The participants will be informed about the nature and objectives of the study; however,
they will not be informed what desensitizing material they would receive. The study will
be a double blinded (Patient and evaluator) randomized clinical trial with a sample size
of 51, 17 participants for each group (n=17). Bleaching process: A lip and cheek
retractor will be placed. The gingival tissues from the right first molar to the left
first molar will be isolated using a light-cured resin dam to prevent the whitening gel
from coming into contact with the gingival tissue. Participants' lips will be painted
with Vaseline, and protective eyewear will be used. To aid in the isolation process, a
plastic suction tip with high suction power will be used. Opalescence Boost in Office
Whitening Gel, 40% Hydrogen Peroxide bleaching material (Ultradent Products, South
Jordan, UT, USA) will be applied directly on the labial tooth surface from the right
first premolar to the left first premolar. A total of three (20-minute) applications will
be completed in each bleaching session. Participants will undergo 2 bleaching sessions
with one-week interval. Participants will be scheduled for lower arch whitening after 14
days.
Application of the desensitizer: The participants will be assigned randomly to three
study groups. The first group will receive a bio active desensitizer, the second group
will receive a fluoride gel and the third group will receive a placebo gel without a
desensitizer (Table 2). A small amount of the gel assigned for each participant will be
applied directly on the labial surface of each tooth and left undisturbed for three
minutes; care will be taken to cover the entire labial surface, and the gel will be
carried interproximally as much as possible.
Shade evaluation: Teeth shade will be evaluated subjectively and objectively.
Subjectively it will be evaluated using VITA classical shade guide which has 16 tabs
ranging from B1 (lightest value) to C4 (darkest value) by matching the color with the
middle third of the maxillary anterior teeth. One evaluator will record the shade of the
participants' teeth at baseline (before whitening), directly after bleaching, and at days
3, 7, and 14 days follow up periods. Photographs will be taken using a digital camera
immediately after the whitening and at each shade evaluation to document results. Also
teeth shade will be evaluated objectively using VITA easy shade spectrophotometer (VITA
Easyshade V; VITA Zahnfabrik, Bad Säckingen, Germany). The tooth must be well hydrated
before analyzing the tooth color. The shade of the teeth in VITA classical A1-D4 and VITA
3D-MASTER shades will be instantly measured and displayed on the screen. One evaluator
will record the shade of the teeth and the shade will be recorded at baseline,
immediately after bleaching and at 3, 7 and 14 days follow up periods. Sensitivity
Evaluation: Post-bleaching sensitivity will be evaluated by relying on patient's feeling
of pain.
Sensitivity evaluation: All participants will be given a sensitivity sheet to record the
post-whitening sensitivity of the whitened teeth on daily basis up to 14 days according
to the visual analog scale of pain (VAS). The participants will be asked to record the
stimulus that caused sensitivity, including hot, cold, or other. The duration of pain,
whether seconds, minutes, or hours, will be recorded for the 14-day follow-up period.