A study on the effect on surface detail reproduction of alginate impressions disinfected with sodium hypochlorite and ultraviolet light - An In Vitro study

Impression Disinfection and Its Effect on Dimensional Accuracy and Surface Detail in the Times of COVID-19: An In Vitro Study

Introduction The disinfection of impressions is crucial to eliminate the viral and other microbial loads to prevent the cross contamination of diseases. The aim of this study was to compare the effect of different virucidal disinfecting methods on the dimensional accuracy and surface detail reproduction (SDR) of impression materials. Methods A total of 160 samples were fabricated with different impression materials using zinc oxide eugenol (Group 1), alginate (Group 2), polyether (Group 3), and addition silicone (Group 4) impression materials, each containing 40 samples (n=40). These groups were further divided into Subgroups A, B, C, and D (n=10) based on the disinfecting method used. Disinfection was carried out using 0.2% peracetic acid (A), a natural polymer of glucosamine (B), ultraviolet (UV) radiation (C), and ozonated water (D). The disinfected impressions were poured in type IV gypsum, and the obtained casts were checked for dimensional accuracy and surface detail reproduction (SDR). For dimensional accuracy, a one-way analysis of variance (ANOVA) test and, for surface detail reproduction, the chi-square test were used to compare the different subgroups of each impression material separately. Results Zinc oxide eugenol samples showed the lowest mean dimensional change when disinfected with 0.2% peracetic acid (1A=154.1 µm), and alginate showed the lowest mean dimensional change when disinfected using ozonated water (2D=134.9 µm). On the other hand, the lowest mean dimensional change observed in polyether and addition silicone samples was those which were disinfected using UV radiation (3C=100.9 µm and 4C=113.5 µm). Surface detail was reproduced adequately in most of the samples. Conclusion A 0.2% peracetic acid could be used to disinfect zinc oxide eugenol impressions, ozonated water for alginate impressions, and UV radiation for polyether and addition silicone impressions.

Antimicrobial Efficiency of Hypochlorous Acid and Its Effect on Some Properties of Alginate Impression Material

Dental clinicians and professionals need an affordable, nontoxic, and effective disinfectant against infectious microorganisms when dealing with the contaminated dental impressions. This study evaluated the efficiency of hypochlorous acid (HOCl) as an antimicrobial disinfectant by spraying technique for the alginate impression materials, compared with sodium hypochlorite, and its effect on dimensional stability and reproduction of details. HOCl with a concentration of 200 ppm for 5 and 10 min was compared with the control group (no treatment) as a negative control and with sodium hypochlorite (% 0.5) as a positive control. Candida albicans, Staphylococcus aureus, and Pseudomonas aeruginosa were selected to assess the antimicrobial activity with the colony forming unit test in addition to the dimensional stability and reproduction of details tests. The results revealed that HOCl had significant antimicrobial activity against all tested microorganisms and experimental time. Interestingly, HOCl showed no impact on the dimensional stability of alginate impression material. HOCl could be an effective antimicrobial agent for alginate impression material without interfering with their surface details and dimensional stability.

Disinfection efficacy of sodium hypochlorite and glutaraldehyde and their effects on the dimensional stability and surface properties of dental impressions: a systematic review

Objective

To systematically evaluate the disinfection efficacy of the two most frequently used disinfectants, sodium hypochlorite and glutaraldehyde, and their effects on the surface properties of four different dental impression materials.

Methods

A systematic literature search was performed in four databases until May 1st, 2022 to select the studies which evaluated disinfection efficacy of disinfectants or surface properties of dental impressions after chemical disinfection.

Main results

A total of 50 studies were included through electronic database searches. Of these studies, 13 studies evaluated disinfection efficacy of two disinfectants, and 39 studies evaluated their effects on the surface properties of dental impressions. A 10-minute disinfection with 0.5-1% sodium hypochlorite or 2% glutaraldehyde was effective to inactivate oral flora and common oral pathogenic bacteria. With regard to surface properties, chemical disinfection within 30 min could not alter the dimensional stability, detail reproduction and wettability of alginate and polyether impressions. However, the wettability of addition silicone impressions and the dimensional stability of condensation silicone impressions were adversely affected after chemical disinfection, while other surface properties of these two dental impressions were out of significant influence.

Conclusions

Alginate impressions are strongly recommended to be disinfected with 0.5% sodium hypochlorite using spray disinfection method for 10 min. Meanwhile, elastomeric impressions are strongly recommended to be disinfected with 0.5% sodium hypochlorite or 2% glutaraldehyde using immersion disinfection method for 10 min, however, polyether impression should be disinfected with 2% glutaraldehyde.

An in vitro study of a custom-made device for thermoregulation of the mixing slab on the setting properties of zinc oxide eugenol impression paste

Aim

The present study was aimed to investigate the functional relationship between the mixing temperature and properties of a commercially available zinc oxide eugenol impression paste (ZnOE paste).

Settings and Design

In-vitro study.

Materials and Methods

A custom-made simulated mixing device was indigenously designed to maintain different mixing temperatures, simulating cold, ambient, and hot weather. A commercially available ZnOE paste was mixed according to the manufacturer's instructions in the simulated mixing device at the temperatures ranging from 10°C to 50°C. Initial setting time and consistency were measured according to A. D. A. Specification No. 16 (n = 8). A stainless-steel die having 25, 50, and 75 μm lines was used for surface detail reproduction. Detail reproduction of the stone casts of the impressions was evaluated with a stereomicroscope at 30 magnification (n = 8). The shear bond strength of ZnOE paste to self-cure acrylic tray resin was measured by using the UTM at a crosshead speed of 0.5 mm/min (n = 8).

Statistical Analysis Used

Data were analyzed by using one-way analysis of variance (ANOVA) and Tukey's post hoc tests at a confidence interval of 95% (alpha =0.05).

Results

Initial setting time, consistency, and detail reproduction of the ZnOE paste were affected by the mixing temperature (P < 0.001). Mixing ZnOE paste at a lower temperature of 10°C and higher temperatures of 40°C and 50°C resulted in shorter initial setting time, thicker consistency, and poor detail reproduction. However, no significant difference was obtained in the shear bond strength among the different mixing temperatures evaluated (P > 0.05).

Conclusion

Based on this in vitro study, it is advisable to perform the manipulation of ZnOE paste at a clinical/laboratory temperature of 30°C for optimum performance. The simulated mixing device used in this study can be an alternative for extreme climatic conditions.

The accuracy of gypsum casts obtained from the disinfected extended-pour alginate impressions through prolonged storage times

Background

Manufacturers of the extended-pour alginates claimed their dimensional stability through prolonged storage. No data confirmed the ability of these materials to maintain their dimensions and the reproduced oral details following their chemical disinfection. Therefore, this study evaluated the dimensional stability and surface detail reproduction of gypsum casts obtained from disinfected extended-pour alginate impressions through different storage time intervals.

Methods

Two hundred and forty three hydrocolloid impressions were made from one conventional (Tropicalgin) and two extended-pour (Hydrogum 5 and Chromaprint premium) alginates. These impressions were subjected to none, spray and immersion disinfection before their storage in 100% humidity for 0, 72 and 120 h. The dimensional stability and the surface detail reproduction were indirectly evaluated under low angle illumination on the resulted gypsum casts. At α = 0.05, the parametric dimensional stability data were analyzed using One-Way ANOVA and Tukey’s comparisons, while the nonparametric detail reproduction data were analyzed using KrusKal Wallis and Mann–Whitney's tests.

Results

All gypsum casts exhibited a degree of expansion; however, the recorded expansion values did not differ between test categories (P > 0.05). Generally, casts obtained from spray-disinfected impressions showed lower detail accuracy (P < 0.05). Immersion-disinfected extended-pour alginates produced casts with better detail accuracy following 120 h of storage (P < 0.05).

Conclusion

All alginates materials offer comparable cast dimensions under different testing circumstances. Extended-pour alginates offer casts with superior surface details following their immersion disinfection and 120 h of storage. Spray-disinfection using 5.25% sodium hypochlorite affects the surface details of casts obtained from conventional and extended-pour alginates adversely.

Comparative evaluation of the effect of electrolyzed oxidizing water on surface detail reproduction, dimensional stability and Surface texture of poly vinyl siloxane impressions

Aim:

The aim of this in vitro study was to comparatively evaluate the effect of chemical disinfectants on the surface detail reproduction, dimensional stability and surface texture of polyvinyl siloxane (PVS) impressions.

Materials and Methods:

The impressions were then divided into five groups (fifteen samples per group) and subjected to a ten minutes immersion with 2% glutaraldehyde (Group I), 1% sodium hypochlorite (Group II), freshly prepared electrolyzed oxidizing water (EOW) with different pH values - acidic (Group III), alkali (Group IV) and neutral (Group V). The samples were examined pre and post-immersion under visual observation for surface detail reproduction, travelling microscope for measurement of dimensional stability and surface profilometer (3D) for evaluation of surface texture. A standardized master die was fabricated and seventy-five PVS test samples were made. The samples were subjected to immersion disinfection and studied for surface detail reproduction, dimensional stability and surface texture. Post-hoc test, paired t test and ANOVA were used to analyze dimensional stability statistically both within and between the test groups.

Results:

The surface detail reproduction was satisfactory with both pre and post-immersion test samples. A statistically significant dimensional change was observed post-immersion in Groups II, III and V test samples and a statistically insignificant dimensional change was observed in Groups I and IV test samples. There was a negligible change in surface texture post-immersion in Groups I, III, IV and V test samples with a slight increase in surface roughness post-immersion in Group II samples.

Conclusion:

In this study, all the test disinfectants produced satisfactory surface detail reproduction on Polyvinyl siloxane impressions. 2% glutaraldehyde and electrolyzed oxidizing water (alkali) have resulted in statistically insignificant dimensional change, while 1% sodium hypochlorite, electrolyzed oxidizing water (acidic) and electrolyzed oxidizing water (neutral) have resulted in statistically significant dimensional changes. All the test disinfectants except 1% sodium hypochlorite showed a reduction in surface roughness (Ra) values.

Evaluation of dimensional accuracy for different complete edentulous impressions immersed in different disinfectant solutions

OBJECTIVE

The aim of this study was to evaluate the effects of two different disinfectant solutions' immersion on the dimensional accuracy of different complete edentulous impressions.

MATERIALS AND METHODS

A specific custom-made metallic cast template was constructed and used for making both 120 alginate and zinc oxide eugenol (ZOE) paste impressions (60 for each). Disinfectants with 1% sodium hypochlorite and 2% glutaraldehyde were used for 10 and 60 min immersion of both impressions. After immersion time, the impressions were used for constructing 120 completely edentulous master stone models and divided into different groups according to the study. An electronic caliper was used for dimensional accuracy measurements of the casts. The data were collected and statistically analyzed according to the independent paired sample t-test at statistically significant level P < 0 05. One-way ANOVA test was used to compare between significant different groups.

RESULTS

There is no statistically significant difference in dimensional accuracy of alginate and ZOE paste impressions as disinfection with 1% sodium hypochlorite and 2% glutaraldehyde for 10 min and ZOE paste impressions for 60 min, where there is statistically significant difference in alginate impressions dimensional accuracy as disinfection with 1% sodium hypochlorite and 2% glutaraldehyde for 60 min.

CONCLUSIONS

Possibility of ZOE impressions paste disinfected with 1% sodium hypochlorite and 2% glutaraldehyde for 10 or 60 min, not affecting on dimensional stability, while alginate impressions, only 10 min immersion in disinfectant not affecting the dimensional stability.

Comparison of antimicrobial activities and compressive strength of alginate impression materials following disinfection procedure

AIM

This study investigated the effectiveness of disinfecting solution when incorporated into alginate powder instead of water against some microorganisms and on compressive strength of alginate.

MATERIALS AND METHODS

For measuring antimicrobial activity of alginate, 60 alginate specimens were prepared and divided into two groups: One with water incorporated in the mix (control) and the other with 0.2% chlorhexidine digluconate incorporated in the mix instead of water. The tested microorganisms were: gram +ve cocci, gram -ve bacilli and yeast (each group 10 samples). For measuring compressive strength, 20 specimens of alginate were divided into two groups: One with water incorporated in the mix (control) and the other with chlorhexidine incorporated in the mix.

RESULTS

The statistical analysis of antimicrobial efficacy of alginate was performed with Mann-Whitney U-test, which revealed very high significant difference when comparing among groups (p < 0.000). Student t-test analyzed the compressive strength data which revealed nonsignificant difference between groups (p > 0.05).

CONCLUSION

The incorporation of disinfecting agents into impression materials could serve an important role in dental laboratory infection control and it had no adverse effect on compressive strength of the hydrocolloid alginate.

CLINICAL SIGNIFICANCE

The risk of transmitting pathogenic microorganisms to dental laboratories via impression has been considered a topic of importance for a number of years.