Salivary changes before and after a hematopoietic stem cell transplantation: a systematic review.

Severe oral problems including oral mucositis (OM) and xerostomia often occur after conditioning therapy for hematopoietic stem cell transplantation (HSCT). Saliva plays a major role in protecting the oral mucosa and teeth. Alterations in salivary flow rate or salivary components resulting in decreased salivary defence mechanisms may affect oral/mucosal health and may influence the severity of OM. To assess current scientific knowledge on changes in salivary function and composition before and after HSCT a systematic review was conducted. All English or Dutch articles examining salivary flow rate or salivary components before and after HSCT were included after title/abstract selection by 2 independent reviewers (weighted kappa: 0.91). After quality assessment and exclusion of all research groups with both children < 14 years of age and adults, 33 articles were included for data analysis. Overall, the salivary flow rate was decreased several days and months after HSCT. Although several salivary components were studied, most components were only examined in one or two studies with different patient populations or different time points after HSCT. Seven days after HSCT, albumin and pro-inflammatory cytokines were increased, whereas secretory IgA and components of the salivary antioxidant system were decreased. One month after HSCT, secretory IgA levels were still reduced, but were returned to pre-HSCT values 6 months after HSCT. Six months after HSCT, lactoferrin, secretory leukocyte protease inhibitor and β2 -microglobulin were increased. In conclusion, changes in saliva reflect an inflammatory response directly after HSCT followed by an increased salivary antimicrobial defence 6 months after HSCT.