Rubber Base Research Articles

Evaluation and Comparison of the Effect of Different Border Molding Materials on Complete Denture Retention: An in vivo Study

Different border molding materials have different qualities which help in recording fine details of tissues. The present study was conducted to evaluate and compare the effect of different border molding materials on complete denture retention. The present study was conducted on 10 completely edentulous patients in the age group of 50 to 70 years. On each patient, three different border moldings were completed. In group I, border molding was done with green stick impression compound. In group II, border molding was done with putty consistency addition silicone. In group III, border molding and final impression were done by polyether impression material in a single step. Permanent denture bases were fabricated with wire loop at the center. Retention was assessed in all three groups using a digital force gauge. Upon data compilation and preparation of spread sheets for concerned groups, it was subjected to statistical analysis using Statistical Package for the Social Sciences (SPSS) software version 21.0 for Windows. Mean age ± standard deviation (SD) was 57.40 ± 8.46 in group I, 57.40 ± 8.46 in group II, and 57.40 ± 8.46 in group III. The difference was nonsignificant (p > 0.05). The overall mean value for the group I was 4.59 ± 0.81. For group II, it was 4.7 ± 0.81. For group III, it was 6.72 ± 0.81. The difference was significant (p < 0.05). Green stick compound with light body final wash showed the lowest mean values of complete denture retention. Dentures made using polyether final impression material showed the highest mean values of complete denture retention followed by putty rubber base border molding with light body final wash. In this study, polyether showed the highest mean retentive value compared with other tested materials; therefore, it could possibly provide some future innovative means in achieving optimal denture retention.

Study of salivary arecoline in areca nut chewers.

Aims:Arecoline, a predominant alkaloid present in arecanut, has been implicated in the pathogenesis of several oral diseases because of its mutagenic and carcinogenic potential. The response of cultured cells to arecoline is highly dependent on its concentration; arecoline stimulates cultured cells above 0.1 μg/ml and is cytotoxic above 10 μg/ ml. Although this alkaloid seems important for areca nut induced oral diseases and carcinogenesis, little is known of the levels achieved before, during and after chewing. Also, it is prudent to understand its effects in arecanut chewers for a comprehensive understanding of its pathogenesis. Accordingly, the present study quantified the salivary arecoline levels in arecanut chewers.Materials and Methods:The study participants were divided into Study Group A & B and Control Group C; unstimulated whole saliva was collected by spitting method for a period of 5 min. Then, participants in Group A and C chewed 0.5 g of areca nut without any other additives while in Group B were asked to chew 0.5 g of inert rubber base impression material. Stimulated whole saliva from all three groups was collected into graduated tubes during chewing at time intervals of 1, 3, 5, 10, 15, 20 and 25 min. Then, all participants were asked to remove nut particles or inert rubber base material from the mouth, and saliva samples were collected further up to 20 min, changing tubes at 5 min interval. Salivary arecoline was quantitated by HPLC-MS. The tabulation and descriptive statistics of the study were carried out.Results:In the present study, baseline levels of arecoline were zero in all three groups, whereas mean salivary arecoline levels during chewing were 76.93 ng/ml, 129.83 ng/ml and 64.83 ng/ml and after chewing were 196.17 ng/ml, 321.12 ng/ml and 43.75 ng/ml in Groups A, B and Control respectively, which were significantly higher than reported threshold levels.Conclusions:The data from this study reveals that a significant amount of arecoline would be trapped in oral cavity, or being re-circulated between blood and saliva might have resulted in surprisingly high levels of arecoline even 10 mins after chewing in both groups after which the levels started declining. The higher levels of salivary arecoline achieved during and after chewing are enough to cause cytotoxic and genotoxic effects on oral tissues over a period of time in chronic chewers. The great differences in salivary arecoline levels achieved during chewing, may contribute to the variable response to areca nut seen in communities where this habit is widespread. Areca nut users have persistent background salivary arecoline levels long after chewing, whereas concentrations achieved are highly variable and consistent with a role in oral pre-malignancy and malignancy..

Analysis of a Frame-Shear Wall Concrete Structure by Using Base Isolation and Evaluation of Structure-Soil Interaction

A base isolation system is a type of earthquake-resistant structure design approach based on the principle of reducing a structure’s earthquake response rather than increasing the structure’s earthquake resistance capacity. Seismic base isolated structures have the ability to make large displacements relative to the level of insulation elements. This means that a large structure performs very small displacements between floors during an earthquake and exhibits a rigid body behavior. At this point, the earthquake forces acting on the structure decrease along with the floors. In this article a school building composed of frame-shear wall is resolved primarily with the traditional fixed base structure system, mode shapes are found and periods are obtained. For earthquake response analysis, earthquake loads are distributed to the floors using the equivalent seismic load method and structural elements experiencing capacity problems are found. Then, using the earthquake record, larger failure of cross sections and capacity problems are obtained compared to the first method. In the second stage, the same structure is dissolved again by placing the lead core rubber base isolators between the base and the vertical structural members. The periods of structures under earthquake load have increased significantly by utilizing base isolation, as a result of that spectral accelerations decreased. Thus, large decreases in the shear forces acting to the structure are determined and failures of cross sections are removed.

3 ラバーベース印象に対するジメチルポリシロキサン(シリコナイズL-25)の効果について (第440回 大阪歯科学会例会)

3 ラバーベース印象に対するジメチルポリシロキサン(シリコナイズL-25)の効果について (第440回 大阪歯科学会例会)

Skin permeability of tulobuterol in two transdermal formulations and their followability

Various generic transdermal formulations of tulobuterol containing rubber and acrylate base polymers are commercially available in Japan. However, none of the formulations have been compared directly with respect to the skin permeability of tulobuterol and to their follow ability. Tulobuterol Tape Sawai of rubber base and Tulobuterol Tape NP of acrylate base were used to conduct the in vitro 24-hour skin permeability test of tulobuterol at receiver solution temperatures of 32°C, 37°C, and 40°C. Furthermore, the followability of these tapes were examined by measuring the depth of the pores that were formed in their adhesive layer. Consequently, the maximum flux of tulobuterol was greater for Tulobuterol Tape NP. Arrhenius plot analysis revealed that Tulobuterol Tape Sawai was more sensitive to skin surface temperature compared with Tulobuterol Tape NP. Skin abrasion had a greater effect on the skin permeability of tulobuterol in Tulobuterol Tape Sawai than in Tulobuterol Tape NP. Followability was greater for Tulobuterol Tape NP than for Tulobuterol Tape Sawai. These results suggest that a transdermal formulation of acrylate base is preferable to that with a rubber base when skin surface temperature varies or when the skin is abraded. In clinical settings, therefore, a formulation of acrylate base is preferable to a formulation of rubber base when skin surface temperature varies or when the skin is abraded. The formulation needs to be applied to the skin of less asperity for the achievement of better transdermal absorption of tulobuterol.

Fabrication of cast post and core by a modified indirect procedure and postcementation using a novel technique

The restoration of endodontically treated pulpless teeth is a challenging dental procedure. Post and core is indicated in cases of extensive coronal tooth destruction where additional retention is required. The post is used to retain a core that can be used to retain definitive prosthesis. The choice between using a cast post and a prefabricated post depends on multiple factors such as canal configuration and remaining tooth structure. It has been said that if a canal requires extensive preparation, a well-adapted cast post and core will be more retentive than a prefabricated post that does not match the canal configuration. The cast post and core is fitted to the prepared root canal space and designed to resist torsional forces. However, one drawback of cast post is its tedious and time-consuming wax pattern technique. In this case report, we have used a time saving modified indirect technique for fabricating cast post and core, without the use of any reinforcement, no wax, no pattern resin but only rubber base impression material along with a novel technique of cementation, which utilizes a modified syringe with needle to facilitate even distribution of luting cement within the canal.

Use of the standing wave method to study seismically insulated buildings

The use of the standing wave method to study seismically insulated buildings is substantiated. For two buildings of interest with different types of seismic protection (a “flexible” floor and rubber base insulators), the total field of standing waves is studied in detail. Effects that raise doubts about the reliability of seismic protection are found. Estimation of the role of nonlinear vibrations in standing waves has made it possible to establish that weak nonlinearity is recorded at high-frequency modes at small vibration amplitudes, due to discordant vibrations of the building components. The data obtained by the standing wave method are recommended for verifying models used to calculate seismic insulation of buildings.

Correlation of vermilion symmetry to alveolar cleft defect in unilateral cleft lip repair

Asymmetry is a major problem in repaired unilateral cleft lip (UCL). One of the important manifestations of this is the asymmetry of the vermilion. The aim of this study was to correlate the severity of the asymmetry in the vermilion to the size of the alveolar defect. Twenty patients aged between 6 and 18 months with complete unilateral cleft lip, alveolus, and palate were included. An impression of each patient's alveolus at the time of cheiloplasty was taken using silicon rubber base material, and a study cast was prepared. The width of the cleft alveolus was measured on these casts using a transparent grid. Frontal photographs were taken at 6 months postoperative and vermilion symmetry was measured as the ratio between the cleft and non-cleft sides. The results obtained in this study showed a direct correlation between the size of the alveolar defect and the vermilion symmetry in repaired UCL. The wider the cleft alveolus and greater the antero-posterior discrepancy, the greater is the vermilion asymmetry. The asymmetry of the vermilion in UCL after repair is directly dependent on the size of the alveolar defect. The alveolar discrepancy causes ‘in-rolling’ of the vermilion on the cleft side and affects the vermilion symmetry.

CANAL TRANSPORTATION AND CENTRIC ABILITY OF FOUR DIFFERENT NITI ROTARY SYSTEMS IN CURVED CANALS

aim: to study canal transportation and centric ability of four different NiTi rotary systems in curved canals. materials and methods: forty extracted mandibular first molars with similar length and root curvature were selected. All teeth were accessed and working length determined. Teeth were embedded in heavy body rubber base impression material after cutting of distal root to the cervical level. The teeth were randomly assigned to four groups, ten for each. Group I was prepared with ProTaper universal up to F2, group II was prepared with ProTaper Next up to X2, group III was prepared with WaveOne up to primary file, and group IV was prepared with Wave One Gold up to primary file. All teeth were submitted to Pre and post instrumentation scanning with multislice CT and root cross-sections were saved and compared at three levels; 3 mm from the apex (apical), 3mm from the canal orifice (coronal), and mid way between the two measurements (middle). Canal transportation and centric ability were estimated and statistically analyzed. Results: there was no significant difference between the four groups in apical and coronal levels, but, in middle part, there was a significant difference between them regarding canal transportation and centric ability. Conclusion: the WaveOne Gold NiTi primary reciprocating file maintained the original canal anatomy with less modification of the canal curvature compared with other file systems up to apical size 25.

Push Over Analysis of Plan Irregular Reinforced Concrete Buildings with and without a Lead Rubber Base Isolator

Push Over Analysis of Plan Irregular Reinforced Concrete Buildings with and without a Lead Rubber Base Isolator

A facile prestrain-stick-release assembly of stretchable supercapacitors based on highly stretchable and sticky hydrogel electrolyte

A facile prestrain-stick-release assembly strategy for the stretchable supercapacitor device is developed based on a novel Na2SO4-aPUA/PAAM hydrogel electrolyte, saving the stretchable rubber base conventionally used. The Na2SO4-aPUA/PAAM hydrogel electrolyte exhibits high stretchability (>1000%), electrical conductivity (0.036 S cm−1) and stickiness. Due to the unique features of the hydrogel electrolyte, the carbon nanotube@MnO2 film electrodes can be firmly stuck to two sides of the prestrained hydrogel electrolyte. Then, by releasing the hydrogel electrolyte, homogenous buckles are formed for the film electrodes to get a full stretchable supercapacitor device. Besides, the high stickiness of the hydrogel electrolyte ensures its strong adhesion with the film electrodes, facilitating ion and electronic transfer of the supercapacitor. As a result, excellent electrochemical performance is achieved with the specific capacitance of 478.6 mF cm−2 at 0.5 mA cm−2 (corresponding to 201.1 F g−1) and capacitance retention of 91.5% after 3000 charging–discharging cycles under 150% strain, which is the best for the stretchable supercapacitors.

EFFICIENT DESIGN IN BUILDING CONSTRUCTION WITH RUBBER BEARING IN MEDIUM RISK SEISMICITY: CASE STUDY AND ASSESSMENT

Earthquakes pose tremendous threats to life, property and a country's economy, not least due to their capability of destroying buildings and causing enormous structural damage. The hazard from ground excitations should be properly assessed to mitigate their action on building structures. This study is concerned with medium risk seismic regions. Specifically, the heavily populated capital city Dhaka in Bangladesh has been considered. Recent earthquakes that occurred inside and very close to the city have manifested the city's earthquake sources and vulnerability. Micro-seismicity data supports the existence of at least four earthquake source points in and around Dhaka. The effects of the earthquakes on buildings are studied for this region. Rubber base isolation is selected as an innovative option to lessen seismic loads on buildings. Case studies have been carried out for fixed and isolated based multi-storey buildings. Lead rubber bearing and high damping rubber bearing have been designed and incorporated in building bases. Structural response behaviours have been evaluated through static and dynamic analyses. For the probable severe earthquake, rubber bearing isolation can be a suitable alternative as it mitigates seismic effects, reduces structural responses and provides structural and economic benefits.

Microstructure and Temperature Characterization of Compound Crumb Rubber Modified Asphalt

Compound Crumb Rubber Modified Asphalt (CCRMA) is a mixture of waste rubber tire powder, SBS modifier and asphalt in order to modify the characteristics of asphalt. The application of using crumb rubber powder in making CCRMA is important in improvement of working characteristics of asphalt as well as in pollution control and environment protection. CCRMA, crumb rubber particles, SBS modifier and base asphalt have been examined by Scanning Electron Microscope (SEM) to observe the microcosmic appearance and the characteristic distribution of crumb rubber particles and SBS modifier in asphalt. The rotary viscometer test and dynamic shear test of CCRMA were carried out by rotational viscometer and Dynamic Shear Rheology (DSR). The influences of rubber powder content and reaction time to viscosity of CCRMA have been studied. In the stage of current study, complex modulus and phase angle of CCRMA are parameters reflecting viscoelasticity, the relation between them and temperature are researched.

Evaluation of Thermoplastic Resin as a New Pattern Material for Posts: Dimensional Accuracy and Detail Reproduction

Traditionally, dark-cure (cold-cure) acrylic resin is used as pattern material for cast post and core. A new post system that incorporates a specially designed plastic support rod and a thermoplastic resin has been introduced to the market and is claimed to simplify the procedure for cast posts fabrication. The aim of the present work was to evaluate the dimensional accuracy and detail reproduction of thermoplastic resin when used as pattern or impression material for posts, and the amount of solid residue after ignition when used as pattern material. Materials used were thermoplastic resin (Trigger Feed, Glue Gun, China), polyether rubber base material (Permadyne, ESPE), and Duralay acrylic resin (Relience Dental Manufacturing Co). A machined cut circular stainless steel (st.st) mold similar to those described in ADA specification No. 19 and BS 4269 was constructed with two horizontal and three vertical sharp line grooves. The scribed horizontal lines were used to measure the dimensional changes. The scribed vertical lines provided a measure of surface detail reproduction. A ring of 5 mm thickness was machined cut that placed on the circular st.st. mold shoulder leaving 2 mm thickness for the impression material. Thirty impressions of st. st. die were made, ten from each material used in the study. Three readings were made for each impression disc to the nearest 0.001 mm using a travelling microscope (Unitron Bi5-3174) at ×10 magnification. The percentage of dimensional change was calculated. Surface detail reproduction was evaluated, by inspecting each vertical line under a travelling microscope (Unitron Bi5-3174) at X 10 magnification using low-angle illumination. The reproduction was considered acceptable if two of three of the vertical lines were reproduced continuously and well defined for the full length. Two grams of thermoplastic resin and two grams of cold cure resin were ignited separately in porcelain crucible at 700 °C. The nonvolatile residue left was weight using electronic balance. Results of the study showed that there was no statistically significant difference in surface detail reproduction as well as dimensional stability during hardening between thermoplastic resin, cold-cure resin pattern material or polyether elastomeric impression material. There was no statistical significant difference in the percentages of solid residue left after burning out of thermoplastic resin or cold cure resin. Clinical relevance: Thermoplastic resin is a cheap, low cost, easily manipulated, elastic material, and as accurate and dimensionally stable as the rigid cold cure resin pattern. Hence, it must replace the traditional post-core pattern materials or impression materials for post hole(s).

Modeling of a new semi-active/passive magnetorheological elastomer isolator

This paper presents theoretical modeling of a new magnetorheological elastomer (MRE) base isolator and its performance for vibration control. The elastomeric element of the traditional steel–rubber base isolator is modified to a composite layer of passive elastomer and MRE which makes the isolator controllable with respect to its stiffness and damping. The proposed variable stiffness and damping isolator (VSDI) is designed based on an optimized magnetic field passing through MRE layers to achieve maximum changes in mechanical properties. The controllability of the VSDI is investigated experimentally under double lap shear tests. A model employing the Bouc–Wen hysteresis element is proposed to characterize the force–displacement relationship of the VSDI. An integrated system which consists of four VSDIs is designed, built and tested. Dynamic testing on the integrated system is performed to investigate the effectiveness of the VSDIs for vibration control. Experimental results show significant shift in natural frequency, when VSDIs are activated and the possibility of using the VSDIs as a controllable base isolator.

Features of the Thermal Degradation of Reprecipitated Polybutadienes under the Influence of a Mixture of C50-C92 Fullerenes

An investigation was made of the mechanism of physicochemical interaction of a mixture of C50-C92 fullerenes with diene rubbers. In view of their similarity, experimental data obtained by IR spectroscopy were processed on the basis of a chemometric approach to describing the results. Very small changes in the optical density of the characteristic groups of the rubbers were analysed. To extract hidden information concerning the chemical interactions of the fullerene mixture with the rubber base from the files of experimental data, discriminant analysis was used. The effect of fullerenes on macromolecules of the investigated rubbers was shown. The groups of rubbers capable of interacting with the introduced modifier were determined. It was established that the interaction of the fullerene mixture with the rubber proceeds by unconjugated double bonds.

Amalgam Inlay- An Innovative Technique

Dental amalgam is the most thoroughly researched and tested restorative material, which has been used successfully in dentistry for more than a century. Despite its poor esthetic and lack of adhesion, it is still one of the most widely used restorative materials in dental practice. This case report describes a novel clinical technique of fabricating an inlay using silver amalgam for restoring a large cervical abrasion cavity. A patient with large and deep cervical abrasion cavity in relation to mandibular right posterior region was reported. The impression of the abrasive cavity was done using rubber base impression material. Later, cast was fabricated, amalgam was condensed into the cavity, contoured and inlay was prepared. Fit of the inlay was checked on the patient, thereafter it was finished and polished and cemented using luting glass ionomer cement.

Seismic Evaluation of Base Isolated System Equipped with Shape Memory Alloys

Seismic isolation system is an example of passive control system that effectively improves the performance of structures. This research discusses the seismic performance of a elastomeric base isolation system which provide the combined features of vertical load support, horizontal flexibility and energy absorbing capacity, utilizing shape memory alloys that provides re-centering force and additional damping in the system. Also this paper compares the effect of such alloys with memory effect and/or superelasticity (with pre-straining) in base isolated structure. To provide such comparison, a nonlinear structural model has been developed on some benchmark control problems and some health monitoring evaluation criterias are used. The smart base isolation utilizes the different responses of shape memory alloys at several levels of strain to control the displacements of the rubber bearing and base shear at excitation level. Furthermore the proposed based isolation systems has enhanced performance in terms of response reduction and re-centering capacity.

Dimensional accuracy of two rubber base impression materials as a function of spacer design and techniques in custom trays for fixed partial dentures

BackgroundA prostheses can't be better than the cast over which it has been fabricated. To make accurate casts, accurate impressions are mandatory. To get an accurate and dimensionally stable impression, various techniques and materials have been advocated. This study compares the most commonly used techniques and materials for dimensional accuracy. Two types of spacers were designed to compare the addition silicon and polyether and their techniques. MethodsA metal die was used to make the impressions. A total of 60 impressions were made using multiple mix and monophasic techniques for addition silicon and polyether in custom trays. A travelling microscope was used to measure the dimensional accuracy of die stone casts retrieved from impressions. ResultsThe results were compared using paired t test and SPSS software. The study was highly significant (p < 0.001). The polyether was more accurate than the addition silicon and spacer design I (adapted to the edentulous area) was more accurate than the design II (spacer over the abutments, not adapted to edentulous area). The multiple mix technique was more accurate than the monophasic for addition silicon. ConclusionThe combination of multiple mix technique with spacer design I for addition silicon gave the best accurate results.

Full‐scale shaking table test of a base‐isolated medical facility subjected to vertical motions

SUMMARYBase isolation is a well known technology that has been proven to reduce structural response to horizontal ground accelerations. However, vertical response still remains a topic of concern for base‐isolated buildings, perhaps more so than in fixed‐base buildings as isolation is often used when high performance is required. To investigate the effects of vertical response on building contents and nonstructural components, a series of full‐scale shaking table tests were conducted at the E‐Defense facility in Japan. A four‐story base‐isolated reinforced concrete building was outfitted as a medical facility with a wide variety of contents, and the behavior of the contents was observed. The rubber base isolation system was found to significantly amplify vertical accelerations in some cases. However, the damage caused by the vertical ground motions was not detrimental when peak vertical floor accelerations remained below 2 g with three exceptions: (1) small items placed on shelves slid or toppled; (2) objects jumped when placed on nonrigid furniture, which tended to increase the response; and (3) equipment with vertical eccentricities rocked and jumped. In these tests, all equipment and nonstructural components remained functional after shaking. Copyright © 2013 John Wiley &amp; Sons, Ltd.