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Lesion Depth (lesion + depth)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Ex vivo histological characterization of a novel ablative fractional resurfacing device,

LASERS IN SURGERY AND MEDICINE, Issue 2 2007
Basil M. Hantash MD
Abstract Background and Objectives We introduce a novel CO2 laser device that utilizes ablative fractional resurfacing for deep dermal tissue removal and characterize the resultant thermal effects in skin. Study Design/Materials and Methods A prototype 30 W, 10.6 µm CO2 laser was focused to a 1/e2 spot size of 120 µm and pulse duration up to 0.7 milliseconds to achieve a microarray pattern in ex vivo human skin. Lesion depth and width were assessed histologically using either hematoxylin & eosin (H&E) or lactate dehyrdogenase (LDH) stain. Pulse energies were varied to determine their effect on lesion dimensions. Results Microarrays of ablative and thermal injury were created in fresh ex vivo human skin irradiated with the prototype CO2 laser device. Zones of tissue ablation were surrounded by areas of tissue coagulation spanning the epidermis and part of the dermis. A thin condensed lining on the interior wall of the lesion cavity was observed consistent with eschar formation. At 23.3 mJ, the lesion width was approximately 350 µm and depth 1 mm. In this configuration, the cavities were spaced approximately 500 µm apart and interlesional epidermis and dermis demonstrated viable tissue by LDH staining. Conclusion A novel prototype ablative CO2 laser device operating in a fractional mode was developed and its resultant thermal effects in human abdominal tissue were characterized. We discovered that controlled microarray patterns could be deposited in skin with variable depths of dermal tissue ablation depending on the treatment pulse energy. This is the first report to characterize the successful use of ablative fractional resurfacing as a potential approach to dermatological treatment. Lasers Surg. Med. 39:87,95, 2007. © 2007 Wiley-Liss, Inc. [source]

Bacterial composition and red fluorescence of plaque in relation to primary and secondary caries next to composite: an in situ study

MOLECULAR ORAL MICROBIOLOGY, Issue 1 2008
R. Z. Thomas
Background/hypothesis:, Secondary caries has been suggested as the main reason for restoration replacement. We hypothesized that more caries-associated bacteria are found on composite resin restoration material, compared to sound tooth tissue. Methods:, Both restored and unrestored dentin and enamel samples were placed in a full denture of eight subjects for 20 weeks. The microbiological composition of approximal plaque and the association between caries-associated bacteria and red autofluorescence of dental plaque was studied. Every 4 weeks the specimens were microradiographed using transversal wavelength independent microradiography (T-WIM). After 1 and 20 weeks red fluorescence pictures and plaque samples were taken. Samples were cultured for total anaerobic counts, mutans streptococci, lactobacilli, candida and Actinomyces odontolyticus. Results:, Lesion depth in the dentin and enamel was positively associated with lactobacilli, and lesion depth in dentin was positively associated with A. odontolyticus, whereas no association was found between mutans streptococci and lesion depth. The red-fluorescent bacteria A. odontolyticus and lactobacilli did not correlate with red-fluorescent plaque, indicating that red fluorescence is probably not caused by a single species of these bacteria. After 20 weeks, a higher proportion of combined mutans streptococci and lactobacilli was found on restored tissue compared to non-restored tissue (P = 0.04). Conclusion:, The higher proportion of caries-associated bacteria on restored tissue indicates that the ecology on the surface of primary lesions differs from that on lesions next to composite, and that secondary caries next to composite may differ from the primary caries process. [source]

Linear Radiofrequency Microcatheter Ablation Guided by Phased Array Intracardiac Echocardiography Combined with Temperature Decay

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2009
DAVID KEANE M.D., Ph.D.
Background:Fluoroscopy-guided catheter placement is limited in its ability to determine electrode-endocardial contact and involves radiation exposure. We hypothesized that (1) intracardiac echocardiography (ICE) would provide superior assessment of linear electrode contact compared to fluoroscopy and (2) slow temperature decay upon discontinuation of the radiofrequency current (time for temperature to fall 90% after a 10-second test application of the radiofrequency current T90) would indicate optimal electrode-myocardial contact. Methods:Sixty endocardial lesions were created in the atria and ventricles of six goats by simultaneous delivery of the radiofrequency current through two linear electrodes of a microcatheter with a central interelectrode thermocouple. Catheter placement was guided by fluoroscopy. A 7.5-MHz ICE transducer in the right atrium or ventricle assessed electrode contact. T90 and previously reported parameters of electrode contact and lesion formation were recorded. Histomorphometry was performed on the lesions. Results:T90 was 4.27 ± 4.98 seconds. Lesion depth significantly correlated with ICE assessment of electrode contact (r = 0.56, P = 0.001); T90 upon radiofrequency current offset (r = 0.48, P = 0.008), impedance fall upon radiofrequency current onset (r = 0.37, P = 0.008), bipolar pacing threshold preablation (r =,0.56, P = 0.001), bipolar electrogram amplitude preablation (r = 0.43, P = 0.02), but not with fluoroscopic assessment of the electrode contact (r = 0.18, n.s.). For the prediction of achieving a lesion depth of >2 mm, a T90 of >4.0 seconds yielded a specificity of 86% and a sensitivity of 52%, ICE yielded a specificity and sensitivity of 58% and 68%, respectively, while the specificity and sensitivity of fluoroscopy were 26% and 68%, respectively. Both ICE and T90 provide additional clinical relevance during guidance of cardiac microcatheter ablation. [source]

Gold-Tip Electrodes,A New "Deep Lesion" Technology for Catheter Ablation?

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2005
In Vitro Comparison of a Gold Alloy Versus Platinum, Iridium Tip Electrode Ablation Catheter
Radiofrequency (RF) catheter ablation is widely used to induce focal myocardial necrosis using the effect of resistive heating through high-frequency current delivery. It is current standard to limit the target tissue,electrode interface temperature to a maximum of 60,70°C to avoid char formation. Gold (Au) exhibits a thermal conductivity of nearly four times greater than platinum (Pt,Ir) (3.17 W/cm Kelvin vs 0.716 W/cm Kelvin), it was therefore hypothesized that RF ablation using a gold electrode would create broader and deeper lesions as a result of a better heat conduction from the tissue,electrode interface and additional cooling of the gold electrode by "heat loss" to the intracardiac blood. Both mechanisms would allow applying more RF power to the tissue before the electrode,tissue interface temperature limit is reached. To test this hypothesis, we performed in vitro isolated liver and pig heart investigations comparing lesion depths of a new Au-alloy-tip electrode to standard Pt,Ir electrode material. Mean lesion depth in liver tissue for Pt,Ir was 4.33 ± 0.45 mm (n = 60) whereas Au electrode was able to achieve significantly deeper lesions (5.86 ± 0.37 mm [n = 60; P < 0.001]). The mean power delivered using Pt,Ir was 6.95 ± 2.41 W whereas Au tip electrode delivered 9.64 ± 3.78 W indicating a statistically significant difference (P < 0.05). In vitro pig heart tissue Au ablation (n = 20) increased significantly the lesion depth (Au: 4.85 ± 1.01 mm, Pt,Ir: 2.96 ± 0.81 mm, n = 20; P < 0.001). Au tip electrode again applied significantly more power (P < 0.001). Gold-tip electrode catheters were able to induce deeper lesions using RF ablation in vitro as compared to Pt,Ir tip electrode material. In liver and in pig heart tissue, the increase in lesion depth was associated with a significant increase in the average power applied with the gold electrode at the same level of electrode,tissue temperature as compared to platinum material. [source]

Effects of Temporal Application Parameters on Lesion Dimensions During Transvenous Catheter Cryoablation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2005
HUNG-FAT TSE M.D.
Background: Transvenous catheter cryoablation is a novel technique for treating cardiac arrhythmias. However, the relative importance of temporal application parameters on lesion dimension and clinical efficacy has not been studied. Methods and Results: We investigated the effects of (1) application duration: single 2.5 (2.5 × 1) versus single 5 versus double 2.5 (2.5 × 2) versus double 5 (5 × 2) minutes, (2) number of freeze,thaw cycles: single versus double, and (3) electrode contact area: horizontal versus vertical orientation, on the lesion diameter and depth during catheter cryoablation (10F, 6.5-mm tip-electrode, CryoCorÔ, San Diego) in a thigh muscle preparation. A total of 175 lesions (horizontal = 90, vertical = 85) were created in thigh muscle preparations on 10 swine. The lesion diameter and depth were significantly greater using 2.5 × 2 and 5 × 2 application modes as compared with 2.5 × 1 applications (P < 0.05). Horizontal tip-electrode orientation produced larger lesion diameter (P < 0.05), but not lesion depth as compared with vertical orientation. Multivariate analysis demonstrated that both tip-electrode orientation and duration of freeze >2.5 minutes were independent predictors for lesion diameter (P < 0.001). However, only duration of freeze >2.5 minutes was an independent predictor for lesion depth (P < 0.001). Conclusions: The dimensions of lesions created by catheter cryoablation are affected by mode of cryoablation application and electrode orientation. Increasing the duration of application, employing multiple freeze,thaw cycles at shorter cycle durations, and orienting the catheter to enhance/increase tissue contact can create a larger lesion. [source]

Microradiographic study on the effects of salivary proteins on in vitro demineralization of bovine enamel

JOURNAL OF ORAL REHABILITATION, Issue 2 2005
A. M. KIELBASSA
summary, The aim of this investigation was to evaluate the effects of various proteins on in vitro demineralization of bovine enamel. From each of 100 bovine incisors two samples were prepared. The specimens were embedded in epoxy resin and polished up to 4000 grit. Subsequently, the specimens' surfaces were partly covered with nail varnish, thus serving as control of sound enamel. The specimens were divided randomly into five groups (n = 40) and demineralized in a solution of constant composition (pH 5·0; 10 days). For each subgroup of specimens (n = 10) 4 L were taken and either low (50% of medium conc.), medium, or high (150%) concentrations of the proteins [human albumin (100% conc. = 7 mg L,1), mucin (577·5 mg L,1), immunoglobulin G (IgG) (46 mg L,1), casein isolated from bovine milk (1·2 g L,1)] or amino acid [l -Proline (7 mg L,1)] were added to 1 L of the demineralizing solution, whereas 1 L served as control. Mineral loss and lesion depth (LD) were evaluated from microradiographs of thin sections (110 ,m) by a dedicated software package (TMR 1.24). No differences were found between the five control groups (P > 0·05; anova). Albumin, l -Proline, and IgG did not affect enamel demineralization, whereas the addition of both casein and mucin resulted in significant reductions of both mineral loss and LDs (P < 0·01; Tukey's test). Within the limitations of an in vitro study, the present investigation indicates that casein and mucin seem to affect enamel demineralization significantly. Thus, these proteins might be helpful as an additive to saliva substitutes or mouthwashes if the quality of saliva is altered. [source]

Selective transcutaneous delivery of energy to porcine soft tissues using intense ultrasound (IUS),,

LASERS IN SURGERY AND MEDICINE, Issue 2 2008
W. Matthew White MD
Abstract Objective Various energy delivery systems have been utilized to treat superficial rhytids in the aging face. The Intense Ultrasound System (IUS) is a novel modality capable of transcutaneously delivering controlled thermal energy at various depths while sparing the overlying tissues. The purpose of this feasibility study was to evaluate the response of porcine tissues to various IUS energy source conditions. Further evaluation was performed of the built-in imaging capabilities of the device. Materials and Methods Simulations were performed on ex vivo porcine tissues to estimate the thermal dose distribution in tissues after IUS exposures to determine the unique source settings that would produce thermal injury zones (TIZs) at given depths. Exposures were performed at escalating power settings and different exposure times (in the range of 1,7.6 J) using three IUS handpieces with unique frequencies and focal depths. Ultrasound imaging was performed before and after IUS exposures to detect changes in tissue consistency. Porcine tissues were examined using nitro-blue tetrazolium chloride (NBTC) staining sensitive for thermal lesions, both grossly and histologically. The dimensions and depth of the TIZs were measured from digital photographs and compared. Results IUS can reliably achieve discrete, TIZ at various depths within tissue without surface disruption. Changes in the TIZ dimensions and shape were observed as source settings were varied. As the source energy was increased, the thermal lesions became larger by growing proximally towards the tissue surface. Maximum lesion depth closely approximated the pre-set focal depth of a given handpiece. Ultrasound imaging detected well-demarcated TIZ at depths within the porcine muscle tissue. Conclusion This study demonstrates the response of porcine tissue to various energy dose levels of Intense Ultrasound. Further study, especially on human facial tissue, is necessary in order to understand the utility of this modality in treating the aging face and potentially, other cosmetic applications. Lesers Surg. Med. 40:67,75, 2008. © 2008 Wiley-Liss, Inc. [source]

Anticaries effect of compounds extracted from Galla Chinensis in a multispecies biofilm model

MOLECULAR ORAL MICROBIOLOGY, Issue 6 2008
Q. Xie
Introduction:,Galla Chinensis is a leaf gall known to have some antibacterial effects. Using an in vitro biofilm model of dental plaque, the present study aimed to evaluate the anticaries effects of Galla Chinensis and its chemical fractions. Methods:, A four-organism bacterial consortium (Streptococcus sanguis, Streptococcus mutans, Actinomyces naeslundii, Lactobacillus rhamnosus) was grown on hydroxyapatite (HA) discs, bovine enamel blocks, and glass surfaces in a continuous culture system and exposed to repeated solution pulses. Galla Chinensis extracts, sucrose solutions, and sodium fluoride solutions were pulsed into different flow cells. The pH value of the planktonic phase in each flow cell was recorded and the bacteria colonizing the biofilm on the HA discs were counted. Enamel blocks were observed using a polarized microscope and lesion depth was evaluated. The biofilm morphology was examined with a fluorescence microscope and the images captured were analyzed on an image analysis system. Results:, When Galla Chinensis extract, its chemical fraction, or fluoride was added to the sucrose solution, the planktonic phase pH remained higher than that in the sucrose alone. A lower level of colonization on the HA surface was also observed in the groups to which Galla Chinensis and fluoride were added compared with the control sucrose group, and this was reflected in both the total viable count and the biofilm imaging, which showed fewer cariogenic bacteria and a less compact biofilm, respectively. Enamel demineralization in both the fluoride group and the Galla Chinensis group was significantly less than that in the sucrose group. Conclusions:,Galla Chinensis and fluoride may inhibit the cariogenicity of the oral biofilm. Galla Chinensis appears to be a promising source of new agents that may prevent dental caries. [source]

Bacterial composition and red fluorescence of plaque in relation to primary and secondary caries next to composite: an in situ study

Linear Radiofrequency Microcatheter Ablation Guided by Phased Array Intracardiac Echocardiography Combined with Temperature Decay

The Effect of Ablation Electrode Length and Catheter Tip to Endocardial Orientation on Radiofrequency Lesion Size in the Canine Right Atrium

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2002
RODRIGO C. CHAN
CHAN, R.C., et al.: The Effect of Ablation Electrode Length and Catheter Tip to Endocardial Orientation on Radiofrequency Lesion Size in the Canine Right Atrium. Although the determinants of radiofrequency lesion size have been characterized in vitro and in ventricular tissue in situ, the effects of catheter tip length and endocardial surface orientation on lesion generation in atrial tissue have not been studied. Therefore, the dimensions of radiofrequency lesions produced with 4-, 6-, 8-, 10-, and 12-mm distal electrode lengths were characterized in 26 closed-chested dogs. The impact of parallel versus perpendicular catheter tip/endocardial surface orientation, established by biplane fluoroscopy and/or intracardiac echocardiography, on lesion dimensions was also assessed. Radiofrequency voltage was titrated to maintain a steady catheter tip temperature of 75°C for 60 seconds. With a perpendicular catheter tip/tissue orientation, the lesion area increased from 29 ± 7 mm2 with a 4-mm tip to 42 ± 12 mm2 with the 10-mm tip, but decreased to 29 ± 8 mm2 with ablation via a 12-mm tip. With a parallel distal tip/endocardial surface orientation, lesion areas were significantly greater: 54 ± 22 mm2 with a 4-mm tip, 96 ± 28 mm2 with a 10- mm tip and 68 ± 24 mm2 with a 12-mm tip (all P < 0.001 vs perpendicular orientation). Lesion lengths and apparent volumes were larger with parallel, compared to perpendicular tip/tissue orientations, although lesion depth was independent of catheter tip length with both catheter tip/tissue orientations. Electrode edge effects were not observed with any tip length. Direct visualization using intracardiac ultrasound guidance was subjectively helpful in insuring an appropriate catheter tip/tissue interface needed to maximize lesion size. Although atrial lesion size is critically dependent on catheter tip length, it is more influenced by the catheter orientation to the endocardial surface. This information may also be helpful in designing electrode arrays for the creation of continuous linear lesions for the elimination of complex atrial tachyarrhythmias. [source]

Gold-Tip Electrodes,A New "Deep Lesion" Technology for Catheter Ablation?

Validation of two dual fluorescence techniques for confocal microscopic visualization of resin penetration into enamel caries lesions

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 7 2009
Sebastian Paris
Abstract Fluorescence confocal microscopy is a useful tool to analyze the infiltration of enamel caries lesions with low-viscosity resins (infiltrants) in vitro. The conventionally used staining technique, which comprises dye labeling of the resin, has been shown to be limited by chromatographic separation of the resin-dye-mixture during penetration. The aim of this study was to develop an improved dual staining technique and to compare validity and reproducibility of both methods. Human molars with proximal white spots were cut across the demineralizations. After varnishing the cut surfaces, paired lesion halves were infiltrated with an infiltrant using either one of two different staining techniques. For the conventional direct technique (A) the infiltrant was labeled with rhodamine isothiocyanate (RITC) prior to application. Using the new indirect technique (B) lesions were stained with RITC solution and subsequently infiltrated with pure infiltrant. After light curing, unbound dye was bleached by immersion in hydrogen peroxide. Remaining lesion pores were stained with sodium fluorescein solution. Penetration depths (PD) and lesion depths (LD) were evaluated by five examiners using confocal microscopy and compared with the results of scanning electron microscopic (SEM; PD) and microradiographic (TMR; LD) analysis. The indirect technique showed better correlation (intraclass coefficients) with SEM (0.990) and TMR (0.982) compared with the direct technique (SEM: 0.513; TMR: 0.702). Inter- and intrarater reliability was higher for technique B compared with technique A. The new indirect technique yields to more valid and reliable results to visualize infiltrant penetration into natural enamel caries lesions compared with the conventional method. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source]