Fracture strength of monolithic and glass-soldered ceramic subcomponents of 5-unit fixed dental prosthesis

Purpose

Zirconium dioxide ceramic has been successfully introduced as a framework material for fixed dental prostheses. To reduce manufacturing constraints, joining of subcomponents could be a promising approach to increase the mechanical performance of long-span fixed dental prostheses. In this experimental study, the biomechanical behavior of monolithic and soldered framework specimens for fixed dental prostheses made of Y-TZP was investigated.

Materials and methods

Framework specimens (n = 80) of 5-unit fixed dental prostheses made of Y-TZP were prepared and divided into 10 equal groups. The specimens were monolithic or composed of subcomponents, which were joined using a silicate-based glass solder. Thereby, three joint geometries (diagonal, vertical with an occlusal cap, and dental attachment-based) were investigated. Moreover, the groups differed based on the mechanical test (static vs. dynamic) and further processing (veneered vs. unveneered). The framework specimens were cemented on alumina-based jaw models, where the canine and second molar were acting as abutments before a point-load was applied. In addition, µCT scans and microscopic fractography were used to evaluate the quality of soldered joints and to determine the causes of fracture.

Results

The determined fracture loads of the different unveneered framework specimens in static testing did not vary significantly (p = 1). Adding a veneering layer significantly increased the mechanical strength for monolithic framework specimens from 1196.29 ± 203.79 N to 1606.85 ± 128.49 N (p = 0.008). In case of soldered specimens with a dental attachment-based geometry, the mechanical strength increased from 1159.42 ± 85.65 N to 1249.53 ± 191.55 N (p = 1). Within the dynamic testing, no differences were observed between monolithic and soldered framework specimens. µCT scans and fractography proved that the dental attachment-based joining geometry offers the highest quality.

Conclusion

Using glass soldering technology, subcomponents of 5-unit framework specimens made of Y-TZP could be joined with mechanical properties comparable to those of monolithic frameworks.     

Anatomic attachment of the ACL. Comparison between radiological and CT analysis

Purpose  

The following hypothesis was tested: the location of the tibial and femoral anterior cruciate ligament (ACL) attachments will differ according to the measurement technique (plain radiographs or CT-scan) in relation to the anatomic frame of reference.     

Plasma cell leukemia with an unusual karyotype and prolonged survival with oral alkylating agent therapy

Summary A patient with primary plasma cell leukemia (PCL) is presented, who had an excellent response to high-dose cyclophosphamide and prolonged survival. The sole cytogenetic abnormality detected in the bone marrow was monosomy 18. Although this karyotypic aberration has been previously described in PCL, it generally occurs associated with additional abnormalities. The peripheral blood plasma cells from this patient reacted intracellularly with the monoclonal antibody OKM-1, which binds to myeloid cells at and above the level of myelocytes and to monocytes. This finding supports the idea of a common precursor cell for plasma cells and cells of the myelomonocytic lineage.Supported in part by grant from the Chemotherapy FoundationSupported in part by a grant from the Stratton Foundation     

Plasma cell leukemia with an unusual karyotype and prolonged survival following oral alkylating agent therapy

Summary A patient with primary plasma cell leukemia (PCL) is presented who had an excellent response to high-dole cyclophosphamide and prolonged survival. The sole cytogenetic abnormality detected in the bone marrow was monosomy 18. Although this karyotypic aberration has been previously described in PCL, it generally occurs associated with additional abnormalities. The peripheral blood plasma cells from this patient reacted intracellularly with the monoclonal antibody OKM-1, which binds to myeloid cells at and above the level of myelocytes and to monocytes. This finding supports a common precursor cell for plasma cells and cells of the myelomonocytic lineage.Supported in part by grant from the Chemotherapy FoundationSupported in part by a grant from the Stratton Foundation     

High-dose carmustine, etoposide, and cisplatin and autologous bone marrow transplantation for relapsed and refractory lymphoma.

PURPOSE: We determined the toxicity and efficacy of a new preparative autologous bone marrow transplantation (ABMT) regimen in patients with relapsed or refractory non-Hodgkin's lymphoma or Hodgkin's disease. PATIENTS AND METHODS: Forty-four non-Hodgkin's lymphoma and 35 Hodgkin's disease patients 16 to 63 years of age were given intravenous carmustine (BCNU) 600 to 1,050 mg/m2, etoposide 2,400 to 3,000 mg/m2, and cisplatin 200 mg/m2 (BEP) and ABMT. Fifty-nine patients also received 15 to 20 Gy local radiation (involved-field radiotherapy [RI]) to active or previously bulky (> 5 cm) disease sites. RESULTS: Nonhematologic toxicities included nausea, vomiting, high-tone hearing loss, stomatitis, esophagitis, diarrhea, and hepatic and pulmonary toxicity. Two patients died within 40 days of marrow infusion as a result of sepsis and one patient died 7 months after transplant as a result of pulmonary fibrosis. Complete remissions (CRs) were noted in 72% (n = 57) of patients (n = 33 non-Hodgkin's lymphoma; n = 24 Hodgkin's disease). Forty patients (51%) remained alive and disease-free (n = 24 non-Hodgkin's lymphoma; n = 16 Hodgkin's disease) at a median of 17 (range, 8 to 57) months after marrow reinfusion. CONCLUSIONS: This regimen seems to be effective for relapsed lymphoma patients whose disease continues to exhibit chemotherapy sensitivity (16 of 24 [67%] disease-free). Furthermore, this regimen seems to be effective in patients who have never attained a CR (seven of 19 [37%] disease-free).     

Multilayered structure based on poly(N,N-dimethyl-acrylamide-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) prepared in a multiphase gelation process

The study is devoted to the preparation of a multi-membrane gel system based on poly(N,N-dimethyl-acrylamide-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) copolymer. The complex supra-structure was realized by layer by layer deposition technique, from the gel-core to the periphery by crosslinking poly(N,N-dimethyl-acrylamide-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) (P(DMA-co-U)) with N,N′-methylene-bis-acrylamide and using as well β-cyclodextrin with double purpose as compound for constructing further the edge of the interfacial supramolecular assemblies and to improve the host-guest complexation of further bioactive compounds. Basic copolymer has dual thermo- and pH sensitive character. The multi-membrane ‘onion-like’ gel system was tested as matrix for embedding Norfloxacin. Hematologic, biochemical, immunologic studies used to determine the biocompatibility of multi-membrane gel structures loaded with drug that directly contact living tissue provided a reasonable assessment of safety as implants. Histopathologic exams did not reveal any disturbances of the normal liver architecture in animals with multi-membrane gel system containing Norfloxacin compared to control group with sterile cotton pellets implant. Good biocompatibility for the implants based on multi-membrane gel structures loaded with drug were achieved from the in vivo tests these suggesting that biomaterials may be suitable for in vivo use as a local drug delivery system.     

TRPM8, a sensor for mild cooling in mammalian sensory nerve endings

Temperature sensing is a crucial feature of the nervous system, enabling organisms to avoid physical danger and choose optimal environments for survival. TRPM8 (Transient Receptor Potential Melastatin type 8) belongs to a select group of ion channels which are gated by changes in temperature, are expressed in sensory nerves and/or skin cells and may be involved in temperature sensing. This channel is activated by a moderate decrease in temperature, with a threshold of approximately 25 °C in heterologous expression systems, and by a variety of natural and synthetic compounds, including menthol. While the physiological role of TRPM8 as a transducer of gentle cooling is widely accepted, its involvement in acute noxious cold sensing in healthy tissues is still under debate. Although accumulating evidence indicates that TRPM8 is involved in neuropathic cold allodynia, in some animal models of nerve injury peripheral and central activation of TRPM8 is followed by analgesia. A variety of inflammatory mediators, including bradykinin and prostaglandin E(2), modulate TRPM8 by inhibiting the channel and shifting its activation threshold to colder temperatures, most likely counteracting the analgesic action of TRPM8. While important progress has been made in unraveling the biophysical features of TRPM8, including the revelation of its voltage dependence, the precise mechanism involved in temperature sensing by this channel is still not completely understood. This article will review the current status of knowledge regarding the (patho)physiological role(s) of TRPM8, its modulation by inflammatory mediators, the signaling pathways involved in this regulation, and the biophysical properties of the channel.