Treatment of developmental defects of enamel

Developmental defects of enamel are encountered daily in our dental practice. The management of enamel hypomineralized lesions may be challenging, especially as esthetic concern around the young population is increasing. Resin infiltration, a new technique firstly proposed to halt caries progression in the posterior segment, showed a strong positive esthetic effect in the treatment of developmental defects with different etiologies. Future in-vivo studies are needed to evaluate the longterm color stability, in order to provide a strong clinical recommendation.

The Effect of Resin Infiltration on the Progression of Proximal Caries Lesions: A Randomized Clinical Trial

OBJECTIVE

The aim of this clinical trial was to assess the effect of resin infiltration on the progression of proximal caries lesions.

SUBJECTS AND METHODS

Forty-one patients, aged between 15 and 33 years, with 2 or more non-cavitated proximal caries lesions were included. In 41 of the adolescent and young adults, 45 pairs of proximal lesions with radiological extension into the inner and outer half of the enamel, or into the outer third of the dentin, were randomly allocated to the test groups (resin infiltration application + fluoridated toothpaste and flossing use) or to the control group (fluoridated toothpaste and flossing use). Standardized geometrically aligned digital bitewing radiographs were obtained using individual biting holders. The radiographic progression of the lesions was assessed after 1 year by digital-subtraction radiography. The McNemar test was used for statistical analysis.

RESULTS

In the test group 1/45 of the lesions (2.2%) and in the control group 9/45 of the lesions (20%) showed progression. The caries progression rate of the control group was significantly higher than that of the test group (p < 0.05).

CONCLUSIONS

Resin infiltration of proximal caries lesions is effective in reducing progression of the lesion.

Development of a novel resin-based dental material with dual biocidal modes and sustained release of Ag+ ions based on photocurable core-shell AgBr/cationic polymer nanocomposites

Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag⁺ ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag⁺ ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag⁺ ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations.

Streptococcus mutans adherence and biofilm formation on experimental composites containing dicalcium phosphate dihydrate nanoparticles

This study aimed at evaluating bacterial adhesion and biofilm formation on resin-based composites (RBC) including dicalcium phosphate dihydrate nanoparticles (nDCPD).

METHODS

Specimens were prepared from experimental RBCs with BisGMA/TEGDMA resin matrix including 20 vol% of either nDCPD (nDCPD-RBC), TEGDMA-functionalized nDPCD (F-nDCPD-RBC) or silanized silica (SiO₂-RBC). Neat resin blend (control-Resin), conventional nanohybrid RBC (control-RBC) and human enamel were used for reference. Characterization of the specimens included surface roughness (SR), surface free energy (SFE), chemical surface composition (EDS, XPS), and buffering ability of a pH = 4.00 solution. Streptococcus mutans adherence was assessed after 2 h; biofilm formation was simulated for 48 h using a bioreactor. Adherent, viable biomass was determined using tetrazolium salt assay (MTT).

RESULTS

nDCPD-RBC yielded highest roughness and showed higher polar and lower disperse component to total SFE. EDS and XPS indicated higher amounts of calcium and phosphate on the surface of nDCPD-RBC than on F-nDCPD-RBC. nDCPD buffered the acidic solution to 5.74, while functionalization almost prevented buffering (pH = 4.26). F-nDCPD-RBC reduced adherence and biofilm formation in comparison to nDCPD-RBC. Regardless of functionalization, biofilm formation on nDCPD-containing RBCs was not significantly different from SiO₂-RBC. Control-Resin, control-RBC, and enamel surfaces showed similar adherence values as F-nDCPD-RBC, but lower biofilm formation compared to both nDCPD-containing RBCs. In conclusion, the incorporation of nDCPD did not minimize S. mutans adherence and biofilm formation as a function of the materials´ surface properties. However, results observed for the buffering capacity indicated that optimized formulations of biomimetic RBCs may be useful for modulating their interaction with microorganisms.

Randomised Clinical Trial on Resin Infiltration and Fluoride Varnish vs Fluoride Varnish Treatment Only of Smooth-surface Early Caries Lesions in Deciduous Teeth

PURPOSE

To clinically evaluate the effectiveness of resin infiltration in conjunction with fluoride varnish treatment vs fluoride varnish treatment alone on facial smooth-surface caries lesions in deciduous teeth.

MATERIALS AND METHODS

This randomised clinical trial was conducted in 419 children aged 18-71 months with at least two active smooth-surface caries lesions in deciduous teeth (ICDAS II score 2). Eighty-one participants met the inclusion criteria and were allocated to one of the two treatment groups: resin infiltration and fluoride varnish (RI+FV) (n = 41) and fluoride varnish only (FV) (n = 40). The prevalence of treated white spot lesions (WSL) was scored. Fluoride varnish was applied in both groups every 3 months for a year.

RESULTS

The mean baseline age of children was 3.8 ± 1.3 years. The effectiveness of resin infiltration measured as the percentage of children who did not present any progression of the treated lesions amounted to 43.1%. After one year, 92.1% of the infiltrated lesions (RI+FV) and 70.6% of the FV lesions had not progressed (p < 0.001).

CONCLUSION

Resin infiltration in conjunction with fluoride varnish treatment of early facial smooth-surface caries lesions in deciduous teeth is superior to fluoride varnish treatment alone for reducing lesion progression.

Novel Injectable and In situ Curable Glycolide/Lactide Based Biodegradable Polymer Resins and Composites

Novel in situ polymerizable liquid three-arm biodegradable oligomeric polyesters based upon glycolic acid (GA), L-lactic acid (LLA), and their copolymers are synthesized and characterized. Injectable and in situ curable polymer neat resins and their composites formulated with bioabsorbable beta-tricalcium phosphate are prepared at room temperature using photo- and redox-initiation systems, respectively. The cured neat resins show the initial compressive yield strength (YCS, MPa), modulus (M, MPa), ultimate compressive strength (UCS, MPa), and toughness (T, kN mm), ranging from 4.0 to 20.1, 201.5 to 730.2, 82.7 to 310.5, and 1.02 to 3.93. The cured composites show the initial YCS, M, UCS and T, ranging from 27.7 to 56.4, 1440 to 4870, 81.6 to 158.9, and 0.94 to 1.97. Increasing GA/LLA ratio increases all the initial compressive strengths of both neat resins and composites. Increasing filler content increases YCS and M but decreases UCS and T. A diametral tensile strength test shows the same trend as a compressive strength test. There seems to be an optimal flexural strength for the composite at the filler content around 43%. An increasing molar ratio increases curing time but decreases the degree of conversion (DC). An increasing filler content increases curing time but decreases exotherm and DC. During the course of degradation, all the materials show a burst degradation behavior within 24 h, followed by an increase in CS. The poly(glycolic acid) neat resin completely loses its strength at around Day 45. The composites completely lose their strengths at different time intervals, depending on their molar ratio and filler content. The degradation rate is found to be molar ratio and filler-content dependent.

Success Rate of Treatments Provided for Early Childhood Caries under General Anesthesia: A Retrospective Cohort Study

PURPOSE

The purpose of this study was to assess the success rate of various treatments provided under general anesthesia for early childhood caries (ECC) over three-year follow-up period.

METHODS

ECC children no older than 72 months at the time of dental surgery, who had completed a three-year follow-up, were included. The success rate of every treatment was evaluated. The longevity of each treatment and significant factors associated with failures were assessed.

RESULTS

A total of 818 children (55.8 percent were males with a mean age of 46.2±13.4 months old) were included. Of these, 32.9 percent had restored teeth that required further treatment during the three-year follow-up. Amalgam restorations and stainless steel crowns (SSCs) showed significantly longer survival than composite restorations in all types of restorations (P<.05). The survival rate of both indirect pulp capping and pulpotomies were the same (P=0.234), and they were significantly higher than that for pulpectomies (P=0.001, P=0.039, respectively). The lower lingual holding arch (LLHA) had a significantly lower survival rate than other space maintainers (P<0.05).

CONCLUSIONS

SSCs and amalgam restorations were clinically more successful and had better survival times than composite restorations. The survival rate for the LLHA was low compared to other space maintainers.

Resin infiltration of early carious lesion in early childhood: a case report

The treatment of white-spot lesions in infants and young children with early childhood caries is a challenge. The ideal management of the disease and subsequent remineralization of the lesions depend on the family's commitment to dietary behavior modifications to address the causes of the disease. If this proves ineffective or unlikely, resin infiltration has been developed to slow or arrest progression of white-spot lesions. In resin infiltration, the porous lesion body is penetrated by a special low-viscosity resin, blocking the diffusion of cariogenic acids into the lesion. This case report describes the use of a resin infiltrant to treat white-spot lesions in a 24-month-old boy with early childhood caries.

Influence of Staining Solution and Bleaching on Color Stability of Resin Used for Caries Infiltration

OBJECTIVE

The objective of this study was to evaluate the color stability of Icon-infiltrated white spot lesions after staining and the bleaching effect on the infiltrated and stained surfaces.

METHODS AND MATERIALS

Enamel-dentin specimens (N=30, 5 × 5 × 3 mm, 1-mm enamel + 2-mm dentin thickness) were prepared from bovine incisors and randomly allocated into three groups (n=10): control, demineralized, and infiltrated. Artificial enamel subsurface lesions were created using 50 mL of 0.05 M acetate buffer solution. Specimens were produced by Icon application in enamel caries-like lesions, according to the manufacturer's instruction. Baseline color readings were assessed using a spectrophotometer, and CIE L*a*b* measurements of each specimen were performed using a white background. To simulate extrinsic dietary staining, specimens were placed into a 4-mL coffee infusion, three times daily for 15 minutes, for 14 days. After the staining procedure, color measurements were performed again. Then, bleaching procedures were performed using 16% carbamide peroxide gel for four hours daily for 21 days, and a final color assessment was performed. To compare the baseline and final measurements, t-test was used (α =0.05). The statistical comparison between the groups was performed using the one-way analysis of variance and Tukey tests (α =0.05).

RESULTS

Coffee staining provided a significant reduction of L* values and an increase of a* and b* in all groups (control, decayed, and infiltrated). The bleaching procedure provided a significant increase in L* and decrease of a* and b* values in all groups. There was no significant difference in ΔE values between decayed and infiltrated groups before bleaching, and after bleaching, the infiltrated group showed the lowest ΔE values.

CONCLUSION

It can be concluded that enamel infiltrated with Icon presents significant alteration of color after staining when compared with sound enamel. However, if there is discoloration of the infiltrant, the bleaching treatment can be used successfully.

Patterns of failure in colorectal patients with liver metastases after yttrium-90 radioembolization

OBJECTIVES

To assess patterns of failure and factors affecting recurrence patterns in colorectal cancer patients treated with Y-labeled resin microspheres for metastatic liver disease.

METHODS

We retrospectively reviewed 30 colorectal patients treated with Yttrium-90 radioembolization and assessed follow-up computed tomography scans and positron emission tomography scans to determine disease outcomes. All patients were included in survival analysis. Twenty-six patients with hepatic metastases were assessed for patterns of failure after radioembolization treatment and grouped into 3 patterns: (1) hepatic; (2) extrahepatic; and (3) intrahepatic and extrahepatic.

RESULTS

The median overall survival and progression-free survival for all colorectal patients treated with radioembolization was 9.4 and 3.2 months, respectively. Overall survival and progression-free survival were not significantly different between patterns of failure (P=0.43 and 0.26, respectively). Logistic regression analysis demonstrated a trend toward the predictive value of tumor volume in determining patterns of failure. Smaller tumor volumes had a higher predictive probability for extrahepatic failure than larger tumor volumes (P=0.057). Tumor volumes <300 mL were predictive for extrahepatic failure patterns compared with hepatic recurrence (P=0.046).

CONCLUSIONS

Radioembolization with Y-labeled resin microspheres continues to be an effective salvage treatment for colorectal liver metastases. Analysis of patterns of radiologic failure demonstrated that patients treated by radioembolization develop a greater proportion of extrahepatic failure. Tumor volumes >300 mL were predictive for hepatic recurrence, suggesting that increased dosing or retreatment of these lesions may lead to improved hepatic control of disease and better patient outcomes.

Experimental initial partial polymerization method for Fuji II placement evaluated for microleakage with/without Fuji Coat

PURPOSE

This laboratory study evaluated an experimental 1-second initial partial polymerization (IPP) technique using Fuji II LC vs the manufacturer's standard placement (control), both with and without Fuji Coat, relative to microleakage.

METHODS

Class V restorative preparations were placed on the buccal and lingual aspects of 30 permanent, caries-free and restoration-free, third molar teeth. Fuji II LC restorations were placed either following manufacturer-specified guidelines or IPP for 1 second prior to contouring and full light curing. Half of the restorations were placed using the IPP experimental technique and half of the teeth were finished using Fuji Coat LC. Following thermocycling, specimens were sectioned and dye penetration was measured. SPSS 16 was used for statistical analysis (p<0.05).

RESULTS

Mean microleakage results: experimental/varnish (0.08 ± 0.15 mm), control/varnish (0.17 ± 0.35 mm), experimental/nonvarnish (0.33 ± 0.33 mm), and control/nonvarnish (0.58 ± 0.47 mm). Univariate analysis of variance demonstrated significantly less microleakage for the experimental technique (p<0.001), use of finishing varnish (p<0.001), and the combination of experimental/varnish (p=0.013).

CONCLUSIONS

The initial partial polymerization technique of Fuji II LC placement significantly reduces microleakage. Fuji Coat LC results in further diminished microleakage.

Antioxidant responses and renal crystal formation in rainbow trout treated with melamine administered individually or in combination with cyanuric acid

In 2007 and 2008, renal stone formation and kidney damage in human infants were linked to consumption of melamine (MEL)-contaminated infant formula, as well as renal failure and death in pets due to pet food containing both MEL and cyanuric acid (CYA). The aim of this study was to examine the effects of MEL and CYA administered individually or in combination on concentrations of certain metabolites and enzyme activities that serve as markers for oxidative stress in kidney and liver of rainbow trout. In addition, the levels of muscle MEL and renal crystal formation were determined. Trout were fed MEL and/or CYA for 8 wk at 250, 500, or 1000 mg of each compound/kg in feed. Fish muscle residues of MEL exhibited a dose-response relationship. Coexposure of trout to MEL and CYA at the highest dose led to lower MEL residue concentrations in muscle compared to exposure to MEL alone. Renal MEL-CYA complexes were found in kidneys of fish treated with combined MEL and CYA. A dose response was evident with respect to both (1) number of trout displaying renal crystals and (2) number of crystals per fish. Changes in concentration of antioxidant parameters, such as glutathione, superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase, were recorded in both tissues of MEL- and CYA-dosed trout. Lipid peroxidation was more pronounced in kidney than liver. Therefore, feed contaminated with both MEL and CYA could be problematic for fish, as MEL administered to trout, individually or in combination with CYA, may facilitate the onset of oxidative damage in trout.

Differential resin-dentin bonds created after caries removal with polymer burs

The objective of this article was to investigate the effect of carbide and polymer burs caries removal methods on the bond strength of different adhesives to dentin. Resin restorations were performed in sound and caries-affected dentin, after using polymer or carbide burs and bonding with four different adhesive (Single bond, SB; Clearfil SE bond, SEB; FL-Bond II, FLB; and Fuji II-LC, FUJI). Microtensile bond strength (MTBS) was measured. Data were analyzed with ANOVA and Student-Newman-Keuls tests. Debonded surfaces were observed by scanning electron microscopy. Bonded interfaces were examined using light microscopy (Masson's trichrome staining). In sound dentin, MTBS was similar for SEB and SB, and higher than that of FLB and FUJI. Bond strength to carbide bur prepared dentin was similar for SB, SEB, and FLB; FUJI presented the lowest. SB applied on polymer bur excavated dentin presented similar values to those of the carbide bur group; MTBS attained by SEB, FLB, and FUJI decreased when bonding to dentin treated with polymer burs; FUJI yielded pretesting failures in all specimens. Polymer burs created a thick smear layer that was not infiltrated by tested self-etching agents. The bonding effectiveness of self-etching and glass-ionomer-like adhesives to dentin decreased when polymer burs were used.

Efficacy and safety of coadministration of rosuvastatin, ezetimibe, and colestimide in heterozygous familial hypercholesterolemia

Aggressive low-density lipoprotein (LDL) cholesterol-lowering therapy is important for high-risk patients. However, sparse data exist on the impact of combined aggressive LDL cholesterol-lowering therapy in familial hypercholesterolemia (FH), particularly on side effects to changes in plasma coenzyme Q10 and proprotein convertase subtilisin/kexin type 9 levels. We enrolled 17 Japanese patients with heterozygous FH (12 men, 63.9 ± 7.4 years old) with single LDL receptor gene mutations in a prospective open randomized study. Permitted maximum doses of rosuvastatin (20 mg/day), ezetimibe (10 mg/day), and granulated colestimide (3.62 g/day) were introduced sequentially. Serum levels of LDL cholesterol decreased significantly by -66.4% (p <0.001) and 44% of participants achieved LDL cholesterol levels <100 mg/dl. There were no serious side effects or abnormal laboratory data that would have required the protocol to have been terminated except for 1 patient with myalgia. Coadministration of ezetimibe and granulated colestimide further lowered serum LDL cholesterol more than rosuvastatin alone without changing plasma coenzyme Q10 and proprotein convertase subtilisin/kexin type 9 levels. In conclusion, adequate introduction of this aggressive cholesterol-lowering regimen can improve the lipid profile of FH.

Vertebroplasty for vertebral compression fractures secondary to Cushing's syndrome induced by an ACTH-producing bronchial carcinoid tumour

Adrenocorticotropic hormone (ACTH)-producing bronchial carcinoid tumours are a rare cause of Cushing's syndrome. Cushing's syndrome is frequently complicated by osteoporosis, which results in an increased tendency for the development of vertebral compression fractures. Percutaneous vertebroplasty has been shown to be an effective treatment option in the setting of painful osteoporotic compression fractures refractory to conservative therapies. We report a case where vertebroplasty was performed on a 36-year-old woman with osteoporosis and compression fractures secondary to hypercorticolism. A bronchial carcinoid tumour was found to be the source of excess ACTH production. Three-level percutaneous vertebroplasty resulted in a marked improvement in pain.

Single-layer transdermal film containing lidocaine: Modulation of drug release

We have recently described an innovative drug delivery system, a water-based and vapor permeable film intended for dermal and/or transdermal delivery. The aim of this work was to modulate the delivery of the model drug lidocaine hydrochloride from the transdermal film across rabbit ear skin. The effect of drug loading, of film-forming polymer type and content, of adhesive and plasticizer on lidocaine transport across the skin was evaluated. Additional objective was to evaluate the effect of occlusion on the kinetics of lidocaine transport, by applying an occlusive backing on the surface of the transdermal film. From the data obtained it can be concluded that the transdermal film acts as a matrix controlling drug delivery. The film-forming polymer molecular weight had a negligible effect on drug penetration, while its content was more effective. The choice of the adhesive seems to be the most important variable governing drug transport. In particular, the presence of lauric acid combined with a basic drug, such as lidocaine, can produce a relevant improvement in permeation, because of the formation of an ion pair. Concerning the kinetics, drug depletion is responsible for the declining permeation rates observed in the late times of permeation.

Drug release properties of polymer coated ion-exchange resin complexes: experimental and theoretical evaluation

Although ion-exchange resins have been used widely as drug delivery systems, their exact release kinetics has not been reported yet. Usually only the rate-limiting step has been taken into account and the rest of the steps have been ignored as instantaneous processes. To investigate the exact release kinetics of polymer-coated drug/ion-exchange resin complexes for sustained drug delivery, the results of new mathematical modeling were compared with experimental results. Drug/resin complexes with a model drug, dextromethorphan, were prepared and used as cores for fluid-bed coating. An aqueous colloidal dispersion of poly(vinyl acetate) was applied for the coating. A comprehensive mathematical model was developed using a mechanistic approach by considering diffusion, swelling, and ion-exchange processes solved by numerical techniques. The rate-limiting factor of the uncoated resin particles was diffusion through the core matrix. Similarly, in the coated particles the rate-limiting factor was diffusion through the coating membrane. The mathematical model has captured the phenomena observed during experimental evaluations and the release dynamics from uncoated and coated (at different coat levels) particles were predicted accurately (maximum RMSE 2.4%). The mathematical model is a useful tool to theoretically evaluate the drug release properties from coated ion-exchange complexes thus can be used for design purposes.

Polymorphonuclear Leukocytes May Impair Endothelial Function

Objectives— To examine whether polymorphonuclear leukocytes (PMNs) in hypercholesterolemia (HC) are activated to generate large amount of superoxide in vivo and hence impair endothelial function and, if so, whether statins, which possess anti-inflammatory properties, may restore PMN-mediated endothelial dysfunction.

Methods and Results— At baseline, subjects with HC showed impaired endothelial function ( P <0.001), estimated by flow-mediated vasodilation of the brachial artery, and increased susceptibility of low-density lipoprotein (LDL) to oxidation ( P <0.0001) compared with control subjects. PMNs obtained from HC produced greater amount of superoxide ( P <0.0001), showed higher adhesiveness to cultured endothelial cells (HUVECs) ( P <0.0001), and impaired endothelial nitric oxide synthase (eNOS) Ser 1177 phosphorylation of HUVECs compared with controls ( P <0.001). Crossover administration of fluvastatin or colestimide for 3 months lowered LDL to the same levels ( P <0.001 for both). Endothelial function was restored ( P <0.0001). LDL oxidation ( P <0.0001) and superoxide release from PMNs ( P <0.0001) were diminished only in fluvastatin but not in colestimide arm. Fluvastatin attenuated PMN adhesion to HUVECs ( P <0.0001) and restored eNOS Ser 1177 phosphorylation of HUVECs ( P <0.001).

Conclusion— Statins may improve endothelial function at least in part by inactivating neutrophils independently of LDL reduction. Our results raise a novel concept that polymorphonuclear leukocytes may attack endothelia and play a pivotal role in the pathogenesis of atherosclerosis.

Effect of Oral Colestimide on the Elimination of High-dose Methotrexate in Patients With Primary Central Nervous System Lymphoma-Two Case Reports-

Delayed methotrexate (MTX) elimination occurred in two patients with primary central nervous system lymphoma undergoing high-dose MTX treatment. Oral administration of the anion exchange resin colestimide, which binds MTX effectively in vitro, effectively accelerated MTX elimination. Colestimide probably interrupts the enterohepatic circulation, and is a potential oral antidote to MTX toxicity.

Lateral circumflex femoral arterial system and perforators of the anterolateral thigh flap: an anatomic study

The authors performed an anatomic study on 16 thighs of 11 fresh white cadavers at the Ludwig-Maximilian University of Munchen, Germany. They analyzed the anatomic pattern and caliber of both the lateral circumflex femoral arterial system and the perforators nourishing the anterolateral thigh flap. They found regularly a majority of musculocutaneous perforators, mainly in the central third of the thigh, arising from the descending branch of the lateral circumflex femoral artery. Despite the small number of cadavers, they identified several differences in the anatomy of the lateral circumflex femoral arterial system. These variabilities, especially regarding the descending branch and its perforators, could have clinical importance. They also suggest new dissection studies by comparing white and oriental anatomy. Their aim is to establish whether any difference in the variability of the lateral circumflex femoral arterial system could increase the popularity, currently greater in Eastern Europe, of the anterolateral thigh flap.

Sensitizing capacity of some trimers in p-tert-butylphenol-formaldehyde resin

Contact allergy to p-tert-butylphenol formaldehyde resin (PTBP-F-R) is not rare. This resin consists of a large number of substances, most of which are still unknown. For diagnostic and preventive reasons the chemical identity of the sensitizers should be known, as well as their sensitizing capacities, cross-reaction patterns and presence in the environment. The aims of this study were to investigate the sensitizing capacities and potential cross-reacting patterns for 4-tert-butyl- 2,6-bis-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-phenol (XIII), 4-tert-butyl-2- (5 - tert - butyl - 2 - hydroxy-benzyloxymethyl) - 6 - (5 - tert - butyl - 2 - hydroxy - 3 - hydroxymethyl-benzyloxy methyl)-phenol (XIVa) and 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix(3)arene (XVIII) by the guinea pig maximization test. 4-tert-Butyl-2,6-bis-hydroxymethyl-phenol, 4-tert-butylbenzene-1,2-diol, 4-tert-butyl-2-hydroxymethyl-phenol, 4-tert-butyl-phenol, 4-tert-butyl-2-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-6-hydroxymethyl-phenol, 4-tert-butyl-2-[5-tert-butyl-3-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl) - 2 -hydroxy-benzyloxymethyl] - 6 - (5 - tert-butyl- 2 -hydroxy- 3 -hydroxymethyl-benzyloxymethyl)- phenol and were used as potential cross-reacting substances. In this study it is strongly indicated that the linear trimer XIII has a sensitizing capacity in the guinea pig which was significant when compared to the controls (p = 0.024). No cross-reactions were detected in animals induced with the linear trimer XIII. The linear trimer XIVa and the cyclic trimer XVIII failed to induce sensitization.

Development of a novel nasal nicotine formulation comprising an optimal pulsatile and sustained plasma nicotine profile for smoking cessation

A novel nasal formulation, in the form of a nicotine-Amberlite resin complex powder has been developed that provided an optimal combined pulsatile and sustained plasma nicotine profile for smoking cessation. The adsorption isotherms of nicotine hydrogen tartrate salt on two types of Amberlite resins (IRP69 and IR120) were evaluated and the subsequent in vitro release properties of nicotine from the nicotine-Amberlite complex powders were tested using a Franz diffusion cell. Amberlite IRP69 and Amberlite IR120 are similar cationic exchange materials with the same ion-exchange capacity but due to a smaller particle size range (10-150 microm) Amberlite IRP69 had a better flow property and a better adsorptive capacity than Amberlite IR120. The material is used as an excipient in marketed pharmaceutical formulations. The highly water soluble salt, nicotine hydrogen tartrate, displayed good adsorption onto both types of Amberlite resin. The maximum adsorption of nicotine onto Amberlite IRP69 was 1.071 mg drug per mg resin. The cumulative release of drug from nicotine hydrogen tartrate-Amberlite complex powders showed that the higher the drug loading, the faster was the rate of release of the drug. Based on these results, various nicotine hydrogen tartrate-Amberlite IRP69 powder formulations containing different ratios of free to bound drug (50% to 100% bound) and a control solution were prepared and evaluated in a sheep model by nasal administration. The nicotine plasma profiles demonstrated that an initial rapid peak plasma level of nicotine followed by a sustained elevated level could be achieved by adjusting the ratio of free to bound nicotine in the Amberlite powder formulation. The curves obtained from some of the formulations were comparable to those predicted from a computer-generated pharmacokinetic model.

The histological effects of four endodontic sealers implanted in the oral mucosa: submucous injection versus implant in polyethylene tubes

AIM

The aim of this study was to evaluate pigmentation and tissue response to four endodontic sealers placed in the oral mucosa of rabbits by either submucous injection or implant in polyethylene tubes.

METHODOLOGY

Thirty white New Zealand rabbits were divided randomly into two groups of eight for N-Rickert and AH-26, and two groups of seven for Fillcanal and Sealer 2 6. On the right side of the filter, corresponding to the gingivo-labial sulcus in humans, the sealer was injected; on the left side the sealer was placed within a polyethylene tube and implanted. Direct clinical observations were made at 30, 60 and 90 days. The animals were then sacrificed for histological analysis.

RESULTS

After 60 days of observation N-Rickert and AH-26 produced tattoos that became larger by 90 days. Submucous injection produced larger and more numerous pigmentation, when compared to implant in polyethylene tubes. N-Rickert sealer displayed larger and more numerous tattoos when compared to AH-26. Histological analysis showed no differences between the two methods of implantation. All sealers elicited some kind of inflammatory response; the most irritant was Fillcanal, followed by N-Rickert and AH-26. Sealer 26 elicited a mild reaction only.

CONCLUSIONS

Under the conditions of this study there was no relationship between the method of implantation and the tissue response; the silver-containing sealers produced pigmentation, and the concentration of silver influenced the quantity and size of the tattoos. The sealers elicited various responses when in direct contact with the surrounding tissues: the calcium hydroxide-containing sealer had enhanced healing when compared to the other sealers.

Acute abdomen with colonic necrosis induced by Kayexalate-sorbitol

Colonic necrosis is an unusual complication after treatment of hyperkalemia with sodium polystyrene sulfonate (SPS, Kayexalate) in sorbitol. To increase awareness of this complication, we report a case of necrosis of the transverse colon in a patient given oral and rectal SPS-sorbitol for hyperkalemia. Colonic necrosis was manifested as an acute abdomen within 24 hours of initial administration. Prompt surgical resection of the necrotic transverse colon permitted rapid recovery of bowel function. Although SPS crystals are seen microscopically in the necrotic bowel, experimental evidence implicates the sorbitol component of the SPS-sorbitol in the pathogenesis of colonic necrosis. A high index of suspicion for the unusual complication of colonic necrosis after oral or rectal administration of SPS-sorbitol may allow prompt recognition and surgical cure.

Effect of single dose resin-cathartic therapy on serum potassium concentration in patients with end-stage renal disease

Hyperkalemia in patients with renal failure is frequently treated with a cation exchange resin (sodium polystyrene sulfonate, hereafter referred to as resin) in combination with a cathartic, but the effect of such therapy on serum potassium concentration has not been established. This study evaluates the effect of four single-dose resin-cathartic regimens and placebo on 5 different test days in six patients with chronic renal failure. Dietary intake was controlled. Fecal potassium output and serum potassium concentration were measured for 12 h. Phenolphthalein alone caused an average fecal potassium output of 54 mEq. The addition of resin caused an increase in insoluble potassium output but a decrease in soluble potassium output; therefore, there was no significant effect of resin on total potassium output. Sorbitol plus resin caused less potassium output than phenolphthalein plus resin. On placebo therapy, the average serum potassium concentration increased slightly (0.4 mEq/L) during the 12-h experiment. This rise was apparently abrogated by some of the regimens that included resin; this may have been due in part to extracellular volume expansion caused by absorption of sodium released from resin. Phenolphthalein regimens were associated with a slight rise in serum potassium concentrations (similar to placebo); this may have been due to extracellular volume contraction produced by high volume and sodium-rich diarrhea and acidosis secondary to bicarbonate losses. None of the regimens reduced serum potassium concentrations, compared with baseline levels. Because single-dose resin-cathartic therapy produces no or only trivial reductions in serum potassium concentration, and because this therapy is unpleasant and occasionally is associated with serious complications, this study questions the wisdom of its use in the management of acute hyperkalemic episodes.

Injection technique and scanning electron microscopic study of the arterial pattern of the 20 gestation days (G20) rat fetus

A technique to obtain microvascular corrosion casts of the G20 rat fetus and the normal pattern of the main arteries of the G20 rat fetus are described. The casts were studied by means of scanning electron microscopy (SEM). The arterial pattern is similar to that described in the adult; however, several variations have been found. It is concluded that the use of vascular corrosion casts studied by SEM may be particularly helpful to observe the extremely small arteries of rat fetuses. Moreover, we suggest that this technique may be useful in practical teratological studies.

Clinical observations of noncoping overdenture abutments protected by tannin-fluoride preparation

STATEMENT OF PROBLEM

The exposed dentin of overdenture abutments can lead to caries. Therefore chemical protection is needed to prevent caries. Considering that dentin contains both organic and inorganic components, reinforcement of both components should give reasonable results. Tannin-fluoride preparation strengthens both the organic and inorganic components of teeth.

PURPOSE

This study examined whether the tannin-fluoride preparation protects noncoping abutments.

MATERIAL AND METHODS

Thirty-one subjects aged 36 to 86 years participated in the clinical trial. A trial autopolymerizing resin containing the preparation or a conventional autopolymerizing resin was applied to the inner surface of the denture base, which was in contact with the abutments. When there were autopolymerizing resin group abutments, there was also at least one preparation group abutment under the overdenture.

RESULTS

The incidence of caries in the preparation and autopolymerizing resin groups were 0% and 0%, respectively, for the first 2 years, 4.5% and 0%, respectively, during the 3- to 4-year period, 13.8% and 75%, respectively, during the 5- to 8-year period, and 10% and 15%, respectively, in total. Gingival crevicular fluid demonstrated a tendency to decrease in both groups over time.

CONCLUSION

The trial autopolymerizing resin containing the preparation has a long-term caries prevention effect, and helps to maintain gingival health. Without adding clinical steps, abutments can be protected by the tannin-fluoride preparation.

Noninvasive measurement of human ascending colon volume

The capacitance and motor functions of the colon are important determinants of its overall function. A simple, noninvasive method to quantify regional colonic volume is required for further physiologic and pharmacologic studies. Our aim was to determine whether measurements of human ascending colon (AC) volume using two-dimensional (2-D) images are as accurate as estimates using three-dimensional (3-D) images. Five healthy male volunteers each ingested a methacrylate-coated capsule containing 99Tcm-labelled Amberlite pellets. Two-and 3-D images were obtained using a gamma camera with single photon emission computed tomography (SPECT) capability. Ascending colon volume was estimated by a variable region of interest (VROI) program and by full-width half-maximum (FWHM) analysis, and results were compared to the volume estimates by SPECT. Full-width half-maximum analysis yielded volume estimates that were not significantly different from SPECT (slope = 1.093; t = 0.51; P > 0.5), whereas VROI estimates were significantly different from volume measurements by SPECT and, hence, considered less accurate (slope = 0.438; t = 4.93; P < 0.02). Thus, the less expensive and more easily available planar imaging technique with analysis by FWHM estimates AC volume as accurately as SPECT.

[Isolation of nisin from native solution and its purification on cationites]

It was found possible to use organic sorbents and in particular carboxylic cationites for isolation of nisin from the fermentation broth filtrate and its purification. Nisin is known as a polypeptide antibiotic applied as a preservative. The sorbents were shown to have high exchange capacities by the isolated substance and mechanical strength and resistance. They also proved to be highly stable.

[Studies on the teratogenic potential of p-tert-butylphenolformaldehyde resin in rats]

p-tert-Butylphenolformaldehyde resin, an adhesive, was given orally to pregnant Wistar rats by stomach intubation at the dose levels of 250, 500 and 1000 mg/kg body weight during days 7 to 17 of gestation, and the effects of the compound on dams and fetal developments were examined. No changes in general conditions, maternal body weight, food consumption, numbers of corpora lutea and implantation ratio were observed. There was no evidence of an increase in fetal death or of malformation attributable to the treatment with p-tert-butylphenolformaldehyde resin in any of dose levels examined. It was concluded that p-tert-butylphenolformaldehyde resin has no teratogenic effect in rats.

Multiple-dose sodium polystyrene sulfonate in lithium intoxication: an animal model

Previous work in our laboratory has demonstrated that sodium polystyrene sulfonate (SPS) significantly lowered serum lithium (Li) concentrations when administered in a single oral dose after an oral dose of lithium in a mouse model. The present study was designed to determine whether: 1) repetitive doses of SPS are effective in lowering serum lithium concentrations, 2) the effect of SPS on lithium concentration is dose related and 3) SPS enhances the elimination of lithium. Mice (N = 144) were given orogastric LiCl (250 mg/kg) and then divided into 4 groups: Controls received water 0, 30, 90, 180, and 360 min. after LiCl; the Full-Dose SPS Group received SPS (5 g/kg/dose) at equivalent times; the Half-Dose SPS Group received SPS (2.5 g/kg/dose) at the same times; and the Elimination Group received water at 0 and 30 min. after LiCl and SPS at 90, 180 and 360 min. after LiCl. Subgroups of each group were sacrificed at 1, 2, 4 and 8 hr post-treatment and serum analyzed for lithium concentrations. Statistical analyses revealed that, when compared to Controls: 1) SPS significantly lowered serum lithium concentrations; 2) this effect was dose-related; 3) repetitive dosing of SPS appears to enhance the elimination of lithium.

[Arteriovenous anastomosis in nasal cavities using microcorrosion technique]

In the present study the morphology of arteriovenous anastomoses in the nasal area are analyzed using the microcorrosion technique. This technique calls for perfusion of the vascular system, passing through the left ventricle, with Batson's of the vessels. For the first time in the microcorrosion study of the nasal vascular network human fetuses (from the 12th to 24th week of intrauterine life) obtained from spontaneous abortions were used as well as rats weighing from 250 to 300 gr. The animals were anesthetized with sodium thiopental prior to administration of the resin. A specimen containing the facial muscles, the nasal pyramid, the maxillary bone and the palatine bones was excised. Then, from this specimen the nasal septum and the two lateral portions of the nose were obtained. The bony and soft perivascular tissues were removed by placing the casts in an aqueous 20% KOH solution. Finally the corrosion cases were observed under a scanning electron microscope (EM). Within the nasal cavities the microcorrosion technique makes it possible to identify three different vascular layers: superficial, intermediate and deep. In the latter it proved possible to visualize the two types of arteriovenous anastomoses: i.e. simple and complex. On the basis of both vascular course and the impressions left by the endothelial cell nuclei it proved possible to differentiate between the arterial and venous portions of the anastomoses.