Mean Lesion Depth Research Articles

In vitro characterization of radiofrequency ablation lesions in equine and swine myocardial tissue

Radiofrequency ablation is a promising technique for arrhythmia treatment in horses. Due to the thicker myocardial wall and higher blood flow in horses, it is unknown if conventional radiofrequency settings used in human medicine can be extrapolated to horses. The study aim is to describe the effect of ablation settings on lesion dimensions in equine myocardium. To study species dependent effects, results were compared to swine myocardium. Right ventricular and right and left atrial equine myocardium and right ventricular swine myocardium were suspended in a bath with circulating isotonic saline at 37 °C. The ablation catheter delivered radiofrequency energy at different-power-duration combinations with a contact force of 20 g. Lesion depth and width were measured and lesion volume was calculated. Higher power or longer duration of radiofrequency energy delivery increased lesion size significantly in the equine atrial myocardium and in equine and swine ventricular myocardium (P < 0.001). Mean lesion depth in equine atrial myocardium ranged from 2.9 to 5.5 mm with a diameter ranging from 6.9 to 10.1 mm. Lesion diameter was significantly larger in equine tissue compared to swine tissue (P = 0.020). Obtained data in combination with estimated wall thickness can improve lesion transmurality which might reduce arrhythmia recurrence. Optimal ablation settings may differ between species.

Efficacy of balloon-expandable extreme-low-temperature ventricular epicardial cryoablation: A preclinical proof of concept evaluation

BackgroundCurrent epicardial ablation technologies are limited by the inability to create adequate depth lesions and risk of collateral injury to extracardiac structures. ObjectiveThe purpose of this study was to evaluate the feasibility and efficacy of ventricular epicardial ablation with a novel balloon-expandable extreme-low-temperature (XLT) cryoablation catheter with an embedded insulation pontoon for protection of extracardiac structures, which has been specifically designed for epicardial ablation. MethodsTen healthy swine underwent surgical (n = 6) and subxiphoid percutaneous (n = 4) epicardial access. A total of 3–6 sites were targeted in the right and left ventricular wall for different exposure durations. Ablation was performed with a large footprint (surgical) and smaller footprint (percutaneous) version of the HeartPad (Corfigo Inc., Montclair, NJ) XLT system. The system consists of the balloon-expandable cryoablation catheter and a console. The console vaporizes liquid helium (–269°C) and controls continuous delivery of extremely cold helium gas at high flow rates through a high-efficiency ablation element mounted on an expandable insulation pontoon to protect extracardiac structures. Ablation lesions were assessed by gross pathology and histologic examination. ResultsA total of 42 epicardial lesions were created. Mean lesion depth increased progressively with ablation time (surgical catheter: 11 ± 2 mm at ≤30 seconds, 13 ± 4 mm at 60 seconds, 15 ± 3 mm at ≥120 seconds, P = .001; percutaneous catheter: 10 ± 2 mm at 30 seconds, 14 ± 2 mm at 60 seconds, 16 ± 2 mm at 120 seconds, P = .001). Lesion geometry seemed unaffected by presence and thickness of epicardial fat. One episode of ventricular fibrillation occurred after ablation over the atrioventricular groove and 2 adjacent obtuse marginal arteries. ConclusionSurgical or percutaneous epicardial ablation using the HeartPad XLT cryoablation system is feasible and can efficiently produce deep ventricular lesions in different epicardial locations.

Development of an Artificial White Spot Lesion Creation Protocol: A Preliminary Study.

Protocols that determine the lesion depth of specific demineralization solutions are lacking. This in vitro study aimed to evaluate various lesion depths of artificial white spot lesions (WSLs) at different exposure times. Materials and methods: Artificial WSLs were created by placing 30 extracted human premolar teeth into 0.05M acetate buffer solution with a controlled environment of pH 4.4 at 37ºC, which were then exposed in the solution for various durations of 4, 5, 6, 8, 10, and 12 days. The specimens were visually examined using theEkstrand-Ricketts-Kidd (ERK) system to confirm the WSL, followed by buccolingual sectioning, and evaluated under a scanning electron microscope (SEM) to measure the lesion depth. The SEM showed that the mean lesion depths of representative specimens were 101.33 µm (day 4), 124 µm (day 5), 159 µm (day 6), 187 µm (day 8), 202 µm (day 10), and 212 µm (day 12). The artificial WSL was visually demonstrated in grades 1 and 2 of the ERK system. The depths of the lesions increased as the duration increased from day 4 to day 12, indicating that the lesion depths increased with the more prolonged exposure to the acetate buffer solution.

Evaluation of resin infiltration for inhibiting initial caries progression: An in vitro study using Micro-Computed Tomographic analysis

ObjectiveTo evaluate the changes in lesion depth and mineral density of resin infiltration-treated white spot lesions against asimulated oral environment using thermal and acidic challenges in vitro. Materials and methodsTwo enamel slabs were prepared from each buccal surface of permanent human premolars, for a total of 56 slabs. Artificial white spot lesions were induced. One specimen was treated with resin infiltration, while the other was used as an untreated control. A micro-CT was used to assess the lesion depth and mineral density of each specimen. Subsequently, all specimens were subjected to 10,000 cycles of thermocycling and pH cycling for 10 days before being re-evaluated using the micro-CT. Lesion depth and mineral density were examined and compared between before and after aging procedures within each group by the paired sample t-test. The independent samples t-test was utilized to compare lesion depth progression and percentage change of mineral density between groups. ResultsAfter aging, there was both a significant lesion depth progression and a mineral loss in the control and resin infiltration groups. Mean lesion depth progression was 132.88 ± 4.18 µm for the control group and 52.31 ± 4.16 µm for resin infiltration group. Percentage mineral density loss as a percentage for the control and resin infiltration groups were 16.1 ± 0.64 % and 8.83 ± 0.30 %, respectively. The resin infiltration group demonstrated a significantly lower mean lesion depth progression and percentage changes in mineral loss compared to the control group. ConclusionsThe lesion depth and mineral density changes in the resin infiltrated-treated group were lower than untreated white spot lesions after aging procedures using thermal and acidic challenges. Clinical significanceResin infiltration is a promising approach to inhibit the progression of white spot lesions related to the initial stage of dental caries.

Effect of CO2 Laser-Assisted Titanium Tetra-fluoride on Demineralization of Enamel Around Orthodontic Brackets.

Introduction: One of the clinical problems following orthodontic treatment is white spot lesions around orthodontic brackets due to enamel demineralization. Confronting enamel demineralization during fixed treatments has long been a challenge for orthodontists. The aim of this in vitro study was to evaluate the effect of CO2 laser and Titanium Tetra-fluoride (TiF4) application on the prevention of enamel demineralization around orthodontic brackets. Methods: Eighty permanent premolars were selected and bonded with brackets. They were randomly divided into four groups (n=20): topical titanium tetra-fluoride gel 4% (TiF4), CO2 laser (10.6 μm wavelength for 10 seconds, peak power=291 W), fluoride+laser (F+L) and control (C). All specimens were demineralized for 10 days in a 0.2 M acetate buffer solution. The mean lesion depths were determined by using polarized light microscopy. Results: The mean depth of lesion was the highest in the C group and then decreased in the TiF4, CO2 laser, and F+L groups, respectively. The difference between all groups was significant (P<0.05), except for the CO2 laser and F+L groups. Conclusion: The lowest amount of demineralization around the orthodontic brackets was observed in the L+F group, followed by the CO2 laser, TiF4, and control groups, respectively.

Evaluation of force time integral, force time current integral and lesion size index in a new force sensing catheter

Abstract Funding Acknowledgements Type of funding sources: None. Background Radiofrequency current remains one of the most important ablation techniques in the EP lab. Creating durable lesions is key to successful ablation. Evaluating lesion quality and progression of lesion growth is difficult as many parameters influence lesion formation. Therefore, several approaches were developed, as monitoring RF duration, power and contact force seems insufficient in clinical practice. Force-time-integral (FTI) and force-time-current-integral (FTCI), as well as the ablation index (AI) and lesion size index (LSI) showed decent results in past studies. Recently, a new force sensing catheter (NFSC) was released. By now, data about lesion formation and correlation with the FTI, FTCI and LSI is lacking with this NFSC. This study aimed to further investigate lesion formation with the NFSC in an ex vivo model. Methods 30 RF-lesions were created using an ex vivo porcine cardiac model with the NFSC catheter. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. In a first set of lesions, CF was varied (1g, 5g, 10g, 20g). Three lesions were created in each CF-level with 30W. In a second set of lesion, CF was kept at 10 – 15 g, but ablation power was set to 20W, 30W, 40W, 50W, 60W and 70W. In every power level, three lesions were created. All parameters (power, temperature, global impedance, contact force, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped. Results 1640 measurement in 30 lesions were included into the analysis. Mean lesion diameter was 7.82 ± 1.52 mm, mean lesion depth 4.80 ± 1.08 mm. Baseline global impedance (GI) was 138.10 ± 10.93 Ω, mean GI-drop 28.10 ± 8.00 Ω. In average, CF of 12.10 ± 5.87 g was used. Correlations of lesion size, FTI and FTCI are shown in table 1. Interestingly, LSI correlated best with lesion size (r = 0.851 and r = 0.852 for lesion depth and diameter; p&amp;lt;0.001). Figure 1 illustrates a scatter plot of LSI and lesion depth (Figure 1a) and lesion diameter (Figure 1b). Figure 2 shows dynamic changes in lesion depth compared to changes in LSI and FTCI. During RF-application, development of lesion formation and LSI is comparable from approximately second 7 onwards. FTCI is rising in a linear manner, whereas lesion formation increases monoexponentially. Conclusion In the NFSC, lesion size correlates strongest with the LSI in power levels up to 70 Watts. FTI and FTCI also showed decent correlations. Regarding dynamic changes in lesion size, LSI is best comparable to actual lesion growth.

Monitoring lesion activity on primary teeth with CP-OCT and SWIR reflectance imaging.

The purpose of this study was to use cross polarization optical coherence tomography (CP-OCT) and short wavelength infrared imaging (SWIR) reflectance imaging to monitor changes in the structure and activity of early occlusal caries on primary teeth over a period of 6 months during intervention with fluoride. Participants (n = 29) aged 6-10 each with two suspected active occlusal lesions on primary teeth completed the study. Fluoride varnish was applied to tooth surfaces every 3-months and participants were instructed to brush twice daily with a fluoride toothpaste. Images were acquired using CP-OCT every 3 months for 6 months. SWIR reflectance images were acquired during forced air-drying of the lesions for 30 s at 0 and 6-months. Most of the 42 lesions appeared initially active at baseline. Only 6 lesions appeared arrested at baseline based on the presence of a highly mineralized transparent surface layer (TSL) in CP-OCT images. At 6 months, 14 of the lesions appeared arrested including the 6 initially arrested lesions and the TSL thickness increased significantly (p < 0.0001). The mean lesion depth (Ld) and the integrated reflectivity over the lesion depth (ΔR) increased significantly (p < 0.05) after 6 months for the 42 lesions analyzed. SWIR reflectance images showed that there was a significantly higher (p < 0.05) delay before changes in intensity were measured for active lesions versus arrested lesions during lesion drying. CP-OCT was able to monitor changes in lesion structure and activity including the formation of a highly mineralized TSL indicative of lesion arrest during nonsurgical intervention. Time-resolved SWIR reflectance imaging also shows that there are differences in the dehydration kinetics between active and arrested lesions. This study demonstrates two independent imaging methods that can be used to monitor changes in lesion activity over time.

Comparative evaluation of prevention of demineralization of artificial enamel caries treated with two fluoride varnishes and 38% SDF in primary teeth: an in vitro study

BackgroundThis study aimed to compare the effect of Clinpro™ White varnish containing 5% sodium fluoride (NaF) and functionalized tricalcium phosphate, MI varnish containing 5% NaF and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and 38% Silver diamine fluoride (SDF) in preventing demineralization of treated white spot lesions (WSLs) in enamel of primary teeth.MethodsForty-eight primary molars with artificial WSLs were allocated into four groups as follows: Group 1: Clinpro white varnish, Group 2: MI varnish, Group 3: SDF, and Group 4: control (no treatment). The three surface treatments were applied for 24 h and then enamel specimens were subjected to pH cycling. Thereafter, the mineral content of specimens was evaluated by Energy Dispersive X-ray Spectrometer and the lesion depth was assessed via Polarized Light Microscope. One-way ANOVA followed by Tukey’s post hoc test were used at p ≤ 0.05 to identify significant differences.ResultsInsignificant difference in mineral content was observed among treatment groups. Treatment groups exhibited significantly higher mineral content compared to control except for Fluoride (F). MI varnish showed the highest mean calcium (Ca) ion content (66.57 ± 0.63), and Ca/P (2.19 ± 0.11), followed by Clinpro white varnish, and SDF. MI varnish also displayed the highest phosphate (P) ion content (31.46 ± 0.56), followed by SDF (30.93 ± 1.02), and Clinpro white varnish (30.53 ± 2.19). Fluoride content was highest in SDF (0.93 ± 1.18), followed by MI (0.89 ± 0.34) and Clinpro (0.66 ± 0.68) varnishes. Significant difference in lesion depth was observed among all groups (p < 0.001). The lowest mean lesion depth (µm) was found in MI varnish (226.23 ± 44.25) which was significantly lower than Clinpro white varnish (285.43 ± 44.70), SDF (293.32 ± 46.82), and control (576.69 ± 42.66). Insignificant difference in lesion depth was found between SDF and Clinpro varnish.ConclusionsIn primary teeth, WSLs treated with MI varnish displayed better resistance to demineralization compared to WSLs treated with Clinpro white varnish and SDF.

Recombinant amelogenin peptide TRAP promoting remineralization of early enamel caries: An in vitro study.

Objective: To explore the regulatory effect of recombinant amelogenin peptide TRAP on the remineralization of early enamel carious lesions. Methods: Forty-eight bovine enamel blocks that prepared initial lesions in vitro were split at random into four groups for immersion treatment for 12days: 1) remineralizing medium; 2) studied peptide 1 (consisting of the N- and C-termini of porcine amelogenin) + remineralizing medium; 3) studied peptide 2 (TRAP) + remineralizing medium; 4) fluoride + remineralizing medium. After demineralization and remineralization immersion, each specimen's mean mineral loss and lesion depth were measured using micro-computed tomography (micro-CT). The changes in lesion depth (∆LD) and mineral gain (∆Z) were computed following remineralization. The enamel samples were then cut into sections and examined with polarized light microscopy (PLM). The cross-section morphology was observed by scanning electron microscopy (SEM). The crystal phase was analyzed by an X-ray micro-diffractometer (XRD). The calcium-binding properties were determined using isothermal titration calorimetry (ITC). Results: Micro-CT analysis revealed a significant reduction in mineral loss in the four groups following the remineralization treatment (p < 0.05). The treatment with fluoride resulted in the greatest ∆Z and ∆LD, whereas the treatment with a remineralizing medium showed the least ∆Z and ∆LD among all groups. The ∆Z and ∆LD of the studied peptide 1 and studied peptide 2 groups were greater than those of the remineralizing medium group. However, there was no significant difference between the studied peptide 1 and studied peptide 2 groups (p > 0.05). All of the samples that the PLM analyzed had a thickening of the surface layer. A negative birefringent band changed in the lesion's body. The SEM displayed that minerals were formed in all four groups of samples. The XRD results indicated that the products of remineralization of the studied peptide were hydroxyapatite crystals (HA). ITC showed that there were two binding modes between the calcium and peptide TRAP. Conclusion: This study confirmed the potential of the recombinant amelogenin peptide TRAP as a key functional motif of amelogenin protein for enamel remineralization and provided a promising biomaterial for remineralization in initial enamel carious lesion treatment.

Effect of contact force on pulsed field ablation lesions in porcine cardiac tissue.

Contact force has been used to titrate lesion formation for radiofrequency ablation. Pulsed field ablation (PFA) is a field-based ablation technology for which limited evidence on the impact of contact force on lesion size is available. Porcine hearts (n = 6) were perfused using a modified Langendorff set-up. A prototype focal PFA catheter attached to a force gauge was held perpendicular to the epicardium and lowered until contact was made. Contact force was recorded during each PFA delivery. Matured lesions were cross-sectioned, stained, and the lesion dimensions measured. A total of 82 lesions were evaluated with contact forces between 1.3and 48.6 g. Mean lesion depth was 4.8 ± 0.9 mm (standard deviation), mean lesion width was 9.1 ± 1.3 mm, and mean lesion volume was 217.0 ± 96.6 mm3 . Linear regression curves showed an increase of only 0.01 mm in depth (depth = 0.01 × contact force + 4.41, R2 = 0.05), 0.03 mm in width (width = 0.03 × contact force + 8.26, R2 = 0.13) for each additional gramof contact force, and 2.20 mm3 in volume (volume = 2.20 × contact force + 162, R2 = 0.10). Increasing contact force using a bipolar, biphasic focal PFA system has minimal effects on acute lesion dimensions in an isolated porcine heart model and achieving tissue contact is more important than the force with which that contact is made.

A comparative study of two chemical models for creating subsurface caries lesions on aprismatic and prismatic enamel.

To investigate the mineral density and lesion depth of artificial caries lesions on aprismatic enamel and prismatic enamel created by lactic acid and acetic acid buffers. Forty bovine enamel blocks were allocated to: aprismatic enamel (Group A) and prismatic enamel (Group C) in acetic acid buffer for 192 h and aprismatic enamel (Group B) and prismatic enamel (Group D) in lactic acid buffer for 96 h. The mineral loss and lesion depth were measured using micro-computed tomography. A significant difference (P = 0.01) was observed in the mineral loss (%) in the lesions on aprismatic enamel and prismatic enamel treated with lactic acid buffer while no significant difference (P = 0.51) was observed in the mineral loss (%) in the lesions on aprismatic enamel and prismatic enamel treated with acetic acid buffer. No significant difference was noted in the mean lesion depth of lesions on aprismatic enamel and prismatic enamel treated with acetic acid and lactic acid buffers (P > 0.05). Aprismatic enamel and prismatic enamel have similar mineral loss in acetic acid while prismatic enamel showed more mineral loss compared to aprismatic enamel in lactic acid.

Effect of strontium-doped bioactive glass-ceramic containing toothpaste on prevention of artificial dentine caries formation: an in vitro study

BackgroudRoot caries in aging population was prevalent worldwide. Due to the absence of enamel and specific structure of dentine, bacteria are able to penetrate further into dentine at an earlier stage of lesion development. The aim of this study was to investigate the effect of adding of a strontium-doped bioactive glass-ceramic (HX-BGC) to a fluoride-free toothpaste on prevention of formation of artificial dentine caries.MethodsThirty-six human tooth specimens were allocated to three groups (n = 12 per group). Group 1 treated with slurry containing a fluoride-free toothpaste and 5% HX-BGC, Group 2 was treated with fluoride-free toothpaste slurry, and Group 3 received deionized water as a negative control. The specimens were subjected to four cycles (15 h demineralization and 8 h remineralization for one cycle) of biochemical cycling. A mixed suspension of five bacteria species (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Actinomyces naeslundii) were prepared in brain heart infusion broth with 5% sucrose and used as acidic challenge in biochemical cycling. Subsequently, surface morphology of the dentine lesion was assessed by scanning electron microscopy, while the lesion depths and mineral loss were assessed by micro-computed tomography.ResultsThe mean lesion depths in dentine in Groups 1 to 3 were 87.79 ± 16.99 μm, 101.06 ± 10.04 μm and 113.60 ± 16.36 μm, respectively (p = 0.002). The mean amounts of mineral loss in Groups 1 to 3 were 0.82 ± 0.10 g/cm3, 0.89 ± 0.09 g/cm3 and 0.96 ± 0.11 g/cm3, respectively (p = 0.016). No obvious differences in the surface morphology were seen among the groups.ConclusionAddition of strontium-doped bioactive glass-ceramic to fluoride-free toothpaste has potential to reduce formation of dentine lesions.

Remineralizing Potential of Low-fluoridated, Nonfluoridated and Herbal Nonfluoridated Dentifrices on Demineralized Surface of Primary Teeth: An In Vitro Study.

AimThe aim of this in vitro study is to evaluate the remineralizing potential of commercially available low-fluoridated, nonfluoridated, and herbal nonfluoridated child formula dentifrices on primary teeth.Materials and methodsTotal of 36 primary teeth were placed in the demineralizing solution for 96 hours to produce artificial carious lesions of approximately 100 μm depth, and then cut longitudinally into 30 sections of 100–150 μm thickness and randomly assigned to three groups. Sections were treated with low-fluoridated, nonfluoridated, and herbal nonfluoridated dentifrice. Lesions were evaluated using polarized light microscopy.ResultsIntragroup comparison of mean lesion depth from pretreatment to posttreatment among the three study groups revealed that maximum reduction in lesion depth was found to be in group I (low-fluoridated) followed in descending order by group III (herbal nonfluoridated) and group II (nonfluoridated), respectively.ConclusionGroup I (low-fluoridated) and group III (herbal nonfluoridated) demonstrated remineralization of carious lesions by virtue of a decrease in lesion depth, whereas group II (nonfluoridated) showed an increase in lesion depth.Clinical significanceFluoride dentifrices are the most widely used products that deliver topical fluoride to the oral environment. The major drawback is the risk of dental fluorosis, which occurs because of ingestion of dentifrices, in preschool children. This necessitates use of preventive measures which include (1) reducing the amount of toothpaste used, (2) supervised brushing in preschool children and (3) developing low-fluoride toothpastes for minimizing risk of dental fluorosis. Further dental professionals must investigate effectiveness of increasingly popular “Herbal” products.How to cite this articleTiwari S, Saha S, Dhinsa K, et al. Remineralizing Potential of Low-fluoridated, Nonfluoridated and Herbal Nonfluoridated Dentifrices on Demineralized Surface of Primary Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(3):251-257.

Evaluation of linear lesion formation and thermodynamics by dragging ablation with the third-generation laser balloon.

BackgroundThe lesion formation properties of a motorized rotational delivery (RAPID) mode, third-generation laser balloon (LB3) ablation compared to point-by-point laser ablation in patients with atrial fibrillation remain unclear.ObjectiveThe purpose of this study was to assess lesion characteristics and thermodynamics in LB3 ablation with a RAPID mode in vitro model.MethodsChicken muscles were cauterized using LB3 in RAPID mode with 13 W and 15 W and 50% overlapped point-by-point fashion with 7 W/30 seconds, 8.5 W/20 seconds, 10 W/20 seconds, and 12 W/20 seconds. Lesion depth, width, and continuity were compared. Lesion continuity was classified by the visible gap degree categorized from 1 (perfect) to 3 (poor). Thermodynamics and maximum tissue temperatures were assessed under infrared thermographic monitoring. Fifteen and 5 lesions were evaluated per ablation protocol for measurement of lesion size and continuity and for thermographic assessment, respectively.ResultsLesion depth and width were smaller in RAPID mode laser ablation than point-by-point laser ablation (P <.001). However, RAPID mode laser ablation revealed sufficient mean lesion depth of 5 mm or more. Lesion continuity was 1 (perfect) in all samples in RAPID mode laser ablation and point-by-point laser ablation (P = 1). Infrared thermographic observation demonstrated fast and gapless linear lesion formation with thermal stacking in RAPID mode laser ablation. Maximum tissue temperature was lower in RAPID mode laser ablation than point-by-point laser ablation (P <.001).ConclusionRAPID mode LB3 ablation could provide fast, gapless, and acceptable lesion formation with thermal stacking and moderate tissue temperature rise.

Outcomes of bone marrow aspirate concentrate and matrix-induced chondrogenesis (BMIC) for treatment of osteochondral lesions of the talus

BackgroundTo analyze the outcomes of Bone marrow aspirate concentrate and Matrix-Induced Chondrogenesis (BMIC) in Osteochondral Lesions of the Talus (OLTs). MethodsPatients with OLTs treated with BMIC from June 2013 to July 2020 were included. Visual Analogue Scale (VAS), Foot Function Index (FFI), and Foot Ankle Outcome Score (FAOS) before treatment and at last follow-up were subjected to analysis. ResultsForty-five patients were included and mean follow-up was 39.1 months (range, 13–97 months). Mean lesion size and depth were 180.7 ± 110.4 mm2 and 9.6 ± 3.7 mm, respectively. BMIC was performed without malleolar osteotomy in 36 patients (80%) and bone graft was performed in 42 (93.3%). VAS, FFI, and FAOS improved significantly. No complication occurred and no revision was required. ConclusionsThe BMIC procedure is feasible and should be considered a viable treatment option for OLTs associated with large subchondral bone defects.

Measuring peri-implant bone lesions using low-dose cone-beam computed tomography.

High-definition cone-beam computed tomography (HD-CBCT) offers superior image quality at the cost of higher radiation dose compared to low-dose CBCT (LD-CBCT). The aim of this study was to investigate whether peri-implant bone lesions can be accurately quantified using LD-CBCT, even when including the influence of surrounding tissues. Twelve titanium implants restored with all-ceramic crowns were placed in bovine bone, and peri-implant lesions were prepared. Radiographic imaging was performed using IR (intraoral radiography), HD-CBCT and LD-CBCT. To simulate the in-vivo situation, the samples were placed inside a dry human mandible, and a second LD-CBCT imaging was performed (LD-CBCT*). The datasets were presented to four observers in random order. Maximum lesion depth and width were measured in a standardized mesiodistal slice in IR, HD-CBCT, LD-CBCT, and LD-CBCT*. Mean lesion depth and width measurements for each sample in HD-CBCT served as reference. Interrater agreement was slight for depth and excellent for width in HD-CBCT and both LD modes. For all observers, measurement deviations from HD-CBCT were below 0.3 mm in the LD protocols (LD-CBCT depth: 0.22 ± 0.17 mm, width: 0.22 ± 0.13 mm; LD-CBCT* depth: 0.24 ± 0.23 mm, width: 0.25 ± 0.21 mm) and at 0.4 mm in IR. Absolute differences between LD-CBCT and HD-CBCT are small, although surrounding tissues decrease LD-CBCT image quality. Within the limitations of an in-vitro trial, LD-CBCT may become an adequate imaging modality for monitoring peri-implant lesions at a substantially decreased radiation dose.

Characterization of white spot lesions formed on human enamel under microcosm biofilm for different experimental periods.

The initial characteristics of white spot lesion (WSLs), such as the degree of integrated mineral loss (ΔZ), depth and pattern of mineral distribution, have an impact on further demineralization and remineralization. However, these lesion parameters have not been evaluated in WSLs produced from microcosm biofilms.Objective:This study characterized artificial white spot lesions produced on human enamel under microcosm biofilm for different experimental periods.Methodology:In total, 100 human enamel specimens (4x4mm) were assigned to 5 distinct groups (n=20/group) differing according to the period of biofilm formation (2, 4, 6, 8 or 10 days). Microcosm biofilm was produced on the specimens from a mixture of human and McBain saliva at the first 8h. Enamel samples were then exposed to McBain saliva containing 0.2% sucrose. WSLs formed were characterized by quantitative light-induced fluorescence (QLF) and transverse microradiography (TMR). Data were analyzed by ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p<0.05).Results:A clear time-response pattern was observed for both analyses, but TMR was able to better discriminate among the lesions. Regarding QLF analysis, median (95%CI; %) changes in fluorescence ∆Z were -7.74(-7.74:-6.45)a, -8.52(-8.75:-8.00)ab, -9.17(-10.00:-8.71)bc, -9.58(-10.53:-8.99)bc and -10.01(-11.44:-9.72)c for 2, 4, 6, 8, and 10 days, respectively. For TMR, median (95%CI; vol%.µm) ∆Z were 1410(1299-1479)a, 2420(2327-2604)ab, 2775(2573-2899)bc, 3305(3192-3406)cd and 4330(3972-4465)d, whereas mean (SD; µm) lesion depth were 53.7(12.3)a, 71.4(12.0)a, 103.8(24.8)b, 130.5(27.2)bc, 167.2(39.3)c for 2, 4, 6, 8 and 10 days, respectively.Conclusion:The progression of WSLs formed on human enamel under microcosm biofilm can be characterized over 2-10 days, both by QLF and TMR analyses, although the latter provides better discrimination among the lesions.

Efficacy of 30% and 38% Silver Diamine Fluoride in Arresting Caries Lesions After Different Application Times: An in Vitro Study

Objective: To evaluate the efficacy of silver diamine fluoride (SDF) in arresting dentin caries lesions when applied under different concentrations and times. Material and Methods: Forty-two bovine blocks were selected and fixed in 24-well plates. Each well received a mixed bacterial inoculum added to the culture medium with 5% sucrose. The plates were incubated in microaerophilia (7 days) for caries formation, confirmed by micro-CT (M1). SDF was applied over the carious lesions for different times and concentrations (n=6): SDF 30% - immediate removal, 1 minute and 3 minutes; SDF 38%, - immediate removal, 1 minute and 3 minutes. The group without treatment was the control. Then, the samples were again scanned by micro-CT (M2) and submitted to a second cariogenic challenge for 21 days. Then, a final scan was performed (M3). Results: Mean pH at the culture medium and lesion depth were compared using Kruskal-Wallis and Wilcoxon tests. 38% SDF showed the lowest metabolic activity of the biofilm. All 38% groups and 30% 1 and 3 minutes did not show an increase in mean lesion depth comparing M3 with M1. However, only 30% 3 minutes and 38% 1 and 3 minutes showed a significant reduction of lesion depth. Conclusion: The minimum application time of 30% SDF to arrest dentin caries lesion was 1 minute, while 38% SDF arrested with application and immediate removal.

60 - Temporal Assessment of Remineralizing Demineralized Enamel Using Micro-Computed Tomography

Remineralizing enamel is an important approach of treating early carious lesion without surgical intervention allowing for preservation of tooth structure. This study objective is longitudinal assessment of enamel microstructure using non-destructive micro-CT to monitor the remineralization process undergoing fluctuating changes in pH after treatment with different remineralization agents. Twelve human extracted premolars were collected. Calculus and soft tissue were removed from the root, kept in distilled water, and stored at 4 C. The teeth were screened using Swept Source OCT (SANTEC IVS-2000) to identify a 3 ×3 mm2 caries-free region of interest on the crown for artificial caries induction. The whole crown, except for the identified sound area, was coated with two layers of acid-resistant nail varnish. Then samples were mounted using acrylic resin and customized mounts to standardize successive scans with micro-Ct. Each mounted sample was incubated in 20 ml of buffered lactic acid (2.2 mM CaCl 2 , 2.2 mM K 2 HPO 4 , 0.1 M Lactic acid adjusted pH to 4.5) for 72 hours in 37 C to induce caries-like lesions of approximately 100 micron in depth. After 72 hours, the samples were rinsed with deionized water and stored in distilled water to be scanned. The samples were grouped into four groups (n=3) that consist of three intervention groups and one negative control group. The 3 intervention groups consist of two fluoride varnish and one polypeptide-based remineralization agents. Each sample received the remineralizing treatment after the lesion formation according to manufacturers instructions. After that all samples were subjected to pH cycling for 2 weeks in 37 C incubation on a shaker table. Ph cycling solutions were refreshed at the end of every cycle following [ten Cate and Duijsters, 1982] protocol which is: 1-three hours in demineralization solution,2-rinse for 30 s with distilled water and 3- 21 hours in artificial saliva.Micro-Ct scans were carried out after 6 and 12 pH cycles. Lesion depth, ld and Delta Z, ΔZ were calculated The mean lesion depth developed in the different groups showed no noticeable difference after 6 ph. cycles while after 12 ph. cycles lesion depth were decreased in the different groups with more observable decrease in the experimental fluoride group. Both self-assembly peptide agent and experimental fluoride showed no further increase in the lesion depth after the acidic challenge at the end of the ph. cycles. Remineralized enamel with different remineralizing agents reacts differently under the same fluctuating ph. conditions at different time intervals.

Characterization of sound enamel and natural white spot lesions

Objective: To compare optical, morphological, chemical, and physical aspects of the sound enamel and whitespot lesions (WSL) classified as ICDAS 2. Material and Methods: Seventeen human molars with one surfacepresenting WSL and a sound surface (2 x 2 mm window) were characterized by Quantitative light-inducedfluorescence (QLF®), Optical coherence tomography (OCT), microhardness, and Raman spectroscopy. The ANOVAand Tukey’s test were used at 5% significance level. Results: The QLF comparison between distinct substratesyielded decreased Q (integrated fluorescence loss) of -15,37%mm2 and -11,68% F (fluorescence loss) forWSL. The OCT detected mean lesion depth of 174,43 um. ANOVA could not detect differences in the opticalattenuation coefficient between the substrates (p&gt;0.05). Lower microhardness measures were observed in WSLthan on sound enamel (p&lt;0.05). The Raman spectra showed four vibrational phosphate bands (v1, v2, v3, v4),where the highest peak was at 960.3 cm-1 (v1) for both substrates. However, a 40% decrease in phosphate (v1)was detected in WSL. The peak at 1071 cm-1 was higher for sound enamel, indicating the presence of a phosphateband instead of the B-type carbonate. The spectra showed higher intensity of the organic composition at 1295 cm-1and 1450 cm-1 for WSL. Conclusion: Non-invasive QLF, OCT and Raman spectroscopy were able to distinguishdifferences in fluorescence, optical properties, and organic/inorganic components, respectively, between soundenamel and WSL, validated by the destructive microhardness analysis. KEYWORDSDental caries; Dental enamel; White-spot lesions; Diagnosis; Raman Spectroscopy.