Clinical Trial: Novel Use of 2-unit Cantilever Resin-bonded Bridges for Replacing Missing Molar Teeth - a Randomized Clinical Trial

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: Novel Use of 2-unit Cantilever Resin-bonded Bridges for Replacing Missing Molar Teeth - a Randomized Clinical Trial

Brief Summary:

Tooth replacement is a significant issue in the World and while dental implants and conventional bridges have been used to replace missing teeth, dental implants are too expensive for many and conventional dental bridges are destructive to supporting tooth tissue.

Resin-bonded bridges (RBBs) are a conservative and cost effective replacement option that involves minimal tooth preparation, leaving the majority of the tooth intact. They are secured in place with an adhesive cement, which is bonded to the outer enamel layer. Clinical audit of these prostheses at the University of Hong Kong shows two-unit RBBs to have some of the highest success rates in the dental literature for the replacement of missing premolar and incisor teeth. However, for the replacement of molar teeth, two-unit RBBs are not performed, as established protocol and recognised texts contraindicate their use due to concerns with tipping or drifting of supporting teeth. Replacement of a single missing molar tooth can be with a three-unit, fixed-fixed (single-piece casting) or three-unit, fixed-movable (two-part casting). However, the fixed-fixed option has a higher debond failure rate than two-unit RBBs and therefore, at this centre, a modified, 3-unit fixed-movable design is used. This two-part casting allows for minor, independent movements of the supporting teeth and thereby aims to reduce stresses between them and, similarly, reduce de-bonding forces. This has the potential for greater longevity and easier long-term maintenance as if the major part of the bridge debonds it can be recemented.

The aim of this unique study is to compare 2-unit and 3-unit RBBs for the replacement of single missing molar tooth in a randomized clinical trial. These two designs will be clinically evaluated at 6 months , 1 year, 2 years and 3 years to observe the outcome measure

Detailed Summary:
Sponsor: The University of Hong Kong

Current Primary Outcome:

  • Survival of bridges (RBB) [ Time Frame: Three years ]

    Clinically whether the bridge is in subject's mouth. Any complication(s) and associated treatment(s) will be recorded. In case where there is absence of complication/treatment, this bridge is regarded as success.

    If complication occur and/or treatment (apart from routine periodontal maintenance) is required but the original bridge is still in the mouth, this bridge is regarded as survival.

    If lost of the original bridge/abutment tooth (teeth) or complication dedicates the remake of the bridge, the bridge is regarded as failed.

    These will be presented in time to fail (survival) as well as time to complication/treatment (success) by Kaplan Meier curves.

  • Drifting of abutment teeth after insertion of the bridge [ Time Frame: Three years ]

    Models will be taken after insertion/cementation of bridge (RBB) (baseline model) and at review appointments (see Time Frame).

    Vacuum suck down will be made on the baseline model and fitted in subject's mouth during review appointments to screen for any potential tooth movement.

    In potential tooth movement case, models will be scanned and superimposed for analysis of tooth movement (direction and magnitude of movement)



Original Primary Outcome: Same as current

Current Secondary Outcome:

  • Complications [ Time Frame: Three years ]

    Complications related to the abutment teeth / prosthesis (RBB)

    This is measured from review examinations as well as from patient history (any treatment of the RBB by the third parties other than the study centres)

    Review examination will look for: debonding, fracture of framework, fracture of veneer material, caries occurring related to retainer on the abutments, extraction related to periodontal disease or root fracture resulting in loss of the entire reconstruction, abutment endodontic or apical radiolucency, probing depth greater than 5mm

  • Abutment mobility [ Time Frame: Three years ]
    Tested by two handles of mirror (Grade 0, I, II, III) and periotest (Grade 0: -8 to +9; I: 10 to 19; II: 20 to 29; III: 30-50)
  • Proximal contact tightness of the abutments [ Time Frame: Three years ]
    Measured with passing a dental floss and digital tension gauge on metal matrix band
  • Oral Health related Quality of Life [ Time Frame: Three years ]

    Measured by Oral Health Impact Profile 49 (OHIP) and 14-item satisfaction (Visual Analogue Scale VAS)

    OHIP will involve pre-operative (before treatment) as well as peri-operative (after tooth preparation and before RBB cementation) time frame.



Original Secondary Outcome: Same as current

Information By: The University of Hong Kong

Dates:
Date Received: September 4, 2014
Date Started: October 2014
Date Completion: December 2019
Last Updated: October 25, 2016
Last Verified: October 2016