B  

Epidemiologic follow-up studies show that canines are the teeth least often lost to periodontal breakdown, while lower premolars also rank among the least affected; hence the combination “lower premolar and upper canine” is the least involved in periodontitis compared with other tooth groups [Wood et al., 1989, PMID 2677303; Dosumu et al., 2003, PMID 15259918].