Potassium Nitrate and Post-bleaching Sensitivity
Condition: Medicaments Substances in Therapeutic Use
MeSH terms: Hypersensitivity
Study type: Interventional

Summary: 
      This study will determine the effectiveness of the use of desensitivity gels prior in office
      bleaching on risk and intensity of tooth sensitivity caused by in-office bleaching using 35%
      hydrogen peroxide and using different types of potassium nitrate. Materials and Methods:
      Seventy five patients will be selected for this triple-blind, randomized, cross-over,
      placebo-controlled clinical trial. 10 minutes prior to bleaching procedure, patients will
      receive the the potassium nitrate 2% or placebo gel application on vestibular surface and
      Toothpaste 15 days before start the bleaching procedure (group 1: placebo gel + Colgate
      toothpaste; Group 2: Placebo gel + Nitrate toothpaste Sensodyne and Group 3: Potassium
      Nitrate + Colgate toothpaste). The whitening treatment with 35% hydrogen peroxide will be
      carried out in two sessions with a 7-day interval.

      Tooth sensitivity will be assessed before, during and 24 hours after the procedure using
      analog visual and verbal scales. Color alteration will be assessed by a Vita Guide scale at
      the end of the last session. Relative risk to sensitivity will be calculated and adjusted by
      session; while comparison of overall risk will performed by McNemar's test. Data on the
      sensitivity level and color shade will be subjected to the Friedman, Wilcoxon (α = 0.05). If
      necessary, multiple comparation will be done using Tukey's test.
    

Detailed description: 
      This study will be a randomized, triple-blinded, placebo-controlled clinical trial, and split
      mouth study design.

      The patients included will be submitted to two in-office bleaching sessions receiving the
      potassium nitrate 5% or placebo gel (prior the bleaching session, for 10 minutes), associated
      to normal toothpaste or potassium nitrate containing toothpaste (15 days prior and during the
      bleaching procedure).

      A delay of 1 week between the sessions will be established.

      Participants:

      Patients included in this clinical trial will be between 18 and 29 years old with good oral
      health, all anterior tooth healthy and to agree with TCLE (Term of Free and Informed
      Consent). Only patients presenting all six upper anterior teeth with shade mismatching with
      2.5 M2 (VitaClassicalscale, Vita-Zahnfabrik, Bad Sackingen, Germany).

      Patients with any of the six upper anterior teeth with caries, restoration, severe
      discoloration (e.g., stains caused by tetracycline), enamel hypoplasia, gingival recession,
      dentin exposure, pulpitis, or endodontics will be excluded. Participants submitted to
      previous bleaching procedures, presenting prior tooth sensitivity, known allergy to any
      component of medication used in the study, pregnant or breastfeeding, lack the tretament will
      be also excluded.

      Sample Size Calculation:

      The sample calculation will be based on the primary binary outcome (sensitivity risk 24 hours
      after the procedure) for superiority trial. Power of the test will be set at 80%, considering
      a type I error of 0.05; risk to tooth sensitivity for control and experimental group of 25,2%
      with reduction of 60%. The calculation resulted in 75 patients.

      Randomization:

      A randomized list will be computer-generated by a person not involved in intervention or
      evaluation. The participants were defined as blocks in the randomization process, where the
      sequence of treatment (placebo or etodolac) will be randomly set for each block by using
      computer-generated tables (www.sealedenvelope.com). The sequence will be inserted into sealed
      envelopes numbered from 1 to 75 that were opened by the operator only at the moment of the
      intervention. The patients were numbered according to the sequence of enrollment. Neither the
      participant nor the operator will know the group allocation determining blinding to the
      protocol.

      Baseline evaluation:

      Prior to bleaching procedure, the teeth will be cleaned using rubber cups associated to
      pumice and water. The shades of six upper anterior teeth will be assessed on a baseline using
      the Vita classical guide scale.

      Intervention:

      Prior to each bleaching session, the patients will receive the potassium nitrate 2% or
      placebo Gel for 10 minutes. Also, Normal and potassium nitrate toothpaste will be used before
      and during the bleaching tretament, as follows: group 1: placebo gel + Colgate toothpaste;
      Group 2: Placebo gel + Nitrate toothpaste Sensodyne and Group 3: Potassium Nitrate + Colgate
      toothpaste.

      Neither the operators responsible for intervention and evaluation nor the patients knew the
      content which treatment will be done.

      A light-cured resin dam will be applied on the gingival tissue corresponding to the teeth to
      be bleached.

      A 35% hydrogen peroxide based bleaching agent (DFL) will be mixed and applied on the
      vestibular surface of teeth, remaining for 40 minutes. After this time, the bleaching agent
      will be removed. A second session will be carried out after 1 week following the same
      procedures.

      Evaluations:

      The tooth sensitivity reported by patients will be assessed using a visual analog scale (VAS)
      and verbal rating scale (VRS). The VAS consisted of a scale 10 cm in length ranging from
      green (absence of pain) to red (unsupportable pain). The patient set his or her level of
      sensitivity by pointing to the color corresponding to this level, while the distance from
      this point to the green border will be recorded. For VRS, the patient reported his or her
      level of sensitivity based on scores: 0 = none, 1 = light, 2 = moderate, 3 = considerable and
      4 = severe. The tooth sensitivity will be assessed during the bleaching, immediately after
      bleaching agent removal and after 24 hours. For this last assessment, only the VRS will be
      used. Tooth sensitivity will be measure: baseline, at 40 minutes during the bleaching
      procedure, after the bleaching procedure and 24 hours after. One week after each session the
      tooth color will be evaluated again using the same procedure described previously.
    

Intervention name(s): Placebo gel + Normal Toothpaste; Placebo Gel + Potassium Nitrate Toothpaste; Potassium Nitrate Gel + Normal Toothpaste
Intervention type(s): Other; Other; Other
Intervention description(s): 15 days before and during the period of bleaching sessions: Tooth paste used will be normal (Colgate).
Teeth will be cleaned using rubber cups associated to pumice and water;
Relative isolation with roller cotton will be done;
Prior to each bleaching session, the patients will receive the placebo gel application on vestibular surface, for 10 minutes.
Gingival dam will be performed using a fluid resin.
A 35% hydrogen peroxide based bleaching agent will applied on the vestibular surface of teeth, remaining for 40 minutes.; 15 days before and during the period of bleaching sessions: Tooth paste used will be normal tooth paste (Colgate).
Teeth will be cleaned using rubber cups associated to pumice and water;
Relative isolation with roller cotton will be done;
Prior to each bleaching session, the patients will receive the 5% Potassium Nitrate gel application on vestibular surface, for 10 minutes.
Gingival dam will be performed using a fluid resin.
A 35% hydrogen peroxide based bleaching agent will applied on the vestibular surface of teeth, remaining for 40 minutes.; 15 days before and during the period of bleaching sessions: Tooth paste used will be Potassium Nitrate containing (Sensodyne).
Teeth will be cleaned using rubber cups associated to pumice and water;
Relative isolation with roller cotton will be done;
Prior to each bleaching session, the patients will receive the placebo gel application on vestibular surface, for 10 minutes.
Gingival dam will be performed using a fluid resin.
A 35% hydrogen peroxide based bleaching agent will applied on the vestibular surface of teeth, remaining for 40 minutes.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment