( ( While ( saliva ( serves ( as ( ( a lubricant ) ( that ( facilitates ( the ( digestive process ) ) ) ) ) ) ) ) ) ( , ( it ( also ( ( ( ( provides protection ) ( to ( ( teeth and ) ( soft tissue ) ) ) ) ( from ( ( a variety ) ( of ( ( bacteria and ) viruses ) ) ) ) ) . ) ) ) ) )
(ROOT (S (SBAR (IN While) (S (NP (NN saliva)) (VP (VBZ serves) (PP (IN as) (NP (NP (DT a) (NN lubricant)) (SBAR (WHNP (WDT that)) (S (VP (VBZ facilitates) (NP (DT the) (JJ digestive) (NN process)))))))))) (, ,) (NP (PRP it)) (ADVP (RB also)) (VP (VBZ provides) (NP (NN protection)) (PP (TO to) (NP (NP (NNS teeth)) (CC and) (NP (JJ soft) (NN tissue)))) (PP (IN from) (NP (NP (DT a) (NN variety)) (PP (IN of) (NP (NNS bacteria) (CC and) (NNS viruses)))))) (. .)))
While saliva serves as a lubricant that facilitates the digestive process, it also provides protection to teeth and soft tissue from a variety of bacteria and viruses.
(ROOT (S (NP (NNP Saliva) (NNP secretion)) (VP (VBZ initiates) (NP (NN chemical) (NN digestion)) (PP (IN while) (S (ADVP (RB also)) (VP (VBG protecting) (NP (DT the) (JJ oral) (NN cavity)))))) (. .)))