Efficacy of gel-based artificial saliva on Candida colonization and saliva properties in xerostomic post-radiotherapy head and neck cancer patients: a randomized controlled trial

Abstract

Objective: To evaluate the efficacy of an edible artificial saliva gel, oral moisturizing jelly (OMJ), and a topical commercial gel (GC dry mouth gel) on Candida colonization and saliva properties.

Materials and methods: This study was a secondary analysis of a single-blinded randomized controlled trial conducted in xerostomic post-radiotherapy head and neck cancer patients. Candida colonization, stimulated salivary flow rate (SSFR), saliva pH, and buffering capacity (BC) were measured at 0, 1, and 2 months after each intervention. Candida colonization was quantified by colony counts and species identified by Candida Chromagar, polymerase chain reaction, and API 20C AUX system. Statistical significance level was 0.05.

Results: A total of 56 participants in OMJ (N = 30) and GC (N = 26) groups completed the study. OMJ significantly increased saliva pH (p = 0.042) and BC (p = 0.013) after 1-month use, while GC only improved saliva pH (p = 0.027). Both interventions tended to increase SSFR but only GC had a significant increase at 2 months (p = 0.015). GC and OMJ significantly decreased the number of Candida species at 1 and 2 months, respectively. Both groups tended to reduce Candida counts but not significant.

Conclusions: Both OMJ and GC saliva gels could improve saliva pH and decrease the number of Candida species. OMJ is superior to GC in its buffering capacity, while GC may better improve salivary flow rate. Long-term and large-scale study is warranted to test the efficacy of artificial saliva in oral health improvement.

Clinical relevance: OMJ and GC gel could decrease the number of Candida species and improve saliva properties in post-radiation xerostomic patients.

Trial registration number: Clinicaltrials.gov NCT03035825. Date of registration: 25th January 2017.

Keywords: Artificial saliva; Buffering capacity; Candida; Head and neck cancer; Radiotherapy; Xerostomia.

Conflict of interest statement

DT and AL have received a research grant from Dental Innovation Foundation under Royal Patronage. Other authors declare that they have no conflict of interest.

Figures

Fig. 1

Participants’ flow chart of the randomized controlled study. Number of participants enrolled, dropped out, and included for data analysis are shown

Fig. 2

Effect of artificial saliva on stimulated salivary flow rates. Box plot represents median and interquartile (IQ) range of salivary flow rates of participants in the OMJ and GC groups at baseline and after 1 and 2 months of interventions. Whiskers indicate the highest and lowest values no greater than 1.5 times the IQ range. Open circles and triangles represent outliers (values between 1.5 and 3 times the IQ range) and extremes (values more than 3 times the IQ range), respectively. Asterisk (*) indicated a p value of < 0.05 by using related samples Friedman’s test with Bonferroni correction for multiple comparisons.

Fig. 3

Effect of artificial saliva on saliva pH (a) and buffering capacity (b–d). Average saliva pH (a) and buffering capacity (pH after the addition of HCl) (b) of participants in OMJ and GC groups at baseline and after 1 and 2 months of interventions. Asterisk (*) indicates p value < 0.05 by using repeated measure ANOVA with Bonferroni correction for multiple comparisons. Dotted line represents the levels of neutral pH (a) and moderate buffering capacity (b). Comparison of changes in buffering capacity between OMJ and GC groups after 1 and 2 months of interventions (c, d). Stacked bars (c) represent percentage of participants with the same, improved, or worse buffering capacity as compared with their own baseline. Stacked bars (d) represent percentage of participants with low, moderate, and high buffering capacity at each time point. Asterisk (*) indicates p value < 0.05 by using Fisher’s exact test

Fig. 4

Effect of artificial saliva on the quantity of Candida colonization in Candida carriers. Average logCFU (a) of Candida colonization in OMJ and GC groups at baseline and after 1 and 2 months of interventions. Stacked bars (b) represent percentage of Candida carriers with the same, increased, or decreased logCFU as compared with their own baseline

Fig. 5

Effects of artificial saliva on the number of Candida species in Candida carriers. Stacked bar represents a percentage of participants with no Candida colonization (0 species) or colonized with 1, 2, 3, and 4 Candida species in OMJ and GC groups at 0, 1, and 2 months of interventions, and b percentage of participants with the increased, same, or decreased number of Candida species as compared with their own baseline in OMJ and GC groups at 1 month and 2 months of intervention. Asterisk, double asterisk, triple asterisk, and quadruple asterisk represent p value < 0.05, 0.01, 0.001, and 0.0001, respectively, obtained from Chi-square test

Fig. 6

Effects of artificial saliva on Candida species. The prevalence of various Candida species detected in OMJ and GC groups at baseline and after 1 and 2 months of interventions is shown

Fig. 7

Relationship of saliva properties and quantity of Candida colonization after artificial saliva use. Dot plot demonstrated correlation between Candida logCFU and salivary flow rate (a), Candida logCFU and saliva pH (b), and saliva pH and salivary flow rate (c) of Candida carriers at baseline and 1 and 2 months after intervention. r and a p value analyzed by Pearson correlation analysis shown in each plot. Gray-shaded box indicated a p value < 0.05