Dissertation
Effect of tooth whitening and remineralizing agents on surface and color changes of dental hard tissues
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2021
DOI: 10.17077/etd.006296
Abstract
Objectives: To evaluate the effect of different tooth whitening agents on the erosion depth of enamel and dentin, and to evaluate the effect of application protocols involving two remineralizing agents on the surface roughness, microhardness and color change of bleached enamel. Methods: Specimens were prepared from sound extracted human molars. To evaluate the erosion depth, enamel and dentin blocks were randomly assigned to different bleaching agents treatment groups. Erosion depth was evaluated following treatment using polarized light microscope. To evaluate the effect of the application protocol of remineralizing agents (sodium fluoride and casein phosphopeptide-amorphous calcium phosphate) on surface roughness, microhardness and color change, specimens were randomly assigned to different treatment groups where each of two remineralizing agents were applied before, after or before-and-after bleaching. Measurements were compared between baseline and post-treatment. Surface roughness was assessed using a 3D profilometer. Microhardness was assessed using a Knoop microhardness device. Color measurements were evaluated instrumentally using a spectrophotometer based on the CIE LAB system. Visual color assessment was evaluated using a shade guide. Nonparametric statistical procedures were used to compare treatment groups with appropriate adjustment for multiple comparisons, specifying an overall significance level of 5%.
Results: Different tooth whitening agents produced various degrees of dental erosion of enamel and dentin. The depth of the erosion caused by tooth whitening agents varied depending on the agent used. Surface roughness evaluation showed that all treatment groups had significantly lower surface roughness change (ΔRa) when compared with the bleaching alone, and higher ΔRa when compared with the negative control group. Knoop Microhardness evaluation showed that all treatment groups had significantly lower change in microhardness when compared with the bleaching alone, and higher change in microhardness when compared with the negative control group except in one instance; there was no difference in the microhardness change between the group treated with sodium fluoride before bleaching when compared to the group treated with bleaching only. In terms of color assessment, all treatment groups showed significantly higher values of L* and lower values of b* and a* when compared to the negative control group. Based on the visual assessment of color change, all treated groups showed significantly more improvement in shade guide units than the negative control group.
Conclusion: Within the limitations of this study, results show that some tooth whitening agents can produce various degrees of erosion of enamel and dentin. The application of sodium fluoride or casein phosphopeptide-amorphous calcium phosphate before, after or before-and-after bleaching produced various degrees of protection against the increase of surface roughness, decrease of microhardness of enamel without affecting the efficacy of the tooth-whitening treatment.
Details
- Title: Subtitle
- Effect of tooth whitening and remineralizing agents on surface and color changes of dental hard tissues
- Creators
- Rawa A. Alammari
- Contributors
- Deborah Dawson (Advisor)SoRan Kwon (Committee Member)Jeffrey Banas (Committee Member)Philip Wertz (Committee Member)Justine Kolker (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Oral Science
- Date degree season
- Autumn 2021
- DOI
- 10.17077/etd.006296
- Publisher
- University of Iowa
- Number of pages
- xviii, 240 pages
- Copyright
- Copyright 2021 Rawa Alammari
- Language
- English
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 220-240).
- Public Abstract (ETD)
Tooth bleaching is a cost-effective method to improve the smile appearance. Some of the reported drawbacks of tooth whitening treatment include sensitivity, and gingival irritation. Additionally, some reports raised concerns regarding the potential surface changes of tooth surface. The use of protective agents can help alleviate the tooth-whitening induced sensitivity and protect against the potential surface changes. However, there is no established protocol for the use of these protective agents with the whitening treatment.
The purpose of this study was to evaluate the effect of different whitening treatments on the loss of tooth enamel and dentin. Additionally, this study evaluated the effect of different application protocols involving two protective agents including sodium fluoride and a calcium-phosphate paste consisting of casein phosphopeptide-amorphous calcium phosphate on surface changes of tooth enamel. Since color change is the most important outcome of tooth-whitening it was crucial to assess the effect of the application protocols of the protective agents on the efficacy of the whitening treatment.
Extracted human molars were used to prepare the specimens for the experiments. Different tooth whitening treatments were applied to enamel and dentin, the damage to the surface was assessed following treatments. The results showed various degrees of surface damage ranging from none to moderate. Further, to assess the protective effect of different application protocols of the two protective agents, the agents were applied either before, after or before-and-after the whitening treatment. Surface changes were assessed in terms of surface roughness and hardness before and after treatments. The results showed that all the application protocols of the protective agents produced various degrees of protection against surface changes of enamel when used in conjunction with the whitening treatment. The results of the color evaluation showed the use of protective agents with tooth-whitening did not affect the color changing effect associated with the treatment.
In conclusion, within the limitation of the study, some tooth-whitening treatments have the potential to produce surface changes of enamel and therefore should be used in moderation under the dentist’s supervision. The use of protective agents in conjunction with the whitening treatment provides protection against potential surface changes without affecting the efficacy.
- Academic Unit
- Oral Pathology, Radiology and Medicine
- Record Identifier
- 9984210642402771
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