(b)(6) 2012, consumer states that she had been using the product for about 3 weeks and a little piece of her tooth became loose and fell off. Consumer claims that she thinks the piece of tooth fell off because her teeth are older and fragile. Consumer states that the dentist put a filling in. Consumer was issued a refund for the product. Product was requested to be returned for evaluation. (b)(4) 2012, unit received for evaluation. (b)(4) 2012, failure analysis completed. Unit received in moderately used condition. Upon microscopic examination, the nozzle tip appears smooth with only minor irregularities from normal usage. Unit passes functional specifications and the nozzle appears normal. Root cause of customer complaint unknown.