Effect of Polymeric Microparticles Loaded With Catechin on the Physicochemical Properties of an Adhesive System.

The objective of this study was to synthesize and characterize epigallocatechin-3-gallate (EGCG)-loaded/poly(D-L lactide-co-glycolide) acid (PLGA) microparticles, evaluate their effects on degree of conversion and release assay of adhesives, and subsequently to examine the resin-dentin bond strength of two EGCG formulations (free EGCG or loaded into PLGA microparticles) applied as a pretreatment or incorporated into an adhesive system. The formulations were prepared according to a PLGA:EGCG ratio of 16:1 using the spray-drying technique. The size and polydispersity index were determined by light scattering in aqueous dispersion. The degree of conversion (%DC) and release assay were assessed by Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer, respectively. Subsequently, 45 third molars were divided into five groups (n=9) according to the different EGCG application modes and prepared for bond strength testing in a universal testing machine. Results demonstrated no statistically significant difference among the DC means after the PLGA microparticles were loaded with EGCG. For the release assay, the 1.0% PLGA/EGCG group presented better results after being elected for use in the bond strength test. The resin-dentin bond strengths of the experimental groups after 12 months of water storage were significantly higher than in the control group. EGCG could improve the durability of the resin-dentin bond over time and promote a new era for adhesive dentistry with the concept of controlled release.

Effectiveness of Different Mechanical Methods on Dentin Caries Removal: Micro-CT and Digital Image Evaluation.

PURPOSE: To determine the caries removal effectiveness (CRE) and minimal invasive potential (MIP) of caries excavation methods using digital imaging and microtomography analyses. METHODS: Twelve human molars with occlusal caries lesions in dentin were randomly divided into three groups (carbide bur, exacavator, and polymer bur). They were sectioned mesiodistally, and standardized digital and computed microtomography x-ray (micro-CT) images were taken from each section before and after caries excavation. On each image, initial carious dentin (IC), prepared cavity (PC), and residual caries (RC) were defined according to visual criteria using ImageJ software. CRE was determined based on the RC/IC ratio, whereas MIP was determined by the PC/IC ratio. Data were analyzed using one-way analysis of variance and Student t-test or with Kruskal-Wallis and Student-Newman-Keuls test. The level of significance was set at 0.05. RESULTS: For both digital image and micro-CT analysis, the carbide bur showed higher CRE values than the excavator (p=0.0063 and p=0.0263, respectively) and the polymer bur (p=0.0028 and p=0.0005, respectively). The latter two presented similar results (p>0.05). Regarding MIP, for the digital image analysis, the polymer bur was different from the carbide bur (p=0.0030) but was not different from that of the excavator (p=0.1240). For micro-CT analysis, the MIP values of all the groups were significantly different, and the polymer bur was the most conservative method (p<0.05). CONCLUSIONS: The carbide bur was the most effective method for caries removal but was not completely conservative. The polymer bur and excavator presented low invasive potential but were not able to remove all of the carious dentin.

Zinc-inhibited MMP-mediated collagen degradation after different dentine demineralization procedures.

BACKGROUND: Dentine matrix metalloproteinases (MMPs) play an important role in the dentine caries process. AIMS: To determine if MMP-mediated collagen degradation of acid-demineralized dentine may be inhibited by zinc or zinc chelators. METHODS: Human dentine specimens were demineralized by phosphoric acid (PA), ethylenediaminetetraacetic acid (EDTA), Clearfil SE Bond primer (SE), or Xeno V (XE) and stored in artificial saliva. Chlorhexidine digluconate (CHX), doxycycline, EDTA, or ZnCl(2) was added. C-terminal telopeptide determinations (ICTP) were performed by radioimmunoassay after 24 h and 4 weeks. RESULTS: Collagen degradation was prominent in PA-demineralized (ICTP values from 74.01 µg/l at 24 h to 202.46 µg/l after 4 weeks) and EDTA-demineralized dentine (ICTP values from 83.93 µg/l at 24 h to 158.82 µg/l after 4 weeks) stored in artificial saliva. Doxycycline fully blocked proteolysis. CHX and EDTA reduced collagen degradation only at 24 h. Zinc in excess strongly inhibited hydrolysis of collagen in all tested groups (ICTP values were: PA, 13.56 µg/l; EDTA, 11.21 µg/l; SE, 1.52 µg/l, and XE, 2.37 µg/l) and its effect was maintained for up to 4 weeks, except for EDTA-treated dentine (ICTP values were: PA, 40.76 µg/l; EDTA, 79.15 µg/l; SE, 5.29 µg/l, and XE, 6.38 µg/l). CONCLUSION: EDTA and CHX exerted time-limited MMP inhibition, and excess zinc served as an effective inhibitor of MMP-mediated collagen degradation in strong or mildly demineralized dentine. MMP degradation of collagen was reduced in resin-infiltrated dentine; the presence of excess zinc chloride exerted an additional protective effect.

Zinc reduces collagen degradation in demineralized human dentin explants.

OBJECTIVES: Dentin matrix metalloproteinases are implicated in the pathogenesis of caries and contribute to collagen degradation in resin-dentin interfaces. The objective was to determine if collagen degradation may be modulated by an excess of zinc or zinc chelators. METHODS: Mineralized and phosphoric acid demineralized human dentin specimens were tested. Chlorhexidine digluconate, doxycycline or ZnCl2 were added to the media. In half of the groups, active exogenous metalloproteinase-2 was incorporated into the solution. C-terminal telopeptide determinations (radioimmunoassay) were performed after 24 h, 1 and 3 weeks. RESULTS: Collagen degradation was prominent in demineralized dentin. Doxycycline fully blocked dentin proteolysis. Chlorhexidine digluconate reduced the degradation at the 24-h period. Zinc in excess strongly inhibits hydrolysis of collagen and its effect was maintained for 3 weeks. CONCLUSIONS: Zinc in excess reduces MMP-mediated collagen degradation. The hypothesis that binding of zinc to collagen results in protection of sensitive cleavage sites of metalloproteinases requires further validation.

Degradation of resin-dentin bonds using NaOCl storage.

OBJECTIVE: Several recent studies have reported collagen hydrolysis within bonds over the long-term. This may be one reason for the degradation of the bonds. This study therefore aimed to determine the effects of NaOCl on adhesive system bonds (total-etch bonding system vs. self-etching primer system) to dentin in order to accelerate the durability testing. METHODS: Resin-dentin bonded specimens were produced using Liner Bond 2V (Kuraray), a self-etching primer system, and OptiBond SOLO (Kerr), a total-etch bonding system, according to the manufacturers' instructions. The bonded specimens were serially sectioned in both x and y directions across the adhesive interface to obtain beams (adhesive area: 0.9 mm(2)). The specimens were immersed in 10% NaOCl solution for 1-5h after being stored in water at 37 degrees C for 24h. Control specimens were tested without exposure to NaOCl. After storage, micro-tensile bond tests were performed. Results were analyzed by two-way ANOVA and Fisher's PLSD tests (p<0.05). All fractured surfaces were observed by SEM, and examined using an image analyzer. RESULTS: The bond strengths decreased with increasing storage time in NaOCl. Fractography showed that NaOCl had a greater effect on the bond structure of OptiBond SOLO than on that of Liner Bond 2V, although both adhesives were susceptible. SIGNIFICANCE: Deterioration of the bonds was responsible for the effect of NaOCl on the hybrid layer. This deterioration may occur in humans in cases of deproteinization within the bonds.

[Successful non-surgical treatment of acute coronary syndrome involving the left main coronary trunk in four elderly patients].

We encountered 4 patients aged over 80 with acute coronary syndrome involving the left main coronary trunk (LMT) who obtained a successful outcome by non-surgical management. CASE 1: An 80-year-old women suffered acute myocardial infarction. A coronary stent was placed at the orifice of the LMT for dilatation of severe 90% stenosis. Cardiac function was markedly improved after treatment during the chronic period. CASE 2: An 81-year-old man who developed non-sustained ventricular tachycardia. Coronary angiography demonstrated severe stenosis with haziness of the LMT. Intra-aortic balloon pumping was performed for one whole day after the attack and the follow-up study performed one month later revealed that the stenosis was markedly diminished to an insignificant grade without residual ischemia. CASE 3: An 81-year-old man developed acute inferior wall infarction with a background of severe triple vessel disease accompanied by an LMT lesion. Coronary stents were placed at three sites, i.e., the right coronary, LMT, and left anterior descending branch. Though initial treatment was successful, this patient died due to severe arrhythmia. Patients in who CABG is strongly indicated due to LMT lesion complicated with multiple organ disorders will increase as the population of the aged continues to increase in Japan. We obtained satisfactory results by intensive intense non-surgical management including PTCA. From our experience, adequate selection of therapeutic regimens for individual patients is important to improve the long-term prognosis as well as the immediate outcome in the acute stage.

[A case of adrenal metastasis of lung cancer treated by carboplatin and docetaxel].

A 42-year-old male was referred to our hospital in October 1998, suffering from severe cough accompanied by repeated hemosputa. Serum NSE slightly increased and cytology of sputum indicated class V. Chest X-P and CT revealed a large tumor in the right upper lobe and hilar lymphadenopathy. Abdominal CT revealed bilateral adrenal tumors. For continuous bloody sputum, a right upper lobectomy and lymphadenectomy were performed and the pathologic diagnosis was large cell carcinoma. After surgery, we chose radiation and chemotherapy. The new chemotherapeutic agent docetaxel (60 mg/m2 in combination with carboplatin (CBDCA: AUC 6,800 mg/m2) was administered, resulting in the remarkable reduction in the size of adrenal metastasis by 50% after 3 courses of chemotherapy. Furthermore, 12 months later, the right adrenal metastasis was remarkably reduced (5 x 3 cm-> 0.5 x 1.0 cm), and the left adrenal metastasis had disappeared on abdominal CT. These findings may suggest the efficacy of newly developed docetaxel in cases of non-small cell lung cancer.