Condition category
Oral Health
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status

Plain English Summary

Background and study aims
Restorations in compromised endodontically treated teeth are aimed to (protect the remaining dental tissue from fracture, preventing the return of sepsis to the root canal system, as well as compensating for lost dental structures).
There are several ways to restore compromised endodontically treated teeth, one of them called post and core.
Several factors affect the fracture resistance of teeth restored with post and core: (post Length, post diameter, post design, post material, post fitting, core material, cement adhesion).
Fibreglass reinforced resin posts are often prefabricated posts, limiting their fitting of the channel's precise shape.
Even though the low elastic modulus of Fiber posts, but it,s elastic modulus still higher than dentine once about three times. So in our research, we looking for material has an elastic modulus more closely to the dentine once, and can be milled with CAD/CAM.
Recently a new dental material is introduced Poly Ether Ketone Ketones Called (PEKK), this material has similar characteristics to human bone, shock absorbent, lightweight.
The aim of this study is to compare the survival rates between the three groups: one-piece milled post and core from (PEKK), one-piece milled post and core from fibre-reinforced composite blocks and prefabricated fibre posts.

Who can participate?
Adults with destroyed lower premolars

What does the study involve?
Chosen teeth are randomly allocated into three groups for restorations supported with either one-piece milled post and core from (PEKK)or one-piece milled post and core from fibre reinforced composite blocks or prefabricated fibre posts. All teeth are assessed clinically at 3, 6, and 12 months and radiographically at 6 and 12 months after treatment.

What are the possible benefits and risks of participation?
The treatment may introduce a new material for fabricating posts and cores.
There are no known risks to participants as any failed treatments will be re-done using another method.

Where is the study run from?
Department of fixed prosthodontic Dentistry, Tishreen University, Lattakia, Syria)

When is the study starting and how long is it expected to run for?
May 2019 to December 2021

Who is funding the study?
Tishreen University, Syria

Who is the main contact?
Dr Naif Ghanem,
Dr Naser Baherli,

Trial website

Contact information



Primary contact

Dr Naif Ghanem


Contact details


Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Evaluating the success of post and core system fabricated by Polyetherketoneketone (PEKK) material in restoring endodontically treated teeth: a randomized controlled trial


PEKK_ post and core_ endodontically treated teeth

Study hypothesis

Null hypothesis: There are no differences in survival rates between the three groups: one-piece milled post and core from (PEKK), one-piece milled post and core from fiber reinforced composite blocks and prefabricated fiber posts.

Alternative hypothesis: There are differences in survival rates between the three groups: one-piece milled post and core from (PEKK), one-piece milled post and core from fiber reinforced composite blocks and prefabricated fiber posts.

Ethics approval

Approved 02/04/2019, The Institutional Review Board of Tishreen University (Tishreen University, Faculty of Dentistry, Department of Pediatric Dentistry), No. 2164

Study design

Randomized three parallel-groups clinical trial

Primary study design


Secondary study design

Randomised parallel trial

Trial setting


Trial type


Patient information sheet

No participant information sheet available


damaged endodontically treated lower premolars with 2 or less remaining
cavity walls that is need post and core


A randomized three parallel-groups clinical trial was designed to evaluate the differences in survival rates between the three groups:

Group 1: one-piece milled post and core from (PEKK)
Group 2: one-piece milled post and core from fibre-reinforced composite blocks.
Group 3: prefabricated fiber posts (control group)

According to the patient identification number, restricted random allocation was performed by blocking with a block length of 3 and 6 based on a the website ( to achieve balance between groups in size. Double blinding will be used (patient and examiner).

The control group is the group of prefabricated fiber posts.

The primary endpoint was the loss of restoration for any reason. Secondary endpoints were tooth loss, post debonding, post fracture, vertical or horizontal root fracture, endodontic or periradicular conditions requiring endodontic retreatment, secondary
caries and failure of core build-up, and loss of restoration because of technical failures. The patients were recalled at 3, 6, and 12 months.

Intervention type



Drug names

Primary outcome measure

The loss of restoration for any reason, conducted by using of an explorer at 3, 6, and 12 months post-treatment and periapical radiographic examination performed by use of a paralleling technique at 6 and 12 months post-treatment

Secondary outcome measures

Conducted by visual inspection at 3, 6, and 12 months post-treatment
1. Tooth loss
2. Post debonding
3. Post fracture
4. Vertical or horizontal root fracture
5. Endodontic or periradicular conditions requiring endodontic retreatment
6. Secondary caries
7. Failure of core build-up
8. Loss of restoration because of technical failures

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Patients older than 18 years
2. Patients are required to have one mandibular premolar for which endodontic treatment is indicated
3. The remaining cavity walls of the premolar after endodontic treatment two or fewer
4. No or treated periodontitis with a maximum probing depth of 4 mm and no bleeding on probing
5. Tooth mobility not more than score 1
6. The premolar are required to be in occlusal function with a natural tooth following restoration and none are used as abutments for fixed or removable prostheses
7. A willingness to return for a follow-up examination for at least one year

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Tooth will aim to serve as an abutment for fixed or removable prostheses
2. Medical contraindications to dental treatment
3. Poor oral hygiene
4. Teeth with failed endodontic therapy
5. Patients with severe parafunctional habits

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Tishreen University
Faculty of Dentistry

Sponsor information


Tishreen University

Sponsor details

+963 (0)41420291

Sponsor type




Funder type


Funder name

Tishreen University

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

The results will be published in one of the prosthodontic journals which are related to the Scopus group.
The results that will be published are:
1. Survival rates of (PEKK) posts and cores
2. A comparative study about two materials that are used to fabricate one-piece milled posts and cores

IPD sharing statement:
The datasets generated during and/or analysed during the current study are not expected to be made available due to confidetiality

Intention to publish date


Participant level data

Not expected to be available

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

14/10/2019: Trial’s existence confirmed by Tishreen University