A COMPARATIVE STUDY OF THE EFFICACY OF BLEACHING
TRAYS FABRICATED WITH AND WITHOUT RESEVOIRS
Submitted in partial fulfillment of the requirements for the
Baccalaureate Degree in Dental Hygiene
Laura I. M. Green
We hereby recommend that the thesis prepared under our supervision by Laura I. M. Green be accepted as fulfilling partial requirements for the baccalaureate thesis in Dental Hygiene.
Department Chair Date
The purpose of this research was to evaluate the impact that bleaching tray reservoirs had on the efficacy of tooth bleaching. It was hypothesized that the use of reservoirs in bleach tray fabrication would affect the bleaching process, thus increasing the tooth shade of research participants. The research design used was convenience sample, one group pretest – posttest. Research participants were given a bleach tray with reservoirs with block-out on only one side of the mouth. This created a built-in control for each patient. The results revealed that the use of reservoirs did not improve or impair the bleaching agent. On both the pre- and post-treatment evaluation of tooth shades, the quadrants that had reservoirs with block-out and those that did not were essentially the same. Therefore, while the participants may have had an increase in the shade guide units (SGUs), the fact that reservoirs were used on one side of the mouth did not show a significant change from left to right.
In the era of extreme makeovers, image and beauty has taken center stage in the arena of social acceptance. Seeing that, hoards of people have flocked to any establishment that professes to embellish their appearance. One of these types of establishments is the local dental office. Dentists are offering everything from superficial cosmetic dentistry to full mouth reconstruction. Bleaching is the most effective, affordable and least invasive of procedures that can quickly change a person’s physical appearance. Bleaching of vital teeth has become a recognized treatment for people seeking acceptance and a
The delivery of the bleaching agent has also evolved over the years. There have been many variations of bleach delivery including: in-office treatments, toothpastes, dentist directed self-applied treatments and bleach impregnated plastic strips. With all of the bleaching options available determining the best for each individual can be difficult for the consumer and dentist alike if they are unaware of the research.
The bleach trays that are most commonly offered at the dental office consist of a soft plastic that is form fit for each individual patient. There is some uncertainty about whether these trays require a reservoir to hold the bleach. The objective of this study is to compare the effectiveness of the at-home dental bleaching trays with and without reservoirs for whitening natural teeth. The review of literature revealed the definition and processes of bleaching, the effects of bleaching on oral soft tissue and the methods that make this process more efficacious.
Definitions and Processes
The active ingredient in dental bleaching is hydrogen peroxide. It is commonly delivered in the form of carbamide peroxide, which is a combination of hydrogen peroxide and urea. The urea is present to help stabilize the hydrogen peroxide (CRA, 1997). Bleaching of the tooth structure occurs when the solution begins to oxidize while in contact with the tooth. “Carbamide peroxide breaks down into urea and hydrogen peroxide, with the latter then breaking down into free radical, which eventually combine to form molecular oxygen and water” (Gökay et al, 2000, p. 430). All of the studies cited indicated there is a risk of tooth hypersensitivity and gingival irritation.
Effects of Bleaching
Resent studies have looked at many effects of bleaching on oral structures. Some of these include effects on enamel, gingival tissues and pulp chambers. An extensive application time (several hours to overnight) raises concerns of hazards such as toxicity and tissue damage caused by peroxide-containing products.
Oltu and Gürgan (2000) studied the effects of three concentrations of carbamide peroxide (10, 16 and 35%) on the structure of enamel in vitro. Using both infrared spectroscopy analysis and X-ray diffraction analysis they found that both 10 and 16% had only small deviations in the enamel structure. These same tests suggested that the use of 35% would “imply changes in inorganic composition,” (p. 333). However, the cause of this change is not clear. They go on to state the need for a “conditioning pre-rinse to accelerate the effect of the gel” may have caused the variations in the enamel, (p. 338).
As to the effects on gingival health it is a well known fact that the most common side effects of bleaching teeth are tooth sensitivity and gingival sensitivity. However,
The effect of bleaching agents is also a concern for the health of the tooth’s pulp. Gökay, et al(2000) studied the penetration of the pulp chamber by carbamide peroxide bleaching agents on teeth restored with a composite resin. This goes to the cause of tooth sensitivity following beaching. It was found that those teeth with composite restorations allow a higher amount of the peroxide agent to reach the pulp of the tooth. The study does state “it is not clear at what concentration of hydrogen peroxide does irreversible pulpal damage occur” (p. 430).
Methods that Improve Bleaching Process
It was proposed by the dental product company Ultradent® that reservoirs in the vacuum formed bleaching trays would a benefit to the bleaching process. Clinical Research Associates (CRA, 1997) reports, “Reservoirs built into trays [are used] to increase active ingredient available for bleaching,” ( p. 1). This reservoir is situated in the tray by placing LC Block-Out Resin directly on the patient’s dental models. After the resin is placed the bleach trays are then prepared in the usual manner. Wille, et al. (2000) state, “it is desirable that a tooth-bleaching agent remain in contact with the enamel, and should not flow or be displaced with resulting contact with soft tissues,” ( p. 1061). The reservoirs created by block-out may be beneficial in keeping the carbamide peroxide from flowing onto the soft oral tissues. Carboxypolymethlene polyer may also add to the adherence of the bleach agent to the teeth, (Wille, et al).
METHODS AND MATERIALS
This study used a convenience sample of dental office patients that wanted to bleach their teeth. The dental office was located in Midvale,
Figure 1: Representation of Reservoir Block-Out
instruction and written directions on proper use of the bleaching product and care of the trays and a pre-bleaching shade were determined. The product used was Day White Excel 3 by Discus Dental with 7.5% carbamide peroxide. The product was to be placed in the trays and remain on the teeth for 30 minutes twice a day for approximately two weeks (see Figure 2 for representation of bleaching tray with reservoirs on model). The dental team at the dental office completed the data collection (see Appendix B).
Figure 2: Prepared Bleaching Tray with Resevoir as seen on Model
On the return visit a post treatment shade was recorded as well as a brief interview to confirm how often the bleaching was preformed and whether the patient
Figure 3: Vita Shade Guide
Table 1: Shade Guide Units (SGU) Formula (Heymann, 1998)
experienced any sensitivity – soft or hard tissue. The degree of improvement in tooth shade was evaluated according to the Vita Shade Guide and the shade guide unit (SGU) change formula pictured in Figure 1 and Table 1 (Heymann, 1998).
Further defined, this meant that a participant that had pre-treatment shade of A4 and a post-treatment shade of A3 had a total SGU of 6 units, because they began at 15 and ended at 9. These SGU numbers will be averaged and compared to determine the degree of shade change pre- and post-treatment.
The purpose of this research was to evaluate the impact that bleaching tray reservoirs had on the efficacy of tooth bleaching. It was hypothesized that the use of reservoirs in bleach tray fabrication would affect the bleaching process, thus increasing the tooth shade of research participants. The results revealed that the use of reservoirs did not improve or impair the bleaching agent. On both the pre- and post-treatment evaluation of tooth shades, the quadrants that had reservoirs with block-out and those that did not were essentially the same. Therefore, while the participants may have had an increase in the SGUs, the fact that reservoirs were used on one side of the mouth did not show a significant change from left to right.
The research design used was a one group pretest – posttest design (T X T). The pre- and post-treatment shades were listed and an SGU number was assessed as an indicator of change in tooth color (Table 3). The result revealed that the statistical
Table 2: Raw Data in SGUs (N=13)
mean for SGUs was 4.92, the median was 4 and the mode was 4 and 6 (refer to Table 2 & Figure 4). Although there were 12 research participants, the final tally in SGUs resulted in 13 scores because one participant’s teeth demonstrated two shades on the Vita shade guide.
Table 3: Matrix of Participant Pre- and Post-Treatment Tooth Shades
Figure 4: Graph of SGU Mode
There was a slight attrition rate in the research population in that 2 participants were dropped due to non-eligibility and non-compliance issues.
The following are pictures of three participants that had a shade guide change and are included for clarity of what the researcher was looking for (refer to Table 4 on the next page).
Table 4: Visuals of Shade Change on Research Participants
The patient’s were polled on the frequency of use of the bleaching product. The mean (N=12) was 6.17 applications. In addition, 2 of the 12 participants experienced gingival irritation due to contact with the carbamide peroxide. This situation was resolved with the alteration of the bleaching tray.
The purpose of this research was to evaluate the impact that bleaching tray reservoirs had on the efficacy of tooth bleaching. It was hypothesized that the use of reservoirs in bleach tray fabrication would affect the bleaching process, thus increasing the tooth shade of research participants. The research design used was a one group pretest – posttest design (T X T). The results revealed that the use of reservoirs did not improve or impair the bleaching agent.
An identified flaw in the research was that all of the products (bleach, block-out etc) should have been manufactured by the company, Ultradent, which has made the claim in support of reservoirs. In addition, there should have been improved calibration among data collectors; thus, limiting the threat to the validity of the shade scores given.
The results of this study did not support the claim by Ultradent that reservoirs are necessary for improved bleaching efficacy. This result impacts dental hygiene in that the cost and time incurred in preparing bleaching models with reservoirs is unnecessary and would not need to be recommended.
Suggestions for future research would be to investigate if reservoirs impact the rheological characteristics of tooth bleaching materials. Further stated, would the use of reservoirs impact the degree of soft-tissue irritation due to excessive exposure to bleaching agent?
Clinical Research Associates. (1997). Major changes in home bleaching over past 8 years. CRA Newsletter, 21:4.
Heymann, H. O, et al.(1998). Clinical evaluation of two carbamide peroxide tooth-whitening agents. Compendium, 19, 359-374.
Niderman, R., et al.(2000). Effectiveness of dentist-prescribed, home-applied tooth whitening, a meta-analysis. The Journal of Contemporary Dental Practice 1:1-16. Retrieved on
Oltu, Ü, & Gürgan, S. (2000). Effects of three concentrations of carbamide peroxide on the structure of enamel. Journal of Oral Rehabilitation. ;27:332-340.
Willie, T., Combe, E. C., Pesun,
Informed Consent for Participation in Dental Bleaching Study
This study includes research of the effects of dental bleaching with and without reservoirs in an at-home bleach tray. This is to determine which method of at-home bleaching tray is more effective. This study will take 2-3 weeks per participant depending on the pre-treatment tooth shade and the participants desired post treatment tooth shade. This treatment will require at least three visits to the dental office. Each individual will have dental impressions taken of the upper and lower teeth and this and the standard dental bleaching consent forms will be signed by the participant. On the first return visit at-home bleach trays and bleaching product will be delivered along with instructions of how to use the product. At this time the pretreatment shade will be recorded. On the last visit a post treatment shade will be recorded and the need for further bleaching will be
The foreseeable risks or discomforts to participants are no different than with any other dental bleaching procedures, (see the attached standard dental bleaching consent form).
There is not more than a minimal risk to participants. There may be a risk of the tooth shades being different on the left and right sides of the mouth, which is dependent on the effectiveness of the bleach in the different types of at-home bleach trays. If this difference of shade occurs the participant will be presented, at no cost to them, a new at-home bleach tray and additional bleach to balance the shade.
The benefit to the participant is whiter teeth.
An alternative procedure to at-home bleaching is in-office bleaching. The time involved is shorter, but the cost is higher.
The identity of each participant will be held confidential in all records of this study. There is a possibility that the Food and Drug Administration may inspect the records of this study.
There is no additional cost beyond the standard fee charged by the dental office of Dr. Stephen O. Wright DDS to participate in this study.
For answers to questions about this research and the participants rights please contact:
Laura Green (801) 897-9338
Participation in this study is completely voluntary. There will be no penalty to participants that chose to discontinue their participation. Participants may withdraw from the study at anytime.
Data Collection Form
Informed Consent signed___________________________________
Instructions and Brochure delivered__________________________
Pre-bleaching shade_____________ Date _____________ Collectors Initial__________
Reservoir - Left or Right
# of bleach treatments______________________________________
Report of sensitivity_______________________________________________________
- Title: Dental Bleaching Trays With And Without Reservoirs: A Comparative Study.
- Description of the study: This study will compare the effectiveness of at-home dental bleach trays with and without reservoirs. Bleach trays will be fabricated with reservoirs on the left or the right and no reservoirs on the opposite side.
- Duration of the study: The study will span 5 months.
- Multicenter study: The study will include one center – The private office of Dr. Stephen O. Wright, DDS in Midvale,
- Number of subjects: There will be 12 subjects.
- Health status of the subjects: The subjects should be in good health as determined by the dentist in reviewing a current health history.
- Subject groups excluded: Subjects with teeth lighter than a B-2 on the Vita shade guide will be excluded.
- Ages of subjects: The age of the subjects will be 18 years and older.
- Design of the study: Participants will be seen in Dr. Stephen O. Wright’s Midvale, UT dental office. Each patient will serve as their own control with one side of the mouth using a reservoir tray design and the other side of the mouth using a non-reservoir tray design. A 7.5% carbamide peroxide bleaching solution will be used for the treatment. The Vita shade guide will be used for pre and post-treatment shades. The shades will be compared pre and post-treatment within the tray design group and subsequently the two groups will be compared.
- Risk to subjects: The risk to subjects is minimal as this is a non-invasive procedure that is employed routinely in the dental setting. There may be a risk of the tooth shades being different on the left and right sides of the mouth.
- Benefits to subjects and others: The benefit to the subject is whiter teeth. The benefit to others is the awareness of the most effective whitening treatment.
- Costs to be borne by subjects: There is no additional cost in addition to the standard fee charged by the dental office of Dr. Stephen O. Wright, DDS.
- Is confidentiality assured: Subjects will be recruited at the time they seek whitening treatment at Dr. Stephen O. Wright’s dental office. The procedure of whitening and the procedure of the study will be explained verbally as well as sign an informed consent for both whitening and the study. Once the informed consent is signed the subject will receive an identifying number to ensure the confidentiality of all personal information.
- Contract or grant number: __________NA_____________, Weber State University Dental Hygiene Department.
- Name of principal investigator and department:
Investigators: Laura I. M. Green and Stephen O. Wright, DDS.
Principal investigator: Kami Hanson
Dental Hygiene Department: Stephanie Bossenberger-James, Department Director
APPLICATION FORM (Attach to each copy of the proposal.)
INVESTIGATOR'S STATEMENT OF ASSURANCE
The attached investigation involves the use of human subjects. I understand the University policy concerning the use of human subjects and I agree:
1. To obtain informed consent of subjects who are to participate in this project;
2. To report to the Human Subjects in Research Committee any unanticipated effects on subjects which become apparent during the course, or as a result, of experimentation and the actions taken as the a result;
3. To cooperate with members of a committee charged with the continuing review of the project;
4. To obtain prior approval from the Committee before altering or amending the scope of the project or implementing changes in the approved consent form; and
5. To maintain documentation of consent forms and progress reports as requires by institutional policy.
PRINCIPAL INVESTIGATOR'S SIGNATURE
Fill in all blanks.
Does the subject group include healthy volunteers? _x__yes ___no
Does the subject group include ill persons? ___yes _x__no
Are subject groups excluded for medical reasons? __x_yes ___no
Are there vulnerable subject groups? ___yes _x__no
If yes, is the exclusion criteria for the study specified? _x__yes ___no
Are any subjects under the age of 18? ___yes _x__no
Are any subjects under the age of 12? ___yes _x__no
Are any subjects over the age of 70? ___yes _x__no
___Kami M Hanson_____ Dental Hygiene Department
PRINCIPAL INVESTIGATOR'S NAME (faculty) DEPARTMENT
STUDENT RESEARCHER'S NAME DEPARTMENT
__3920 University Circle, Ogden UT 84408-3920_____________
MAILING ADDRESS/MAIL CODE CITY, STATE, ZIP
________________________________________ _(801) 626-6130
PRINCIPAL INVESTIGATOR'S SIGNATURE TELEPHONE
_________________________________________ _(801) 626-6451
DEPARTMENT CHAIR'S SIGNATURE TELEPHONE