Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Pliability”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed2006

Aging studies of light cured dimethacrylate-based dental resins and a resin composite in water or ethanol/water.

OBJECTIVE: To study the aging of neat resins, prepared from bis-GMA, UDMA, D(3)MA or a mixture of bis-GMA/UDMA/D(3)MA (65/20/15 w/w/w), in water or 75% (v/v) ethanol/water 37 degrees C. Also the study of aging of Heliomolar RO, which is a radiopaque, microfilled, light cured composite, the resin matrix of which is the copolymer of bis-GMA/UDMA/D(3)MA (65/20/15 w/w/w). METHODS: Samples of neat resins and Heliomolar RO prepared by light curing were immersed in water or 75% (v/v) ethanol/water 37 degrees C, for 1, 7 or 30 days. Then the flexural and tensile strength were determined. The fractured surface of samples after the flexural tests was observed by scanning electron microscopy. RESULTS: Bis-GMA and copolymer resin did not showed any significant change in mechanical properties after immersion in water or 75% (v/v) ethanol/water 37 degrees C, for 30 days. On the contrary UDMA, D(3)MA and the composite Heliomolar RO showed a significant decrease. SIGNIFICANCE: The results obtained showed that the effect of aging in water or ethanol/water solution on mechanical properties of a light cured dimethacrylate resin depends on the chemical structure of resin. In the case of resin composite this effect depends on the filler-matrix bond strength.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2006

Mechanical and physical properties of carbon-graphite fiber-reinforced polymers intended for implant suprastructures.

OBJECTIVES: Mechanical properties and quality of fiber/matrix adhesion of poly(methyl methacrylate) (PMMA)-based materials, reinforced with carbon-graphite (CG) fibers that are able to remain in a plastic state until polymerization, were examined. METHODS: Tubes of cleaned braided CG fibers were treated with a sizing resin. Two resin mixtures, resin A and resin B, stable in the fluid state and containing different cross-linking agents, were reinforced with CG fiber loadings of 24, 36, and 47 wt% (20, 29, and 38 vol.%). In addition, resin B was reinforced with 58 wt% (47 vol.%). After heat-polymerization, flexural strength and modulus were evaluated, both dry and after water storage. Coefficient of thermal expansion, longitudinally and in the transverse direction of the specimens, was determined. Adhesion between fibers and matrix was evaluated with scanning electron microscopy (SEM). RESULTS: Flexural properties and linear coefficient of thermal expansion were similar for both fiber composites. With increased fiber loading, flexural properties increased. For 47 wt% fibers in polymer A the flexural strength was 547.7 (28.12) MPa and for polymer B 563.3 (89.24) MPa when water saturated. Linear coefficient of thermal expansion was for 47 wt% CG fiber-reinforced polymers; -2.5 x 10(-6) degrees C-1 longitudinally and 62.4 x 10(-6) degrees C-1 in the transverse direction of the specimens. SEM revealed good adhesion between fibers and matrix. More porosity was observed with fiber loading of 58 wt%. CONCLUSIONS: The fiber treatment and the developed resin matrices resulted in good adhesion between CG fibers and matrix. The properties observed indicate a potential for implant-retained prostheses.

Carbon↗
PubMed2006

Effect of thermal cycling on composites reinforced with two differently sized silica-glass fibers.

OBJECTIVES: To evaluate the effects of thermal cycling on the flexural properties of composites reinforced with two differently sized fibers. METHODS: Acid-washed, woven, fused silica-glass fibers, were heat-treated at 500 degrees C, silanized and sized with one of two sizing resins (linear poly(butyl methacrylate)) (PBMA), cross-linked poly(methyl methacrylate) (PMMA). Subsequently the fibers were incorporated into a polymer matrix. Two test groups with fibers and one control group without fibers were prepared. The flexural properties of the composite reinforced with linear PBMA-sized fibers were evaluated by 3-point bend testing before thermal cycling. The specimens from all three groups were thermally cycled in water (12,000 cycles, 5/55 degrees C, dwell time 30 s), and afterwards tested by 3-point bending. SEM micrographs were taken of the fibers and of the fractured fiber reinforced composites (FRC). RESULTS: The reduction of ultimate flexural strength after thermal cycling was less than 20% of that prior to thermal cycling for composites reinforced with linear PBMA-sized silica-glass fibers. The flexural strength of the composite reinforced with cross-linked PMMA-sized fibers was reduced to less than half of the initial value. SIGNIFICANCE: This study demonstrated that thermal cycling differently influences the flexural properties of composites reinforced with different sized silica-glass fibers. The interfacial linear PBMA-sizing polymer acts as a stress-bearing component for the high interfacial stresses during thermal cycling due to the flexible structure of the linear PBMA above Tg. The cross-linked PMMA-sizing, however, acts as a rigid component and therefore causes adhesive fracture between the fibers and matrix after the fatigue process of thermal cycling and flexural fracture.

Composite Resins↗
PubMed2006

Effect of fiber architecture on flexural characteristics and fracture of fiber-reinforced dental composites.

OBJECTIVE: The aim of this study was to compare and elucidate the differences in damage mechanisms and response of fiber-reinforced dental resin composites based on three different brands under flexural loading. The types of reinforcement consisted of a unidirectional E-glass prepreg (Splint-It from Jeneric/Petron Inc.), an ultrahigh molecular weight polyethylene fiber based biaxial braid (Connect, Kerr) and an ultrahigh molecular weight polyethylene fiber based leno-weave (Ribbond). METHODS: Three different commercially available fiber reinforcing systems were used to fabricate rectangular bars, with the fiber reinforcement close to the tensile face, which were tested in flexure with an emphasis on studying damage mechanisms and response. Eight specimens (n=8) of each type were tested. Overall energy capacity as well as flexural strength and modulus were determined and results compared in light of the different abilities of the architectures used. RESULTS: Under flexural loading unreinforced and unidirectional prepreg reinforced dental composites failed in a brittle fashion, whereas the braid and leno-weave reinforced materials underwent significant deformation without rupture. The braid reinforced specimens showed the highest peak load. The addition of the unidirectional to the matrix resulted in an average strain of 0.06mm/mm which is 50% greater than the capacity of the unreinforced matrix, whereas the addition of the braid and leno-weave resulted in increases of 119 and 126%, respectively, emphasizing the higher capacity of both the UHM polyethylene fibers and the architectures to hold together without rupture under flexural loading. The addition of the fiber reinforcement substantially increases the level of strain energy in the specimens with the maximum being attained in the braid reinforced specimens with a 433% increase in energy absorption capability above the unreinforced case. The minimum scatter and highest consistency in response is seen in the leno-weave reinforced specimens due to the details of the architecture which restrict fabric shearing and movement during placement. SIGNIFICANCE: It is crucial that the appropriate selection of fiber architectures be made not just from a perspective of highest strength, but overall damage tolerance and energy absorption. Differences in weaves and architectures can result in substantially different performance and appropriate selection can mitigate premature and catastrophic failure. The study provides details of materials level response characteristics which are useful in selection of the fiber reinforcement based on specifics of application.

Composite Resins↗
PubMed2006

Influence of triaxial braid denier on ribbon-based fiber reinforced dental composites.

OBJECTIVES: The aim of the study was to compare the mechanical characteristics of two ultrahigh molecular weight polyethylene (UHMWPE) fiber-based triaxial braided reinforcements having different denier braider yarns used in fiber reinforced dental composites to elucidate differences in response and damage under flexural loading. METHODS: Two commercially available triaxial braided reinforcing systems, differing in denier of the axial and braider yarns, using ultra high molecular weight polyethylene (UHMWPE) were used to reinforce rectangular bars towards the tensile surface which were tested in flexure. Mechanical characteristics including energy absorption were determined and results were compared based on Tukey post-test analysis and Weibull probability. Limited fatigue testing was also conducted for 100, 1000, and 10,000 cycles at a level of 75% of peak load. The effect of the braid denier on damage mechanisms was studied microscopically. RESULTS: The use of the triaxially braided ribbon as fiber reinforcement in the dental composite results in significant enhancement in flexural performance over that of the unreinforced dental composite (179% and 183% increase for the "thin" and "dense" braid reinforced specimens, respectively), with a fairly ductile, non-catastrophic post-peak response. With the exception of strain at peak load, there was very little difference between the performance from the two braid architectures. The intrinsic nature of the triaxial braid also results in very little decrease in flexural strength as a result of fatigue cycling at 75% of peak load. Use of the braids results in peak load levels which are substantially higher than those corresponding to points at which the dentin and unreinforced dental composites would fail. The total energy at peak load level is 56.8 and 60.7 times that at the level that dentin would fail if the reinforcement were not placed for the "thin" and "dense" reinforced braid reinforced composites, respectively. SIGNIFICANCE: The research shows that in addition to enhancement in flexural performance characteristics, the use of a triaxial braid provides significant damage tolerance and fatigue resistance through its characteristic architecture wherein axial fibers are uncrimped and braider yarns provide shear resistance and enable local arrest of microcracks. Further, it is demonstrated that the decrease in braider yarn denier does not have a detrimental effect, with differences in performance characteristics, being in the main, statistically insignificant. This allows use of thinner reinforcement which provides ease of placement and better bonding without loss in performance.

Composite Resins↗
PubMed2006

Three-dimensional finite element analysis of strain and stress distributions in endodontically treated maxillary central incisors restored with different post, core and crown materials.

OBJECTIVES: The present comparative analysis aimed at evaluating which combination of restorative materials resulted in the most homogeneous stress and strain distributions. METHODS: A three-dimensional finite element analysis was performed. All the nodes on the external surface of the root were constrained in all directions. Eighteen experimental models with different material properties and configurations were simulated. An arbitrary load of 10N was applied at 60 degrees angle with tooth longitudinal axis on the palatal surface of the crown. Von Mises (equivalent stresses) energetic criterion was chosen. RESULTS: In all the models the values of both strain and stress recorded at the middle third of the buccal aspect of the root surface were at their maxima. On the contrary, the minimum values were noticed at level of both the apical portion of the post and the root apex. The maximum stresses were evidenced at level of the cemento-enamel junction (CEJ) on both the buccal and palatal aspects of root cement and dentin. Stress progressively decreased from the outer to the inner part of the root and from the CEJ towards the incisal margin of the crown as well. SIGNIFICANCE: The results of the present study would allow clinicians to make an informed choice from among available materials to restore endodontically treated teeth.

Cementation↗
PubMed2006

A novel comonomer-free light-cured glass-ionomer cement for reduced cytotoxicity and enhanced mechanical strength.

OBJECTIVE: The objective of this study was to develop a novel comonomer-free light-cured glass-ionomer system based on the 4-arm star-shape poly(acrylic acid). The mechanical strengths and in vitro cytotoxicity of the formed system were evaluated and compared with those of several representative commercial glass-ionomer cements. MATERIALS AND METHODS: The 4-arm poly(acrylic acid) was synthesized using ATRP and tethered with glycidyl methacrylate (GM). The GM-tethered polymer was formulated with water, photo-initiators, and Fuji II LC filler. Fuji II, Fuji II LC and Vitremer were used for comparison. Compressive strength (CS) and MTT assay were used as tools to evaluate the mechanical strengths and in vitro cytotoxicity of the cements, respectively. RESULTS: The experimental cement exhibited significantly high compressive, diametral tensile and flexural strengths as compared to commercial glass-ionomer cements, Fuji II, Fuji II LC and Vitremer. The effects of polymer/water (P/W) ratio, GM-grafting ratio, glass powder/polymer liquid (P/L) ratio and aging in water on strengths were significant. Similar to conventional glass-ionomer cement Fuji II, the eluates from the experimental cement showed little in vitro cytotoxicity to Balb/c mouse fibroblast cells, as compared to Fuji II LC and Vitremer that contain HEMA as a comonomer. CONCLUSIONS: It appears that this novel comonomer-free light-cured glass-ionomer cement will be a promising dental restorative because it demonstrated significantly improved mechanical strengths and almost no in vitro cytotoxicity as compared to current commercial light-cured glass-ionomer cements.

Acrylic Resins↗
PubMed2006

Properties of silorane-based dental resins and composites containing a stress-reducing monomer.

OBJECTIVE: To evaluate properties of silorane-based resins and composites containing a stress reducing monomer. METHODS: Resin mixtures and composites were formulated containing (a) a developmental stress reducing monomer [TOSU; Midwest Research Institute]; (b) Sil-Mix (3M-ESPE); (c) photo cationic initiator system. Standard BISGMA/TEGDMA resin (B/T) and composite (Filtek Z250) were used as controls. Polymerization volume change was measured using a NIST mercury dilatometer and polymerization stress using an Enduratec mechanical testing machine. Three point bend tests determined flexural elastic modulus, work of fracture, and ultimate strength (ADA 27; ISO 4049). Fracture toughness was measured using ASTM E399-90. Four groups of resins and composites were tested: Sil-Mix, methacrylate standard, and Sil-Mix with two addition levels of TOSU. An ANOVA was used and significant differences ranked using Student-Newman-Keuls test (alpha=0.05). RESULTS: Polymerization stress values for resins containing TOSU were significantly less than the other materials. Polymerization shrinkage values for Sil-Mix formulations were significantly less than for B/T, but were not different from each other. TOSU-containing formulations generally had somewhat lower mechanical properties values than Sil-Mix or B/T. Polymerization stress values for Sil-Mix-based composites were significantly less as compared to Z250. The 1wt.% TOSU composite had the lowest stress. No difference between composite groups was noted for fracture toughness or work of fracture. For ultimate strength, the 5wt.% TOSU formulation differed significantly from Z250. All Sil-Mix formulations had elastic modulus values significantly different from Z250. SIGNIFICANCE: The ability of TOSU to reduce polymerization stress without a proportional reduction in mechanical properties provides a basis for improvement of silorane-based composites.

Alkanes↗
PubMed2006

The biaxial flexural strength and fatigue property of Lava Y-TZP dental ceramic.

OBJECTIVES: The development of yttrium oxide partially stabilized zirconia (Y-TZP) has allowed the use of ceramic in load-bearing sites. The aim of this study was to evaluate and compare the biaxial flexural strength, hardness and fatigue life of colored and uncolored zirconia in the LAVAtrade mark system. MATERIALS AND METHODS: Eight groups (n=30) of standardized disc specimens (15mmx1.3mm) were used to examine the biaxial flexural strength (ISO 6872 standard) using a Dartec HC10 Fatigue Tester (Zwick Ltd., UK) and Vickers hardness was also measured. The uncolored, FS4, FS7 groups were also submitted to dynamic fatigue testing to produce stress-number curves. The strength reliability was analyzed using Weibull distribution. RESULTS: All groups had a mean biaxial flexural strength, hardness and Weibull modulus (m) of approximately 1100MPa, 1300HV and 9.8-12.9, respectively. One-way analysis of variance (ANOVA) showed no significant difference in biaxial flexural strength among the eight groups (p>0.05). Two-way ANOVA showed no significant differences in hardness values among groups except FS1 and FS5 which had significantly higher hardness values than FS4 and FS7 (p<0.001) and FS5 also had a higher hardness value than FS3 (p<0.05). Additionally, uncolored, FS4 and FS7 survived at 5x10(5) cycles at a stress level in the range of 60-65% of the mean biaxial flexural strength. CONCLUSION: There was no difference in flexural strength of uncolored and colored Y-TZP ceramic. The fatigue limit of uncolored, FS4 and FS7 zirconia may be defined as lying between 60 and 65% of the stress to failure.

Analysis of Variance↗
PubMed2006

The impact of modifying alumina air abrasion parameters on the fracture strength of a porcelain laminate restorative material.

OBJECTIVES: The modification of the "fit" surface of porcelain laminate veneer restorations in order to improve adhesion prior to cementation is often indiscriminate. As a consequence, the surface flaw distribution which is implicated in the probability of failure of the restoration is likely to be dramatically modified. The purpose of the current study was to examine the impact of different air abrasion surface treatments on the bi-axial flexure strength and surface roughness of a porcelain restorative material. METHODS: Sets of 30 Vitadur-Alpha dentin porcelain discs (15 mm diameter, 0.9 mm thickness) were alumina abraded with three different grades of alumina particle (25, 50 and 110 microm), utilizing two different air stream pressures (35 and 70 psi) and two distinct angles of incidence of particle delivery (45 degrees and 90 degrees ). Mean bi-axial flexure strengths, standard deviations, the associated Weibull moduli (m) and characteristic stress were determined using bi-axial flexure (ball on ring). RESULTS: A univariate general linear analysis of means revealed a significant difference between the mean bi-axial flexure strength values of the control group and those of groups subjected to alumina particle air abrasion. Further significance (P<0.05) was discovered with the impact of alumina particle size and the interaction between particle size and angle of incidence of particle delivery. The reliability of the fracture strength data generally improved when 50 microm alumina particles were used whereas discontinuities existed at lower strength values when 25 and 110 microm alumina particles were employed. CONCLUSIONS: Alumina particle air abrasion has a significant degradative effect on the bi-axial flexure strength of the porcelain disc-shaped specimens. Variation of alumina size, delivery pressure and angle of particle delivery all impacted on the degree of strength reduction and the shape of the survival probability distributions. It is suggested that alumina particle air abrasion acts to remove/modify the initial flaw distribution replacing it with flaws of differing geometry and stability. The premature failure of porcelain laminate restorations may be markedly influenced by alumina particle air abrasion depending upon the size and distribution of the crystalline phase present in different dentine porcelains materials used in construction of the restoration.

Air Abrasion, Dental↗
PubMed2007

Short glass fiber reinforced restorative composite resin with semi-inter penetrating polymer network matrix.

OBJECTIVES: The purpose of this study was to investigate the reinforcing effect of short E-glass fiber fillers on some mechanical properties of dental composite resin with interpenetrating polymer network (IPN)-polymer matrix. MATERIALS AND METHODS: Experimental composite resin was prepared by mixing short fibers (3mm in length) with a fraction of 22.5 wt% and IPN-resin 22.5 wt% with silane treated silica filler 55 wt% using high speed mixing machine. Test specimens (2 mm x 2 mm x 25 mm) and (9.5 mm x 5.5 mm x 3 mm) were made from the experimental composite (FC) and conventional particulate composite resin (control, Z250, 3M-ESPE). The test specimens (n=6) were either dry stored or water stored (37 degrees C for 30 days) before the mechanical tests. Three-point bending test was carried out according to ISO 10477 and compression loading test was carried out using a steel ball (Ø3.0mm) with speed of 1.0mm/min until fracture. Degree of monomer conversion (DC%) of both composites was determined by FTIR spectrometry. Water sorption and solubility of specimens were also measured. Scanning electron microscopy was used to evaluate the microstructure of the composite. RESULTS: ANOVA revealed that experimental fiber composite had statistically significantly higher mechanical performance of flexural strength (210 MPa) and compressive load-bearing capacity (1881 N) (p < 0.05) than control composite (111 MPa, 1031 N). Degree of conversion of the FC (59%) and conventional composite (57%) was at the same range. SIGNIFICANCE: The use of short fiber fillers with IPN-polymer matrix yielded improved mechanical performance compared to conventional restorative composite.

Absorption↗
PubMed2007

Laser-induced fluorescence to discriminate between a dental composite resin and tooth.

PURPOSE: Investigation of laser-induced fluorescence of an experimental pigment (Flu) to discriminate between a filling and the tooth and its influence on the material properties of experimental dental composites. MATERIALS AND METHODS: Three experimental composites (EC) were manufactured. The standard contained no Flu, Flu-0.5 contained 0.5%, Flu-1.0 contained 1%. To judge the extent of fluorescence, specimens and fillings placed in natural teeth were irradiated with an infrared laser (980 nm, 120 mW). Flexural strength, modulus of elasticity, depth of cure, water sorption, solubility, and color (CIE-L(*)a(*)b(*)-values) were measured to investigate the influence of Flu on EC. ANOVA was calculated and the statistical significance was p < 0.05. RESULTS: Strong laser-induced green fluorescence was observed so that fillings and tooth structures were clearly discriminated. No influence of Flu on flexural strength and modulus of elasticity occurred. Water sorption and solubility were far below the limits of EN ISO 4049. Increasing Flu concentrations revealed minor but significant reduction of depth of cure, shifts to more white and red and less yellow. SIGNIFICANCE: Flu provides laser-induced fluorescence allowing an easy discrimination between fillings and teeth. Flu did not severely influence the material properties.

Absorption↗
PubMed2005

Ligand-based assessment of factor Xa binding site flexibility via elaborate pharmacophore exploration and genetic algorithm-based QSAR modeling.

The flexibility of activated factor X (fXa) binding site was assessed employing ligand-based pharmacophor modeling combined with genetic algorithm (GA)-based QSAR modeling. Four training subsets of wide structural diversity were selected from a total of 199 direct fXa inhibitors and were employed to generate different fXa pharmacophoric hypotheses using CATALYST software over two subsequent stages. In the first stage, high quality binding models (hypotheses) were identified. However, in the second stage, these models were refined by applying variable feature weight analysis to assess the relative significance of their features in the ligand-target affinity. The binding models were validated according to their coverage (capacity as a three-dimensional (3D) database search queries) and predictive potential as three-dimensional quantitative structure-activity relationship (3D-QSAR) models. Subsequently, GA and multiple linear regression (MLR) analysis were employed to construct different QSAR models from high quality pharmacophores and explore the statistical significance of combination models in explaining bioactivity variations across 199 fXa inhibitors. Three orthogonal pharmacophoric models emerged in the optimal QSAR equation suggesting they represent three binding modes accessible to ligands in the binding pocket within fXa.

Algorithms↗
PubMed2005

Flexible versus rigid intrauterine insemination catheters: a prospective, randomized, controlled study.

OBJECTIVE: To prospectively compare pregnancy rates for couples undergoing IUI by a single healthcare provider with random assignment to either rigid (Tomcat; Kendall Sovereign, Mansfield, MA) or flexible (Soft Pass; Cook, Spencer, IN) catheters. DESIGN: Randomized, controlled study. SETTING: Tertiary care infertility practice. PATIENT(S): One hundred infertile women enrolled from a single infertility practice who met the inclusion and exclusion criteria for IUI were enrolled. Of the 100 patients, 95 underwent ovarian stimulation before IUI: 35 with clomiphene citrate alone, 60 with clomiphene citrate combined with a single dose of gonadotropins. INTERVENTION(S): Timed IUI was performed with either rigid (Tomcat) or flexible (Cook) insemination catheters. MAIN OUTCOME MEASURE(S): Pregnancy rate per cycle. RESULT(S): No differences were noted between groups for the following: age, length of infertility, day-3 FSH level, number of prior IUI cycles, total motile sperm count, days of abstinence, infertility diagnoses, insemination ratings, and stimulation protocols. No difference in pregnancy rates was observed between rigid and flexible catheter groups. CONCLUSION(S): There is no statistically significant difference between flexible and rigid catheters for IUI.

Adult↗
PubMed2006

The Cath-Cam: a new concept in colonoscopy.

BACKGROUND: Guidewires and catheters exert less force on the gut wall than an endoscope. OBJECTIVE: To develop a guidewire-assisted device for colonoscopy. METHODS: A light-weight flexible catheter illuminated with light-emitting diodes was designed to carry an ultraslim high-resolution videoendoscope of 3 mm. Tip bend stiffness was 5 times less than a colonoscope. Hinged guidewires were passed, folded, through the accessory channel. A loop could be rapidly formed to explore the lumen. RESULTS: The catheter followed curves of excised pig colon and exerted significantly less force on the colon wall than a colonoscope (mean 1.6 +/- 0.23 N vs 3.0 +/- 0.37 N, P < .05; bend-radius, 80 mm). Survival studies in pigs showed that the guidewire loop could be advanced under visual control and the Cath-Cam could be advanced by using much less force than the colonoscope. CONCLUSIONS: A catheter-based colonoscope with a miniature video imager reduced the force required for successful colonoscopy in pigs.

Animals↗
PubMed2006

Double-balloon endoscopy: from concept to reality.

The history of the double-balloon endoscope from conception to development and practical application has been described. The theory itself is quite simple, and there were opinions doubting its practicality at the early stage of development.Double-balloon endoscopes, however, are commercially available now. They have been used widely, and their usefulness has been recognized. When development of the double-balloon endoscope was progressing, development of capsule endoscopes also was progressing. The authors often heard opinions that, since capsule endoscopes were expected to become commercially available in the near future, it was out-of-date to devise a method to insert an enteroscope into the small intestine. The authors, however, believed that if the use of capsule endoscopes spread, the necessity of an enteroscope that can reach the entire area in the small intestine would not disappear, but become even bigger. If any abnormal finding is detected by a capsule endoscope, the necessity of enteroscopy for a detailed examination increases. This is being proven at present.

Catheterization↗
PubMed2005

Mechanical evaluation of mandibular defects reconstructed using osteogenic protein-1 (rhOP-1) in a sheep model: a critical analysis.

Osteoinductive bone morphogenetic proteins (BMPs) have been used extensively in experimental and clinical orthopaedic research. It is a natural progression for these growth regulators to be tested in the craniofacial region. The aim of this investigation was to analyse the mechanical properties of the sheep mandibles reconstructed using recombinant human osteogenic protein type 1 (rhOP-1). A unilateral 35 mm osteoperiosteal continuity defect was created at the parasymphyseal region of the mandible in six adult sheep. The animals were sacrificed 3 months after surgery and mechanical properties of the regenerated bone at the operated sides (OS) were compared to the corresponding bone at the non-operated side (NOS). The regenerated tissue at the OS were then submitted for histological and histomorphometric analysis. Although all the animals achieved complete bony union, a wide range of mechanical properties was found. The rhOP-1-induced bone achieved a mean of 36% of the strength of the bone at the NOS (P < 0.05). The mean value of the stiffness of the OS was 24% of the NOS (P < 0.05). While half of the samples of the OS had 'weak' mechanical properties (9-25% strength compared to NOS) and a low stiffness (6-18%), the rest showed relatively higher strength (47-63%) and were stiffer (35-47%). Unlike the NOS, the operated sides failed under tensile stresses and cracks initiated at the superior border of the mandible. The wide mechanical variations suggest that further basic bone biology research is needed to provide better understanding of the cellular and molecular events which take place during the process of osteoinduction.

Activin Receptors, Type I↗