Why use 有 in 只要前排的牙齿有脱落... about shark teeth? This text is talking about sharks.

很多鲨鱼口中都有成排的利齿。 只要前排的牙齿有脱落，后方的牙齿便会补上，而且新牙齿更大、更耐用。
脱落： 脱掉;落下

只要前排的牙齿有脱落， Why not just write '只要前排的牙齿脱落，'?
Is this supposed to be some kind of Chinese Past Perfect Tense 'have fallen out'? Has the author been reading too much English?
Edit: I hear that in Chinese people might say:
你去过上海吗？ 或者 你有去过上海吗？
你吃过苹果吗？ 或者 你有吃过苹果吗？
What is this use of 有？ Something else omitted? '的经验‘ maybe？？
"前排的牙齿脱落" means "the entire front row of teeth drops off"
前排的牙齿有脱落 is short for "前排的牙齿有脱落(的部分)" which
means "the front row of teeth has dropped off (parts)" 


脱落 in the second sentence is in effect a noun for "脱落(的部分)" - "dropped off (parts)"

If you don't want "前排的牙齿" to imply it is "the entire front row of teeth "  it  has to be changed to "前排有牙齿" (the front row has some teeth)

Unlike in English, Chinese language doesn't use verb tenses. For example, both 'is' and 'was'  is written as '是' in Chinese.