Medical

Communication

Biosci. Biotech. Res. Comm. 10(2): 202-207 (2017)

Effects of green tea, calcium hydroxide and chlorhexidine

on chemical structure and tooth discoloration

Mehdi Vatanpour,

Sara Esmaili,

* Payman Mehrvarz Dar

and Hamed Zahedi Pour

Assistant Professor, Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran

Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran

Associated professor, Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran

Craniomaxillofacial Research Center, Tehran University of Medical Sciences

ABSTRACT

Natural and herbal substances are increasingly playing a signi cant role and gradually replacing chemical medica-

ments. Green tea has bene ts such as lower price, low toxicity and its anti-in ammatory properties is. The aim of

the present study was to study the effects of green tea, calcium hydroxide and chlorhexidine on chemical structure

changes and tooth discoloration. 60 single-rooted premolar teeth with no caries or  lling were collected and ran-

domly divided into 4 experimental groups (n=15). Group 1,was kept as control, group 2-4 treated with green tea,

calcium hydroxide and chlorhexidine, respectively. Each tooth was decoronated horizontally from 3mm below CEJ.

The crowns were used in part of the research dealing with tooth discolorations and roots for the part addressing

chemical structure changes. The samples were placed in distilled water and exposed to indirect sunlight to simulate

natural conditions until the end of experiment. The analysis of the tooth colors was done by VITA-easy shade spec-

trophotometer immediately on days 1, 7, 30 and 90 after placement. The infra-red spectra re ecting chemical struc-

ture of each sample was drawn by ATR-FTIR.Tooth discoloration on  rst day and third month showed no signi cant

difference between all study groups (P>0.05). Signi cant difference observed between positive control and green tea

groups after 7 days (P<0.05). A signi cant differences detected between positive control and the rest of groups after

30 days (P<0.05). In chemical structure change analysis signi cant difference was observed between green tea and

chlorhexidine with control group (P<0.05). These results suggested short term administration of these materials has

no side effect on teeth discoloration.

KEY WORDS: CALCIUM HYDROXIDE, CHLORHEXIDINE, GREEN TEA, TOOTH DISCOLORATION

202

ARTICLE INFORMATION:

*Corresponding Author:

Received 10

Feb, 2017

Accepted after revision 18

May, 2017

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Mehdi Vatanpour et al.

INTRODUCTION

Restoration of smile is one of the most challenging and

esthetically satisfying services a prosthodontist can ren-

der to a patient. Dental porcelain is used extensively

as a restorative material in a variety of dental restora-

tions, including all ceramic restorations, metal ceramic

crowns, and  xed partial dentures because of because

of its esthetic properties, durability, and biocompat-

ibility (Jain et al. 2013). Tooth discolouration creates a

range of aesthetic problems, and considerable amounts

of time and money are invested in attempts to improve

the appearance of discoloured teeth. Discolouration is

a more signi cant factor for many people in achiev-

ing an aesthetic smile than restoring their normal align-

ment within the arch (Sulieman 2008). Therefore, it is

important for dental professionals to have a thorough

knowledge and understanding of the etiology and clini-

cal features of tooth discolouration to select the most

appropriate treatment for each case (Ahmed and Abbott,

2012).

Any changes of tooth structure are likely to cause an

alteration in outward appearance of the tooth caused

by changes of light transmitting and re ecting proper-

ties (Mishra and Mishra, 2013). Some discolorations are

located on the outer surface of the tooth structure, oth-

ers are caused by stain taken up by the enamel or dentin,

and some occur during tooth development and result

in an alteration of the light transmitting properties of

the tooth structures (Nugalaet al. 2012). The exogenous

staining may occur due to the ability of the restoration

to adsorb or absorb stains in the oral cavity which may

be potentialized by surface conditions such as rough-

ness. Studies have been undertaken to evaluate the color

stability of composite restorations and it has been con-

cluded that composite resins are unable to retain the

color they possess at the time of insertion (Ghahraman-

loo et al. 2008). Crown discoloration related to endodon-

tic  lling materials is associated with the material time

to contact the tooth structure, as well as the potential

chromogenic materials used in the treatment (Xavier

et al. 2017).

There are many disinfectant solutions, with particular

advantages and disadvantages (Gomes et al. 2008). For

example, sodium hypochlorite (NaOCl) shows antimicro-

bial activity against a wide range of micro-organisms

and relatively good tissue solubility. However this irri-

gant has several disadvantages such as cytotoxicity, tis-

sue burning, bad taste and odor and discoloration of

patient’s clothes (Razmi et al. 2016). The materials com-

monly used in Endodontics for primary teeth are zinc

oxide eugenol, iodoform pastes, and calcium hydroxide

pastes (Krastl et al. 2013). In a study Xavier et al. (2017)

studied effect of zinc oxide, eugenol cement, Vitapex

and calcium hydroxide thickened with zinc oxide on

bovine tooth discoloration. Based on their report zinc

oxide and eugenol had higher discoloration. Vivacqua-

Gomes et al. (2002) observed a dark brown precipitate

when NaOCl was combined with chlorhexidine gel. Other

authors have reported the same type of discolouration

when NaOCl has been used with chlorhexidine solutions

(Bui et al. 2008, Akisue et al. 2010, Nassar et al. 2011).

Plants have always been common sources of medi-

cal agents. Antimicrobial, antifungal and anticancer

effects of many plants have been the subject of many

studies (Shakouie et al. 2014). In dentistry, herbal medi-

cines have been used as anti-in ammatory, analgesic

and antibacterial agents for many years (Shakouie et

al. 2014). Vinothkumar et al. (2013) have examined the

antibacterial effects of several herbal extracts including

Aloe barbadensis, Myristica frangrans, Terminalia che-

bula, Curcuma longa and Azadaricta indica as endodon-

tic irrigants. Green tea is obtained from the leaves of

young camellia sinensis tree. Its antibacterial activity is

due to inhibition of the DNA gyrase bacterial enzymes

by binding to the ATP binding sites of the ATPB subunit.

Green tea has antibacterial activity against E. faecalis

and it also has been known as a chelating agent (Naderi

et al. 2011).

Despite previous researches on anti-bactericidal

activity of the green tea, there is scarce information on

its tooth discoloration activity. So, the aim of the cur-

rent study was to determine effects of green tea, calcium

hydroxide and chlorhexidine on chemical structure and

tooth discoloration.

MATERIALS AND METHODS

This in vivo study is performed on 60 single-rooted pre-

molar teeth with no caries or  lling were collected and

randomly divided into 4 experimental groups (n=15). All

the samples were extracted for the purpose of orthodon-

tic treatments approximately a month before the study.

Each tooth was decoronated horizontally from 3mm

below CEJ. The crowns were used in part of the research

dealing with tooth discolorations and roots for the part

addressing chemical structure changes. After cleaning

the root canal section and pulp chamber with ultrasonic

and NaOCl (5.25%), EDTA (17%) was applied to remove

smear layer for one minute, then the canals rinsed with

NaOCl. The medicaments got placed in pulp chambers

and the apical opening of the canals was sealed with

glass ionomer. Premolar teeth randomly allocated into

4 experimental groups: group 1, kept as control, group

2-4 treated with green tea, calcium hydroxide and chlo-

rhexidine, respectively. The samples were placed in dis-

tilled water and exposed to indirect sunlight to simu-

late natural conditions until the end of experiment. The

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS EFFECTS OF GREEN TEA, CALCIUM HYDROXIDE AND CHLORHEXIDINE ON CHEMICAL STRUCTURE 203

Mehdi Vatanpour et al.

phosphate/amid ratio between samples was determined

at day 1, 7, 30 and 90.

The analysis of the tooth colors was done by VITA-

easy shade spectrophotometer at day 1, 7, 30 and 90. In

order to assimilate the samples and reach pulpal surface

required for the chemical structure analysis, each tooth

was sectioned both in vertical and horizontal directions

by D&Z diamond disc. Each root provided 1 sample per

group (4 samples in total). The infra-red spectra re ect-

ing chemical structure of each sample was drawn by

ATR-FTIR. Each sample was located in its relevant well

 lled with medicaments and placed in incubator. Data

is analyzed by one-way analysis of variance (ANOVA)

using SPSS 16.0 for Windows (SPSS, Inc., Chicago, IL,

USA). For treatment showing main effect by ANOVA,

means compared by Mann-Whitney (parameteric) and

Kruskal-Wallis (nonparametric) tests. P<0.05 was con-

sidered as signi cant differences between treatments.

RESULTS AND DISCUSSION

As seen in the table 1, no signi cant difference observed

on color change on  rst day (P>0.05). A signi cant dif-

ference detected between green tea and positive control

with the other groups after 7 days (P<0.05). No signi -

cant difference detected between positive group com-

pared to the other groups on day 30 (P>0.05).

As seen in  gure 2, no signi cant change observed

on the AE of the color change on day 1 and 90 between

the groups (P>0.05). Signi cant difference detected

between positive control and greet tea compared to the

other groups on days 7 and 30 (P<0.05)

Tooth discoloration is a possible side effect of endo-

dontic treatment of anterior teeth (Krastl et al. 2013).

Hemorrhage inside the pulp cavity, residual pulpal tissue

as well as materials used during root canal treatment

are the most usual causes for discoloration (Ahmed et

al. 2012). In addition obturating materials, intracanal

medicaments and temporary  lling materials may cause

also of internal tooth staining (Lenherr et al. 2012). As

far as the intracanal medicaments concerns, their role

in the success of the endodontic treatment is important,

since they maintain the root canals disinfected for the

time interval between instrumentation and  nal root

canal obturation (Silveira et al. 2011). Calcium hydrox-

ide plays an important role in endodontics due to its

ability to induce hard tissue formation, its antibacterial

effect and its ability to act as a physical barrier to pre-

vent root canal reinfection (Mohammadi and Dummer,

2011).

These properties derive from its high pH (up to 12.5),

which neutralises lactic acid from the osteoclasts, thus

preventing a dissolution of the mineral components of

dentin. Moreover, it could also activate alkaline phos-

phatases which play an important role in hard tissue

formation (Mohammadi and Dummer, 2011). One of the

most important antimicrobial agents in dentistry is chlo-

rexidine. The most signi cant properties that justify the

use of chlorexidine as an intracanal medicament are its

antimicrobial activity against Grampositive and Gram-

negative microorganisms, as well as its residual antimi-

crobial ability on the dentin surface after remaining for

at least one week within the root canal (substantivity)

(Mohammadi and Abbott, 2009).

Moreover, chlorexidine is effective against bacteria

that are resistant to Ca(OH)

and mainly E. faecalis; this

property justi es the use of chlorexidine in retreatments,

where such bacteria are usually found. However, clini-

cal studies have recorded tooth staining by chlorexidine,

especially when it is used as a mouthrinse for periodontal

treatment (Gomes et al. 2013). The most possible stain-

ing mechanisms of tooth discolorations due to chlorex-

idine application seem to be non-enzymatic browning

(Maillard reactions) and formation of pigmented black

metal sul des (Gomes et al. 2013).

Nevertheless, the corresponding phenomenon has

not been investigated in cases when chlorexidine is used

for endodontic purposes. On the contrary, the stain-

ing potential of Ca(OH)

has not been clearly de ned,

as its discoloration ability may depend on its chemi-

cal composition(pure Ca(OH)

powder, or commercial

Ca(OH)

pastes whose some contents may be able to dis-

color teeth). Nevertheless, some latest studies have con-

cluded that Ca(OH)

has indeed a discoloration poten-

Table 1. the AE of discoloration change in different

gouprs

Groups Time (day) Mean ± Sd C.V

Control

1 1.00 ± 0.23 0.23

7 1.53 ± 0.27 0.17

30 3.79 ± 0.48 0.12

90 4.80 ± 6.71 1.39

calcium hydroxide

1 1.36 ± 1.64 1.20

7 1.84 ± 1.62 0.88

30 1.42 ± 1.65 1.16

90 2.50 ± 5.88 2.35

Chlorhexidine

1 0.54 ± 0.61 1.12

7 2.01 ± 1.58 0.78

30 2.44 ± 1.96 0.80

90 2.50 ± 2.98 1.19

Green tea

1 0.94 ± 0.58 0.61

7 0.91 ± 0.50 0.54

30 0.51 ± 0.16 0.31

90 0.35 ± 0.37 1.05

204 EFFECTS OF GREEN TEA, CALCIUM HYDROXIDE AND CHLORHEXIDINE ON CHEMICAL STRUCTURE BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

Mehdi Vatanpour et al.

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS EFFECTS OF GREEN TEA, CALCIUM HYDROXIDE AND CHLORHEXIDINE ON CHEMICAL STRUCTURE 205

FIGURE 1. The ATR-FTIR results of the samples. Green: control, orange: green tea, blue: calcium

hydroxide, Red: chlorhexidine; Figures from up to down: days 1, 7, 30 and 90.

Mehdi Vatanpour et al.

206 EFFECTS OF GREEN TEA, CALCIUM HYDROXIDE AND CHLORHEXIDINE ON CHEMICAL STRUCTURE BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

tial, which might not have been extensively taken into

account up to date (Krastl et al. 2013). The exact stain-

ing mechanism of Ca(OH)

is not clearly known; it has

been implied that it is more likely due to any additional

components, i.e. bismuth carbonate, that usually exist

in many commercially-prepared Ca(OH)

pastes, while as

regards pure Ca(OH)

powder, there has not been a con-

vincing explanation.

It is a common knowledge that many intracanal

medicaments may result in tooth discoloration, but as

regards Ca(OH)2, its possible impact on color alterations

remains unclear. Day et al. (2011) recorded discoloration

of replanted teeth after avulsion, which had been treated

with Ca(OH)2. The in uence of Ca(OH)2 on discoloration

may be more severe in teeth with vital pulpal tissue,

possibly because of the existence of erythrocytes which

contribute to color changes after Ca(OH)2-induced hae-

molysis (Addy and Moran, 1995). The calcium hydrox-

ide dressings varied in their discoloration ability. Pure

calcium hydroxide and Ultracal XS did not show any

discoloration or difference to the negative controls at

any time. Interestingly, the Apex- Cal specimens showed

an increase in their DE values in the second half of the

observation period. The difference to all the other cal-

cium hydroxide materials was statistically signi cant

after 12 months (Lenherr et al. 2012).

Moghbel et al. (2011) investigated the antibacterial

effect of green tea at concentrations of 1%, 0.2% and

0.5% compared with chlorhexidine 0.2%. According to

the obtained results, through an increase in the concen-

tration of green tea, the effect of this extract on Strep-

tococcus mutans and Staphylococcus aureus increases,

so that 1% concentration of tannin in green tea extract

with chlorhexidine has a similar effect in the reduction

of mouth aerobic bacteria. Therefore, instead of using

chemical mouthwashes such as chlorhexidine, this herbal

mouthwash is recommended especially for children and

pregnant women. Although the bacterial strains used in

their study are not identical to this one, in both studies,

with an increase in concentration of green tea extract,

their antimicrobial activity is also increased (Moghbel

et al. 2012).

Neyestani et al. (2007) investigated the effect of

green tea in comparison with black tea on Streptococ-

cus pyogenes strains; they also stated that an increase

in the concentration of green tea extract increases its

effect, although in their research the studied pathogens

were different from this study. Also according to their

results, the effect of green tea in similar concentrations

was more than that of black tea on micro-organisms. In

conclusion, these results suggested short term admin-

istration of these materials has no side effect on teeth

discoloration.

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