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
Taking impressions of teeth (dental impressions) are vital for all dental restoration surgeries. Traditionally, dentists take impressions by asking the patient to “bite down” on synthetic putty, so that a 3D mold of the teeth could be made. In recent years, the use of computerised systems has been used more and more in dentistry. Many dentists now use digital impression and scanning systems to take accurate impressions of the teeth, which are considered to be a faster and more accurate way of taking dental impressions. The aim of this study is to find out whether dental crowns (a tooth-shaped "cap" that is placed over a tooth) made using traditional impression methods (putty) or a digital impression system fit better in the patient.

Who can participate?
Healthy adults who are in need of one or two crowns on pre-molar teeth.

What does the study involve?
Two dental crowns are made for each tooth that requires a crown, one made from dental impressions taken traditionally (using putty) and one made using digital impression techniques. The fit of each crown is determined using a microscope. How well each of the crowns fit is then compared.

What are the possible benefits and risks of participating?
A benefit of taking part in the study is that participants are able to receive their dental crown at a discounted price. The risks of participating are minor and include the general risks associated with dental surgery.

Where is the study run from?
Universidad Complutense de Madrid (Spain)

When is the study starting and how long is it expected to run for?
September 2010 to June 2012

Who is funding the study?
Straumann Implant system (Spain)

Who is the main contact?
Miss Cristina Zarauz

Trial website

Contact information



Primary contact

Miss Cristina Zarauz


Contact details

Tandheelkunde Boerhaave
Dintelstraat 60
1078 VV

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions


Study hypothesis

Null hypothesis: There is no difference in accuracy between the fit of the crowns fabricated with the digital impression and the conventional impression.

Ethics approval

Comité Ético de Investigaciones Clínicas CEIC (Ethical commette for clinical investigations, Spain), 02/03/2011, ref: E-09/377

Study design

Observational case crossover study

Primary study design


Secondary study design

Case crossover study

Trial setting


Trial type


Patient information sheet


Accuracy of fit of crowns fabricated by 2 different impression systems, for healthy patients.


Each tooth included in the study was the investigation unit (or specimen). Each tooth was prepared for crown, and 2 impressions were taken on each tooth (one digital & one conventional). 2 crowns were produced for each tooth, one with the conventional impression, and one with the digital impression.
These 2 crowns were tried on the prepared tooth, to replicate the misfit, and were left embedded in the replicated misfit, to be taken to process to the lab. Through embedding, this very thin layer of silicone (50 microns sometimes), is better stabilised. A third crown was produced by the conventional impression system (as it is still gold standard), to cement after we had done accuracy testing. Both impressions are commercially available and CE marketed and routinely employed as a standard of care. Added burden mounted to 5-10 minutes of extra chair time, as 2 impressions were taken, instead of one (impressions have no negative effect on the patient whatsoever), and later, at timepoint 2, it meant a total of 10 more minutes for the patient, as we did the accuracy testing before cementation of the final crown.

Intervention type



Drug names

Primary outcome measure

Marginal misfit of zirconia-ceramic crowns measured in micrometers between 3 and 8 days after the replication of the fit.

Secondary outcome measures

Internal fit of zirconia-ceramic crowns measured in micrometers between 3 and 8 days after the replication of the fit.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. In need of one or two (if located in contra-lateral quadrants and opposing arches) single crowns on pre-(molar) teeth
2. Subject tooth free of clinical symptoms
3. No requirement for additional endodontic treatment expressed by the presence of a periapical radiolucency around an endodontically treated tooth or a root canal filling <3 months
4. Adequate level of oral hygiene expressed by the absence of signs of periodontal inflammation, bleeding on probing and periodontal pocket depth <4 mm

Participant type


Age group




Target number of participants

26 crowns in the 21 patients.

Participant exclusion criteria

1. Advanced periodontitis affecting the mobility of the teeth (mobility degree 2 or higher)
2. Clinical history of bruxism
3. Pregnant or lactating females
4. Marginal preparation situated deeper than 1 mm subgingival

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Universidad Complutense de Madrid
Plaza de Ramón y Cajal 3

Sponsor information


Straumann Implant system

Sponsor details

Edificio Arroyo - A
Avda. de Bruselas
38 - Planta 1

Sponsor type




Funder type


Funder name

Straumann Implant System

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

The research is accepted for publication in the Journal for Clinical Oral Investigations.

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

2015 results in

Publication citations

Additional files

Editorial Notes

27/11/2015: Publication reference added.