+ MODEL

Journal of Dental Sciences (2014) xx, 1e4

Available online at www.sciencedirect.com

ScienceDirect

journal homepage: www.e- jds.com

ORIGINAL ARTICLE

Salivary caries parameters: Comparativestudy among Yemeni khat chewers andnonchewers

Khaled Rashad Al-Alimi a*, Abdul Aziz Abdul Razak a,Roslan Saub b**

a Department of Restorative Dentistry, Faculty of Dentistry, University of Malaya, Kuala Lumpur,Malaysia

b Department of Community Oral Health and Clinical Prevention, Faculty of Dentistry,University of Malaya, Kuala Lumpur, Malaysia

Received 7 February 2014; Final revision received 25 March 2014Available online - - -

KEYWORDSkhat;saliva flow rate;saliva pH;viscosity

* Corresponding author. Department** Corresponding author. DepartmentKuala Lumpur, Malaysia.

E-mail addresses: alalimi_khaled20

Please cite this article in press as: Anonchewers, Journal of Dental Scien

http://dx.doi.org/10.1016/j.jds.2014.01991-7902/Copyrightª 2014, Associatio

Abstract Background/purpose: Millions of people in Yemen and East African countries chewkhat for more than 5 hours daily for its amphetamine-like effects. Previous studies have asso-ciated khat chewing with salivary glands enlargement, inflammation, and xerostomia. Howev-er, no information is available on the possible effects of this habit on salivary parameters. Thiscomparative study aims to evaluate salivary parameters, such as salivary flow rate, pH, andviscosity among Yemeni khat chewers and nonchewers.Materials and methods: Stimulated saliva was collected from 30 Yemeni male khat chewersand 30 nonchewers living in Sana’a City. Salivary flow rate, pH, and viscosity were measured.Data were analyzed using the Mann-Whitney test, an independent t test and the Chi-squaretest.Results: The mean salivary flow rates (mL/minute) among khat chewers and nonchewers were0.71 � 0.07 mL/minute and 0.99 � 0.09 mL/minute, respectively. The independent t testshowed a significant difference in salivary flow rate between the two groups at (P < 0.05).The mean pH values among khat chewers and nonchewers were 6.32 � 0.44 and6.78 � 0.35, respectively. The Mann-Whitney test showed that khat chewers have significantlylower salivary pH compared to nonchewers at (P < 0.05). The salivary viscosity of khat chewersand nonchewers also differed significantly at (P < 0.05).

of Restorative Dentistry, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.of Community Oral Health & Clinical Prevention, Faculty of Dentistry, University of Malaya, 50603

05@yahoo.com (K.R. Al-Alimi), roslans@um.edu.my (R. Saub).

l-Alimi KR, et al., Salivary caries parameters: Comparative study among Yemeni khat chewers andces (2014), http://dx.doi.org/10.1016/j.jds.2014.04.003

4.003n for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.

2 K.R. Al-Alimi et al

+ MODEL

Please cite this article in press as: Anonchewers, Journal of Dental Scien

Conclusion: The findings suggest that khat-chewing habits may reduce salivary flow rate, lowersalivary pH, and lead to unhealthy viscosity.Copyright ª 2014, Association for Dental Sciences of the Republic of China. Published by Else-vier Taiwan LLC. All rights reserved.

Introduction

The khat plant (Catha edulis) is widely cultivated in certainareas of East Africa and the Arabian Peninsula, particularlyin Yemen. Several million people from these regions arehabitual khat chewers. The main effects of continuouslychewing khat for more than 5 hours daily, such as during asocial-cultural meeting, are moderate euphoria and exci-tation,1 owing to the amphetamine-like effect of this plant.This effect is mainly attributed to the alkaloid cathinone,which can be considered “a natural amphetamine”.2

Khat leaves are usually kept in the lower distal buccalfold of the mouth. Chewing khat has been linked to gingi-vitis, periodontal pocket formation, gingival recession,dental caries, and tooth mobility.3 Previous studies haveassociated khat chewing with salivary enlargement,inflammation, and xerostomia.3e5

Saliva helps to maintain the balance in the oral flora topromote the health and integrity of tooth surfaces.6e8

Saliva protects the teeth against caries with mechanismsincluding bacterial clearance, direct antibacterial activity,buffering, and remineralization. In general, saliva lubri-cates the oral cavity, keeps microorganisms and food debrisoff the tissues and teeth, and helps in balancing thedemineralization and remineralization process on the toothsurface.9e12

An insufficient salivary flow rate causes an inadequatesalivary buffering action, which results in decreased oralpH. Consequently, the inability of the host to counterbal-ance the acidic environment creates an ideal condition forcariogenic bacteria.13 Saliva has major antibacterial activ-ity through its enzymes that could improve tooth health.14

Several medications, medical circumstances, and radio-therapy to the head and neck of patients cause xerostomia(dry mouth) resulting in rampant caries.14

Guo and Shi15 recently found that saliva contains variousmicrobes and hosts biological components that could beused for caries risk assessment. In addition, the viscosityand capability of saliva to lubricate the oral cavity, washaway microorganisms and food debris, and balance thedemineralization and remineralization process on the oralcavity aid in maintaining oral health.3,10,11

The khat chewing habit may affect the properties ofsaliva and consequently contribute to the formation ofdental caries. However, no information is available on thepossible effects of this habit on salivary parameters. In thisstudy, a comparison of salivary parameters between khatchewers and nonchewers was conducted to provide dentalpractitioners with knowledge on salivary caries parametersthat may affect dental caries management among khatchewers.

l-Alimi KR, et al., Salivary cariesces (2014), http://dx.doi.org/10.

Materials and methods

The study was approved by the research ethics committeeof the University of Malaya number DFRD 1001/0009 (P).This comparative study involved 60 healthy Yemeni malekhat chewers and nonchewers, aged 18e22 years,selected from private dental clinics in Sana’a City. Theparticipants were selected based on their khat chewinghabit. The participants were then divided into two groups,one with 30 khat chewers and the other with 30 non-chewers. An individual was excluded from the study if hehad any special health care needs, was suffering from anysystemic or metabolic diseases, had taken any medicationwithin the last two weeks, or was undergoing orthodontictreatment.

The participants were given written instructionsregarding the collection of saliva. They were asked not toeat, drink, or smoke on the day of saliva collection. Theywere also instructed to swallow several times to cleartheir mouth and stimulate new saliva. Whole saliva wasobtained under basal conditions between 8:00 AM and9:00 AM to minimize changes attributed to circadianrhythm variations. Prior to saliva collection, the partici-pants were asked to rinse their mouth twice with tapwater to remove food debris and other nonsalivary ele-ments that could interfere with the measurements. Allparticipants were subjected to trial before the collec-tion. Saliva was then collected in a plastic cup for5 minutes.

Saliva pH, flow rate, and viscosity measurements

All participants were instructed to sit still prior to salivacollection. They were also instructed to lean their headforward over the funnel, chew gum without swallowingany saliva, and spit every minute into the tube. Allsaliva samples were processed within a 5-minutecollection process. The volume of saliva was measuredusing a 5 mL syringe, and the flow rate was calculated inmL/minute.

All saliva samples were collected and prepared. Thesamples were allowed to reach the same temperature,given that pH readings are temperature dependent. Theadvance pH meter 850056 (Sper Scientific Ltd, Scottsdale,Arizona, USA) was used to measure saliva pH. The pH meterwas calibrated, and the manufacturers’ instructions werefollowed. Viscosity was assessed visually.16 A frothy andbubbly appearance indicates increased viscosity, whereas awatery and clear appearance indicates normal and healthysalivary viscosity.

parameters: Comparative study among Yemeni khat chewers and1016/j.jds.2014.04.003

Khat and salivary caries parameters 3

+ MODEL

Results

Salivary flow rate

Normal flow rate of stimulated saliva was found in 70% ofthe nonchewing group, and the difference was highly sta-tistically significant. Low salivary flow rate was found in100% of the khat chewers group. The mean saliva flow rate/minute for the khat chewer group and nonchewer groupwere 0.71 � 0.07 mL/minute and 0.99 � 0.09 mL/minute,respectively. The independent t test showed a significantdifference in the salivary flow rate/minute between bothgroups at (P < 0.05). Results show that khat chewersexhibited a significantly lower salivary flow rate/minute.

Saliva pH

The mean saliva pH values for the khat chewer group andnonchewer group were 6.32 � 0.44 and 6.78 � 0.35,respectively. Furthermore, pH < 6.30 was found in 50% ofthe khat chewers. The Mann-Whitney test showed a sig-nificant difference in saliva pH between khat chewers andnonchewers at (P < 0.05). This result indicates that khatchewers exhibited significantly lower pH than thenonchewers.

Saliva viscosity

A bubbly appearance of saliva was found in 87% of the khatchewers and in 43% of the nonchewers, as shown in Table 1.A clear appearance of saliva was found in 57% of the non-chewers and 13% of the khat chewers. The Chi-square testshowed a significant difference at (P Z 0.001) as shown inTable 1.

Discussion

This study is the first to attempt to compare salivary pa-rameters, such as flow rate, pH, and viscosity, betweenYemeni khat chewers and nonchewers.

Normal salivary flow rate imparts a strong protectionagainst dental caries. This study found that 80% of khatchewers exhibited a stimulated salivary flow rate at almost0.70 mL/min. A flow rate of <1.0 mL/minute is regarded aslow.17,18 A significantly lower salivary flow rate among khatchewers may be associated with some predisposing factors,such as salivary gland fatigue attributed to chewing forseveral hours daily, lack of stimulus to the salivary gland,or a problem with the salivary gland itself. Al-Sharabi3

added that a positive association exists between khatchewing and salivary gland enlargement and inflammation.

Table 1 Saliva viscosity among khat chewers andnonchewers.

Group n Viscosity appearance P (Chi-square test)

Bubbly Clear

Khat chewers 30 26 (87%) 4 (13%) 0.001Nonchewers 30 13 (43%) 17 (57%)

Please cite this article in press as: Al-Alimi KR, et al., Salivary cariesnonchewers, Journal of Dental Sciences (2014), http://dx.doi.org/10.

A patient with a stimulated salivary flow rate of less than1.0 mL/minute is at risk of developing dental caries.19

In this study, khat chewers exhibited an inadequate orlow salivary flow rate. The clinical findings can be attrib-uted to the amphetamine-like effect of khat. Amphetamineusers are known to have rampant caries due to reducedsalivary flow.20 As a result, the lack or inadequacy of sali-vary flow increases the rate of caries progression.21 Al-Sharabi3 also indicated an increase in cervical caries,attrition, and staining, which may be associated with lowsalivary flow rate among khat chewers. Similar to thefindings of this study, Yarom et al.5 reported that oraldryness occurs 30 minutes upon initiation of a khat-chewingsession. Stimulating the flow of saliva alters its composi-tion. Dawes22 noted that increasing the rate of salivary flowincreases the concentration of protein, sodium, chloride,and bicarbonate while decreasing the concentration ofmagnesium and phosphorus. Perhaps of the greatestimportance is the increase in the concentration of bicar-bonate, which increases progressively with the duration ofstimulation. The increased concentration of bicarbonatediffuses plaque, neutralizes plaque acids, increases pH ofthe plaque and favors the remineralization of damagedenamel and dentin.

In this study, the pH was significantly lower among khatchewers than nonchewers. Saliva serves an importantfunction in optimal oral health, and new research suggeststhat salivary pH is more critical to the development andprogression of dental caries than once thought.23 Sciencesuggests that pH, rather than sugar, is the selective factorfor cariogenic plaque biofilms. Low saliva pH is associatedwith reduced salivary flow and increased risk for caries.23

This study indicates that salivary viscosity of khatchewers is bubbly, which is unhealthy. Almost 90% of khatchewers have bubbly and thick saliva, whereas only 40% ofthe nonchewers exhibited this characteristic. Bubbly andthick saliva is unhealthy and is not watery owing to inade-quate salivary flow rate. Salivary viscosity affects the co-aggregation of oral streptococci with Actinomyces. An in-crease in salivary viscosity is disadvantageous to oral healthin terms of bacterial clearance from the oral cavity.24

Increased salivary viscosity may also be associated withan increase in dental caries.25 In addition, salivary viscosityis significantly influenced by pH and calcium.

The time of saliva collection was between 8:00 AM and9:00 AM to prevent circadian rhythm variation. The partici-pants fasted for 1 hour before saliva collection to avoid theeffect of immediate food consumption and food contami-nation. The limitation of this study is that unstimulatedsaliva and buffering capacity were not measured. The flowrate may vary between stimulated and unstimulated saliva.However, no significant difference in salivary flow rate forstimulated and unstimulated saliva was reported by Heftand Baum.26 Moreover, in this study, salivary parameterswere measured only on one occasion. It has been found thatsalivary flow rate varied from time to time.27

Within the limitations of this study, we can thus concludethat khat chewing may affect salivary parameters or prop-erties such as flow rate, pH, and viscosity. Further consid-eration and studies are needed to investigate the relationbetween khat chewing and such findings. Further consider-ation recommended investigating which active components

parameters: Comparative study among Yemeni khat chewers and1016/j.jds.2014.04.003

4 K.R. Al-Alimi et al

+ MODEL

in khatmay affect the saliva among khat chewers. Additionalresearch is recommended to study the correlation amongsalivary pH, stimulated and unstimulated salivary flow rate,buffering capacity, consistency, and the presence ofS. mutans presence relative to khat chewing.

Conflicts of interest

All authors declare no conflicts of interest.

References

1. Kalix P. Khat: scientific knowledge and policy issues. Br JAddict 1987;82:47e53.

2. Kalix P. Catha edulis, a plant that has amphetamine effects.Pharm World Sci 1996;18:69e73.

3. Al-Sharabi AK. Oral and Paraoral Lesion Caused by Qat Chew-ing. PhD Thesis. Sudan: University of Khartoum Faculty ofDentistry, 2002.

4. Kennedy, JG. The Flower of Paradise: The InstitutionalizedUse of the Drug Qat in North Yemen (vol. 10). Springer, 1987.

5. Yarom N, Epstein J, Levi H, et al. Oral manifestations ofhabitual khat chewing: a case-control study. Oral Surg OralMed Oral Pathol Oral Radiol Endod 2010;109:60e6.

6. Hicks J, Garcia-Godoy F, Flaitz C. Biological factors in dentalcaries: role of saliva and dental plaque in the dynamic processof demineralization and remineralization (part 1). J ClinPediatr Dent 2004;28:47e52.

7. Garcıa-Godoy F, Hicks MJ. Maintaining the integrity of theenamel surface: the role of dental biofilm, saliva and preven-tive agents in enamel demineralization and remineralization. JAm Dent Assoc 2008;139(Suppl. 2):S25e34.

8. Kutsch VK, Young DA. New directions in the etiology of dentalcaries disease. J Calif Dent Assoc 2011;39:716e21.

9. Dowd FJ. Saliva and dental caries. Dent Clin North Am 1999;43:579e97.

10. Stookey GK. The effect of saliva on dental caries. J Am DentAssoc 2008;139(Suppl. 2):S7e11.

11. Hara AT, Zero DT. The caries environment: saliva, pellicle,diet, and hard tissue ultrastructure. Dent Clin North Am 2010;54:455e67.

Please cite this article in press as: Al-Alimi KR, et al., Salivary cariesnonchewers, Journal of Dental Sciences (2014), http://dx.doi.org/10.

12. Paice EM, Vowles RW, West NX, et al. The erosive effects ofsaliva following chewing gum on enamel and dentine: anex vivo study. Braz Dent J 2011;210:E3.

13. Simmonds R, Tompkins G, George R. Dental caries and themicrobial ecology of dental plaque: a review of recent ad-vances. N Z Dent J 2000;96:44e9.

14. Spielmann N, Wong DT. Saliva: diagnostics and therapeuticperspectives. Oral Dis 2011;17:345e54.

15. Guo L, Shi W. Salivary biomarkers for caries risk assessment. JCalif Dent Assoc 2013;41:107e9.

16. Ranganath L, Shet R, Rajesh A. Saliva: a powerful diagnostictool for minimal intervention dentistry. J Contemp Dent Pract2012;13:240e5.

17. Ericsson Y, Hardwick L. Individual diagnosis, prognosis andcounselling for caries prevention. Caries Res 1978;12(Suppl. 1):S94e102.

18. Nauntofte B, Tenevuo JO, Lagerlof F. Secretion and composi-tion of saliva. In: Fejerskov O, Kidd E, eds. Dental Caries. TheDisease and its Clinical Management, 2nd ed. Oxford: Black-well Munksgard, 2003:7e29.

19. Dawes C. Physiological factors affecting salivary flow rate, oralsugar clearance, and the sensation of dry mouth in man. J DentRes 1987;66:648e53.

20. Klasser GD, Epstein J. Methamphetamine and its impact ondental care. J Can Dent Assoc 2005;71:759e62.

21. Garg AK, Malo M. Manifestations and treatment of xerostomiaand associated oral effects secondary to head and neck radi-ation therapy. J Am Dent Assoc 1997;128:1128e33.

22. Dawes C. How much saliva is enough for avoidance of xero-stomia? Caries Res 2004;38:236e40.

23. Heintze U, Birkhed D, Bjorn H. Secretion rate and buffer effectof resting and stimulated whole saliva as a function of age andsex. Swed Dent J 1983;7:227e38.

24. Kitada K, Oho T. Effect of saliva viscosity on the co-aggregationbetween oral streptococci and Actinomyces naeslundii. Ger-odontology 2012;29:981e7.

25. Nordbo H, Darwish S, Bahatnagar RS. Rate of viscosity changesin five salivary protein fractions following pH alterations. Eur JOral Sci 1984;92:302e5.

26. Heft M, Baum B. Basic biological sciences unstimulated andstimulated parotid salivary flow rate in individuals of differentages. J Dent Res 1984;63:1182e5.

27. Sreebny L. Recognition and treatment of salivary inducedconditions. Int Dent J 1989;39:197e204.

parameters: Comparative study among Yemeni khat chewers and1016/j.jds.2014.04.003