Treatment of frictional dental hypersensitivity (FDH) with computer-guided occlusal adjustments

Objective: To verify the efficacy of treating dentin/dental hypersensitivity (DH) to Cold Ice Water Swish testing before and after subjects undergo the Immediate Complete Anterior Guidance Development (ICAGD) computer-guided occlusal adjustment.

Methods: One hundred chronically dysfunctional patients with known cold sensitivity swished ice water intraorally to elicit a DH response scored on a Visual Analog Scale (VAS). The subjects then underwent the ICAGD coronoplasty, which was followed by a second ice water swish scored with a second VAS. The pre to post ICAGD Disclusion Time values and VAS scores were statistically evaluated by the Wilcoxon Signed Rank for Paired Difference test. The subjects were divided into subgroups with DH sensitivities <4 and ≥4, and analyzed. Limitations were as follows: abfractions were not quantified, dysfunctional symptom resolution was not determined, each subject was their own control, one clinician administered all ice water tests, and protrusive excursions were not included.

Results: Disclusion Time reductions from ICAGD were significant (2.11–0.55 s. p = 0.0000). The DH score changes showed highly significant decreases from pre to post ICAGD (p < 0.0001).

Conclusions: A partial etiology for cold tooth sensitivity exists, resultant from prolonged occlusal surface excursive movement frictional contacts. This cold sensitivity can be lessened with measured, computer-guided occlusal adjustments.     

Producing desired ice faces

The ability to prepare single-crystal faces has become central to developing and testing models for chemistry at interfaces, spectacularly demonstrated by heterogeneous catalysis and nanoscience. This ability has been hampered for hexagonal ice, I_h––a fundamental hydrogen-bonded surface––due to two characteristics of ice: ice does not readily cleave along a crystal lattice plane and properties of ice grown on a substrate can differ significantly from those of neat ice. This work describes laboratory-based methods both to determine the I_h crystal lattice orientation relative to a surface and to use that orientation to prepare any desired face. The work builds on previous results attaining nearly 100% yield of high-quality, single-crystal boules. With these methods, researchers can prepare authentic, single-crystal ice surfaces for numerous studies including uptake measurements, surface reactivity, and catalytic activity of this ubiquitous, fundamental solid.Studies of model, single-crystal surfaces have revolutionized understanding of a vast array of heterogeneous catalysts and nanoparticles ranging from pure metals to alloys to semiconductors. Applying the single-crystal surface strategy to ice––arguably one of the most fundamental and ubiquitous hydrogen-bonded interfaces––has been limited due to challenges associated with surface generation. As a result, questions about molecular-level dynamics, surface binding site patterns, and the molecular-level structure remain unanswered (1). Several strategies have been adopted for studying ice: (i) Depositing solid water on a metal or ionic substrate that matches the oxygen lattice (2, 3). However, ice on a substrate often has distinctly different properties from those of neat ice; indeed, such ice can even be hydrophobic (4, 5)! (ii) Uptake measurements often use a Knudsen cell with vapor-deposited ice on a substrate (6) or compacted, finely divided, artificial snow (7) to arrive at a molecular-level picture for gas–particle interaction despite the irregular, highly variable surfaces used. (iii) Small crystallites can be well characterized but, as highlighted by Libbrecht and Rickerby (8), results can be clouded by competition from nearby crystallites; small faces compete with adjacent faces. In addition, crystallites are perturbed by the supporting surface. It is therefore desirable to prepare macroscopic samples with known faces.Interactions at ice surfaces have a particularly profound effect on climate. For example, correlational studies suggest that rain formation depends on ice particles in clouds (9), but not all ice-containing clouds yield rain. It is thought that variation in supersaturation and the mechanism for gathering water molecules by ice particles profoundly affects precipitation. Discrepancies between experiment and theory are often rationalized as a result of irregular shapes, inelastic scattering, or differing binding sites leaving large uncertainties for climate models (10). More reproducible, well-characterized surfaces of I_h––the most stable form of ice at ambient pressure––are needed to bring clarity.Ice is unusual in that the macroscopic sample does not reveal the crystal lattice orientation. Neighboring grain lattice orientation is a critical issue in the ice-core and glaciology communities (11). Hence, previous work (12–14) focused on determining grain orientation with respect to the grain boundary. The most quantitative of these are the two methods of Matsuda (12). The first uses etch pits measuring lengths inside the pit. Large uncertainties in length measurements result in large uncertainties in lattice axis orientation angles; this is not a major issue for grain growth studies but is a serious problem for generating targeted faces. The second method measures only the azimuths, thus incompletely determining orientation. Both methods break down if the optic axis is near-parallel to the surface, and neither provides the tools required to accurately orient a macroscopic sample to generate a targeted face. Lattice orientation could be determined with X-ray methods (15, 16) provided such determination includes a connection to the macroscopic sample. For wide-spread use, a laboratory-based method is preferable. This work describes two methods to fill this important need. The first uses pit perimeter ratio measurements; because the perimeter is sharp, accuracy is greatly improved. The second method locates the optic axis via cross-polarizers (11, 17), then precisely determines the hexagonal orientation via etching. Closed-form, analytical formulas are derived relating lattice orientation to the macroscopic sample. These orientation formulas feed into rotation matrices generating additional analytical formulas enabling precise cutting of any targeted face. The result is illustrated by cutting each of the three major ice faces. These techniques provide researchers with the tools needed to prepare neat ice surfaces.This work specifically describes face preparation from cylindrical boules (18); however, the method is easily adapted to any macroscopic, single-crystal geometry. Due to nearly equal energy faces, ice takes on the shape of the confining container. The near-energy match is demonstrated by growth in the modified Bridgeman apparatus (19). Nucleation occurs on a polycrystalline seed; single-crystal growth is achieved due to competitive growth among the multiple ice–water interfaces (18). Careful thermal management maintains near-equilibrium conditions yielding a large single crystal, but the crystal orientation is not a priori known. [Note: ice seeded by a floating crystal tends to have the optic axis perpendicular to the growth direction but single-crystal yield is low, ~10% (20).] Close energy match among the faces also means that ice does not readily cleave along any lattice plane (21). Thus, successful face preparation for any ice sample begins with characterization of the lattice orientation.     

自制简易盐袋、冰块固定装置在膝关节置换术后应用简

人工全膝关节置换术的应用极大改善了患者生活质量,对于骨性关节炎、类风湿性关节炎等患者现已成为一种重要的治疗手段;但术后大量渗血,增加了围手术期风险,影响其预后。国内学者应用石膏托固定、冰敷、弹力绷带等综合措施,在减少术后出血方面取得了一定疗效。在临床使用冰敷过程中由于多种原因致冰块移位,达不到有效的冰敷止血。为此,我科自制简易盐袋、冰块固定装置在全膝关节置换术后应用起到良好效果。     

Rapid reductions and millennial-scale variability in Nordic Seas sea ice cover during abrupt glacial climate changes

Constraining the past sea ice variability in the Nordic Seas is critical for a comprehensive understanding of the abrupt Dansgaard-Oeschger (D-O) climate changes during the last glacial. Here we present unprecedentedly detailed sea ice proxy evidence from two Norwegian Sea sediment cores and an East Greenland ice core to resolve and constrain sea ice variations during four D-O events between 32 and 41 ka. Our independent sea ice records consistently reveal a millennial-scale variability and threshold response between an extensive seasonal sea ice cover in the Nordic Seas during cold stadials and reduced seasonal sea ice conditions during warmer interstadials. They document substantial and rapid sea ice reductions that may have happened within 250 y or less, concomitant with reinvigoration of deep convection in the Nordic Seas and the abrupt warming transitions in Greenland. Our empirical evidence thus underpins the cardinal role of rapid sea ice decline and related feedbacks to trigger abrupt and large-amplitude climate change of the glacial D-O events.

Sea ice is a critical component of the global climate system as it affects Earth’s albedo, phytoplankton productivity, ocean-atmosphere heat and gas exchange, and ocean circulation (1). Rapid sea ice retreat, as observed in the modern Arctic Ocean, exerts important climate feedbacks that may lead to an accelerated climate warming at northern high latitudes (2). While many climate models have difficulties in reproducing the currently observed Arctic sea ice decline (3), the rates of ongoing atmospheric warming in some Arctic regions are already comparable with those of prominent abrupt climate changes that occurred during the last glacial period (4). The latter are referred to as Dansgaard–Oeschger (D-O) climate events and known from Greenland ice core records as abrupt shifts between cold Greenland stadials (GS) and warmer Greenland interstadials (GI) occurring repeatedly ∼10–110 ka (5, 6). The millennial-scale glacial climate variability was a global phenomenon with different characteristics in the northern and southern hemispheres, but the most striking feature of the D-O events is an extremely abrupt climate transition that includes an atmospheric warming of 5–16.5 °C over the Greenland ice sheet happening in just a few decades (7). Analogous to the modern and future sea ice retreat and resulting warming in the Arctic, the abrupt D-O climate transitions are widely believed to have been amplified by rapid sea ice retreat in the Nordic Seas (8–15).Today, the Nordic Seas are largely ice-free, and warm Atlantic surface waters flow into the Norwegian Sea as far north as Svalbard at ∼80°N (Fig. 1), where the Arctic sea ice cover is being eroded, in particular in the Barents Sea. The warm Atlantic surface waters release heat to the atmosphere as it flows northward, which is accompanied by convective intermediate and deep-water formation between Norway and Greenland, feeding the lower limb of the Atlantic Meridional Overturning Circulation (AMOC) (16). A portion of the Atlantic waters continues flowing into the stratified Arctic Ocean as subsurface waters (17). While the pattern of ocean circulation during GI was fairly comparable to that today, proxy data indicate that the glacial Nordic Seas exhibited a stable surface stratification during GS, similar to the modern Arctic Ocean (13, 18). The AMOC and associated northward surface heat transport into the Nordic Seas were weakened during GS, with most extreme weakening related to Heinrich events signified by massive iceberg discharges to the North Atlantic (19, 20). Intermediate and deep waters in the stadial Nordic Seas were 2–4 °C warmer as compared with GI or modern conditions, resulting from a stable halocline and reduced open-ocean convection (21, 22). Contemporaneously, an extended sea ice cover reaching at least as far south as the Greenland–Scotland Ridge at ∼60°N insulated the high-latitude atmosphere from the deep oceanic heat reservoir (23, 24). Model simulations support a subsurface warming scenario under extended sea ice during GS (22, 25, 26) and suggest that a rapid removal of the sea ice cover might have caused the abrupt and high-amplitude D-O climate warming (11, 12, 14, 15).Open in a separate windowFig. 1.Core sites and regional context of the study area. Yellow diamonds mark the core sites investigated in this study. The map shows the core-top P_BIP₂₅ distribution (42, 43, 63), illustrating the great potential of the biomarker approach for sea ice reconstruction. Orange, yellow, and green dots mark core-top sites north, east, and south of Greenland, respectively, data of which are investigated in this study. Small black dots indicate locations of published core-top data. Purple lines mark the modern sea ice extent during September (dashed) and March (solid), averaged between A.D. 1981 and 2010 (https://nsidc.org/; ref. 64). The thin blue line shows the P_BIP₂₅ = 0.2 isoline, representing best the modern winter/spring sea ice extent. Red arrows illustrate the warm and saline North Atlantic Current (NAC). The map was produced with Ocean Data View software (65).Although there is some evidence of millennial-scale sea ice fluctuations during the last glacial, the few available sea ice proxy records (23, 24, 27–31) are mostly restricted to the southern Norwegian Sea and the Arctic Ocean, often have a limited temporal resolution, and partly reflect opposing trends regarding stadial–interstadial sea ice changes depending on the proxies used. Here we present high-resolution sea ice biomarker records from two key sites that form a North–South transect within the Atlantic inflow region in the Norwegian Sea and are thus ideally suited to record spatiotemporal shifts in sea ice cover in both the entrance and the interior of the ocean basin, oceanic fronts, and Atlantic water inflow during the last glacial (Fig. 1). Furthermore, we combine these marine sea ice proxy records with an independent sea ice record based on bromine-enrichment (Br_enr) values from an East Greenland ice core, which significantly enhances the spatial coverage, the robustness of results, and temporal constraint of the sea ice reconstruction. We focus on five representative glacial D-O cycles between 32 and 41 ka, which comprise long- and short-lasting GI as well as several GS, one of which includes Heinrich Event 4. The application of the cryptotephra-based chronological constraints provides a level of robustness as to the timing, duration, and nature of the events unfolding during abrupt climate changes. Our study provides robust empirical evidence that resolves rapid and widespread sea ice retreat in the Nordic Seas and its role in initiating and amplifying the abrupt climate change of the glacial D-O events.     

自制可调式冰袋对髋膝关节置换术后患者疼痛及引流量的影响

目的探究髋膝关节置换术后患者应用自制可调式冰袋对其疼痛及引流量的影响。方法选取海安市中医院2018年4月至2020年4月收治的髋膝关节置换术患者126例为研究对象,按随机数字表法分为对照组和观察组各63例。对照组采用常规冰袋冰敷,观察组采用自制可调式冰袋冰敷。对比两组患者手术后关节引流量、肿胀度及疼痛情况。结果观察组患者干预1 d、2 d、3 d后,关节引流量均少于对照组,关节肿胀度和疼痛程度均轻于对照组,差异有统计学意义（均P＜0.05）。结论自制可调式冰袋应用于髋膝关节置换术后患者可有效减少其关节引流量,减轻其关节肿胀及疼痛程度,值得临床推广。     

氩氦刀冷冻消融时间与冰球大小关系的实验研究

目的研究氩氦刀冷冻时间与冰球大小的关系,为临床确定最佳冷冻时间及冷冻靶区设计提供理论依据.方法离体猪肝在37℃恒温液中接受氩氦刀冷冻,分别即时测量2、3 mm氩氦刀冷冻以及两把3 mm氩氦刀间距30 mm冷冻不同时间点时形成冰球长径与横径,进行统计分析.结果直径2 mm刀最大冰球体积分别可达(71×50×50)mm3,直径3 mm刀最大冰球体积(75×56×56)mm3;2把直径3 mm以及3把直径3 mm的氩氦刀组合冷冻时,最大冰球范围分别可达(90×80×56)mm3和(105×100×80)mm3大小.无论哪种方式冷冻,在30 min以内冰球纵径和横径增加明显(P＜0.05),30 min以后冰球体积无明显增长(P＞0.05).结论 氩氦冷冻肿瘤时,靶区消融疗效确切,一般冷冻时间选择在25～30 min较为适宜.     

Cryoultramicrotomy as a Preparative Method for X-ray Microanalysis in Pathology

The role of ion shifts in cell injury has become one of the most intriguing fields of application of X-ray microanalysis in pathology. In principle, cryo(ultra)-microtomy is the best preparative method for X-ray microanalysis of diffusible substances. In this review, the following points are discussed: the choice of freezing method and coolant, the use of high molecular weight polymer cryoprotectants and their possible physiological effects, the choice of the cryosectioning temperature, and techniques for handling and transfer of sections. Experiences with the sectioning of cryo-protected tissue are presented. Finally, other preparative techniques for microanalysis are compared to cry oul tram icrotomy.     

Ice Cream Headache - Site, Duration, and Relationship to Migraine

OBJECTIVE--To examine the characteristics of cold-induced headaches in a group of migraine patients, to compare these with their usual migraine headaches and with cold-induced headaches in a control population. DESIGN--Subjects completed a structured questionnaire recording previous headache history along with the characteristics of any headache produced during supervised palatal and pharyngeal application of ice cream. SUBJECTS--70 consecutive patients attending the City of London Migraine Clinic, and 50 pre-clinical medical and dental student volunteers from Queen Mary and Westfield College. RESULTS--27% of the migraine patients and 40% of the students reported previous ice cream headaches. 17% of the migraine patients and 46% of the students developed headache following palatal application or a swallow of ice cream. Typically the headache was of early onset (x = 12.5s) and short duration (x = 21s), with a tendency for anterior headache on the same side as a palatal stimulus, and bilateral headache following an ice cream swallow. However, a significant minority experienced a previously unreported headache of late onset (x = 102s) and long duration (x = 236s) which tended to occur particularly after swallowing ice cream and to be less well localised to the side of the cold stimulus. Ice cream appeared not to be a common trigger for migraine, and there was no significant correlation between site of ice cream headache and usual site of migraine. CONCLUSIONS--These findings confirm that cold stimulation of the palate or pharynx commonly produces a headache. In contrast to previous studies, our results suggest that the 'ice cream headache' is less common in migraine patients than the general population. A similar pattern of headache was produced in both migraine patients and controls, and apart from the few for whom an ice cream headache may trigger a migraine, the ice cream headache seems not to have any special significance for migraine patients.     

茯苓蜂皇浆对体外人胚肺二倍体成纤维细胞的抗衰老研究

以体外培养的人胚肺二倍体成纤维细胞(HELF 2BS株)为材料。当细胞培养至25代时,将细胞分为加茯苓蜂皇浆的给药组和不加茯苓蜂皇浆的对照组。2组在相同条件下传代培养,直至细胞停止增殖。结果表明:给药组细胞能生长到65代,而对照组细胞仅存活至55代。实验组细胞寿命比对照组提高18％。提示茯苓蜂皇浆对人胚肺二倍体成纤维细胞有一定的抗衰老作用。     

Alterations in cerebral potentials evoked by rectal distention and drinking ice water in patients with irritable bowel syndrome

AIM: Visceral hypersensitivity has been found to be present in irritable bowel syndrome (IBS). The current study sought to study visceral afferent hypersensitivity in IBS patients and obtain further objective evidence of alterations in intestinal afferent pathways in IBS patients by cerebral evoked potentials (CEP). METHOD: We studied 30 female IBS patients and 12 female healthy subjects. Rectal perception thresholds to balloon distention were measured and CEP was recorded in response to rhythmic rectal distention (two distention series, each of 100 repetitions at a frequency of 1 Hz) at the volume of perception thresholds. All subjects were then asked to drink 220 mL 4 degrees C ice water and the above steps were repeated 20 min later. RESULTS: Rectal distention led to recognizable and reproducible CEP. Compared to healthy subjects, IBS patients demonstrated significantly shorter N1, P1 and N2 latencies (P < 0.05). After drinking ice water, IBS patients exhibited further shortened N1, P1 and N2 latencies (P < 0.05), but drinking did not alter the latencies of healthy controls and the amplitudes of both IBS patients and healthy controls. CONCLUSION: The shorter latency of cerebral potentials evoked by rectal distention and ice water stimulation in IBS patients provided further objective evidence for defective visceral afferent transmission in IBS patients.