A promising dental care herb mainly against cariogenic bacteria

: Oral diseases are considered from the major health problems and are not limited to dental caries and periodontal diseases but to various autoimmune conditions. Itsayurvedic therapy includes different plants used in management of toothache, sore throat, mouth sores, abscess, broken tooth and jaw, tooth sensitivity, mouth thrush, dental caries, gingivitis, tooth bleaching, dental anxiety, dental phobia and plants used for dental extraction. Peppermint ( Menthapiperita L.), a sterile hybrid of the species M. aquatica L. and M. spicata , L. is considered one of the important aromatic herbs containing high amount of volatile oil used in dental care. The peppermint leaves have a characteristic, aromatic, strong odor and an aromatic, warm, pungent taste followed by a cooling sensation.The medicinal parts are the essential oil extracted from the aerial parts of the flowering plant, the dried leaves, the fresh flowering plant and the whole plant. M. piperita L.is a perennial 50–90 cm high, normally quadrangular and a prototypical member of the mint family. The essential oil of M.piperita L.leaves is characterized by the presence of high percent of menthol (29-48%) in addition tomenthone (20-31%), and the different isomers of menthol in addition to other constituents. M. piperita L. is one of most promising species with antibacterial potential against cariogenic bacteria as Streptococcus mutans . Peppermint oil and leaves posses several other biological effects as antiseptic in oral preparations, antibacterial,antiviral, antifungal, antioxidant and antispasmodic effects. It is also used as a flavoringagent in food and pharmaceutical industry and oral preparations.


INTRODUCTION
Recently there is a great renewed interest for the reuse of differenttraditional drugs generally in therapy and especiallyfor oral and dental health.Various plants have high potential in the treatment of dental problems. The most commonly used medication for oral and dental health is Mentha piperitaL..Mentha piperita L., a medicinally important plant belongs to the Family Lamiaceae(African pharmacopoeia 1985) and commonly known as Peppermint is a hybrid of M. spicata L. (spearmint) and Mentha aquaticL.. It was cultivated by the ancient Egyptians and documented in the Icelandic pharmacopoeia of the thirteenth century. It is widely grown in temperate areas of the world, particularly in Europe, North America and North Africa but nowadays cultivated throughout all regions of the world. The medicinal parts are the essential oil extracted from the aerial parts of the flowering plant, the dried leaves, the fresh flowering plant and the whole plant. Peppermint oil has a fresh, sharp, menthol smell, is clear to pale yellow in color and watery in viscosity. India is the world's largest producer and exporter of mint oil(Balakrishnan 2015).It is used in the form of herbal preparation(s); infusion and tinctures; in addition to its use in different Pharmaceutical forms whether solid or liquid dosage forms. glandular head containing the essential oil.Calcium oxalate crystals absent(Mentha piperita folium -WHO Herbal Monograph 2011).

Pesticide residues
The recommended maximum limit of aldrin and dieldrin is not more than 0.05mg/kg (European pharmacopoeia 1996)and the WHO guidelines on quality control methods for medicinal plants (WHO 1998) and pesticide residues (WHO 1998). Heavy metals For maximum limits and analysis of heavy metals, consult the WHO guidelines on quality control methods for medicinal plants (WHO 1998).

Radioactive residues
Where applicable, consult the WHO guidelines on quality control methods for medicinal plants (WHO 1998) for the analysis of radioactive isotopes.
M. piperitaL. is used in making oral dentifrices as it can provide overall freshness in breath and also keep away bad breath(Balakrishnan 2015). Mentha is used in preparations used as mouthwashes to remove dental plaque (Bhat N. 2013)(Henley-Smith C.J. 2013). The aqueous extract of Mentha piperita (linn.) has inhibited the initiation and promotion of oral dysplastic lesions(Kasem R.F. 2014)and for treatment of inflammation of the oral mucosa(Brahmi F. 2017).

Anti-bacterial effect against cariogenic bacteria:
The oral cavity contains a wide variety of oral bacteria, but only a few specific species of bacteria are believed to cause dental caries namely Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus, Nocardia spp. Streptococcus mutans are most closely associated with caries (Kabra P. 2012).The essential oil of M. piperitaL. has strong antibacterial activity against S. mutans and lactobacilli responsible for dental caries( M. piperitahas been proved to have antimicrobial activity against oral microorganisms and can be used as an alternative medicine and as an adjunct to the conventional therapy, which would help the countries which are developing and having financial constraints and with limited oral health care facility for the concerned population(Raghavan R. 2018).Menthol is also used as a mouthwash which is effective as an anti-plaque and anti-gingivitis agent(Ali N.A. 2015).
Traditional Uses -Peppermint has traditionally been used as a rubefacient(Hawthorn M 1988).
-The essential oil from Mentha is used topically to treat oral mucosal inflammation and also an antimicrobial and an ingredient in many analgesic creams. Approved for internal use, the oil from Mentha is also used to treat bile duct discomfort, irritable bowel syndrome, myalgia and neuralgia, inflammation of the oral mucosa, discomfort from menstrual cramps, secondary amenorrhea and oligomenorrhea, and diverticulitis and is used as an anti-inflammatory and expectorant(Fatiha Brahmi 2017). -In India, Peppermint oil (as well as peppermint leaf) has been used internally as an antispasmodic (upper gastrointestinal tract and bile ducts) and to treat irritable bowel syndrome, catarrh of the respiratory tract, and inflammation of the oral mucosa. Externally, peppermint oil has been used for myalgia and neuralgia, to relieve menstrual cramps and used externally for neuralgia, myalgia, headaches, migraines, and chicken pox. In addition, Peppermint plants have been used for many conditions, including loss of appetite, common cold, bronchitis, sinusitis, fever, nausea, vomiting, and indigestion(Fatiha Brahmi 2017). -Anti-oxidant activity: The oil and different extracts of M. piperita exhibit significant antioxidant activity (Singh R.

2015)
-Cardiovascular activity: M. piperitais said to have vasodilating properties on some animals. It has a lowering effect on the heart rate and the systolic pressure. Relaxation of bronchial smooth muscles , increase in the ventilation are also other cardiovascular effects of peppermint oil. (Robbers JE 1999).
-Gastrointestinal Benefits: M. piperitaL. is used for treatment of non-obstructive dyspepsia without any known side effects. It improves the gastric emptying rate. There is a significant antiemetic effect of peppermint in reducing postoperative nausea for patients with very sensitive gag reflexes(Balakrishnan 2015).

-Neuropsychiatric Effects:
Some studies have suggested that peppermint is a central nervous system stimulant. Studies have been conducted on the effectiveness of aromas on cognitive performance, perceived physical workload, and pain responses were conducted based on possible changes in the brain activity(Balakrishnan 2015).

-Endocrine Effects:
Certain researches have proved that there was a statistically significant increase in the secretion of endocrine hormones(Robbers JE 1999). In one study there was a noted segmental maturation arrest in the somniferous tubules however, the effects of M.spicataL. extended from maturation arrest to diffuse germ cell aplasia in relation to the dose. Other than this there are not many significantly known effects on the human endocrine system.

-Effect on Skin and Mucous Membrane
M. piperitaL. is said to be a good analgesic to be applied topically and also a coolant for the skin. M. piperitaL. oil stimulates cold receptors on the skin and dilates blood vessels, causing a sensation of coldness and an analgesic effect (Robbers JE 1999). Menthol is a topical vasodilator that enhances the absorption of other topical skin medications. It is said that menthol enhances the absorption of cortisone, mannitol, indomethacin, morphine hydrochloride, and propranolol (El-Kady IA 1993) (Pattnaik S 1997). Menthol moderates oral sensations of warmth and coldness(Moleyar V 1992)(Janssen AM 1986). In low concentrations, topical application of menthol causes a cooling sensation, while in high concentrations it causes irritation and local anesthesia(Raudenbush B 2002). It also increases cutaneous blood flow, muscle temperature, and skin temperature after topical application of the oil. Some studies have claimed that menthol has reduced histamine induced irritation and itching. -

Immune modulation
Menthol has anti-inflammatory effects when applied topically. In one study it was claimed that it could suppress antigen induced allergies. Menthol also has a property of inhibiting cutaneous anaphylaxis that's mediated by IgE antibody (Balakrishnan 2015).
-Anti-spasmodic activity: Previous studies have shown that various kinds of mint were effective in reducing muscle pain (Fox N. 1027)muscle relaxation, and reduce fatigue. Until now, many researches have been done on the effectiveness of various kinds of natural products in the improvement of sport performances. Mint is a herb which is well known for its antispasmodic, painkilling (Eccles R. -Anti-headache activity Since ancient times, herbal therapy has been used as treatment for headache disorders. Consumption of peppermint andderivatives is the best target for headache therapy in combination in relieving patients' headache pain(Loolaie M. 2017).

-Effect on hepatic enzymes
The aqueous extract ofpeppermint (at concentration 2% v/v) can modulate of phase Iand phase II drug metabolizing enzymes. In phase I, a varietyof enzymes act to introduce reactive and polar groups into theirsubstrates. Phase II biotransformation reactions generallyserve as a detoxifying step in drug metabolism.The peppermint alcoholic extract ameliorated theadverse effects of CCl 4 on growth performance and liver function,therefore it was indicated that it might be useful for the preventionof oxidative stress-induced hepatotoxicity (Loolaie M. 2017).

-Radioprotective Effects
The effectiveness of peppermint alcoholic extract against radiation induced morbidity and mortality using the optimum dose of 100 mg/kg for 3 consecutive days. The antioxidant and free radical scavenging activities of leaf extract of peppermint are directly related to its mechanism of radiation protection.Several mechanisms such as antioxidant activity, immune response,and enhanced recovery of bone marrow have been suggested forchemoprevention and radioprotection of peppermint extracts(Loolaie M. 2017).

Other traditional dosing:
The following doses of peppermint havebeen used traditionally for various indications of gastrointestinaltract, gall bladder, and bile duct, and there is no proven dosing regimen(Keifer D.
-Tea:3g of dried peppermint leaves in 250mL of boilingwater, approximately 3-4 cups daily between meals for gastrointestinal symptoms.

Inhalation dosage:
Congestion:Traditionally, 3-4 drops of oil added to hot water andinhaled has been used to relieve congestion. Alternatively, 62.5mgmenthol in 1mL petrolatum has been applied and inhaled in treating nasal congestion (Eccles 1990).

Parenteral dosage
Caution:From one case study, peppermint oil should not be injected, as it may cause pulmonary edema by direct toxicity and anincrease in pulmonary vascular permeability (Behrends 2005).
Caution:Avoid topical use of peppermint oil around the facial orchest areas of infants and young children, especially around thenose, because the menthol constituent can induce apnea, laryngealand bronchial spasm, acute respiratory distress with cyanosis, orrespiratory arrest if applied directly to the nasal and the chest areas(Wyllie 1994).
-The intraperitoneal LD 50 ofpeppermint oil U.S.P. was determined to be 819mg/kg after 24hours (Eickholt 1965). Rats administered peppermint oil and pulegone (a constituent of peppermint oil) up to 100-160mg/kg body weight perday developed brain lesions and encephalopathy after 28 days(Olsen P. and Thorup I. 1984). Pulegone, at doses of 80-160mg for 28 days, induced atonia,weight loss, decreased blood creatinine, and histopathologicalchanges in the liver in an animal study (Thorup 1983). Ataxia and convulsions have occurred in single doses of 3, 4, and 5g/kg of peppermint oil in an animal study (D. 1989). Cyst-like spaces in the whitematter of the cerebellum were observed after 90 days of peppermint oil administration at doses of 10, 40, 100mg/kg body weightper day in an animal study (Thorup 1983) In rats given menthone orally,there was a decrease in creatinine, and increases in alkaline phosphatase, bilirubin, and liver and spleen size (Madsen 1986). The no-effectlevel was < 200 mg menthone per kilogram of body weight per day.In one case study, injection of peppermint oil resulted in pulmonary edema and acute lung injury, presumably due to direct toxicity and a resultant increase in pulmonary vascular permeability (Behrends 2005).

Conclusion
Concerning the importance of Peppermint in the remedy of dental caries, it can be considered as one of the potent and highly safe drugs used for their treatment due to its effective antibacterial activity against cariogenic bacteria. It has a bright future in this field for its great benefits and its safety for use in humans without any considerable side effects or contraindications.