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Evaluate (0.2% CHX) Disinfection Solution Effects Incorporation on the Setting Time, Setting Expansion and Compressive Strength of Dental Stone

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Abstract Objective: Evaluate the effect of incorporation of 0.2% Chlorhexidine disinfection solution on the setting time, setting expansion and wet and dry compressive strength of dental stone compared with these obtained control stone. Methods: Preparation of specimen and procedure were at 23±2ºC temperature and 50±10 relative humidity. W/P ratio 100g of stone and 33ml of 0.2% CHX mixed for one minute with manual spatulation at rate I20rpm. Results: 0.2% CHX solution increased the setting time for both types but this increasing clinically significant. Improvement in the dry and wet compressive strength for both types. Setting expansion was increased slightly for both types of stone but it with ADA specification range 0.0-0.2%. Conclusion: 0.2% CHX increased setting time and setting expansion for both types of stone, and it was improved wet and dry compressive strength for both types of stone.
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Evaluate (0.2% CHX) Disinfection Solution Effects Incorporation on the
Setting Time, Setting Expansion and Compressive Strength of Dental
Stone
To cite this article: Ibrahim H. Alfahdawi et al 2019 J. Phys.: Conf. Ser. 1178 012014
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International Workshop in Physics Applications
IOP Conf. Series: Journal of Physics: Conf. Series 1178 (2019) 012014
IOP Publishing
doi:10.1088/1742-6596/1178/1/012014
1
Evaluate (0.2% CHX) Disinfection Solution Effects Incorporation on the Setting
Time, Setting Expansion and Compressive Strength of Dental Stone
Ibrahim H. Alfahdawi1*, Mohammed Gh. Hammed2 , Jamal M. Rzaij2
1Department of Prosthodontics, College of Dentistry, University of Anbar, Ramadi, Iraq
2Department of Physics, College of Science, University of Anbar, Ramadi, Iraq
*Corresponding Author email: ibrahimhm7@yahoo.com
Abstract This study aims to evaluate the effect of incorporation of 0.2%
Chlorhexidine disinfection solution on the setting time, setting expansion and (wet
and dry) compressive strengths of dental stone compared with these obtained
control stone. The method included preparation of specimen and procedure were at
23±2ºC temperature and 50±10 relative humidity. The water/powder (W/P) ratio
100g of stone and 33ml of 0.2% CHX mixed for one minute with manual
spatulation at rate I20rpm. It was found that 0.2% CHX solution increased the
setting time for both types but this is increasing the clinically significant; then
improvement in the dry and wet compressive strength for both types. Setting
expansion was increased slightly for both types of stone but it with American
Dental Associations (ADA) specification range 0.0-0.2%.
Key word: CHX, Setting time, Setting expansion, Compressive strength, Dental
stone
1. Introduction
Gypsum products are used in several places in the dental field. These materials are
possessing high mechanical properties, as high compressive stress, in order to withstand the
working forces when used clinically. The gypsum products strength can be affected by many
factors like, the water/powder ratio, additives, mixing time, etc.[1].
The most serious occupational hazards facing the dental professional are the possibility of
contracting and/or sever infectious diseases transmitting. Diseases can spread by blood or
saliva through directly or indirectly contact with contaminated equipment’s supplies,
instruments, impression and casts which were proved that a potential source lamination of
microbial ion. Therefore, when preparing, fabrication and handling prosthodontic
restorations, additional precaution would be taken [2].
The incorporation of disinfections agent into stone mixture is the best one methods of cast
disinfection. During dental procedure either clinically or laboratory, stone cast should be
exposed to contamination in any time of using and may be repeated exposed to
contamination. In such conditions, the cast would be re-disinfected after each contamination
or as an alternative method is to use an agent of prolonged activity that is able to maintain
self-disinfection against each contamination and serve as effective infection control
program[3].
International Workshop in Physics Applications
IOP Conf. Series: Journal of Physics: Conf. Series 1178 (2019) 012014
IOP Publishing
doi:10.1088/1742-6596/1178/1/012014
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Disinfection of dental stone casts was suggested because of not all impression materials
can be disinfected without adverse effects on the essential properties. Many studies
influenced the antibacterial activity of some disinfectant used for disinfectant of stone casts.
Among different disinfection methods, it was find that disinfectant incorporation was the best
method due to it had double action to disinfection of the impressions in addition to casts[4].
Plaster models disinfection can be carried out by spraying or immersion in a disinfecting
solution, in addition to by the incorporation of antimicrobial agents into the plaster
mixture[5]. It was find that chlorhexidine solution maintained maximum compression
strength, least setting expansion and little increasing of setting time, while gluter aldehyde
showed the great increasing of setting time. Also it was find that high concentration of
chlorhexidine had more effect on mechanical properties than low concentration, these
methods were considered as high efficient and liable method of compared with immersion
and spray methods, due to it permits equal antibacterial agent distribution throughout the
mixture[6].
Disinfectant solution incorporation would not produce adverse effect on the physical or
mechanical properties like compression stress, surface hardness, setting time, setting
expansion and reproduction of detail due to deterioration in these properties will affect the
dental treatment made on such cast[7].
Gypsum products are the most common materials that are used in dentistry widely and
because of the high demand on this material. Efforts could be made to produce the material
locally from local materials. Among the materials used in the dentistry is gypsum products,
and it was one of the different of materials used by the dentist and dental technician[8, 9].
The aim of the study was to investigate the effect of incorporation of 0.2% CHX on the
setting time, setting expansion and compressive strength of dental stone.
2. Materials and Methods
G1: Dental stone + distilled water.
G2: Dental stone + 0.2% CHX solution.
The preparation of 60 test specimens was at temperature environment 23+2°C and 50+10%
relative humidity. Each 100g of stone powder was mixed with 33 ml of 0.2% CHX for Hi-
stone and 38ml for Iraqi stone. 1 min. for mixing at rate 120rpm , followed ADA
specification. Five specimens for each group were evaluated for each test.
2.1. Experimental tests
2.1.1. Setting Time Test
Setting time was measured by standard vicat apparatus (figure 1) according to A. D. A.
specification No. 25 [10]. The conical mold was filled with stone mixture by adding 200g of
stone powder to 66ml of CHX for experimental and distilled water for control stone. The
needle was brought in contact with the surface of stone and locked in its position by thumb
screw. At time of the loss of gloss, the needle was released at 15 seconds interval until the
needle first failed to penetrate the stone completely.
2.1.2. Setting Expansion Test
International Workshop in Physics Applications
IOP Conf. Series: Journal of Physics: Conf. Series 1178 (2019) 012014
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doi:10.1088/1742-6596/1178/1/012014
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Setting expansion device that consist of dial gauge and gauge rod was used (figure 2).
Stone mixture was poured into the stainless steel mold of (28.5x2.5x2.5) cm (figure 3), and
after 30 minutes the mold was disassembled . The stone specimen was placed into selling
expansion device, the initial reading was obtained. After 2 hours the final reading was
measured and setting expansion percentage was calculated.
2.1.3. Compressive Strength Test
Aluminum split molds 20mm in diameter and 40 mm height were filled with stone
mixture. After 30 minutes from mixing, the specimens (figure 4) were kept in desiccators for
30 minutes at 23±2ºC temperature and 95±5% relative humidity. Compressive strength
machine was used with loading rate of 600KN/min (figure 5). Wet strength after 1 hour, and
dry strength after 24 hours were measured.
3. Results and Discussions
The effect of CHX disinfectant solution on the setting time, compressive strength and
setting expansion of experimental stone and control stone are tested (table 1).
Incorporation of chlorhexidine into stone mixture in different concentration was evaluated
immediately after cast separation and after storage period. It was concluded that 0.2% CHX
was enough to give proper disinfection for the dental stone[11, 12].
3.1. Setting Time
The result revealed that CHX disinfectant solution produced noticeable effect on the
setting time of dental stone. Increased setting time was found by Al-Shakhily, 1995 for both
concentrations of CHX solution (0.2,0.5%). Probably CHX solution act as retarder by either
coat the particles of hemihydrates which inhibit the rate of solution or react with either the
calcium or sulfate ions. Also retarder consists of salts, that form a layer of a calcium salt that
is less soluble than the sulfate.
3.2. Setting Expansion
The percentage of setting expansion of two types of stone was shown. It was found that
the incorporation of CHX disinfectant solution into stone mixture increased the setting
expansion for both experimental and control stone than that found with distilled water [13].
Al-Shakhily, 1995 found that CHX increased the setting expansion. This is in contrast with
[14, 15] who stated that the thicker the mix of hemihydrate, the greater the expansion. This
higher expansion for new Iraqi stone might be due to dense and smaller size particle powder,
leading to higher number of particles, thus higher summation of growth and higher expansion
at the end. Also, higher expansion might be due to modifiers that added by manufacture [16].
Confirmed that the addition of sodium chloride (NaCl) in small concentration increase the
setting expansion of mass. The A.D.A. specification recommended the accented range of
(0.0%-0.2%) for setting expansion.
3.3. Compressive Strength
International Workshop in Physics Applications
IOP Conf. Series: Journal of Physics: Conf. Series 1178 (2019) 012014
IOP Publishing
doi:10.1088/1742-6596/1178/1/012014
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Incorporation of CHX solution produced an increase in the wet and dry compressive
strength for both types of stones than that showed with distilled water [13]. Alshakhily, found
that 0.5% CHX solution increase significantly the compressive strength of dental stone, this
might be due to increase in cohesion between the crystals of dihydrate produced by CHX
incorporation. Wet compressive strength (after 1 hour from mixing) for control stone was
higher than value recorded for new experimental stone. Dry compressive strength (after 24
hours) decreased for experimental stone than control stone, since the higher w/p ratio, the
more the porosity [14]. This reduction in wet and dry compressive strength is in agreement
with [12, 16]. No significant difference in dry compressive strength between the two types of
stone was recorded.
4. Conclusion
In was found that using 0.2% CHX solution increased the setting time for both types of
stone, but this increase in setting time might be clinically significant.An improvement in the
wet and dry compressive strength for control stone and experimental stone was found.A
slight increasing in setting expansion for both types was detecting. Within A. D. A.
specification ranges (0.0%-0.2%); CHX (0.2% concentration) can be used as disinfectant
solution to be incorporated into stone mixture for cast disinfection.
References
[1] W. A. Razak, I. N. Yassin, and F. A. Kati, “Effect of Adding some Additives and
Drying Method on Compressive Strength of Gypsum Products,” Tikrit J. Dent. Sci.,
vol. 5, no. 20731213, pp. 2532, 2017.
[2] A. B. Carr and D. T. Brown, McCracken’s Removable Partial Prosthodontics-E-Book.
Elsevier Health Sciences, 2010.
[3] K. T. Altieri, P. V. Sanita, A. L. Machado, E. T. Giampaolo, A. C. Pavarina, and C. E.
Vergani, “Effectiveness of two disinfectant solutions and microwave irradiation in
disinfecting complete dentures contaminated with methicillin-resistant Staphylococcus
aureus,” J. Am. Dent. Assoc., vol. 143, no. 3, pp. 270277, 2012.
[4] H. Aeran, A. Agarwal, V. Kumar, and J. Seth, “Study Of The Effect Of Disinfectant
Solutions On The Physical Properties Of Dental Impressions.,” Indian J. Dent. Sci.,
vol. 6, no. 3, PP: 67-69,2014.
[5] M. G. Lucas, J. N. Arioli, Filho, S. S. Nogueira, A. U. D. Batista, and R. D. P. Pereira,
“Effect of incorporation of disinfectant solutions on setting time, linear dimensional
stability, and detail reproduction in dental stone casts,” J. Prosthodont. Implant.
Esthet. Reconstr. Dent., vol. 18, no. 6, pp. 521526, 2009.
[6] J. Davies and D. Davies, “Origins and evolution of antibiotic resistance,” Microbiol.
Mol. Biol. Rev., vol. 74, no. 3, pp. 417433, 2010.
[7] J. F. McCabe and A. W. G. Walls, Applied dental materials. John Wiley & Sons, 2013.
[8] M. M. A.-N. I.H. Al-Fahdawi, M. Gh. Hammed, “Effect of the Addition of Styrene-
Butadine (S-B) Dissolved in Tetra Hydro Furan (Thf) on the Some Mechanical
Properties of Heat-Cured Acrylic Resin Denture Base Materials,” Egypt. Dent. J., vol.
International Workshop in Physics Applications
IOP Conf. Series: Journal of Physics: Conf. Series 1178 (2019) 012014
IOP Publishing
doi:10.1088/1742-6596/1178/1/012014
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56, no. 2, pp. 947
952, 2010.
[9] B. W. Darvell, Materials science for dentistry. Woodhead publishing, 2018.
[10] A. D. Association, “Council on Dental Materials. ANSI/ADA specification no. 25 for
dental gypsum products,” 2010.
[11] G. B. de A. Cubas, “Efetividade da antissepsia bucal prévia com clorexidina na
prevenção da contaminação da moldagem com alginato e sua influência na distorção
do material,” 2012.
[12] B. M. A. Hussein, “The antibacterial activity of certain disinfectant solutions
incorporated into stone mixture,” Mustansiriya Dent. J., vol. 5, no. 2, pp. 200204,
2018.
[13] Q. A. Mohammad, R. H. Hasan, and S. S. Thiab, “Effects of different disinfectant
additives on compressive strength of dental stone,” J. Univ. Babylon, vol. 22, no. 5, pp.
16861695, 2014.
[14] R. Siddique, P. Aggarwal, and Y. Aggarwal, “Influence of water/powder ratio on
strength properties of self-compacting concrete containing coal fly ash and bottom
ash,” Constr. Build. Mater., vol. 29, pp. 7381, 2012.
[15] Firas Abd Kati, Ihab N. Yassin and Wael Abdul Razak, Effect of Adding some
Additives and Drying Method on Compressive Strength ofGypsum Products, Tikrit
Journal for Dental Sciences, 5 (2017), pp. 25-32
[16] Lorela Georgeta Sfarghiu, Luminița Oancea, Ruxandra Lițescu, Mihai Burlibașa, Liliana
Moraru, The Influence of Disinfectants Incorporation on Die Stone Linear Expansion,
Romanian Biotechnological Letters, 21 (3) (2016)
Table 1: The Effect of Chlorhexidine Solution (0.2 % CHX ) Incorporation on the Setting Time,
Setting Expansion and Compressive Strength of Iraqi and Hi-Japanese Dental Stone (mean and
Standard Deviation)
Groups
S. T. (min.)
S. Exp. (%)
Wet C. S. kg/cm2
Group 1
16.52±0.5
0.07±0.008
358.62±10.43
Group 2
25.81±0.4
0.11±00.007
302.74±14.42
G1: Hi-stone+0.2 CHX
G2: Iraqi stone+0.2 CHX
International Workshop in Physics Applications
IOP Conf. Series: Journal of Physics: Conf. Series 1178 (2019) 012014
IOP Publishing
doi:10.1088/1742-6596/1178/1/012014
6
Figure 1: Standard vicat apparatus. Figure 2: Setting expansion device.
Figure 3: Stainless steel mold and specimen of
setting expansion test.
Figure 4: Compressive strength test Figure 5: Compressive strength machine.
specimen.
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