Effect of 35% hydrogen peroxide on in-office bleaching against changes in tooth enamel hardness: Literature review


 

 
Corresponding author: 
Asy-Syifa Brillian Avicenna 
brillianavicenna@gmail.com  
South East Asia Nursing Research, Vol 4 No 1, March 2022 
ISSN:2685-032X 
DOI: https://doi.org/10.26714/seanr.4.1.2022.47-50  

 
 

 
 
 
 
 

 

Review Article 
 

Effect of 35% hydrogen peroxide on in-office bleaching against changes in 
tooth enamel hardness: Literature review  
 
Asy-Syifa Brillian Avicenna1, Christina Mahardika1, Lira Wiet Jayanti1 

1 Faculty of Dentistry, Universitas Muhammadiyah Semarang, Indonesia 

 
Article Info  Abstract 

Article History: 
Submitted: Feb 14th 2022 
Accepted: March 5th 2022 
Published: March 29th 2022 
 
Keywords:  
hydrogen peroxide; 
bleaching; enamel hardness 

 Teeth bleaching is one of the treatments for teeth discolouration. Teeth 
bleaching can do in-home or in-office. The material for that use in-office 
bleaching is 35% hydrogen peroxide. Hydrogen peroxide is a chemical 
compound that is tough and has a micro molecule that can easily penetrate 
enamel tissue and dentin tissue. Bleaching with hydrogen peroxide in-office 
is now more attractive because can be faster to see the result. Bleaching with 
hydrogen peroxide when done repeat will make teeth more sensitive, and 
damage enamel tissue and dentin tissue.  The objective of this study is to 
know the influence of in-office bleaching using 35% hydrogen peroxide on 
microhardness enamel.  This research is made with a literature review with 
search engine google scholar, PubMed, and science direct. The results of 10 
articles show the effectiveness of teeth discolouration after bleaching using 
35% hydrogen peroxide in-office.  The reduction in enamel microhardness 
seen using SEM, knob and Vickers is visible although not significant. Based 
on the literature review research that has been carried out, it can be 
concluded that there is a reduction in enamel hardness after the in-office 
bleaching process by using 35% hydrogen peroxide. 

 

INTRODUCTION  

Teeth discoloration is part of the aesthetic 
problem in society. Teeth discoloration can 
be caused by intrinsic factors (the 
incorporation of substances inside enamel 
and dentin such as tetracyclin, imperfect 
dentinogenesis, fluorosis, dental trauma and 
drugs) and extrinsic factors caused by 
agents that cause changes in enamel 
(cigarettes, tea, and coffee).1 

Teeth bleaching is one of the measures taken 
to deal with tooth discoloration. The 
material commonly used for in-office 
bleaching is hydrogen peroxide.2 Hydrogen 

proxide has the ability to dissociate into 
reactive oxygen species (ROS) which is 
widely used in tooth  bleaching. Hydrogen 
peroxide is used for in-office bleaching 
because of its stronger properties than 
carbamide peroxide.3 

The bleaching process occurs when low-
molecular hydrogen peroxide diffuses 
through enamel and dentin, then releases 
reactive oxygen species (ROS) that react or 
bind to other weak substances. The 
penetration of oxidative agents in the tooth 
structure will damage the dye molecules so 
that it will give a brighter result to the tooth. 

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South East Asia Nursing Research, Vol 4 No 1, March 2022/ page 47-50 48 

 

Asy-Syifa Brillian Avicenna / Effect of 35% hydrogen peroxide on in-office bleaching against changes in tooth 
enamel hardness: Literature review 

This process is usually called a redox3 
reaction.  

The high peroxide content makes the pH 
level of the teeth decrease so that it can 
cause changes in the enamel including 
increased roughness, decreased micro 
hardness of enamel, decreased strength of 
enamel and changes in the composition of 
enamel.4 Hydrogen peroxide used in 
dentistry is between 5% to 38%. The 
process of bleaching teeth produces the 
effect of reducing the hardness of enamel, 
increasing tooth sensitivity and erosion.5 

Research conducted in 2015 by De Paula 
using 35% hydrogen peroxide in in-office  
bleaching, teeth in contact with saliva can 
cause demineralization and dehydration 
processes after a few days post-bleaching.6 
In in-office  bleaching, the duration of 
contact with bleaching agents has a greater 
effect than the concentration of bleaching 
agents.  One of the effects that appears after 
bleaching teeth is a decrease in the level of 
micro-hardness in enamel.7 Enamel 
hardness can be tested with Knoop or 
Vickers, SEM (Scanning Electron 
Microscopy), and EDS (Energydispersive X-
ray Spectroscopy).8 

METHOD 

The research is in the form of literature 
review by collecting a number of data on 
35% hydrogen peroxide in in-office 
bleaching related to changes in enamel 
hardness that have been carried out in 
previous studies. The research results listed 
were obtained using keywords in each 
database (google scholar, PubMed.  And 
science direct) according to the problem of 
the research problem.  

The results of all databe obtained 489 
articles which were then screened according 
to the inclusion and exclusion criteria from 
2011-2021, accessible ful text, in the form of 
research articles and using English and 
Indonesian. Furthermore, an assessment of 
the feasibility of a copy of the ful text is 

carried out where a  review  of the entire 
article is carried out and then it is calculated 
with  a critical appraisal  to find out whether 
the relevant article is used to answer 
research problems that have been 
formulated in accordance with the research 
objectives. The article was analyzed for 
research problems and then concluded. 

RESULT 

Based on the search results of 3 databases, 
namely Google scholar, PubMed, and science 
direct, there are 10 articles related to 35% 
hydrogen peroxide. The results of 10 
articles show the effectiveness of teeth 
discoloration after bleaching using 35% 
hydrogen peroxide in-office.  The reduction 
in enamel micro hardness seen using SEM, 
knob and Vickers is visible although not 
significant. The reduction of enamel micro 
hardness can be caused by several things.  

DISCUSSION 

The in-office bleaching process on teeth has 
been carried out in the past 100 years ago. 
The in-office bleaching method is currently 
widely practiced because of its advantages 
such as, it does not require a long time, and 
can minimize taboos in food consumption. A 
commonly used material for in-office 
bleaching is usually hydrogen peroxide. 
Some also use non-additives in the 
bleaching process.9 

Hydrogen peroxide is a strong oxidizing 
agent and can cause the formation of other 
highly effective bleaching agents such as 
perihydroxyl anions (HO) and hydroxyl 
radicals (OH-). Hydrogen peroxide material 
can cause burns or irritation to the gingiva 
if it accidentally hits soft tissues, because 
hydrogen peroxide has unstable and hard 
properties.10 

In the redox reaction process, hydrogen 
peroxide which has small molecules can 
easily diffuse into the enamel matrix layer. 
The free radicals then interact with organic 
molecules to achieve stability. The 



South East Asia Nursing Research, Vol 4 No 1, March 2022/ page 47-50 49 

 

Asy-Syifa Brillian Avicenna / Effect of 35% hydrogen peroxide on in-office bleaching against changes in tooth 
enamel hardness: Literature review 

effectiveness of bleaching is influenced by 
several things such as stains on teeth, pH, 
length of application time, temperature, 
hydrogen peroxide concentration, additives 
(rsa enhancing agents), and other factors 
(age and gender).11 

Hydrogen peroxide is active at an alkaline 
pH. However, a high pH can cause damage 
to the surface of tooth enamel.5 The 
temperature setting in the in-office 
bleaching  process has an effect on removing 
ROS so that hydrogen peroxide 
performance increases up to 2x.5 Teeth 
bleaching with pH 5, pH 7, pH 8, pH 9, and 
pH 10 resulted in, teeth  bleaching with pH 
10  visible results were very significant, but 
side effects that appeared such as a 
significant decrease in enamel surface 
hardness were also.12 The length of time of 
application also affects the bleaching 
process.  Teeth repeated 3x15 minutes using 
35% hydrogen peroxide produce a brighter 
tooth color than using 40% hydrogen 
peroxide once repeated.13 

Some of the effects arising from the 
bleaching process using 35% hydrogen 
peroxide include increasing tooth 
sensitivity, erosion, changing the hardness 
of enamel, hard tissue structure, and 
reducing micro hardness in enamel. The 
change is due to the demineraly process 
caused by redox reactions.14  

The reduction in enamel hardness seen 
using the vickers tool, the presentation of 
micro hardness in enamel ranges from 22.1 
to 0.4 values. The use of 35% hydrogen 
peroxide in in-office bleaching results in a 
change in the structure of enamel hardness 
seen using SEM. Side effects of bleaching can 
be minimized by using desensiting 
materials. The use of LEDs in applications 
can also minimize side effects that occur in 
teeth.15 

The bleaching process begins with a 
subjective and objective examination and 
then determines the diagnosis of treatment 
and documentation before treatment. The 

patient is explained to be the cost and time 
of treatment, then the patient is instructed 
to fill in the informed concent. The 
installation of a check rectractor is done to 
protect the lips and as a marker to facilitate 
the part to be treated. Prosilaxis actions 
using brushes and pumice are performed on 
the teeth to be bleached. This action is useful 
for removing debris or dirt that is still 
attached to the teeth. The initial color of the 
teeth is assessed First use the Vita Shade 
Guide and the patient is educated to keep 
the mouth open during the procedure.  
Cotton rollers are applied along the tooth 
fomix to be bleached.  The application of 
opal dam green is 4-6 mm long and 1.5-2 
mm thick on the gingiva of the cervical part 
of the tooth to be bleached.  Irradiation with 
light curing is carried out for 20 seconds in 
each jaw. Bleaching material is applied to 
teeth 0.5-1 mm thick on the labial surface 
then incisal. Apply for 20 minutes until the 
desired color is reached.16 

 The bleaching material is cleaned by 
disuction and using cotton pellets, after 
which the patient is instructed to gargle 
with warm water. After all the procedures 
are performed, the color of the teeth is 
checked again using the vita shade guide and 
documentation is carried out again after 
bleaching.16 

CONCLUSION 

Based on the literature review research that 
has been carried out, it can be concluded 
that there is a reduction in enamel hardness 
after the in-office bleaching process by using 
35% hydrogen peroxide which is influenced 
by several factors, namely, the pH level of 
the hydrogen peroxide content, the size of 
the hydrogen peroxide presentation 
content, the length of application time, the 
number of repetitions and temperature. 

ACKNOWLEDGMENTS 

The author would like to thank all those 
who have helped and supported the review 
process and writing this research article. 



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Asy-Syifa Brillian Avicenna / Effect of 35% hydrogen peroxide on in-office bleaching against changes in tooth 
enamel hardness: Literature review 

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