Background and aim: the demand for dental BLEACHING has increased because individual's appearance plays an important role in social relations. The present study aimed to compare the efficacy of an Iranian carbamide peroxide gel (Kimia) with its foreign counterpart (Opalescence PF 15%) used for intracoronal BLEACHING of discolored teeth.Materials and methods: This experimental study was performed on 30 extracted intact central incisors. Root canals were cleaned and shaped with step back technique and were filled with lateral condensation method. Afterwards, gutta percha was removed from 1mm below CEJ and 1mm thick zinc phosphate cement was placed as a liner. Then, the teeth were placed inside 5.25% sodium hypochlorite solution for 24 hours. Whole blood and centrifuge system were used to stain the teeth. Samples were randomly assigned to three groups: 1. Opalescence PF 15% carbamide peroxide 2. Kimia 16% carbamide peroxide 3. Control group (cotton ball impregnated with physiologic serum). Evaluation of the color changes was done once before BLEACHING and once on the seventh day after application of the BLEACHING gel. This evaluation was performed with digital camera and Adobe Photoshop 8.0 software. Data were analyzed by SPSS software and T-test.Results: The BLEACHING value was significantly increased in Kimia group. There was a significant statistical difference between the control group and Kimia and Opalescence PF groups (p=0.001) Moreover, there was a significant difference between Kimia and Opalescence PF groups. (p=0.038).Conclusions: According to the results of the present study, Kimia carbamide peroxide gel is more efficient than Opalescence PF gel in BLEACHING the endodontically treated teeth.

Background and Objective: Tooth whitening has become apopular treatment in esthtic dentistry. The aim of this in vitrostudy was to compare 4 different methods of BLEACHINGincluding home BLEACHING, in-office BLEACHING, combination ofthese techniques and laser on the amount of color change in thenatural teeth. Materials and Methods: A total of 50 intact human premolersteeth of matched size were prepared and divided into 5 groupsof 10 teeth. Group 1: home BLEACHING using 15% carbamideperoxide (CP); Group 2: In-office BLEACHING using 40%hydrogen peroxide; Group 3: combination of first and secondmethods; Group4: 40% hydrogen peroxide combined with 2sections of 30 s of diode laser; Group 5: control (withouttreatment). Tooth color measurements were performedaccording to the CIELab system using spectrophotometerbefore treatment procedure and 1 week after. Results: Comparing the different treatments showed that homeBLEACHING and combination methods were significantly moreeffective (P<0. 05), and the mean total Δ E was 9. 80± 2. 02 and9. 94± 1. 96 respectively. This value for in-office BLEACHINGtreatment was 5. 35± 0. 72. There was no significant difference inΔ E value between laser (4. 14± 1. 82) and control (3. 03± 1. 41)groups by the end of treatment (P>0. 05). Conclusion: The results suggested that the use of diode laser innot a suitable BLEACHING technique and did not improve the colorchanges. In addition, in-office BLEACHING did not provideeffective tooth whitening. However, home BLEACHING andcombination methods are more effective BLEACHING techniques.

Background: As a person ages, the adult teeth often become darker due to changes in the mineral structure of the tooth, as the enamel becomes less porous. Teeth can also become stained by bacterial pigments, foodstuffs and tobacco. Dental BLEACHING was introduced in dentistry in 1877. However, due to modern standards of beauty, this treatment modality has been in great demand and has been the subject of various scientific researches. Therefore, this procedure has undergone many changes. Nevertheless, the action mechanism remains the same, consisting of an oxide reduction reaction with release of active oxygen, free radicals in a solvent (especially water) in which the substance to be bleached donates electrons to the BLEACHING agent, normally hydrogen peroxide. Due to its low molecular weight, the BLEACHING agent penetrates through the porosities of the enamel prisms, reaches the dentin, comes into contact with a large quantity of pigmented organic molecules and breaks them up into shorter and lighter chains that allow the absorption of light in shorter wavelengths. To accelerate this process of oxidation, various sources of energy can be used, such as heat and light. BLEACHING corrects or improves the color of teeth, and is also the least expensive esthetic treatment option. The indications are acquired superficial stains, penetration and absorbed stains, age-related stains, patients who desire conservative treatment to improve appearance, color change related to pulp trauma and necrosis, and interproximal discolorations.Material and methods: A search was performed using the keywords “tooth BLEACHING” and “laser” to identify the current literature on the Tooth BLEACHING with laser. The related articles were searched in databases including IDL, Pub med, Google scholar, and Medline from 2004 to 2010.Results: It is found that selective diode laser radiation can decrease the time of BLEACHING without surface modification. No differences between enamel surfaces were observed.Discussion: Currently, the laser has been proven to be the most valuable energy source for power BLEACHING with simple and short application in the office.

Statement of Problem: BLEACHING materials are able to change the surface morphology as well as mineral and organic content of tooth structure. Considering that BLEACHING is done for aesthetic purpose, awareness of the possible effect of these materials on hard tissue is important, because it may affect the restorative treatments.Purpose: The aim of this study was comparing the effect of two BLEACHING materials, Kimia and Ultradent both containing 35% H2O2, on tooth enamel by SEM. Materials and Methods: Five intact central incisors were cut into three sections vertically and each part was randomly divided into three groups. Group 1 (control), without any BLEACHING. Group 2, bleached with Kimia 35% H2O2. Group 3, bleached with Ultradent 35% H2O2. Each tooth served as its own control. Then the samples were observed by SEM with 250 and 500 magnifications.Results: In the control group some scratches and small white grains were observed which seems to be the result of mastication trauma and pumice powder. In the other groups, morphologic changes like increased surface roughness, deepening of cracks, rod exposure and presence of new cracks were observed. The two experimental materials did not differ in these regards.Conclusion: It seems that both studied materials have limited destructive effects on tooth enamel which seems to be of no clinical importance.

Background and Aim: Diagnosis of dental caries with Diagnodent device has been found to be comparable to visual and radiographic diagnostic methods. The aim of this study was to determine the effect of Aging, Staining, and BLEACHING on Diagnodent readings in composite resin restorations.Materials and Methods: This was an experimental in vitro study in which 108 disk-shaped specimens were fabricated from 6 different composite resins including: 3 M p60, Kerr point 4, Vivadent Heliomolar, Ultradent flow, Tetric flow and Kerr flow. The samples were divided into 3 groups. Group 1was aged in water, group 2 was stained with tea and group 3 was bleached with 16% Carbamide peroxide. Specimen Fluorescence was measured with Diagnodent (Kavo- U.S) before and after these treatments. Data were analyzed using mixed repeated Measure Model ANOVA.Results: This study was performed on 108 composite resin specimens. All samples aged in water showed higher reading values; only Tetric flow exhibited a lower mean value (P<0.001). All samples stained with tea showed higher readings(P<0.001) and all materials bleached with 16% Carbamide peroxide were reported to have lower values; only Kerr flow exhibited a higher mean value than basic situation.Conclusion: The results indicate that aging and staining can result in an increase in the Diagnodent readings of the composite resin restorations while BLEACHING lead to a decreased the readings. However, the reported differences in Diagnodent readings were not significant enough to result in a false positive diagnosis of caries.

Background: Reports indicate that lasers accelerate tooth BLEACHING by activating BLEACHING agents. Due to the lack of sufficient information about the application of the Er, Cr: YSGG laser, the present study was conducted to compare the degree of enamel color changes after teeth BLEACHING treatment using chemical whitening agents alone and with Er, Cr: YSGG laser. Methods: In this laboratory study, several human molars were cut into 4 parts after cutting and removing the pulp. Based on laser application, the samples were randomly divided into two groups (N = 20), including the chemical BLEACHING group (G1) and the chemical BLEACHING group with activated laser (G2). In G1, the BLEACHING process was performed only with 35% hydrogen peroxide for two weeks (3 times, 15 minutes each week). In G2, the gel BLEACHING was activated by the Er, Cr: YSGG laser with a wavelength of 2780 nm. It was placed 2. 5 cm from the sample surface with BLEACHING agents and applied twice for 15 seconds. Color changes were recorded using a spectrophotometer before BLEACHING, immediately after, 1 month, and 3 months after BLEACHING. Data were analyzed by SPSS software (version 18), Repeated measures ANOVA, and Tukey’, s tests (α,= 0. 05). Results: Mean and standard deviation of changes in Δ, a showed a significant difference between the gel group and the gel group with laser over time (P < 0. 05), but this difference was not observed in Δ, L and Δ, B (P > 0. 05). However, the intragroup comparison demonstrated significant changes in Δ, a and Δ, b in both groups over time, but not in Δ, L (P > 0. 05). The Δ, E changes in both the laser and BLEACHING gel groups were above the threshold of 3. 3. The results indicated no significant difference between G1 and G2 in terms of the Δ, E (P > 0. 05). Finally, the results revealed that 1 and 3 months after teeth whitening, Δ, E changes in both groups were greater than 3. 3. Conclusions: Overall, the application of the Er, Cr: YSGG laser had no positive effect on BLEACHING efficacy when using a 35% hydrogen peroxide gel. Based on the findings, color changes were stable in the studied groups for up to 3 months after teeth BLEACHING.

Background: Evidence on the protecting effect of laser on bleached enamel is scarce and controversial. Therefore, we aimed to test for the first time whether different wavelengths of diode laser (810 and 980 nm) can prevent enamel surface corrosion. We also tested for the first time whether such therapeutic effects of laser are limited to specific “ laser‑ activated” BLEACHING gels or both conventional and laser‑ activated gels. Materials and Methods: In this qualitative experimental study, ten intact human teeth were randomly assigned to five Groups. They were sectioned into twenty buccal/lingual pieces. The groups were: (1) laser‑ activated gel + 810 nm laser, (2) laser‑ activated gel + 980 nm laser, (3) conventional gel + 810 nm laser, (4) conventional gel + 980 nm laser, (5) conventional gel only, and (6) laser‑ activated gel ‑ no irradiation. Buccal sections in each group were subjected to BLEACHING (according to the stated protocols), and later subjected to field‑ emission scanning electron microscopy (SEM) and X‑ ray diffraction (XRD). The lingual pieces were used as “ before‑ treatment” negative controls for XRD. Results: XRD showed an increase in the mineral phase and crystallinity of the enamel in all BLEACHING groups. This was stronger in the laser‑ irradiated groups with conventional BLEACHING agent. SEM showed a complete etched surface in the positive control groups (i. e., bleached using conventional agent). However, all four laser groups had almost intact surfaces. Conclusion: This study showed the positive effect of diode laser irradiation at 810 nm or 980 nm wavelengths on the prevention of BLEACHING damage, irrespective of the activation mechanism of the BLEACHING gel in use.