3D printed replicas for endodontic education.

AIM: To assess the feasibility of producing artificial teeth for endodontic training using 3D printing technology, to analyse the accuracy of the printing process, and to evaluate the teeth by students when used during training. METHODOLOGY: Sound extracted human teeth were selected, digitalized by cone beam computed tomography (CBCT) and appropriate software and finally reproduced by a stereolithographic printer. The printed teeth were scanned and compared with the original ones (trueness) and to one another (precision). Undergraduate dental students in the third and fourth years performed root canal treatment on printed molars and were subsequently asked to evaluate their experience with these compared to real teeth. RESULTS: The workflow was feasible for manufacturing 3D printed tooth replicas. The absolute deviation after printing (trueness) ranged from 50.9 to 104.3 µm. The values for precision ranged from 43.5 to 68.2 µm. Students reported great benefits in the use of the replicated teeth for training purposes. CONCLUSION: The presented workflow is feasible for any dental educational institution who has access to a CBCT unit and a stereolithographic printer. The accuracy of the printing process is suitable for the production of tooth replicas for endodontic training. Undergraduate students favoured the availability of these replicas and the fairness they ensured in training due to standardization.

Interactions between range-expanding tropical fishes and the northern Gulf of Mexico red snapper Lutjanus campechanus.

Experimental investigation of the intensity of potential competitive interactions among increasingly abundant tropically-associated grey Lutjanus griseus and lane snapper Lutjanus synagris and resident northern Gulf of Mexico (nGOM) red snapper Lutjanus campechanus was undertaken in large outdoor mesocosms. In pair-wise interaction trials, compared with L. synagris, L. campechanus demonstrated significantly increased roving behaviour and predatory activity. While no significant difference in these activities was observed between L. campechanus and L. griseus, when all three snappers (Lutjanidae) were grouped together L. campechanus swimming activity significantly decreased in the presence of both tropically-associated species. Overall, L. campechanus were more active and aggressive predators and appear to be competitively resistant to L. griseus and L. synagris. As lower latitude species have continued to become increasingly prevalent in nGOM habitats and regional warming continues to affect resident reef-associated fishes, these findings contribute to the assessment of the effects of warming-related species shifts upon nGOM fishes and document current partial resilience of L. campechanus to climate-related expansions of tropical confamilials.

Visualization of Pulpal Structures by SWIR in Endodontic Access Preparation.

Endodontic access preparation is one of the initial steps in root canal treatments and can be hindered by the obliteration of pulp canals and formation of tertiary dentin. Until now, methods for direct intraoperative visualization of the 3-dimensional anatomy of teeth have been missing. Here, we evaluate the use of shortwave infrared radiation (SWIR) for navigation during stepwise access preparation. Nine teeth (3 anteriors, 3 premolars, and 3 molars) were explanted en bloc with intact periodontium including alveolar bone and mucosa from the upper or lower jaw of human body donors. Analysis was performed at baseline as well as at preparation depths of 5 mm, 7 mm, and 9 mm, respectively. For reflection, SWIR was used at a wavelength of 1,550 nm from the occlusal direction, whereas for transillumination, SWIR was passed through each sample at the marginal gingiva from the buccal as well as oral side at a wavelength of 1,300 nm. Pulpal structures could be identified as darker areas approximately 2 mm before reaching the pulp chamber using SWIR transillumination, although they were indistinguishable under normal circumstances. Furcation areas in molars appeared with higher intensity than areas with canals. The location of pulpal structures was confirmed by superimposition of segmented micro-computed tomography (µCT) images. By radiomic analysis, significant differences between pulpal and parapulpal areas could be detected in image features. With hierarchical cluster analysis, both segments could be confirmed and associated with specific clusters. The local thickness of µCTs was calculated and correlated with SWIR transillumination images, by which a linear dependency of thickness and intensity could be demonstrated. Lastly, by in silico simulations of light propagation, dentin tubules were shown to be a crucial factor for understanding the visibility of the pulp. In conclusion, SWIR transillumination may allow direct clinical live navigation during endodontic access preparation.

Selective loss of unmyelinated nerve fibers after extracorporeal shockwave application to the musculoskeletal system.

Application of extracorporeal shockwaves (ESW) to the musculoskeletal system may induce long-term analgesia in the treatment of chronic tendinopathies of the shoulder, heel and elbow. However, the molecular and cellular mechanisms behind this phenomenon are largely unknown. Here we tested the hypothesis that long-term analgesia caused by ESW is due to selective loss of nerve fibers in peripheral nerves. To test this hypothesis in vivo, high-energy ESW were applied to the ventral side of the right distal femur of rabbits. After 6 weeks, the femoral and sciatic nerves were investigated at the light and electron microscopic level. Application of ESW resulted in a selective, substantial loss of unmyelinated nerve fibers within the femoral nerve of the treated hind limb, whereas the sciatic nerve of the treated hind limb remained unaffected. These data might indicate that alleviation of chronic pain by selective partial denervation may play an important role in the effects of clinical ESW application to the musculoskeletal system.

[Ponseti method for treatment of idiopathic clubfoot]. / Klumpfußtherapie nach Ponseti.

OBJECTIVE: Pain-free, plantigrade, functional foot through gentle manipulation without extended surgery and with decreased probability of relapse. INDICATIONS: Idiopathic clubfoot; neurogenic and secondary clubfeet. CONTRAINDICATIONS: None. SURGICAL TECHNIQUE: Simultaneous correction of all components of the clubfoot. Mainly conservative, with serial casts. Slight supination to address the cavus and increasing abduction to align the midfoot bones while putting counter-pressure on the head of the talus. Surgery primarily only to correct the equinus, which can often not be accomplished through casting, and consists of a simple subcutaneous section. Due to tendency to relapse, further surgery might be necessary, followed by serial casting. Remaining deformity can be treated by percutaneous lengthening of the Achilles tendon, percutaneous release of the plantar fascia or a transfer of the tibialis anterior tendon to the third cuneiform. POSTOPERATIVE MANAGEMENT: Abduction orthosis for stabilization of the clinical result 24 h/day for 3 months, then only at night- and naptime through end of the third year of life. Follow-up every 3-4 months.

[Modified PemberSal osteotomy technique with lyophilized human allograft]. / Technik der modifizierten PemberSal-Osteotomie mit lyophilisiertem humanem Allograft.

OBJECTIVE: PemberSal osteotomy to improve femoral head coverage by rotating the acetabular roof ventrally and laterally. INDICATIONS: Insufficient coverage of the femoral head, and can be combined with other surgical procedures such as femoral intertrochanteric varus-derotation osteotomy and open reduction for developmental dysplasia and dislocation of the hip or to improve sphericity and containment in Legg-Calvé-Perthes disease. This specific acetabuloplasty can only be performed in patients with an open epiphyseal growth-plate. CONTRAINDICATIONS: Increased bleeding tendency (e.g., inherited or iatrogenic); elevated anesthetic risk such as in cerebral palsy, arthrogryposis multiplex congenital, trisomies; syndromes require explicit interdisciplinary clarification to reduce perioperative risks; infections as in other elective surgeries; diseases/deformities making postoperative spica casting impossible or impractical (e.g., deformities of spinal cord or urogenital system, hernias requiring treatment); closed epiphyseal plate requires complex three-dimensional corrections of the acetabular roof (e.g., triple/periacetabular osteotomy). SURGICAL TECHNIQUE: Osteotomy from the iliac bone to the posterior ilioischial arm of the epiphyseal growth-plate cartilage; controlled fracture of the cancellous bone without breaking the medial cortex of the iliac bone for ventrocaudal rotation of the acetabular roof. To refill and stabilize the osteotomy site, an allogenic bone-wedge is interponated and secured by a resorbable screw or kirschner wire. This method also allows more complex reconstructions of the acetabular roof, e.g., by including the pseudo-cup in a modified Rejholec technique. POSTOPERATIVE MANAGEMENT: A spica cast is applied to immobilize the hip for 6 weeks. Afterwards physiotherapy can be performed under weight-bearing as tolerated. Radiographic check-ups every 6 months.

[Botulinum Toxin in the Musculoskeletal System]. / Botulinumtoxin am Bewegungsapparat.

Over the last 20 years, botulinum toxin has proven to be an effective agent in the orthopaedic treatment of musculoskeletal diseases. The author presents a detailed summary of the data on the use of botulinum toxin in different indications. New indications and dosages will be developed in the coming years. As some of the newer indications for botulinum toxin are off-label, its pharmacokinetics must be carefully considered and the indication must be strictly based on current study data. Physicians using this drug should attend special professional courses.

Cytoskeletal derangements of cortical neuronal processes three hours after traumatic brain injury in rats: an immunofluorescence study.

Semiquantitative Western blot analyses have shown that traumatic brain injury (TBI) can produce significant loss of cytoskeletal proteins (neurofilament 68 [NF68], neurofilament 200 [NF200] and microtubule associated protein 2 [MAP2]) possibly by calpain-mediated proteolysis. Thus, we employed immunofluorescence (light and confocal microscopy) to study the histopathological correlates of acute neurofilament and MAP2 protein decreases observed 3 hours following unilateral cortical injury in rats. TBI induced dramatic alterations in NF68, NF200, and MAP2 immunolabeling in dendrites within and beyond contusion sites ipsilateral and contralateral to the injury site. Marked changes in immunolabeling were associated with but not exclusively restricted to regions of dark shrunken neurons labeled by hematoxylin and eosin staining, a morphopathological response to injury suggesting impending cell death. Light microscopic studies of NF200 immunofluorescence revealed a prominent fragmented appearance of apical dendrites of pyramidal neurons within layers 3 and 5, as well as a loss of fine dendritic arborization within layer 1. Confocal microscopy detected varying degrees of NF200 disassembly associated with these areas of neurofilament fragmentation. Light microscopic studies of NF68 immunofluorescence detected subtle and less severe structural changes including smaller breaks and focal vacuolization of apical dendrites. Light microscopic immunofluorescence of MAP2 revealed changes similar to those seen for NF200. Acute axonal alterations detected with NF68 were minimal compared to immunofluorescence changes seen in dendritic regions. Therefore, preferential dendritic cytoskeletal derangements may be an early morphological feature of experimental traumatic brain injury in vivo. In addition, these cytoskeletal derangements may not be exclusively restricted to sites of contusion and cell death.

Phospholipids involved in specific binding of 12-O-(5-azido-2-nitrobenzoyl)phorbol-13-acetate to epidermal microsomes, a photolabeling study.

The preparation of 12-O-(5-azido-2-nitro)benzoylphorbol-13-acetate (NABPA) is described. It is used as a photoaffinity probe to study the biochemical components involved in the specific binding of phorbol esters to an epidermal particulate fraction (microsomes) from NMRI mice: without irradiation NABPA binds in a saturable and high affinity manner (KD = 12 nM; Rt = 2.6 pmol/mg protein) to microsomes; after irradiation (at 350 nm) specific photolabeling (representing specific binding of NABPA) is found of phospholipids (phosphatidyl-serine (PS) and -ethanolamine(PE)), but not of protein. The results are discussed in the context of protein kinase C being a receptor for phorbol esters.

Are very low birthweight births among American Indians and Alaska Natives underregistered?

BACKGROUND: International infant mortality rates vary widely. This variation has been attributed to many factors, including differential reporting. In the US, American Indians and Alaska Natives (AI/AN), who generally have low socioeconomic status, have a low neonatal mortality rate. One possible explanation is underregistration of very low birthweight (VLBW, < 1,500 g) births. We hypothesized that underregistration may occur disproportionately among AI/AN residing on or near reservations (areas controlled by an American Indian group). We estimated infant mortality in these areas. METHODS: Linked birth-infant death files for 1989-1991 were used to compare VLBW and neonatal mortality among AI/AN infants in counties with reservations with those in non-reservation counties. The VLBW rates for non-reservation counties were applied to the reservation risk distribution to calculate directly adjusted VLBW and neonatal mortality rates for reservation counties. This method assumes that greater registration in non-reservation counties yields a more accurate estimate of the relationship between risk factors and outcomes. RESULTS: Despite a higher prevalence in reservation counties of risk factors, the reported VLBW rate was 0.84% in reservation and 1.17% in non-reservation counties. The neonatal mortality rate was 5.4 per 1,000 in reservation counties and 6.0 in non-reservation counties. Direct adjustment yielded a VLBW rate of 1.28% (95% CI: 1.14-1.39) and a neonatal mortality rate of 6.7-9.8 per 1,000 in reservation counties. CONCLUSIONS: Reported neonatal mortality among AI/AN may understate the true rate due to underregistration of VLBW births. Direct adjustment may be useful in estimating infant mortality rates for populations with incomplete vital registration.

Hormone replacement therapy and breast cancer risk in a nationally representative cohort.

BACKGROUND: The relative risk of breast cancer associated with the use of postmenopausal hormone replacement therapy (HRT) continues to be debated. We used a nationally representative cohort to study the issue. METHODS: This analysis utilized data from the NHANES I Epidemiologic Follow-up Study. Subjects were interviewed in 1971 through 1974 and four waves of follow-up interviews were conducted through 1992. Survival analysis of 5,761 postmenopausal women provided estimates of the relative risk of breast cancer in users of HRT when compared with non-users, controlling for potential confounders. RESULTS: There were 219 incident cases of breast cancer in 73,253 person-years of follow-up. The incidence rate was 326 per 100,000 person-years in women who had never used HRT and 255 per 100,000 in women who had ever used HRT. There was no statistically significant association between the HRT use and subsequent development of breast cancer: relative risk (RR) = 0.8, 95% confidence interval 0.6, 1.1. There was no trend in RR by length of HRT use: less than 3 years HRT use, RR = 0.9; 3 to 9 years , RR = 0.5; 10 or more years, RR = 0.8. CONCLUSIONS: This study, based on a nationally representative cohort followed for up to 22 years, failed to find an increased risk of breast cancer associated with the use of HRT. It provides further evidence that if there is an increased risk of breast cancer associated with HRT use, this risk is small.

Randomized comparison of the antiemetic efficacy of a serotonin type 3 receptor antagonist (MDL 72,222) with a high-dose metoclopramide regimen.

This pilot randomized study compared MDL 72,222, a highly selective 5-HT3 receptor antagonist, with a high-dose metoclopramide regimen (HDM) for chemotherapy-induced nausea and vomiting. MDL 72,222 was given in 20 mg intravenous doses 30 minutes before chemotherapy, as well as 2, 6, and 12 hours after chemotherapy infusion. The HDM was composed of diphenhydramine 50 mg i.v., metoclopramide 2 mg/kg i.v., and lorazepam 0.04 mg/kg i.v. administered 30 minutes before chemotherapy and 2, 4, 6, and 8 hours after chemotherapy. Patients were randomized to either MDL 72,222 (n = 12) or the HDM (n = 12) and were matched for age, weight, Karnofsky performance status, and chemotherapy. More patients in the MDL 72,222 group had received prior cisplatin. The MDL 72,222 group and the HDM group received a mean cisplatin dose of 66 mg/m2 and 62 mg/m2, respectively. Patients were observed for retching and/or emesis for 24 hours and completed a visual analog scale (VAS) for nausea. Six MDL 72,222 and five HDM patients had no vomiting. One MDL 72,222 and two HDM patients had one episode of emesis within 24 hours of chemotherapy. The median number of emetic episodes in the first 24 hours was 0.5 for MDL 72,222 and 1.0 for HDM patients. HDM patients were frequently asleep and were not awakened for evaluation of nausea with the VAS; 58% (70 of 120) of the HDM (mean score: 19.1 mm) and 14% (17 of 119) of the MDL 72,222 (mean score: 17.1) patients could not have VAS scores obtained (X2 = 50.74, p < 0.001). MDL 72,222 had similar efficacy with less sedation, and further trials are warranted.

Granular cell tumor of intracranial meninges.

BACKGROUND: Granular cell tumor (GCT) is a benign neoplasm composed of a proliferation of round or polygonal cells that contain eosinophilic granular cytoplasm. The most common locations are tongue and subcutaneous tissue, but a variety of other sites may be involved including the central nervous system (CNS). Most CNS GCT arise in the pituitary, but rare cases involving brain and leptomeninges have been described. Extracranial GCT are usually S-100-positive, but those of the CNS, as well as the congenital variant of GCT, can be S-100-negative. CASE REPORT: We report an incidental autopsy finding of a 2.5 mm GCT that arose in the intracranial meninges overlying the anterior superior cerebellar vermis. RESULTS: The neoplasm had abundant eosinophilic, granular cytoplasm that was PAS-positive and diastase-resistant. Immunohistochemical studies showed that the neoplasm was positive for CD68 and negative for S-100, GFAP, EMA, and keratin. Thus, the immunophenotype is consistent with non-neural origin. CONCLUSION: Although this lesion in this circumstance was of no clinical significance, knowledge of the occurrence of GCT at this site broadens the differential diagnosis of eosinophilic lesions of the leptomeninges.

Malignant peripheral nerve sheath tumor with a t(X;18).

We describe an ankle tumor arising in a 16-year-old girl. The tumor demonstrated histology typical of a malignant peripheral nerve sheath tumor (MPNST), but exhibited a variant form of the (X;18) translocation associated with synovial sarcoma. Immunohistochemical stains were positive for vimentin, CD57, collagen type IV, and Bcl-2. Routine and molecular cytogenetic studies showed an unbalanced 3-way chromosomal translocation that involved chromosomes X, 18, and 1. Electron microscopic findings were noncontributory. This unusual tumor raises the following questions and possibilities: (1) As the t(X;18) suggests, could this tumor be a monophasic synovial sarcoma with the histologic features of an MPNST? (2) Or, as the histology suggests, is this tumor an MPNST that has a t(X;18)? (3) Finally, could MPNST histology, a t(X;18), and no defining immunohistochemical or electron microscopic features represent an as yet unrecognized part of a spectrum that spans from synovial sarcoma to MPNST or other spindle cell tumors?

Parental employment, family structure, and child's health insurance.

OBJECTIVE: To examine the impact of family structure on the relationship between parental employment characteristics and employer-sponsored health insurance coverage among children with employed parents in the United States. METHODS: National Health Interview Survey data for 1993-1995 was used to estimate proportions of children without employer-sponsored health insurance, by family structure, separately according to maternal and paternal employment characteristics. In addition, relative odds of being without employer-sponsored insurance were estimated, controlling for family structure and child's age, race, and poverty status. RESULTS: Children with 2 employed parents were more likely to have employer-sponsored health insurance coverage than children with 1 employed parent, even among children in 2-parent families. However, among children with employed parents, the percentage with employer-sponsored health insurance coverage varied widely, depending on the hours worked, employment sector, occupation, industry, and firm size. CONCLUSIONS: Employer-sponsored health insurance coverage for children is extremely variable, depending on employment characteristics and marital status of the parents.

Multiple-race mothers on the California birth certificate, 2000.

OBJECTIVES: Several data systems are beginning to allow respondents to report more than one race. Implications of multiple race reporting for the tabulation of race-specific birth characteristics are largely unknown. This analysis reports selected demographic characteristics and birth outcomes for multiple-race mothers, using California birth certificate data for 2000. DESIGN: Descriptive study of birth records. METHODS: Data were drawn from 530,305 electronically registered births. Demographics and birth outcomes were analyzed by race of mother for six multiple-race/ethnic groups with >300 births. RESULTS: 1.7% of mothers reported more than one race on the birth certificate. The most common multiple-race group reported was non-Hispanic Asian/White, followed by Hispanic/American Indian or Alaska Native/White. Characteristics varied widely among multiple-race subgroups, as well as between multiple-race groups and their single-race counterparts. For example, among multiple-race mothers, the proportion of births to teenage mothers was lowest among non-Hispanic Asian/White mothers (9%); this was significantly higher than percentages for non-Hispanic Asian or non-Hispanic White mothers (4% and 6%, respectively). CONCLUSIONS: Understanding the influence of multiple-race reporting on trends and comparisons in birth outcomes will be a challenge for public health researchers.

The role of leaf nitrogen content in determining turtlegrass (Thalassia testudinum) grazing by a generalized herbivore in the northeastern Gulf of Mexico.

In shallow marine environments the variability in grazing on seagrasses has been hypothesized to be controlled, in part, by the nutritive quality (i.e., nitrogen content) of their leaves. The few existing studies of the relationship between leaf nitrogen content and seagrass grazing have all found a positive relationship between leaf nitrogen content and preference by selective vertebrate grazers (i.e., the bucktooth parrotfish, green sea turtles, and dugongs). However, most marine herbivores (both vertebrate and invertebrate) are thought to be extreme generalists with broad diets of variable nutritive quality (e.g., detritus, living plants, and animals), suggesting the currently held view on the role leaf nutrient content in explaining the variability of seagrass grazing is an oversimplification.In this study, we evaluated how leaf nitrogen content influenced grazing on turtlegrass by a generalist invertebrate herbivore (the pink sea urchin Lytechinus variegatus) in the northeastern Gulf of Mexico. Using a short-term laboratory test and a longer-term field experiment, we tested the hypothesis that leaf nitrogen content controls sea-urchin grazing on seagrass leaves. We hypothesized that if poor nutritive value of seagrasses is responsible for reduced rates of feeding, then increasing leaf nitrogen concentrations should lead to increased rates of seagrass consumption by sea urchins.In the field experiment, we significantly enriched seagrass leaf nitrogen concentrations (some 10-20% depending on month) in experimental plots with a commercial fertilizer and we manipulated grazing intensity by enclosing adult sea urchins at densities that bracketed the range of average densities observed in the region (i.e., 0, 10 and 20 individuals/m(2)). Comparisons of changes in aboveground seagrass production and biomass showed no evidence that sea urchins grazed significantly more in treatments where leaf nitrogen was enriched. Because the statistical power of our test to detect such differences was low and aboveground seagrass production varied significantly among treatments, we also used a mass balance equation to estimate sea urchin consumption of nitrogen-enriched and unenriched leaves. This showed that sea urchins compensated for low nitrogen levels in our unenriched treatments by eating more leaves than in treatments where leaf nitrogen was elevated. Using a laboratory test, we also found that sea urchins ate less nitrogen-enriched seagrass than unenriched seagrass. In combination, these results show that, in contrast to findings reported for vertebrate herbivores, sea urchins feed at higher rates when offered seagrass leaves of lower leaf nitrogen content, and that low levels of leaf nitrogen are not always an effective defense against herbivores.

[Pre-syncope and syncope at the operating table--diagnostic and therapeutic possibilities]. / Präsynkopen und Synkopen am Operationstisch--diagnostische und therapeutische Möglichkeiten.

Standing in long-lasting operations can be a trigger for neurocardiogenic syncopes for the personal in the operating theatre. We report on a 37-year-old surgeon who suffered since childhood from more than 100 syncopes and presyncopes. That was the reason for him to think of giving up his profession. The head-up tilt-test proved the mechanism of a neurocardiogenic syncope. No further syncope has occurred for 16 months during the therapy with theophyllin.

Percutaneous thermal microwave ablation of thyroid nodules. Preparation, feasibility, efficiency.

UNLABELLED: Microwave ablation (MWA) is a new minimal invasive method for thermal ablation of benign thyroid nodules. In contrast to well-established radiofrequency ablation (RFA), MWA offers several advantages with similarly successful results. There has not been any use of functional imaging with 99mTc-pertechnetate and 99mTc-MIBI-scans as a mere qualitative analysis of this imaging in the field of MWA in Europe until now. The aim of this study has been to demonstrate the feasibility of MWA as well as the applicability of functional imaging to verify effectiveness with a centerspecific score. PATIENTS, METHODS: 11 patients (5 women, 6 men, average age 62.3 years) with 18 benign thyroid nodules were treated. MWA was operated under local anesthesia with a system working in a wavelength field of 902 to 928 MHz (Avecure MWG881, MedWaves, Inc. San Diego, CA). Pre- and postablative scans were controlled by two specialists in nuclear medicine with longtime work experience. RESULTS: A center specific functional imaging score (CSFIS) was defined, a decrease of 1.4 points at an average was noticeable (range 1-3 points). In 66.7% (n = 12) of all nodules the score decreased by 1 point, 27.8% (n = 5) by 2 points and 5.6% (n = 1) by 3 points. The treatment was well tolerated and no severe complications were observed. CONCLUSION: The preliminary data suggests that MWA is an effective method to treat benign thyroid nodules. Functional imaging is a promising technique for early verification of effectiveness of thermal ablation.