Britney Spears' parenting skills have come under fire once again after it emerged she allegedly tried to have her son's teeth cosmetically whitened. The troubled pop star's mothering skills have previously been subjected to scrutiny after she was filmed nearly dropping baby Sean Preston on a concrete floor and driving with the 22-month-old on her lap. But now the singer has been accused of asking a Los Angeles dentist to cosmetically whiten her son's teeth - only to be refused on health grounds. A source tells Usmagazine.com, "He's having dental problems because Britney just shoves a bottle of juice in his mouth all the time to stop him from crying." "She fed Sean ice cream before bed because the cold would make him sleepy."