Award Date


Degree Type


Degree Name

Master of Science (MS)


Dental Medicine

First Committee Member

Karl Kingsley

Second Committee Member

Clifford Seran

Third Committee Member

Bernard Hurlbut

Fourth Committee Member

Jennifer R. Pharr

Number of Pages




Many research studies involving orthodontic patients have a natural inclination to focus on changes in levels of cariogenic pathogens after bracket placement, and very few studies examine the role of changes of periodontal pathogens – particularly among adult patients. Interestingly, recent evidence suggests that increased levels of a specific periodontal pathogen, Fusobacterium nucleatum, may elevate risk for development of colon cancer in adults through direct pathways. Based upon this new evidence, the objective of the current study was to screen saliva samples taken from orthodontic patients to determine the prevalence of periodontal pathogens, including F. Nucleatum, T. denticola, and P. gingivalis.


Following an OPRS (human subjects) approved protocol, saliva samples were collected at random from orthodontic and non-orthodontic patients over the course of several weeks. DNA was subsequently isolated from these samples and screened using polymerase chain reaction (PCR) for the presence of Fusobacterium nucleatum, Treponema denticola and Porphyromonas gingivalis, using primers designed specifically to distinguish these micro-organisms.


A total of 310 samples were collected and analyzed. The 159 orthodontic samples revealed lower overall levels of the three oral pathogens tested, compared to the 151 non-orthodontic samples. More specifically, the levels of F. nucleatum, T. denticola, and P. gingivalis were detected in 38.4%, 27.7% and 36.5% of orthodontic patients compared with 39.1%, 35.8%, and 40.4% in non-orthodontic patients respectively.


These findings support previous evidence that a significant proportion of orthodontic clinic patients may harbor periodontal pathogens at high levels. These results are much higher than previous studies which found periodontal pathogens including P. gingivalis in about 39.1% of clinic patients. Although high levels of periodontal pathogens were observed in the orthodontic sample, interestingly, even higher levels were observed in the non-orthodontic sample, when comparing the two. These findings are important when determining oral health changes that adult patients within this population may face during orthodontic treatment. These findings suggest that orthodontic patients could benefit from not only routine dental and periodontal treatment, but also from increased education and awareness regarding the possibility of increased risk for the development of colon cancer among some patients.


Oral Health; Orthodontics; Periodontal Pathogen; Saliva screening


Dentistry | Microbiology | Science and Mathematics Education

File Format


Degree Grantor

University of Nevada, Las Vegas




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