Antimicrobial effect of 4 disinfectants on alginate, polyether, and polyvinyl siloxane impression materials

PURPOSE: Dental impressions often carry microorganisms that may cause cross infection from patients to dental staff. The aim of the current study was to determine the effectiveness of 4 different disinfectant solutions on 3 commonly used impression materials--alginate, polyether, and polyvinyl siloxane--to establish a protocol for disinfection of these impression materials after clinical exposure and prior to handling in the dental laboratory. MATERIALS AND METHODS: A total of 45 impressions were taken from the maxillary dentate arches of 15 dental staff participants at the Department of Dentistry, Prince Rashid Hospital, Irbid, Jordan. For each participant, 3 successive impressions were recorded in the different impression materials. For each impression, 6 specimens were dissected from 6 different locations and exposed to 6 different regimens: 1 was left untreated, 1 was immersed in sterile water for 10 minutes to serve as a control, and the remaining 4 specimens were exposed to 4 different disinfection treatments (Dimenol, Perform-ID, MD 520, and Haz-tabs). Serial dilutions of the suspension were carried out and counted by the Miles-Misra technique (inoculation on Columbia blood agar for quantification). The dilutions were aerobically incubated at 37 degrees C for 48 hours. RESULTS: The disinfectants were able to completely eliminate microorganisms carried by the impressions. For those undisinfected specimens, the results showed that untreated alginate impressions appear to carry more microorganisms (P < .05) than the other 2 rubber impression materials used in the study. For those specimens immersed in sterile water for 10 minutes (control group), the number of microorganisms eliminated was increased from 62% to 90% compared to those left untreated. CONCLUSION: Impression materials may act as a vehicle for the transfer of microorganisms from the patient's mouth to dental personnel. Impressions should be disinfected to eliminate the risk of cross contamination.     

Influence of technique and pouring time on dimensional stability of polyvinyl siloxane and polyether impressions

This study aimed to determine how impression technique and pouring time affect casts obtained using polyvinyl siloxane (PVS) and polyether (PE) impressions. A total of 480 impressions were taken using three techniques: single-step (SS), two-step (TS), and two-step with a spacer (TSS). Impressions were poured after 1 and 24 hours and 7 and 14 days. Significant differences (P < .01) were found between the TS technique and the SS and TSS methods as well as between PE and PVS (P < .01) in terms of the effects of pouring time. SS and TSS yielded similar dimensional results, while greater dimensional change was induced with TS. PE impressions had to be poured no later than 7 days after preparation to ensure dimensional stability.     

The dimensional accuracy of polyvinyl siloxane impression materials using two different impression techniques: An in vitro study

Aim of the Study:

To evaluate and compare the linear dimensional changes of the three representative polyvinyl siloxane (PVS) impression materials and to compare the accuracy of single mix with double mix impression technique.

Methodology:

A study mold was prepared according to revised American Dental Association specification number 19 for nonaqueous elastic dental impression materials. Three PVS impression materials selected were Elite-HD, Imprint^™ II Garant, Aquasil Ultra Heavy. Two impression techniques used were single mix and double mix impression technique. A total of 60 specimens were made and after 24 h the specimens were measured using profile projector.

Statistical Analysis:

The data were analyzed using one-way analyses of variance analysis and significant differences were separated using Student''s Newman–Keul''s test.

Results:

When all the three study group impression materials were compared for double mix technique, the statistically significant difference was found only between Imprint^™ II Garantand Elite-HD (P < 0.05). Similarly, using single mix technique, statistically significant difference were found between Elite-HD and Imprint^™ II Garant (P < 0.05) and also between Aquasil Ultra Heavy and Elite-HD (P < 0.05). When the linear dimensional accuracy of all three impression material in double mix impression technique and single mix impression technique were compared with the control group, Imprint^™ II Garant showed the values more nearing to the values of master die, followed by Aquasil Ultra Heavy and Elite-HD respectively.

Conclusion:

Among the impression materials Imprint^™ II Garant showed least dimensional change. Among the impression techniques, double mix impression technique showed the better results.Key Words: Dimensional accuracy, double mix impression technique, impression materials, polyvinyl siloxane, single mix impression technique     

The effect of various base/core materials on the setting of a polyvinyl siloxane impression material

Five resin-modified glass ionomers and amalgam, used as a base or core buildup material, were clinically evaluated for whether they effected polymerization of a low viscosity (light body) regular set polyvinyl siloxane impression material. A total of 20 samples per group was prepared according to the manufacturer's recommendations. Ten samples from each group were handled with latex gloves during mixing and the other 10 were handled with vinyl gloves. Five of the 10 samples had the outer surface prepared with a round diamond wheel. Impressions were made of all the samples. The impression materials were visually scored inhibited or noninhibited. Inhibited impression materials met at least one following criterion: (1) an oily substance on the surface of the impression readily collected on a sterile explorer tine as it was moved across the impression surface; (2) a rippled appearance on the surface of the impression material; or (3) unpolymerized impression material adherent to the prepared sample surface. If none of the criteria were observed, the impression was scored noninhibited. The data were analyzed with the chi square analysis (level of significance p = 0.05). Total chi square analysis revealed a significant difference between brands (p = 0.0001) and between prepared and non-prepared samples (p = 0.001). Interrater reliability data were analyzed with the kappa correlation analysis. Raters were in complete agreement (kappa = +1). The prepared samples of Vitrebond material had an inhibitory effect on the polymerization of Express impression material.     

Long-term dimensional stability and reproduction of surface detail of four polyvinyl siloxane duplicating materials

OBJECTIVES: Duplicating materials must routinely accurately reproduce the details of dental casts and thus contribute significantly to the close adaptation and success of a removable prosthesis or fixed indirect restoration. It is important to establish the long-term dimensional stability of polyvinyl siloxane materials (PVS) as they are widely used in dental technology and over the duration of a course of treatment, are stored under dental laboratory conditions. The dimensional stability of four PVS duplicating materials was investigated over a 13-week period. MATERIALS AND METHODS: Forty PVS duplicate moulds of a partially dentate maxillary arch were produced from four materials (Elite double 8, Gemini transparent, C & J pourable silicone and Z Dupe). Three dimensions were measured in triplicate at baseline 1, 5, 9 and 13 weeks using computerised image analysis. Half of the specimens were measured following storage at room temperature (21+/-2 degrees C) and half at 37 degrees C to represent storage in hot climates. Specimens for scanning electron microscopy were prepared by duplicating a rugosity standard. RESULTS: At room temperature two materials Elite Double 8 and Z Dupe showed no statistically significant dimensional change, the other two materials showed a slight increase of dimensions. Specimens stored at 37 degrees C showed greater differences in dimensions with Z Dupe showing statistically significant shrinkage. SEM investigation showed no surface deterioration of two materials. CONCLUSIONS: None of the materials showed a change in dimension greater than 2% and the four PVS materials showed good dimensional stability over the time period of the study.     

湿度对聚醚橡胶印模精度的影响

目的:评价两种聚醚橡胶Polyjel NFTM(PO)和ImpregumTMSoft(IM)在5种湿度下放置24 h后印模尺寸的变化,并与在同种条件下存放的亲水性硅橡胶ExpressTMXT(EX)进行对比研究。方法:采用国际牙科组织(ADA)推荐使用的标准不锈钢模具制取印模。将印模分别放置于不同湿度下:30%、50%、70%、90%、浸水,温度恒定为23℃。放置24 h后,使用万能工具显微镜测量每个样本中间水平线的长度和标准模具上同一条水平线的长度,计算印模尺寸变化率,衡量印模尺寸变化。结果:在5种湿度下,印模材料间存在显著性差异(P<0.05);每种材料,湿度间差异有统计学意义(P<0.05)。在湿度30%时,3种材料之间的差异无统计学意义(P>0.05)。湿度为50%、70%时,IM和PO无明显差异,两者尺寸变化均明显小于EX。湿度90%、浸水时,尺寸变化顺序:PO>IM>EX。结论:PO、IM在湿度70%的环境下存放,能获得最精确的印模。EX印模浸泡在水中精度最高。     

The dimensional stability of elastomeric impression materials following disinfection

Public awareness of infectious diseases has focused attention on the prevention of nosocomial disease. Difficulties in sterilizing impressions have led to chemical disinfection as an alternative. Recent literature indicated a lack of consensus between researchers about distortion caused by disinfection. A polysulfide, polyether, and vinyl polysiloxane were disinfected by immersion in iodophor, sodium hypochlorite, and glutaraldehyde. Distortion was evaluated by use of a stainless steel die (ADA specification No. 19). Linear dimension variations after disinfection were clinically insignificant.     

The effects of disinfectants on the dimensional stability of alginate impression materials

Glutaraldehyde and hypochlorite solutions have been shown to be effective disinfectants for use in the dental surgery. However, their use in the disinfecting of alginate hydrocolloid impression materials must be open to question since these materials are dimensionally unstable when immersed in aqueous solutions for any length of time. This project investigated the dimensional changes noted in casts poured into alginate impressions which had been stored for up to 60 minutes in either hypochlorite or glutaraldehyde solutions. All changes measured were considered to be within clinical tolerance.     

Linear dimensional accuracy of a polyvinyl siloxane of varying viscosities using different impression techniques

Abstract Aim: The present study is an in vitro study to evaluate the linear dimensional accuracy of commercially available polyvinyl siloxanes of varying viscosities using different impression techniques. Methods: Different impression techniques used were: (a) putty wash, with a two‐step technique with polyethylene spacer, using a stock tray; (b) putty wash, with a one‐step technique, using a stock tray; (c) single‐mix technique, utilizing medium viscosity in a custom tray; and (d) multiple‐mix technique, utilizing a heavy‐ and low‐viscosity combination in a custom tray. For each technique, 10 impressions were made of a metallic maxillary dentulous master model. Results: The result of this study dictates that a heavy‐ and low‐viscosity combination, double‐mix technique in a custom tray produced an accurate result in all dimensions, followed by the single‐mix technique, utilizing medium viscosity in a custom tray, and the putty wash two‐step technique with polyethylene spacer, using a stock tray. Group 2 putty wash, one‐step, simultaneous technique produced the least accurate result in all dimensions. Conclusion: The putty wash two‐step techniques were found to be as accurate as the multiple‐mix technique, utilizing a heavy‐ and low‐viscosity combination in a custom tray, and the single‐mix technique, utilizing medium viscosity in a custom tray. Making custom trays is time consuming and costly.     

The effect of a range of disinfectants on the dimensional accuracy and stability of some impression materials

Disinfection of dental impressions should be considered as a routine procedure in dental surgeries and dental laboratories. Disinfectants can have deleterious effects on some properties of impression materials. The aim of this study was to evaluate the dimensional accuracy and dimensional stability of a model dental stone, reproduced from five commonly used impression materials (Aquasil soft putty/Aquasil Ultra LV; Aquasil Monophase; Aquasil Ultra Heavy; Impregum F and Provil putty/Provil Light CD wash) retained by their adhesives in acrylic resin trays and exposed to three disinfectant solutions (Perform ID; Haz-Tabs and MD 520). Two hundred models were used to investigate the effect of the three disinfectants on the dimensional accuracy of the five impression materials. Five impressions were taken for each impression material for each disinfection treatment group. Measurements were carried out using a High Precision Reflex Microscope. All materials demonstrated a percentage change in dimensions when subjected to no disinfection when compared to the brass master die and all materials demonstrated a percentage change in dimension when subjected to the different disinfection procedures. The results of this study have demonstrated that for all of the materials investigated, the changes in dimensional stability were small in the order of microns. These changes may however be of clinical significance for procedures requiring a high degree of accuracy, for example fixed prosthodontics. The materials respond differently depending on the disinfectant used and it may therefore be appropriate that manufacturers recommend the use of particular disinfectants for their products in order to ensure optimum dimensional accuracy and stability.     

Factors affecting the dimensional stability of elastic impression materials

The sources of inaccuracy which can develop during and after the use of elastic impression materials were analysed. Experiments designed with this analysis in mind were performed on both the hydrocolloid and elastomeric groups of these materials. (The dimensional differences between stone models poured at intervals between 1 hour and 1 week of both undercut and non-undercut metal master models were used in an assessment of the dimensional accuracy and stability of each type of material.) The lead-dioxide-cured polysulphide and the imine-terminated polyether impression materials were least affected by the strain accompanying their withdrawal from undercut regions. During storage the lead-dioxide-cured polysulphides were the least susceptible to both water absorption and solvent loss, whereas the polyether material absorbed water and swelled. The silicone polymers and the hydrocolloid materials did not maintain their accuracy during long storage.     

Accuracy of three polyvinyl siloxane putty-wash impression techniques

STATEMENT OF PROBLEM. There is much discussion in the dental literature concerning the effect of the impression technique on the accuracy of cast restorations. PURPOSE. This study assessed the accuracy of 3 putty-wash impression techniques using the same impression material (polyvinyl siloxane) in a laboratory model. MATERIAL AND METHODS. The 3 putty-wash impression techniques used were (1) 1-step (putty and wash impression materials used simultaneously); (2) 2-step with 2-mm relief (putty first as a preliminary impression to create 2-mm wash space with prefabricated copings. In the second step, the wash stage was carried out); and (3) 2-step technique with a polyethylene spacer (plastic spacer used with the putty impression first and then the wash stage). For each technique, 15 impressions were made of a stainless steel master model that contained 3 complete crown abutment preparations, which were used as the positive control. Accuracy was assessed by measuring 6 dimensions (intraabutment and interabutment) on stone dies poured from impressions of the master model. RESULTS. One-way analysis of variance showed statistically significant differences among the 3 putty-wash impression techniques, for all intraabutment and interabutment measurements (P <.001). Overall discrepancies of the 2-step technique with 2-mm relief putty-wash impression technique were significantly smaller than that in the 1-step and polyethylene putty-wash impression techniques. CONCLUSION. The polyvinyl siloxane 2-step, 2-mm, relief putty-wash impression technique was the most accurate for fabricating stone dies.     

The dimensional stability of impression materials and its effect on in vitro tooth wear studies

Objectives

To assess the dimensional stability of 8 impression materials over 12 weeks relevant to in vitro tribology studies.

Methods

Ten impressions from eight impression materials were taken of a metal block (ADA block) conforming to the American Dental Association specification for impression materials and of another metal block (custom block) which allowed measurements over a larger surface area. The impressions and blocks were scanned on a non-contacting laser profilometer (Taicaan^® - Southampton, UK) and using surface metrology software Boddies^® (Taicaan^® - Southampton, UK) measurements were made at 24 h, 2, 4, 8 and 12 weeks. The impression materials tested were [1] Aquasil^®, [2] Aquasil^® DECA, [3] Affinis^®, [4] Express^®, [5] Extrude^®, [6] Impregum^®, [7] President^® and [8] Take 1^®.

Results

Seven addition silicones and one polyether [6] were tested. [2] and [6] were monophasic, the rest were putty-wash. The results from impressions of the ADA block showed that all materials contracted compared to measurements obtained directly from the block [1] expanded over time (+31.5 μm) (p < 0.05). The results from the custom block showed that all materials contracted compared to direct measurements of the block. [4] and [7] expanded over time (+62 μm and +63.8 μm respectively). [8] contracted over time (−54.7 μm) (p < 0.05).

Significance

No material showed linear changes >1.5% and were stable for 12 weeks. Nevertheless, the range of changes would affect tribology studies were cut-offs lesser than the reported changes are selected. All impressions should be processed after similar time delays to reduce the errors introduced by dimensional changes.