Plain English Summary
Background and study aims
Tooth-colored composite material is nowadays commonly applied in dental practice. Even larger cavities can be filled with this material. For teeth that are severely broken down, however, a full crown is the traditional treatment of choice. This is for instance the case with teeth that are affected by fracture of one of the cusps (a pointed or rounded projection on the chewing surface of a tooth). Despite the longevity of full crowns, a disadvantage of this restoration is that removal of a substantial amount of sound tooth tissue is required. Composite cusp-replacing restorations may provide a tooth tissue saving alternative for the full crown.
Research data show that fracture of a cusp is a common phenomenon. In most cases, cusp fracture occurs in teeth that are weakened by previous decay and restorations. In combination with chewing forces, this may lead to fracture of a cusp. Teeth with cusp fracture can be restored with both direct and indirect composite techniques. Direct composite restorations are made by the dentist in one treatment session and are relatively cheap.
Indirect composite restorations are made in the dental laboratory, which offers better control. The involvement of the dental technician, however, implies two treatment sessions and higher financial costs. It is not known to whether the clinical performance of composite restorations replacing cusps is dependent on the restorative technique.
The purpose of the study is to compare the short and long term clinical performance of direct and indirect cusp-replacing composite restorations.
Who can participate?
Patients with a fractured small back tooth (premolar) without root canal treatment.
What does the study involve?
Patients that participated in this study had a tooth with a fractured cusp. First the tooth was prepared for a cusp-replacing restoration, which means that old restoration material and carious tissue if present- was removed. Second, the tooth was provided with either a direct or indirect composite cusp-replacing restoration. The treatment technique to which a participant was allocated was decided by a process called randomization, which is like a coin toss. After treatment, patients were invited for a check-up after one month and subsequent yearly check-ups.
What are the possible benefits and risks of participating?
The benefits for those taking part are that their fractured tooth will be treated with a tooth tissue saving restoration. Treatment is free of charge. The benefit for future patients is that information on the performance of adhesive restorations for fractured teeth becomes available. It is expected that, based on these results, a choice between direct and indirect restorations can be made.
The main risk of participating is that the performance of adhesive restorations replacing cusps is unknown. In case the result of the treatment with a adhesive restoration appears to be not sufficient, however, the traditional treatment (full crown) is still available.
Where is the study run from?
The study is single-centre and run from the Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
When is the study starting and how long is it expected to run for?
Inclusion of patients started at December 1, 2001 and stopped at April 30, 2007. Follow-up period is 5 years minimum.
Who is funding the study?
Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
Who is the main contact?
Dr Willem Fennis
Dr Willem Fennis
Philips van Leijdenlaan 25
+31 24 361 40 04
Adhesive restorations replacing cusps in fractured teeth: a comparison of minimal invasive direct and indirect techniques - A randomized clinical trial
Cusp fracture of restored posterior teeth is frequently observed in dental practice. The conventional treatment is to restore the tooth with a metal-ceramic crown. Despite the high survival rate of crowns, a disadvantage of this technique is that it requires removal of a large part of the remaining sound cusp to create retention and resistance. It is expected that resin composite restorations do not require extensive mechanical retention for their adhesive nature. They may thereby prevent complications like pulpal damage. Resin composite restorations have been used in Class I and II cavities with success. Long-term data are on adhesive restorations replacing cusps are, however, not available yet. For a long time, it is stated that resin composite is not appropriate as an occlusion-bearing restoration material and it would be valuable to examine whether this assertion is true.
Resin composite restorations can be made with direct and indirect techniques. Direct restorations are preferred for reasons of minimal intervention. They can be made in one treatment session at relatively low costs, without an intermediate cement layer. Indirect restorations are advocated to overcome problems related to shrinkage. Furthermore, the indirect technique offers a higher degree of polymerization and the possibility to shape external surfaces extra-orally. Clinically no significant difference in survival rates of direct and indirect resin composite restorations was found. For adhesive restorations replacing cusps in particular, both direct and indirect techniques are adequate to restore morphology and function, but long-term data are not available.
The objective of this randomized clinical trial (RCT) was to compare the long-term clinical performance of direct and indirect resin composite restorations replacing cusps.
The null hypothesis tested was that there was no difference in survival for direct and indirect restorations.
Committee on Experimental Research on Man of the Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. January 11, 2001, Ref 2001/166
Single centre randomized clinical trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Tooth fracture (dental diseases)
Participants are randomly allocated to a direct resin composite cusp-replacing restoration or a indirect resin composite cusp-replacing restoration.
Primary outcome measure
Difference in long-term survival of direct and indirect resin composite restorations replacing cusps
Secondary outcome measures
Differences between direct and indirect adhesive restorations replacing cusps regarding:
1. Efficacy and (cost) effectiveness
2. Failure mode at restoration level (for instance fracture of restoration) and at tooth level (for instance caries)
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Patient (male and female, minimum age for participation in the study was 18 years) with a fracture of one of the cusps of a vital (no root canal treatment present or necessary) premolar.
Target number of participants
Participant exclusion criteria
1. Premolar with fracture of both cusps
2. Tooth mobility grade III (>1 mm horizontal tooth mobility and vertical tooth mobility)
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Philips van Leijdenlaan 25
Radboud University Nijmegen Medical Centre (Netherlands)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)
Kuijs RH, Fennis WM, Kreulen CM, Roeters FJ, Creugers NH, Burgersdijk RC, A randomized clinical trial of cusp-replacing resin composite restorations: efficiency and short-term effectiveness., Int J Prosthodont, 19, 4, 349-354.
Fennis WM, Kuijs RH, Roeters FJ, Creugers NH, Kreulen CM, Randomized control trial of composite cuspal restorations: five-year results., J. Dent. Res., 2014, 93, 1, 36-41, doi: 10.1177/0022034513510946.