This study sought to screen saliva samples collected from the patient pool at UNLV-SDM to assess the oral microbial burden of two specific oral bacteria related to caries formation (S. mutans or SM) and periodontal disease (P. gingivalis or PG), the major complications and sequelae that result from orthodontic treatment
[1–5]. The results of this study revealed that nearly one quarter (13/56 = 23.3%) of saliva samples had elevated SM levels. A slightly smaller, but significant, percentage of samples (10/56 = 17.8%) were found to harbor elevated levels of PG. Although no demographic differences were found between the SM-positive samples and the overall clinic population, a significant difference was found among the PG-positive samples, which came overwhelmingly from minority patients (9/10 = 90%).
Other research studies have demonstrated elevated PG levels ranging from 5 – 19%, which suggests the results of this study are among the highest yet reported
[3, 11]. More specifically, the finding that a significant percentage (14.3%) of samples had high or very high levels of PG, most of whom were minorities, may suggest that many of these patients had underlying periodontal conditions that might be more readily exacerbated by orthodontic treatment and therapy. In addition, the finding that a similar percentage of samples were found to be at high or very high risk for caries disease (SM > 105 CFU/mL), may suggest a similar, but distinct, percentage of patients may require ancillary treatments, interventions, or additional oral health education in order to complete orthodontic treatment. However, care must be taken when interpreting these results, as there have been no previously established PCR-based assessments of periodontal disease risk corresponding with PG levels, as there are for SM. These data are also consistent with previous studies, which found similar percentages of elevated SM levels ranging from 14 – 40% in both saliva and plaque, which may result in complications involving oral infections and orthodontic treatments interruption
Although patient populations vary from clinic-to-clinic, and from state-to-state, some unique features distinguish the UNLV-SDM patient profile from many other clinics – which may be considered advantageous and beneficial. For example, the gender ratio is much different than the statistical averages in many other local and regional orthodontic clinics
[10–16] – with females accounting for nearly two-thirds (61%) of all clinic patients. Moreover, the percentage of adult patients is much higher (65%) than might otherwise be expected, as is the proportion of minority patients (64%) currently seeking or undergoing orthodontic therapy
[12, 15]. These demographic differences in the composition of the patient population suggest additional research may be warranted in order to provide the most appropriate level of care for the many adult female and minority patients seeking treatment, as their percentages in orthodontic clinics rises. Although some evidence has suggested that adult patients are more likely to have acquired sufficient oral health literacy prior to seeking orthodontic treatment than juveniles or adolescents1, much less evidence exists to assess the oral health status of adult minorities.
While these results provide new information regarding oral health in adult and minority populations, there are several limitations of this study which should also be considered. The most obvious of these issues involves the size and composition of the sample. An analysis of previous orthodontic studies that performed similar saliva screenings for oral pathogens uncovered a range of sample sizes, which varied greatly from a low of only 14 to 70, which suggest that the final sample size of the present study (N = 56) is comparable and well within the range of similar studies
[3, 4, 6, 8, 10, 11, 17, 36–38]. However, the ability of this study to detect log-scale significant differences in CFU/mL between samples, provides strong evidence for sufficient statistical power to make broader inferences, which significantly mitigates any limitations based upon sample size
[23–25]. In addition, the use of relative-endpoint (RE) PCR, the more time-intensive and laborious process of quantitating reaction products for each sample in every cycle used to establish the minimum threshold, exponential phase, and saturation cycles required for calibration and concentration comparisons (the basis of real-time PCR) , to provide quantitative comparative data have been successfully used in many previous studies, which may suggest the RE-PCR method may be particularly appropriate to assess salivary microbial burden when more resource-intensive equipment and facilities for real-time PCR are not available; removing
[26–28] the barriers regarding the difficulty of both isolation and culture of PG, which might otherwise complicate studies examining oral microbial concentrations
However, an additional limitation may be that the sample population of this study consisted solely of adult patients, which does not provide any information regarding the adolescent orthodontic population (<18), although these younger populations have been the focus of intense study in previous research efforts because they have been the more traditional orthodontic patients until very recently
. Finally, and most importantly, the retrospective nature of this limited pilot study did not allow for other demographic information about smoking habits, systemic health issues, or oral disease risk to be collected, which may provide more information and additional insights in future studies of this population.
These results have implications for clinical practice, specifically about how it may relate to the treatment and care of minorities. The results of this study are consistent with the most recent study of oral health literacy among minority populations, which found that although 82% of minority patients knew how to brush, thereby reducing SM populations and overall caries lesions, only 15% of patients knew how to floss, and flossed regularly
. The fact that nearly all of the patients testing positive for PG in this study were minority may point to a larger issue affecting populations that have lower health literacy, in general, and more specifically, much lower oral health literacy. The lack of statistically significant differences between males and females in this study further suggests that these phenomena are not specific to gender, but may be more pervasive among minority populations in this area who might benefit from additional oral health information, training, and targeted education initiatives from clinical dentistry. Although periodontitis in US minorities, most notably African Americans, have been well documented, fewer studies have focused on Hispanics
. The results of this study are particularly important to consider in Nevada, where recent estimates suggest that more than one-third of all state residents are minority and the vast majority of those (~80%) are Hispanic