下中切牙唇舌向角度与下颌牙槽骨骨皮质及骨板厚度的相关性研究

目的：通过锥形束CT(Cone beam computed tomography,CBCT)测量不同唇、舌向倾斜度的下颌中切牙周围牙槽骨骨皮质及骨板厚度，分析下中切牙角度与该区牙槽骨形态的相关性。方法：收集2019年1月至12月就诊于首都医科大学附属北京友谊医院口腔科的成人正畸患者150例，拍摄采集其下颌中切牙区CBCT影像，以下切牙-下颌平面的角度（IMPA）为依据，分为下切牙舌倾组（IMPA<87.7°）、下切牙正常组（87.7°≤IMPA≤100.1°）和下切牙唇倾组（IMPA>100.1°），分别测量各组釉牙骨质界下2 mm处、根中1/2处和根尖处牙槽骨骨皮质及骨板厚度，并对各组间及各测量平面间进行比较。结果：从釉牙骨质界下2 mm处至根尖，各组下中切牙区唇、舌侧骨皮质厚度和牙槽骨骨板总厚度（唇侧牙槽骨骨板厚度+舌侧牙槽骨板厚度）均呈递增趋势。骨皮质最薄区位于舌倾组釉牙骨质界下2 mm处的舌侧（0.29±0.31）mm，最厚区位于正常组根尖处的舌侧（1.81±0.48）mm。牙槽骨骨板总厚度在釉牙骨质界下2 mm处和根尖处均为正常组>唇倾组>舌倾组。釉牙...     

下颌中切牙转动中心的三维有限元分析

目的:探讨下颌中切牙唇侧和舌侧的力偶距与力的比例(M/F)与牙齿转动中心(Co)的关系,并比较二者的差异.方法:创建下颌骨及下切牙的三位有限模型,从牙齿唇侧、舌侧是假不同在和求解.结果:产生牙齿整体移动时,唇侧和舌侧所需的M/F值不同,唇侧为-9.31,舌侧为-12.78.结论:舌侧正畸中,内收切牙的同时一定要加足根舌向转矩,而且不能根据唇侧加力的经验来判断.在唇侧或舌侧,不同的M/F加载下,下中切牙的转动中心位于牙长轴上,M/F值和Co位置呈双曲线关系.     

隐形矫治对成人中度慢性牙周炎患者牙周指标及唇侧外观的影响

目的:探究无托槽隐形矫治对成人中度牙周炎患者牙周指标及唇侧外观的影响。方法:选取2017年6月-2017年11月笔者医院收治的91例中度牙周炎继发错牙合畸形患者为研究对象,均采用无托槽隐形矫治进行正畸治疗,比较治疗前后上颌中切牙牙根长度、牙槽骨高度及密度、唇侧功能和美观评分。结果:治疗后牙根长度(12.07±2.11)mm,较治疗前(12.84±2.15)mm降低(P0.05),治疗前后牙根变化差值为(0.77±2.11)mm,吸收率为6.0%;治疗后唇侧、舌侧、远中位点及平均牙槽骨高度较治疗前无显著性变化(P0.05),近中位点牙槽骨高度较治疗前升高,差异具有统计学意义(P0.05);治疗后,腭侧牙槽嵴顶处(A1)、解剖根尖点冠方1mm处(A3)骨密度较治疗前均降低,差异具有统计学意义(P0.05),根中部位于根颈部和根尖中点处(A2)治疗前后无明显变化(P0.05);治疗后,患者牙齿排列、后牙咬合、前牙覆盖评分较治疗前降低,差异具有统计学意义(P0.05)。结论:无托槽隐形矫治能有效缓解中度牙周炎患者的牙根吸收、保留牙槽骨高度和骨密度,可获得较好的唇侧外观效果。     

不同形态牙本质肩领与牙根抗力的实验研究

目的:研究5种不同形态牙本质肩领对牙根抗力的影响。方法:25颗完整离体上颌中切牙随机分成5组,按实验设计制备5种不同形态牙本质肩领:即360°环形肩领组、180°唇侧肩领组、180°腭侧肩领组、180°远中肩领组和无肩领组。所有离体牙均采用预成石英纤维桩、复合树脂核、镍铬合金全冠修复。试件于铸造全冠颈缘线下2mm包埋在自凝塑料中,电子万能试验机以与牙长轴成130°,加载速度为1.0mm/min,于样本牙腭面切端下2mm处加载,记录折裂载荷及牙体断裂的位置和方式,进行统计学分析。结果:5组样本牙抗折力值顺序为环形肩领组、腭侧肩领组远中肩领组唇侧肩领组无肩领组,前两组样本牙根抗折力显著高于后两组,差异有显著性(P0.01)。所有样本中可修复性折裂占92%。结论:残根龈上剩余牙本质的位置能影响桩核冠修复后的牙根抗力。     

全口种植烤瓷牙患者牙槽骨高度和吸收状况的CBCT检测分析

目的:CBCT检测分析全口种植烤瓷牙患者牙槽骨高度和吸收状况,为临床治疗提供参考依据。方法:选择2016年2月-2019年4月采用随机奇偶数字的方法抽取承德市某三甲医院收治的100例全口种植烤瓷牙患者,采用χ~2检验比较上下磨牙牙槽骨吸收类型,采用t检验比较上下磨牙牙槽骨吸收程度及治疗前后牙槽骨高度变化。结果:上、下磨牙牙槽骨吸收类型中,垂直型吸收少于水平型吸收(P0.05);下颌磨牙牙槽骨总位点的水平型吸收多于上颌磨牙(P0.05);上侧磨牙在DB、DP、D位点牙槽吸收水平低于下侧磨牙(P0.05);上侧磨牙在M位点牙槽吸收水平高于下侧磨牙(P0.05);治疗后近中、远中、唇侧、舌侧牙槽骨高度均高于治疗前,差异均有统计学意义(P0.01)。结论:相比种植烤瓷牙修复前,全口种植烤瓷牙患者牙槽骨高度变化较大,全口种植烤瓷牙有利于促进牙槽骨改建,提高治疗效果。     

转矩力作用下上颌切牙段应力分布的三维有限元分析

目的:研究上颌切牙段在10N·mm冠唇向、根舌向力偶作用下,牙齿及其牙周支持组织应力分布及移动趋势。方法:三维有限元分析方法。所采用模型为包括牙齿、牙周膜、牙槽骨、托槽、弓丝的左侧上颌切牙段的有限元模型[1]。模型所加转矩力为10N·mm冠唇向、根舌向力偶。结果:①上颌切牙段在转矩力作用下,中、侧切牙应力分布基本相同,牙根表面最大,齿槽骨次之,牙周膜最小。②上颌切牙段在转矩力作用下,主要产生冠唇向、根舌向的倾斜移动,同时伴有垂直向和近远中向移动趋势。结论:该结果为临床上合理使用转矩提供了力学参考。     

种植体支抗结合片段弓矫治成人下颌牙列拥挤的临床应用研究

目的:研究安氏I类错牙合患者中,采用种植体支抗结合片段弓技术,矫治成人下颌牙列拥挤的临床效果及其作用特点。方法:选择12例成人患者,将24枚微型种植体植于下颌第一磨牙与下颌第二前磨牙之间的颊侧牙槽骨内,Ni-Ti螺旋弹簧拉长后分别连接于种植体与下颌侧切牙远中的牵引钩,来内收下前牙关闭间隙。测量下颌中切牙的颊舌向的位置变化、压低量、近远中倾斜度以及移动的速度,并通过治疗前后的X线片对比以观察切牙牙根有无吸收,牙周膜腔的变化情况。通过测量下颌第一磨牙的位置变化来衡量支抗强弱。结果:下颌中切牙向舌侧移动1.6mm,舌侧倾斜4.5°,平均压低0.5mm,无近远中倾斜,疗程3.2个月,平均向舌侧移动速度0.67mm/月;切牙牙根没有吸收,牙周膜腔宽度没有改变。下颌第一磨牙的位置没有改变。结论:所有下颌牙列的拥挤得到了解除,下颌磨牙位置没有改变,后牙咬合关系无变化。     

应用CBCT评估“根膜种植牙”术后唇侧骨量变化

目的:评估美学区单颗牙"根膜种植技术"与I型即刻种植术后6个月唇侧牙槽骨尺寸变化。方法:根据纳入排除标准共选入30例患者,采用随机数表法分为实验组行"根膜种植牙技术"(n=15)和对照组行传统不翻瓣即刻种植型即刻种植(n=15),利用锥形束CT(Cone beam computed tomography,CBCT)评估分析两组美学区单牙种植术后6个月种植牙唇侧牙槽骨板尺寸的变化。结果:术后6个月两项指标平均值分别:实验组厚度(1.15±0.27)mm ,对照组厚度(0.83±0.13)mm;实验组高度(2.59±0.21)mm ,对照组高度(1.82±0.18)mm,术后6个月单牙唇侧牙槽骨高度和厚度两组平均尺寸变化比较,均有统计学差异(P0.05)。结论:采用"根膜种植牙技术"一定程度上减少了在自然愈合中发生的颊侧骨板的吸收,对美学区单颗牙唇侧骨板有相对理想的保存效果。     

舌侧活动翼矫治器治疗双颌前突的临床研究

目的:研究舌侧活动翼矫治技术治疗均角型双颌前突的临床疗效。方法:选取均角型双颌前突患者31例(29°相似文献   

人字曲作用下上颌切牙段应力分布的三维有限元分析

目的研究上颌切牙段在方丝弓"T"形曲近远中各加15°"人"字曲的情况下牙齿及牙周支持组织应力分布及移动趋势。方法三维有限元分析方法,所采用的模型为包括牙齿、牙周膜、牙槽骨、托槽、弓丝在内的左侧上颌切牙段有限元模型[1]。模型上模拟"T"形曲近远中各加15°"人"字曲的情况进行加载。结果在"人"字曲加力的瞬间,侧切牙与中切牙相比更趋近于可控性的倾斜移动;无论是位移和应力水平侧切牙均显著高于中切牙。结论"人"字曲的使用,可以更好地控制间隙两侧牙齿的移动。     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

Immunomodulation in Transplantation with Photopheresis

Abstract: Photopheresis is a technique in which peripheral blood mononuclear cells, in the presence of a photoacti-vatable compound, are exposed extracorporeally to ultraviolet A light and reinfused, inducing a host autoregula-tory immune response. Experimental work and ongoing clinical studies are helping to define the role of this novel, safe, and non-toxic immunomodulating technology in the field of transplantation.