Irreversible Hydrocolloid Research Articles

Efficacy of Various Disinfectants on Dental Impression Materials

Aim: Dental impressions often carry microorganisms that may cause cross infection from patients to dental staff. This in-vivo study evaluated microbial load on impressions (dentulous and edentulous) and the effectiveness of various disinfectants on the reduction of microorganisms from the impression surfaces after immersion and spray disinfection of impressions using five disinfectants for 10 minutes time. Materials and Methods: A total of 30 edentulous and 30 dentulous impressions were made using zinc oxide Eugenol and irreversible hydrocolloid respectively. Disinfectants used were Povidine-Iodine, Sodium Hypochlorite, Glutaraldehyde, Peracetic Acid (as immersion) and Isopropyl Alcohol (as spray). Results: The microbial load on irreversible hydrocolloid impression (dentulous subjects) was observed to be twice than that on the zinc oxide Euginol impression (edentulous subjects). All disinfectants showed reduction in microbial growth. Conclusions: Peracetic Acid was found most effective followed by Glutaraldehyde and Sodium Hypochlorite; the latter disinfectants were comparable in their antimicrobial effect. Povidine-Iodine and Isopropyl Alcohol were found to be less effective than Peracetic Acid, Glutaraldehyde and Sodium Hypochlorite, but were effective than the control group. Disinfection of impression materials should be mandatory to prevent cross-infection.

A Microbiologic Investigation Following the Disinfection of Irreversible Hydrocolloid Materials Using the Spray Method

Antimicrobial efficacy of three spray disinfectants--0.525 percent sodium hypochlorite (bleach), deconex and Sanosil--was evaluated on contaminated alginate disks. Disks were sprayed eight to 10 times after rinsing in water for 15 seconds. The samples were then placed into plastic bags containing a sterile moist cotton roll for 10 minutes. The use of 0.525 percent sodium hypochlorite sprayed onto the surface of alginate effectively disinfected 96.6 percent of the samples.

Avaliação Dimensional de Moldes de Hidrocolóide Irreversível Após Desinfecção

The objective of this study is to evaluate if the disinfection with sodium hypochlorite affects alginate molds dimensionally. From a standard model (control group-1) confectioned with 2 prosthetic components for implantation (System INP, Mod.: Standard Diameter. 6 x 3) fixed in a base of resin ( Classic , Brazilian Industry), 14 molds (n=07) of irreversible hydrocolloid (type II, Jeltrate/Dentsply) were confectioned, of which were submitted under 2 experimental conditions: G2) one group was rinsed in current water for 15 seconds and immediately filled with special plaster type IV Dent-Mix/Asfer; G3) the other was rinsed in current water for 15 seconds and sprayed with a solution of sodium hypochlorite 0.5% (Asfer, Industry and I deal Ltda), conditioned in a closed plastic bag for 10 minutes, rinsed in plastered water and filled with special plaster. After 1 hour, molds and models were separated. With the assistance of a digital paquimeter (centesimal No PA - 04, MITUTOYO) an operator carried out the measurement between the distal points of the components of all groups. The results were analyzed by Anova under 2 criteria test of Tukey with a reliable interval of 95%. When evaluating the results, we can conclude that, the practice of disinfecting by spraying with sodium hypochlorite solution of 0.5% for 10 minutes did not influence the dimensional stability of the molds of hydrocolloid irreversible.

Influence of Matrix Type on Surface Roughness of Three Resins for Provisional Crowns and Fixed Partial Dentures

This study evaluated the effect of matrix type on the surface roughness of resins for provisional crowns and fixed partial dentures. Ninety specimens of two acrylic resins (Trim II, Tab2000) and one bis-acryl composite (Protemp II Garant) were fabricated using one of three matrices: irreversible hydrocolloid (Cavex CA37), poly(vinyl siloxane) (Aquasil) or vacuum-formed matrix (Bio-flow Hard). The sample size for each resin-matrix combination was 10. The vestibular face of one natural maxillary central incisor was used as a model to fabricate all the specimens, following the custom fabrication technique. The average roughness measurements, Ra (mum), were obtained using a profilometer, and the data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests. The results were contrasted against the surface roughness of the tooth using a one-sample t-test. Aquasil and vacuum-formed matrix had a smoother surface than Cavex CA37 regardless of the resin tested (p < 0.05). Protemp II Garant had the smoothest surface regardless of the matrix used, with no significant differences when polymerized against the three different matrices. Trim II polymerized against Cavex CA37 had a rougher (p < 0.05) surface than Aquasil or vacuum-formed matrix. Tab2000 had the smoothest surface (p < 0.05) when polymerized against a vacuum-formed matrix. There is no universal matrix that produces the smoothest surface: this depends on the compatibility between the resin and the matrix. Protemp II Garant polymerized against Cavex CA37 matrix yields a surface that is smooth enough not to require polishing unless this surface is adjusted.

Comparative study of intermaxillary relationships of manual and swallowing methods

This study compared the mandibular displacement from three methods of centric relation record using an anterior jig associated with (A) chin point guidance, (B) swallowing (control group) and (C) bimanual manipulation. Ten patients aged 25-39 years were selected if they met the following inclusion criteria: complete dentition (up to the second molars), Angle class I and absence of signs and symptoms of temporomandibular disorders and diagnostic casts showing stability in the maximum intercuspation (MI) position. Impressions of maxillary and mandibular arches were made with an irreversible hydrocolloid impression material. Master casts of each patient were obtained, mounted on a microscope table in MI as a reference position and 5 records of each method were made per patient. The mandibular casts were then repositioned with records interposed and new measurements were obtained. The difference between the two readings allowed measuring the displacement of the mandible in the anteroposterior and lateral axes. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. There was no statistically significant differences (p>0.05) among the three methods for measuring lateral displacement (A=0.38 +/- 0.26, B=0.32 +/- 0.25 and C=0.32 +/- 0.23). For the anteroposterior displacement (A=2.76 +/- 1.43, B=2.46 +/- 1.48 and C=2.97 +/- 1.51), the swallowing method (B) differed significantly from the others (p<0.05), but no significant difference (p>0.05) was found between chin point guidance (A) and bimanual manipulation (C). In conclusion, the swallowing method produced smaller mandibular posterior displacement than the other methods.

Retention strength of impression materials to a tray material using different adhesive methods: An in vitro study

A new self-stick adhesive system has been purported to eliminate the need to use chemical adhesives with plastic impression trays; however, no testing has confirmed the claim. The purpose of this study was to compare the in vitro retentive strength of impression materials to plastic substrates having conventional adhesive (CA) or the self-stick adhesive system, with and without mechanical retention. Three types of impression materials (irreversible hydrocolloid (IH), vinyl polysiloxane (VPS), and polyether (PE)) were applied to polystyrene disc-shaped surfaces (33.68 cm(2)) that were held on the arms of a universal testing machine. The appropriate CA or the self-stick adhesive system (Self-Stick Dots) (SSD) was applied to the plates, which had either no mechanical retention, or equally spaced mechanical perforations (n=4). An in vivo pilot test determined the appropriate rate of plate separation. Plates with impression material were lowered to provide 4 mm of space, the material set, and plates were separated using the appropriate speed. Force at first separation was divided by plate area (peak stress). Five replications per test condition were made, and results were analyzed using ANOVA and Bonferroni-adjusted t tests (alpha=.05). Within each impression material/test combination, stress using SSD was significantly lower than CA (P<.05). Mechanical retention did not always provide significantly greater strength. The combination of mechanical retention and CA yielded the highest strength within each material type, except for PE, for which nonmechanical and CA strength did not differ from that of mechanical and CA. Use of the self-stick adhesive system provided significantly lower retentive strength to plastic tray material than chemical adhesives for irreversible hydrocolloid, vinyl polysiloxane, and polyether.

Determination of bound and unbound water in dental alginate irreversible hydrocolloid by nuclear magnetic resonance spectroscopy

Objectives Alginate materials are considered unsuitable for precise fixed prosthetic rehabilitation due to their tendency to undergo spontaneous syneresis. Commercial alginate impression materials were investigated using Nuclear Magnetic Resonance (NMR) Spectroscopy to probe the relation between changes in the microscopic water environment and dimensional change to obtain a better understanding of spontaneous syneresis. Methods NMR was used to measure the spin-lattice relaxation times ( T 1) of 1H nuclei in water in alginate matrices to characterize changes in gel structure over time. These results were related to the dimensional stabilities of the alginate impression materials, their chemical compositions, and the Moisture Sorption Isotherms (MSI) obtained by incubation at fixed relative humidities. Results The rate of change of T 1 with time was found to be a better predictor of dimensional stability than MSI. The greatest dimensional stability for the alginate powders investigated was associated with a high filler:alginate ratio and a high Ca:Na ratio. Significance Nuclear magnetic resonance spectroscopy may used to measure changes in alginate impression materials under conditions where no dimensional change can be observed directly. Changes occurred rapidly even at 100% humidity, suggesting the dimensional stability of alginate impression materials is partially independent of the rate of dehydration. The results may open a way to formulate alginate impression materials more suitable for precise fabrication of dental prostheses.

Self-disinfecting irreversible hydrocolloid impression material

Self-disinfecting irreversible hydrocolloid impression material

Determining the complex modulus of alginate irreversible hydrocolloid dental material

Objectives The aim of the study is to investigate the visco-elastic response of an alginate irreversible hydrocolloid dental impression material during setting. Methods A novel squeeze film Micro-Fourier Rheometer (MFR, GBC Scientific Equipment, Australia) was used to determine the complex modulus of an alginate irreversible hydrocolloid dental impression material (Algident, ISO 1563 Class A Type 1, Dentalfarm Australia Pty. Ltd.) during setting after mixing. Data was collected every 30 s for 10 min in one study and every 10 min for a total of 60 min in another study. A high level of repeatability was observed. Results The results indicate that the MFR is capable of recording the complex shear modulus of alginate irreversible hydrocolloid for 60 min from the start of mixing and to simultaneously report the changing visco-elastic parameters at all frequencies between 1 Hz and 100 Hz. The storage modulus shows a dramatic increase to 370% of its starting value after 6 min and then reduces to 55% after 60 min. The loss modulus increases to a maximum of 175% of its starting value after 10 min and then reduces to 94% after 60 min. Significance The MFR enables the changes in the complex modulus through the complete setting process to be followed. It is anticipated this approach may provide a better method to compare the visco-elastic properties of impression materials and assist with identification of optimum types for different clinical requirements. The high stiffness of the instrument and the use of band-limited pseudo-random noise as the input signal are the main advantages of this technique over conventional rheometers for determining the changes in alginate visco-elasticity.

Quality of master impressions and related materials for fabrication of complete dentures in the UK1

The aim of this study was to examine the quality of master impressions and related materials for fabricating complete dentures in the UK. One hundred and fifty pre-piloted questionnaires were distributed to a number of dental laboratories in the UK with large catchment areas. Information requested related to the quality and choice of techniques for the master impression stage of fabricating complete dentures, as well as prescription of materials for occlusal registration, amongst others. All information was recorded anonymously. One hundred and forty-four completed questionnaires were returned. All items were provided on a private basis. Eighty-three per cent (n=119) of master impressions were made using a custom tray, the remainder were made using a plastic stock tray. The most commonly used impression material was zinc oxide-eugenol (42%, n=60), followed by polyvinylsiloxane (39%, n=56) and irreversible hydrocolloid (19%, n=28). Master casts were poured after a minimum of 4 days. Eleven per cent of impressions examined (n=16) were judged to have errors. It was reported that 64% of master impressions (n=92) examined had been disinfected adequately. While this study revealed evidence of good clinical practice, particularly in relation to the selection of impression trays and quality of master impressions for complete dentures, there were some areas of concern, particularly in relation to the disinfection of the impressions examined. Dental practitioners should aim to provide their patients with high-quality prostheses by observing best clinical practice at all times.

Preparation of irreversible hydrocolloids to improve retention of complete dentures

Precise reproduction of anatomical-morphological details of dentures support on working models presupposes adequate application of modern impression materials and casting procedure, as well as minimal dimensional change of these materials. experimental and clinical research is connected to irreversible hydrocolloides and the objective was to examine the most suitable consistency of the alginate as the impression mass for the purpose of improving retention of complete dentures. This research included 35 completely toothless patients, most of who had already had complete dentures, 40-80 years of age and of both sexes. Static adhesion was measured with acrylate plates made of adequate corresponding and various models depending on consistency of the irreversible hydrocolloides. Each model was cut into three parts, the cuts obtained were mutually compared, and computerized graphic charts of each section were made. The results of the research show that there is a greater retention force in the acrylate plates obtained on models casted on an anatomical impression base taken with irreversible hydrocolloides of solid consistency. Analysis of the results shows such quality of impressed tissues that they are practically slightly displaced by the impressions regardless of the consistency of the material impressed. In conclusion it is pointed out that the preparation of irreversible hydrocolloides must be carried out by strictly obeying the powder-water weight ratios. The sections of the models obtained by irreversible hydrocolloides of various consistencies, that is by applying different pressures, point to minimal displacement of tissues and great differences in the retention force in favour of the compressive impression.

Effect of Storage Time on the Accuracy of Casts Made from Different Irreversible Hydrocolloids

Several new irreversible hydrocolloid formulations have recently become available with claims of an improved dimensional stability by the manufacturers. The aim of this study was to evaluate the accuracy of casts made from alginate impression materials poured immediately and after specific storage periods. Five alginates were tested: CA 37 (Cavex); Jeltrate (Dentsply Caulk); Jeltrate Plus (Dentsply Latin America); Hydrogum 5 (Zhermack); and Alginoplast (Heraeus Kulzer). A master model was mounted on a special device and used to obtain the impressions. These impressions were stored at 23 degrees C and 100% relative humidity, then poured with gypsum immediately, and again after 24, 72 and 120 hours. The casts were measured and the data were analyzed by one way analysis of variance (ANOVA) and Tukey test at p<0.05. The dimensional stability of the alginate impressions was both material and time dependent (p<0.05). After 24 hours of storage, only Alginoplast and Hydrogum 5 comply with the master model (p>0.05). After 72 and 120 hours, only Hydrogum 5 was dimensionally stable (p>0.05). The dimensional stability of the alginate impressions is influenced by the selected material and the storage time. Alginate impressions should generally be poured immediately. However, some new types of alginate may have the pouring delayed.

The Effects of Custom Tray Material on the Accuracy of Master Casts

In addition to the impression material, the type of impression tray influences the accurate dimensional transfer of the size and position of the teeth to the master cast. The aim of this study was to determine the accuracy of master casts produced from an alginate impression material using a visible-light-curing resin and autopolymerizing polymethyl methacrylate resin custom tray materials. Two types of custom trays were fabricated from a stainless steel master model with three index studs. Twenty-two irreversible hydrocolloid impressions were made of the master model and then poured with a Type III dental stone. The distances between the reproduced index studs were measured to +/- 0.01 mm with a digital caliper. A one-way analysis of variance (ANOVA) and T-test were used for data analysis. There were no significant differences between the two tray materials for any of the three distances. There were no statistical differences between the master model and the casts made from the two tray materials in the length dimension, but there were significant differences in the vertical dimension. In terms of the width dimension there was a significant difference only between the cold curing group and the master model. Within the limitations of this study, the dimensions of stone casts poured from an impression made using a light-cured tray did not differ significantly from those created from impressions made using autopolymerizing acrylic trays. However, working dies from the light-curing tray impressions were more accurate buccolingually than those from the autopolymerizing acrylic trays. The accuracy of master cast reproduction using visible-light-curing resin or an autopolymerizing polymethyl methacrylate resin custom tray material is acceptable. Although autopolymerizing resin materials require less equipment and are relatively more inexpensive, light-cure tray materials may be the material of choice for custom tray fabrication due to greater accuracy in the buccolingual dimension.

In vitro antimicrobial activity of irreversible hydrocolloid impressions against 12 oral microorganisms

This study evaluated in vitro the antimicrobial activity of irreversible hydrocolloids (one containing an antimicrobial agent) prepared with water or with a 0.2% chlorhexidine digluconate solution against 12 strains of the oral microbiota. Twenty specimens (0.5x1.0 cm) for each group (1. Jeltrate mixed with water; 2. Jeltrate mixed with 0.2% chlorhexidine digluconate solution; 3. Greengel mixed with water; 4. Greengel mixed with 0.2% chlorhexidine digluconate solution) were prepared under sterile conditions and placed in culture media inoculated with the indicator strains. After incubation in aerobiosis or microaerophilia, inhibition of the microbial growth was measured and the results were interpreted. The normal adherence curve revealed a non-normal distribution of the data, so the non-parametric Friedman Test was performed (p<0.05). The antimicrobial activity of the groups was classified in the following order: 1, 3, 4, and 2. The results suggest that the method of preparing irreversible hydrocolloids with a 0.2% digluconate chlorhexidine solution is more effective than the incorporation of an antimicrobial agent in the powder to reduce cross-contamination caused by impressions.

A Self-Disinfecting Irreversible Hydrocolloid Impression Material Mixed with Chlorhexidine Solution

To examine the antibacterial effect and several physical properties of an irreversible hydrocolloid impression material mixed with chlorhexidine solution. The experimental irreversible hydrocolloid specimens were prepared and allocated into four groups (Group0.1 g/L, Group0.2 g/L, Group0.5 g/L, Group1.0 g/L) according to the concentrations of chlorhexidine solution used as the mixing liquid. Specimens mixed with distilled water served as a control. The antibacterial effect, three-dimensional accuracy, flowability, and setting time were tested. Statistical analysis was performed using a one-way analysis of variance and a Tukey test, which was used for multiple comparisons (alpha=.05). Zones of growth inhibition were observed around the test specimens, but not around the control specimens, and there were significant intergroup differences in the diameters of the inhibition zones. In the accuracy test, no significant differences (P>.05) were detected among all the measurements for all groups, and the accuracy was clinically acceptable. Also, no significant differences in the flowability (P=.987) and setting time (P=.103) were detected. Chlorhexidine self-disinfecting irreversible hydrocolloid impression material can exhibit varying degrees of antibacterial activity without influencing the three-dimensional accuracy, flowability, and setting time.

Bacterial, fungal and yeast contamination in six brands of irreversible hydrocolloid impression materials

This study assessed the level of contamination of six commercially available irreversible hydrocolloids (two containing chlorhexidine) and identified the contamination present in the materials. Petri dishes containing selective and enriched culture media were inoculated with alginate powder (0.06 g), in triplicate. After incubation (37 degrees C/7 days), the colony-forming units (CFU) were counted and Gram stained. Biochemical identification of the different morphotypes was also performed. The contamination levels for the materials were: Jeltrate--389 CFU/g; Jeltrate Plus--516 CFU/g; Jeltrate Chromatic--135 CFU/g; Hydrogum--1,455 CFU/g; Kromopan--840 CFU/g; and Greengel--59 CFU/g. Gram staining revealed the presence of Gram-positive bacillus and Gram-positive cocci. The bacteria Staphylococcus epidermidis, Bacillus subtilis, Bacillus sp., Bacillus coagulans, Bacillus licheniformis, Bacillus cereus, Micrococcus luteus, and Nocardia sp.; the filamentous fungi Aspergillus niger, Aspergillus flavus, Rhizopus sp., Neurospora sp.; and the yeast Candida sp. were isolated. The contamination detected in the impression materials points out the need for adopting measures to improve the microbiological quality of these materials. The use of contaminated materials in the oral cavity goes against the basic principles for controlling cross-contamination and may represent a risk for debilitated or immunocompromised patients.

Irreversible Hydrocolloid: An Unusual Presentation of Esophageal Obstruction

Upper digestive tract obstruction can occur after ingestion of various types of foreign bodies. However to the best of our knowledge, no case of a near-total obstruction caused by an irreversible hydrocolloid has heretofore been reported in the literature. We present just such a case, and we discuss our preferred method of removing foreign bodies from the cervical esophagus.

An acrylic resin prosthesis for obturation of an orocutaneous fistula

To obduratethe fistula, an individual acrylic resin device may be fab-ricated to eliminate, as much as possible, secretion anddrooling through the fistula.A60-year-oldwhitewomanunderwentcompleteex-cision of an acinic cell carcinoma in the right parotid re-gion,includingrighteyeenucleation,mandibulectomy,andradicalneckdissection,followedbychemoradiationtherapy. The patient presented to the Department ofMaxillofacial Prosthetics, Hadassah Medical Center,uponcompletionofchemoradiationtherapy,exhibitingexposed bone and titanium mesh on the right lateral as-pect of the mandible and floor of the mouth (Fig. 1).Debris and secretions were accumulating in the fistula,causingirritationandinflammation.Speechbecameim-paired due to air leakage through the fistula. Eating anddrinking became difficult due to constant liquid drain-age through the fistula. The patient was diagnosedwith osteoradionecrosis of the area. Surgical interven-tion was not recommended at this stage due to herlow white blood cell and platelets count, and suspicionof brain metastasis.Anintraoraldevicewasfabricated,asaninterimsolu-tion,untilsurgerywouldbepossible.Thedevice,whichserves as anobturator forthe fistula and restores normaloral function, is supported and retained by the teeth.Clasps were used to engage the abutment teeth to assistwith retention. The device is easy to manufacture andmanipulatebythepatientandpreventsleakageoffluids,air, and debris through the fistula. The patient is able toremove the device as necessary to maintain good oralhygiene. Other advantages include good patient adap-tationtothedeviceandminimalirritationtothesofttis-sue. Since the fistula can become wider, it is importantthat the extension of the device can be relined as tissuechanges occur. The intraoral device does not managethe esthetic problem, which may be resolved with anextraoral prosthesis. The technique for fabricating aprovisional acrylic resin device for obturation of anorocutaneous fistula is described below.PROCEDURE1. Lubricatethefistulawithliquidparaffin(ParaffinOil,Pharmacy Service, Hadassah Medical Center, Jerusa-lem, Israel) before making the impression. Make animpressionofthemandible andtheareaofthefistulawith irreversible hydrocolloid (Alginate ImpressionMaterial, Aroma Fine DF III, Fast Set; GC Corp,Tokyo, Japan).2. Prepare a cast (Microstone Golden; Whip Mix Corp,Louisville, Ky) from the impression.3. Design the device on the cast, considering the pathof insertion, retention, support, and stability.4. Fabricate the device from heat-polymerized acrylicresin (Vertex; Dentimex BV, Zeist, The Netherlands)by investing and processing. Use orthodontic wire(Remanium Spring hard 0.8-mm wire; Dentaurum,Ispringen, Germany) for clasps.

Custom impression tray for dental implants

An accurate impression is mandatory for achieving a precise, definitive fixed implant-supported prosthesis.1-8 An inaccurate impression may result in the need for additional clinical time or remaking the impression.1,7-10 A commonly used implant impression technique is the use of an open custom impression tray.5-7 The dental technician may receive an irreversible hydrocolloid impression for making a custom tray that does not show the implant axis and position. This could require the clinician to further modify the custom tray chairside.

Effect of immersion disinfection with Perform-ID on alginate, an alginate alternative, an addition-cured silicone and resultant type III gypsum casts

This study investigated the effect of a commonly used immersion disinfectant upon three different impression materials and any subsequent effects on the abrasion resistance, hardness and surface detail reproduction of gypsum casts. A laboratory study. Under standardised conditions a total of 120 impressions were made of a ruled test block using irreversible hydrocolloid (Alginoplast), an 'alginate alternative' addition-cure silicone (Position Penta) and a conventional addition-cure silicone (President). The impressions were examined for surface detail reproduction prior to and after disinfection with Perform-ID. The type III casts were evaluated for surface detail reproduction, surface hardness and abrasion resistance. (1) None of the disinfected alginate specimens could reproduce the 50 microm line. (2) Casts produced from the disinfected alginate were significantly less hard than from disinfected Position Penta and President (P <0.001). (3) Disinfection significantly affected the abrasion resistance of casts made from Position Penta (P = 0.029). (4) Disinfection did not significantly affect President or its subsequent casts (P >0.05). If disinfecting with Perform-ID, the impression should be made with a conventional addition-cured silicone if good surface detail reproduction of the impression material and a hard and abrasion resistant type III gypsum cast are required.