4 review of literature

Review Of Literature

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HERBERT D. AYERS et al (1960)12 conducted a detail duplication test to

evaluate elastic impression materials. Conclusions from the study were that a difference

can be demonstrated in the ability of various impression materials to reproduce fine

surface detail. Polysulfide rubbers, hydrocolloid and silicone materials appear to be

excellent, while alginates are definitely inferior both in their inherent behavior and in

combination with the three die materials tested. The ability of the impression material to

register detail from the original die exceeded the reproduction capabilities of the gypsum

cast material tested. A difference was noted in the behavior of the stones tested in regard

to reproduction of small detail.

BERGMAN, JAN OLSSON, BERGMAN (1980)13 conducted a study to

determine the influence of disinfectants on the dimensional stability, surface detail and

accuracy of elastomeric impression materials. The results showed, in some cases, effect

of certain disinfectants during the impression material disinfection procedures. The shape

of specimen was built in Teflon mould. On its surface, spiral grooves were marked to

record the measurement variations. Each specimen was analyzed under the ZEISS

microscope under controlled humidity and temperature. A total of one hundred and

twenty specimens divided into groups of fifteen, were made for each type of material

(Permelastic Light, Regular and President Viscous Light, Regular, Heavy and Viscous

Reprosil Light, Regular and Sticky; Optosil and Xantopren, and Impregum). Specimens

from the control group were dipped in distilled water for one hour, then washed in

distilled water for 1 minute, dried in an air jet and measured. Then the specimens were

left on a plate-glass for 24 hours before measuring again. These measures were also made

for the other seven groups of immersions in seven different disinfectant solutions. 3


Page 7

levels of surface change were determined: 1. the visible change, 2. slight change of the

surface and 3. Significant change. Two observers classified the specimens with

agreement of 94%. This work showed that the differences found in linear dimensions of

all the materials studied are within the margin of measurement error for immersion times

of 1 hour and thereafter 24 hours.

MC’CABE (1981),14 conducted a study in which he immersed Silicones,

Polyether, Polysulfide, reversible hydrocolloid and irreversible hydrocolloid in solutions

of 1%Sodium Hypochlorite, 2% Alkaline Glutaraldehyde and 4% Formalin for 16

hours. The evaluation of the materials for dimensional stability showed that

1. Silicones can be disinfected by this method in any of the solutions.

2. Polysulfide showed better stability in a solution of 2% glutaraldehyde.

3. Polyether showed significant dimensional change in aqueous solutions of both

glutaraldehyde and formaldehyde.

4. Alginate did not change significantly only in solution of 1% sodium hypochlorite

RHODES et al. (1985), 15 studied the effects of glutaraldehyde based solutions

on commercially available elastomeric materials. The objective of this investigation was

to evaluate the effects of solutions with different pH on the physical properties of

polysulfide, silicone [addition and condensation] and polyether. The results indicated that

the times and dilutions tested did not cause significant changes in any of the tested

materials.


Page 8

SETCOS, J.C et al. (1985)16 studied the effects of 12 disinfectant solutions on

the linear dimension of the polyether Impregum. They made impressions of a metallic

standard model, then it was washed, shaken and placed under water for 15

minutes. Models were cast in stone after this time, except for the control group which

was built immediately after molding. Neither solution was capable of causing change in

material in the time tested, indicating this method of disinfection that can be used without

restrictions.

JOHANSEN, STACKHOUSE JR (1987)17 conducted a study to measure and

compare the linear dimensional change of elastomeric impression materials submitted to

immersion in solution of 2% glutaraldehyde. The authors concluded that polyether stay

stable on the bench, but expand when immersed in solution considerably. Polysulfide and

condensation silicone contract 0.3 to 0.4% during 16 hours of immersion, not showing

any significant difference from the control group.

WATKINSON (1988)18 studied the routine impression disinfection procedures in

40 Departments, 15 undergraduate schools / British graduate schools. Only in 15 of the

40 Departments use was made of disinfecting agents for impression disinfection, while in

18 departments no disinfection procedure was used. In the other seven, the impressions

were washed with water to reduce surface contamination.

TULLN, COMMET; MOON (1988)19 conducted a study to determine which

specific disinfectant solution should be used for immersion disinfection of the impression

materials; that caused least significant dimensional changes in impression. An acrylic

master model was constructed to represent half of the mandible from central incisor to


Page 9

second molar. Points of reference for the model were constructed of stainless steel. Trays

were made with individual relief of 2mm to 6 mm for elastomers and hydrocolloids. The

impression materials tested were Polysulfide, Polyether, Addition Silicone and

Alginate. After 15 minutes of immersion in solutions of Iodoform, Sodium Hypochlorite

or Neutral Glutaraldehyde, templates were washed, dried and poured immediately, except

for Polysulphides [waited 1 hour for pouring]. The impressions from control were

washed, dried and immediately poured without going through any kind of treatment.

After waiting an hour for the casts to set completely, the model was separated from the

mold and measured 5 times each, in an optical microscope with an accuracy of 0.0001

inch. Only four measures showed statistical significance of dimensional changes, though

these distances are not clinically relevant. For the author, a change of 0.31%, as found in

addition silicone and in alginate, when projected on a preparation of 5 mm, which means

only 15 microns in marginal adjustment of the crown. This is not significant compared to

25 microns required by the film of cement specified by the ADA.

JAMES A. COTTONE, et.al (1990)9 conducted a study to determine the efficacy

of disinfection / sterilization protocols recommended by manufacturers of impression

material. Minimum distortion of poly sulphide rubber base material occurs with 2% acid

glutaraldehyde, 0.5% or 1% sodium hypochlorite, or 0.1% povodine iodine and

concluded that none of impression manufactures had an appropriate, complete

disinfection protocol.

PEUTZFELDT et al.(1990)20 studied the effect of immersion in disinfectant

solution on the surface texture of two types of polyether, five types of silicones and three

types of irreversible hydrocolloids. The specimens were constructed with Plaster of Paris


Page 10

from a metal block with a rough surface. The casts poured from the control group were

stored at room temperature for 24 hours. The other impressions were immersed for one

hour in distilled water, chloramine 2%, 70% ethanol, chlorinated tri-sodium phosphate

4% and 2% glutaraldehyde. Followed over 24 hours, the grooves of the plaster models

were evaluated with a profilo-meter. Three of the five addition silicones showed no

change after treatment with disinfectant. In the seven remaining materials, reproduction

of detail was altered by some of the solutions tested. From this, the authors conclude that

disinfection causes reduced capacity for detail reproduction and in some cases improved

surface texture.

LANGENWALTER; AQUILINO; TURNER (1990)21 investigated the

dimensional stability of polysulfide, polyether and addition silicone from a stainless steel

model built according to no 19 specification of the ADA. The impressions were

immersed in a solution of 0.0075% Iodoform, 0.05% sodium hypochlorite and 2%

glutaraldehyde for 10 minutes. The results indicated that the disinfectants tested did not

cause a statistically significant change in the linear dimension of the impression

materials.

In 1990, MINAGI et al22 studying the effect of the solution glutaraldehyde on the

dimensional stability of hydrophilic silicones of various consistencies showed that

disinfection by immersion for the times of 10, 20, 30, 60 and 120 minutes at 20 ° c

caused slight expansion (0.03%) in tested materials. They also showed that this type of

solution can be used for disinfection of hydrophilic silicones.


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MATHYAS et al (1990).23 compared measurements of models poured from

impressions treated for 10 minutes under immersion or spray of solution of o-

phenylphenol, glutaraldehyde, sodium hypochlorite, phenol and formalin with those of

untreated impressions. All materials were stable during the various test conditions. There

was also no difference in the accuracy of models from the group treated by dipping

or spraying.

LAUB L.W ; SANDRIK (1990).24 determined the effect that the immersion of

impressions of elastomers in disinfectant solutions based on glutaraldehyde had on the

surface hardness characteristics of the plaster casts. Impressions of line patterns in a

marked block were made with Polyether (Permadyne, Impregum F), Addition Silicone

(Express, Permagum) and Condensation Silicone (elasticon). After polymerization in

water bath at 35 ° c the specimens were immersed in four kinds of solution of

glutaraldehyde (Cidex 7, Glutarex, Sterall, Sporicidin) for 10 minutes. The control group

was kept in ambient conditions and immersed in de-ionized water. The plaster models

were poured 1 hour after polymerization and subjected to verification of knoop hardness

24 hours later. The cast surface quality was assessed with the semi-electronic microscope

with increased magnification of 1500x. The difference in hardness was not significant

(p ≤ 0.01) for dry specimens of the control groups and de-ionized water and impressions

obtained from Impregum F, Express and Elasticon. The hardness of the gypsum casts in

the control group was greater. Casts obtained from Impregum F showed no significant

differences compared to the control group bodies immersed in water and the group

immersed in Sterall. There is a significant decrease of hardness after immersion in

glutarex, cidex and sporicidin.


Page 12

SAMARANAYAKE, HUNJAN; JENNINGS (1991)25 investigated the

contamination and persistence of oral flora on irreversible hydrocolloid and elastomeric

impressions. The first part of the study was innoculation of Streptococcus mutans,

Escherichia coli, Staphylococcus aureus and Candida albicans on the surface of two

types of elastomers (Addition Silicone - Provil and Polysulfide Permelastic) and two

types of Irreversible Hydrocolloids ( Kromopan Blueprint and Aseptic). Samples of the

impression materials were removed in the form disk 13 mm in diameter. After a period of

5 hours in culture, the microorganisms were counted. In the second part of the study, 21

impressions of edentulous and dentulous patients were taken and the count of bacteria

was estimated and reported. The results showed 2 to 5 times more retention of bacteria in

irreversible hydrocolloids compared with the surface of the elastomers. In all impression

materials the number of viable bacteria present after 5 hours, decreased 65% to 98%,

except in the hydrocolloid containing disinfectant in its constitution. This showed total

destruction of microorganisms in less than three minutes. Among the findings seen, the

microbial load of the impression is higher in dentate than in edentulous, and this charge is

reduced rapidly with time. However, this does not eliminate the need for compulsory

disinfection of impressions.

GERHARDT, WILLIAM (1991)26 three major factors should be considered

when the molds are disinfected: the behavior of impression materials, the stability of the

solution disinfectant and effectiveness of the disinfectant solution. His study found that

sodium hypochlorite used to disinfect dental impressions is stable. The results indicated

the interference of three factors on the stability namely time, the conditions of storage

and use.


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PHILLIPS (1993) 8 classified impression materials as inelastic and elastic. As

per this author elastomers in general, can be disinfected in several solutions provided that

the period of exposure to disinfectant is short. A prolonged immersion in solution can

promote measurable distortions in the impression, and certain agents can reduce the

surface hardness of the poured plaster model. The Polyethers are most likely to change

dimensionally, if the immersion time is longer than 10 minutes.

C.PETER OWEN et.al (1993)27 conducted a study on disinfection of impression

material to prevent viral cross contamination. The polyether impression material expands

when immersed in disinfectant solution for prolonged period so it is not a material choice

when sterilisation is required. He concluded that choice of suitable impression material is

limited by the long immersion time required for sterilization.

The behavior of condensation silicone, polyether, polysulfide and addition

silicone immersed in Sodium Hypochlorite, Glutaraldehyde, Povidone Iodine and Ethyl

Alcohol were studied by ODA; MATSUMOTO, SUMI (1995).28 His work showed that

polysulfide and condensation silicone contract over time, but this contraction decreases

when immersed in disinfectant. Addition silicone shows excellent dimensional

stability. However, hydrophilic addition silicone and polyether expand considerably

when immersed in disinfectant solution, especially in ethanol. The hydrophobic addition

silicone provides excellent dimensional stability in the absence or presence of

disinfectant.


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THOUATI et al (1996)29 showed the influence of three disinfectant solutions on

the dimensional stability of seven elastomers. The impression materials tested are Optosil

P / L Xantoprem Blue Zetaplus / Tixoflex, Provil P / Lcd Elite (High and Low Viscosity)

and Dense Eurogum X1 / X3 Fluid. These materials have been dispensed and mixed

according to the manufacturer's specifications in an environment with controlled

temperature using the technique of double impression. The impressions were subjected to

four different conditions including immersion for 30 minutes in a solution of Quaternary

Ammonium Amphoteric Agent 2% (Dentasept), immersion for 60 minutes in 10%

Formaldehyde (Gigasept), immersion for 30 minutes in Sodium Hypochlorite 5.25%

(Hypochlorite) and poured immediately without immersion (control). Their results

indicated a contraction of 0.07% to 0.51 in the materials that have not been subjected to

disinfectant action. Condensation silicones showed half of the Zetaplus, Optosil

accuracy. However, taking into account the contraction of material when it polymerizes,

these expansions become smaller in absolute values for all materials.

MARIA DEL PILAR RIOS, et.al. (1996)11 conducted a study to evaluate the

accuracy and stability of impression materials when treated with disinfectant solutions.

He concluded that high level disinfectant solutions that belong to different chemical

groups at different concentrations did not affect the accuracy and dimensional stability of

polyether and poly vinyl siloxane impression material for 30 or 60 min.

According to POULOS, ANTONOFF (1997)10 many impression materials are

dimensionally unstable when immersed in a solution. The possibility of distortion is the

cause of much concern, especially in hydrophilic material that can absorb liquid.

Glutaraldehyde solutions cause slight expansion in rubbery silicone hydrophilic materials


Page 15

after immersion, so it is the most compatible solution that could be used with this

material. Because of its gel structure, hydrocolloids undergo changes dimensionally

immediately after gelation. The immersion of this material may cause distortion. There

are two methods available for disinfecting irreversible hydrocolloid (alginate). They are:

1 - spraying with a disinfectant solution diluted according to manufacturer's instructions,

placing in a plastic sealing bag and letting it stand for the time recommended by the

manufacturer (usually 10 to 30 minutes), then removing the bag, washing in water current

at room temperature and pouring as usual . 2 - Replacing the water used for mixing

irreversible hydrocolloid (alginate) with a solution disinfectant (provided by

manufacturer) of 0.2% or 0.01 % Chlorhexidine Titratabe Iodine. This results in an

internal disinfection and allows the operator to pour the impression immediately. 3-

Reversible hydrocolloid is disinfected by washing after removal from the mouth and

submerged in a solution disinfectant, preferably for 30 minutes, then washing with water

at room temperature and poured immediately. "

JOHNSON et al (1998).30 showed in another study that Irreversible

Hydrocolloids, Polyethers and Addition Silicones can be disinfected by immersion;

however this led to decreased accuracy of impressions and plaster models that can be

clinically significant. Specific combinations of irreversible hydrocolloid and

disinfectants, as is the case with the Jeltrate-Iodoform and Palgaflex-Glutaraldehyde

yielded the higher precision usually obtained. The surface quality of casts and models

tested in Polyether and Addition Silicone groups if disinfected or not, was higher than

that in the Irreversible Hydrocolloid. However, the quality of surface models from

irreversible hydrocolloid was enhanced by immersing the impressions in Glucose-And


Page 16

Phenol-Glutaraldehyde. This work gave indirectly the dimensional change of impression

materials by measuring distances of several clinically relevant type IV plaster models

reproduced from a master model of resin that represented a mandibular dentulous

arch. This model contained master stainless steel pins in each first molar occlusal surface

and lingual surface of the central incisors that served as reference for taking

measurements. Still, the area of a right pre-molar was receiving a modified stainless steel

pin with 12 degrees of convergence cervical-occlusal, mimicking a premolar prepared to

receive a full crown. The impression materials that were tested are alginates

(Palgaflex,Jeltrate), polyether (Impregum F) and addition silicone (President). The

disinfectants used were Iodoform (Biocide), glyco-glutaraldehyde (Impresept of) and

phenol-glutaraldehyde (Sporicidin). Ten minutes after the setting time, the impressions

were removed from master model and rinsed for 10 seconds. They were then immersed in

solution disinfectant for 10 minutes, while the control remained on the bench for this

same time. As a result, this study demonstrated that with polyether impressions, dies

generated are smaller in size than the original preparation, both from disinfected and not

disinfected impressions. Although the addition silicones have shown a significantly

higher degree of accuracy compared to the polyether, this difference is not clinically

relevant.

XAVIER LEPE et al (2002).31 There is an ongoing effort by dental

manufacturers to create impression materials with improved wetting properties. They

compared wettability, imbibitions and mass change of various recently introduced mixed

low-viscosity addition silicone and polyether materials before and after immersion


Page 17

disinfection. Within the limitations of this study imbibitions for the 2 polyether materials

were significantly higher (p<.001). Polyether materials lost significantly more (0.6% to

0.8%) and Aquasil LV gained significantly more (0.6%) mass in air.

MOREIRA DA SILVA et al (2004)32 conducted a study on effect of disinfectant

solutions on stability of impression materials. He concluded that there was no statistically

significant difference between the dimensional stability of silicone impressions immersed

in the 1% sodium hypochlorite solution or in 2% glutaraldehyde solution.

WALKER MP et al (2005)33 evaluated and compared the dimensional accuracy

and surface detail reproduction of two hydrophilic vinyl polysiloxane and two polyether

impression materials when used under dry and moist conditions. The surface detail

evaluation using criteria similar to ADA specification 19 indicated that moisture had a

significant effect on detail reproduction of vinyl polysiloxane materials. Under dry

conditions, all materials exhibited satisfactory detail reproduction 100% of the time;

however, under moist conditions, only 29% of PVS impressions produced satisfactory

detail reproduction, while 100% of the polyether impressions still met the criteria for

surface detail. Thus, although moisture may not adversely affect the dimensional

accuracy of either polyether or hydrophilic vinyl polysiloxane material, evidence

suggested that Polyether material is more likely to produce impressions with superior

surface detail reproduction in the presence of moisture.

CHANDUR P.K., WADHWANI et al (2005)34 conducted a study to assess the

accuracy of 2 types of fast setting impression materials when disinfected with acid

glutaraldehyde. The impression materials evaluated demonstrated sufficient accuracy.


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Immersion disinfection did not adversely affect the accuracy of any of the impression

materials. The working cast and working dies from regular and fast setting polyether

demonstrated an increase in all dimensions when compared to the master model and

stainless steel complete crown preparation. The working casts from the fast set VPS were

larger than the master model, whereas working dies showed a reduction in mesio-distal

dimension and height compared to the stainless steel complete crown preparation. The

new fast setting polyether and VPS materials demonstrated dimensional accuracy

equivalent to a traditional polyether.

TATSUO ENDO et al (2006), 35 worked on the dimensional accuracy of a new

polyether impression material. Their study showed that the vinyl polysiloxane material is

reasonably dimensionally stable during 24 hours of storage, irrespective of the

surrounding humidity. Impressions from polyether should preferably be cast with stone

within a few hours after impression making. During 24 hours of storage, the materials

show significantly increased shrinkage. Although polyether impressions show relatively

high shrinkage after 1 hour, they demonstrate acceptable dimensional accuracy after 24

hours only, when the impressions are not exposed to long-term relative humidity above

50%.

MARY P. WALKER et al (2007),36 investigated the effect of disinfection on

surface quality and dimensional stability of more recent, reformulated vinyl polysiloxane

and polyether materials and concluded that polyether significantly expanded following

disinfection with NaOCl or dual phenol, while there was no significant change in vinyl

polysiloxane dimensional accuracy following disinfection. Both non-disinfected and

disinfected vinyl polysiloxane and poly ether impressions exhibited increasing shrinkage


Page 19

over the period of time. There was a significant adverse effect on the surface quality of

poly ether with increasing exposure to NaOCl. Although disinfection does not appear to

adversely affect dimensional accuracy/stability of the more recent VPS and PE materials,

not all disinfectant solutions produce optimal impression surface quality with the newly

formulated poly ether.

SOO-HWA KIM et al. (2007), 37 conducted studies to evaluate the wettability of

the surface of the impression materials. The polymerization process and time might affect

the wettability of impression materials. The additional silicone impression material

showed distinct decrease of initial hydrophobicity to very hydrophobic levels, during and

after working time. He concluded that contact angle of dental impression materials is

effected by amount of time elapsed after mixing and disinfection and the hydrophobicity

of impression materials used should be considered when taking impressions and making

gypsum models.

OSAMA AL-JABRAH et al (2007), 38 stated that impression materials may act

as a vehicle for the transfer of microorganisms, and disinfecting them can completely

eliminate microorganisms carried by impressions.

HANDAN YILMAZ et al (2007),39 conducted a study on effect of disinfectants

on the dimensional stability of polyether impression materials and concluded that the

disinfectants tested for 10 min caused no significant dimensional change in polyether

material compared to control group.

DC JAGGER et al (2007). 40 studied the effect of range of disinfectants on

dimensional accuracy of some impression materials and concluded that for all the


Page 20

materials the changes in dimensions were small. These changes however are of no

clinical significance for fixed prosthodontic procedures.

DARIO MELILLI et al (2008). 41 conducted a study on effect of immersion

disinfectant procedures on dimensional stability of elastomeric impression material and

concluded that the dimensional change of all materials was within ADA specifications.

E. KOTSIOMATI et al (2008) 42 conducted a study on accuracy and stability of

impression materials subjected to chemical disinfection and concluded that polyethers

can be effectively disinfected by spraying; hydrophobic elastomers can be safely

immersed in disinfectants.

JENS JOHANNES BOCK ET AL (2008)43 conducted a study on influence of

different disinfectants on primary impression materials and concluded that casts from

silicone impressions were more accurate. Different disinfectant methods have only

marginal influence on dimensional stability and surface quality of dental casts.

WALA M. AMIN, et al (2009)44 concluded that sodium hypochlorite,

glutaraldehyde affected addition silicones very marginally. Of all the disinfectants

employed 0.5% sodium hypochlorite effected the least changes in the dimensions of

impression materials. Use of 0.5% sodium hypochlorite is recommended for 10 min

disinfection.

DIDEM ATABEK , et al (2009)45 evaluate the time dependent effects of

disinfection agents on impression materials and concluded that to rinse impression

materials only with water before casting is not an effective method for preventing cross-

contamination. Such a short time of 3 min. application of either 7.5% Povidone iodine or


Page 21

1% sodium hypochlorite was found sufficient for disinfecting impressions. In routine

dental practice the disinfection process of impression material in short period of 3

minutes can be practical, easy and effective method for clinicians. Disinfecting

impressions in a short period of 3 minutes as being a very practical method will stop

cross contamination and spreading of the infections in dental profession.

STOBER T, JOHNSON GH, SCHMITTER M. (2010)46 conducted a study to

evaluate accuracy of the newly formulated vinyl siloxanether elastomeric impression

material. Impressions were made from a modified dentoform master model containing a

simulated crown preparation. Dimensional changes between the master model and

working casts were assessed. VSE impressions demonstrated acceptable accuracy for

clinical use with immersion disinfection, since the results for VSE were comparable to

the results for PE and VPS materials, and the differences as compared to the master

model were small.

J. BUSTOS et al (2010)47 conducted a microbiological and SEM study on effect

of immersion disinfection with 0.5% sodium hypochlorite and 2% glutaraldehyde on

silicone and concluded that immersion in o.5% NaOCl and 2% glutaraldehyde for 10 min

completely eliminated bacteria in impressions. Immersion for 5-10 min significantly

inhibited bacterial growth in silicone impression materials. In SEM study immersion in

both disinfectants did not significantly affect surface quality.

N. ALMORTADI et al (2010)48 conducted a survey on disinfection of dental

impression and its compliance to accepted standards and concluded that a wide range of

solutions at different dilutions of same product was used by dentists to disinfect

impressions. 37.2% rinsed the impression with water, 2.6% always brushed debris away


Page 22

before disinfection and 24.7% informed laboratory of disinfection. Irrespective of the

disinfection status of the received impression, 50% of technicians disinfected

impressions, 64.7% were confident that impressions received by them are disinfected by

dentists.

K. SAMRA et al (2010)49 conducted a comparative study to evaluate efficacy of

different disinfectant systems on addition silicone materials of Indian and international

origin and concluded that glutaraldehyde and hypochlorite were effective in reducing the

microbial load, persistence. Carriage of microbial load was twice in alginate impressions

as compared to addition silicone group.

CINTIA LARA ODA CARVALHAL et al (2011)50 studied the influence of

immersion period in two disinfectant solutions on dimensional change of elastomeric

impression materials and concluded that with the exception of poly di-methyl siloxane for

5 or 10 min, there were no difference between disinfectant solutions. Immersion time

influenced dimensional change of different impression materials. Up to 20 min there was

no significant dimensional change for impression materials.

EMADE WADIE ESTAFANOUS et al (2012)51 evaluated disinfection of

bacterially contaminated hydrophilic polyvinyl siloxane and polyether impressions and

concluded that no bacterial growth was found on any stone casts resulting from

disinfected impression materials and no bacterial growth on selective media from stone

casts disinfected. Ten minutes either with spray or immersion disinfection is an effective

time to disinfect the impression materials. Disinfectants investigated in this study will

effectively disinfect PVS and polyether impression material.


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RAVI KUMAR R et al (2012) 52 evaluated the effects of chemical disinfection,

autoclaving and microwave sterilization on five elastomers and concluded that sterilizing

elastomers by autoclave and microwave is associated with mild linear dimensional

changes. Although statistically significant dimensional changes were observed, it is

important to note that the dimensional changes were less than 0.3%, which is well within

the ADA recommended dimensional change (< 0.5%). Therefore elastomeric material

can be safely sterilized using autoclave and micro wave energy because chemical

disinfection alone is less lethal and does not eliminate all bacterial forms.

4 review of literature

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