Please explain why distance is not effect to experimental results in this research

1. In your presentation, why did you concluded that the tip of the light-curing unit should be placed closest to gain high modulus of elasticity? Because in the result, you showed that the modulus of elasticity was not significantly different when you increased the distance.

2. You used the average value at different times (20, 40, 60 sec) as a representation for each distance. In your opinion, is this a good representation? (If you look at each exposure time and compare between each distance group, it showed some trend, both increase and decrease, that might worth the further discussion.)

In the result of your presentation, you showed that the distance did not affect the modulus of elasticity. Please explain why do you conclude that the tip of the light curing unit should be placed closet to the surface of the restoration.

Dear Dr. Kornpavee simapronchai,

Thank you for your question

The results of distance showed that the modulus of elasticity of resin cement was not statistical significant different when increasing distance between light curing unit and specimens when using one-way ANOVA and post-hoc test so this is the reason why the distance is not effect to experimental results in this research.

Thank you

Thitinan (admin test)

test admin

Dear Dr. Ratcha Raksakmanut,

Thank you for your questions

1.Thank you for pointing this out. Our slide presentation of conclusion was mistake,we would explain that the longest time of curing and shortest distance of light curing unit will be greatest of modulus of elasticity of resin cement. From result in table 2 showed that at distance 0 mm and exposure time 60s showed the greastest modulus of elasticity.

2. In my opinion ,i think it may be not good representation which we used the average value at different times  as a representation for each distance because each group has different values that not trend to be the same way so we used average of modulus of elasticity for representation of each group to compare each other.

Thank you

Dear Dr. C Bumrungruan,

Thank you for your question

Thank you for pointing this out. Our slide presentation of conclusion was mistake,we would explain that the longest time of curing and shortest distance of light curing unit will be greatest of modulus of elasticity of resin cement. From result in table 2 showed that at distance 0mm and exposure time 60s showed the greastest modulus of elasticity.

Thank you

Dear Dr. Kornpavee simapronchai,

Thank you for your question

The results of distance showed that the modulus of elasticity of resin cement was not statistical significant different when increasing distance between light curing unit and specimens when using one-way ANOVA and post-hoc test so this is the reason why the distance is not effect to experimental results in this research.

Thank you

From the result in your study, what is your suggestion to apply in  clinical situations and explain the reason why? Thank you.

Dear Khun Thitnan, 

Thank you for a nice presentation. I would like to ask some questions/comments;

1. Why was not the thickness of the cement a parameter in your study? This relates to the energy release rate, or toughness, of the cement.

2. Why is Young's modulus of the cement an important property? To me, so called cohesive parameters would be the natural choice to evaluate. Young's modulus is a material parameter and will not change (unless you would estimate it at the nano scale). Please contact me through the Faculty of Biomedical Engineering if you would like more information about cohesive parameter evaluation. 

3. What are you actually measuring using your 3-point bending experiment? Are you loading a beam of bulk cement? If so, it will not give you the properties for adhesion of the cement. Again, you will need to evaluate the cohesive parameters in order to get the material properties of the cement.   

4. There are two variables that you change, i.e. distance and time, thus, it is a two parameter optimization problem and it would result in 4 experiments (4-factorial) to draw conclusions. However, it would make sense to perform a central composite DoE instead since the expectation is that your output will not vary linearly.    

I apologize for all the questions and comments. However, see it like this, a lot of questions means that it is an interesting topic.

Best regards,

Kent 

Dear Dr. Phanassaya,

Thank you for your question

In clinical situations, I suggest that the longest time of curing and shortest distance of light curing unit will be greatest of modulus of elasticity of resin cement because from result in table 2 showed that at distance 0 mm and exposure time 60s showed the greastest modulus of elasticity which modulus of elasticity are important properties that reflect the ability of the cement to manage stress without resulting into fracture of restotration.

Thank you

Dear PROF. KENT SALOMONSSON

Thank you for your questions and kind attention of our study.

1. The thickness of the resin cement was not calculated in this study, although the thickness of the resin cement would affect to various factors in the experiment. But according to many reseach studies and ISO requirements showed that the resin cement should have the thickness of 2 mm . Therefore our group has determined the thickness of the resin cement at 2 mm and not used the thickness of the resin cement as a parameter in this study.

2. Modulus of elasticity are useful basic parameters for the assessment of mechanical characteristics of dental materials. The modulus of elasticity of cements are the one of the main factors that affect fracture resistance of the restoration and failure resistance of cemented restorations under applied forces is related to the mechanical properties of the restoration.Therefore ,modulus of elasticity are important properties that reflect the ability of the resin cement to manage stress without resulting into fracture of restoration.

3. In the experimental we used 3-point bending testing to find the value modulus of elasticity of resin cement. We press by using maximum load 50 newtons at the center of the specimens until the specimens break.Our experiment design similar to the previous study of A.U.J.Yap (A.U.J.Yap et al.,2003).     

I really appreciate your valuable comments and suggestion,which helped us to improve the quality of work. And I would like to thank you for giving me the opportunity to find the deep information to develop our research in the future.

Best regards,

Thitinan