advances in the mechanical properties of resin composites , associated with improvement 
 in adhesive systems , have favored the clinical application of these restorative 
 materials , especially in posterior teeth . in spite of these improvements ,
the mechanical 
 properties of these materials vary considerably because of the differences in the 
 composition of the organic matrix as well as the type , size , and packing of the 
 inorganic fillers12 .
the introduction of new or 
 modified dental products on the market requires the assurance that these materials can 
 be stored for an extended period without any decrease in their performance that may 
 affect safety and efficacy14 .
shelf life is 
 defined as the term or period during which a commodity remains suitable for the intended 
 use9 . on the other hand ,
expiration date is 
 the termination of shelf life , after which a percentage of the product , i.e. , medical 
 devices , may no longer function as originally intended . in order to determine whether a 
 certain product requires a shelf life and assign an expiration date , there are a number 
 of different parameters that must be considered13 . in this way
, this product must be analyzed to determine if it is susceptible 
 to degradation that would lead to functional failure and to determine the level of risk 
 that the failure would present9 .
accelerated aging protocols are generally applied to new products to provide 
 experimental data in order to estimate their clinical performance and shelf life claims . 
 in these protocols ,
products are subjected to stresses that are more severe or more 
 frequently applied than normal environmental or operational stresses for a shorter 
 time14 .
studies on accelerated aging combined 
 with basic stability information on the components ( functional chemical groups organized 
 in diverse ways crystalline or amorphous - along with additives such as antioxidants , 
 inorganic fillers , plasticizers , colorants , and processing aids14 ) may be used to support tentative expiration dates5 .
these variations , combined with the different 
 protocols of clinical applications and oral environment , determine the degradation 
 process14 . in a previous study6 ,
it was pointed out that the material condition 
 may affect the propagation stage ( second stage of the polymerization reaction attributed 
 to the propagating radical ) , in which the free radicals react successively with monomers 
 to form a three - dimensional network .
clinicians tend to store the restorative materials at low temperatures , especially the 
 resin composites , in order to " prolong " their shelf life15 .
however , these cooled restorative materials are used immediately after 
 being removed from the refrigerator10 . in 
 addition , their manipulative properties are modified , considering that some of the 
 composites are too sticky and tend to flow less at lower temperatures . a consensus that 
 the rheological properties of resin - composites play an important role in terms of 
 restoration longevity exists17 .
the viscosity of 
 a resin - composite is directly related to its handling characteristics ( placement and 
 shaping on the restored site)19 . in spite of the 
 composite stickiness , manufacturers have modified the composite viscosity , as this 
 manipulative characteristic may allow the formation of macroscopic spaces and 
 microscopic porosities in the restorations23 . 

clinically , an unpolymerized resin - composite is applied and 
 exposed while in a varied viscous state and variations in the conversion values can be 
 reached as the rheological properties of composites influence the radical mobility , 
 depending on the viscosity6 . in this way ,
no 
 objective criteria to support the indication of high viscous composites or " compactable " 
 composites have been provided16 . in addition , the 
 influence of the energy dose as a function of the material condition needs further 
 investigation . as the kinetics of polymerization
is dependent upon the energy dose , it 
 could be expected that the longer light exposure time would somehow allow a higher end 
 conversion7 , irrespective of the material 
 condition .
this study evaluated the mechanical properties ( flexural strength and flexural modulus ) 
 of different classifications of composites indicated for posterior application as 
 functions of the storage condition ( room temperature , aged , oven , refrigerator , and 
 freezer ) and the energy dose .
the following research hypotheses were tested : ( 1 ) the 
 storage temperature can influence the flexural strength of the composites tested ; ( 2 ) 
 the flexural modulus of the composites stored at different temperatures will be inferior 
 to that observed at room temperature ; ( 3 ) the energy dose influences the mechanical 
 properties of the composites , irrespective of the storage temperature .
in this in vitro study , mechanical characterizations were performed 
 according to the factors : ( 1 ) composites , at three levels : filtek p60 ( p60 ) , filtek 
 z350xt ( xt ) , and filtek silorane ( fs ) ; and ( 2 ) material conditions , at five levels : i 
 - control ( room temperature - rt , 22c ) , ii - accelerated aged composites ( aa ) , iii - 
 oven at 37c for 24 h ( ov ) , iv - refrigerator at 2c for 24 h ( rf ) , and v - freezer 
 at -15c for 24 h ( fz ) ; ( 3 ) energy dose , at two levels : i - 24 j / cm , ii - 
 48 j / cm .
thirty experimental groups were obtained of the product 
 among the combinations of the factors under study .
bisgma : bisphenol - glycidyl - methacrylate ; udma : urethane - dimethacrylate ; 
 bisema : bisphenol - a - ethoxy dimethacrylate ; tegdma : triethyleneglycol 
 dimethacrylate ; pegdma : poly(ethylene glycol ) dimethacrylate manufacturer 's information ( 3 m espe , st .
paul , mn , usa ) bis-3,4-epoxycyclohexylethylphenyl - methylsilane and 
 3,4-epoxycyclohexylcyclopolymethylsiloxane note : the brand name filtek silorane is used in other countries as filtek ls 
 and filtek p90 the composites underwent a simplified protocol for accelerated aging ( also called the 
 " 10-degree rule " ) according to the collision theory based on the arrhenius model .
the 
 composite syringes were stored at 37c in an oven for 12 weeks . according to 
 clark5 ( 1991 ) ,
the accelerated aging 
 protocol can be calculated by means of a mathematical formula , as follows : 
 r = accelerated aging rate ; 
 rt = room temperature ( 22c ) ; 
 et = elevated temperature ( 37c ) ; 
 q10 = reaction rate coefficient ( 2 ) . according to this protocol , for each 10c increase above the room temperature , the 
 reaction rate doubles5 . in this way , as the 
 rt was equivalent to 22c , r corresponds to 
 2 ( 37 - 22=15 ; 15/10=1.5 ) .
thus , the accelerated aging rate was 
 based on the increase of 15c in the storage temperature , which is 1.5 squared 
 ( r=1.5=2.83 ) .
finally , in order to estimate the aging 
 time equivalent to that which would occur at room temperature , r was 
 multiplied by the storage time ( 12x2.83 ) , which represents approximately 9 months of 
 aging .
it is important to mention that the same lot numbers were used for the 
 material condition levels of " room temperature " and " aged " .
in addition , care was 
 taken to ensure that the composites were not expired after the accelerated aging 
 protocol ( simulating a 9-month shelf life)7 .
after the storage time respective to the experimental groups had elapsed , the 
 syringes were kept untouched until room temperature was reached . an infrared 
 thermometer (
general tools & instruments , irt-206 gun - style infrared thermometer , 
 new york , ny , usa ) was used to evaluate the syringe temperatures .
the composites were 
 applied to a teflon mold ( 822 mm ) , positioned over a polyester strip ( n=10 ) .
after 
 filling the mold to excess , the material surface was covered with a mylar strip and a 
 glass slide and compressed to extrude excess material .
all restorative materials were 
 photoactivated using an led light - curing unit ( bluephase , ivoclar vivadent , schaan , 
 liechtenstein ) with a power density of 1200 mw / cm for 20 s ( energy dose 
 of 24 j / cm ) or for 40 s ( energy dose of 48 j / cm ) . prior to 
 testing and throughout the experiment ,
the power density was monitored using a 
 handheld radiometer ( model 100 , demetron research corp . ,
all of 
 the composites selected were shade a3 ( an exception was xt : shade a3b ) .
specimens 
 were then stored in distilled water at 37c for 24 h. prior to the test , the specimen dimensions were measured using a digital caliper 
 ( digimatic caliper cd , mitutoyo , japan ) .
the three - point bending test was carried out 
 in a universal testing machine ( instron model 3342 , instron corp . ,
canton , ma , usa ) 
 at 0.5 mm / min and 5 mm span between supports .
s ( s ) was calculated as follows : flexural modulus ( e ) was calculated by : where f is the maximum strength in n ; l the 
 distance between the rests ; b the width of the specimen ; 
 h the height of the specimen ; and f / y the slope of the linear 
 part of the stress - strain curve . statistical analysis of s and 
 e was performed with three - way anova and tukey 
 post - hoc test (  = 5 % ) .
in this in vitro study , mechanical characterizations were performed 
 according to the factors : ( 1 ) composites , at three levels : filtek p60 ( p60 ) , filtek 
 z350xt ( xt ) , and filtek silorane ( fs ) ; and ( 2 ) material conditions , at five levels : i 
 - control ( room temperature - rt , 22c ) , ii - accelerated aged composites ( aa ) , iii - 
 oven at 37c for 24 h ( ov ) , iv - refrigerator at 2c for 24 h ( rf ) , and v - freezer 
 at -15c for 24 h ( fz ) ; ( 3 ) energy dose , at two levels : i - 24 j / cm , ii - 
 48 j / cm .
thirty experimental groups were obtained of the product 
 among the combinations of the factors under study .
bisgma : bisphenol - glycidyl - methacrylate ; udma : urethane - dimethacrylate ; 
 bisema : bisphenol - a - ethoxy dimethacrylate ; tegdma : triethyleneglycol 
 dimethacrylate ; pegdma : poly(ethylene glycol ) dimethacrylate manufacturer 's information ( 3 m espe , st .
paul , mn , usa ) bis-3,4-epoxycyclohexylethylphenyl - methylsilane and 
 3,4-epoxycyclohexylcyclopolymethylsiloxane note : the brand name filtek silorane is used in other countries as filtek ls 
 and filtek p90
the composites underwent a simplified protocol for accelerated aging ( also called the 
 " 10-degree rule " ) according to the collision theory based on the arrhenius model .
the 
 composite syringes were stored at 37c in an oven for 12 weeks . according to 
 clark5 ( 1991 ) ,
the accelerated aging 
 protocol can be calculated by means of a mathematical formula , as follows : 
 r = accelerated aging rate ; 
 rt = room temperature ( 22c ) ; 
 et = elevated temperature ( 37c ) ; 
 q10 = reaction rate coefficient ( 2 ) . according to this protocol , for each 10c increase above the room temperature , the 
 reaction rate doubles5 . in this way , as the 
 rt was equivalent to 22c , r corresponds to 
 2 ( 37 - 22=15 ; 15/10=1.5 ) .
thus , the accelerated aging rate was 
 based on the increase of 15c in the storage temperature , which is 1.5 squared 
 ( r=1.5=2.83 ) .
finally , in order to estimate the aging 
 time equivalent to that which would occur at room temperature , r was 
 multiplied by the storage time ( 12x2.83 ) , which represents approximately 9 months of 
 aging .
it is important to mention that the same lot numbers were used for the 
 material condition levels of " room temperature " and " aged " .
in addition , care was 
 taken to ensure that the composites were not expired after the accelerated aging 
 protocol ( simulating a 9-month shelf life)7 .
after the storage time respective to the experimental groups had elapsed , the 
 syringes were kept untouched until room temperature was reached . an infrared 
 thermometer ( general tools & instruments , irt-206 gun - style infrared thermometer , 
 new york , ny , usa ) was used to evaluate the syringe temperatures .
the composites were 
 applied to a teflon mold ( 822 mm ) , positioned over a polyester strip ( n=10 ) .
after 
 filling the mold to excess , the material surface was covered with a mylar strip and a 
 glass slide and compressed to extrude excess material .
all restorative materials were 
 photoactivated using an led light - curing unit ( bluephase , ivoclar vivadent , schaan , 
 liechtenstein ) with a power density of 1200 mw / cm for 20 s ( energy dose 
 of 24 j / cm ) or for 40 s ( energy dose of 48 j / cm ) . prior to 
 testing and throughout the experiment ,
the power density was monitored using a 
 handheld radiometer ( model 100 , demetron research corp . ,
all of 
 the composites selected were shade a3 ( an exception was xt : shade a3b ) .
prior to the test , the specimen dimensions were measured using a digital caliper 
 ( digimatic caliper cd , mitutoyo , japan ) .
the three - point bending test was carried out 
 in a universal testing machine ( instron model 3342 , instron corp . ,
canton , ma , usa ) 
 at 0.5 mm / min and 5 mm span between supports .
s ( s ) was calculated as follows : flexural modulus ( e ) was calculated by : where f is the maximum strength in n ; l the 
 distance between the rests ; b the width of the specimen ; 
 h the height of the specimen ; and f / y the slope of the linear 
 part of the stress - strain curve . statistical analysis of s and 
 e was performed with three - way anova and tukey 
 post - hoc test (  = 5 % ) .

 figure 3 shows data of s 
 regarding the three factors : composite x syringe storage condition x energy dose .
the highest s mean was noted for p60 aa ( 329.2 mpa ) , and 
 the lowest for z250 ov ( 117.3 mpa ) .
the interaction between the factors " composites " and 
 " material condition " was significant .
however , the factor " dose " and the triple 
 interaction among the factors were not significant .
all of the composites exhibited 
 statistically equivalent s means at room temperature ( rt ) and freezer 
 ( fz ) storage ( p>0.05 ) .
the s means of p60 were not influenced by the 
 storage at lower temperatures ( rf and fz ) , whereas for the silorane composite 
 s mean significantly decreased ( p<0.05 ) .
on the other hand , only 
 the storage at fz significantly decreased s means of xt ; the 
 s mean was not influenced by the rf storage in comparison to that at 
 rt ( p>0.05 ) .
all the composites exhibited significantly decreased in the 
 s means when the syringes were stored in the oven at 37c for 24 h 
 compared to that of at rt ( p<0.05 ) . on the other hand , the simplified protocol of 
 accelerated aging led to a significant increase in the s means for p60 
 and for filtek silorane ( p<0.05 ) .
mean values followed by different capital letters in row and small letters in 
 column : significant ( p<0.05 ) ( ): standard deviation mean values followed by different capital letters in row and small letters in 
 column : significant ( p<0.05 ) ( ): standard deviation 
 figure 4 shows the data of e 
 regarding the three factors : composite x syringe storage condition x energy dose .
the 
 highest e mean was noted for p60 fz ( 21.5 gpa ) and the lowest for xt ov 
 ( 13.3 gpa ) .
the interaction between the factors " composites " and 
 " material condition " was significant . the factor " dose " and the triple interaction among 
 the factors were not significant .
the factor " storage condition " produced no effect in 
 the e means of the silorane composite ( p>0.05 ) . for p60 and xt , 
 storage at ov
significantly decreased the e means , whereas the storage 
 at fz significantly increased the flexural modulus ( p<0.05 ) .
although the composites tested presented equivalent s means at room 
 temperature , the results were material - dependent when considering the different storage 
 conditions .
the simplified protocol of accelerated aging produced an increase in s 
 for the silorane composite whereas all of the other conditions ( oven , refrigerator , and 
 freezer for 24 h ) produced a significant reduction in this mechanical parameter .
on the 
 other hand , filtek p60 was not influenced by neither of the two lower temperatures 
 whereas filtek z350xt showed a significant reduction in s only when 
 stored at the freezer at 37c for 24 h. aging the filtek p60 produced a significant 
 increase in s. the composite filtek z350xt was the only composite not 
 influenced by the simplified protocol of accelerated aging . storing all of the 
 composites in the
oven produced a significant reduction in s. thus , the 
 first research hypothesis raised in the present study was upheld by the experimental 
 data as the storage temperature influences the flexural strength of the composites 
 tested .
the simplified approach for accelerated aging used in the present study was based on 
 conducting testing at a single accelerated temperature and then employing the rule 
 stating that the rate of a chemical reaction will increase by a factor q10 
 ( usually of 2 ) , which represents a doubling of the reaction rate for every 10c increase 
 in temperature14 .
this type of conservative 
 relationship is indicated for a variety of medical polymers that have been previously 
 characterized14 .
the degradation may be 
 primarily chemical - a combination of effects arising from oxidative chain scission , 
 oxidation hydrolysis , changes in crystallinity , and other factors that may be 
 environmentally dependent11 . chemical 
 crosslinking links molecules , while crystallinity and fillers introduce physical 
 limitations to monomer mobility4 . under these 
 variations ,
the rate of radical propagation eventually becomes diffusion - limited and the 
 polymerization rate decelerates , often providing only a limited conversion even in the 
 presence of an unreacted monomer and a population of radicals27 . in this way
, the crosslinking will be restricted by the 
 molecular response , depending on the storage temperature , since the degree of freedom 
 for monomer motions is reduced as the these monomers become irreversibly linked .
this 
 was particularly true in the accelerated aging composites as significant variations in 
 the flexural strength occurred in comparison to that at room temperature ( table 1 ) .
in contrast to those results noted after the accelerated aging protocol , in which the 
 s means increased , the s means obtained after 
 storage in the oven at 37c for 24 h significantly decreased for all of the tested 
 composites .
one would argue that an enhanced flexural strength would be obtained after 
 the storage in the oven at 37c as the result of an increased conversion given by 
 temperature - derived mobility of polymeric chains and consequent entrapped radical 
 engagement2 .
therefore , it is reasonable to 
 infer that the composites underwent a chemical degradation at shorter storage time ( 24 
 h ) before a change in the crystallinity would occur throughout the 12-week storage at 
 the same temperature ( aging protocol ) .
it could be argued that , by significantly 
 increasing the flexural strength after aging the composite syringes of filtek p60 and 
 filtek silorane would provide better clinical performance .
conversely , the increased 
 flexural strength may not represent improved mechanical properties , despite the 
 equivalence in terms of flexural modulus when compared to that of the means at room 
 temperature . in this way , it was clear that these contradictory results when comparing 
 shorter and longer storages in the oven at 37c have in common the fact that both 
 storage conditions interfere in the composite stability .
it is important to highlight 
 that the mechanical properties of composites tested depend on the properties of their 
 constituent materials25 .
thus , when comparing the 
 different composites , the large ranges in the s means were due to the 
 different classifications in the composite formulations , although all tested materials 
 are indicated for restoring posterior teeth .
filtek silorane is filled with a 
 combination of fine quartz particles and radiopaque yttrium fluoride , being classified 
 as a microhybrid resin composite .
the filler in filtek p60 is zirconia / silica in a 
 concentration of 83.0% by weight , classified as a hybrid composite .
filtek z350xt is a 
 nanofilled composite with 72.5% of fillers . as these materials are essentially polymeric 
 in nature , their laboratorial and clinical performances
are related to the rate of 
 degradation of their inherent structure and configuration over time .
in contrast to 
 methacrylate - base composites , the siloranebased composite contains cationic ring - opening 
 monomers , which represent a compensating mechanism for shrinkage stress achieved during 
 polymerization30 .
this resin composite combines two main advantages : low 
 polymerization shrinkage , due to the ring - opening oxirane , and an increased 
 hydrophobicity due to the siloxane compound .
the silorane - based composite revealed a 
 decreased water sorption , solubility , and associated diffusion coefficient compared to 
 those observed when methacrylate - based composites were tested24 .
the elastic modulus of low - shrinking composites and methacrylate - based composite was 
 recently reported as being similar , despite differences in the formulation , even though 
 the silorane composite has higher molecular weight and higher filler content29 . in another study
, it was also revealed that the 
 silorane material presents relatively higher flexural strength / modulus and fracture 
 toughness but relatively lower compressive strength and hardness than some 
 methacrylate - based restorative materials20 . in 
 the present study ,
no significance was noted among the composites in terms of 
 e at room temperature .
in addition , none of the composites had the 
 means of flexural modulus affected by the accelerated aging protocol .
different from 
 that observed for flexural strength , all of the storage conditions produced no effect on 
 e of the silorane composite . on the other hand ,
filtek p60 and 
 filtek z350xt were affected by storage in the oven at 37c for 24 h , significantly 
 decreasing e , whereas the storage in the freezer significantly 
 increased e ( p<0.05 ) . in this way , the second research hypothesis , 
 that the flexural modulus of the composites stored at different temperatures will be 
 inferior to that observed at room temperature , was also rejected . in spite of the similarity in terms of the flexural modulus ,
the flexural strength of 
 the filtek silorane was the only composite negatively influenced by both the lower 
 temperatures and storage conditions .
the reasons that explain the lower flexural 
 strength means rely on the fact that the silorane monomer presents a polymerization 
 reaction with a slow onset28 .
in addition , the 
 lower temperatures may impact the initial activation energy necessary to form the 
 activated complex , which represents the first two stages of the composite polymerization 
 - initiation and activation3 .
this somehow leads 
 to a more reduced extent of the composite monomer conversion that may impact the quality 
 of the polymerization process26 .
resin conversion 
 should be usually optimized in order to resist deterioration of mechanical and chemical 
 properties ; strength , hardness , stiffness , and wear resistance .
even the exposure of a 
 48 j / cm energy dose was not sufficient to compensate the impact on the 
 polymerization process . in this way ,
based on the results of the present study , it is 
 not recommended to store filtek silorane at low temperatures .
it has been advocated that refrigerated syringe composites should be warmed to at least 
 room temperature before clinical application as this procedure might disrupt the 
 material characteristics15 .
it is important to 
 point out that the composite syringes underwent the temperature treatment and not the 
 polymerized specimens .
in addition , the specimens were produced only when the syringes 
 were at room temperature .
although dental manufacturers recommend that composites be 
 stored at room temperature10 , all of the 
 variables that include storage temperature and transportation conditions are not under 
 control .
the effect of these variables over the composite clinical performance can be 
 minimized if properly considered .
these variables can have an effect in a way that may 
 adversely affect the composite safety or performance18 .
temperature variations , relative humidity , ventilation , visible light and 
 other radiation , vibration , shock , temperature , and humidity are other important factors 
 to be considered , especially when a dental product is shipped between various climatic 
 zones22 . according to clark5 ( 1991 ) , depending on the shipping or storage 
 conditions , a breakage in a certain medical device , a failure of the barrier properties 
 of a sterile package or degeneration of the device itself may occur . in this way
, the 
 question as to how new the dental products available to the clinicians are remains 
 unanswered .
the third research hypothesis , which anticipated that the energy dose influences in the 
 mechanical properties of the composites , irrespective of the storage temperature , was 
 rejected . according to the statistical analysis ,
the factor " dose " and the triple 
 interaction among the factors were not significant for both the parameters tested .
a 
 reasonable explanation was that , in the present study , a 24 j/ cm energy 
 dose was sufficient to guarantee the composite polymerization of 2-mm thick specimens . 

clinically , it would be important to obtain well polymerized composites with enhanced 
 mechanical properties .
on the other hand , an energy dose of 48 j / cm should 
 be used with caution by clinicians considering the increase in the polymerization stress 
 generated when higher energy doses are applied .
in addition , the specimens exposed to a 
 low energy dose were stored at 37c for 24 h after photoactivation , and this fact may 
 allow an increased monomer conversion and enhanced mechanical properties similar to that 
 of obtained when a higher energy dose was applied21 . in a previous study7 , it was 
 pointed out that the energy dose associated with the bonding approach are determinant 
 factors in terms of the presence of internal gaps for both the methacrylate - based 
 composite and for the silorane - based one .
the present study deals with a clinical relevant issue as the syringe storage conditions 
 tested influenced the mechanical properties of different classifications of resin 
 composites .
storage as a function of the temperature proved to influence mostly the 
 composite flexural strength , possibly due to changes in the chemical stability and/or 
 crystallinity ( especially at higher temperatures ) of the composites and also due to the 
 impact of the quality of the polymerization process ( lower temperatures ) .
although the 
 dental manufacturers may not be able to control all of the variables like the storage 
 temperature and the transportation conditions , their effect on the composite clinical 
 performance can be minimized if properly considered by the clinicians8 .
extrapolations to clinically support and validate 
 the results using different resin - composite categories and filler contents need to be 
 done with caution since future studies are required to evaluate the performance of these 
 composites .
within the limitations of this study , the following can be concluded : the storage condition influences the flexural strength and the flexural modulus of the 
 composites in comparison to that observed at room temperature .
the energy dose does not influence the mechanical properties , irrespective of the 
 storage condition .
the aging protocol improves the flexural strength of filtek p60 and filtek silorane , 
 whereas storage in the oven at 37c for 24 h impacts the same parameter for all of the 
 composites tested .
it seems that the silorane composite should not be stored at lower temperatures , whereas 
 the filtek p60 is not impacted by these temperatures .
 objective : to investigate the mechanical properties of different classifications of 
 composites indicated for posterior application as functions of the storage 
 condition and of the energy dose.material and methods : specimens ( 8x2x2 mm ) were obtained according to the factors : i ) composites ( 3 m 
 espe ) : filtek p60 , filtek z350xt , and filtek silorane ; ii ) syringe storage 
 conditions : room temperature , aged , oven , refrigerator , and freezer ; and iii ) 
 energy dose : 24 j / cm2 and 48 j / cm2 . 
 after photoactivation , 
 the specimens were stored at 37c for 24 h. after storage , a three - point bending 
 test was carried out in a universal testing machine at 0.5 mm / min . 
 flexural 
 strength ( s ) and flexural modulus ( e ) were calculated . 
 data were analyzed by 
 three - way anova and tukey 's test ( =0.05).results : different storage conditions significantly affected the silorane composite for s ; 
 conversely , no effects were noted in terms of e. the accelerated aging protocol 
 significantly increased the s of filtek p60 and filtek silorane , whereas storage 
 in the oven significantly decreased the s for all of the composites tested . 
 filtek 
 p60 was the only composite not affected by the lower storage temperatures tested 
 for s , whereas for the silorane this parameter was impacted at the same 
 conditions . 
 the factor " dose " was not statistically significant.conclusions:the syringe storage at different temperature conditions proved to influence mostly 
 the flexural strength , a clinically important characteristic considering the 
 posterior indication of the materials tested . 
 the silorane composite should not be 
 stored at lower temperatures . 