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
Losing teeth is an inevitable part of the aging process for some people. The gaps left by missing teeth can cause problems with eating or speech, as well as affecting appearance, which can be distressing for the sufferer. Losing all of the molars (back teeth used for grinding food) in the upper or lower jaw can be treated in different ways. The main options being replacement with removable dentures (false teeth), dental implants (metal posts which are screwed directly into the jaw bone in order to support replacement teeth) or shortened dental arch (SDA) treatment. SDA is a cost-effective treatment in which only the missing teeth towards the front of the mouth are replaced using fixed bridges (a way of attaching the artificial tooth (or teeth) to a permanent (natural) tooth. There is currently a lack of evidence as to which of these techniques is more beneficial in the long-run. The aim of this study is to compare the effects of SDA and removable partial dentures on future tooth loss and oral health in the long-run.

Who can participate?
Adults over 35 years old who have asked for prosthetic dental treatment who are missing all molars in one jaw and with at least both canines and one premolar left on each side

What does the study involve?
Participants are randomly allocated to one of two groups. Those in the first group are given removable partial dentures to replace their missing molars. Those in the second group receive SDA treatment to replace only the essential premolars (teeth between the canines and molars). All participants are examined after 8 weeks, 6 months, 1 year and then every year after the treatment for 5 years. After this, participants have dental exams at 8, 10 and 15 years after treatment. During these examinations dental and oral health are recorded as well as any further tooth loss.

What are the possible benefits and risks of participating?
There is no direct benefit for participants taking part in the study, although participants will receive financial support and compensation for the dental treatments and examinations. There are no risks of taking part other than the general risks associated with having dental surgery.

Where is the study run from?
The study is run from the Departments of Prosthetic Dentistry at the Universities of Berlin, Bonn, Dresden, Freiburg, Giessen, Greifswald, Jena, Kiel, Leipzig, Mainz, Munich, Wuerzburg, Witten and Homburg.

When is the study starting and how long is it expected to run for?
October 2000 to December 2022

Who is funding the study?
German Research Foundation (Germany)

Who is the main contact?
Professor Michael Walter

Trial website

Contact information



Primary contact

Prof Michael Walter


Contact details

Fetscherstr. 74
+49 351/458 2706

Additional identifiers

EudraCT number number

Protocol/serial number

DFG WA 831/2-1 to 2-6

Study information

Scientific title

Randomised multicentre study of prosthetic treatment options for shortened dental arch



Study hypothesis

Over the last 20 years a mechanistic attitude correlated with a lack of longitudinal controlled randomised trials regarding the question of prosthetic treatment after tooth loss. The need assessment considered the replacement of all missing teeth by fixed or removable partial dentures or dental implants as a necessity especially in cases of shortened dental arches. Modern prosthetic concepts distinguish between different dimensions of need (normative need, perceived need) being well aware of the fact that perceived need has been under-represented in the past. An innovative sight puts a higher emphasis to the subjective components of need assessment and outcome measurement. Generally three adverse effects of non-replacement of molars were postulated: temporomandibular joint (TMJ) disorders, tooth migration/overeruption, insufficient chewing ability. However, no evidence based on randomised trials has been provided concerning the incidence of the adverse side effects mentioned above, nor is there high-level evidence regarding a benefit of removable dentures for molar replacement. On the contrary removable partial dentures are compromised by a high incidence of adverse side effects such as plaque accumulation and peridontal breakdown.

Among therapeutic alternatives, an approach with a limited restoration goal focused on incisors, canines and premolars (shortened dental arch [SDA] concept) has been described and implemented although discussed controversially. Within this concept, fixed partial dentures are used for tooth replacement of which a superior performance compared with removable partial dentures has been reported. The multi-centre study was initiated in 2000 because evidence was lacking concerning the benefit of different therapeutic options regarding the preservation of oral health, oral health related quality of life, patients satisfaction, absence of discomfort, satisfactory chewing ability and aesthetic satisfaction. Public health aspects of the study lie in the fields of health economics, avoidance of over-treatment, and therapy guidelines on a population based level.

Two prosthetic therapy arms will be compared:
1. The replacement of posterior teeth at last up to the first molar by removable partial dentures
2. Prosthetic treatment according to the shortened dental arch concept. To avoid removable partial dentures, posterior teeth are replaced up to the second premolar by fixed restorations, if necessary. Molars are not replaced.

The aim of this trial is to test the hypothesis that the treatment outcome varies depending on the treatment concept (fixed versus removable prostheses) in the therapy of patients with missing molars.

Ethics approval

Ethics Committee of the Medical Faculty of the Technical University of Dresden (Ethikkommission der Medizinischen Fakultät der Technischen Universität Dresden). Date of approval: 19/04/1999 (ref: EK 260399)

Study design

Multi-centre randomised controlled clinical trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting

Not specified

Trial type


Patient information sheet

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


Tooth loss/ molar replacement


Control group (Therapy A): The molar replacement by removable partial dentures, carried out using fixed crowns and bridges as anchor for removable dentures

Intervention group (Therapy B): Restorations according to the SDA concept, with only fixed restorations or no restoration at all. The maximum extension reached up to the second premolar, and no molars were replaced. All restorations were made according to a standardized procedure (SOP) given by the study protocol.

Standard gold alloys and dental ceramics were used for fixed restorations, base metal alloys for the removable denture frameworks.

Intervention type



Not Specified

Drug names

Primary outcome measure

Further tooth loss is measured at 5, 8, 10 and 15 years

Secondary outcome measures

The following will be assessed at baseline (4-8 weeks after insertion), 6 month, then annually from Year 1 to 5, and further at 8, 10 and 15 years:
1. Clinical:
1.1. Crown/root caries
1.2. Abrasion (Index 0-4)
1.3. Interdental spacing in the anterior region (Index 0-3)
1.4. Sensibility (+/-)
1.5. Periodontitis/Gingivitis: Plaque-index (index 0-3), probing depth (6 point measurement in mm), attachment loss (6 point measurement in mm), bleeding on probing (BOP)(+/-), tooth mobility (index 0-3), mucosa lesions (California Dental Association [CDA] Criteria)
2. Clinical dysfunction index: Muscle pain via palpation (m. masseter pars profunda et superficialis, m. temporalis pars posterior et anterior, m. pterygoideus medialis et lateralis)
3. Range of movement (mm): maximal opening
4. TMJ function: Description of pain on movement/path of movement, palpation/auscultation
5. Technical (according to the CDA criteria): Treatment performance, preparation form, marginal fit, occlusion static/dynamic in µm, proximal contacts (shape/ strength)
6. Technical performance (according to the CDA criteria): Evaluation of used materials, prosthesis and bridge design, saddle extension, possibility of dental hygiene

9. Oral health related quality of life (OHIP-Questionnaire): Measure of self reported dysfunction, discomfort and disability attributed to oral conditions
10. Dworkin Index Axis II (questionnaire): Assessment of psychological distress and psychosocial dysfunction including questions regarding:
10.1. Graded chronic pain severity
10.2. Depression
10.3. Vegetative symptoms and somatization subscales of the SCL-90-R developed by Derogatis and others
10.4. Jaw disability checklist

The CDA Criteria are used according to the Guidelines for the Assessment of Clinical Quality and Professional Performance of the California Dental Association:

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Patients over 35 years of age, who requested prosthetic treatment with a minimum dentition of both canines and one premolar per side preserved in at least one jaw (Kennedy class I). A dentition including all anterior teeth up to the second premolar on both sides in one jaw was defined as maximum
2. Rejection of implant treatment by the patient
3. Patients with general health according to American Society of Anesthesiologists (ASA) classification group one ore two
4. All abutment teeth must be free of periodontal disease (pocket depth less or equal 4 mm, tooth mobility <= grade 2, mean plaque index <= grade 2, bleeding on probing at all teeth <=25 %) and caries
5. Caries free adjacent teeth
6. Sufficient treatment of the opposite jaw, extending the dentition depending on the randomized treatment option up to the second premolar or the first molar

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Patients with alcohol or drug addiction
2. Mentally disordered patients
3. Patients with TMJ disorders
4. Dysgnathic patients with Angle class II or III
5. Patients who have received or need orthodontical treatment
6. Patients who have been already sufficiently treated
7. Patients who do not accept a removable deture
8. Patients who demand the replacement of all molars
9. Patients with general health American Society of Anesthesiologists (ASA) classification group four

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

University Hospital Carl Gustav Carus
Department of Prosthetic Dentistry Technische Universität Dresden Dental School Fetscherstraße 74

Trial participating centre

Charité – Universitätsmedizin Berlin
CC3 - Charité Center for Dental and Craniofacial Sciences Department of Prosthodontics Geriatic Dentistry and Craniomandibular Disorders Campus Benjamin Franklin Aßmannshauser Straße 4

Trial participating centre

University of Bonn
Department of Prosthodontics Preclinical Education and Dental Materials Science Welschnonnenstr.17

Trial participating centre

Albert-Ludwig University of Freiburg
Department of Prosthetic Dentistry Hugstetter Str.55

Trial participating centre

Justus-Liebig University of Giessen
Department of Prosthetic Dentistry Schlangenzahl 14

Trial participating centre

Ernst-Moritz-Arndt University of Greifswald
Department of Prosthodontics, Gerodontology and Biomaterials Dental School Rotgerberstr. 8

Trial participating centre

Friedrich-Schiller University of Jena
Department of Prosthetic Dentistry and Dental Material Science An der alten Post 4

Trial participating centre

Christan-Albrechts University
Department of Prosthetic Dentistry Arnold-Heller-Str. 16

Trial participating centre

University of Leipzig
Department of Prosthetic Dentistry and Dental Material Science Nürnberger Str. 57

Trial participating centre

Johannes-Gutenberg University of Mainz
Department of Prosthetic Dentistry Augustusplatz 2

Trial participating centre

Ludwig-Maximilians University
Department of Prosthetic Dentistry Goethestr. 70

Trial participating centre

Julius-Maximilians University of Würzburg
Department of Prosthetic Dentistry Pleicherwall 2

Trial participating centre

Witten-Herdecke University
Department of Prosthetic Dentistry Alfred-Herrhausen-Str. 50

Trial participating centre

Saarland University Hospital and Saarland, University Faculty of Medicine
Department of Prosthetic Dentistry Geb. 71N

Sponsor information


German Research Foundation (Deutsche Forschungsgemeinschaft)

Sponsor details

Kennedyallee 40
Sponsorship valid until 2010
+49 228/885 1

Sponsor type




Deutsche Gesellschaft für Prothetische Zahnmedizin und Biomaterialien e.V. (DGPRo)

Sponsor details

Zahnklinik der Sozialstiftung Bamberg
Buger Straße 82
+49 951 700 362 60

Sponsor type




Deutsche Gesellschaft für Zahn-, Mund- und Kieferheilkunde (DGZMK)

Sponsor details

Liesegangstr. 17 a
+ 49 2 11 / 61 01 98 0

Sponsor type




Cendres+Métaux SA

Sponsor details

Rue de Boujean 122
+41 58 360 20 00

Sponsor type




Deutsche Forschungsgemeinschaft

Sponsor details

Sponsor type

Not defined



Funder type


Funder name

German Research Foundation (Deutsche Forschungsgemeinschaft)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Planned publication in peer reviewed journals.

Intention to publish date


Participant level data

Not expected to be available

Basic results (scientific)

Publication list

1. 2010 protocol in
2. 2010 results in
3. 2012 results in
4. 2014 results in
5. 2014 results in
6. 2014 results in
7. 2014 results in

Publication citations

  1. Protocol

    Luthardt RG, Marré B, Heinecke A, Gerss J, Aggstaller H, Busche E, Dressler P, Gitt I, Hannak W, Hartmann S, Heydecke G, Jahn F, Kern M, Mundt T, Pospiech P, Stark H, Wöstmann B, Walter MH, The Randomized Shortened Dental Arch study (RaSDA): design and protocol., Trials, 2010, 11, 15, doi: 10.1186/1745-6215-11-15.

  2. Results

    Walter MH, Weber A, Marré B, Gitt I, Gerss J, Hannak W, Hartmann S, Heydecke G, Huppertz J, Jahn F, Ludwig A, Mundt T, Kern M, Klein V, Pospiech P, Stumbaum M, Wolfart S, Wöstmann B, Busche E, Böning K, Luthardt RG, The randomized shortened dental arch study: tooth loss., J. Dent. Res., 2010, 89, 8, 818-822, doi: 10.1177/0022034510366817.

  3. Results

    Wolfart S, Marré B, Wöstmann B, Kern M, Mundt T, Luthardt RG, Huppertz J, Hannak W, Reiber T, Passia N, Heydecke G, Reinhardt W, Hartmann S, Busche E, Mitov G, Stark H, Pospiech P, Weber A, Gernet W, Walter MH, The randomized shortened dental arch study: 5-year maintenance., J. Dent. Res., 2012, 91, 7 Suppl, 65S-71S, doi: 10.1177/0022034512447950.

Additional files

Editorial Notes

29/01/2016: Publication reference and plain English summary added. 28/01/2016: The overall trial end date has been extended from 31/12/2010 to 31/12/2022. As a result of this, the primary and secondary outcome measures will also be measured at 8, 10 and 15 years (in addition to the original timepoint of 5 years). All participating trial participating centres have now been included on the record. Additionally, the sponsors DGPRo, DGZMK and Cendres+Metaux have been added, providing sponsorship since 2010.