An in Vitro Analysis to Evaluate Coronal Residual Dentine Thickness after Different Anterior Crown Preparations

Background: Knife edge, chamfer, and shoulder are the three distinct finishing lines utilized in crown preparations. Each finishing line has relative benefits and drawbacks. However, not much scientific data exists regarding which of these finishing lines will leave the most amount of residual dentine coronally on maxillary lateral incisors and mandibular incisors. Objective: To assess the coronal residual dentine thickness after different cervical finishing lines for anterior crown preparations. Materials and Methods: A prospective comparative study was conducted including mandibular incisors and maxillary laterals that were taken from subjects from 18 to 30 years old. Teeth in each of the three groups were randomly separated into three cervical margin preparation groups: knife edge, chamfer and shoulder. The teeth were then prepared for single crown coverage using these finishing lines. The teeth were sectioned halfway through the crown preparation, and a digital caliper was used to determine the residual dentine thickness at the buccal, lingual, mesial and distal areas. The Tukey test was used for mean comparison, and ANOVA analysis was used to evaluate the variation in mean residual dentine thickness. Results: For upper lateral incisors, knife edge finishing lines showed the highest amount of remaining dentine thickness—1.5 mm. lingually, while the upper lateral incisors mesially had the least amount of 0.53 mm for shoulder finishing lines. The least residual dentine (0.53 mm for the shoulder and 0.70 mm for the chamfer finishing line) was found in the interproximal portions of all the teeth that were selected. Lower central incisors had the least amount of residual dentine 0.61 mm for shoulder preparations mesially whiles lower lateral incisors had the least amount of residual dentine for shoulder preparations 0.58 mm distally. There was a statistically significant difference of 0.001 across the groups. Conclusion: The thickness of residual dentine seen coronally after the three finishing line preparations showed a statistically significant difference and the knife edge finishing line provided enough coronal protection within the scope of this study.

Distribution of Inherent Strains and Residual Stressesin Medium Thickness Plate Weldment

A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. Distribution of inherent strains and longitudinal residual stresses in medium thickness plate weldment is calculated and analyzed. A new method of calculating inherent strains and longitudinal residual stresses is proposed.

Effect of Single- versus Double-Layer Uterine Closure during Caesarean Section on Niche Formation and Menstrual Irregularity

Background: The myometrium at the location of the CS (caesarean section) scars, also known as residual myometrium thickness (RMT), is larger after a double-layer uterine closure procedure than following a single-layer one. It may lessen the formation of a niche that is the myometrium’s disruption at the location of the scar of the uterus. Gynecological manifestations, obstetric problems in a future pregnancy and birth, and maybe subfertility are linked to thin RMT and a niche. Objective: To ascertain if double-layer unlocked closure of the uterus is better than single-layer one in terms of post-menstrual spotting and niche development following a first CS. Patients and Methods: In this randomized clinical study, 287 patients were evaluated for qualifying. Of all eligible individuals, 57 patients were excluded from the study based on the inclusion criteria. Results: The variation in ages, gestational age, body mass index (BMI), and cesarean section indications between the two assigned groups is statistically insignificant. However, postmenstrual spotting was statistically significantly more common in single-layer group compared to in double-group. The current study revealed ultrasound findings suggestive of niche formation was statistically significantly more common in single-layer group compared to in double-layer group. Conclusion: As evident from the current study, it demonstrates the advantages of double-layer unlocked closure of the uterus over single-layer one in terms of post-menstrual spotting and niche development following first-time cs. Thus, we deduced that fewer niches are formed, and fewer menstrual spotting occurs in the presence of double unlocked layers closure. To ascertain the impact of uterus closure method on post-operative niche development and the risk of obstetrics and gynaecological problems, further prospective trials with extended follow-up periods are required.

Ultrasound Evaluation of Caesarean Scar of Prelabour and Labour Caesarean Sections: A Cross Sectional Analytical Study

Caesarean section is dramatically increased throughout the world in recent years. Rupture of the uterus is a devastating complication in trial of labour following previous Caesarean section. Evidence suggests that the size of the uterine scar and the residual myometrial thickness (RMT) are associated directly with the risk of uterine rupture and risk of dehiscence in subsequent deliveries. Impact of the prelabour and labour Cesarean section on the RMT has not been studied in detail. Objectives: To compare RMT, Caesarean scar defects and to evaluate the elasticity of the Caesarean scar between women who underwent prelabour and labour Caesarean sections. Methods: This was a Cross sectional analytical study. Women who underwent Caesarean section in their first pregnancy were recruited. Sample was stratified to prelabour and labour Caesarean section groups. Transvaginal ultrasound scan was performed six months following the Caesarean section. Dimensions of the uterus, uterine scar defect, RMT and elastosonography of the uterine scar were assessed. Results: A total of 240 postpartum women were analyzed. Uterine niche was detectable in 194 subjects. Prelabour CS group had demonstrated 91.7% (n = 110) scar defects (uterine niche) out of 120 cases and the rate among labour CS group was 70% (n = 84). There was a significant difference in the presence of uterine niche among 2 groups as Prelabour group was found to have more scar defects (p mm (SD 1.2) and 4.99 mm (SD 1.3) respectively and there was no significant difference (t = 0.38, p = 0.71). There was no significant difference between the dimensions of the uterine CS defects of the studied groups. Prelabour CS group had significantly higher Target strain [0.28 vs. 0.24 (t = 2.12, p = 0.04)] and significantly less strain ratio [1.45 vs. 1.55 (t -2.42, p = 0.04)] than labour CS group indicating a better scar in prelabour group. Conclusion: There was no significant difference in RMT and uterine scar defects between prelabour and labour Caesarean section groups. But prelabour Caesarean section scars were less stiff than labour Caesarean section scars. Further studies are warranted to elaborate on the association.

New US device versus imaging US to assess tumor-in-brain

Background:Applying ultrasonic imaging system during surgery requires the poring of saline,performing the measurement,and acquiring data from its display—which requires time and is highly“performer dependent,”i.e.,the measure is of a subjective nature.A new ultrasonic device was recently developed that overcomes most of these drawbacks and was successfully applied during tumor-in-brain neurosurgeries.The purpose of this study was to compare the two types of US devices and demonstrate their properties.Methods:The study was performed in the following stages:(i)an ex vivo experiment,where slices of the muscle and brain of a young porcine were laid one on top the other.Thicknesses and border depths were measured and compared,using the two types of US instruments.(ii)During human clinical neurosurgeries,tumor depth was compared by measuring it with both devices.(iii)Following the success of stages(i)and(ii),using solely the new US device,the tumor thickness was monitored while its resection.Correlation,Pearson’s coefficient,average,mean,and standard deviation were applied for statistical tests.Results:A high correlation was obtained for the distances of tissue borders and for their respective thicknesses.Applying these ultrasonic devices during neurosurgeries,tumor depths were monitored with high similarity(87%),which was also obtained by Pearson’s correlation coefficient(0.44).The new US device,thanks to its small footprint,its remote measurement,and the capability of monitoring intraoperatively and in real-time,provides the approach to tumor’s border before its complete resection.Conclusions:The new US device provides better accuracy than an ultrasonic imaging system;its data is objective;it enables to control the residual tumor thickness during its resection,and it is especially useful in restricted areas.These features were found of great help during a tumor-in-brain surgery and especially in the final stages of tumor’s resection.