Tetracycline, an Appropriate Reagent for Measuring Bone-Formation Activity in the Murine Model of the Streptococcus mutans-Induced Bone Loss

Tetracycline is used as a fluorescent reagent to measure bone formation activity in bone histomorphometric analyses. However, there is a possibility to lead a different conclusion when it is used in a bacteria-infected murine model since the tetracycline is considered to work as an antibiotic reagent. There are non-antibiotic fluorescent reagents such as alizarin and calcein for measuring bone formation activity. The purpose of this study was to clarify whether tetracycline could be an appropriate reagent to measure bone formation activity in a murine bacterial model in the same way as a non-antibiotic fluorescent reagent. We used Streptococcus mutans (S. mutans), a normal inhabitant in the oral cavity and tetracycline-sensitive bacteria, for inducing the bacterial model. The murine bacterial model was generated by intravenously inoculating S. mutans to the tail vein, followed immediately by the injection of the first fluorescent reagent, and the second one was injected 2 days prior to euthanization. After one day of inoculation with S. mutans, the subcutaneously injected alizarin had a similar colony count derived from the liver and the bone marrow tissue compared to the phosphate buffered saline (PBS)-injected control group. On the other hand, subcutaneous injection of tetracycline led to a significantly lower colony count from the liver compared to alizarin- or calcein-injected group. However, on day seven, after S. mutans intravenous injections, bone mineral density of distal femurs was significantly reduced by the bacteria inoculation regardless of which fluorescent reagents were injected subcutaneously. Finally, S. mutans inoculation reduced bone-formation-activity indices in both the tetracycline-alizarin double-injected mice and the calcein-alizarin double-injected mice. These results suggested that a one-time injection of tetracycline did not affect bone formation indices in the S. mutans-induced bone loss model. Tetracycline could be used for measuring bone formation activity in the same way as non-antibiotic fluorescent reagent such as calcein and alizarin, even in a tetracycline-sensitive bacterium-infected model.

Anti-Demineralization Effects of Dental Adhesive-Composites on Enamel-Root Dentin Junction

Oral biofilm reactor (OBR) and pH cycling (pHC) artificial caries model were employed to evaluate the anti-demineralization effects of four composite filling systems on enamel-root dentin junction. Sixty-four enamel-root dentin blocks (6 mm × 6 mm × 2 mm) each with a cylindrical cavity were randomly assigned to the pHC and OBR group, then four subgroups (n = 8) and filled with either the Beautifil II (BEF, SPRG-filler-containing) or Estelite (EST) composite after the adhesive (either Single Bond Universal (SBU) or FL Bond II (FL, SPRG-filler-containing)). The demineralization lesions of filling interface were examined by micro-computerized tomography (μCT) and swept-source-optical coherence tomography (SS-OCT). According to the degree of interface damage, the caries lesions were sorted into four types: Type A and B (no attachment loss); Type C and D (attachment loss). EST/SBU showed the worst demineralization lesion and attachment loss (100% Type D), while BEF/FL exhibited the shallowest lesion depth (p < 0.05, 145 ± 45 μm on enamel, 275 ± 35 μm on root dentin) and no attachment loss (75% Type A and 25% Type B). Using FL adhesive alone does not effectively reduce enamel demineralization. BEF plays a leading role in acid resistance. The combination of BEF and FL showed a cumulative synergistic effect on anti-demineralization.

Effect of advanced periodontal self-care in patients with early-stage periodontal diseases on endothelial function: An open-label, randomized controlled trial

Although a significant association between periodontal disease and atherosclerotic cardiovascular disease has been reported, their cause-to-effect relationship remains controversial. This randomized controlled clinical trial aimed to investigate the effect of advanced self-care on atherosclerotic cardiovascular disease-related vascular function markers flow-mediated brachial artery dilatation (FMD) and serum asymmetric dimethylarginine (ADMA) level in patients with early-stage periodontal disease. The study was designed as a parallel group, 3-month follow-up, open-label, randomized controlled trial. The control group received standard care for periodontal diseases, whereas the test group additionally applied disinfectant using a custom-fabricated prescription tray for advanced self-care twice a day. Overall, 110 patients provided data for FMD and serum ADMA level. No significant improvements in FMD were observed in the control (mean increase, −0.1%; 95% confidence interval [CI], −1.0–0.8; P = 0.805) or test (mean increase, −0.3%; 95% CI, −1.1–0.4; P = 0.398) group. No significant changes in serum ADMA levels were observed (mean reduction, 0.01 μmol/L; 95% CI, −0.00–0.02; P = 0.366 and mean reduction, 0.00 μmol/L; 95% CI, −0.01–0.01; P = 0.349, respectively). No significant between-group differences were found in FMD (mean difference, −0.2%; 95% CI, −1.4–0.9; p = 0.708) or serum ADMA levels (mean difference, 0.01 nmol/L; 95% CI, −0.00–0.03; p = 0.122). Significant improvements in the average probing pocket depth were observed in the control and test groups. The bleeding on probing score in the test group was significantly reduced, while that in the control group was reduced, although not significantly. Periodontal care for a 3-month duration did not provide better endothelial function although improvements of periodontal status in patients with early-stage periodontal diseases. This trial is registered in UMIN Clinical Trials Registry (www.umin.ac.jp/ctr/; ID: UMIN000023395).

Characteristics of biofilm-induced degradation at resin-dentin interfaces using multiple combinations of adhesives and resins

OBJECTIVE

We aimed to evaluate morphological, mechanical and chemical characteristics at resin-dentin interfaces using multiple combinations of adhesives and resins after a short-term biofilm-induced degradation.

METHODS

Cervical cavities were prepared in bovine incisors, treated by Clearfil SE Bond 2 (SE) or FL-Bond II (FL), restored by Clearfil Majesty ES Flow (ES) or Beautifil Flow Plus (BFP) and grouped into SE-ES, SE-BFP, FL-ES and FL-BFP. After biofilm challenge, interfacial gaps and dentin wall lesions were examined by optical coherence tomography (OCT). Gap depth (GD), gap pattern scale (GPS) and dentin wall lesion depth (WLD) were evaluated from confocal laser scanning microscope. Microhardness of dentin lesions was measured with a Vickers microhardness tester. Chemical elements in resins and dentin wall lesions were analyzed by scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS). Morphological structures of interfacial gaps were observed by SEM.

RESULTS

OCT could detect adhesive-dentin-bonded and adhesive-dentin-debonded gaps. SE-containing groups showed significantly lower GPS than FL-containing groups. FL-BFP showed significantly lower WLD than FL-ES. Microhardness of dentin wall lesions was higher than that of outer lesions and they showed significant differences in FL-BFP. SE-BFP showed a lower GPS curve and higher intensities of Ca and P in the upper half of dentin wall lesions than other groups. From SEM, microgaps between filler and matrix, break and loss of matrix, separation of adhesive matrix with hybrid layer occurred at interfacial gaps.

SIGNIFICANCE

The morphological, mechanical and chemical characteristics of resin-dentin interfacial degradation depend on the component and chemistry of restorative materials.

Effects of silver diamine fluoride preparations on biofilm formation of Streptococcus mutans

Effects of silver diamine fluoride preparations (SDFs) on cariogenic biofilm formation on root dentin (RD) were investigated. Streptococcus mutans (S. mutans) biofilms were formed on bovine RD blocks coated with one of three the SDFs (38%-SDF, 3.8%-SDF and 35%-SDF+potassium-iodide; SDF+KI) and a non-coated Control which were quantified (spectrometric-measurement) and thickness measured (optical coherence tomography) after 20 h. Bacterial viability test (BacLight) and biofilm-morphometry (SEM) of 2 h biofilms were also performed. The amounts of biofilms (bacteria and water insoluble glucan) and the thickness of biofilm were minimum on 38%-SDF specimen; 3.8%-SDF and SDF+KI had significantly more than that, but had significantly less than Control (p<0.05). Most S. mutans cells found dead and morphology damaged by 38%-SDF. Some dead bacteria and remarkably damaged biofilms were observed in case of 3.8%-SDF and SDF+KI. Inhibition potential of 3.8%-SDF and SDF+KI on S. mutans biofilm formation is almost similar, although not equivalent to 38%-SDF.

Detection and analysis of early degradation at resin-dentin interface by optical coherence tomography (OCT) and confocal laser scanning microscope (CLSM)

OBJECTIVE

To evaluate early degradation at resin-dentin interface using non-invasive swept-source optical coherence tomography (SS-OCT) and confocal laser scanning microscope (CLSM).

METHODS

Self-etch adhesives and resin-composites containing bisphenol-glycidyl-dimethacrylate (Bis-GMA), which is one of the most widely used monomers in restorative materials, were investigated in this study. Forty cervical cavities were prepared in bovine incisors and applied by the adhesive with/without Bis-GMA (AdhesiveBG/Adhesive), filled by the resin with/without Bis-GMA (ResinBG/Resin) and then challenged by cariogenic biofilm (37 °C, 24 h). Gap Formation and dentin demineralization around resin-composites were observed by SS-OCT and CLSM.

RESULTS

Three types of resin-dentin interfacial degradation could be detected from SS-OCT. Type I-dentin demineralization around resin without gap, showing feather-shaped dark zones without bright scattered lines at resin-dentin interfaces. Type II-dentin demineralization around resin with adhesive-dentin bonded gaps, showing feather-shaped dark zones with bright scattered lines at resin-dentin interfaces. Type III-dentin demineralization around resin with adhesive-dentin debonded gaps, showing edge-shaped dark zones with bright scattered lines at resin-dentin interface. From CLSM, the groups were compared in gap scale (GS), gap depth (GD), gap width (GW) and dentin wall lesion depth (WLD). Bis-GMA-containing adhesive groups showed significantly lower GS than Bis-GMA-free adhesive groups. Bis-GMA-containing resin groups showed significantly lower WLD than Bis-GMA-free resin groups. However, they did not show significant differences in GD and GW.

CONCLUSION

Three types of early degradation at resin-dentin interface can be noninvasively detected by SS-OCT. Bis-GMA-containing and Bis-GMA-free restorative materials show differences in gap scale and dentin wall lesion depth.

CLINICAL SIGNIFICANCE

SS-OCT can nondestructively detect early resin-dentin interfacial degradation. Gap scale can be used as a parameter to evaluate the risk factor of gaps.

Effects of mechanical abrasion challenge on sound and demineralized dentin surfaces treated with SDF

This study evaluated the effect of mechanical abrasion on the surface integrity, color change (ΔE) and antibacterial properties of demineralized and sound dentin surfaces treated with silver-diammine-fluoride (SDF). The dentin specimens were divided into two groups: sound and demineralized dentin, then divided into three sub-groups, control (no-treatment), SDF, and SDF + potassium-iodide (KI). Each sub-group was further divided into two groups, one exposed to mechanical brushing and the other without brushing. Specimens were analyzed for the ΔE, surface roughness/surface loss and antibacterial properties (CFU, optical density and fluorescent microscope). Repeated Measures ANOVA was used for statistical analysis of color change while one-way ANOVA was used for CFU analysis. SDF and SDI + KI groups showed significant reduction in ΔE with brushing in the sound dentin group unlike the demineralized group. The surface roughness values were higher for both SDF and SDF + KI groups but roughness values significantly decreased after brushing. Both SDF and SDF + KI groups revealed significantly less surface loss than control. The SDF group showed high anti-bacterial effect after brushing, unlike SDF + KI group. So, we concluded that mechanical brushing improved the esthetic outcome. While, SDF and SDF + KI could protect the dentin surface integrity. SDF-treated dentin possesses an antibacterial property even after mechanical brushing.

Effects of a surface prereacted glass-ionomer filler coating material on biofilm formation and inhibition of dentin demineralization

OBJECTIVES

This study investigated the ability of a surface prereacted glass-ionomer (S-PRG) coating material to inhibit the biofilm formation and demineralization of dentin.

METHODS AND MATERIALS

Dentin specimens were randomly divided into three groups: (1) no coating (control), (2) S-PRG filler-containing coat, and (3) a nonS-PRG filler-containing coat. Streptococcus mutans biofilms were grown on the dentin surfaces in a microcosm for 20 h. Then, the quantity of bacteria and water-insoluble glucan in the retained biofilm on the dentin surface were measured. Regarding demineralization inhibition test, specimens were demineralized for 5 days then sectioned into halves and observed under confocal laser scanning microscope (CLSM). One-way ANOVA and Tukey's HSD were used for statistical analysis.

RESULTS

The estimated mean surface roughness for specimens in the S-PRG group was statistically significantly higher than the estimates for both the nonS-PRG and the control group specimens. The quantity of bacteria and water-insoluble glucan/mm² revealed that the S-PRG group prevented biofilm formation and bacterial adhesion to the dentin surface compared with the control and nonS-PRG groups. The S-PRG group recorded the highest acid-resistance ability with no surface loss.

CONCLUSION

Application of S-PRG barrier coat on dentin surfaces can inhibit biofilm formation as well as protecting the dentin surface against demineralization.

CLINICAL SIGNIFICANCE

Coating material containing S-PRG fillers might be used for caries prevention, through inhibiting biofilm formation, enhancing mineralization, and reducing acidic attack by cariogenic bacteria.

Inhibitory effect of zinc-containing desensitizer on bacterial biofilm formation and root dentin demineralization

This study compared the effect of a novel zinc containing, Caredyne Shield (CS), and a fluoroaluminocalciumsilicate-based, Nanoseal (NS) desensitizers on dentin tubule occlusion, inhibition of Streptococcus mutans (S. mutans) biofilm growth, and resistance to bacterial demineralization. Desensitizers were applied to simulated hypersensitive bovine dentin, with distilled water used as a control. S. mutans biofilms were grown on the surface of each specimen in an oral biofilm simulator. CS showed the least bacterial count and water insoluble glucan amount followed by NS. Transverse micro radiography revealed that both CS and NS showed significant reduction in mineral loss and lesion depth of the associated lesion. Scanning electron micrographs showed that the two desensitizers formed obvious depositions on the dentin surfaces, occlusion of tubules and mineral tag formation.

Assessment of root caries under wet and dry conditions using swept-source optical coherence tomography (SS-OCT)

The purpose of this study was to compare optical properties of root caries under two observing conditions using swept-source optical coherence tomography (SS-OCT). In vitro and natural root caries were observed by SS-OCT under wet and dry conditions, followed by confocal laser scanning microscope (CLSM) and transverse microradiography (TMR). Signal intensity (SI), distance between SI peaks (SI-distance) and optical lesion depth were obtained from OCT. Lesion depth was measured from CLSM; lesion depth (LD_TMR) and mineral loss (ML) were obtained from TMR. In vitro root caries under wet and dry conditions showed different OCT images and SI patterns. Lesion depth of OCT and that of CLSM, SI-distance and LD_TMR, LD_TMR and ML significantly correlated. Under dry conditions, half natural root caries showed similar OCT images and SI patterns as in vitro root caries. The base of demineralized dentin could be detected more clearly under dry conditions than under wet conditions.

Generation of a Gene-disrupted Streptococcus mutans Strain Without Gene Cloning

Typical methods for the elucidation of the function of a particular gene involve comparative phenotypic analyses of the wild-type strain and a strain in which the gene of interest has been disrupted. A gene-disruption DNA construct containing a suitable antibiotic resistance marker gene is useful for the generation of gene-disrupted strains in bacteria. However, conventional construction methods, which require gene cloning steps, involve complex and time-consuming protocols. Here, a relatively facile, rapid, and cost-effective method for targeted gene disruption in Streptococcus mutans is described. The method utilizes a 2-step fusion polymerase chain reaction (PCR) to generate the disruption construct and electroporation for genetic transformation. This method does not require an enzymatic reaction, other than PCR, and additionally offers greater flexibility in terms of the design of the disruption construct. Employment of electroporation facilitates the preparation of competent cells and improves the transformation efficiency. The present method may be adapted for the generation of gene-disrupted strains of various species.

Optical analysis of enamel and dentin caries in relation to mineral density using swept-source optical coherence tomography

The aim of this study was to evaluate the signal intensity and signal attenuation of swept source optical coherence tomography (SS-OCT) for dental caries in relation to the variation of mineral density. SS-OCT observation was performed on the enamel and dentin artificial demineralization and on natural caries. The artificial caries model on enamel and dentin surfaces was created using Streptococcus mutans biofilms incubated in an oral biofilm reactor. The lesions were centrally cross sectioned and SS-OCT scans were obtained in two directions to construct a three-dimensional data set, from the lesion surface (sagittal scan) and parallel to the lesion surface (horizontal scan). The integrated signal up to [Formula: see text] in depth (IS200) and the attenuation coefficient ([Formula: see text]) of the enamel and dentin lesions were calculated from the SS-OCT signal in horizontal scans at five locations of lesion depth. The values were compared with the mineral density obtained from transverse microradiography. Both enamel and dentin demineralization showed significantly higher IS200 and [Formula: see text] than the sound tooth substrate from the sagittal scan. Enamel demineralization showed significantly higher IS200 than sound enamel, even with low levels of demineralization. In demineralized dentin, the [Formula: see text] from the horizontal scan consistently trended downward compared to the sound dentin.

Assessment of bacterial demineralization around composite restorations using swept-source optical coherence tomography (SS-OCT)

OBJECTIVE

To observe the bacterial demineralization of the enamel and dentin around composite restorations bonded with one-step and two-step self-etch adhesive systems using swept-source optical coherence tomography (SS-OCT).

METHODS

Forty class V cavities (2.5-mm surface diameter, 2.0-mm maximum depth) were prepared on cervical areas of 20 human molars. The specimens were either treated with one-step adhesive (Clearfil Tri-S Bond ND Quick; TS) or two-step adhesive (Clearfil SE Bond; SE), restored with a flowable resin composite (Estelite Flow Quick). Specimens in the demineralized group were incubated for 2 weeks after Streptococcus mutans biofilm formation, while specimens in the control group were incubated for 2 weeks without biofilms. After SS-OCT observation, specimens were cut and examined under confocal laser scanning microscope (CLSM). The lesion depth (LD), interfacial gap depth (GD) and gap length (GL) obtained from SS-OCT and CLSM were analyzed by Pearson's correlation, LD by Independent-samples t-test, GD and GL by Welch t-test, the frequency of specimens with or without gap by Fisher's exact test at the 95% significant level.

RESULTS

Specimens with interfacial gaps in the demineralized group showed significantly higher frequency than that in the control group (p<0.05). There was a significant correlation between SS-OCT and CLSM values of LD, GD and GL (p<0.05). SE showed significantly larger LD of dentin, but less GD and GL of enamel than TS (p<0.05).

SIGNIFICANCE

SS-OCT nondestructively detected demineralization around composite restorations and interfacial gaps created by S. mutans biofilm in this in vitro model.

Monitoring of cariogenic demineralization at the enamel-composite interface using swept-source optical coherence tomography

OBJECTIVES

The aim of this study was to evaluate enamel demineralization at composite restoration margins caused by cariogenic biofilm using swept-source optical coherence tomography (SS-OCT).

METHODS

Sixty round-shaped cavities were prepared on the mid-buccal enamel surface of extracted human molars. The cavities were restored with Estelite Flow Quick flowable composite using either Clearfil SE Bond or Clearfil Tri-S Bond ND bonding agents. Streptococcus mutans suspension was applied to form a cariogenic biofilm on the surface. After 1, 2, or 3 weeks of incubation (n=10), the biofilm was removed to observe the carious demineralization at the cavosurface margins using SS-OCT. The gap along the enamel-composite interface was recorded on each adhesive system. Confirmatory direct observation was accomplished at the same location using confocal laser scanning microscope.

RESULTS

The demineralized enamel around the restorations was observed as a zone of intensified brightness in SS-OCT. The demineralized lesion on the cervical enamel was significantly deeper than that on the occlusal enamel (p<0.05). However, the extension of enamel demineralization at the enamel-composite interface was significantly deeper at the occlusal wall than the cervical wall (p<0.05). The extension in Tri-S Bond ND group was significantly deeper than in SE Bond group (p<0.05). A significant increase in gap formation was found after the extension of demineralization compared with the baseline.

SIGNIFICANCE

The carious demineralization around composite restorations were observed as a bright zone in SS-OCT during the process of bacterial demineralization. SS-OCT appears to be a promising modality for the detection of caries adjacent to an existing restoration.

Assessment of cervical demineralization induced by Streptococcus mutans using swept-source optical coherence tomography

Exposed root surfaces due to gingival recession are subject to biofilm stagnation that can result in caries formation. Cervical enamel and dentin demineralization induced by a cariogenic biofilm was evaluated using swept-source optical coherence tomography (SS-OCT). The cementoenamel junction (CEJ) sections of extracted human teeth were subjected to demineralization for 1, 2, or 3 weeks. A suspension of Streptococcus mutans was applied to form a cariogenic biofilm using an oral biofilm reactor. After incubation, demineralization was observed by SS-OCT. For the analysis of SS-OCT signal, the value of the area under the curve (AUC) of the signal profile was measured. Statistical analyses were performed with 95% level of confidence. Cervical demineralization was displayed as a bright zone in SS-OCT. The demineralization depth of dentin was significantly deeper than that of enamel ([Formula: see text]). Enamel near the CEJ demonstrated a significant increase of AUC over the other enamel region after the demineralization. The gaps along the dentinoenamel junction were additionally observed in SS-OCT. SS-OCT was capable of monitoring the cervical demineralization induced by a cariogenic biofilm and is considered to be a promising modality for the diagnosis of cervical demineralization.

Potentials of mouthwashes in disinfecting cariogenic bacteria and biofilms leading to inhibition of caries

OBJECTIVES

The aim of this study was to compare the effects of certain commercially available mouthwashes on cariogenic bacteria and biofilms, following the acquisition of inhibition potentials of caries.

MATERIALS AND METHODS

Mouthwashes containing I) chlorhexidine gluconate (CHG; 0.0005% w/v), II) benzethonium chloride (BTC; 0.01% w/v), III) an essential oil (Listerine), and IV) povidone-iodine (PVP-I; 0.035% w/v) were tested on planktonic cariogenic bacteria, biofilms, and an ex vivo caries model. Bacterial aliquots were inoculated with each solution separately and vortexed for 10 seconds at room temperature. Bacterial viability was subsequently investigated by fluorescence microscopy (FM) after staining with a BacLight viability kit and the number of colony-forming units (CFUs) was counted. Similarly, mouthwash solutions were applied to artificial cariogenic biofilms, and bacterial viability of the biofilms was investigated as stated above. Inhibition potentials of two selected mouthwashes of carious lesions were investigated using biofilm-induced caries and a secondary caries model. In all steps, a phosphate-buffered saline (PBS) solution was included as a control.

RESULTS

Planktonic cariogenic bacteria and bacteria embedded in biofilms were killed in remarkably large numbers with Listerine and PVP-I treatment compared to PBS and other gargles. CFU counts also showed significant reduction after treatment with Listerine and PVP-I compared to other solutions (P<0.05). Listerine also displayed significant (P<0.05) inhibition effects in preventing the progression of demineralization.

CONCLUSION

Bactericidal potencies of the mouthwashes varied significantly, suggesting that mouthwashes like Listerine can be useful for the prevention of caries and secondary caries.

Intraoral pH measurement of carious lesions with qPCR of cariogenic bacteria to differentiate caries activity

OBJECTIVES

A low pH environment is created by cariogenic bacteria. This study was aimed to measure pH of carious lesions intraorally using a micro-pH sensor, and assess predominant acid-producing cariogens by qPCR to differentiate caries activities.

METHODS

103 dentine lesions classified as active or arrested caries based on the clinical and radiological examinations were collected from patients after intraoral measurement of the lesion surface pH using a micro-pH sensor. Quantitative detection of genomic DNA copies of target cariogenic bacteria (mutans streptococci and Lactobacillus spp.) in each lesion was performed using real-time PCR. Correlation between the pH ranges and the number of bacterial species was examined by Spearman test.

RESULTS

50 samples were diagnosed as active and 53 as arrested lesions. Statistically significant difference was observed on average surface pH value between active and arrested lesions (p<0.05). Prevalence of Lactobacillus spp. was higher in active lesions than in arrested lesions (76% vs. 58% of samples, respectively). When the carious lesions were categorised into four different pH ranges (up to 5.5, from 5.6 to 5.8, from 5.9 to 6.1 and 6.2 or above), increased prevalence of Lactobacillus spp. was observed with decrease of pH levels. A significant negative relationship was found between pH value and number of Lactobacillus spp. (r=-0.209, p<0.05) but no such correlation was found for mutans streptococci.

CONCLUSIONS

Intraoral pH measurement might be clinically useful to determine acidity of the local environment of carious lesions as one aspect of the caries activity assessment.

CLINICAL SIGNIFICANCE

The population of certain bacteria may indicate activity of carious lesions. Intraoral pH measurement of the carious lesions using a micro-pH sensor may be a clinically feasible method for assessment of lesion acidity.

Effects of electrodeposited poly(ethylene glycol) on biofilm adherence to titanium

Protein-resistant coatings have been studied for inhibiting biofilm formation on implant devices. In this study, titanium (Ti) surfaces were biofunctionalized with poly(ethylene glycol) (PEG) by electrodeposition and were evaluated as biofilm substrates under an oral simulated environment. Streptococcus gordonii, an early colonizer of oral biofilms, was inoculated on Ti and PEG-electrodeposited Ti (PEG-Ti) surfaces and was analyzed quantitatively and topographically. Streptococcus mutans supplemented with sucrose, a late colonizer mainly found in dental plaque, was also used to form biofilms on the surfaces of Ti and PEG-Ti for 20 h followed by sonication as a means of detaching the biofilms. The results indicated that the attachment of S. gordonii on PEG-Ti surfaces was inhibited compared with Ti, and the S. mutans biofilm was easier to be detached from the surface of PEG-Ti than that of Ti. Moreover, the presence of PEG electrodeposited on Ti surface inhibited salivary protein adsorption. The degree of detachment of biofilms from PEG-Ti was associated with the inhibition of the salivary protein adsorption, suggesting weak basal attachment of the biofilms to the electrodeposited surfaces. Therefore, controlling protein adsorption at the initial stage of biofilm formation may be an effective strategy to protect metal surfaces from bacterial contamination not only in dental manipulations but also in orthopedic applications.

Preservation in the liquid media produces alterations in enamel surface properties

OBJECTIVE

The aim of the study was to elucidate any alterations in nanomechanical properties and structural integrity of enamel surfaces after preservation in different liquid media.

METHODS

The nanohardness and modulus of elasticity of bovine enamel blocks were measured before (control) and after storage in all of the following liquid media: human pooled saliva, physiological saline (NaCl), Deionized water (Milli-Q water) and phosphate buffered saline (PBS) for 1, 7, 14 and 30 days. Control and the 30 days preserved samples were examined by scanning electron microscopy (SEM). Data were analysed by one-way ANOVA and Dunnett T(3) test.

RESULTS

Hardness and modulus of elasticity of enamel in saliva up to 14 days showed no significant decrease compared to controls. In the case of PBS, both hardness and modulus did not change up to 30 days. The hardness values of Milli-Q water (12.06%) and NaCl (14.19%) samples were reduced significantly after just for 1 day and after 30 days were reduced to 55.59% and 61.18%, respectively. The Young's modulus of NaCl samples showed significant reduction (8.35%) after 1 day, but not for Milli-Q water samples. From 7 to 30 days, significant reductions for both samples were detected. SEM photomicrographs of samples in saliva showed widening of the inter-prismal space, while in PBS samples the structural damage was less. In the Milli-Q water group, prominent structural damage was observed and in case of NaCl, the enamel prisms were eroded.

CONCLUSIONS

Human saliva and PBS are better for short term preservation of enamel samples compared to NaCl and Deionized water.

Effects of root dentin surface coating with all-in-one adhesive materials on biofilm adherence

OBJECTIVES

Sealing of exposed root dentinal surfaces with adhesive materials is expected to be a promising approach for preventing root dentin caries. The aim of this study was to evaluate the effects of surface coating with all-in-one adhesives on inhibiting Streptococcus mutans biofilm attachment.

MATERIALS AND METHODS

Bovine root dentin was cut and ground with #600-grit SiC paper. Each of the three all-in-one adhesives, Hybrid Bond (HB), Reactmer Bond (RB) or Shake One (SO) was single-coated on the dentin surfaces according to the manufacturers' instructions. The dentin surface without coating served as the control. The surface roughness of the coated and non-coated dentin surfaces was recorded by means of laser microscope measurements. S. mutans artificial biofilms were then grown on the surface of each specimen in a microcosm for 20h. The amounts of bacteria and water insoluble glucan in the retained biofilm on the surface of the specimens were measured. All numerical data were statistically analyzed using one-way ANOVA & Tukey's HSD (p<0.05).

RESULTS

All of the coated groups showed significantly lower susceptibility to biofilm attachment compared with the non-coated root dentin (p<0.05). Among the coated groups, SO showed the lowest susceptibility for biofilm formation.

CONCLUSIONS

Three all-in-one adhesive materials could be effective for root surface coating. A fluoride-releasing adhesive, SO demonstrated the strongest potentiality in resisting biofilm formation.

Effect of surface characteristics on adherence of S. mutans biofilms to indirect resin composites

The purpose of this study was to evaluate the adherence of biofilms to the surfaces of two indirect resin composites, Estenia C&B and Gradia. Slabs were prepared from the materials, and then either ground with 800-grit silicon carbide paper or polished with diamond pastes up to 1 microm. Artificial biofilms of Streptococcus mutans were grown on the composite slabs in an artificial mouth system for 20 hours. Thereafter, the amounts of retained biofilm on the surfaces were measured after sonication. Surface characteristics of the resins--such as surface roughness, amount of residual monomers, and distribution of filler particles--were examined. Two-way ANOVA revealed that the amount of retained biofilm varied (p<0.05) according to the composition and surface roughness of the material. In particular, biofilm adherence was lowest on Estenia C&B slabs when polished with diamond pastes up to 1 microm. It was thus concluded that the surface roughness and composition of a resin composite influenced biofilm adherence.

Surface properties of resin composite materials relative to biofilm formation

The surface properties of three different resin composite materials which influence Streptococcus mutans biofilm formation were evaluated using an artificial mouth system (AMS). Specimens were prepared from Clearfil AP-X, Grandio, and Reactmer Paste, and each material was divided into two groups: (1) surface was ground with 800-grit silicon paper (SiC#800); or (2) surface was polished with up to 1- microm diamond paste (DP1 microm). Biofilms were grown on the surface of each specimen for 20 hours, and then subjected to vortex agitation followed by measurement of retained biofilms. Surfaces with retained biofilms were also inspected by SEM. Significant differences were detected in surface roughness (Ra) between the two polishing conditions for all materials. The quantity of retained biofilm was significantly less (p < 0.05) on Clearfil AP-X DP 1 microm than on Clearfil AP-X SiC#800. With Reactmer Paste, their surfaces registered the lowest amount of retained biofilm--but there were no significant differences between the two polishing conditions. In conclusion, polishing did not render all resin composites equally resistant to biofilm formation.

Phase II study of gefitinib and docetaxel for patients (pts) with advanced pancreatic adenocarcinoma (APC) progressing after first-line therapy. Final results

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Background: Gemcitabine is the standard-of-care for APC; the epidermal growth factor receptor (EGFR) inhibitor erlotinib is sometimes added to initial therapy. Pre-clinical data supports the addition of the EGFR inhibitor gefitinib to docetaxel, an agent with activity in APC. Because there is no standard treatment after gemcitabine failure, this combination was examined in a phase II study. Methods: Pts were required to have APC and have failed one prior treatment regimen; EGFR over-expression was not required. The initial docetaxel dose was 75 mg/m2 on day one every 21 days . Due to febrile neutropenia in 8 of 18 pts, the dose was reduced to 60 mg/m2. Gefitinib 250 mg/day orally was given continuously. Accrual of 41 pts was planned in a one-stage design to identify a targeted 50% improvement in median survival from 3.5 to 5.3 months (mo) by one-sided log-rank test (80% power, a = 0.05). Results: Forty five pts met eligibility and signed consent; 41 pts received treatment and were evaluable. Pt characteristics: 68% male, median age 63 yrs. (range 47 - 82). ECOG performance status (PS) 0 - 1 in all pts, except for 3 with PS of 2. Common treatment-related Grade 3 - 4 toxicities were: febrile neutropenia / infection in 11 pts (27%), with most events occurring at docetaxel dose of 75 mg/ m2 (8 of 18 pts); fatigue (7%), nausea (7%), diarrhea (5%) and vomiting (2%). Only 3 pts discontinued treatment due to toxicities and more than 2 cycles were administered to 40% of patients. The median survival was 4.7 mo (95% CI 2.9 - 5.7 mo). Time to progression was 1.8 months. There was one partial response (PR) and stable disease (SD) in 14 pts. Conclusion: The combination of gefitinib (250 mg/d) and docetaxel (60 mg/ m2) had evidence of some efficacy with one PR and SD in 14 pts. The median survival was 4.7 mo, somewhat lower than our intended target (5.3 mo). The tolerability and feasibility of second-line therapy for APC was demonstrated, and results of this study can be used as a benchmark to evaluate novel therapies in subsequent studies. (Supported by Astra Zeneca Pharmaceuticals)

No significant financial relationships to disclose.

Effect of Resin Coating on Dentin Bonding of Resin Cement in Class II Cavities

This study was designed to evaluate the efficacy of resin coating on the regional microtensile bond strength (MTBS) of a resin cement to the dentin walls of Class II cavities. Twenty mesio-occlusal cavities were prepared in human molars. In 10 cavities, a resin coating consisting of a self-etching primer bonding system, Clearfil SE Bond, and a low-viscosity microfilled resin, Protect Liner F, was applied. The other 10 teeth served as a non-coating group. After impression taking and temporization, they were kept in water for one day. Composite inlays were then cemented with a dual-cure resin cement, Panavia F 2.0, and stored in water for one day. Thereafter, MTBSs were measured. Two-way ANOVA (p=0.05) revealed that the MTBS of resin cement to dentin was influenced by resin coating, but not by regional difference. In conclusion, application of a resin coating to the dentin surface significantly improved the MTBS in indirect restorations.

Phase II study of gefitinib and docetaxel as salvage therapy in patients (pts) with advanced pancreatic adenocarcinoma (APC)

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Background: There is no standard-of-care second-line chemotherapy for APC. The combination of docetaxel and gefitinib, an inhibitor of epidermal growth factor receptor (EGFR) shows enhanced preclinical activity compared to docetaxel alone. Docetaxel alone has activity in APC, and this phase II trial is designed to evaluate the combination. The primary endpoint is survival with an accrual goal of 45 patients to detect an improvement to 5.25 months (mo) in median survival time by one-sided log-rank test at level α = 0.05. Methods: Patients with APC and one prior chemotherapy regimen are eligible for study; EGFR over-expression is not required. Gefitinib is administered at the dose of 250 mg/day orally without interruption. The initial dose of docetaxel was 75 mg/m2 every three weeks (one cycle), but was reduced to 60 mg/m2 due to a high incidence of febrile neutropenia. Results: 31 pts, all with prior gemcitabine therapy, have been enrolled on study to date, with 26 evaluable for toxicity. Patient characteristics: 62% male; 92 % with ECOG performance status 0/1, 8% ECOG of 2; median age 64 years (range 47–82 years). The best response is stable disease (5 pts), median cycles administered 2 (range 1–12). Thus far the median survival time is 4.4 mo, with median time to progression of 2.5 mo. Grade (G) 3/4 febrile neutropenia occurred in 8 out of 18 pts treated at the 75 mg/m2 dose of docetaxel; none has been seen with the 60 mg/m2 dose. Other G 3/4 adverse events include: diarrhea (3.8%), rash (7.7%), constitutional symptoms (11.5%), and nausea (11.5%). Conclusion: The combination of gefitinib and docetaxel at 60 mg/m2 is tolerable, with interim results showing a median survival time of 4.4 mo at this point. If the protocol’s goal of median survival time of 5.25 mo is met upon study completion, the combination may be worthy of further investigation.

No significant financial relationships to disclose.

E2f1 mutation induces early onset of diabetes and Sjögren's syndrome in nonobese diabetic mice

E2f1 is an important regulator of T cell proliferation, differentiation, and apoptosis that controls the transcription of a group of genes that are normally regulated at the G1 to S phase transition in the cell cycle. Insulin-dependent diabetes mellitus (IDDM) and Sjogren's syndrome (SS) are highly regulated autoimmune diseases that develop spontaneously in NOD mice. The aim of the present in vivo study was to explore the functional importance of the E2f1 molecule in IDDM and SS, in the context of whole animal physiology and pathophysiology, using E2f1-deficient NOD mice. For the experiment, we produced NOD mice homozygous for a nonfunctional E2f1 allele onto a NOD background. E2f1-deficient NOD mice developed an early and increased onset of diabetes as compared with their littermates. These mice also exhibited a defect in T lymphocyte development, leading to excessive numbers of mature T cells (CD4+ and CD8+), due to a maturation stage-specific defect in the apoptosis of thymocytes and peripheral T cells. We also found that they also exhibited a more rapid and increased entry into the S phase following antigenic stimulation of spleen cells and thymocytes in vitro. Furthermore, E2f1-deficient mice showed a profound decrease of immunoregulatory CD4+CD25+ T cells, while the spleen cells of NOD mice lacking E2f1 showed a significant increase of the proinflammatory cytokine IFN-gamma following antigenic stimulation in vitro. Consistent with these observations, E2f1 homozygous mutant NOD mice were highly predisposed to the development of IDDM and SS.

Establishment of an animal model using recombinant NOD.B10.D2 mice to study initial adhesion of oral streptococci

An oral biofilm is a community of surface-attached microorganisms that coats the oral cavity, including the teeth, and provides a protective reservoir for oral microbial pathogens, which are the primary cause of persistent and chronic infectious diseases in patients with dry mouth or Sjögren's syndrome (SS). The purpose of this study was to establish an animal model for studying the initial adhesion of oral streptococci that cause biofilm formation in patients with dry mouth and SS in an attempt to decrease the influence of cariogenic organisms and their substrates. In nonobese diabetogenic (NOD) mice that spontaneously develop insulin-dependent diabetes mellitus (IDDM) and SS, we replaced major histocompatibility complex (MHC) class II (A(g7) E(g7)) and class I D(b) with MHC class II (A(d) E(d)) and class I D(d) from nondiabetic B10.D2 mice to produce an animal model that inhibited IDDM without affecting SS. The adhesion of oral streptococci, including Streptococcus mutans, onto tooth surfaces was then investigated and quantified in homologous recombinant N5 (NOD.B10.D2) and N9 (NOD.B10.D2) mice. We found that a higher number of oral streptococci adhered to the tooth surfaces of N5 (NOD.B10.D2) and N9 (NOD.B10.D2) mice than to those of the control C57BL/6 and B10.D2 mice. On the basis of our observation, we concluded that these mouse models might be useful as animal models of dry mouth and SS for in vivo biological studies of oral biofilm formation on the tooth surfaces.

RGD motif enhances immunogenicity and adjuvanicity of peptide antigens following intranasal immunization

The use of peptides for various aspects of medical science has been a significant advance. Peptide-based vaccines are promising, but weak immunogenic potency is impeding the clinical application. We have remarkably enhanced the immunogenicity of peptide antigens by addition of motifs that bind to cell attachment proteins, such as arginine-glysine-aspartate (RGD), to the amino acid sequence. The modified peptides induced antigen-specific serum antibodies by intranasal immunization without adjuvants. RGD, an integrin-binding motif was the strongest, among several molecules tested in this experiment, giving an average of 10 times enhancement of antibody titers when incorporated into several peptide antigens. The peptides also acted as an efficient adjuvant following the intranasal immunization with protein antigens. Our data support the feasibility of developing peptide vaccines and peptide adjuvants for intranasal vaccination.

Feasibility of eradication of mutans streptococci from oral cavities

OBJECTIVES

Dental caries prevention programs using chlorhexidine (CHX) have been proposed, but CHX's effect in reducing levels of mutans streptococci (S. mutans and S. sobrinus) appears to last for only a few months. The aim of this study was to attempt to eradicate mutans streptococci from the oral cavity using intensive professional mechanical tooth cleaning (PMTC) and topical application of CHX in custom-made trays.

METHODS

Seven adult dentate subjects participated in this study (mean age 53.7+/-5.6, age range 46 to 62, mean DMFT, 9.1+/-4.2). For each subject, PMTC was carried out eight times within ten days. After each PMTC, 1% CHX was applied twice to the tooth surface using custom-made trays. In addition, as home treatment, subjects were required to carry out tooth brushing three times a day, and apply 0.2% CHX in custom trays after brushing in the morning and evening. In addition, subjects rinsed with 0.2% CHX solution after lunch. Salivary levels of mutans streptococci were evaluated using Dentocult-SM at baseline and on days 9, 20, 70, 120.

RESULTS

Mutans streptococci were eradicated by day 120 from 4 of the 7 seven subjects participating in this study. Those 3 subjects still harboring mutans streptococci exhibited deep periodontal pocketing.

CONCLUSIONS

Eradication of mutans streptococci from the oral cavity is feasible using a combination of CHX application in custom-made trays and intensive PMTC.

Anti-hyperalgesic effect of octreotide in patients with irritable bowel syndrome

BACKGROUND

Octreotide has been found to be beneficial in the treatment of chronic pain, although the mechanisms underlying its therapeutic effect are incompletely understood.

AIMS

To assess the effect of octreotide on perceptual responses to rectal distension in irritable bowel syndrome patients and healthy controls at baseline and following the experimental induction of rectal hyperalgesia.

METHODS

In study 1, rectal perception thresholds for discomfort were determined in seven irritable bowel syndrome patients and eight healthy controls on three separate days using a computer-controlled barostat. Subjects received saline, low-dose and high-dose octreotide in a random double-blind fashion. In study 2, perceptual responses to rectal distension were obtained in nine irritable bowel syndrome patients and seven controls before and after repetitive high-pressure mechanical sigmoid stimulation.

RESULTS

Octreotide increased the discomfort thresholds in irritable bowel syndrome patients, but not in controls, without changing rectal compliance. Repetitive sigmoid stimulation resulted in decreased rectal discomfort thresholds in the patient group only. In irritable bowel syndrome patients, octreotide prevented the sensitizing effect of repetitive sigmoid stimulation on rectal discomfort thresholds.

CONCLUSIONS

Octreotide effectively increased discomfort thresholds in irritable bowel syndrome patients, but not in controls, at baseline and during experimentally induced rectal hyperalgesia. These findings suggest that octreotide exerts primarily an anti-hyperalgesic rather than analgesic effect on visceral perception.

Assessment of oral transmission using cell-free human immunodeficiency virus-1 in mice reconstituted with human peripheral blood leucocyte

Oral-genital contact is one of the risk factors for the transmission of human immunodeficiency virus (HIV) in adults. In recent reports, oral exposure to simian immunodeficiency virus (SIV) was found to have important implications for the achievement of mucosal transmission of HIV in a rhesus monkey animal model. In the present study, we aimed first to establish a small animal model which did not develop tonsils suitable for HIV oral mucosa transmission, using non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice and NOD/SCID B2m(null) mice grafted with human peripheral blood leucocytes (hu-PBL) and stimulated with interleukin (IL)-4, and second to investigate whether oral exposure to cell-free R5 and X4 HIV-1 could lead to oral transmission of HIV through intact or traumatized mucosal tissues in humanized mice. Both low and high concentrations of cell-free R5 and X4 viruses failed to cause oral transmission with or without trauma in hu-PBL-NOD/SCID and NOD/SCID Beta2m(null) mice, which presented a number of CD4+ cells in gingival tissues and oral cavities with or without tissue injury. The present results show that IL-4-administrated NOD/SCID B2m(null) mice are useful as a small-humanized model for the study of HIV oral infection, which may help to define the window of opportunity for oral transmission by the HIV virus in animal model experiments.

Role of stromal-cell derived factor-1 in the development of autoimmune diseases in non-obese diabetic mice

The chemokine stromal-cell derived factor-1 (SDF-1) controls maturation, trafficking, and homing of certain subsets, lymphoid cells including immunogenic B and T cells, as a ligand of the CXCR4 chemokine receptor. Insulin-dependent diabetes mellitus (IDDM) and Sjögren's syndrome (SS), both highly regulated autoimmune diseases, develop spontaneously in non-obese diabetic (NOD) mice. To investigate the role of SDF-1 in the development of autoimmune diseases, we injected groups of NOD female mice with antibodies to SDF-1 (anti-SDF-1), which resulted in a 30% reduction of diabetes up to 30 weeks of age, delayed average diabetes onset by 10 weeks, and suppressed insulitis. Autoimmune sialoadenitis was evident in anti-SDF-1-injected mice (SDF-1-Ig group) at the same level as in all groups of mice, whether injected with non-specific antibodies or not. In addition, in the SDF-1-Ig group, a greater number of immunoglobulin M (IgM)- IgD- B220(low) CD38+ CD43+ CD23- progenitor B cells and IgM+ IgD+ B220(high) CD43- CD38+ CD24+ CD23+ mature B cells remained in the bone marrow, whereas infiltration of mature IgM+ B cells was less extensive in peripheral tissues. Our results suggested that anti-SDF-1 antibodies injection was effective in inhibiting diabetes and insulitis without affecting autoimmune sialoadenitis or SS in NOD mice. SDF-1 may be an essential chemokine for trafficking and migration of autoreactive B cells in the development of diabetes.

Effects of human interleukin-18 and interleukin-12 treatment on human lymphocyte engraftment in NOD-scid mouse

NOD/LtSz-prkdc(scid)/prkdc(scid) (non-obese diabetic-severe combine immunodeficiency; NOD-scid) mice grafted with human peripheral blood lymphoid cells have been used as an in vivo humanized mouse model in various studies. However, cytotoxic human T cells are induced in this model during immune responses, which gives misleading results. To assist in grafting of human lymphocytes without the induction of cytotoxic human T cells, we investigated the effects of T helper type 1 (Th1) and Th2 cytokines on human lymphocyte grafting and migration, as well as the production of immunoglobulin deposited in glomeruli and human immunodeficiency virus-1 (HIV-1) infection using NOD-scid mice. Administration of interleukin-18 (IL-18) and IL-12 enhanced the grafting of human CD4+ and CD8+ T cells in the mice, whereas co-administration prevented grafting due to interferon-gamma-dependent apoptosis. Immunoglobulin A (IgA) deposits were observed in mice treated with IL-18 alone, but not in those given phosphate-buffered saline, IL-12 alone, or IL-18 + IL-12. A high rate of HIV infection was also observed in the IL-18-treated group. Together, these results indicate that IL-18 may be effective for the grafting and migration of CD4+ and CD8+ T cells, except for the induction of apoptosis and regulation of class-switching IgA. IL-18-administered NOD-scid mice provide a useful small humanized model for the study of HIV infection and IgA nephropathy.

Inhibitory effects of MoAbs against a surface protein antigen in real-time adherence in vitro and recolonization in vivo of Streptococcus mutans

A surface protein antigen (PAc) of Streptococcus mutans, particularly the A-region of the molecule, has been reported to interact with salivary components on the tooth surface. It might be a candidate antigen inducing the production of antibodies against the adherence of S. mutans to the tooth surface. We investigated the effects of monoclonal antibodies (MoAbs) obtained by immunization of synthetic PAc peptides that completely correspond to the amino acid sequence of part of the A-region. These MoAbs recognize several core B-cell epitopes in the sequence. Two (KH5 and SH2) of these antibodies reacted with both S. mutans and Streptococcus sobrinus, but not with Streptococcus sanguis, Streptococcus salivarius, Porphyromonas gingivalis or Lactobacillus casei. They clearly inhibited the real-time adherence of S. mutans to salivary components in a biosensor. KH5, which showed a real-time inhibition (71%), also significantly prevented the recolonization of S. mutans on the tooth surface in rats. These results suggested that the core B-cell epitope (-Y---L--Y----) recognized by KH5 was the essential sequence in the antigenic epitopes of PAc protein recognized specifically by the inhibitory antibody. Therefore, the amino acid residues were found to be important in the initial attachment of S. mutans to the tooth surface. These results provide for the mechanism of PAc molecule in the initial attachment of S. mutans on the tooth surface and more effective designs for the removal of S. mutans and S. sobrinus from the oral cavity.

Impact of recombinant human bone morphogenetic protein-2 on residual ridge resorption after tooth extraction: an experimental study in the rat

Residual ridge resorption begins following tooth extraction and continuously reduces alveolar bone volume, potentially creating a significant problem in dental implant treatment. In this study, the role of recombinant human bone morphogenetic protein-2 (rhBMP-2) in residual ridge resorption after tooth extraction was investigated. A polylactic acid/polyglycolic acid copolymer-coated gelatin sponge carrier was implanted with or without rhBMP-2 (1 microg) in the mesial root sockets after removal of maxillary first molars in male Wistar rats. Fine structural and histomorphologic analyses were conducted 3 to 84 days after implantation. Direct bone formation was first observed after 5 days on the rhBMP-2 side, which was transformed into cortical alveolar ridge with a smooth periosteal layer by 84 days, whereas the control side displayed slower healing. Bone histomorphometry revealed greater total bone area and increased bone height after 14, 28, 56, and 84 days on the rhBMP-2 side compared to the control side, and differences were significant after 14, 28, and 56 days. Larger numbers of proliferating cells and densely populated differentiating mesenchymal cells were observed on the rhBMP-2 side than on the control side in the early stage, and chondrogenesis was not observed. The findings indicate that rhBMP-2 may stimulate proliferation and differentiation of mesenchymal cells in the rat maxillary root socket to preserve cortical bone volume in the socket without any evidence of chondrogenesis.

Perceptual responses in patients with inflammatory and functional bowel disease

BACKGROUND AND AIMS

Enhanced visceral sensitivity following a transient inflammatory process in the gut has been postulated as an aetiological mechanism of irritable bowel syndrome (IBS). In this study we compared perceptual responses to rectosigmoid distension in patients with mild chronic inflammation of the rectum (ulcerative colitis (UC)) and patients without mucosal inflammation (IBS) to determine if chronic low grade mucosal inflammation may be a plausible explanation for rectosigmoid hypersensitivity reported in both IBS and UC patients.

METHODS

UC disease activity was quantified using activity index scores. Perception thresholds for discomfort during rectosigmoid distension were compared between 11 UC patients with quiescent or mild disease activity, 18 IBS patients, and 13 healthy controls.

RESULTS

Although UC activity index scores negatively correlated with perceptual thresholds for discomfort (r=-0.76, p=0.016), UC patients had higher discomfort thresholds compared with IBS patients and controls before (p=0.02) and after (p<0.001) a noxious sigmoid conditioning stimulus.

CONCLUSIONS

Rectal perception was attenuated in UC but enhanced in IBS. In chronic mild inflammation, activation of antinociceptive mechanisms may prevent the development of visceral hyperalgesia. Low grade mucosal inflammation alone is unlikely to be responsible for symptoms in functional gastrointestinal disorders.

Audio and visual stimulation reduces patient discomfort during screening flexible sigmoidoscopy

OBJECTIVE

Despite current recommendations calling for regular screening flexible sigmoidoscopies over the age of 50, only a small percentage of the population have regular examinations. Improving patient tolerance of flexible sigmoidoscopies could therefore increase patient compliance with these recommended guidelines. The aim of this study was to determine whether audio and visual stimulation reduces discomfort during flexible sigmoidoscopy and whether the effects of the stimulation are secondary to distraction.

METHODS

A total of 37 patients undergoing routine screening flexible sigmoidoscopy were randomized to receive no intervention, audio stimulation alone, or audio and visual stimulation. Patient discomfort ratings and affect states were measured prior to and immediately following flexible sigmoidoscopy using a visual analogue scale and the Stress Symptom Ratings (SSR) ratings.

RESULTS

Patients receiving audio and visual intervention had lower abdominal discomfort ratings (7.1 +/- 1.4) than patients receiving audio stimulation (9.5 +/- 1.3) or no intervention (10.8 +/- 1.6) (p < 0.05). Patients receiving audio and visual intervention also had higher arousal (7.3 +/- 0.4) and attention (9.2 +/- 0.2) ratings than patients receiving no intervention (6.1 +/- 0.4 and 6.2 +/- 0.7, respectively) (p < 0.05). Anxiety and anger ratings, on the other hand, were significantly lower in patients receiving audio and visual intervention (2.5 +/- 0.4, 1.4 +/- 0.3, respectively) than patients receiving no intervention (4.4 +/- 0.6, 3.6 +/- 0.7).

CONCLUSION

Audio and visual stimulation reduces abdominal discomfort associated with flexible sigmoidoscopy. This effect appears to be due to distraction.

Off-site dental evaluation program for prospective bone marrow transplant recipients

The authors evaluated the usefulness of an off-site dental evaluation program for bone marrow recipients. This evaluation packet enabled patients scheduled for bone marrow transplants to be evaluated by, and receive any treatment from, their own dentist rather than a dentist at the transplant center. The program generally was effective in achieving its goals and was well-accepted by patients and dentists alike.