The Wetting of Surface-Treated Silicone Impression Materials by Gypsum Mixes Containing Disinfectants and Modifiers

PURPOSE: This work evaluated wettability of silicone impression surfaces by gypsum mixes containing disinfectants. MATERIALS AND METHODS: Two types of dental stone were modified by mixing with aqueous solutions of either sodium hypochlorite or povidone iodine. These materials were subjected to further modification by adding a mixture of 1% gum arabic and 0.132% calcium hydroxide to reduce the water requirement of the hemihydrate. Mix consistency tests were carried out to determine the effect of the disinfectants and the modifying additives on the mix fluidity. Contact angles of the mixed materials were measured when they were poured against a polyvinylsiloxane impression material that had undergone the following treatments (1) no treatment (control), (2) surfactant treated, (3) disinfectant treated, and (4) treated with both surfactant and disinfectant. One-way analysis of variance (ANOVA) was carried out using Dunnett's method to determine if experimental groups were significantly different from the control. RESULTS: Gypsum mix consistency was reduced by the presence of combined gum arabic and calcium hydroxide additives. Contact angle data showed that the additives and disinfectants incorporated into the gypsum had, in general, no beneficial effect on the wetting of an untreated silicone surface, or a surface treated with surfactant. In some instances, better wetting was obtained with disinfectant-treated surfaces, and surfaces that had been disinfected and treated with surfactant. CONCLUSIONS: Fluidity of the mixed gypsum was affected by the modifying additives. Chemical disinfectants incorporated in gypsum have little effect on the wetting behavior of dental gypsum. Modifying dental stone powders with gum arabic and calcium hydroxide additives (before mixing at the manufacturers' recommended liquid/powder ratios), improved the wetting behavior of the mixed materials in some cases, but results were not consistent.     

Structural and functional aspects of porcine placental microvasculature

Summary The microvascular architecture of the pig placenta was studied by serial semithin histological sections for light microscopy, which were compared with scanning electron microscopy of artificially exposed materno-fetal contact surfaces as well as of vessel casts prepared from the maternal, fetal, and combined maternal and fetal sides.The superficial reliefs from the exposed surfaces as well as from the casts are almost identical with the complementary maternal and fetal sides. In order to meet the physiological needs of materno-fetal exchange for the rapidly growing fetuses, these reliefs develop from a simple to a more complex system during pregnancy and can be described as follows: (1) The degree of interlocking increases between the fetal ridges or bulbous protrusions and maternal ridges of different orders separated by maternal troughs of variable depth, most clearly seen on vessel casts. It creates a three-dimensional nontact area. (2) The structure of precapillary vessels as well as of the meshwork, and the diameter of capillaries of the maternal and fetal sides, adapt during gestation giving a good distribution of oxygenated blood into the maternal capillaries; these, with the development of large prevenous connecting capillaries on the fetal side, favour a high arterio-venous difference of fetal blood O₂ pressure. (3) The vascular architecture of endometrial and fetal ridges and troughs develop into a crosscurrent to countercurrent materno-fetal blood interrelationship.Our demonstration of the materno-fetal capillary interrelationship in the porcine placenta thus shows that the latter is a much more efficient organ for exchange than hitherto assumed.     

Scanning electron microscopy of esophageal microvasculature in human infants and rabbits

Summary The microvasculature of the esophagus was studied by scanning electron microscopy of vascular corrosion casts in human infants and rabbits. In both species, segmental circumferential arteries arise from main longitudinal arteries, the latter giving off numerous perforating arteries. The tunica muscularis is supplied by branches of circumferential and perforating arteries, the submucosa and its glands by branches of perforatings. Terminal arborizations of perforating arteries feed a subepithelial capillary network. These capillaries are drained by a venous plexus in the lamina propria which is connected to a submucosal venous plexus. Perforating veins, running parallel to the corresponding arteries, connect the submucosal plexus with circumferential veins, and finally empty into main longitudinal veins. Valves were not present in any of the veins. Submucosal veins were less numerous in man than in rabbit. The number and caliber of equivalent vessels in human submucosal plexus decreased from the pharyngoesophageal to the gastroesophageal junction, suggesting the latter to be at particular risk in portal hypertension. The subepithelial capillary network reveals a longitudinal arrangement in rabbits, while the same network shows no preferential organization in human infants. The microvascular architecture of the esophagus in humans and rabbits is comparable, especially in the lay-out of the venous plexuses and the absence of venous valves. Therefore the rabbit could serve as an experimental model for studies on portal hypertension. The present results strongly suggest particular significance of the venous plexus in the lamina propria for the genesis of esophageal varices.     

Venous drainage through the internal auditory meatus of the guinea pig cochlea

Summary The angioarchitecture of the guinea pig cochlea has been investigated closely using light microscopy and resin injections. However, detailed information concerning the vasculature of the modiolus is still unavailable, and even the existence of venous drainage through the internal auditory meatus is not agreed upon. In the present investigation, vascular casts of guinea pig temporal bones were studied using scanning electron microscopy. A vessel, formed by the confluence of the vascular network on the modiolar wall and having a spiral course into the internal auditory meatus was found in the modiolus of the basal turn. The vessel had a venous pattern on its cast surface and, after exiting from the internal auditory meatus, drained finally into the dural sinus. These scanning electron microscopic findings were confirmable by serial sections of the dural veins in the internal auditory meatus and the modiolus. The vessel found may correspond to the so-called internal auditory vein, but it would be more appropriate to call it the vein of the internal auditory meatus, since it appears to be an independent route of venous drainage from the modiolus.     

先天性膝关节脱位的石膏矫形治疗

目的研究先天性膝关节脱位的治疗方法,对石膏矫形治疗的可行性及指征进行探讨。方法对2006-2009年就诊的患者采用系列石膏矫形的方法进行复位治疗,共8例11膝,年龄1-25个月,其中完全脱位10例,半脱位1例,合并畸形6例。1-2周更换1次石膏,逐渐增加膝关节屈曲度,达到复位者以支具维持至膝关节稳定。结果经平均5次石膏矫形后,成功复位9膝,失败2膝。失败者就诊时年龄为20个月,合并多发关节挛缩症,且患儿对石膏耐受性差。结论对2岁以下患者,可试行采用系列石膏结合支具固定的方式来恢复关节对位,可有效减少手术带来的创伤打击;而对于4个月以内的患儿,无论是否合并畸形,均应尝试保守治疗。     

Assessment of the amount of tooth wear on dental casts and intra‐oral photographs

Tooth wear is a multifactorial condition, leading to the loss of dental hard tissues. Many grading scales are available to assess the amount of tooth wear, one of which is the tooth wear evaluation system (TWES). A grading scale can be used chairside, on casts and on photographs. The aim was to test whether the grading scales of the TWES, used on casts and on photographs, resulted in comparable scores. In addition, it was tested whether these scales can be used to assess tooth wear reliably on photographs. Of 75 tooth wear patients, sets of casts and series of photographs were obtained and graded. Comparison of the grading on casts and on photographs revealed equal median values and percentiles for both occlusal/incisal grading and non‐occlusal/non‐incisal grading. The grading on casts and on photographs showed a high correlation for the occlusal/incisal grading and a low correlation for the non‐occlusal/non‐incisal grading (Spearman's rho = 0·74 and rho = 0·47; P < 0·001). Concerning the grading on photographs, the interexaminer reliability was fair‐to‐good (ICC = 0·41 to ICC = 0·55) while the intra‐examiner reliability was fair‐to‐good to excellent (ICC = 0·68 to ICC = 0·86) for the occlusal/incisal grading. For the non‐occlusal/non‐incisal grading, the interexaminer reliability was poor to fair‐to‐good (ICC = 0·22 to ICC = 0·59), while the intra‐examiner reliability was fair‐to‐good to excellent (ICC = 0·64 to ICC = 0·82). It was concluded that the scores obtained with the grading scales of the TWES on casts and on photographs are comparable. The grading scales can be used in a reliable way on photographs, which is especially the case for occlusal/incisal grading.     

恩施土家族苗族自治州各民族正常Bolton指数的测定和分析

目的：建立恩施土家族苗族自治州（以下简称恩施州）各民族Bolton指数正常参考值标准,为本州错畸形患者的诊断、设计和预后分析提供客观科学的参考数据。方法：选择恩施州汉族、土家族和苗族接近理想正常标准模型各80副,男、女各40副,测量各样本的牙冠宽度。计算每个样本的Bolton指数,然后运用SPSS软件处理数据并进行统计学分析。结果：统计学分析表明,恩施州各民族间Bolton指数差异无显著性,男女间Bolton指数差异无显著性,民族和性别不存在交互效应。恩施州人群合并计算后Bolton指数为：前牙比为（79.82±1.76）%,后牙比为（104.38±1.93）%,全牙比为（92.59±2.12）%。结论：恩施州Bolton指数可用统一标准。与其他地区和民族公布的Bolton指数相比,存在一定差异。     

Reproducibility of the index of orthognathic functional treatment need scores derived from plaster study casts and their three-dimensional digital equivalents: a pilot study

Objective: To determine the reproducibility of Index of Orthognathic Functional Treatment Need (IOFTN) scores derived from plaster casts and their three-dimensional (3D) digital equivalents.

Design: Pilot study, prospective analytical.

Setting: UK hospital orthodontic department.

Participants: Thirty casts and their digital equivalents, representing the pre-treatment malocclusions of patients requiring orthodontic-orthognathic surgical treatment, were scored by four clinicians using IOFTN.

Methods: Casts were scanned using a 3Shape digital scanner and 3D models produced using OrthoAnalyzer^TM (3Shape Ltd, Copenhagen, Denmark). Examiners independently determined the IOFTN scores for the casts and digital models, to test their inter- and intra-operator reliability using weighted Kappa scores.

Results: Intra-operator agreement with IOFTN major categories (1–5: treatment need) was very good for plaster casts (0.83–0.98) and good-very good for digital models (0.78–0.83). Inter-operator agreement was moderate-very good for casts (0.58–0.82) and good-very good for digital models (0.65–0.92). Intra-operator agreement with IOFTN sub-categories (1–14: feature of malocclusion) was good-very good for casts (0.70–0.97) and digital models (0.80–0.94). Inter-operator agreement was moderate-good for casts (0.53–0.77); and moderate-very good for the digital models (0.58–0.90).

Conclusions: Digital models are an acceptable alternative to plaster casts for examining the malocclusion of patients requiring combined orthodontic-orthognathic surgical treatment and determining treatment need.     

Accuracy of implant casts generated with splinted and non-splinted impression techniques for edentulous patients: an optical scanning study

Background: The accuracy of implant casts generated with various impression techniques was mainly investigated in vitro resulting in limited clinical data. Purpose: (1) To compare the three‐dimensional (3‐D) accuracy of splinted and non‐splinted impression techniques to the control casts (verification jigs) that had been used for actual patient treatment; and (2) to determine the maximum level of clinically undetectable misfit. The null hypothesis was that there would be no significant difference in the accuracy of casts generated with different impression techniques. Materials and methods: The implant casts used for the prosthetic rehabilitation of 12 edentulous jaws with CAD/CAM zirconia, implant‐fixed complete dental prosthesis (IFCDP) were included in this study. Intraoral acrylic jigs were used to fabricate index casts. Splinted and non‐splinted, open‐tray techniques were used to generate two casts. Optical scanning acquisition of the x‐coordinates, y‐coordinates and z‐coordinates of the implant positions for each individual cast was performed. The “best fit” algorithm was used with computer software to superimpose the scanning datasets. Group I (n=12) included casts from the splinted impression technique vs. acrylic jig casts, and group II (n=12) included casts from non‐splinted technique vs. jig casts. Results: The paired t‐test and Wilcoxon's signed ranks test were used to compare the 3‐D discrepancies within and between groups I (splinted vs. jig) and II (non‐splinted vs. jig), respectively. Significant difference was found at the x‐axis, y‐axis and 3‐D between groups I and II (P<0.05), but not in the vertical z‐axis (P>0.05). Within subject, global 3‐D discrepancies between groups I and II were significantly different (P<0.05), corroborated by in vivo observations of clinical fit. Implant position in the arch affected the 3‐D accuracy of casts for both anterior and posterior implants (P<0.05). Conclusion: The splinted technique generated more accurate master casts than the non‐splinted technique for one‐piece IFCDPs in edentulous jaws and the null hypothesis was rejected. These clinical implications demonstrate improved accuracy of splinted impression techniques compared with the non‐splinted technique. For the external connection, the implant system used in this study, a 3‐D misfit ranging from 59 to 72 μm, may be considered the maximum discrepancy resulting in an acceptable clinical fit with one‐piece IFCDPs.