Clinical Effects of Dehydration on Tooth Colour
Condition: Color; Change Teeth, Posteruptive
MeSH terms: Dehydration
Study type: Observational

Summary: 
      Dental restorations should mimic sound tooth structures in terms of color and optical
      properties especially in the anterior region. However, closely matching natural teeth with a
      restoration can be one of the most challenging procedure in restorative dentistry. Shade
      matching includes color determination, color communication with dental lab and color
      reproduction with dental restoration for indirect techniques or color determination and
      selection of the appropriate material and application method when using direct techniques.
      Therefore color selection is the first critical step in the restoration procedures and should
      be carried out properly.

      Color determination must be carried out before any of the restorative procedures, isolation
      or impression. Most of the dental procedures cause dehydration and increase the opacity of
      the enamel and teeth appear whiter. Few clinical and in vitro studies evaluated the degree of
      color change after dehydration and rehydration periods. However, inconsistencies exist
      between studies in terms of color change degree and duration of return to appreciable values.

      The aim of the present study was to evaluate the degree of color change in half an hour
      dehydration period of the teeth and to determine if color return to baseline after half an
      hour or 24 hours.

      According to the null hypotheses of the study:

        -  There is no perceptible difference occur after tooth dehydration.

        -  Tooth color will not return to baseline values after half an hour or 24 hours
           rehydration periods.
    

Detailed description: 
      Color measurements Color measurements were performed with a spectrophotometer (SpectroShade
      Micro, MHT Optic Research AG, Niederhasli, Switzerland) by the same experienced dentist in
      the present study. Spectrophotometer was calibrated and used according to manufacturer
      instructions before each set of measurements. All participants were asked for not to mouth
      breath during color measurements. All of the color measurements were carried out under
      standard light conditions with the aim of minimizing the possible inaccurate readings.

      Dehydration procedure Spectrophotometric color measurements were performed at the study
      inception and baseline color parameters were recorded. Lips were retracted by using a lip and
      cheek retractor which placed within 10 s. Upper central and lateral incisors were isolated
      with cotton rolls and air dried for 5 s. Excess saliva was removed with a suction and
      participants keep their mouth half-opened with the help of silicone mouth bite blocks.
      Spectrophotometric measurements were carried out three times during 30 min with 10 min
      intervals during the dehydration period for each test tooth.

      Rehydration procedure At the end of the dehydration procedure, lip retractor and cotton rolls
      were removed and full-mouth rinse with water was done for 30 s. Participants asked to drink a
      bottle of water and close their mouth for 30 min. Participants were asked to return to
      routine daily activity, but not to consume staining beverages such as coffe or red wine.
      Tooth rehydration process was started when test teeth get in contact with saliva.
      Spectrophotometric measurements were carried out at 30 min and 24 h of rehydration.

      CIELAB color parameters (L*,a*,b*) were used to calculate color differences (ΔE) between
      baseline and other measurement periods for each tooth and gingival, middle and incisal thirds
      separetely. Color difference was calculated by using an equation;
      ΔE*=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2. ΔE values were compared to threshold values of
      acceptability(ΔE*=3,7) and perceptibility(ΔE*=1). 11 Color difference and color parameters of
      30 min and 24h dehydration was compared to baseline color parameters.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Participants will be selected amoung patients referring for dental treatments to Tokat
        Gaziosmanpasa University Faculty of Dentistry. Patients in the age range of 18-45 years and
        meeting inclusion criteria will be participated in this study.