Color Match Assessment of a Single Shade Structurally Colored Universal Resin Composite
Condition: Dental Caries (Disorder)
MeSH terms: Dental Caries
Study type: Interventional

Summary: 
      Matching the color of resin composite utilized in anterior teeth is believed to be one of the
      most challenging tasks a dentist has to face in daily practice. The color of the teeth is
      primary influenced by dentin; on the other hand, enamel has a major influence on the color
      perception in terms of lightness. In the layering concept, the missing dental tissues are
      substituted in increments with resin composite of the exact shade as the dental tissue. A
      translucent composite resin is applied over a more opaque composite resin to achieve a depth
      perception similar to that of the natural teeth. Which indicates that the visible color is
      the consequence of diffuse reflectance from the internal dentin or opaque material layer
      through the external translucent layer.

      There are numerous elements that make the color matching problematic. These problems arise
      from the point that color matching rely on many different chromatic properties related to the
      teeth and resin composite; those include hue, chroma and value; translucency, opalescence and
      fluorescence; light diffusion and transmission; and luster and texture of the surface. To
      reach the ideal esthetics, restorative material should mimic the natural tooth in the
      previously mentioned properties, in addition of having a long time color stability.

      Massive efforts were achieved over the years to improve the esthetic properties of dental
      resin composite restorative materials. Recently, a single shade structurally colored
      universal composite (Omnichroma, Tokuyama Dental) intended for use with most direct
      restorative clinical cases was introduced in the market. Its manufacturer claimed that it
      exhibits color change toward the color of the surrounding hard dental tissues. Thus, it has
      the advantages of improving the esthetic appearance of the restoration, decrease dependence
      on shade-matching procedures, decrease the number of shade guide tabs, and counteract for
      color mismatches to some degree.

      Up till now no studies assessed the color match of Omnichroma resin composite in anterior
      teeth cavities clinically. Thus, the aim of this clinical trial was to investigate if the
      single shade structurally colored universal resin composite (OMNICHROMA) will modify its
      shade to match the tooth structure shade in anterior teeth cavities.
    

Detailed description: 
      Participants' recruitment:

      The patients will be selected from outpatient clinic of National Research Centre (NRC),
      Cairo; Egypt Eligible patients who agreed to participate in this trial will sign on written
      informed consents.

      Clinical procedure

        -  Teeth color measurement Each patient first will receive scaling and polishing procedures
           to clean the teeth surfaces. A total of 45 anterior teeth cavities will be prepared.
           Before cavity preparation, shade determination will be performed with Vita Easyshade
           spectrophotometer. The probe tip will be positioned perpendicular and flushed onto the
           buccal surface of the tooth to get correct measurements.

        -  Cavities preparation Appropriate local dental anesthesia (Mepecaine-L) 1mg will be
           injected preoperatively unless declined by the patient. Treated teeth will be properly
           isolated and saliva ejector will be utilized.

      Conservative cavities will be prepared with #330 carbide bur (FG, Dentsply Midwest®) fixed to
      a high speed hand piece with water coolant system. Cavity preparation will be limited to the
      removal of caries and the exact cavity form and size will be obtained after caries removal.
      Each bur will be discarded after 5 preparations.

      A functional esthetic enamel bevel will be prepared using a fine grained finishing diamond
      rotary instrument on the facial surface, the bevel enables harmonious shade transition from
      composite to tooth substance.

      - Application of the adhesive system and resin composite in the prepared cavities Enamel of
      the prepared cavities will be etched using UltraEtch (Ultradent, 40% phosphoric acid) for 30
      seconds. After rinsing with water and air drying, the bonding agent will be applied according
      to the manufacturer's instructions to the cavity using a brush then air-thinned gently and
      light-cured for 20 seconds.

      Omnichroma resin composite will be packed in the prepared cavities using a Teflon coated
      plastic instrument and the restoration will covered with celluloid strip to reduce the oxygen
      inhibition layer and to get a smooth surface, then light-cured for 40 sec. Excess material
      will be removed with scalpel. Finishing and polishing will be performed for the anatomical
      contouring and smoothing of the restorations surfaces using all grates of soflex discs, fine
      and Extra fine diamond burs, medium and fine rubber polishing points.

      Color assessment Color match data will be recorded for the restoration after one week. The
      restorations will be gently dried with cotton and the color values of them will be recorded
      using the Vita Easyshade spectrophotometer.

      The color changes (ΔE) will be calculated from the changes in CIE L, a, and b values (ΔL, Δa,
      Δb) as follows:

      ΔE= [(ΔL)2 + (Δa)2 + (Δb)2]1/2 CIE Lab is expressed by the L coordinate representing color
      luminosity, varying from white to black, a and b coordinates representing the chromaticity of
      the color, with axes varying from green to red and blue to yellow, respectively. The mean of
      the values obtained will be calculated, and the L, a, and b parameters will be determined.

      Visual assessment Visual assessment will be performed by two independent observers with
      normal color vision as checked by Ishiara test. To determine the color-matching between the
      restorations and the teeth. Color-matching visual scoring (VS) values will be expressed
      numerically as follows: 1: mismatch/totally unacceptable, 2: Poor-Match/hardly acceptable, 3:
      Good- Match/acceptable, 4: Close-Match/small-difference, and 5:
      Exact-Match/no-color-difference. All observers will be trained in color-matching and taught
      about the used grading system before the assessment.
    

Intervention name(s): a single shade structurally colored universal resin composite
Intervention type(s): Other
Intervention description(s): Omnichroma is a single shade composite that is claimed to have blending effect with the tooth color, thus eliminate shade matching procedures during restorative treatment
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment