Nobio Clinical Study - Demineralization Prevention With a New Antibacterial Restorative Composite
Condition: Dental Caries; Denture, Partial, Removable
MeSH terms: Dental Caries
Study type: Interventional

Summary: 
      Nobio has developed dental restorative materials with long term antibacterial properties in
      order to fight recurrent decay/caries around restorations. These composites with incorporated
      non-leaching antibacterial agents might overcome the vicious circle of newly developed
      cavities around freshly placed fillings.

      The investigators will ask lower partial denture wearers to allow them to place a "gap model"
      with the Nobio-composite and enamel slab in one denture flange. In the other denture flange a
      gap model with a standard composite will be placed as control. In the laboratory the
      investigators will test with established methods for demineralization/caries prevention in
      the test and control enamel slabs, respectively.
    

Detailed description: 
      As a major issue in dentistry, it has been stated that two-thirds of all restorative
      dentistry involves the replacement of failed restorations. Secondary caries indicates a
      lesion developing at the margins of an existing restoration and is the major reason for
      replacement of amalgam and composite resin restorations in operative dentistry.

      In research the use of experimental intra-oral caries models dealing with caries prevention
      has increased. The most realistic experimental model is the in vivo model that uses living
      teeth, followed by the in situ model using specimens with natural surfaces held in the mouth
      during the experimental period. In situ models have the potential to study both fundamental
      aspects of the caries process as well as more applied research problems in caries prevention
      in human subjects without actually causing caries in the natural dentition.

      To simulate a failed interface between a tooth and a restoration, a gap can be formed between
      an enamel slab and the restoration prior to a cariogenic challenge. The "gap-model" will be
      inserted for instance into the denture flanges, and the cariogenic challenge occurs inside
      the mouth during the wear period..

      Nobio has developed dental restorative materials with long term antibacterial properties in
      order to fight recurrent decay around restorations. These composites with incorporated
      non-leaching antibacterial agents might overcome the vicious circle of newly developed
      cavities around freshly placed fillings. The ongoing caries activity due to bacteria around
      the filling may be interrupted by quaternary ammonium silica dioxide (QASi) particles
      incorporated in the test composite at 1.2% (by weight). These particles are members of the
      Nobio Antimicrobial Particle (NAP) family (Nobio, Israel). QASi are synthesized to form a
      high concentration of antimicrobial groups that are covalently-bound onto a carrier core,
      such as silica. The resulting micro or nano-sized QASi particles are mixed with other fillers
      of the dental composite material, during manufacturing. Following in situ placement and
      light-initiated polymerization, QASi particles are permanently retained in the final dental
      restoration. Laboratory studies have shown that the quaternary ammonium silica particles are
      potent antibacterial agents, do not leach out in contrast to other antimicrobials or caries
      preventive active substances, inhibit the breakdown of the composite, and maintain
      antibacterial activity over time.

      The study is an in situ study. Subjects, wearing lower partial dentures with acrylic flanges
      on both sides of the mouth will be recruited. On each side of the denture an enamel slab will
      be placed next to a composite, separated by a tiny gap. On one side of the denture the
      composite will be Nobio's antibacterial composite, on the other side a regular composite (a
      Nobio composite w/o particles or another commercial composite will serve as control material.
      Enamel slab and composite will be recessed into the flange, allowing microbial plaque to
      accumulate on top of it and especially in the gap.

      After wearing the dentures for four weeks with the slabs, decalcification - ΔZ mineral loss -
      in the enamel slabs adjacent to the gap will be determined by cross-section microhardness
      testing in the laboratory. Average ΔZ mineral loss will be calculated for the Nobio group and
      the control group, and difference will be tested for statistical significance.
    

Intervention name(s): Nobio composite; traditional composite
Intervention type(s): Device; Device
Intervention description(s): Nobio has developed a bactericidal composite, which does not leak out the bactericidal nano fillers; traditional composite which has no bactericidal activities
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: In-situ testing using a gap model inside the two flanges of a removable partial denture
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Prevention
Keywords: composite bactericidal; caries prevention