Prevalence of target anaerobes associated with chronic periodontitis.

INTRODUCTION: Periodontal diseases are a group of chronic infections that destroy tissues surrounding and supporting the teeth. Data on the anaerobes associated with periodontal infections in Kuwait is lacking. AIM: To investigate the target anaerobes associated with chronic periodontitis (CP) in patients admitted to Dental Clinics in Kuwait University Health Sciences Center, Kuwait. METHODOLOGY: Patients with CP (severe and moderate) were recruited into this study during a period of 15 months. Samples were collected directly from inside the gingival pockets and subjected to semi-quantitative PCR assays. RESULTS: A total of 30 patients, stratified into moderate and severe CP and 31 healthy individuals, used as controls, were studied. Nine (30 %) of the 30 patients were in the 50-59-year age group. The detection rate of Aggregatibacter actinomycetemcomitans between the patients (9 : 30 %) versus the controls (5 : 16.1 %) was non-significant (P >0.05). Fusobacterium spp., were detected in all patients versus 29 (93.1 %) controls, (P >0.05). However, four target anaerobes were significantly associated with CP patients; Porphyromonas gingivalis was detected in ten (33.3 %) patients versus two (6.4 %) controls (P <0.0001); Tannerella forsythia 25 (83.3 %) versus 16 (51.6 %) controls (P <0.0001); Parvimonas micra 27 (90 %) versus 16 (51.6 %) controls (P <0.0001) and Treponema denticola, 18 (60 %) versus nine (29 %) controls (P <0.0001), respectively. Prevotella spp. were detected in 27 (90 %) patients and 30 (96.7 %) controls (P>0.5). There was no significant difference in the burden of Prevotella spp. between patients and controls determined by semi-quantitative PCR assays. CONCLUSION: Some (4/7) of the target anaerobes were significantly associated with CP in our study. P. gingivalis was the most strongly associated anaerobe with CP, although not the keystone bacteria, while Prevotella spp. was similar to the healthy controls.

Frictional coefficient during flossing of teeth.

OBJECTIVE: This in-vitro study aimed to develop a technique to measure the frictional forces and determine the frictional coefficient (µ) associated with the rubbing of dental floss against teeth. Incorrect flossing technique and the etiology of grooves at the cementoenamel junction (CEJ) of proximal area of teeth has long been a controversial topic. We hypothesized that the µ between teeth surfaces and dental floss is affected by contact angulation. MATERIALS AND METHODS: Tests were conducted using two different types of dental floss (waxed and unwaxed nylon) on different surfaces (enamel, dentine, smooth and rough glass rods) under different moisture conditions (dry and wet). The µ generated by performing C-shape flossing was measured, using the Capstan equation, at constant load (100g) over different flossing contact sliding angulations. In addition, the surface characteristics of intact and used nylon flosses were compared using a scanning electron microscope (SEM). RESULTS: The mean µ was highest with a smooth glass rod (0.42±0.11), followed by rough glass rods (0.30±0.07), dry enamel (0.27±0.08), wet enamel (0.23±0.06), then dentine (0.18±0.04). Moreover, higher µ was associated with waxed floss when used against dry enamel, smooth and rough glass rods (P<0.001). At different moisture conditions, waxed floss demonstrated greater µ with dry surfaces (P<0.03). No association was found between µ and dental floss contact angulation. Both floss types showed deterioration after usage; although waxed type exhibited markedly greater deterioration when used on dry surfaces. In conclusion, the magnitude of the µ was found to be influenced by surface roughness, moisture condition, and independent of the contact angulation area during sliding of dental floss. SIGNIFICANCE: It is important to consider the potential side effects of frictional forces on both tooth surface and dental floss during clinical application.

Denitrification potential of the Northern Arabian Gulf--an experimental study.

The study aims to establish denitrification potential of the Northern Arabian Gulf (NAG), as nitrogen critically affects the ocean productivity, obliterates acidity, oxidative capacity and radiative transfer capability of atmosphere. The experimental study was conducted by taking cores from intertidal zones from two different sites in North and South, referred as sites N and S; representing two distinct environmental milieu. The experiment was conducted in controlled laboratory conditions simulating the tidal cycles. Multiple cores were taken and loaded with seawater with different N concentrations, the redox potential was established for each condition. Redox potential was significantly lower at 10 cm depth compared to the surface in all cores (P < 0.001). The redox potential at surface and at 10 cm depth was significantly lower at site S compared to site N (P < 0.001; F = 714.2), suggesting anaerobic sediments at site S. Effects of nitrate spiked seawater on denitrification under nonflooded and flooded conditions at the two sites were also studied. Three-way ANOVA analysis indicated that site, nitrate concentration, and flooding had significant main and interactive effects on the rate of denitrification. The results suggest that under ambient nitrate concentrations (0.03 mg NO(3)-N l(-1)), 6.3 ± 2.1 g NO(3)-N ha day can be denitrified by inter-tidal zone sediments. At a nitrate concentration of 1 mg NO(3)-N l(-1), 92 ± 16 g NO(3)-N ha day may be denitrified whilst at a very high nitrate load of 10 mg NO(3)-N l(-1), the sediments may attain a rate of denitrification close to 404 ± 78 g NO(3)-N ha day.