Antibacterial activity of various root canal sealers and root-end filling materials in dentin blocks infected ex vivo with Enterococcus faecalis.

OBJECTIVE: The aim was to investigate the antibacterial activity of the root-end filling materials MTA and IRM, different endodontic sealers and calcium hydroxide [Ca(OH)2] in experimentally infected dentinal tubules. MATERIALS AND METHODS: Ninety-four human root segments were prepared and the root canals were enlarged to ISO size 90. After smear removal, the specimens were infected with Enterococcus faecalis for 3 weeks. The roots were divided into eight groups and filled either with MTA, IRM, Ca(OH)2, gutta-percha and EndoRez (ER)/GuttaFlow (GF)/AH Plus (AH+) or with Resilon and Epiphany (EpRe). One group of specimens was left unfilled for control. Half of the specimens were treated for 1 day and the other half for 7 days in humid conditions at 37°C. Dentin samples from each canal were collected by enlarging the canals to ISO size 150; thus a dentinal depth of 300 µm was sampled. The number of cultivable bacteria was determined for each specimen. Statistical significance was set to 5%. RESULTS: After 1-day or 7-days of treatment, compared to control, all materials (except ER and GF at day 7) significantly reduced the number of bacteria. At day 1 and day 7, no significant difference was found between ER and GF and between Ca(OH)2, AH+, EpRe, IRM and MTA. However, a significant difference was found between these two groups of materials (except between GF and EpRe at day 7). Significantly more bacteria were cultured in the ER, GF, EpRe and IRM groups at day 7 compared to day 1. CONCLUSIONS: All materials exerted varying degrees of antibacterial activity which generally tended to decrease with time. The most stable antibacterial effect throughout the 7-day period was for Ca(OH)2, AH+ and MTA.

Synthesis, characterization, and antimicrobial activity of poly(acrylonitrile-co-methyl methacrylate) with silver nanoparticles.

Nanotechnology is expected to open some new aspects to fight and prevent diseases using atomic-scale tailoring of materials. The main aim of this study is to biosynthesize silver nanoparticles (AgNPs) using Trichoderma viride (HQ438699); the metabolite of this fungus will help either in reduction of the silver nitrate-adding active materials which will be loaded on the surface of the produced AgNPs. Poly(acrylonitrile-co-methyl methacrylate) copolymer (poly (AN-co-MMA)) was grafted with the prepared AgNPs. The poly(AN-co-MMA)/AgNPs were examined against ten different pathogenic bacterial strains, and the result was compared with another four different generic antibiotics. The produced poly(AN-co-MMA)/AgNPs showed high antibacterial activity compared with the four standard antibiotics. Moreover, the grafting of these AgNPs into the copolymer has potential application in the biomedical field.

One- versus two-visit endodontic treatment of teeth with apical periodontitis: a histobacteriologic study.

INTRODUCTION: This study analyzed the in vivo microbiological status of the root canal systems of mesial roots of mandibular molars with primary apical periodontitis after 1- or 2-visit endodontic treatment. METHODS: Mesial root canals were instrumented by using either a combination of K3 and LightSpeed instruments (mesiobuccal canals) or the ProTaper system (mesiolingual canals), with 5% NaOCl irrigation. Patency files were used. Smear layer was removed, and a final rinse with 5 mL of 2% chlorhexidine was performed. In the 2-visit group (7 roots, 14 canals), canals were medicated with calcium hydroxide for 1 week and then obturated by using the continuous wave of compaction technique. In the 1-visit group (6 roots, 12 canals), canals were immediately obturated after chemomechanical procedures. Teeth were extracted 1 week after root canal instrumentation and processed for histobacteriologic analysis. RESULTS: In the 1-visit group, no case was completely free of bacteria; residual bacteria occurred in the main root canal (5 of 6 cases), isthmus (5 of 6), apical ramifications (4 of 6), and dentinal tubules (5 of 6). In the 2-visit group, 2 cases were rendered bacteria-free; residual bacteria were found in the main canal only in 2 cases (none of them with persistent dentinal tubule infection), in the isthmus (4 of 7 cases), and in ramifications (2 of 7). The 2 instrumentation techniques performed similarly. When filling material was observed in ramifications, it was usually intermixed with necrotic tissue, debris, and bacteria. CONCLUSIONS: The 2-visit protocol by using an interappointment medication with calcium hydroxide resulted in improved microbiological status of the root canal system when compared with the 1-visit protocol. Residual bacteria were more frequent and abundant in ramifications, isthmuses, and dentinal tubules when root canals were treated without an interappointment medication. Apical ramifications and isthmuses were never completely filled. The use of an antibacterial interappointment agent is necessary to maximize bacterial reduction before filling.

Experimental model: dye penetration of extensive interim restorations used during endodontic treatment while under load in a multiple axis chewing simulator.

The purpose of this study was to design an experimental model that allowed extensive endodontic interim restorations to be tested for dye penetration while under simulated masticatory load. Extracted premolar teeth had standardized mesio-occluso-distal cavities prepared, and the root canals were instrumented. A cotton wool pellet was placed in the pulp chamber, and the cavities were restored with Cavit, IRM, Ketac-Fil Plus, Ketac-Silver, or composite resin (Z100). They were subjected to the equivalent of 3 months of clinical load while exposed to methylene blue dye. Results of this study could not support IRM as a suitable interim endodontic restorative material to use in extensive cavities. The dye penetration in the Ketac-Fil Plus and Ketac-Silver specimens was not predictable, and the results suggested Cavit and Z100 composite resin require further investigations as potentially useful materials for this purpose.

Cementoplastia de malformaciones arteriovenosas maxilofaciales con compromiso óseo / Cementoplastia of maxilofaciales arteriovenosas malformations with bony commitment

Propósito: El objetivo del trabajo es describir este tipo de abordaje terapéutico en pacientes con malformaciones arterio-venosas de la región maxilofacial con compromiso óseo. Material y Métodos: Revisión retrospectiva de 3 pacientes portadores de malformaciones arteriovenosas de alto flujo con compromiso maxilofacial, tratados en nuestro servicio mediante embolización superselectiva vía arterial, percutánea y punción ósea con inyección de Metilmetacrilato. Resultados: La edad de los pacientes fue 8, 12 y 19 años, 2 eran de sexo masculino y uno femenino. Todos presentaron historia de homorragias a repetición que requirieron transfudiones y reiteradas sesiones de embolización intraarterial previas. El estudio angiográfico mostró complejas malformaciones de alto flujo de la región maxilofacial con compromiso óseo evidente en exámenes radiológicos (radiografía simple, tomografía computada y resonancia magnética). Se realizó punción percutánea de la lesión bajo radioscopia e inyección de Metilmetacrilato como tratamiento complementario a la embolización superselectiva vía arterial. En los casos de hemorragia aguda severa el tratamiento produjo rápida hemostasia. En el seguimiento a seis meses no se registraron nuevos episodios de sangrado. Conclusión: En nuestra experiencia, la reconstrucción ósea mediante cementoplastia con inyección de Metilmetacrilato en malformaciones arterio-venosas maxilofaciales es un procedimiento seguro y eficaz como complemento del abordaje terapéutico de estas complejas lesiones.

[Characterization of custom-made biomaterials containing antibiotics]. / Charakterisierung arzneimittelhaltiger Biomaterialien als kundenspezifische Sonderanfertigung.

The aim of this study was to evaluate the quality of custom-made antibiotic carriers which are produced for hospitals in a central service laboratory. These sterile products, made according to antibiogram, showed quality parameters which are comparable with commercially available products in terms of antibiotic release and other relevant properties.

Estudio de cesión de cefalosporinas incluidas en cementos oseos acrílicos / Release assay of cephalosporyns included in acrylic bone cements

El progresivo aumento de la esperanza de vida ha originado un notable incremento de las patologías degenerativas óseas que requieren implatación de prótesis. Estas intervenciones quirúrgicas conllevan en ocasiones serias complicaciones entre las que cabe destacar las infecciones bacterianas. La gentamicina es el agente antimicrobiano de elección incluido en los cementos acrílicos para la prevención de dichas osteomielitis. Sin embargo, debido a la creciente aparición de cepas bacterianas resistentes a la gentamicina, en este trabajo se propone la utilización de terapia local antibacteriana con otros antibióticos del grupo de las cefalosporinas como son la ceftazidima y la cefotaxima: En el presente estudio, se validan los métodos analíticos utilizados para la cuantificación de las cefalosporinas, que se basan en la formación de complejos coloreados tras la reacción de la ceftazidima o cefotaxima con el cloruro de paladio como reactivo y la posterior determinación espectrofotométrica UV-Vis de los mismos a las longitudes de onda de 354 y 280 nm respectivamente. Posteriormente, se ha realizado un estudio de cesión "in vitro"de estos antibióticos tras su inclusión en cementos óseos acrílicos de polimetilmetacrilato (PMMA) (AU)

Effect of adding resorbable calcium sulfate to grafting materials on early bone regeneration in osseous defects in rabbits.

This experiment was designed to study the osteogenic potential of adding medical-grade resorbable calcium sulfate mixture to grafting materials for filling osseous defects. Twelve New Zealand rabbits were divided into an active group of 10 animals and a control group of 2 animals. The median condyle of each femur was drilled to create 8-mm-deep cavities. Active osseous defects consisted of 20 cavities and were filled with Osteograf, BOP, or Capset (calcium sulfate) alone; a mixture of Osteograf and Capset; or a mixture of BOP and Capset. Osteograf and BOP were each mixed with Capset in a 4:1 ratio. Each grafting material filled 4 osseous cavities, and 4 osseous cavities were left unfilled to act as controls. The observation period was 8 weeks. Block sections of the femoral heads were prepared for decalcified histologic assessment. It appeared that mixing grafting materials with calcium sulfate powder in a 4:1 ratio, respectively, facilitated the process of osteogenesis and increased new bone bonding to remnants of the grafting materials, in spite of the poor osteoconductive property of BOP and moderate osteoconductivity of Osteograf. However, calcium sulfate material alone is not recommended for use as a bone filler.

Intra-operative antibiotic bead maker--point of technique.

Chronic osteomyelitis is a disease of soft tissue and bone and it is common in the developing countries. The management of this debilitating disease requires the delivery of the appropriate chemotherapeutic agent at the site of the infection after adequate debridement. The search for a suitable carrier for these chemotherapeutic agents is the advent of the 'septopal' or gentamycin-polymethylmethacrylate (gentamycin-PMMA) beads. Septopal beads are expensive and are not affordable by patients in the developing countries. Moreover, most of the micro-organisms (mixed flora) responsible for chronic osteomyelitis in our hospitals are sensitive to ceftriaxone and only in a few cases were gentamycin-sensitive micro-organisms isolated. Therefore, it was imperative that patient-specific and antibiotic-specific PMMA beads would be the way forward and this is the reasoning behind the production of the intra-operative antibiotic bead maker (IABM) and the point of technique is hereby presented.

Leakage in roots coronally sealed with different temporary fillings.

This study was aimed at determining the ability of different coronal temporary fillings to prevent corono-apical penetration of bacteria. A total of 103 human teeth, including three controls, were instrumented, obturated with gutta-percha, coronally sealed with either Cavit, Intermediate Restorative Material (IRM), glass-ionomer cement, Cavit/glass-ionomer cement, or IRM/glass-ionomer cement, respectively. Each root was fixed with wax between two chambers: the coronal chamber harboring soy broth with 10(8) colony-forming units of Streptococcus mutans/ml, the apical chamber containing sterile soy broth. The latter was checked daily for turbidity, indicating corono-apical penetration of bacteria. The Cavit group, the IRM group, and the Cavit/glass-ionomer cement group showed significantly more leakage than the glass-ionomer cement group of the IRM/glass-ionomer cement group. If a sample leaked, all except one (IRM/glass-ionomer cement) leaked before day 12. This in vitro study seems to indicate that only glass-ionomer cement and IRM combined with glass-ionomer cement may prevent bacterial penetration to the periapex of root-filled teeth over a 1-month period.

Thermal effects of acrylic cementation at bone tumour sites.

The use of acrylic bone cement as an adjunct to surgical excision of giant cell tumour of bone appears to reduce the incidence of tumour recurrence. Possible mechanisms for this apparent tumour inhibition include cytotoxic effects from the methylmethacrylate monomer and tissue hyperthermia from the heat of polymerization of the cement. This work presents a method for the prediction of temperature fields and resulting tissue necrosis arising from the implantation of polymethylmethacrylate (PMMA) at the site of a curretted giant cell tumour of bone. This is accomplished using a two-dimensional model based on geometry obtained from digitized MRI images of the distal femur. A general-coordinate, non-orthogonal grid generation technique is used and solutions are obtained with an alternating-direction implicit (ADI) finite-difference scheme. The nodal temperature histories are then used to evaluate the effect of variable defect size on the zone of thermally induced cell necrosis. The results suggest the depth of the necrotic region is quite sensitive to the size of the implant. In at least some cases, the heating effect is sufficient to cause significant necrosis of tumorigenic cells. Implanting a large mass of acrylic may risk overkill, damaging substantial amounts of healthy tissue.

An in-vitro comparative study of the retention of grooved and flat endodontic posts in treated root canals using two different types of cements.

This study evaluated and compared the retentive capability of performed cast posts in endodontically treated premolar teeth using the following: 1--smooth versus grooved post design 2--surface treatment of the root canals with either 17% EDTA followed by 2.25% Naocl or using Naocl only. 3--cementation of the posts with either polycarboxylate cement or C & B Metabond. Cast metal posts were made, cemented in root canals and divided into groups representing combinations of variables. The force required for post removal were recorded and statistically analysed. The results indicated that cementation of the grooved cast metal post with polycarboxylate cement after removal of the smear layer was the most retentive system. More over C & B Metabond resin cement with any post design in presence or absence of smear layer gave high retentive values.

Acetabular cement temperature in arthroplasty. Effect of water cooling in 19 cases.

In 19 patients who underwent total hip arthroplasty the temperature was studied at the bone-cement interface in the acetabulum during the polymethyl methacrylate curing process. To evaluate the effect of fluid cooling, the patients were randomized into two groups: one group with no irrigation, the other with continuous irrigation with Ringer solution during cement curing. The temperature was recorded with a thermocouple at the bone-cement interface. Without water cooling, the median maximum temperature was 49 (41-67) degrees C. In 9 out of 11 patients the temperature elevations were sufficient to cause impaired bone regeneration or thermal necrosis of bone. Continuous water irrigation reduced the amount of heat at the bone-cement interface; median maximum temperature was 41 (37-48) degrees C.

Alumina versus polyethylene in total knee arthroplasty.

The cementless alumina total knee prosthesis, which uses alumina in the portions coming in contact with the bone and a combination of alumina and ultra-high molecular-weight polyethylene (UHMWPE) in the sliding portions, is referred to as a total condylar. Alumina total knee arthroplasty was performed on 137 patients, including 103 rheumatoid arthritis (RA) and 34 osteoarthrosis (OA) patients, from January 1982 to February 1985. The follow-up period was seven years 11 months and four years ten months, respectively. At follow-up evaluation, 108 patients were available for clinical and roentgenographic examinations, amounting to a 79% follow-up rate. At follow-up examination, 67 joints (62%) were completely pain free and 28 joints (26%) caused slight pain on bearing weight. Walking ability was recovered moderately in RA and markedly in OA. In RA, 14 of 84 knees were cemented and one knee was treated with loosening. Of 72 cementless implantations, 55 sustained displacing distally and one sustained loosening in the tibia, whereas 31 sustained displacing proximally and six sustained loosening in the femur. In OA, 21 cementless knees had 17 displacings in the tibia, and ten displacings and two loosenings in the femur. Scanning electron microscopy (SEM) observation of the UHMWPE surface in tibial plates revealed smoothing and burnishing. Alumina is far superior to metal for the sliding part, although it is not always best for the portion in contact with the bone. To resolve these problems, for cementless fixation, anchoring portions of Ti alloy and alumina implants were covered with beads and coated with hydroxyapatite. For cement fixation, "the interface bioactive bone cement technique" interposing hydroxyapatite granules between bone and cement was performed.

Methotrexate diffusion from acrylic cement. Local chemotherapy for bone tumours.

We investigated the possible use of acrylic cement containing chemotherapeutic drugs in the treatment of malignant lesions in bone. The diffusion of methotrexate (MTX) from methylpolymethacrylate implants was studied in vitro: polymerisation of the cement did not destroy the drug; liberation began immediately and about 10% was released by 18 hours. Some release continued for as long as six months. In vivo experiments on rats with induced osteosarcoma showed that MTX in cement had both local and general effects which were dependent on the dosage. A series of 17 large dogs with spontaneous osteosarcoma were then treated by local resection and cement containing MTX. General chemotherapeutic effects were detectable from 2 hours to 5 days, survival was increased and local recurrence was reduced, but there were four cases of delayed wound healing. Preliminary studies in human patients confirm the possibility that this method of local chemotherapy could be a useful addition to the treatment of malignant tumours of bone.

Comparative strength of anterior spinal fixation with bone graft or polymethylmethacrylate. Experimental operations and observations on dogs.

In 23 dogs, polymethylmethacrylate (PMMA) was safely implanted in the region of the spinal cord. The dogs were treated by bone or cement fixation after anterior excision of a single cervical vertebral body. Fixation was compared at 0-18 weeks, with control values obtained from 11 dogs. Anterior cement fixation did not displace after 18 weeks. The anterior bone graft appeared to achieve adequate fixation strength around six weeks. The strength of the bone-graft fixation increased, while that of cement fixation decreased somewhat with time. At all time intervals, the ratio of energy absorption to structural failure was somewhat higher with bone graft than with PMMA.

[Antisilicotic action and side effects of polypyridylethyl-methacrylate iodomethylate]. / O protivosilikoticheskom i pobochnom deistvii iodmetilata polipiridilétilmetakrilata.

Antisilicotic and side effects of a new polymer synthetized on the basis of polymethacrylic acid were studied. The polymer not only inhibited the development of silicotic sclerosis but also induced its partial reverse development. As regards the effect intensity it appeared to be equal to highly effective polyvinylpyridine-N-oxide. The data obtained indicate the necessity of a further study of the new antisilicotic polymer with a purpose of recommending it for clinical trials.