Biotribological properties of xerostomia patient saliva and its enhancement

¹ University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Groningen, The Netherlands
² University of Groningen and University Medical Center Groningen, Department of Radiation Oncology, Groningen, The Netherlands
³ University of Groningen and University Medical Center Groningen, Department of Rheumatology and Clinical Immunology, Groningen, The Netherlands
⁴ Academic Centre for Dentistry Amsterdam, Free University and University of Amsterdam, Department of Oral Biochemistry, Amsterdam, The Netherlands
⁵ University of Groningen and University Medical Center Groningen, Department of Oral and Maxillofacial Surgery, Groningen, The Netherlands

^* Corresponding author: p.k.sharma@umcg.nl

Abstract

The study aimed to quantify the lubricating properties of chewing stimulated whole saliva from healthy controls (n=22), from patients suffering from primary Sjögren’s syndrome (n=37) and from patients undergoing head-and-neck radiotherapy (n=34). Materials and Methods All participants had to complete the Xerostomia Inventory questionnaire to score dry mouth sensation. Lubrication was measured using an ex vivo tongue-enamel friction system in terms of Relief and Relief period. MUC5b and total protein concentrations of the saliva samples were measured by an enzyme-linked immunosorbent assay and a bicinchoninic acid assay, respectively. Results Relief of Sjögren’s patients saliva and post-irradiation patients saliva was similar compared with healthy controls, but saliva from post-irradiation patients lubricated significantly better than saliva from Sjögren’s patients. The Relief period was similar between the three groups. The Relief and Relief period were higher for saliva samples post-irradiation compared to pre-irradiation. MUC5b and total protein concentrations were comparable in all groups. MUC5b and total protein output were significantly lower in patients subjected to radiotherapy compared to saliva from healthy controls and pre-irradiation patients. MUC5b concentrations positively correlated with lubricating properties of post-irradiation patient saliva. Conclusions The lubricating properties of patient saliva were not any worse than healthy controls. Lower flow rate leads to lower availability of saliva in the oral cavity and decreases the overall output of protein and MUC5b, which might result in an insufficient replenishing of the mucosal salivary film. Clinical Relevance An insufficient replenishing might underlie the sensation of a dry mouth and loss of oral function. In the talk I will explain biomaterials related strategies, yet ex vivo, to enhance salivary lubrication despite of low flowrates.