There has been an increasing demand for whiter teeth. Home-based whitening products with a bleaching action have become popular and are prescribed to people by the dentist or purchased over-the-counter. A variety of whitening products are available which include hydrogen peroxide, carbamide peroxide, sodium percarbonate, sodium hexametaphosphate, sodium tripolyphosphate, and calcium peroxide. These agents are supplied in different concentrations and are used with different methods of application (gel in tray, strips, paint-on gel, chewing gum, and mouthwash), which have varying application times and duration of treatment.
What was the research?
A systematic review to examine the available evidence on the different home-based chemically-induced bleaching agents for whitening teeth.
Who conducted the research?
The research was conducted by a team led by Prashanti Eachempati of Melaka-Manipal Medical College, Malaysia, on behalf of Cochrane Oral Health. Sumanth Kumbargere Nagraj, Salian Kiran Kumar Krishanappa, Puneet Gupta and Ibrahim Ethem Yaylali were also on the team.
What evidence was included in the review?
We included 71 randomised controlled trials, with 3,780 participants. These were adults who underwent tooth whitening procedures with various bleaching agents using different methods of application, length of application and duration of treatment. 26 studies compared a bleaching agent to placebo and 51 studies compared one bleaching agent to another bleaching agent.
What did the evidence say?
The bleaching agents whitened teeth compared to placebo over a short time period (from 2 weeks to 6 months), however the certainty of the evidence is low to very low.
The evidence currently available is insufficient to draw reliable conclusions regarding the superiority of home-based bleaching compositions or any particular method of application or concentration or application time or duration of use.
The most common adverse events were tooth sensitivity and oral irritation, which were reported with higher concentrations of active agents, although the effects were mild and transient.
Well-planned randomised controlled trials need to be conducted by standardising methods of application, concentrations, application times and duration of treatment.
How good was the evidence?
The overall certainty of the evidence was low to very low for all comparisons. This was because most of the comparisons were reported in single trials with small sample sizes and event rates. There was an unclear risk of bias in most of the trials.
What are the implications for dentists and the general public?
We found low to very low-certainty evidence over short time periods to support the effectiveness of home-based chemically-induced bleaching methods compared to placebo for all the outcomes tested.
We were unable to draw any conclusions regarding the superiority of home-based bleaching compositions or any particular method of application or concentration or application time or duration of use, as the overall evidence generated was of very low certainty. Well-planned randomised controlled trials (RCTs) need to be conducted by standardising methods of application, concentrations, application times, and duration of treatment.
What should researchers look at in the future?
Further research should be undertaken to know the effectiveness of home-based bleaching methods by conducting well-planned RCTs with more clarity and uniformity in the variables. In designing such clinical trials, the following needs to be considered.
- Evidence: the present evidence was insufficient to conclude that any of the comparisons of home-based bleaching methods are effective. Trials should focus on testing similar concentrations with similar methods of application. Trials should focus on both short-term and long-term benefits of treatment. Studies should also focus on patient-related outcomes and cost effectiveness. Furthermore, reports on clinical trials would be improved by following CONSORT recommendations.
- Population: inclusion criteria for clinical trials should be well defined. Trials should include both genders in equal distribution.
- Intervention: intervention should focus on similar concentrations used in earlier studies and similar application times with a longer follow-up. This will add on to the existing evidence pool allowing us to make robust conclusions.
- Comparison: various comparisons have been reported, but we found only single trials in most of the comparisons due to which the quality of evidence is very low. Hence, RCTs need to be conducted keeping in mind already published studies so that the number of trials for a particular comparison increase.
- Outcome: patient-reported outcomes were not considered in most of the trials. Cost effectiveness also needs to be added in the RCTs, which is of most interest to consumers.
Eachempati P, Kumbargere Nagraj S, Kiran Kumar Krishanappa S, Gupta P, Yaylali IE. Home‐based chemically‐induced whitening (bleaching) of teeth in adults. Cochrane Database of Systematic Reviews 2018, Issue 12. Art. No.: CD006202. DOI: 10.1002/14651858.CD006202.pub2.
This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Editorial Base.