The effect of curing with plasma light on the shrinkage of dental restorative materials

Commercially available light activated dental composites were used in this study to compare the shrinkage following curing with plasma light (Apollo95E, DMDS) and a convention halogen dental curing light (Prismetics Lite II, Dentsply). Polymerization shrinkage was determined by measuring the strain in one dimension by means of a contacting transducer. The percentage linear shrinkage were: Spectrum H = 1.84 + 0.31, P = 1.49 + 0.35*; Ana aesthetic H = 2.04 + 0.38, P = 1.85 + 0.27; Esthet.x H = 1.66 + 0.28, P = 1.69 + 0.25; Dyract AP H = 2.39 + 0.33, P = 2.18 + 0.35*; Apollo Restore H = 1.88 + 0.36, P = 1.42 + 0.33*; Surefil H = 0.88 + 0.28, P = 0.99 + 0.30 where * = significantly different, t-test at P < 0.05. The results suggested that there was less shrinkage when curing some, but not all, materials using the plasma light, although this could be attributed to a reduced level of polymerization.     

Influence of the irradiation distance and the use of cooling to increase enamel-acid resistance with Er:YAG laser

Objectives

The aim of this study was to assess the influence of irradiation distance and the use of cooling in the Er:YAG laser efficacy in preventing enamel demineralization.

Methods

84 enamel blocks were randomly assigned to seven groups (n = 12): G1: control group – no treatment, G2–G7: experimental groups treated with Er:YAG laser (80 mJ/2 Hz) at different irradiation distances with or without cooling: G2: 4 mm/2 mL; G3: 4 mm/no cooling; G4: 8 mm/2 mL; G5: 8 mm/no cooling; G6: 16 mm/2 mL; G7: 16 mm/no cooling. The samples were submitted to an in vitro pH cycles for 14 days. Next, the specimens were sectioned in sections of 80–100 μm in thickness and the demineralization patterns of prepared slices were assessed using a polarized light microscope. Three samples from each group were analyzed with scanning electronic microscopy. Analysis of variance and the Fisher test were performed for the statistical analysis of the data obtained from the caries-lesion-depth measurements (CLDM) (alpha = 5%).

Results

The control group (CLDM = 0.67 mm) was statistically different from group 2 (CLDM = 0.42 mm), which presented a smaller lesion depth, and group 6 (0.91 mm), which presented a greater lesion depth. The results of groups 3 (CLDM = 0.74 mm), 4 (CLDM = 0.70 mm), 5 (CLDM = 0.67 mm) and 7 (CLDM = 0.89 mm) presented statistical similarity. The scanning electronic microscopy analysis showed ablation areas in the samples from groups 4, 5, 6 and 7, and a slightly demineralized area in group 2.

Conclusions

It was possible to conclude that Er:YAG laser was efficient in preventing enamel demineralization at a 4-mm irradiation distance using cooling.     

Bullseye: preclinical evaluation of a novel structured light-based imaging workflow to inform glenoid implant positioning in total shoulder arthroplasty

BackgroundAccurate glenoid component positioning during total shoulder arthroplasty (TSA) is critical for prosthesis longevity and postoperative function. Glenoid component positioning in many TSA procedures depends on the insertion of a guide pin through the glenoid vault. However, up to 48% of TSA procedures involve guide pin malpositioning. The aim of this study was to evaluate the ability of a novel structured light imaging system to visualize glenoid guide pin position and trajectory in surgically exposed cadaveric shoulders. Computed tomography (CT)-based and magnetic resonance imaging (MRI)-based workflows and subchondral bone–based and glenoid cartilage–based workflows were compared.MethodsPreoperative cone-beam CT (CBCT) and MRI images were acquired for 5 intact cadaveric shoulders. Following deltopectoral surgical exposure, a glenoid vault guide pin was inserted through the glenoid vault of each scapula as in a clinical TSA procedure. A 3D printed optical tracker was placed over the guide pin, and a 3D optical surface image of the glenoid and tracker was acquired using a handheld structured light sensor. A postprocedural CBCT was acquired for each shoulder to verify guide pin position and trajectory. The imaging procedure was repeated after débridement of the glenoid cartilage to expose subchondral bone. The guide pin was segmented from the postprocedural CBCT image (actual guide pin). A virtual model of the tracker was aligned with a co-linear representation of the intraoperative guide pin (predicted guide pin). A series of image registrations aligned the actual and predicted guide pin positions to yield visualization accuracy, defined as the trajectory and offset errors between predicted and actual guide pins.ResultsThe mean guide pin trajectory and offset errors based on the subchondral bone were 2.22 ± 1.27° and 1.27 ± 0.46 mm for the CT-based workflow and 2.27 ± 1.72° and 1.78 ± 0.92 mm for the MRI-based workflow, respectively. Registration of the cartilage surface models visualized in the MRI images reduced accuracy to a trajectory error of 3.89 ± 1.57° (P = .147) and offset error of 2.28 ± 1.33 mm (P = .217).ConclusionThe Bullseye structured light imaging system presented an accurate approach for glenoid guide pin verification and adjustment during TSA using preoperative MRI or CT. Future development for the implementation of the Bullseye system should focus on improving surface segmentations and automation of the computer vision algorithm needed to facilitate clinical translation.     

早期乳腺癌前哨淋巴结活检手术中示踪方法的临床应用研究

目的对比分析核素联合亚甲蓝与亚甲蓝单示踪法在早期乳腺癌前哨淋巴结活检术中应用效果。方法收集我院385例行前哨淋巴结活检术的乳腺癌患者的临床资料,其中109例由高年资医生应用亚甲蓝单示踪法,276例由高年资和低年资两组医生应用核素联合亚甲蓝示踪法,对比分析行联合示踪法与单示踪法前哨淋巴结活检结果的差异。并分析不同年资手术医生在联合示踪法前哨淋巴结活检结果的差异。结果联合示踪法与亚甲蓝单示踪法在前哨淋巴结活检的检出率、假阴性率、准确率、灵敏率无统计学意义(P>0.05),在联合示踪法下,高年资手术医生与低年资手术医生的前哨淋巴结活检的检出率、假阴性率、准确率无显著差异(P>0.05)。结论高年资外科医生使用亚甲蓝单示踪法行前哨淋巴结活检,是安全可靠又经济的方法。联合示踪法有助于帮助年轻的乳腺外科医生快速掌握熟悉前哨淋巴结活检技术。     

达芬奇机器人周围肺磨玻璃结节术前定位指征的研究

目的探讨肺磨玻璃结节的术前定位指征。方法纳入北部战区总医院自2012年4月至2019年9月收治的192例应用达芬奇机器人手术系统切除肺部磨玻璃结节患者,男95例、女97例,平均年龄(56.47±11.79)岁。所有患者完善术前检查,按术前是否予以定位,分为定位组(n=97)和不定位组(n=95);定位组按磨玻璃实质不同分为纯磨玻璃结节(pGGO)组(n=23),混合磨玻璃结节(mGGO)组(n=74);未定位组分为pGGO组(n=14),mGGO组(n=81)。各个组又根据结节大小及与胸膜距离与能否探查及结节,得出相应的线性函数。结果术前行亚甲蓝定位组的手术时间短于不定位组手术时间。在散点图中描绘结节相对应直径和深度及能否探及到的坐标点,并对所有坐标点进行线性回归得出的线性函数[深度=0.648×直径–1.446(单位为mm)]可作为达芬奇机器人手术pGGO节术前定位的指征;线性函数[深度=0.5595×直径ᒰ0.56(单位为mm)]可作为达芬奇机器人手术mGGO术前定位的指征。结论结果提示该方程可作为临床周围肺磨玻璃结节的术前定位指征。     

Preoperative localization of sentinel lymph node in breast cancer patients by silver wire insertion or liquid charcoal injection guided by CT lymphography

Dual localization of SLN in breast cancer patients using isotope & dye is the best‐approved modality with limitations such as high cost of radioactive materials, complex logistic preparations & scheduling issues, especially in developing countries. We investigated the feasibility & accuracy of a novel technique for SLN localization using silver wire insertion or liquid charcoal injection guided by CT lymphography. 120 patients with clinically node‐negative breast cancer were enrolled. In the test group, SLN was localized using preoperative CTLG guided injection of liquid charcoal or by placing a 3 cm silver wire. In addition, intraoperative SLN mapping was performed using methylene blue dye followed by searching for the SLN localized by both methods. In the control group, SLN was localized by the blue dye only. Feasibility, accuracy, detection rates, and number of SLNs retrieved were reported as well as matching between the LN detected with the CTLG and that detected with the dye technique. SLN could be detected in 59 out of 60 patients (98.3%) in the test group and in 54 out of 60 patients (90%) in the control group (P = .057). In self‐controlled analysis of the test group comparing CTLG only to dye only was significant (P = .050). Comparing charcoal to silver wire in detection was statistically insignificant (P = .5). This novel method can offer advantages which are as follows: being more accurate than the dye alone, saving operative time, abandoning complex logistic preparations for the radioisotope, and solving the problem of timing.