Preclinical teaching of periodontal surgical concepts using common instructional models: A comparative assessment.

OBJECTIVES: Some commonly used models utilized for teaching periodontal surgical techniques to dental students include pig mandible and periodontal typodonts. Currently, no study compares the learning and teaching outcomes following the use of one model to the other. This study is aimed at evaluating the effectiveness of the preclinical laboratory component on student understanding of concepts taught in the periodontal surgical course and assessing students' and faculty members' satisfaction with the instructional models. METHODS: As part of the surgical periodontics course, 98 students took the final exam, with eighty students participating in only the pig mandible session and twenty-three students participating in both the pig jaw mandible and an additional session utilizing periodontal typodonts under the supervision of ten periodontal faculty members. Examination scores of students attending or not attending the laboratory session were analyzed by a two-sample t-test. A questionnaire evaluating the effectiveness of both models was given to faculty members and students who participated in both laboratory sessions. These results were analyzed by paired t-test. RESULTS: Participation in the laboratory sessions did not significantly impact the final exam scores (p = 0.722). Students who had better didactic performance in the course performed better in the final exam, irrespective of laboratory participation. Both students and faculty members preferred typodont to the pig mandibles in learning or teaching periodontal surgical concepts, but both felt gaining flap management and flap refection experience to be better with the pig mandible model without statistical significance (p = 0.119 and p = 0.070, respectively). CONCLUSION: Within the limitations of this study, we can conclude that laboratory sessions did not significantly improve student performance on the exam. Students and faculty members generally gave positive feedback on both instructional models. Periodontal typodont could be an alternative model for teaching dental students, periodontal surgical concepts.

Cone-Beam Computed Tomography Analysis of the Prevalence, Length, and Passage of the Anterior Loop of the Mandibular Canal.

When placing implants in the anterior mandible, it is important to avoid damaging the mandibular nerve and its terminal extensions. The objective of this study was to determine the prevalence, length, and passage of the anterior loop of the mandibular canal, as well as the quantity of alveolar bone that is coronal to the canal, to help with implant placement in the anterior mandible. Cone-beam computerized tomography (CBCT) scans of 124 patients with 248 hemi-sections were evaluated. Anterior loop prevalence was determined using reconstructed panoramic and cross-sectional views; length was measured as the distance between the most mesial aspect of the mental foramen to the most mesial aspect of the anterior loop on cross-sectional views. The bucco-lingual position of the anterior loop inside the mandible and the apico-coronal dimensions of the alveolar bone above it were measured on cross-sectional views to determine the passage of the anterior loop and the bone available coronally, respectively. The effects of sex, age, side, and dentate status on the prevalence and length of the anterior loop were analyzed statistically. Prevalence of the anterior loop at the patient and hemi-section levels was 25% and 24%, respectively, and its median length was 1.63 mm (range, 0.52-3.92 mm). The anterior loop was apical to the mental foramen and mostly located within the buccal or middle one-third of the alveolar ridge, with an average height of coronal alveolar bone of 17.12 mm. Sex, age, side, and dentate status did not affect anterior loop prevalence and length. In conclusion, because of great variation, a case-by-case CBCT evaluation of the anterior loop is necessary before placing implants in the anterior mandible.

Frequency of Tongue Cleaning Impacts the Human Tongue Microbiome Composition and Enterosalivary Circulation of Nitrate.

The oral microbiome has the potential to provide an important symbiotic function in human blood pressure physiology by contributing to the generation of nitric oxide (NO), an essential cardiovascular signaling molecule. NO is produced by the human body via conversion of arginine to NO by endogenous nitric oxide synthase (eNOS) but eNOS activity varies by subject. Oral microbial communities are proposed to supplement host NO production by reducing dietary nitrate to nitrite via bacterial nitrate reductases. Unreduced dietary nitrate is delivered to the oral cavity in saliva, a physiological process termed the enterosalivary circulation of nitrate. Previous studies demonstrated that disruption of enterosalivary circulation via use of oral antiseptics resulted in increases in systolic blood pressure. These previous studies did not include detailed information on the oral health of enrolled subjects. Using 16S rRNA gene sequencing and analysis, we determined whether introduction of chlorhexidine antiseptic mouthwash for 1 week was associated with changes in tongue bacterial communities and resting systolic blood pressure in healthy normotensive individuals with documented oral hygiene behaviors and free of oral disease. Tongue cleaning frequency was a predictor of chlorhexidine-induced changes in systolic blood pressure and tongue microbiome composition. Twice-daily chlorhexidine usage was associated with a significant increase in systolic blood pressure after 1 week of use and recovery from use resulted in an enrichment in nitrate-reducing bacteria on the tongue. Individuals with relatively high levels of bacterial nitrite reductases had lower resting systolic blood pressure. These results further support the concept of a symbiotic oral microbiome contributing to human health via the enterosalivary nitrate-nitrite-NO pathway. These data suggest that management of the tongue microbiome by regular cleaning together with adequate dietary intake of nitrate provide an opportunity for the improvement of resting systolic blood pressure.

Poor Oral Health Linked with Increased Risk of Infectious Complications in Adults with Leukemia.

OBJECTIVE: The objective of this study is to examine the impact of the presence of gingivitis/periodontitis on the occurrence of infectious complications (including septicemia, bacterial infections, and mycoses) in hospitalized leukemic adults in the United States. METHODS: A retrospective analysis of the Nationwide Inpatient Sample (NIS) for the years 2004-2010 was performed. All hospitalized leukemic patients aged 18 to 65 years were selected. The association between occurrence of gingivitis/periodontitis and infectious complications was examined by multivariable logistic regression models. A total of 135,692 hospitalizations were due to leukemias during the study period. Among these, gingivitis/periodontitis was present in 0.6%. Septicemia occurred in 27.8% of those who had gingivitis/periodontitis (compared to 19.6% in those without gingivitis/periodontitis), bacterial infections occurred in 19.5% of those who had gingivitis/periodontitis (compared to 10.1% in those without gingivitis/periodontitis), and mycoses occurred in 20.7% of those who had gingivitis/periodontitis (compared to 10.7% in those without gingivitis/periodontitis). Patients who had gingivitis/periodontitis were associated with significantly higher odds for septicemia (OR = 1.58, 95% CI = 1.14-2.19, p = 0.01), bacterial infections (OR = 2.15, 95% CI = 1.51-3.07, p<0.01), mycoses (OR = 2.16, 95% CI = 1.43-3.28, p<0.01), or any infectious complication (OR = 2.15, 95% CI = 1.63-2.84, p<0.01) when compared to their counterparts following adjustment for multiple patient and hospital-level confounding factors. CONCLUSIONS: Poor oral health (as defined by the presence of gingivitis/periodontitis) is an independent predictor of increased risk of infectious complications in hospitalized leukemic adults in the United States.

Hospital-based emergency department visits with herpetic gingivostomatitis in the United States.

OBJECTIVES: The objectives of this study were to determine the number of hospital emergency department (ED) visits with a diagnosis of herpetic gingivostomatitis (HGS) for 2007 in the United States and to identify the possible comorbid conditions associated with HGS. STUDY DESIGN: The Nationwide Emergency Department Sample for 2007 was used in this study. Patients who visited the ED with a diagnosis of HGS were selected. Estimates were projected to the national levels using the discharge weights. Presence of comorbid conditions in these patients was also analyzed. RESULTS: A total of 23,124 patients had ED visits and received the diagnosis of HGS. Most of the patients were young females and those belonging to the lower socioeconomic strata. All patients with HGS also presented with comorbid conditions. CONCLUSIONS: Physicians should be trained to diagnose, manage, and refer common dental emergencies. In the long term, improving access to dental care for these patients is crucial to managing this problem.

MMP-9/TIMP-1 imbalance induced in human dendritic cells by Porphyromonas gingivalis.

Matrix metalloproteinase-9 (MMP-9) cleaves collagen, allowing leukocytes to traffic toward the vasculature and the lymphatics. When MMP-9 is unregulated by tissue inhibitor of metalloproteinase-1 (TIMP-1), this can lead to tissue destruction. Dendritic cells (DCs) infiltrate the oral mucosa increasingly in chronic periodontitis, characterized by infection with several pathogens including Porphyromonas gingivalis. In this study, human monocyte-derived DCs were pulsed with different doses of lipopolysaccharide of P. gingivalis 381 and of Escherichia coli type strain 25922, as well as whole live isogenic fimbriae-deficient mutant strains of P. gingivalis 381. Levels of induction of MMP-9 and TIMP-1, as well as interleukin-10 (IL-10), which reportedly inhibits MMP-9 induction, were measured by several approaches. Our results reveal that lipopolysaccharide of P. gingivalis, compared with lipopolysaccharide from E. coli type strain 25922, is a relatively potent inducer of MMP-9, but a weak inducer of TIMP-1, contributing to a high MMP-9/TIMP-1 ratio.Whole live P. gingivalis strain 381, major fimbriae mutant DPG-3 and double mutant MFB were potent inducers of MMP-9, but minor fimbriae mutant MFI was not. MMP-9 induction was inversely proportional to IL-10 induction. These results suggest that lipopolysaccharide and the minor and the major fimbriae of P. gingivalis may play distinct roles in induction by DCs of MMP-9, a potent mediator of local tissue destruction and leukocyte trafficking.