal probing depth, periodontal bleeding index, bleeding on probing, gingival recession, clinical attachment level and calculation of periodontally inflamed surface area. All indices are measured at six sites on each tooth using a periodontal probe (PCP 15; Hu-Friedy, Chicago, IL, USA).

What are the possible benefits and risks of participating?
Benefits for the patients are free periodontal examination and free periodontal treatment if needed. The potential benefit is also decreased systemic inflammatory response and decreased mortality. There are no known risks.
Where is the study run from? Clinic of Internal Medicine, University Hospital Center “Sestre milosrdnice”, Zagreb, Croatia.
When is the study starting and how long is it expected to run for? February 2015-January 2016

Who is funding the study?
Funded by the main researcher.

Who is the main contact?
Bojana Križan Smojver

Trial website

Contact information



Primary contact

Dr Bojana Križan Smojver


Contact details

Department of Endodontics with Restorative Dentistry
Oral Medicine and Periodontology
Dental Clinic Zagreb
Ulica Ivana Perkovca 3



Additional contact

Prof Andrej Aurer


Contact details

Department of Periodontology
School of Dentistry
University of Zagreb
Gundulićeva 5



Additional contact

Dr Karmela Altabas


Contact details

Clinic of Internal Medicine
University Hospital Center “Sestre milosrdnice"

Additional identifiers

EudraCT number

Nil known number

Nil known

Protocol/serial number


Study information

Scientific title

Periodontal indices in patients on hemodialysis and peritoneal dialysis: cross-sectional study


Study hypothesis

Patients on peritoneal dialysis have better periodontal status than patients on hemodialysis.

Ethics approval

1. Approved 11/06/2014, Ethics committee University hospital center “Sestre milosrdnice” (Vinogradska cesta 29, HR-10000, Zagreb, Croatia; +385 13787111), ref: EP-7326/14-11
2. Approved 12/02/2015, Ethics committee School of Dental medicine, University of Zagreb (Gunduliceva 5, HR-10000 Zagreb, Croatia), ref: 05-PA-26-6/2015.

Study design

Observational cross-sectional single-centre study

Primary study design


Secondary study design

Cross sectional study

Trial setting


Trial type


Patient information sheet

Not available in web format, please use contact details to request a participant information sheet


Periodontal infection in patients with end-stage kidney disease


Before the dialysis procedure patients are examined by the same calibrated examiner. Patients fill a questionnaire about oral hygiene habits, alcohol consumption, smoking habits, education and sign informed consent. Laboratory tests that are usually taken on the day of dialysis are made available to the researcher by the Hospital.

Intervention type



Drug names

Primary outcome measure

Periodontal inflamed surface area (PISA). It is calculated based on bleeding on probing (BOP), clinical attachment level (CAL) and recession (REC) that are performed at six sites on each tooth. PISA is calculated by the on-line calculator available at:

Secondary outcome measures

1. Plaque index (Approximal plaque index API; Lange 1986.): approximal spaces in all four quadrants are measured only vestibular or oral and mark as presence or absence of plaque (+ or -). It is calculated as a percentage by the formula: API= number of sites with plaque (+)/ number of tested sites x 100
2. Periodontal bleeding index (PBI; Saxer and Muhlemann 1975.): there are four stages of bleeding sulcus after probing. All teeth in all four quadrants are probed. In first and third quadrant probing is done only on oral side and in second and fourth quadrant probing is done only on the vestibular side. PBI can be noted as bleeding number (sum of all bleeding values) or as the number of bleeding sites divided by the number of tested sites. Bleeding is provoked with blunt periodontal probe and light pressure from the papilla base to the top of papilla first in distal and then in the mesial sulcus. After 20-30 seconds when one quadrant is probed bleeding intensity is evaluated in four grades. Grade 1: only one point of blood is seen. Grade 2: blood line or several bleeding spots on gingival margin. Grade 3: interdental triangle is bleeding. Grade 4: profuse bleeding immediately after probing of interdental space
3. Periodontal probing depth: on six sites at each tooth-the distance between gingival margin and bottom of the sulcus or periodontal pocket in millimetres
4. Bleeding on probing (BOP; Ainamo and Bay, 1975.): on six teeth surfaces same as periodontal probing depth, without graduation, bleeding after probing is marked as + or -. It is presented as a percentage
5. Gingival recession: defined as the distance from cement-enamel junction till free gingival margin on six sites at each tooth. It is measured in millimetres
6. Clinical attachment level (CAL): is calculated by summing up periodontal probing depth and the distance from the gingival margin to the cementoenamel junction
7. Type of dialysis (hemodialysis or peritoneal dialysis)
8. Confounding variables that are statistically controlled:
8.1 Demographic and vital indicators: age, sex, education, smoking habits, alcohol consumption, height, weight, body mass index, nutritional state
8.2 Nephrological indicators: kidney disease, pharmacotherapy, duration of dialysis, dialysis access, main cardiovascular event
8.3 Dental indicators: self-reported xerostomia, frequency of dental examinations per year, frequency of tooth brushing and flossing, using of interdental brushes, self-reported bleeding during brushing
8.4 Laboratory and biochemical indicators (usually measured in dialysis patients): complete blood count, Kt/V (number used to quantify dialysis treatment adequacy ), CRP (C-reactive protein), albumin in serum, lipidogram test, calcium and phosphorus in serum, PTH (parathormone).

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Aged >18 years
2. Kidney failure
3. Treated with hemodialysis or peritoneal dialysis.

Participant type


Age group




Target number of participants


Total final enrolment


Participant exclusion criteria

1. I-IV level of renal failure
2. Renal transplant patients

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Clinic of Internal Medicine, University Hospital Center Sestre milosrdnice
Vinogradska cesta 29

Sponsor information


School of Dentistry University of Zagreb

Sponsor details

Ulica Ivana Gundulića 5

Sponsor type




Funder type


Funder name

investigator initiated and funded

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Planned publication in a high-impact peer-reviewed journal.

IPD sharing statement:
All data generated or analysed during this study will be included in the subsequent results publication.

Intention to publish date


Participant level data


Basic results (scientific)

Publication list

2020 results in (added 21/08/2020)

Publication citations

Additional files

Editorial Notes

21/08/2020: The following changes have been made: 1. Publication reference added. 2. The final enrolment number has been added from the reference. 14/06/2019: Trial’s existence confirmed by Ethics committee School of Dental medicine, University of Zagreb.