Profilometer Comparison of the Surface Roughness of Four Denture Base Resins: An In Vitro Study

Round 1

Reviewer 1 Report

1.The content of the abstract is too sloppy, and there is no need to explain

   the meaning of each R value in the abstract section.

2.If the author obtains the value of Ra directly after the polymerization

   process of the polymer material is completed (Fig 2), why does it need to

   be polished to measure the surface roughness instead of directly

   measuring Ra (in abstract)?

3. In the sample preparation in section 2.1, please provide references

   explaining the effect of diamond grinding time on resin surface roughness.

4. What is SSG? SSE? The value of F test is no longer in the 95% critical

   acceptance range, and subsequent statistics and analysis have no meaning

   for discussion.

5. It is recommended to refer to the relevant literature from the content of

    line 142-284 and rewrite it. The current writing is not the way of

   presentation in academic journals.

6.Most of the discussion content in Section 4 can be merged with Section 1.

   The current discussion does not contribute much to dental academics.

Author Response

# Reviewer 1

1.The content of the abstract is too sloppy, and there is no need to explain the meaning of each R value in the abstract section.

- Thank you so much for your observations.  The abstract has been corrected, as follows: The surface irregularities of the denture base resin roughness profile is one of the components characterizing the superficial topography of dental prosthesis, and it is a critical parameter for describing surface morphology. Generally, the increment of the surface roughness minimizes cleanability and promotes the rate of bacterial adherence, affecting the expression of bacterial adhesins. The purpose of this in vitro study was to investigate the roughness of four commercially available denture-based resin employed for removable prosthodontics. Methods: twenty-five specimens were realized and submitted to observation for three dimensions (perpendicular, parallel, 45 degree). Average surface roughness (Ra), Rz, Rq, Rv, and Rpwere measured with a calibrated mechanical roughness tester (Taylor Hobson Surtronic 25; Taylor Hobson, Leicester, UK). Data were analysed with one-way ANOVA analysis of variance and post hoc Tukey’s test; p ≤ 0.05 was considered a statistically significant difference. Results: Significant differences in Ra between the groups were assessed. Baltic Denture System™ (Merz Dental GmbH) showed a lower surface roughness coefficient and the more homogeneous surface. Conclusions: Functional importance of surface roughness parameters denture base materials must be explored, not only considering recognised surface features.

2.If the author obtains the value of Ra directly after the polymerization process of the polymer material is completed (Fig 2), why does it need to be polished to measure the surface roughness instead of directly measuring Ra (in abstract)?

- Thank you so much for your observation. This was a coarse error of transcription. The abstract has been modified, and the errors of transcriptions deleted.

3. In the sample preparation in section 2.1, please provide references explaining the effect of diamond grinding time on resin surface roughness.

-Thank you for your observations. We have performed an analysis of literature about the effect of diamond grinding time, but we have only revealed references about the type of polishing cloths which determine the effect on resin surface roughness.

4. What is SSG? SSE? The value of F test is no longer in the 95% critical acceptance range, and subsequent statistics and analysis have no meaning for discussion.

- Thank you so much for your considerations. The SSG and SSE have been explained and added in the text, as follows: Sum of square between groups (SSG) + the squared differences of each observation average from the overall average (SSE).

5. It is recommended to refer to the relevant literature from the content of line 142-284 and rewrite it. The current writing is not the way of presentation in academic journals.

- Thank you so much for your considerations. The writing has been modified.

6.Most of the discussion content in Section 4 can be merged with Section 1. The current discussion does not contribute much to dental academics.

- Thank you for your consideration. We have added part of discussion into the Introduction section and a more detailed discussion has replaced the old version.

Reviewer 2 Report

This research measured the surface roughness of 4 different denture base resins. The experiment is simple, and the clinical significance is limited. There are some issues to be considered:

1. In the abstract section, it was said two-way ANOVA was used, but there were only one-way ANOVAs used in the method and result section.
2. The introduction and discussion are too short.
3. The experiment was poorly carried out, where wax patterns and denture base resins were not of the same size as shown in Fig. 1 and Fig. 2.
4. The experimental methods of this study were not adequately introduced. The polishing procedures, which will affect the surface roughness, were not detailed.
5. Authors said: Roughness was measured in three dimensions of each sample: perpendicular, parallel, and at 45°.
   reviewer’s comments: please define these three dimensions and explain with figures, and describe the clinical significances.
6. Although several tables of the results were sorted out, please note that some tables are not necessary.
7. The histograms in Figure 4 and Figure 5 are not easy to read because lack of legend.
8. The results in the Table 7 should be described with mean and SD.
9. Please explain the clinical significance of Ra, Rz, Rq, etc.

Author Response

# Reviewer 2

This research measured the surface roughness of 4 different denture base resins. The experiment is simple, and the clinical significance is limited. There are some issues to be considered:

1. In the abstract section, it was said two-way ANOVA was used, but there were only one-way ANOVAs used in the method and result section.

- Thank you for your corrections. This was an error. It has been corrected with "one-way ANOVA", as discussed.

2. The introduction and discussion are too short

- Thank you for your consideration. We have added part of discussion into the Introduction section and a more detailed discussion has replaced the old version.

3. The experiment was poorly carried out, where wax patterns and denture base resins were not of the same size as shown in Fig. 1 and Fig. 2.

- We apologize. Effectively the images were the raw ones. We have included the final images of the samples used for the purpose of the experiment, as follows:

Fig 1. The slot of plasters (a, b).

• The slots                                            (b) The wax patterns into the slots

Fig. 2. Samples of each resin material (a, b, c, d).

• Polyamide

• Baltic

• ProBaseHot

• ProbaseCold

4. The experimental methods of this study were not adequately introduced. The polishing procedures, which will affect the surface roughness, were not detailed.

Thank you for your considerations. The procedures have been added, as follows: “…Then, the finishing and polishing were executed by using a tungsten-carbide bur (HM 79GX-040 HP; Meisinger, Centennial, CO) with a thin cross cut at 18,000 rpm to remove any zone of main deformation consequent from initial cutting. Then, a coarse grain cylindrical rubber top bur for acrylic resin (Super Acrylic Polish; Lang Dental, Wheeling, IL) was employed, and then a fine grain cylindrical rubber top bur (Super Acrylic Polish) was used. Before polishing, samples were thoroughly cleaned and dried. The first polishing was accomplished using adhesive-backed emery paper, which are thought be less aggressive: surfaces were planed using a hard napless without excessive weight pressing down on the samples. Intermediate cleaning was carried out to minimize contamination of abrasive materials. Cleaning was required to remove polishing residues. This requirement for cleanliness was also applied to the operator's hands. Final polishing was performed by using 6 or 3µm diamond embedded on a napped cloth. Blocks with a 3 mm-thick layer were produced, providing 100 samples measuring 10x12x3 mm. Then, the specimens were stored in distilled water at 37°C for 48 ± 2 hours prior testing.

5. Authors said: Roughness was measured in three dimensions of each sample: perpendicular, parallel, and at 45°. reviewer’s comments: please define these three dimensions and explain with figures, and describe the clinical significances.

- Thank you so much for your considerations. We think that it is an intrinsic concept that not requires an explanation. Unfortunately, we don’t have figures to explain the dimensions.

6. Although several tables of the results were sorted out, please note that some tables are not necessary.

- Each table represents the results discussed. Please, point us to any tables that you do not feel are necessary.

7. The histograms in Figure 4 and Figure 5 are not easy to read because lack of legend.

-Thank you so much for your observation. The legend has been added, as follows: Histogram of residuals. The histogram of the residuals showing the distribution of the residuals for all observations.

8. The results in the Table 7 should be described with mean and SD.

Thank you so much for your observation. The descriptive analysis has been added, as follows:

9. Please explain the clinical significance of Ra, Rz, Rq, etc.

- Thank you so much for your observation. The clinical significance has been explained and added, as follows: “…analysing the surface roughness parameters, and then the statistical differences between the root mean square average of the profile heights over the evaluation length (Rq), the distance between the deepest valley of the profile and the mean line within the evaluation length (Rv), and the distance between the highest point of the profile and the mean line within the evaluation length (Rp).

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear authors,

I reviewed this paper with interest.

There are several issues that should be addressed in the manuscript before further consideration for publication.

Line 77 and others.

You should add “materila, companies, head offices, city or state and Country”in manuscript.

Line 119-131.

What kind of polishing material did you use?

You should add “materila, companies, head offices, city or state and Country”in manuscript.

Because surface roughness of specimen is influenced by polishing materials.

Line 138.

Distribution of data indicaed normal distribution.

Data was analyzed ANOVA and Tukey HSD test. Variance of data should be analyzed by Homogeneity test such as Levene test before using ANOVA.

If variances of data are not equal, Dunnet’s T3 test or t-test (Welch method) with Bonferroni correction can be used to analyze data with non-homogeneous variances for post hoc test and “ANOVA” can’t be used.

You should add  “soft-ware, ver., companies, head offices, city or state and Country in M and M.

In results.

“ P” value need to replace with “p” value.

Line 166, 202 and 241.

Effect size is mentioned “Large”

Please add some references about strength of effect size such as small, moderate and large  

Histogram of Figure 3,5 and 7.

Outlier data of surface roughness is observed in Histogram on attached file.

You should mention about this cause in discussion part.

Line 288.

“Surface” is  Italic.

Is there any reason?

Comments for author File: Comments.docx

Author Response

#Reviever 3

Dear authors,

I reviewed this paper with interest. There are several issues that should be addressed in the manuscript before further consideration for publication.

Line 77 and others.

You should add “materila, companies, head offices, city or state and Country”in manuscript.

• Thank you for your observation. The company and countries were indicated, as follows: 1) Microcrystalline polyamide denture base material (QUATTROTI SRL, DENTAL D-N). Polyamide is a thermoplastic material that is widely used as a denture base material because of higher elasticity, toxicological safety and a chemical-resistant material; 2) Baltic Denture System™ (Merz Dental GmbH), used for fabrication of CAD/CAM complete denture; 3) Acrylic resin (ProBaseCold; IvoclarVivadent, Schaan, Liechtenstein); 4) Acrylic resin (ProBaseHot; IvoclarVivadent, Schaan, Liechtenstein)

Line 119-131. What kind of polishing material did you use? You should add “materila, companies, head offices, city or state and Country”in manuscript. Because surface roughness of specimen is influenced by polishing materials.

• Thank you so much for your observation. The requested informations have been added, as follows: Then, the finishing and polishing were executed by using a tungsten-carbide bur (HM 79GX-040 HP; Meisinger, Centennial, CO) with a thin cross cut at 18,000 rpm to remove any zone of main deformation consequent from initial cutting. Then, a coarse grain cylindrical rubber top bur for acrylic resin (Super Acrylic Polish; Lang Dental, Wheeling, IL) was employed, and then a fine grain cylindrical rubber top bur (Super Acrylic Polish) was used.

Thank you for your observation.

Line 138. Distribution of data indicaed normal distribution. Data was analyzed ANOVA and Tukey HSD test. Variance of data should be analyzed by Homogeneity test such as Levene test before using ANOVA. If variances of data are not equal, Dunnet’s T3 test or t-test (Welch method) with Bonferroni correction can be used to analyze data with non-homogeneous variances for post hoc test and “ANOVA” can’t be used. You should add “soft-ware, ver., companies, head offices, city or state and Country in M and M.

- Thank you so much for your correction. Really, we conducted the Levene test because of non-normally distributed data. The transcription was a coarse error. We have corrected, as follows: Data analysis was conducted employing IBM SPSS 20.0 Statistics for mac (IBM Inc., New York, USA). In the descriptive analysis, the mean and standard deviation was calculated for each group. Non-normally distributed data were found and the Levene's test to assess the equality of variances was performed

Then, statistical analysis was performed through one-way ANOVA test. Differences were analysed using parametric Tukey’s multiple

comparisons to determine which materials differed from the others with significance limit established to 5% (p ≤ 0.05) level.

In results.

“P” value need to replace with “p” value.

• Thank you so much for your correction. The correction has been applied.

Line 166, 202 and 241. Effect size is mentioned “Large”. Please add some references about strength of effect size such as small, moderate and large

• Thank you for your observation. Effect size tells how meaningful the relationship between variables or the difference between groups is. A large effect size means that a research finding has practical significance, while a small effect size indicates limited practical applications. While statistical significance shows that an effect exists in a study, practical significance shows that the effect is large enough to be meaningful in the real world. Statistical significance is denoted by p-values, whereas practical significance is represented by effect sizes.

Histogram of Figure 3,5 and 7. Outlier data of surface roughness is observed in Histogram as follows.

You should mention about this cause in discussion part.

• Thank you for your observation. We have added the histograms just for completeness of visuals results.

Line 288. “Surface” is Italic. Is there any reason?

-No. It was an error. It has been corrected.

Round 2

Reviewer 1 Report

No more comments.

Author Response

Reviewer 2 Report

Thank you very much for your revisions. I think the manuscript should be checked again for errors on statistics.

1. Rz was only appeared in Background of Abstract and Table 8. What is Rz? Please attention that, in Abstract, you introduced that as “Average surface roughness (Ra), Rz, Rq, Rv, and Rp were measured‘’, but in the last paragraph of Introduction and Materials and Methods, you not included this evaluation index(Rz). This may seem contradictory.
2. Please perform statistical analysis again. Non-normally distributed data should not be described with mean and SD, you can list the median and interquartile range of data. Additionally, it is inappropriate to use the statistical method of one-way ANOVA test in this study. Please apply nonparametric test.
3. In Table1-4, please retain the same number of decimal places in the same column.
4. Authors said: Roughness was measured in three dimensions of each sample: perpendicular, parallel, and at 45°. reviewer’s comments: Do you mean vertically, horizontally, and 45°?

Author Response

Thank you very much for your revisions. I think the manuscript should be checked again for errors on statistics.

1. Rz was only appeared in Background of Abstract and Table 8. What is Rz? Please attention that, in Abstract, you introduced that as “Average surface roughness (Ra), Rz, Rq, Rv, and Rp were measured‘’, but in the last paragraph of Introduction and Materials and Methods, you not included this evaluation index(Rz). This may seem contradictory.

• Thank you so much for your consideration. This was an error. The measurement was removed in draft. The Rz has been deleted.

1. Please perform statistical analysis again. Non-normally distributed data should not be described with mean and SD, you can list the median and interquartile range of data. Additionally, it is inappropriate to use the statistical method of one-way ANOVA test in this study. Please apply nonparametric test.

• Thank you so much for your consideration. The Kruskal-Wallis test, a nonparametric test and is used when the assumptions of ANOVA are not met, was applied as follows:

Results

Descriptive Statistics

Summary statistics were calculated for Ra, Rv, Rp, and Rq.

Summary Statistics

The observations for Ra had an average of 7.12 (SD = 1.19, SE_M = 0.23, Min = 4.60, Max = 9.32, Skewness = -0.06, Kurtosis = -0.72). The observations for Rv had an average of 10.07 (SD = 2.47, SE_M = 0.47, Min = 7.89, Max = 15.55, Skewness = 1.28, Kurtosis = 0.09). The observations for Rp had an average of 10.88 (SD = 1.72, SE_M = 0.33, Min = 5.67, Max = 13.11, Skewness = -1.03, Kurtosis = 1.24). The observations for Rq had an average of 34.26 (SD = 5.00, SE_M = 0.95, Min = 21.56, Max = 43.12, Skewness = -0.29, Kurtosis = -0.20). The summary statistics can be found in Table 1.

Table 1

Summary Statistics Table for Interval and Ratio Variables

Sample Minimum (Min): The smallest numeric value in a given sample; Sample Maximum (Max): The largest numeric value in a given sample; Skewness: The measure of asymmetry in the distribution of a variable. Positive skewness indicates a long right tail, while negative skewness indicates a long left tail; Kurtosis: The measure of the tail behavior of a distribution. Positive kurtosis signifies a distribution is more prone to outliers, and negative kurtosis implies a distribution is less prone to outliers; Mean (M): The average value of a scale variable.Percentage (%): The percentage of the frequency or count of a nominal or ordinal category; Standard Deviation (SD): The spread of the data around the mean of a scale variable; Standard Error of the Mean (SE_M): The estimate of how far the sample mean is likely to differ from the actual population mean.

Kruskal-Wallis Test

A Kruskal-Wallis rank sum test was conducted to assess if there were significant differences in Ra, Rv, Rp, Rq between the levels of Group.

Results

Ra: The results of the Kruskal-Wallis test were significant based on an alpha value of .05, χ²(3) = 8.23, p = .041, indicating that the mean rank of Ra was significantly different between the levels of Group. Table 2 presents the results of the Kruskal-Wallis rank sum test. Figure 1 presents boxplots of the ranked values of Ra by the levels of Group.

Table 2

Kruskal-Wallis Rank Sum Test for Ra by Group

Figure 1

Ranked Values of Ra by the levels of Group

Post-hoc. Pairwise comparisons were examined between each level of Group. The results of the multiple comparisons indicated significant differences based on an alpha value of .05 between Myc-Baltic. Table 3 presents the results of the pairwise comparisons.

Table 3

Pairwise Comparisons for the Mean Ranks of Ra by Levels of Group

Rv: The results of the Kruskal-Wallis test were significant based on an alpha value of .05, χ²(3) = 17.47, p < .001, indicating that the mean rank of Rv was significantly different between the levels of Group. Table 4 presents the results of the Kruskal-Wallis rank sum test. Figure 2 presents boxplots of the ranked values of Rv by the levels of Group.

Table 4

Kruskal-Wallis Rank Sum Test for Rv by Group

Figure 2

Ranked Values of Rv by the levels of Group

Post-hoc. Pairwise comparisons were examined between each level of Group. The results of the multiple comparisons indicated significant differences based on an alpha value of .05 between the following variable pairs: Baltic-Pro Base Hot and Pro Base Hot-Pro Base Cold. Table 5 presents the results of the pairwise comparisons.

Table 5

Pairwise Comparisons for the Mean Ranks of Rv by Levels of Group

Rp: The results of the Kruskal-Wallis test were significant based on an alpha value of .05, χ²(3) = 16.19, p = .001, indicating that the mean rank of Rp was significantly different between the levels of Group. Table 6 presents the results of the Kruskal-Wallis rank sum test. Figure 3 presents boxplots of the ranked values of Rp by the levels of Group.

Table 6

Kruskal-Wallis Rank Sum Test for Rp by Group

Figure 3

Ranked Values of Rp by the levels of Group

Post-hoc. Pairwise comparisons were examined between each level of Group. The results of the multiple comparisons indicated significant differences based on an alpha value of .05 between the following variable pairs: Myc-Baltic and Myc-Pro Base Cold. Table 7 presents the results of the pairwise comparisons.

Table 7

Pairwise Comparisons for the Mean Ranks of Rp by Levels of Group

Rq: The results of the Kruskal-Wallis test were significant based on an alpha value of .05, χ²(3) = 15.64, p = .001, indicating that the mean rank of Rq was significantly different between the levels of Group. Table 8 presents the results of the Kruskal-Wallis rank sum test. Figure 4 presents boxplots of the ranked values of Rq by the levels of Group.

Table 8

Kruskal-Wallis Rank Sum Test for Rq by Group

Figure 4

Ranked Values of Rq by the levels of Group

•  
• Post-hoc. Pairwise comparisons were examined between each level of Group. The results of the multiple comparisons indicated significant differences based on an alpha value of .05 between the following variable pairs: Myc-Baltic and Myc-Pro Base Hot. Table 9 presents the results of the pairwise comparisons.

Table 9

Pairwise Comparisons for the Mean Ranks of Rq by Levels of Group

1. In Table1-4, please retain the same number of decimal places in the same column.

-Thank you so much for your consideration. The tables have been removed.

1. Authors said: Roughness was measured in three dimensions of each sample: perpendicular, parallel, and at 45°. reviewer’s comments: Do you mean vertically, horizontally, and 45°?

-Yes. It has been corrected.

Round 3

Reviewer 2 Report

Authors modified the manuscript according to the review comments, suggest to accept after minor revision:

In materials and methods section: “Roughness was measured in three dimensions of each sample: perpendicular, parallel, and at 45°” -> “Roughness was measured in three dimensions of each sample: vertically, horizontally, and at 45°”

Author Response

Thank you for your correction. This was an error. The modification has been highlighted in red.