Needham officials have recently stopped adding fluoride to the water because of a nationwide shortage of the substance, said William Wanberg, the town’s water treatment manager. Needham is searching for another fluoride supplier because its original supplier – LCI Ltd. – could not fulfill the town’s needs, he said. The town’s water, which usually has an average fluoride concentration of about 1 part per million, “is getting virtually no fluoride,” Wanberg said. He expects to receive the next shipment of the compound, which is added to water supplies to combat tooth decay, in January.