Porous polyethylene for tissue engineering applications in diabetic rats treated with calcitonin: Histomorphometric analysis

Purpose: The purpose of this work was to study the bone tissue reaction after porous polyethylene (Polipore) implantation into surgical defects in the parietal bones of rats with streptozotocin-induced diabetes, treated with salmon calcitonin. Materials and Methods: Porous polyethylene implants were placed in bone defects created in 36 adult female rats. The rats were divided into 3 equal groups: diabetic treated with calcitonin (DCa), diabetic (D), and control (C). The animals of the DCa group received applications of salmon calcitonin on alternating days immediately after the surgery until sacrifice. The rats were sacrificed after 15, 30, 60, and 90 days, and the defects were examined histologically and statistically through histomorphometric analysis. Results: Histomorphometric analysis showed that there was no statistically significant difference in the mean quantity of inflammatory cells among all study groups after 15 and 90 days. At 30 days, a statistically significant difference was observed between the D and C groups and the D and DCa groups. At 60 days, there was no statistically significant difference between the D and DCa groups. Discussion: Porous polyethylene can be considered an option for implant material when there are investigations that prove its biocompatibility and stability in the host tissues. Salmon calcitonin positively aided the bone repair and attenuated the inflammatory response until 30 days after the surgery. Conclusion: Porous polyethylene was tolerated by the host tissues in all groups, and moderate chronic inflammatory reaction was observed up to the 90-day period. Salmon calcitonin attenuated the inflammatory response up until 30 days.

Effect of microwave treatments on dimensional accuracy of maxillary acrylic resin denture base

Microwave energy has been used as an alternative method for disinfection and sterilization of dental prostheses. This study evaluated the influence of microwave treatment on dimensional accuracy along the posterior palatal border of maxillary acrylic resin denture bases processed by water-bath curing. Thirty maxillary acrylic bases (3-mm-thick) were made on cast models with Clássico acrylic resin using routine technique. After polymerization and cooling, the sets were deflasked and the bases were stored in water for 30 days. Thereafter, the specimens were assigned to 3 groups (n=10), as follows: group I (control) was not submitted to any disinfection cycle; group II was submitted to microwave disinfection for 3 min at 500 W; and in group III microwaving was done for 10 min at 604 W. The acrylic bases were fixed on their respective casts with instant adhesive (Super Bonder®) and the base/cast sets were sectioned transversally in the posterior palatal zone. The existence of gaps between the casts and acrylic bases was assessed using a profile projector at 5 points. No statistically significant differences were observed between the control group and group II. However, group III differed statistically from the others (p<0.05). Treatment in microwave oven at 604 W for 10 min produced the greatest discrepancies in the adaptation of maxillary acrylic resin denture bases to the stone casts.

Zygomatic bone: Anatomic bases for osseointegrated implant anchorage

Purpose: The aim of the present study was to evaluate zygomatic bone thickness considering a possible relationship between this parameter and cephalic index (Cl) for better use of Cl in the implant placement technique. Materials and Methods: Cl was calculated for 60 dry Brazilian skulls. The zygo matic bones of the skulls were divided into 13 standardized sections for measurement. Bilateral measurements of zygomatic bone thickness were made on dry skulls. Results: Sections 5, 6, 8, and 9 were appropriate for implant anchorage in terms of location. The mean thicknesses of these sections were 6.05 mm for section 5, 3.15 mm for section 6, 6.13 mm for section 8, and 4.75 mm for section 9. In only 1 section, section 8, did mean thickness on 1 side of of the skull differ significantly from mean thickness on the other side (P <.001). Discussion: For the relationship between quadrant thick ness and Cl, sections 6 and 8 varied independently of Cl. Section 5 associated with brachycephaly, and section 9 associated with subbrachycephaly, presented variations in the corresponding thickness. Conclusion: Based on the results, implants should be placed in sections 5 and 8, since they presented the greatest thickness, except in brachycephalic subjects, where thickness was greatest in section 5, and in subbrachycephalic subjects, where thickness was greatest in section 9. Cl did not prove to be an appropriate parameter for evaluating zygomatic bone thickness for this sampling.

Short-term treatment effects produced by the herbst appliance in the mixed dentition

This prospective clinical investigation evaluates the dentoalveolar and skeletal cephalometric changes produced by the Herbst appliance during treatment of mixed dentition patients with Class II division 1 malocclusion. Thirty individuals (15 male and 15 female individuals; initial mean age nine years 10 months) were treated with the Herbst appliance for a period of 12 months. For comparison, the records of 30 untreated Class II children (15 boys, 15 girls; initial mean age nine years eight months) were followed without treatment for a period of 12 months. The results indicated that the treatment effects produced in the mixed dentition patients were primarily dentoalveolar in nature. The mandibular incisors were tipped labially, and the maxillary incisors were retruded; a significant increase in mandibular posterior dentoalveolar height occurred, and there was a restriction in the vertical development of the maxillary molars. There was no difference in the forward growth of the maxilla between the two groups. In comparison with the controls, however, the Herbst treatment produced a modest but statistically significant increase in total mandibular length. This increase in total mandibular length, however, was less than that observed in adolescent Herbst patients in other studies. © 2005 by The EH Angle Education and Research Foundation, Inc.

Anelastic spectroscopy in Al2O3

Engineering ceramics have found use in many applications, such as engine parts, ball bearings, artificial bone and hip replacements and gyroscopes, because of their good chemical inertness, hardness, high temperature stability and excellent wear resistance. Oxide ceramic may meet these demands. Alumina (Al2O3) ceramics offer a high potential for many engineering applications, such as wear- and/or corrosion-resistant components, and as material for substrates or housings in microelectronic devices. Alumina is used among other things for seal ring, draw-cones, guides, water mixing tapes, bearing parts, medical prostheses and cutting tools. Measurements of the elastic energy loss and modulus (anelastic spectroscopy) as a function of temperature can distinguish among the different atomic jumps, which occurs in the various phases or at different local ordering. In this paper, it is reported anelastic relaxation measurements in Al2O3 samples using commercial starch. These measurements were carried out in a torsion pendulum operating in frequencies around 40 Hz. The results shown strongly influence of the type of forming in the elastic modulus obtained by anelastic relaxation measurements.

Digital radiographic evaluation of optical density of porcelains used for fabrication of inlay/onlay prosthesis

The purpose of this article was to compare the mean value of optical density of four porcelains commonly used for fabrication of inlay/ onlay prostheses using direct digital radiograph. The sample consisted of 20 2-mm thick porcelain specimens (measured by digital pachymeter): Empress (Ivoclair), Simbios (Degussa), Vita Omega 900 and Vitadur Alpha (Vita Zahnfabrik). The values of optical density of the specimens were expressed in millimeters aluminum equivalent (mm eq Al). The samples were X-rayed using two charge coupled devices (CCD) - RVG (Trophy) - Visualix (Gendex) and a phosphor plate system - Digora (Soredex). The optical density reading was performed with Image Tool 1.28 in a total of 110 measurements. Statistical analysis showed that there were statistically significant differences in all materials studied (p < 0.05) regardless of the radiographic system used. The highest optical density value was found for Omega 900 (1.8988 mmeqAl - Visualix - Gendex) and the lowest for Vitadur Alpha (0.8647 - Visualix - Gendex). Thus, the material presenting the highest degree of optical density was Omega 900, Empress and Simbios presented intermediate optical density values, Vitadur Alpha presented the lowest value, and the optical density of porcelains was not influenced by the digital radiography systems.

Prótesis radífera: Alternativa en el tratamiento de neoplasias de cabeza y cuello

Radipherpus protheses are a means of treatment for malignant tumor-carrying patients. These protheses are used in cases of brachytherapy or external actinotherapy by contact and allow treating them with high radiation doses that are quickly released from the areas next to tumor, so that the radiations be restricted to the affected region, without the emissions damaging or destroying the soft tissues. Based on these considerations, the present paper was aimed at making literature review on the use of radipherous protheses for the treatment of head and neck neoplasias. © 2006 1995, Editorial Ciencias médicas.

Effect of disinfectants on the hardness and roughness of reline acrylic resins

Purpose: Potential effects on hardness and roughness of a necessary and effective disinfecting regimen (1% sodium hypocholorite and 4% chlorhexidine) were investigated for two hard chairside reline resins versus a heat-polymerizing denture base acrylic resin. Materials and Methods: Two standard hard chairside reliners (Kooliner and Duraliner II), one heat-treated chairside reliner (Duraliner II +10 minutes in water at 55°C), and one standard denture base material (Lucitone 550) were exposed to two disinfecting solutions (1% sodium hypochlorite; 4% chlorhexidine gluconate), and tested for two surface properties [Vickers hardness number (VHN, kg/mm2); Roughness (Ra, μm)] for different times and conditions (1 hour after production, after 48 hours at 37 ± 2°C in water, after two disinfection cycles, after 7 days in disinfection solutions, after 7 days in water only). For each experimental condition, eight specimens were made from each material. Data were analyzed by analysis of variance followed by Tukey's test, and Student's t-test (p= 0.05). Results: For Kooliner (from 6.2 ± 0.3 to 6.5 ± 0.5 VHN) and Lucitone 550 (from 16.5 ± 0.4 to 18.4 ± 1.7 VHN), no significant changes in hardness were observed either after the disinfection or after 7 days of immersion, regardless of the disinfectant solution used. For Duraliner II (from 4.0 ± 0.1 to 4.2 ± 0.1 VHN), with and without heat treatment, a small but significant increase in hardness was observed for the specimens immersed in the disinfectant solutions for 7 days (from 4.3 ± 0.2 to 4.8 ± 0.5 VHN). All materials showed no significant change in roughness (Kooliner: from 0.13 ± 0.05 to 0.48 ± 0.24 μm; Duraliner II, with and without heat treatment: from 0.15 ± 0.04 to 0.29 ± 0.07 μm; Lucitone 550: from 0.44 ± 0.19 to 0.49 ± 0.15 μm) after disinfection and after storage in water for 7 days. Conclusions: The disinfectant solutions, 1% sodium hypochlorite and 4% chlorhexidine gluconate, caused no apparent damage on hardness and roughness of the materials evaluated. Copyright © 2006 by The American College of Prosthodontists.

Influence of the facial pattern on ANB, AF-BF, and Wits appraisal.

AIM: To assess the correlation between Wits and AF-BF appraisals with the ANB angle, and verify the influence of the facial type on these appraisals. METHODS: Lateral cephalometric radiographs from 118 untreated individuals were separated into 3 groups according to the facial pattern (brachyfacial, mesofacial, and dolichofacial). The radiographs were digitized and submitted to ANB angle and Wits and AF-BF appraisals on computer software. All radiographs were retraced for intraobserver and interobserver error tests. RESULTS: The Student's t test demonstrated no statistically significant differences on the intraobserver's test (P > .05). There were statistically significant differences in the readings of Wits values of the 3 groups and for AF-BF values in the brachyfacial and mesofacial groups (P <.05). The multiple linear regression tests demonstrated high correlation between ANB and AF-BF for the 3 groups (r2, 0.768). The same result was found for ANB and Wits (r2, 0.624). CONCLUSION: Facial pattern does not have an influence on the correlation between ANB and AF-BF nor between ANB and Wits, but it does influence the measurements of ANB, AF-BF, and Wits.

Degree of conversion and molecular weight of one denture base and three reline resins submitted post-polymerization treatments

The effect of post-polymerization treatments (MW-microwave irradiatron and WB-water-bath) on the degree of conversion (DC) of three reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and one denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long), was evaluated by using FT-Raman spectroscopy (n = 5). The molecular weight (Mw) of the powder of all materials and of K polymerized specimens (control; MW; and WB; n = 3) was analyzed using GPC. DC data were analyzed using Kruskal-Wallis test (α = .05). For control specimens, there were no significant differences between U (68%) and LL (77%) and among LL, K (81%), and T (84%). LS (92%) had the highest DC (P<0.05). Only material K exhibited an increased DC after WB (P<0.05). All powders had Mw from 4.0 × 105 to 6.5 × 105 and narrow Mw distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with Mw similar to that of K powder.

Comparative Analysis of 2 Techniques of Double-Gloving Protection During Arch Bar Placement for Intermaxillary Fixation

Purpose: This study was conducted to comparatively evaluate, in a prospective and randomized manner, 2 techniques for providing double-gloving protection during arch bar placement for intermaxillary fixation. Materials and Methods: A total of 42 consecutive patients in whom application of an Erich bar was indicated for intermaxillary fixation were equally divided into 2 groups. In group 1, 2 sterile surgical gloves were used; in group 2, a nonsterile disposable inner glove was used under a sterile surgical glove. Wilcoxon, Mann-Whitney, Kruskal-Wallis, and binomial statistical tests were used to analyze the findings. Results: A total of 103 perforations were found in the outer gloves (47 in group 1 and 56 in group 2), along with 5 perforations in inner gloves in both groups (α = .01). No significant statistical difference was found between groups in terms of inner glove perforations (α = .05). The nondominant hand presented with 70.9% of the perforations, statistically significant to 1%. Conclusions: Both double-gloving techniques were found to provide effective clinician protection. The use of a nonsterile disposable glove under the surgical glove is possible for less-invasive procedures, offering the same safety as using 2 sterile surgical gloves while decreasing operational costs. This method does not eliminate the need to change gloves when a perforation is suspected or noted during the surgery, however. © 2007 American Association of Oral and Maxillofacial Surgeons.

Homogenous demineralized dentin matrix for application in cranioplasty of rabbits with alloxan-induced diabetes: Histomorphometric analysis

Purpose: The aim of this work was to evaluate the bone-repair process after implantation of homogenous demineralized dentin matrix (HDDM) slices in surgical defects created in the parietal bones of rabbits with alloxan-induced diabetes. Materials and Methods: Forty-eight rabbits were selected and divided into 4 groups of 12 rabbits: the control group, diabetic rabbits (D), diabetic rabbits with a PTFE barrier (D-PTFE), and diabetic rabbits with a PTFE barrier and with slices of homogenous demineralized dentin matrix (D-PTFE+HDDM). The diabetic animals received a single dose of alloxan monohydrate (90 mg/kg) intravenously on the marginal ear vein, and their blood glucose was verified daily. The rabbits were sacrificed after 15, 30, 60, and 90 days. The histologic findings show both better bone structure and significantly greater bone density, as determined by histomorphometric analysis, for the D-PTFE + HDDM group than for the other 3 groups (P < .01). It was also observed that the mean bone density increased gradually from 15 to 90 days (except in the D-PTFE group). Conclusion: It was concluded that the HDDM was biocompatible with the bone repair of diabetic rabbits and that HDDM slices stimulated bone tissue formation. Facilitation of bone repair with HDDM could be useful in diabetic patients.

Methanol oxidation on PtRu/C electrocatalysts prepared by a microemulsion method

PtRu/C nanocatalysts were prepared by a microemulsion method using different values of water/surfactant molar ratio in order to get different particle sizes. Crystallite sizes and structural properties were determined by X-ray diffraction. Particle size and distribution were characterized by transmission electron microscopy and average composition was determined by energy dispersive X-ray analysis. Differential scanning calorimetry measurements indicated the presence of oxides in the as-prepared catalysts. The general electrochemical behavior was evaluated by cyclic voltammetry in 0.5 M sulfuric acid and the electrocatalytic activity towards the oxidation of methanol was studied in 0.5 M methanol acid solutions by potential sweeps and chronoamperometry. copyright The Electrochemical Society.

Reconstruction of Mandibular Segmental Defects Using the Guided-Bone Regeneration Technique With Polylactide Membranes and/or Autogenous Bone Graft: A Preliminary Study on the Influence of Membrane Permeability

Purpose: Bone maintenance after mandibular reconstruction with autogenous iliac crest may be disappointing due to extensive resorption in the long term. The potential of the guided-bone regeneration (GBR) technique to enhance the healing process in segmental defects lacks comprehensive scientific documentation. This study aimed to investigate the influence of polylactide membrane permeability on the fate of iliac bone graft (BG) used to treat mandibular segmental defects. Materials and Methods: Unilateral 10-mm-wide segmental defects were created through the mandibles of 34 mongrel dogs. All defects were mechanically stabilized, and the animals were divided into 6 treatment groups: control, BG alone, microporous membrane (poly L/DL-lactide 80/20%) (Mi); Mi plus BG; microporous laser-perforated (15 cm2 ratio) membrane (Mip), and Mip plus BG. Calcein fluorochrome was injected intravenously at 3 months, and animal euthanasia was carried out at 6 months postoperatively. Results: Histomorphometry showed that BG protected by Mip was consistently related to larger amounts of bone compared with other groups (P ≤ .0001). No difference was found between defects treated with Mip alone and BG alone. Mi alone rendered the least bone area and reduced the amount of grafted bone to control levels. Data from bone labeling indicated that the bone formation process was incipient in the BG group at 3 months postoperatively regardless of whether or not it was covered by membrane. In contrast, GBR with Mip tended to enhance bone formation activity at 3 months. Conclusions: The use of Mip alone could be a useful alternative to BG. The combination of Mip membrane and BG efficiently delivered increased bone amounts in segmental defects compared with other treatment modalities. © 2008 American Association of Oral and Maxillofacial Surgeons.

Polyethylene gel in the subcutaneous tissue of rats: Histopathologic and systemic evaluation

Purpose: To evaluate the histological and systemic response to subcutaneous injection of polyethylene gel in rats. Methods: Twenty-one white male rats were divided into 3 groups (G): G1 and G2 received subcutaneous polyethylene gel injection in the dorsal midline and were sacrificed at 30 and 60 postoperative days, respectively. G3 was not exposed to the polyethylene gel and was sacrificed after 60 days. Blood levels of lactate dehydrogenase (LDH), creatine kinase (CK), and alkaline phosphatase (ALP) were evaluated. The heart, kidney, liver, adrenal gland, injection site, and adjacent tissues were histologically examined. The results were submitted to statistical analysis. Results: There was no clinical evidence of extrusion, reduction of the injected volume, or abnormalities in the adjacent tissues. Blood levels of CK and LDH were normal and similar in all groups. ALP levels were significantly lower in G2 than in G1 and G3. The systemic organs were normal on histological examination in the 3 groups evaluated. Microscopically, the polyethylene gel was surrounded by a thin pseudocapsule formation and minimal inflammatory cell response, which decreased from G1 to G2. Conclusion: The subcutaneous injection of polyethylene gel in rats elicited minimal local inflammatory response and no systemic side effects. Copyright © 2008 Informa Healthcare USA, Inc.