My 34 weeker got teeth the quickest, she got her first at 12 weeks then not another one till 10 months, but then had them all except 1 and 2 year molars by the time she was a year old.
My 36w, 38w and 39w boys all had 1 tooth at 1 year old, and only about 4 teeth by 18 months(well, River isn't 18 months yet!)...Kincaid, 39w, didn't get his last 2 year molar till 4 years 9months old, and Travis, 38w, still has 2 he needs to get at almost 3.
I think some kids are just really slow teethers...I know DH had a lot of teeth at 1 just from pictures, but I didn't get my first tooth till 15 months, so I think it is maybe genetic.
eta: Janelle, the 34weeker, is also missing her 2 year molars entirely, they never formed, still don't show up on x-rays. Which is good, since she also had to have her 6 year molars removed before they came in due to having a really small mouth, so another 4 teeth just wouldn't fit in there at all.