In accordance with Herodotus (484–425 BC), Chios Mastic had been beneficial to oral cavity hygiene. In De Materia Medica, Dioscorides (40–90 AD) mentions that Chios Mastic is useful for cleaning the teeth and for odouring the mouth when chewed. Other relevant citations have been made during the Ottoman period and they last till our times. Undoubtedly, Chios Mastic is essential for the oral hygiene, due to its antimicrobial action against many oral bacterial species. Countless trials have indicated the strong relationship of Chios Mastic with antiplaque effects, chronic periodontitis, prevention of caries, peridental disorders, treating of oral malodor and gum disease, and other oral cavity conditions.

Study 1:

Watanabe et al in 1973 performed a double blind randomized control trial to evaluate the clinical and microbiological activity of Chios Mastic oil dentifrice on chronic periodontitis, by using sonic toothbrush. Particularly, 22 volunteers with chronic periodontitis were randomly divided into 2 groups; the experimental group that used Chios Mastic oil dentifrice and the sonic toothbrush (11 patients: 6 males, 5 females, average age 63.2 years) and the placebo group that used the sonic toothbrush without Chios Mastic oil dentifrice (11 patients: 4 males, 7 females, average age 55.5 years). 3 sites per each were subjected. Moreover, at baseline and at 2, 4 and 12 weeks, clinical measurements were carried out by using clinical parameters. What is more, at baseline and at 4 and 12 weeks, subgingival plaque was collected. It is worth mentioning that a quantitative analysis of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola, Tannerella forsythia, Prevotella intermedia was performed by using real-time polymerase chain reaction (PCR). Interestingly, there was no remarkable difference among the 2 groups regarding the clinical conditions at baseline. After using sonic toothbrush and dentifrice for 2, 4 and 12 weeks in both groups, notable reduced inflammation was observed. Chios Mastic group demonstrated an important amelioration on swelling, bleeding, redness of gingiva and plaque accumulation, compared to the control. Solely in Chios Mastic group a significant suppression of P. gingivalis and red complex in the ratio against total bacteria cell counts after 4 week treatment, and P. gingivalis and P. inter- media after 12 week treatment happened. The research group was notably superior to the placebo, with regards to the suppression of P. gingivalis at 12 weeks after treatment. Conclusively, the present study suggests that sonic toothbrush and dentifrice may be beneficial for chronic periodontitis, and the useful effect for chronic periodontitis may induce the anti-periodontal-pathogen by Chios Mastic essential oil 81.

Mastic oil

Study 2:

In 1985 and 1986, Topitsoglou et al showed that if Chios Mastic is systematically used, it can lead to a significant reduction in the amount of formatting or already formed dental plaque. In order this trial to be materialized, 10 volunteers (University students) participated, having low caries rate, and were assigned in 2 groups. More specifically, the first group chewed Chios Mastic for a duration of 10 days, and the other group chewed a placebo gum. As a result, the amount of microbial plaque was reduced in a large extend in the Chios Mastic group. Thus, the commodity can be used for preventing caries, peridental disorders and oral cavity conditions 82 83.

Study 3:

Farella et al (2001) focused on examining the effects of prolonged gum chewing on pain, fatigue and pressure tenderness of the masticatory muscles. For this reason, 15 women without temporomandibular disorders were asked to conduct one of the next chewing tasks in 3 distinguished sessions: chewing a very hard gum (Chios Mastic), chewing a soft gum, and empty-chewing with no bolus. The duration of unilateral chewing of gum or empty chewing was equal to 40 minutes at a constant rate of 80 cycles per minute. Perceived muscle pain and masticatory fatigue in each session, were rated on visual analog scales before, during, and after chewing. Moreover, the evaluation of pressure pain thresholds of masseter and anterior temporalis muscles took place before and right after the chewing tasks, and again after 24 hours. The scores of the visual analog scales for pain and fatigue were remarkably higher solely during the hard gum chewing, and after 10 minutes of recovery they were again reduced, almost to their baseline values. For the pressure pain thresholds no significant alterations were observed, after hard or soft gum chewing. Ergo, the findings imply that the jaw muscles recover rapidly from prolonged chewing activity in subjects without temporomandibular disorders 84.

Study 4:

Another study group researched 6 commercial chewing gums, including Chios Mastic, to evaluate human response to gum of different rheological properties. Six elderly subjects presenting a broad range of dental conditions and 6 dentate younger adults, participated in the trial. To assess the viscoelastic modifications during chewing a simple bench test for measuring the consistency of chewed gums was used. The results showed relationships between the rheological properties of various gums and the modulation of chewing in people of different age groups. Additionally, there were fluidity and viscosity differences between natural Chios Mastic and the commercial gums containing synthetic material 85.

Study 5:

In a study conducted in 2003 in Japan, the antiplaque effect of Chios Mastic chewing gum was examined. More precisely, 20 dental students who were both systemically and periodontally healthy were the subjects of the trial. The effects of Chios Mastic were assessed from 2 double-blinded, randomized studies. Specifically, in the first test, the inhibitory activity of Chios Mastic on bacteria in saliva following its use was compared to a placebo gum, after mechanical toothbrushing. Saliva samples were collected at the end of 1, 2, 3, and 4 hours and further handled. In the second examination, the assessment of the effects of Chios Mastic on de novo plaque formation on tooth surfaces and gingival inflammation took place, over a 7-day period without mechanical oral hygiene, following random use of either Chios Mastic or placebo gum. The results indicated that the total number of bacterial colonies was remarkably decreased during the 4 hours of chewing Chios Mastic compared to the placebo gum. Additionally, the Chios Mastic group showed a notably lowered plaque and gingival index compared to the placebo. To sum up, v chewing gum is a beneficial antiplaque agent in decreasing the bacterial growth in saliva and plaque formation on teeth 86.

Study 6:

In 2006, a research group from Turkey showed that Chios Mastic possesses significant in vitro and in vivo antibacterial effect against S. mutans and mutans streptococci, and it may be a valuable adjunct in the prevention of caries. Specifically, clinical studies were conducted on 25 periodontally healthy individuals. Saliva samples were taken from the subjects immediately before and after Chios Mastic and placebo gum chewing for 15 minutes. Moreover, saliva samples were collected every 30 minutes as well. The results demonstrate that the bacteria number was notably decreased in saliva samples taken after chewing Chios Mastic, in comparison with the placebo 87.

Study 7:

In 2006, Sterer investigated the antimicrobial activity of Chios Mastic, against Porphyromonas gingivalis, which is responsible for periodontal diseases and oral malodor production. Chios Mastic methanolic extract caused inhibition zones, suggesting that it may be utilized as a potential non-toxic agent in treating oral malodor and gum disease 88.

Study 8:

Aksoy et al (2007) performed a study to determine antibacterial activity of chewing Chios Mastic against the salivary levels of Streptococcus mutans, the total number of viable bacteria, and lactobacilli in patients undergoing therapy with fixed orthodontic appliances. In particular, the levels of S. mutans, lactobacilli, and total bacteria were estimated before and after chewing Mastic, and the antibacterial effects of chewing Chios Mastic against these microorganisms in saliva were compared with a placebo. Additionally, the counts for orthodontically treated subjects were assessed before chewing gum, just after chewing gum, and after 45, 75, 105, and 135 minutes as well. Further analysis was followed, and the total number of viable bacteria was measured. The results demonstrated that just after chewing Chios Mastic for 15 minutes, a notable reduction of total bacteria and S. mutans was observed. The decrease in lactobacilli was not important at later first stage. Nonetheless, after 135 minutes, there was a sifnificant reduction of S. mutans, total viable bacteria, and lactobacilli in the buccal cavity after chewing Chios Mastic compared to the placebo. Chewing Chios Mastic lowered the total viable bacteria, S. mutans, and lactobacilli in saliva in orthodontically treated patients with fixed appliances. Therefore, Chios Mastic might be of great value in preventing caries lesions 89.

Study 9:

In 2009, a study team explored the comparison of the effect of Chios Mastic and a xylitol chewing gum on remineralization of caries-like lesions in situ. The results show a reduction in demineralized surfaces in the subjects. Conclusively, chewing both Chios Mastic and xylitol chewing gum enhanced the remineralization of caries-like lesions, with similar effects 90.

Study 10:

In 2009, a study group evaluated the biological action of solid and liquid types of Chios Mastic, by cytotoxicity against fibroblasts, radical scavenging activities and inhibitory effect on cell death of oral polymorphonuclear leukocytes. The product demonstrated selective antibacterial action against Porphyromonas gingivalis and Prevotella melaninogenica, and no anti-HIV effect. Chios Mastic caused apoptotic cell death. Interestingly, the cytotoxicity of the commodity against leukemic cells was not diminished during storage. The above results suggest the potential advantageous activity of Chios Mastic in oral health 91

Study 11:

Al Mofarji et al (2013) made an assessment in the antibacterial effect of Chios Mastic against the most common aerobic oral bacteria, focusing on oral streptococci. Particularly, 10 individuals (males and females of 18-60 years old) were randomly assigned to 1.5 grams of Chios Mastic chewing for 45 minutes. A collection of mouth washes took place before and after chewing for further processing. The results indicated that after chewing Chios Mastic, the total bacterial count for staphylococci, Neisseria and oral streptococci were significantly decreased 92.

Study 12:

In 2014, Biria et al aimed in evaluating the effects of three types of gums on the level of Mutans streptococci, Lactobacilli and pH of the saliva. Therefore, 42 students (20- 30 years old) were assigned to three parallel groups. Each group separately used pure Chios Mastic, xylitol mastic gum and probiotic mastic gum for 3 weeks. The number of microorganisms and pH of the saliva were measured before and after the trial. The level of Mutans streptococci posed a remarkable decrease compared to its baseline value in all groups. The salivary Lactobacillus count was augmented in the groups using pure Chios Mastic and xylitol gum, however it was lower in the probiotic type group, notwithstanding that the modifications were notable solely in the probiotic gum team. Ergo, after using all mastic gums for 3 weeks, a notable drop was observed in the number of Mutans streptococci in the saliva 93.

Study 13:

Lee et al (2014) examined the protective action of Chios Mastic against H2O2-induced oxidative stress and assessed the autophagic properties caused by Chios Mastic in human keratinocytes. Interestingly, the pretreatment with Chios Mastic notably lowered apoptosis in H2O2-exposed HaCaT cells, it enhanced the degradation of caspase-3, caspase-8, and caspase-9; and it caused the formation of the processed PARP. An increase in vesicle formation was caused by Chios Mastic treatment, in comparison with the control group. There was a decrease in the level of p62 and the conversion of LC3-I to LC3-II underwent an augmentation in Chios Mastic treated HaCaT cells. Moreover, Chios Mastic led to increased cleavage of ATG5-ATG12 complex. To wrap up, Chios Mastic assists in the survival of the cells under stressful conditions, by preventing apoptosis and promoting autophagy. Furthermore, evidence is provided to support the antioxidant activity of Chios Mastic in vitro 94.

Study 14:

Karygianni et al (2014) examined the antimicrobial activity of natural plant and fruit extracts of Mediterranean origin against various microbial species. Five different extracts from Olea europaea, Chios Mastic, and Inula viscosa were tested against ten bacteria and one Candida albicans strain. Two antimicrobial assays—the minimum inhibitory concentration (MIC) assay and the minimum bactericidal concentration (MBC) assay— were applied. Total Chios Mastic extract was effective against all of the microorganisms with MIC values ranging from 0.02 mg /mL (P. gingivalis) to 10mg/ mL. The mean MBC values were between 0.07 mg/ mL (P. gingivalis, P. micra) and 10.00 mg/ mL (S. mutans, S. sobrinus, E. faecalis, C. albicans, and E. coli). extract concentrations between 0.07 and 2.50 mg /mL exerted bactericidal effect mainly on strict anaerobic, Gram-negative bacteria (P. gingivalis, P. intermedia, and F. nucleatum). Overall, Chios Mastic extract showed considerable antimicrobial activity against oral microorganisms, especially Gram- negative anaerobic bacteria, and could therefore be considered as alternative natural anti-infectious agent which could be used against periodontitis 95

Study 15:

   The importance of masticatory activity from both an etiopathogenic and therapeutic perspective in orthodontics was investigated by Makaremi et al (2016). The authors conducted a comparative analysis of alveolar expansion using a fixed orthodontic appliance and its development between control subjects and subjects performing intense daily chewing exercises with Chios Mastic. This gum has two advantages: it has been proved to be very effective and there are no ethical issues with its use, as it is a natural product without any contraindications. They found that the subjects who chewed hard gum, the masticatory forces improved the stability of the molar expansion and straightened the molar axes, indicating the positive relationship between daily chewing of hard gum and maxillary transverse growth. Therefore, the clinical implication was that chewing exercises would allow the subjects to achieve a more balanced occlusal function and dentofacial development 96.

Study 16:

In a recent study published in the J Periodontol (Koychev el al, 2017), the antimicrobial properties of Chios Mastic extract on commensal and pathogenic oral bacteria, as well as its possible cytotoxic effect toward cells of epithelial and mesenchymal origin, were evaluated and compared with the common antimicrobial agents hydrogen peroxide (H2O2) and chlorhexidine digluconate (CHX). Oral and periodontal pathogens (Porphyromonas gingivalis, Streptococcus mutans], Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Prevotella intermedia, and Prevotella nigrescens) were treated with different concentrations of Chios Mastic extract, 3% H2O2, and 0.2% CHX. The cytotoxic effect of Chios Mastic extract was also tested on four cell lines of epithelial and mesenchymal origin. The results of the study showed that the Chios Mastic extract led to significantly (P ≤0.016) increased inhibition of the tested periodontal pathogens compared with H2O2. Chios Mastic extract showed beneficial effects on cell viability because viability values of tested cells were significantly (P ≤0.016) lower for cells treated with CHX and H2O2 compared with Chios Mastic extract- treated cells after stimulation for 2, 4, and 6 hours. It was concluded that Chios Mastic extract can be used, without side effects and the appearance of drug resistance, as an alternative, safe, natural antibacterial agent in the prevention of periodontal disease 97.

Chios Mastic

81. Watanabe H., Hagiwara S., Fukuda M., Yuichi I., Tamura N., Suzuki M., Kawasaki D., Fukahori M. [1973]: Double blind randomized control test for the usefulness of mastic compound dentifrice against periodontitis under using sonic toothbrush journal title. Yakuri To Chiryo, 38 (10): 915-925.

82. Topitsoglou-Themeli V., Dangalis P., Lambrou D. [1984]: Chios Mastic and oral hygiene I: A possible measure for decrease microbial plaque formation. Hell. Stom. Chron., 28: 166-170.

83. Topitsoglou-Themeli V., Kolokotronis A., Dangalis P., Lambrou D. [1985]: Chios Mastic and oral hygiene II: Differentiation in microbial plaque formation. Redodontia., 2: 56-59.

84. Farella M., Bakke M., Michelotti A., Martina R. [2001]: Effects of prolonged gum chewing on pain and fatigue in human jaw muscles. Eur. J. Oral Sci., 109 (2): 81-85.

85. Anastassiadou V., Siovas S. [2002]: Modulation of chewing rhythms to changes in viscoelasticity of chewing gums in people with different age and dental status. Stomatologia, 59 (1): 39-49.

86. Takahashi K., Fukazawa M., Motohira H., Ochiai K., Nishikawa H., Miyata T. [2003]: A pilot study on antiplaque effects of mastic chewing gum in the oral cavity. J. Periodontol., 74 (4): 501-505.

87. Aksoy A., Duran N., Koksal F. [2006]: In vitro and in vivo antimicrobial effects of mastic chewing gum against Streptococcus mutans and mutans streptococci. Arch. Oral Biol., 51 (6): 476-481.

88. Sterer N. [2006]: Antimicrobial effect of mastic gum methanolic extract against Porphyromonas gingivalis. J. Med. Food, 9 (2): 290–292.

89. Aksoy A., Duran N., Toroglu S., Koksal F. [2007]: Short-term effect of mastic gum on salivary concentrations of cariogenic bacteria in orthodontic patients. Angle Orthod., 77 (1):124-128.

90. Biria M., Malekafzali B., Kamel V. [2009]: Comparison of the effect of xylitol gum- and mastic chewing on the remineralization rate of caries-like lesions. J. Dentistry, 6 (1): 6-10.

91. Sakagami H., Kishino K., Kobayashi M., Hashimoto K., Iida S., Shimetani A., Nakamura Y., Takahashi K., Ikarashi T., Fukamachi H., Satoh K., Nakashima H., Shimizu T., Takeda K., Watanabe S., Nakamura W. [2009]: Selective antibacterial and apoptosis-modulating activities of mastic. In vivo, 23: 215-224.

92. Al-Mofarji T., Al-Zahid N.R., Al-Hashimy E.H. [2013]: Antibacterial effect of mastic gum on aerobic oral bacteria. Iraqi Nat. J. Nurs. Spec., 26 (2): 136-140.

93. Biria M., Eslami G., Taghipour E., Akbarzadeh Baghban A. [2014]: Effects of three mastic gums on the number of mutans streptococci, lactobacilli and pH of the saliva. J. Dent., 11 (6): 672-679.

94. Lee B.Y., Lee K.H., Kim I.R., Kim Y.H., Park H.R., Park B.S. [2014]: The inhibition of oxidative stress by Chios gum mastic is associated with autophagy. Int. J. Oral Biol., 39 (2): 65-73.

95. Karygianni L, Cecere M, Skaltsounis AL, Argyropoulou A, Hellwig E, Aligiannis N, Wittmer A, Al-Ahmad A. [2014]: High-level antimicrobial efficacy of representative Mediterranean natural plant extracts against oral microorganisms. Biomed Res Int., 839019

96. Makaremi M, Zink K, de Brondeau F. [2016]: The importance of elevated masticatory forces on the stability of maxillary expansion. J Dentofacial Anom Orthod., 50:

97. Koychev S, Dommisch H, Chen H, Pischon N. [2017]: Antimicrobial Effects of Mastic Extract Against Oral and Periodontal Pathogens. J Periodontol., 88: 511-517.