The effects of blindfolding and blindness on the unstimulated and chewing-gum-stimulated flow rates of whole saliva

Abstract

In the early 1970s, Shannon and his colleagues reported that blindfolding caused a reduction in the flow rate of unstimulated and stimulated parotid and submandibular saliva. A study in three parts was now made to investigate the effects of blindfolding or blindness on the flow rate of whole saliva. For the first study, unstimulated whole saliva (UWS) was collected for 5 min from 34 individuals and then eight samples of chewing-gum-stimulated whole saliva (SWS) over a 20-min period. This was carried out on four separate occasions, on two of which, in random order, the individuals collected the saliva immediately after being blindfolded. For the second study, 33 of the individuals repeated the saliva collection protocol on two occasions, with and without blindfolding, but with an accommodation period of 20 min after blindfolding before beginning collection of UWS and with only three samples of SWS being collected over a 4-min period. The flow rate of UWS while blindfolded was significantly ( p < 0.0001) reduced (to 64 and 71% of the flow rate while sighted, in the first and second studies, respectively), as was the flow rate of SWS (to 81–86%, p < 0.0001; and 91–95%, p = 0.0014, respectively). For the third study, UWS and SWS were collected from 24 blind individuals, ranging in age from 13–73 years, and from 24 age- and gender-matched controls. The flow rates of UWS and SWS were not significantly different in the blind participants and controls. DMFT values were 11.1 ± 1.4 and 12.3 ± 1.5 (mean ± SE) in the blind and the controls, respectively, and these values were not significantly different. Thus this study provides no evidence that blind people have lower salivary flow rates or are more susceptible to dental caries than are people with normal sight.