Statement of the Problem: Demineralization of enamel adjacent to orthodontic appliances frequently occurs, commonly due to insufficient oral hygiene.Purpose: The aim of this study was to compare two microabrasion techniques on improving the white spot lesions as well as subsequent enamel discoloration.Materials and Method: Sixty extracted premolar teeth without caries and hypoplasia were selected for this study. White spot lesions were artificially induced on the buccal surface of each tooth. Teeth were randomly assigned to three treatment groups, each treated with pumice powder as the control, microabrasion with 18% HCl, and microabrasion with 37% H3PO4. Subsequently, the three groups were daily immersed for five minutes in a tea-coffee solution for a period of one week. Colorimetric evaluation was done before and after formation of white spot lesions, after microabrasion, and after immersion in the colored solution; then the color differences (DE) were calculated. Statistical analysis was performed by multiple measurement analysis and the Tukey’s test.Results: This study showed that ΔE between the stages of white spot formation and microabrasion for H3PO4 was more than other groups and for the pumice powder group it was less than the others. Furthermore, there was a significant difference between DE of the three study groups (p= 0.017). Additionally, DE after placing the teeth in the colored solution and microabrasion was the highest for the HCl group and the lowest for the pumice powder group. There was also a significant difference between the three groups (p= 0.000).Conclusion: Pumice powder alone had similar effects as 18% HCl on removing the white spot lesions. Nevertheless, 18% HCl makes the enamel susceptible for subsequent color staining more than the other microabrasion methods.

Background and Aim: Silver diamine fluoride (SDF) is effective for arresting dental caries. However, its application results in dark tooth discoloration, raising concerns among pediatric patients and their parents. This study assessed the effects of potassium iodide (KI) plus hydrogen peroxide (H2O2), H2O2, and Tooth Stain Remover (TSR) on SDF-induced discoloration of artificially demineralized permanent enamel.    Materials and Methods: In this in vitro study, the buccal surface enamel of 33 sound premolars was artificially demineralized and exposed to 38% SDF. The specimens were then randomly assigned to 3 groups of (I) KI + H2O2 (application of water-soluble KI followed by 35% H2O2 on the discolored surface for 3 minutes), (II) H2O2 (application of 35% H2O2 for three 20-minute cycles), and (III) TSR (application of TSR for 3 minutes on the discolored surface). The color parameters were measured at baseline, 1 week after the application of SDF, and 1 week after the application of the abovementioned bleaching agents by a spectrophotometer. Data were analyzed by ANOVA and Tukey test (alpha=0.05).    Results: SDF caused significant color change (ΔE) of demineralized enamel in all groups (ΔE=36-40), with no significant difference among the study groups (P=0.361). Application of all bleaching agents significantly resolved the dark discoloration in all groups, but KI + H2O2 was significantly more effective than H2O2 and TSR (P<0.001). TSR was the least effective (P<0.001). Conclusion: Within the study limitations, the results showed optimal efficacy of KI + H2O2 for correction of 38% SDF-induced discoloration in artificially demineralized permanent enamel.

Background. Acid etching and bonding is a routine process in orthodontic treatment. The present study aimed to evaluate enamel discoloration after using different types of acid etching and adhesive agents. Methods. A total of 105 extracted human premolars were divided into six groups regarding the type of acid etching agent: solution and gel of 37% phosphoric acid, and type of selfcured adhesive agent: Unite (3M, fluoride-free), Resilience (Ortho Technology), and Rely-a-Bond (Reliance, fluoride-releasing adhesive), with each group containing 15 specimens. All the selected teeth were subjected to a staining process, and color parameters were determined using a spectrophotometer. Results. The type of phosphoric acid (solution or gel) had no significant effect on the color change of enamel (P > 0. 05). Resilience significantly changed the enamel color compared to the Unite and Rely-a-Bond (P < 0. 001). There was no significant difference in color change between the Unite and Rely-a-Bond adhesives (P = 0. 67). The difference in color change between all the three time intervals (T0-T1, T1-T2, and T0-T2) was significant (P < 0. 001). Conclusion. In this study, the type of phosphoric acid (solution or gel) did not result in any significant difference in enamel color. Also, considering the lack of the effect of the orthodontic adhesive type in terms of fluoride release or no fluoride release, it can be concluded that this is most affected by the commercial brand of adhesives.

Objectives: The purpose of this investigation was to evaluate the color alteration of dental enamel following the use of light-cured and chemically cured composites for bonding of metal brackets. Materials and Methods: Sixty extracted human premolars divided into five groups (n=12) were included in this study. Metal brackets were bonded using chemically cured (System 1+ and Unite) and light-cured (Transbond XT and Grengloo) composites. The control group remained untreated. After 72 hours of immersion in a staining solution and 24 hours of photoaging, the brackets were debonded, and adhesive remnants were cleaned using a 12-blade tungsten carbide bur and polished with Sof-Lex discs. The color was assessed at the baseline and after cleaning procedures in accordance with the CIE L*a*b (lightness, red/green, blue/yellow) color system. Statistical analyses were performed using paired sample t-test and oneway analysis of variance (ANOVA). Results: The L*, a*, and b* parameters showed a significant increase in all adhesive groups (P<0. 001). The experimental groups showed significant color changes (P<0. 05), and the mean Δ E ranged from 2. 46 to 3. 15 units. No significant difference was found between the Δ E of the adhesive groups (P>0. 05). Conclusion: The enamel color change is influenced by bonding and debonding procedures. Chemically cured and light-cured composites have similar effects on dental enamel color alterations.