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
Dental implants are a treatment to replace lost teeth. At the time of tooth loss, the jaw bone begins to atrophy (waste away). Standard diameter implants need a considerable amount of bone around them. Faced with a situation of bone atrophy, the surgeon has the option to reconstruct the bone through bone grafts to place standard implants or take advantage of the remaining bone and place implants with a smaller diameter. Implants with a reduced diameter are less resistant than standard diameter implants, so their use is somewhat controversial. One way to avoid fractures of these small diameter implants is to use stronger materials. A few years ago, the researchers began using a titanium-zirconium alloy (Roxolid) that is more resistant. In addition to its higher strength, it is more biocompatible (less harmful to the body) than other alloys. Small diameter implants can be used to safely replace anterior (front) teeth. Its use in posterior areas (back teeth) or in sections of two or more teeth requires more research. The aim of this study is to assess the survival and success of a treatment for an area of three or four missing teeth using a bridge supported by two small diameter implants made of titanium-zirconium.

Who can participate?
Patients aged 18 and over with an area of three or four missing teeth

What does the study involve?
Two titanium-zirconium narrow-diameter implants are placed under local anaesthetic. Only minor bone regeneration or soft tissue grafting is performed if needed. The crowns are placed after at least 8 weeks of healing. The success and survival rate of the implants is assessed 12 months after the final restoration.

What are the possible benefits and risks of participating?
Participants receive innovative but safe treatment. Participants also benefit from a reduced cost of treatment. The small diameter implants have been tested before and no different surgical or prosthetic complications are anticipated than in the placement of standard diameter implants.

Where is the study run from?
Universitat Internacional de Catalunya (Spain)

When is the study starting and how long is it expected to run for?
December 2011 to July 2021

Who is funding the study?
1. Universitat Internacional de Catalunya (Spain)
2. Institut Straumann AG (Switzerland)

Who is the main contact?
1. Dr Jose Nart
2. Dr Pablo Altuna

Trial website

Contact information



Primary contact

Dr Pablo Altuna


Contact details

Josep Trueta s/n
Sant Cugat del Vallès



Additional contact

Dr José Nart


Contact details

Josep Trueta s/n
Sant Cugat del Vallès

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Prospective clinical study of Straumann NNC dental implants for the treatment of partially edentulous patients


Study hypothesis

The hypothesis is that titanium-zirconium narrow diameter implants are a less invasive and successful when used in partially edentulous patients. Titanium-zirconium is a relatively new alloy used to manufacture dental implants. It is considered stronger than TCp, but clinical studies using narrow-diameter implants with this material are scarce.

Ethics approval

Ethics board of Clinical Investigations of the Faculty of Dentistry, Universitat Internacional de Catalunya (Comitè Ètic d'Investigació Clínica (CEIC) of the Clinica Universitària d'Odontologia (CUO), Universitat Internacional de Catalunya, Barcelona), 16/07/2012, ref: IMP-ECL-2012-01

Study design

Prospective clinical trial of a cohort study with a follow-up from 1 year to 5 years

Primary study design


Secondary study design

Cohort study

Trial setting


Trial type


Patient information sheet

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


Partially edentulous patients, missing 3 or four teeth in both jaws


Thirty patients with partial edentulism (missing 3 or 4 teeth from second premolar to second premolar of both jaws) will be recruited for the study at the School of Dentistry’s Clinic, Universitat Internacional de Catalunya, Barcelona. Two titanium-zirconium alloy (Roxolid (R)) narrow-diameter implants will be placed in each patient under local anesthesia. Rehabilitation with a bridge of 3 or 4 crowns. Only minor bone regeneration or soft tissue grafting would be performed if needed. The crowns would be placed after at least 8 weeks of healing.

Intervention type



Drug names

Primary outcome measure

Success and survival rate of Straumann NNC implants 12 months after final restoration:
1. The success rate will be assessed according to the criteria of Buser (Buser et al., 1991):
1.1. No detectable clinical mobility (hand testing)
1.2. No radiolucency surrounding the total surface of the implant
1.3. No persistent pain refractory to medical therapy
1.4. No recurrent peri-implant infection
2. A surviving implant is an implant that is in place at the time of evaluation

Secondary outcome measures

Measured after 1 year, 3 years and 5 years:
1. Radiological measurements of the crestal bone level (mesial and distal), with bite registration and paralleling technique
2. Patient satisfaction and dentist satisfaction, measured using VAS
3. Periodontal evaluation: clinical attachment level, bleeding on probing, plaque index, pocket probing depth
4. Vestibular bone stability, measured using a small field CBCT
4. Survival, success and complications of the prostho treatment

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Patients ≥18 years of age
2. Patients in need of multiple teeth restoration in the maxilla or mandible, of incisors, canines and bicuspids
3. Patients with narrow ridges where conventional implants with a diameter of 4.1 mm cannot be used (< 6 mm)
4. Patients with a full mouth plaque according to O’Leary ≤ 25% at time of surgery

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Patients with any conditions or circumstances which would interfere with the requirements for oral surgery
2. Patients allergic to any implant metallic component
3. Patients needing major bone regeneration techniques
4. Patients where the ridge allows the restoration with a conventional implant diameter of 4.1 mm

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Universitat Internacional de Catalunya
Josep Trueta s/n
Sant Cugat del Vallès

Sponsor information


Universitat Internacional de Catalunya

Sponsor details

Josep Trueta s/n
Sant Cugat del Vallès
+34 (0)935 042 000

Sponsor type




Funder type


Funder name

Universitat Internacional de Catalunya

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Institut Straumann AG (Switzerland)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Publication of 1-year, 3 years and 5 years results

IPD sharing statement
The datasets generated during and/or analysed during the current study are/will be available upon request from Dr Pablo Altuna. After written request and after the 5 year results publication (December 2021), data could be shared after evaluating the credentials of the soliciting investigator and his/her Institution. After acknowledging the written request, authorization by the Dean and/or Research Vice-Dean must be obtained to hand out the requested datasets. All datasets would be blinded regarding patient identification. All patients have signed a proper study informed consent.

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes