ARTÍCULOS ORIGINALES

Effect of chewing gums on the production of volatile sulfur compounds (VSC) in vivo

 

Cassiano K. Rösing^1,2, Sabrina C. Gomes¹, Diego G. Bassani¹, Rui V. Oppermann²

¹ Lutheran University of Brazil, Brazil.
² Federal University of Rio Grande do Sul, Brazil.

CORRESPONDENCE Cassiano Kuchenbecker Rosing Rua Dr. Valle, 433/701 90560-010 - Porto Alegre - RS - Brasil e-mail: ckrosing@hotmail.com

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ABSTRACT

The aim of the present study was to evaluate the effect of two chewing gums on the production of volatile sulfur-containing compounds (VSC) in vivo. Fourteen periodontally healthy participants (20-35 years old) were included in the test panel. Test gum 1 (TG1) contained sucrose and Test gum 2 (TG2) contained xylitol and zinc citrate. Two series of tests were conducted with a double-blind cross-over design. Following an overnight refrain from oral hygiene, VSC was measured before and at 5, 15, 30, 45 and 60 minutes of chewing the test gums. In the second series, VSC production was monitored prior to and up to 30 minutes after a rinse with cysteine 6mM alone or after a rinse followed by chewing the test gums. For the first test, the results were analyzed by repeated measurements ANOVA for intra-group and paired sample t test for intergroup comparisons. In the second series, percent reduction of VSC was compared by Friedman and Wilcoxon tests (p<.05). The test gums did not differ in terms of VSC production, with values ranging from 146 ppb after 5 minutes to 86 ppb after 60 minutes. Similar reductions in VSC production following cysteine were observed for both test gums, with the largest reductions (71% to 52%) observed after 5 and 15 minutes. It can be concluded that VSC production is diminished after chewing gum and that the use of chewing gums reduces temporarily the VSC production enhanced by cysteine rinses.

Key words: Sulfur; Halitosis; Chewing gum.

RESUMO

Efeito de gomas de mascar na produção de compostos sulfurados voláteis (CSV) in vivo

O objetivo do presente estudo foi avaliar o efeito de duas gomas de mascar na producao de compostos sulfurados volateis (CSV) in vivo. Quatorze participantes periodontalmente saudaveis (20- 35 anos de idade) foram incluidos no estudo. A goma teste 1 (TG1) continha sacarose e a goma teste 2 (TG2) continha xilitol e citrato de zinco. Duas series de testes foram realizadas com um desenho duplo-cego cruzado. Apos a abstencao de higiene oral noturna, CSV foram medidos antes e 5, 15, 30, 45 e 60 minutos apos o ato de mascar as gomas. Na segunda serie, a producao de CSV foi monitorada antes e ate 30 minutos apos um bochecho com cisteina a 6mM isoladamente e quando do ato de mascar as gomas. Para o primeiro teste, os resultados foram analisados atraves de ANOVA de medidas repetidas para comparacoes intragrupo e teste t para amostras pareadas nas comparacoes intergrupo. Na segunda serie, o percentual de reducao de CSV foi comparado pelos testes de Friedman e Wilcoxon (p<.05). As gomas teste nao diferiram na producao de CSV, com valores abrangendo de 146 ppb apos 5 minutos ate 86 ppb apos 60 minu - tos. Reducoes similares na producao de CSV apos bochecho com cisteina foram observadas para ambas as gomas, com as maiores reducoes (71% a 52%) observadas apos 5 e 15 minutos. Pode-se concluir que a producao de CSV e diminuida apos o uso de goma de mascar e que o uso de destas reduz temporariamente a producao de CSV induzida por bochechos com cisteina.

Palavras chave: Compostos sulfurados volateis; Halitose; Goma de mascar.

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INTRODUCTION

Halitosis is known to be mainly related to oral conditions. The production of volatile sulfur-containing compounds (VSC) in the mouth, in particular hydrogen sulfide and methyl mercaptane are the main source of oral malodor¹. These compounds are the end products of microbial degradation of sulfur- containing amino acids from the diet, desquamated epithelial cells, serum and saliva^1,2.
Periodontopathogenic bacteria in periodontal niches as well as in the crypts on the dorsum of the tongue play an important role in the development of halitosis^2,3. The importance of halitosis has led to the formulation of different products that are claimed to have anti-halitosis effect4. Chewing gums have been used at least to minimize halitosis. Due to the easy availability of chewing gum in everyday life, they are used by individuals as a masking agent for the presumed malodor^1,3. The clinical relevance of studying the potential of chewing gums in reducing formation of VSC is linked to their widespread use in the case of malodor. The mechanisms by which chewing gums could have an effect on the production of odoriferous substances include: a) stimulation of saliva, producing  a cleansing effect following the production of VSC; b) if the chewing gum contains sugar, there is a subsequent drop in the mouth pH, reducing the formation of VSC that are generated at neutral or alkaline pH; c) the presence of anti-halitosis substances^1,3,6. The incorporation of different chemical compounds into the chewing gums also seeks to help reduce the production of VSC^5,6. Zinc has been one of the promising chemical substances that may affect the production of VSC, since the presence of zinc in saliva would not allow the volatilization of the odoriferous gases^4,6. Studies have been performed using zinc salts, especially in mouthrinses^1,4,6,7. Also, the use of chewing gums per se have been evaluated in terms of their potential to reduce VSC formation, with promising results⁸.
The aim of the present study was to evaluate the effect of two chewing gums (available on the Brazilian Market and with high rates of consumption) on the production of volatile sulfur-containing compounds (VSC) in vivo.

MATERIAL AND METHODS

Study panel
The participants of this double blind cross-over controlled trial were 14 periodontally healthy individuals, non-smokers, aged 20-35 years, who refrained from oral hygiene on the experimental days, until testing. All volunteers signed an informed consent form and the study protocol was approved by the Committee of Ethical Affairs of the Lutheran University of Brazil.

Test gums
Two chewing gums were tested and were labeled as: TG1: a test chewing gum containing sucrose TG2: a test chewing gum containing xylitol, sorbitol, manitol and zinc citrate.

Collection of Samples
Mouth air samples were collected with the aid of a chairside volatile sulfur compound (VSC) monitor (Halimeter, Interscan, USA). The same monitor was used throughout the experiment, by the same trained examiner. All samples were collected at the same time of the day.

Experimental procedures
Two series of double-blind cross over tests were performed. The first series is shown schematically in Fig.1. Having refrained from oral hygiene in the morning, the volunteers were asked to keep their mouth closed for 90 seconds after which, air samples were collected for VSC measurement. After baseline measurement, the volunteers started to chew the assigned gum and had their VSC content in the mouth monitored 5, 15, 30, 45 and 60 minutes after chewing. This was repeated the next day, with the other gum.

Fig. 1: Experimental design, first series.

The second series of experiments included rinsing with 5 mL of cysteine 6 mM at baseline and monitoring VSC production after 1, 5, 15 and 30 minutes. This constituted the baseline curve. Monitoring was then repeated in the same way after chewing the assigned gum. This was called the test curve. The next day, the same procedures were repeated with the other chewing gum⁹. Fig. 2 illustrates the second series of experiments.

Fig. 2: Experimental design, second series, cysteine-enhancement of VSC production.

Statistical analysis
For the first series of experiments, mean values of VSC production were obtained for baseline, and 5, 15, 30, 45 and 60 minutes after chewing each gum. Overtime comparisons were performed by repeated measurements ANOVA. Intergroup comparisons were performed by paired sample t test. For the second series, mean percent reduction of VSC production as compared to the baseline curve at each time point was obtained and compared overtime by the Friedman test and inter-group by the Wilcoxon test. The individual was the unit of analysis and the α level was set at .05.

RESULTS

The results of the present study are presented in Fig. 3 and 4. Both chewing gums reduced the production of VSC overtime. However, a statistically significant reduction was observed for TG1 already at 5 minutes of chewing, whereas for TG2, a significant difference was observed after 15 minutes. The only statistically significant difference between the test gums was observed at 5 minutes. During all other measurements, mean values of VSC did not differ statistically among the test gums (Fig. 3).

Fig. 3: Mean (s.d.) VSC values (ppb) prior to and up to 60 minutes of chewing.Different letters indicate statistically significant differences overtime for TG1 and TG2 – Multiple comparisons ANOVA – p<.05 and intra-group – paired sample t test – p<.05.

Fig. 4: Mean (s.d.) % reduction of VSC in relation to baseline after chewing over time (VSC enhanced by cysteine rinsing). Different letters indicate statistically significant differences overtime for TG1 (lower case) and TG2 (upper case) - Friedman test - p<.05.
* indicates statistically significant difference between TG1 and TG2, Wilcoxon test - p<.05.

The results of the second series of experiments, with the cysteine enhancement of VSC production are shown in Fig. 4. Comparing the two test gums, TG1 elicited a higher percentage reduction in VSC compared to the baseline curve already at 1 minute after chewing. After the 5-minute assessment, no differences were observed among groups. In the intra-group comparison, the greatest reduction for TG1 was observed at 5 minutes. This effect faded gradually thereon. For TG2, the results after 5 and 15 minutes did not differ. At 30 minutes, the reduction of VSC production was below 20% for both test gums.

DISCUSSION

The present study evaluated the effect of chewing two types of gum on the production of VSC in vivo. It was demonstrated that the act of chewing diminished the production of VSC both naturally and after challenges with cysteine. A double-blind randomized controlled clinical trial with a cross over design was performed. This kind of study design allows for a better comparison, since the individual is its own control, thus minimizing inter-individual characteristics that could account for the results. The trial was double-blind and randomized to avoid potential bias.
VSC measurements were taken with a chairside VSC monitor (Halimeter, Interscan, USA). The same monitor was used throughout the study for a better control of calibration. Individual-linked measurements are commonly extremely variable, increasing the variability of the results, as shown by the large standard deviations. However, the fact that the same individual acts as his/her own control, makes the comparisons more reliable^2,6. The number of individuals included in the present study is similar to other published studies in the international literature^2,4,6,10. The present study comprised 7 males and 7 females. A separate analysis (data not shown) did not reveal differences associated to gender. Thus, the menstrual cycle of the females would not be expected to affect response. Several studies in the literature concerning VSC production include both genders^2,4,6,8,10. Also, each individual was its own control, which tends to diminish bias. Two series of experiments were performed: the first, as indicated in the literature, was performed without VSC production enhancement, and the second was performed by enhancement of VSC by the use of cysteine, as suggested by Kleinberg & Codipilly⁹. In fact, both series of experiments were performed in order to reproduce VSC measurements of individuals with different levels of VSC production. The enhancement with cysteine provides a higher challenge in terms of odoriferous gases in the volunteers^4,9. Two test gums were used in the present study. One of them (TG1) is a regular chewing gum containing sucrose and the other (TG2) contains artificial sweeteners and Zinc Citrate. Zinc salts have been extensively studied in the control of malodor, since, in the presence of water and/or saliva, the sulfurcontaining compounds and the zinc salt dissociate, allowing for the chemical combination of Sulfur and Zinc, not generating the sulfuric gas^4,6.
In both series of experiments, no differences were observed among measurements at baseline, demonstrating that the groups were comparable. In the first series, both gums led to a statistically significant reduction in the VSC measurements overtime. TG1 displayed a statistically significant reduction from 181 to 115 ppb already at 5 minutes, while TG2 reduced VSC measurements only from the 15- minute evaluation to the end of the experiment. The observed reductions were maintained up to 60 minutes of evaluation. In the second experiment, the baseline curve was considered the reference and percent reductions were calculated. The baseline curve peaked at 5 minutes, falling off thereafter. Both tested gums reduced the VSC production in relation to baseline. The same sort of delayed response was observed for TG2 with the cysteine rinsing method, in the sense that at 1 minute, there was already a significant reduction with TG1, but not with TG2, which showed a significant reduction at 5 minutes and thereafter. The clearance of VSC produced by rinsing with cysteine can be interpreted in terms of a slow-down in clearance as VSC production falls⁹. As the effect of cysteine clears, less reduction in VSC is observed. The absence of differences among the tested gums suggests that the act of chewing is more important than the actual components of the product. Moreover, note that TG1 has sugar, which lowers the pH and might affect the production of VSC, whereas TG2 contains zinc citrate, which could also affect the VSC measurements^1,5,6.
The results of the present study are challenging and should alert the dental profession of the potential benefits of using gums in temporary therapeutic approaches to halitosis. In particular, the value of stimulating salivation must be considered when treating oral health problems, including oral malodor. The results of the present study are valid for sugar-containing chewing gums or sugarless chewing gum with zinc. Different formulations should be tested. It can be concluded that the use of the test chewing gums reduces temporarily the natural and the cysteine- enhanced VSC production in vivo.

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