Tooth Whitening Evaluation With Cytotoxic and Genotoxic Effect of Commercial Whitening Toothpastes on Oral Mucosal Cells

Bleaching discolored vital teeth is one of the most popular aesthetic treatment in dentistry in the last decade. Teeth whitening can be performed by professionals/dentists in the dental office ("in-office") and by the patients themselves at home (over-the-counter). A generally available method for teeth whitening is to use toothpastes which contain whitening ingredients. This method presents commercial option to remove discolorations on the enamel surface of vital teeth. There are many commercially available dentifrices that contain whitening agents, such as abrasives, chemical or optical agents. It has been noticed that whitening agents added in toothpastes can provide whitening effect visible to human eye that can objectively be evaluated by using sprectrophotometers. The results of teeth whitening can also be obtained subjectively by observation and comparison to tooth shade guide. Also, these products must be used with caution as they may cause some negative effects, such as dentinal hypersensitivity, irritations, peeling/exfoliation, dry mouth, rougher teeth and cytotoxic and genotoxic effect on oral mucosa cells. Studies that have already been conducted with whitening agents are based on abrasives, peroxides, optical agents and activated charcoal.

The main objective in this study is to investigate the effectiveness of different brands of toothpastes with whitening effect and their performance (effect) on oral mucosa cells. As a measure of genotoxicity and cytotoxicity in cells, the number of micronuclei and other morphological changes of the nucleus are determined (micronucleus assay). Other specific objectives are to investigate the patient satisfaction with the characteristic of treatment such as final tooth color, color stability, length of treatment, comfort during treatment and overall participant satisfaction.

Sample description and study design for this research was performed at the School of the Medicine, University of Split, Croatia.

Respondents are the students and employees of the School of the Medicine University of Split, Croatia. They will be divided in groups where different types of whitening toothpaste will be used. One group will use control non-whitening toothpaste. All respondents will use the same toothbrush during the research. Before using whitening toothpastes, all participants will use the same non-whitening toothpaste for one month. All participants will sign informed consent for participation in the research. Their participation will be voluntary. Respondents will be able to refuse to participate in the research without any consequences.

This study is approved by Ethic Committee of the School of Dental Medicine, Zagreb, Croatia (09.2018.) and Ethic Committee of the School of the Medicine University of Split, Croatia (12.2017). The study is randomized, prospective clinical trial.

The participants will be randomly selected for the whitening toothpaste groups and for the control non-whitening group. A sample of cells from the buccal mucosa area will be taken from each patient prior using the toothpastes under test, 30 and 60 days after the beginning and 30 days after using the toothpastes under test. Color assessment will be performed four times using the Vita Easyshade digital spectrophotometer: T0- before treatment (initial); T1- 30 days after the beginning; T2- 60 days after the beginning and T3- 90 days after the beginning of the study (i.e. 30 days after completing the treatment). The color reading will be performed in the middle third of the labial surface of the tooth, in the same environment and with the same light conditions. The measurement will be performed on all vital six anterior maxillary teeth, free of caries and restorations. Participant's satisfaction with the treatment and the toothpaste used will be assessed using the prepared questionnaires.

Participants will use toothpastes under test for two months. Toothpaste will be applied twice a day, in the morning and in the evening, for three minutes for 1g (app. 2 cm). During the experiment, the examinees will not use any toothpaste other than the one under test. Participants will use no other agents for oral hygiene.

Eligibility Criteria:
Inclusion Criteria:

* age of 18 and older
* non smokers
* good oral and general health
* excellent oral hygiene
* vital six anterior maxillary teeth free of caries or restorations
* tooth shade A2 or darker
* no cervical lesions or prosthodontic treatments
* no periodontal disease

Exclusion Criteria:

* pregnant women
* breastfeeding women
* individuals with discolored teeth (tetracycline stain, fluorosis)
* tooth sensitivity
* history of allergy to any dental hygiene product
* individuals who had previously undergone any tooth whitening treatment