Response to alkaline stress by root canal bacteria in biofilms

AIM: To determine whether bacteria isolated from infected root canals survive alkaline shifts better in biofilms than in planktonic cultures. METHODOLOGY: Clinical isolates of Enterococcus faecalis, Lactobacillus paracasei, Olsenella uli, Streptococcus anginosus, S. gordonii, S. oralis and Fusobacterium nucleatum in biofilm and planktonic cultures were stressed at pH 10.5 for 4 h, and cell viability determined using the fluorescent staining LIVE/DEAD BacLight bacterial viability kit. In addition, proteins released into extracellular culture fluids were identified by Western blotting. RESULTS: Enterococcus faecalis, L. paracasei, O. uli and S. gordonii survived in high numbers in both planktonic cultures and in biofilms after alkaline challenge. S. anginosus, S. oralis and F. nucleatum showed increased viability in biofilms compared with planktonic cultures. Alkaline exposure caused all planktonic cultures to aggregate into clusters and resulted in a greater extrusion of cellular proteins compared with cells in biofilms. Increased levels of DnaK, HPr and fructose-1,6-bisphosphate aldolase were observed in culture fluids, especially amongst streptococci. CONCLUSIONS: In general, bacteria isolated from infected roots canals resisted alkaline stress better in biofilms than in planktonic cultures, however, planktonic cells appeared to use aggregation and the extracellular transport of specific proteins as survival mechanisms.     

VCAM-1 and ICAM-1 are expressed by Langerhans cells, macrophages and endothelial cells in oral lichen planus

Expression of intercellular adhesion molecule-1 (ICAAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-l, CD106) was examined in oral lichen planus (OLP) and normal oral mucosa (NOM). Immunoperoxidase staining showed ICAM-1 expression by vascular endothelium in all biopsies of OLP and NOM whereas endothelial VCAM-l staining was found in 2/7 NOM and 8/9 OLP. In the lamina propria of NOM occasional cells were ICAM-1 or VCAM-l positive, and virtually no staining of intraepilhelial dendritic cells was seen for either marker. Intraepithelial dendritic cells stained for ICAM-1 in 7/9 and VCAM-1 in 4/9 OLP biopsies. Double immunofluorescence showed dual labelling of Langerhans cells (LC) with CD1a and VCAM-l in a further 5/12 cases of OLP, but there was no such staining in four NOM. This is the first report of LC staining with VCAAM-l. Induction of ICAM-1 and VCAM-l on LC and macrophages in OLP suggests these cells are activated and may contribute to the pathogenesis of OLP by presenting antigen to infiltrating lymphocytes.     

Clinical significance of holes in gloves for dental use: a spectrophotometric analysis.

The aim of this study on latex dental gloves was to establish whether there is any relationship between faults that are detected by filling with water and the entry of liquid into the gloves during use. Twenty-four gloves of different sizes were examined. Large and small holes randomly distributed on the index, middle, and ring fingers, were made in the gloves. The gloves were filled with water and squeezed to detect the amount of water escaping. A mass spectrophotometer was used with the same gloves to quantify the entry of an aqueous solution of potassium bichromate during work. The filling method was effective for revealing all faults in gloves, but it was not able to determine whether there would be fluid entry through the holes during work. While the size of the holes was not predictive for the amount of liquid entering the glove, adherence of the glove to the hand was. Holes of the same size allowed a greater entry of contaminated liquid in adherent gloves than in looser ones.     

HIV parotid gland lymphoepithelial cysts. Review and case reports.

Lymphoepithelial cysts of the parotid gland are frequently associated with cervical lymphadenopathy. These unique cysts have recently been recognized as another manifestation of HIV disease. Proliferation of lymphocytes and salivary gland tissue contained within intra-parotid lymph nodes is observed. The lymphoepithelial cyst is the end product. Ultrasound imaging serves as an excellent technique to demonstrate the existence of these cysts.     

A study of bond strength between light- and self-cured orthodontic resin.

Light-cured orthodontic composite resin has been widely advertised recently for use in bonding. However, the curability of light-cured resin when light waves are diffused through metal, ceramic, or resin brackets is doubtful and questionable. This study evaluated the effectiveness of a visible light source in curing the resin under a solid metal bracket, compared the tensile bond strength at different exposures, and analyzed the broken interface distribution between light-cured resin with various light exposure times and self-cured resin. The bond strength results revealed that the difference between light-cured resin (Transbond) with 60, 40, and 20 seconds of light exposure, respectively, and self-cured resin (Concise) was 1.05, 0.92, 0.61, and 0.71 kg/mm2, respectively. The bond strength of Transbond with 60 and 40 seconds of light exposure was greater than both the bond strength of Transbond with 20 seconds of light exposure and the strength of the self-cured resin of Concise, with statistical significance (p less than 0.01). There were also no statistical differences between Transbond with 60 and 40 seconds of light exposure or Transbond with 20 seconds of light exposure and Concise. The bond failure interfaces were located between the bracket and the resin, within the resin itself, or between the resin and the enamel. Tooth fragmentation was rarely found. There were no statistical differences (p greater than 0.05) among broken interfaces. This indicates that visible light is powerful in curing the visible light-activated composite resin under solid metal brackets.(ABSTRACT TRUNCATED AT 250 WORDS)     

A 5- and 8-year clinical evaluation of a posterior composite resin

Class I and II posterior composite resin (Ful-Fil) restorations were placed and were clinically evaluated, according to the US Public Health Service criteria, at baseline, 6 months, 5 years, and 8 years. At 5 years/8 years, alpha scores were assigned to the following percentages of restorations: 16%/31% for color match; 65%/62% for marginal discoloration; 74%/54% for cavosurface marginal discoloration; 100%/100% for axial contour; and 81%/65% for anatomic form. At 5 years/8 years, 56%/33% of Class II restorations had tight proximal contacts; 45%/44% had light contacts; and 0%/22% had no contacts. Transient postoperative sensitivity was reported in 6% of the restorations. Indirect evaluation indicated that there was an average of 64 +/- 35 microns of wear at baseline (because of overfinishing), 105 +/- 67 microns at 6 months, 217 +/- 76 microns at 5 years, and 253 +/- 82 microns at 8 years. At 5 years, three of the restorations, and at 8 years, four additional restorations, were clinically unacceptable because of recurrent caries and/or excessive wear. Final success rates of 90% and 77% at 5 and 8 years, respectively, were calculated.     

Effect on the incidence of oral submucous fibrosis of intervention in the areca nut chewing habit

Incidence of oral submucous fibrosis was calculated from a 10-yr prospective intervention study of 12,212 individuals with a strong component of health education on tobacco and area nut chewing. Based on 11 new cases among 6341 chewers, the annual incidence was 8.0 per 100,000 among men and 29.0 for women. An earlier 10-yr follow-up study, with no intervention component, served as control. Based on 11 new cases among 3,809 chewers, the annual incidence was 21.3 per 100,000 for men and 45.7 for women controls. Although the decrease in the incidence in the intervention cohort was not statistically significant due to small number of cases, the results underscored the causal role of areca nut chewing and indicated the potential for primary prevention of oral submucous fibrosis.