Evaluation of Streptococcus mutans adhesion to fluoride varnishes and subsequent change in biofilm accumulation and acidogenicity

Objectives

The aim of this study was to evaluate Streptococcus mutans adhesion to fluoride varnishes and subsequent change in biofilm accumulation and acidogenicity.

Methods

After producing fluoride varnish-coated hydroxyapatite discs using Fluor Protector (FP), Bifluorid 12 (BIF), Cavity Shield (CASH), or Flor-Opal Varnish White (FO), S. mutans biofilms were formed on the discs. To assess S. mutans adhesion to the discs, 4-h-old biofilms were analysed. To investigate the change in biofilm accumulation during subsequent biofilm formation, the biomass, colony forming units (CFU), and water-insoluble extracellular polysaccharides (EP) of 46-, 70-, and 94-h-old biofilms were analysed. To investigate the change in acidogenicity, pH values of the culture medium were determined during the experimental period. The amount of fluoride in the culture medium was also determined during the experimental period.

Results

BIF, CASH, and FO affected S. mutans adhesion (67–98% reduction) and subsequent biofilm accumulation in 46-, 70-, and 94-h-old biofilms. However, the reducing effect of the fluoride varnishes on the biomass, CFU count, water-insoluble EP amount, and acid production rate of the biofilms decreased as the biofilm age increased. These results may be related to the fluoride-release pattern of the fluoride varnishes. Of the fluoride varnishes tested, FO showed the highest reducing effect against the bacterial adhesion and subsequent biofilm accumulation.

Conclusions

Our findings suggest that if the results of these experiments are extrapolable to the in vivo situation, then reduced clinical benefit of using fluoride varnishes may occur with time.

Clinical significance

Fluoride varnish application can affect cariogenic biofilm formation but the anti-biofilm activity may be reduced with time.     

Radiographic assessment of clinical root-crown ratios of permanent teeth in a healthy Korean population

PURPOSE

The aim of this study was to determine the absolute value of the root/crown ratio (R/C ratio) using panoramic radiographs (PRGs) in a healthy Korean population.

MATERIALS AND METHODS

In total, 99 patient radiographs (of 50 males and 49 females subjects; aged 16 to 24 years old) were examined, and 2,770 teeth were analyzed. Crown lengths and root lengths were measured with modified Lind''s measurements using PACS tools by two examiners in two separate sessions two months apart. All data were analyzed using SPSS. The independent t-test was used to assess for gender differences, and the paired t-test was used to compare both arches with a significance level of P<.05.

RESULTS

The mean R/C ratios varied from 1.29 to 1.89 (male: 1.28-1.84; females: 1.31-1.94). The highest R/C ratios were recorded for the mandibular canines (1.89), followed by the maxillary canines (1.79). The lowest R/C ratios were recorded for the maxillary second molars (1.31). In comparison with the maxillary teeth (1.29-1.78), the mandibular teeth yielded the higher R/C ratio (1.47-1.89), and this difference was significant in the females (P<.05). The difference between the genders was not statistically significant, except for the maxillary central incisors, mandibular canines and mandibular first premolars.

CONCLUSION

These data may enhance the understanding of the clinical R/C ratio as a useful guideline for determining the status of teeth and the ethnic difference.     

Noninvasive quantitation of blood flow turbulence in patients with aortic valve disease using online digital computer analysis of Doppler velocity data.

Previous experimental studies have demonstrated that aortic valve disease is associated with significant downstream turbulence (T). In this study, we developed a noninvasive method on the basis of Doppler velocity recording for quantitating aortic blood flow T in patients with aortic valve disease. The instantaneous blood velocity at a point in the aorta is equal to the sum of a mean periodic velocity component with a random or turbulent velocity component. According to the ensemble average method, time mean absolute T intensity is the root-mean-square value of turbulent velocity averaged over time and T is better quantitated by the relative T intensity (TIr), which is the ratio of absolute T intensity to the ensemble average velocity averaged over time. We computed TIr in 18 patients with mild to severe aortic stenosis and in 13 healthy volunteers from instantaneous modal velocities of 70 cycle length-matched heart beats recorded in the proximal part of the descending aorta by pulsed Doppler using an ultrasound system with an output port for online digital data transfer into a microcomputer. TIr was greater in patients with aortic valve disease (18.4 +/- 5.1%, range 11.2%-28.9%) than in control patients (7.9 +/- 1.9%, range 4.8%-9.8%; P =.0001). In patients with aortic valve disease, TIr was better linearly related to the ratio of postvalvular aorta to valvular orifice cross-sectional areas (r = 0.89, P =.0001) than to other parameters of valve restriction: transvalvular pressure gradient (r = 0.78, P =.0001); valve area (r = -0.56, P =.01); and valve resistance (r = 0.72, P =.0002). Thus, T that can be computed noninvasively from direct digital transfer of Doppler velocity data appears to be linearly related to indices of aortic valve restriction. Our data support the concept of the postvalvular aorta to valvular orifice cross-sectional areas ratio as a new important hemodynamic parameter in patients with aortic valve disease.     

Cross‐reactivity between decellularized porcine corneal lamellae for corneal xenobridging and subsequent corneal allotransplants

The purpose of this study is to investigate cross‐reactivity between hypertonic saline‐treated decellularized porcine corneal lamellae for corneal xenobridging and subsequent corneal allotransplants. Five Chinese rhesus macaques, which had undergone anterior partial thickness corneal transplantation using hypertonic saline‐treated decellularized porcine corneal lamellae in preceding experiments, were used as recipients for subsequent full‐thickness corneal allografts. To determine whether sensitization of recipients to xenoantigens leads to cross‐reactivity against alloantigens, we compared; (i) allogeneic one‐way mixed lymphocyte reaction (MLR) of peripheral blood mononuclear cells (PBMCs) from xeno‐sensitized recipients with that of PBMCs from naïve rhesus macaques, and (ii) amounts of IgG antibodies that bound to the PBMCs of a rhesus panel (five monkeys) before and after xeno‐sensitization. Graft survival and immunologic profiles including memory T‐cell subsets and donor rhesus‐specific antibodies were also evaluated. No hyperacute or acute rejection was observed within a month of subsequent allotransplantation in any recipient. Alloreactivity by MLR was not different between xeno‐sensitized rhesus recipients and naïve rhesus monkeys. Panel‐reactive IgG antibodies were unchanged after xeno‐sensitization, and no change in donor rhesus‐specific antibodies was observed in any recipient. No significant changes in memory T‐cell subsets were observed during the early post‐operative period in any recipient. Decellularized porcine corneal lamellae may not increase cross‐reactivity to alloantigens, and thus, porcine corneal lamellae may be used as a bridge to subsequent corneal allografting.