Award Date

May 2019

Degree Type


Degree Name

Master of Science (MS)


Dental Medicine

First Committee Member

Karl Kingsley

Second Committee Member

Brian Chrzan

Third Committee Member

Tanya Al-Talib

Fourth Committee Member

Jennifer Pharr

Number of Pages



Changes to the oral microflora occur when there are shifts in the levels of the numerous bacterial species. Changes in bacterial load occur in health, disease, and dental treatments such as orthodontics and can be detected through saliva. Many studies dealing with saliva have centered around detecting bacteria known for correlation with chronic periodontitis and caries. Fewer have focused on bacterial species that contribute to microbial shifts not strictly correlated with disease. Measuring the degree of disease progression or future susceptibility is not always possible with traditional clinical parameters alone.

Aggregatibacter actinomycetemcomitans (AA) is a bacterial strain that serves as a bridging species among the oral microbiome. Although it is commonly associated with localized aggressive periodontitis, it is also found commonly in the oral flora not suffering from that severe periodontal condition. AA plays an important role within the oral microbiome as it acts as a bridging species that allows other species of bacteria to coaggregate around it.

Altered tooth surfaces in the oral cavity, such as when fixed orthodontic appliances are in place, introduces surface area for plaque accumulation and impediments to daily plaque removal from the teeth while reducing the efficiency of natural plaque-removal mechanisms, such as salivary flow accompanied by movement of the oral mucosa and tongue. Although, some evidence exists about using unstimulated saliva as a screening tool for overtly putative species, limited evidence suggests screening for bacterial burden of bacterial species such as AA, which precede and contribute to coaggregation and heterotypic community formation.

The data from the following two studies provide evidence that salivary screening of orthodontic patients may be a non-invasive means to detect changes to important periodontal pathogens such as Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum. both adult and pediatric orthodontic patients have an increased prevalence of AA, compared adult and pediatric patients not currently in fixed orthodontic appliances. Additionally, the data clearly suggest a correlation between overall microbial oral burden and Aggregatibacter presence in orthodontic patients. Directionality of the relationship, that is whether unidirectional or bidirectional, is yet to be established. More detailed longitudinal studies on this topic could elucidate this relationship. These data provide strong evidence that more research is needed and that continued focus in this area may provide clinical guidelines for assessment of risk for patients undergoing orthodontic treatment.


Aggregatibacter actinomycetemcomitans; Fusobacterium nucleatum; Microbial prevalence; Orthodontic treatment; Saliva screening


Dentistry | Microbiology

File Format


Degree Grantor

University of Nevada, Las Vegas




IN COPYRIGHT. For more information about this rights statement, please visit