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

Plain English Summary

Background and study aims
Tooth wear (TW) is an umbrella term that includes various subforms that result of different physical and chemical impacts that act on tooth surfaces. Patients with worn teeth seek professional help for tooth pain and sensitivity, chewing problems and appearance problems.
Although several treatment types are at hand, there has been no long term follow-up study on fixed restorations (permanently attached in patients with excessively worn teeth. The reasons for this are many and could include difficulties in recruiting enough patients, or the challenging nature of the treatment as it may be associated with a high risk of failure.
Metal ceramic restorations are considered the standard treatment for patients treated with fixed restorations including patients with excessively worn teeth. Adverse appearance concerns regarding grayish discoloration and possible exposition of the metal framework margin are known drawbacks. As an alternative, several different all-ceramic materials have been developed that are attractive for dental use because of their appearance and compatibility with living tissue. Developments in ceramic materials have allowed more widespread application of all-ceramic restorations over the past 20 years. The clinical advantage of the modern ceramic monolithic restorations (restorations that consist of only one layer without external porcelain layer) is defined by a significantly reduced material thickness in comparison with veneered restorations (restorations that consist of two layers including external porcelain layer).
The primary aim of this study is to evaluate and compare the 3-5 years clinical performance and success rate of two all ceramic crowns when reconstructing extensively worn teeth. The secondary aim is to examine the opinion of each patient by using two scales/questionnaires.

Who can participate?
Adults aged 17 – 65 years with tooth wear

What does the study involve?
Participants are randomly allocated to one of two groups. Those in the first group receive IPS e.max press crowns, and those in the second group receive monolithic BruxZir crowns. These are permanently attached restorations to treat tooth wear. Participants are followed up with clinical photographs and questionnaires at appointments 2-4 weeks and 1, 3 and 5 years after the treatment is completed.

What are the possible benefits and risks of participating?
Participants may benefit from the investigation, treatment and follow up, and are able to provide feedback regarding this. The risk of complications is very small/negligible, the same as with any other prosthodontic treatment.

Where is the study run from?
National Dental Eastman Institute (Folktandvården Eastmaninstitutet) (Sweden)

When is the study starting and how long is it expected to run for?
March 2012 to December 2018

Who is funding the study?
1. Folktanvarden Stockholm län AB (Sweden)
2. Swedish dental research (SOF) and Karoliska institutet (Sweden)

Who is the main contact?
Mrs Wedad Hammoudi (Public)

Trial website

Contact information



Primary contact

Mrs Wedad Hammoudi


Contact details

Dalagatan 11
11324 Stockholm



Additional contact

Dr Jan-Ivan Smedberg


Contact details

Dalagatan 11
11324 Stockholm



Additional contact

Prof Mats Trulsson


Contact details

Karolinska institutet- Dental high school
14152 Huddinge

Additional identifiers

EudraCT number number

Protocol/serial number

Karolinska institutet/Swedish dental research (SOF) project nr 14101913 and Folktandvarden Stockholm project nr.7057

Study information

Scientific title

Randomized controlled clinical trial compairing monolithic translucent zirconia and emax press singel crowns used for prosthetic treatment of extensively worn dentition


Study hypothesis

All ceramic monolithic IPS e.max press and monolithic BruxZir crowns have the same strength and success rate but BruxZir crowns are less aesthetic when used to reconstruct extensively worn dentition.

Ethics approval

Regional Ethical Review Board Stockholm Sweden, 15/08/2012, ref: 2012/263-31/2

Study design

Single center double blind randomised clinical trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

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


Tooth wear


Participants are randomized into two groups according to a randomization list generated by a website (
The first group receives IPS e.max press (glass infiltrated lithium disilicate) crowns and the second group receives monolithic BruxZir Crowns (translucent zirconium oxide).
As a standard procedure, diagnostic mock-up and laboratory fabricated temporary bridges precede the prosthetic therapy. Increasing the vertical dimension is only performed when needed.
All restorations are adhesively luted and are examined at 2-4 weeks (baseline), 1 year, 3 years, 5 years after completion of the treatment.

Intervention type



Drug names

Primary outcome measure

1. Clinical performance and success rate of the crown is assessed using clinical photographs taken 2-4 weeks (baseline) and follow up visits 1, 3 and 5 years after completion of the treatment.
2. Technical outcome of the reconstructions is examined using the united States Public Health Service (USPHS) criteria at 2-4 weeks (baseline) and follow up visits 1, 3 and 5 years after completion of the treatment.

Secondary outcome measures

The subjective opinion of each patient is measured using the international OHIP and OAS scales at 2-4 weeks (baseline) and 1, 3 and 5 years after completion of the treatment.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Aged 17-65 years.
2. At least 10 teeth in the upper and lower arches
3. Good periodontal status
4. At least TW > grade 2 on any tooth surface on at least four teeth in the same arch according to Smith and Knight’s tooth wear index (TWI)

Participant type


Age group




Target number of participants

Max 116 and min 60 patients

Total final enrolment


Participant exclusion criteria

1. Patients with fixed and removable partial dentures
2. Patients with severe TMJ disorders
3. Patients with gross malocclusion
4. Patients with mineralisation disorders
5. Patients with neurologic, psychiatric, or sleep disorders

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

National Dental Eastman Institute (Folktandvården Eastmaninstitutet)
Dalagatan 11
113 24

Sponsor information


National Dental Eastman Institute (Folktandvården Eastmaninstitutet)

Sponsor details

Dalagatan 11
113 24
+46 8 123 165 00

Sponsor type

Hospital/treatment centre



Funder type

Hospital/treatment centre

Funder name

Folktanvarden Stockholm län AB

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Swedish dental research (SOF) and Karoliska institutet

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: The datasets generated during and/or analysed during the current study will be stored as a file in a non-publically available repository; Folktandvarden Stockholm data base. Permission for this file is obtained from data inspection board at Folktandvarden Stockholm. There are only three persons who have access to this file; the researcher performing the clinical study (Wedad Hammoudi), the research assistant and the head of the department for prosthetic dentistry at Eastman Institutet as he is the main supervisor (Jan-Ivan Smedberg). Each patient has a specific number in that file. The lists or results to be shared with the statistician who is going to analyse the data do not contain patients' names and identification numbers, they consist only of numbers (i.e. coded lists). Those coded lists and results will be stored as a file at Karolinska Institutet (ELN) according to their new rules concerning all researchers at that institute. Informed consent is obtained from all individual participants included in the study. Participants are informed in the consent that all results as well as all complications will be registered in coded form and responses and results will be processed so that unauthorized persons cannot share them. The results will be stored for about 15 years.

Intention to publish date


Participant level data

To be made available at a later date

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

18/12/2019: The following changes have been made: 1. The overall trial end date has been changed from 30/12/2018 to 19/12/2019. 2. The intention to publish date has been changed from 15/12/2019 to 31/03/2020. 4. The total final enrolment has been added.