Comparison between biparietal bipolar and uniparietal bipolar radio frequency ablation techniques in a simultaneous procedural setting

Purpose

To make an in vitro evaluation of the lesion size and depth produced in two different sets of radio frequency energy bipolar delivery: simultaneous biparietal bipolar (SBB) and simultaneous uniparietal bipolar (SUB).

Methods

Two separate prototypes have been built for our purpose: one to be used in SBB mode and the other to be used SUB mode. Forty left atrium samples were taken from the hearts of freshly slaughtered pigs. They were ablated into a simulator ABLABOX, where blood flow, temperature, and contact force were controlled. After being sliced into a cryotome, the samples were digitalized by a flatbed scanner, and the images were analyzed by a computer morphometric software.

Results

Transmural lesions were achieved in 18/20 samples (90%) in SBB, while SUB showed transmurality in 9/20 samples (45%). Overall maximum diameter (D_MAX) resulted larger in SUB than in SBB (2.43?±?0.30 mm, 1.62?±?0.14 mm, respectively; p?<?0.05): Moreover, maximum epicardial and endocardial diameters (D_EPI and D_ENDO, respectively) were wider in SUB group than SBB group (2.28?±?0.30 mm, 2.26?±?0.40 and 1.60?±?0.14 mm, 1.59?±?0.15 mm, respectively; p?<?0.05). We observed the same tendency in lesion depth: The total area and volume (A_TOT and V_TOT) were broader in SUB group than in SBB one (581.01?±?65.38 mm/mm², 58.10?±?6.53 mm/mm³ and 521.97?±?73.05 mm/mm², 52.19?±?7.30 mm/mm³. respectively; p?<?0.05).

Conclusions

In contrast with the smaller lesion sizes, the biparietal bipolar group showed a higher transmurality rate. These findings may suggest a better drive of the energy flow when compared with SUB lesions.

     

Clinical and imaging characteristics of orbital leukemic tumors

PURPOSE: To characterize the clinical and imaging features of orbital leukemic tumors in 27 patients seen and treated at St. Jude Children's Research Hospital. METHODS: A retrospective review was performed on the clinical and imaging records of 27 consecutive patients with a diagnosis of orbital leukemic tumors. The following data were extracted from the patients' records: age at diagnosis of orbital leukemic tumors, sex, race, national origin, type of leukemia, temporal relationship of orbital disease to diagnosis of leukemia, survival from diagnosis of orbital leukemic tumor, laterality of the orbital disease, location of the mass within the orbit, imaging features of the mass, chemotherapeutic protocol, treatment with bone marrow transplant, and orbital radiation. RESULTS: The median age at diagnosis of orbital leukemic tumor was 8 years (range, 1-18 years). Nineteen of the 27 patients were male, and 21 patients were born and lived in the United States. Twenty-one patients had acute myeloid leukemia, five had acute lymphoblastic leukemia, and one had chronic myelogenous leukemia. In 85% of patients (n = 23), the diagnosis of leukemia was based on the bone marrow examination findings. Orbital imaging revealed homogenous masses that molded to one or more orbital walls without bony destruction. Nine patients had bilateral orbital involvement. All patients received multiagent systemic chemotherapy, and 14 underwent bone marrow transplantation. Five patients received external beam radiation for the treatment of orbital disease. Fifteen (55.6%) of the 27 patients were alive at the time of the study. The median survival for all patients was 4.75 years (range, 0.1-24 years) after the diagnosis of orbital disease. CONCLUSIONS: Orbital leukemic tumors occur most commonly in the first decade of life, in association with acute myeloid leukemia. They appear as homogenous masses along the orbital walls. Although the overall survival rate for patients with leukemia has improved over the past 3 decades, the mortality of patients who develop orbital leukemic tumors remains high.     

An in vitro comparative study of apically extruded debris resulting from conventional and three rotary (Profile, Race, FlexMaster) instrumentation techniques

Canal preparation is one of the most important stages of endodontic therapy, and various techniques have been applied for it. The present study was conducted to compare the quantity of debris extruded from the apical foramen during canal preparation during the manual technique and with the use of three rotary systems (Profile, Race, FlexMaster). One hundred single-rooted premolars were divided into four groups of 25 teeth each. For collection of debris, vials containing distilled water and weighed before canal preparation were used. Groups H, P, R and F were prepared by the manual step-back technique, and with the use of the Profile system, Race system and FlexMaster system, respectively. After canal preparation, the vials were dried thoroughly and reweighed. The difference between the weights of the vials at the two stages was taken as the debris weight. The mean debris weights were compared by one-way ANOVA. Group H had the highest mean debris weight, which was significantly different from those of the rotary groups (P < 0.001). The lowest mean debris weight was related to group R, which was significantly different from that of group F but not significantly different from that of group P. It was concluded that the Race system induces less extruded debris than the manual technique and the FlexMaster system.     

Evaluation of apically extruded debris in conventional and rotary instrumentation techniques

OBJECTIVE: The purpose of this in vitro study was to compare two common techniques, conventional and rotary instrumentation, in debris extrusion. METHODS AND MATERIALS: Two hundred mature human teeth with mature apices and less than 15 degrees of root curvature as determined by Schneider's method were selected for use. Teeth were randomly divided into four groups of 50 teeth each and prepared using step-back instrumentation and profile 4 percent Taper Series 29 rotary system at three different speeds: 1,000 rpm, 8,000 rpm and 24,000 rpm. All of the speeds were reduced by contra angle to 1/6 rpm. Extruded debris were collected on pre-weighed vials containing distilled water through the apical foramen during instrumentation. The vials were then dried in a microwave oven at 150 degrees Celsius and weighed again. The difference was recorded as "the weight of the extruded debris." Eight control vials, two for each group, were weighed and filled with distilled water, dried, and reweighed. The mean weight of extruded debris for each group was statistically analyzed. T-student, unilateral variance analysis and Pearson tests were used in this study. RESULTS: Step-back instrumentation (Group 1) produced significantly more debris than other groups. The difference in the amount of debris produced among rotary groups was not significant. CONCLUSION: Rotary technique could reduce the amount of debris extrusion.