Name: roughness impact of piezoelectric dental scaler on two distinct flowable composite filling materials
Uploaded: 2025-01-10T13:30:00.000+00:00
Duration: 5 min 30 s
Description: Dental ultrasonic scalers are commonly employed in periodontal treatment; however, their ability to roughen tooth surfaces is a worry since roughness may ...

I express my gratitude to Prof. Dr. O&#287;uzhan G&#252;nd&#252;z from Marmara University Nanotechnology and Biomaterials Application and Research Center/Marmara University Faculty of Technology Department of Metallurgy and Material Engineering; Prof. Dr. P&#305;nar Y&#305;lmaz Atal&#305; from Marmara University Faculty of Dentistry, Department of Restorative Dentistry; and Dr. Semra &#220;nal Yildirim from Marmara University Genetic and Metabolic Diseases Research and Investigation Center who provided valuable insights and expertise that seriously supported the investigation.

NOTE: This research employed two distinct kinds of flowable dental composite materials: nanohybrid Group P, and nanohybrid Group B manufactured using unique giomer technology. Casarin et al.&#39;s study17 parameters (mean defect depth difference (Ra; &#181;m): 15, standard deviation (&#181;m): 10, alpha error: 0.05, beta error: 0.90) were utilized in a power analysis to estimate sample size.
1. Creation of composite specimens with similar initial surface roughness
<ol>
	<li>Obtain a piece of transparent glass, a rubber gasket, and a piece of transparent tape to make a composite sample with a thickness of 2 mm and a diameter of 7 mm in accordance with ISO specifications18 (Figure 1A).</li>
	<li>After placing the gasket on the transparent tape, apply the composite sample to the gasket, condense it, and close the transparent glass over the gasket and the composite sample (Figure 1B, C).</li>
	<li>Polymerize the composite material using a light curing system for 20 s from the top and 20 s from the bottom (Figure 1D, E). Use the same system for the other sample as well.</li>
	<li>Use a polishing system for the same length of time and, in the same way, to achieve similar levels of roughness on the surfaces of the composite samples to be analyzed (Figure 2A, B). Immerse in distilled water for 24 h after polishing.</li>
	<li>Prepare an additional composite sample from both composite groups and record the initial electron microscope images at different magnifications (1000x, 2000x, 5000x magnification (Figure 3A,B). Coat the samples with gold for 90 s at 18 mA using a sputter coater and examine the samples using scanning electron microscopy (SEM) at an accelerating voltage of 10 kV.</li>
</ol>
2. Stabilization of the samples into acrylic blocks
<ol>
	<li>Find a plastic l-connection hanger element that is used to fix the kitchen terraces to the wall (Figure 4A). The product consists of two parts. The outer part is made of plastic, and the inner part consists of a metal cover. Just use the plastic part.</li>
	<li>Fill the bottom and back of the plastic part with cold-curing pink acrylic and allow the acrylic to polymerize and harden on a flat surface. Subsequently, excise a section of the holder using a diamond cutting disk, and use a monster lab bur to create a groove that will accommodate the fixation of any specimen (Figure 4B).</li>
	<li>Use the silicone impression material to make a copy of the plastic and acrylic mixture holder prototype. Then, make a negative version of the prototype. This will allow to make enough holders to hold all the specimens separately (Figure 4C).</li>
	<li>Use cold-curing acrylic to fill in the negative and then create sufficient holders. Next, use cold-curing acrylic to stabilize the composite specimens and mark the region where the instrument will be applied (Figure 4D).</li>
	<li>Collect the profilometric measurements. Go to the measure condition tab in the menu of the profilometer. Click on the Settings tab and make the relevant numerical settings as follows: &#955;c = 0.8, &#955;s = 2.5, and Opt length = 2. These settings perform the read-out of the surface roughness at over 2 mm with a cut-off value of 0.8 mm at a speed of 0.25 mm/s (Figure 5A).</li>
	<li>Mark 2 mm below the top center of the composite specimen with the help of a caliper (Figure 5B). Adjust the sensitive tip of the profilometer to that point. Then, start the profilometric measurement. Measure each sample&#39;s average roughness (Ra) using a contact profilometer.</li>
	<li>Verify the readings using the designated locations of each specimen (middle top). For each reading, move the device&#39;s needle 2 mm inside the indicated region (Figure 5C, D). Measure the surface properties of each specimen 3x and compute the average before and immediately after the instrumentation operations.</li>
</ol>
3. Creating the setup for the scaler application
<ol>
	<li>Obtain a parallelometer (Figure 6A). Fix the acrylic block on the table of the parallelometer (Figure 6B, C).</li>
	<li>Obtain a rubber pipe clamp with a triphone, which is used for fixing pipes by mounting them to a wall, ceiling, or floor. Use this to attach the handpiece of the device to the holder arm of the parallelometer (Figure 7A). Increase the number of clamp parts and the amount of rubber in accordance with the thickness of the handpiece. Thicken the screw part of the clamp with cold-curing acrylic (Figure 7B) so that it can be inserted into the holding arm of the parallelometer (Figure 7C).</li>
	<li>Apply the ultrasonic scaler, which is designed for supragingival deposit removal, to each composite material for 60 s using this unique setup at an angle of 0&#176;, at maximum power, under water cooling, and with equal force on a specified designated region (Figure 8A, B, C, D).</li>
	<li>Following the scaler application, repeat the profilometric measurements and the scanning electron microscope imaging for each sample (Figure 9A,B).</li>
</ol>

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The author declares no conflict of interest.

Research consistently shows that both sonic and ultrasonic scaling can increase the surface roughness of tooth-colored restorative materials, with ultrasonic scaling having a more detrimental effect8,9. Ultrasonic scaling and air-powder polishing can further increase the roughness of composite resin and restoration margins, and the extent of damage is material-dependent6. The type of restorative material used can also impact the extent of surface damage, with flowable and silorane-based composites showing smoother surfaces and lower bacterial count1. The current study&#39;s findings contribute to the existing body of literature on the effects of ultrasonic scaling on the surface roughness of composite fillings.
A comparative analysis of the two groups in this study, nanohybrid Group P (monomer content: Bis-EMA, TEGDMA; filler content: pre-polymerized filler, barium glass, silica filler) and patented giomer nanohybrid Group B (monomer content: Bis-GMA, TEGDMA; filler content: glass filler, fluoroboroaluminosilicate glass), revealed no significant difference in roughness alteration following scaler application. This finding is noteworthy as it indicates that advancements in composite technology, specifically giomer-based formulations, do not inherently convey resistance to scaler-induced roughness alterations. The lack of statistically significant difference in the degree of roughness added to both composite types might be discussed considering the material&#39;s filler content and particle size. While the technology and monomer content vary, the mechanical impact of scaling could be independent of these factors, affecting only the most superficial layer where similarities between the composites may be more pronounced. The results obtained here suggest that while technologically advanced composite materials may offer several clinical benefits, their resistance to mechanical alterations induced by scaling must be critically evaluated. Dental practitioners should consider the implications of these findings when performing scaling on patients with composite restorations and possibly favor the use of less abrasive instruments or techniques to maintain surface integrity.
In order to conduct a comparison by examining the surface change of any material, it is necessary that the initial surface characteristics of the materials being compared are comparable. The minimum amount of energy required for the polymerization of the composite materials used in the present study was reported as 10 J/cm2 by the manufacturers19. According to the manufacturer&#39;s instructions, the light curing system used in the present investigation delivers between 1 J and 3 J of energy per cm2 per second. Checci et al.20 proved that extended curing duration enhances the mechanical characteristics of the composites. In accordance with the aforementioned facts, the light system was applied for the polymerization of the samples for a period of 20 s from the top and 20 s from the bottom. Flowable composites are distinguished by a reduced amount of filler material and a higher concentration of diluent monomers in the composition. Traditionally, these composites were made by maintaining the tiny particle size of conventional hybrid composites but lowering the amount of filler. This allowed for an increased amount of resin, which in turn decreased the viscosity of the mixture1,21. Nevertheless, the mechanical qualities of these composites, such as flexural strength and wear resistance, have been consistently shown to be worse when compared to traditional composites. Flowable composites have been proposed as suitable filler materials for low-stress applications and scenarios that involve challenging access or need effective penetration. In order to acquire similar initial surface roughness values in the present investigation, the tested flowable composite materials were polymerized and polished in the same manner, and similar surface roughness values were validated by analyzing the surface characteristics obtained by a profilometer. No manufacturer recommendation was available regarding the rpm value and polishing time for the polishing system employed in the present study22. The samples were polished to similar initial roughness values by the same individual using a 4-step polishing system, as illustrated in Figure 2.
The evidence regarding the effects of various ultrasonic devices commonly employed by experts is inconclusive23,24,25,26. According to Yousefimanesh et al.26, when the same forces were applied, piezoelectric scalers produced smoother root surfaces than magnetostrictive scalers. Flemmig et al.24 also reported that a magnetostrictive device was more aggressive on root surfaces than a piezoelectric device. Nevertheless, Busslinger et al.23 discovered that a piezoelectric device produced a coarser root surface than a magnetostrictive device following instrumentation. Singh et al.25 found that magnetostrictive and piezoelectric ultrasonic instruments created equivalent surface roughness levels and demonstrated comparable capabilities for creating a physiologically harmonious surface, which differed from the previous investigations. The inconsistent findings emphasize the need for greater study in this area. A recent study examined the effects of several ultrasonic scalers and polishing devices on the wear and roughness of root surfaces10. As a result, it is demonstrated that the application settings might have a significant impact on the roughness of the root surface. Furthermore, using the piezoelectric ultrasonic scaler at maximum intensity at a 0&#176; angle resulted in the biggest wear and roughness levels on the root surfaces. As a result, comparable application conditions were applied to the samples in the current investigation, where the most significant impact was found.
In surface analysis research, it is of great importance to be able to perform reproducible applications and establish standard exposures for all samples in order to avoid bias. Moreover, the capacity to precisely disclose the examined surface after the application is also extremely beneficial to the findings. Therefore, when conducting such studies, it is necessary to establish a setup to standardize individualized application and evaluation parameters. In terms of ultrasonic scaler application, the methodological factors that might affect the findings can be mentioned as follows: adjusted lateral force, tip angulation, power settings, and consistency of the application site to be examined10,24,26,27,28. The current study demonstrates that several critical methodological parameters can be acquired using a parallelometer, an acrylic block for securing the sample, and a custom holder that allows the handpiece to be applied to the sample at the desired angle with minimal contact force. In this methodological approach, the inability to measure and alter the force applied to the specimen represents a potential limitation of the constructed setup. On the other hand, it should be remembered that ultrasonic instruments should be applied to dental and restorative surfaces only in contact with the surface without any force in order to minimize any surface damage. Also, in the current setup, it is possible to clearly define the application zone, which is crucial for the exact analysis of the results revealed after the application.
The surface texture of dental composites is critical for their longevity and performance, as rougher surfaces may harbor more plaque and bacteria, leading to an increased risk for caries and periodontal disease. It has been shown that dental plaque accumulation is influenced by surface roughness, with a threshold of 0.2 &#181;m below which bacterial adherence is limited2. This is supported by in vivo studies that have found a correlation between surface roughness and plaque accumulation29,30. The present study demonstrates that the application of a piezoelectric ultrasonic scaler can indeed increase the roughness of composite material surfaces to a level that leads to plaque deposition. This effect was consistent across both tested material types.
It is also important to consider the limitations of this study. The in vitro nature of the experiment may not precisely replicate clinical conditions, particularly concerning the scaler&#39;s angle and the presence of saliva, which could modulate the effects seen. Long-term studies in a clinical setting would confirm these findings and provide a clearer understanding of the scaler&#39;s impact over time.
In conclusion, the present study underscores the importance of considering the physical effects of hygiene procedures on dental composites. Although the clinical significance of the observed roughness increase requires further investigation, the potential for increased plaque retention should inform clinical practices, emphasizing the need for careful scaling techniques around composite restorations.

Maintaining oral health is a cornerstone of comprehensive dental care, and the role of hygiene in the prevention and treatment of periodontal diseases is well-established. One tool employed during the hygiene phase is the dental ultrasonic scaler, which is used to remove dental calculus and plaque1. However, while the efficacy of the scaler in cleaning tooth surfaces is critical, its impact on restorative materials is a subject of ongoing research and interest within dental materials science. Surface roughness in particular has been shown to be a contributor to the accumulation and retention of plaque2, highlighting the need for an understanding of how commonly used dental instruments affect restorative materials.
Recent studies have conducted comparative analyses on the roughness effects of piezoelectric dental scalers on teeth or composite filling materials3,4,5. Mittal et al.5 found that root surfaces scaled with a piezoelectric scaler were less rough than those scaled with a magnetostrictive scaler, although the former lost more material and had more noticeable scratches. Arabac&#305; et al.3 examined the influence of tip wear on root surface roughness using piezoelectric ultrasonic scalers and found differences in erosion ratio based on tip wear. Goldstein et al.4 reported that a magnetostrictive ultrasonic scaler had more adverse effects on the surface roughness of resin-based restorative materials compared to a sonic scaler. Recent research has shown that the use of ultrasonic scaling and air polishing can significantly increase the surface roughness of composite filling materials6,7. These findings are important as increased surface roughness can lead to bacterial adhesion and compromise the longevity of dental restorations. Therefore, it is crucial for dental professionals to consider the potential impact of these procedures on the surface roughness of composite filling materials.
This study seeks to expand the body of knowledge by investigating the roughness effect induced by piezoelectric ultrasonic dental scalers on restorative materials, specifically two different flowable composite filling materials. Given the prevalence of composite materials in restorative dentistry and their differentiation in terms of monomer content and technology, such as conventional composites versus giomer-based composites, it is imperative to assess whether the use of ultrasonic scalers differently affects these materials6,8,9,10. Flowable composites are defined by a reduced filler content, which ultimately results in diminished mechanical properties. Consequently, these materials are unsuitable for use in high-stress-bearing locations such as cervical tooth regions11. In recent decades, manufacturers have launched a new generation of flowable materials with increased mechanical and physical qualities. These materials are stated to be appropriate for use in a wide variety of direct anterior and posterior restorations, including those exposed to extreme stress. Consequently, it is of clinical value to examine the mechanical and physical qualities of several commercially available high-strength flowable dental composites12. By meticulously comparing the roughness effect of scalers on two distinct flowable composite filling materials, the study aims to inform clinical practice, ensuring that procedures optimize both oral health outcomes and the longevity and aesthetics of these recent restorative materials. In assessing the impact of dental instruments on various surfaces, standardization of application across all groups is crucial for ensuring the accuracy of the data obtained. Standardizing characteristics such as tip type, angulation, wear, applied force, movement in dental scaler applications, and similar initial surface characteristics would enhance the quality of these investigations3,13,14,15,16. The configurations established for similar investigations mostly include elements that feature a scale to quantify the applied force, an item to provide the requisite weight for the handpiece, and a limb or individual to carry and apply the hygiene equipment. Standardizing the setup for ultrasonic dental scalers enhances consistency, minimizes variability due to different individual parameters, and improves diagnostic accuracy for assessing surface alterations. The setup configuration revealed similar initial surface properties established in this study to reduce discrepancies in individual-specific applications and provide better outcomes. Additionally, it is distinctive regarding the various items utilized. Furthermore, the method is straightforward and can be readily adopted by a wide range of medical practitioners.
This investigation, through a standardized and controlled in vitro approach, strives to delineate the effects of ultrasonic dental scaler application that result in significant roughness, which is crucial for refining dental hygiene protocols and enhancing the sustainable health of restored teeth.

<table><tbody><tr><td>Beautifil Flow Plus</td><td>Shofu</td><td></td><td>United States</td></tr><tr><td>Evo MA10 Scanning Electron Microscope</td><td>Zeiss</td><td></td><td>Germany</td></tr><tr><td>EWO Typ 990 Paralellometer</td><td>Kavo</td><td></td><td>Germany</td></tr><tr><td>Finishing Discs</td><td>Bisco</td><td></td><td>United States</td></tr><tr><td>G4 Scaler Tip</td><td>Woodpecker</td><td></td><td>China</td></tr><tr><td>Premise Flowable</td><td>Kerr</td><td></td><td>United States</td></tr><tr><td>SC 7620 model sputter coater</td><td>Quorum Technologies</td><td></td><td>UK</td></tr><tr><td>Surftest SJ-210</td><td>Mitutoyo</td><td></td><td>Japan</td></tr><tr><td>UDS-A-LED Dental Scaler</td><td>Woodpecker</td><td></td><td>China</td></tr><tr><td>Valo LED Cordless Curing Light</td><td>Ultradent</td><td></td><td>United States</td></tr><tr><td>Zetaplus Silicon Impression Material</td><td>Zhermack</td><td></td><td>Italy</td></tr></tbody></table>

roughness impact of piezoelectric dental scaler on two distinct flowable composite filling materials

Dental ultrasonic scalers are commonly employed in periodontal treatment; however, their ability to roughen tooth surfaces is a worry since roughness may increase plaque production, a key cause of periodontal disease. This research studied the influence of a piezoelectric ultrasonic scaler on the roughness of two distinct flowable composite filling materials. To do this, 10 disc-shaped samples were generated from each of the two flowable composite materials. After standardized polishing, samples were submerged in water for 24 h before the first surface examination using electron microscopy and profilometry. The ultrasonic scaler was applied to a specified location of each sample for 60 s under water cooling and regulated force. Post-scaler surface parameters were again examined. Following the application of the scaler, both composite materials exhibited a notable increase in surface roughness, as determined by profilometry (p &lt; 0.01). Additionally, the observed surface roughness was also qualitatively visualized with scanning electron microscopy. While initial roughness levels were comparable across the two composites (p = 0.143) after scaler application, no substantial discrepancy in surface texture was noticed between them (p = 0.684). The use of a high-power piezoelectric ultrasonic scaler on routinely used flowable composite restorations might generate considerable surface roughness, possibly leading to increased plaque accumulation. Nevertheless, it might be postulated that nanohybrid flowable composite materials having conventional monomer ingredients may demonstrate comparable surface alterations within the limitations of this experiment.

The statistical analyses were done using statistical analysis software. The Wilcoxon Signed Rank Test was performed to assess changes within the group. The Mann Whitney-U Test was employed to undertake intergroup comparisons. The significance level was determined at p &#60; 0.05.
In the intragroup profilometric comparison of both groups, it was noted that the scaler application resulted in a considerable roughness, which can be qualitatively visualized by electron microscope images (Group P, p = 0.005; Group B, p = 0.007; Table 1). In the intergroup profilometric comparison, analysis of the roughness changes after scaler application to both composite types whose beginning roughness levels were determined to be comparable (p = 0.143) showed no significant difference (p = 0.684; Table 2).
The efficacy of the innovative technique in standardizing the use of dental appliances is well shown by the typical outcomes. The notable rise in surface roughness seen in both flowable composite materials after ultrasonic scaler application underscores the potential effects of such devices on dental restorations. This finding highlights the need for meticulous evaluation of treatment parameters and material choice to reduce iatrogenic harm. The methodology developed in this study has the potential to be applied for further investigation of the effects of a variety of dental instruments on a variety of materials and under a variety of clinical conditions, thereby offering valuable insights to both dental practitioners and researchers.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/67446/67446fig01.jpg" /> 
Figure 1:&#160;Preparation and polymerization of composite disks. (A)&#160;The&#160;equipment required for composite disk preparation. (B)&#160;The application of the composite sample into the gasket. (C)&#160;The condensation of the composite sample between the transparent tape and the transparent glass. (D) The light curing device. (E) The polymerization of the composite sample. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/67446/67446fig02.jpg" /> 
Figure 2: Polishing application. (A) The disks used for polishing. (B) The polishing disk application on the composite sample. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/67446/67446fig03.jpg" /> 
Figure 3: SEM images before scaling application. The images are from (A) Group P, (B) Group B. From left to right, 1000x, 2000x, and 5000x magnification are shown. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/67446/67446fig04.jpg" /> 
Figure 4: Stabilization of the samples into acrylic blocks. (A)&#160;An example illustrating theplastic l-connection hanger element. (B) Cold-curing acrylic application into the plastic l-connection hanger element and preparation of the prototype of the specimen holder. (C) Using silicon-based impression material in order to create the negative of the holder prototype. (D) Insertion of the composite specimens on the acrylic holder. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/67446/67446fig05.jpg" /> 
Figure 5:&#160;Steps for profilometric measurement. (A)&#160;Profilometer settings, (B)&#160;profilometer tip adjustment, (C)&#160;profilometer tip contact with the specimen, (D) reading screen of the profilometer. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/67446/67446fig06.jpg" /> 
Figure 6:&#160;Fixation of the acrylic block with the composite specimen. (A) An illustration of the parallelometer used for the special setup. (B) The table of the parallelometer. (C) Exact positioning of the acrylic block. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig06large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/67446/67446fig07.jpg" /> 
Figure 7:&#160;Preparation for the stabilization of the handpiece of the scaler. (A) Holder arm of the parallelometer. (B) Modification of a rubber pipe clamp with triphone. (C) Fixation of the scaler handpiece to the holder arm. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig07large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/67446/67446fig08.jpg" /> 
Figure 8:&#160;Ultrasonic scaler application with equal force to a marked area with the help of a specially prepared apparatus. (A) Frontal view, (B) diagonal view, (C) lateral view of the application, (D) ultrasonic dental&#160;scaler. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig08large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/67446/67446fig09.jpg" /> 
Figure 9: SEM images after scaling application. The images are from (A) Group P and (B) Group B. From left to right, 1000x, 2000x, and 5000x magnification are shown. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67446/67446fig09large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>GROUPS</td>
			<td>Before &#181;m</td>
			<td>After &#181;m</td>
			<td>P value*</td>
		</tr>
		<tr>
			<td></td>
			<td>(Mean&#177; SD)</td>
			<td>(Mean &#177; SD)</td>
			<td></td>
		</tr>
		<tr>
			<td>Group P (n =10)</td>
			<td>0.16 &#177; 0.17</td>
			<td>0.44 &#177; 0.28</td>
			<td>0.005</td>
		</tr>
		<tr>
			<td>Group B (n =10)</td>
			<td>0.25 &#177; 0.26</td>
			<td>0.49 &#177; 0.26</td>
			<td>0.007</td>
		</tr>
		<tr>
			<td>P value#</td>
			<td>0.143</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>
Table 1: Intragroup roughness change. SD: Standard Deviation; * Wilcoxon Signed Rank Test, p &#706; 0.01, # Mann Whitney-U Test, p &#706; 0.05.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Groups</td>
			<td>Roughness change, &#181;m</td>
		</tr>
		<tr>
			<td></td>
			<td>(Mean &#177; SD)</td>
		</tr>
		<tr>
			<td>Group P (n = 10)</td>
			<td>0.27 &#177; 0.29</td>
		</tr>
		<tr>
			<td>Group B (n = 10)</td>
			<td>0.23 &#177; 0.18</td>
		</tr>
		<tr>
			<td>P value*</td>
			<td>0.684</td>
		</tr>
	</tbody>
</table>
Table 2: Evaluation of the roughness change between the groups. SD: Standard Deviation; * Mann Whitney-U Test, p &#706; 0.05.

This methodology allows applying a dental appliance on any specimen at any angle with standardized force and stability. This approach might be extensively used in health sciences to standardize the impacts of dental equipment with hand-holding elements such as micromotors, turbines, and ultrasonic scalers on varied surfaces.

Roughness Impact of Piezoelectric Dental Scaler on Two Distinct Flowable Composite Filling Materials

Dental ultrasonic scalers are commonly employed in periodontal treatment; however, their ability to roughen tooth surfaces is a worry since roughness may ...

roughness-impact-piezoelectric-dental-scaler-on-two-distinct-flowable

Nanyang Technological University

Research

JoVE Journal

Behavior

477 Views.  Marmara University. This methodology allows applying a dental appliance on any specimen at any angle with standardized force and stability. This approach might be extensively used in health sciences to standardize the impacts of dental equipment with hand-holding elements such as micromotors, turbines, and ultrasonic scalers on varied surfaces.

Video: Roughness Impact of Piezoelectric Dental Scaler on Two Distinct Flowable Composite Filling Materials

Two-photon Calcium Imaging in Mice Navigating a Virtual Reality Environment

In recent years, two-photon imaging has become an invaluable tool in neuroscience, as it allows for chronic measurement of the activity of genetically identified cells during behavior1-6. Here we describe methods to perform two-photon imaging in mouse cortex while the animal navigates a virtual reality environment. We focus on the aspects of the experimental procedures that are key to imaging in a behaving animal in a brightly lit virtual environment. The key problems that arise in this experimental setup that we here address are: minimizing brain motion related artifacts, minimizing light leak from the virtual reality projection system, and minimizing laser induced tissue damage. We also provide sample software to control the virtual reality environment and to do pupil tracking. With these procedures and resources it should be possible to convert a conventional two-photon microscope for use in behaving mice.

Here we describe the experimental procedures involved in two-photon imaging of mouse cortex during behavior in a virtual reality environment.

In recent years, two-photon imaging has become an invaluable tool in neuroscience, as it allows for chronic measurement of the activity of genetically ...

Determining Ultrasonic Vocalization Preferences in Mice using a Two-choice Playback Test

Mice emit ultrasonic vocalizations (USVs) during a variety of conditions, such as pup isolation and adult social interactions. These USVs differ with age, sex, condition, and genetic background of the emitting animal. Although many studies have characterized these differences, whether receiver mice can discriminate among objectively different USVs and show preferences for particular sound traits remains to be elucidated. To determine whether mice can discriminate between different characteristics of USVs, a playback experiment was developed recently, in which preference responses of mice to two different USVs could be evaluated in the form of a place preference.
First, USVs from mice were recorded. Then, the recorded USVs were edited, trimmed accordingly, and exported as stereophonic sound files. Next, the USV amplitudes generated by the two ultrasound emitters used in the experiment were adjusted to the same sound pressure level. Nanocrystalline silicon thermo-acoustic emitters were used to play the USVs back. Finally, to investigate the preference of subject mice to selected USVs, pairs of two differing USV signals were played back simultaneously in a two-choice test box. By repeatedly entering a defined zone near an ultrasound emitter and searching the wire mesh in front of the emitter, the mouse reveals its preference for one sound over another. This model allows comparing the attractiveness of the various features of mouse USVs, in various contexts.

Ultrasonic vocalizations (USVs) in mice differ depending on age, sex, condition, and genetic background. Using two ultrasound emitters broadcasting simultaneously in different locations, this two-choice test can evaluate murine recognition and preference responses to different characteristics of USVs.

Mice emit ultrasonic vocalizations (USVs) during a variety of conditions, such as pup isolation and adult social interactions. These USVs differ with age, ...

Holistic Facial Composite Creation and Subsequent Video Line-up Eyewitness Identification Paradigm

The paradigm detailed in this manuscript describes an applied experimental method based on real police investigations during which an eyewitness or victim to a crime may create from memory a holistic facial composite of the culprit with the assistance of a police operator. The aim is that the composite is recognized by someone who believes that they know the culprit. For this paradigm, participants view a culprit actor on video and following a delay, participant-witnesses construct a holistic system facial composite. Controls do not construct a composite. From a series of arrays of computer-generated, but realistic faces, the holistic system construction method primarily requires participant-witnesses to select the facial images most closely meeting their memory of the culprit. Variation between faces in successive arrays is reduced until ideally the final image possesses a close likeness to the culprit. Participant-witness directed tools can also alter facial features, configurations between features and holistic properties (e.g., age, distinctiveness, skin tone), all within a whole face context. The procedure is designed to closely match the holistic manner by which humans&#8217; process faces. On completion, based on their memory of the culprit, ratings of composite-culprit similarity are collected from the participant-witnesses. Similar ratings are collected from culprit-acquaintance assessors, as a marker of composite recognition likelihood. Following a further delay, all participants &#8212; including the controls&#160;&#8212; attempt to identify the culprit in either a culprit-present or culprit-absent video line-up, to replicate circumstances in which the police have located the correct culprit, or an innocent suspect. Data of control and participant-witness line-up outcomes are presented, demonstrating the positive influence of holistic composite construction on identification accuracy. Correlational analyses are conducted to measure the relationship between assessor and participant-witness composite-culprit similarity ratings, delay, identification accuracy, and confidence to examine which factors influence video line-up outcomes.

This applied experimental paradigm replicates circumstances by which an eyewitness to a real crime may create a holistic facial composite of the culprit from memory, and then attempt to identify the culprit from a video line-up containing the culprit or one in which he or she is not present.

The paradigm detailed in this manuscript describes an applied experimental method based on real police investigations during which an eyewitness or victim ...

Shrinkage of Dental Composite in Simulated Cavity Measured with Digital Image Correlation

Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage.
Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions.
The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the &#8220;tooth-restoration&#8221; interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material.

In order to understand the spatial development of polymerization shrinkage stress in dental resin-composite restorations, Digital Image Correlation was used to provide full-field displacement/strain measurement of restored model glass cavities by correlating images of the restoration taken before and after polymerization.

Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to ...

Medicine

Confocal Time Lapse Imaging as an Efficient Method for the Cytocompatibility Evaluation of Dental Composites

It is generally accepted that in vitro cell material interaction is a useful criterion in the evaluation of dental material biocompatibility. The objective of this study was to use 3D CLSM time lapse confocal imaging to assess the in vitro biocompatibility of dental composites. This method provides an accurate and sensitive indication of viable cell rate in contact with dental composite extracts. The ELS extra low shrinkage, a dental composite used for direct restoration, has been taken as example. In vitro assessment was performed on cultured primary human gingival fibroblast cells using Live/Dead staining. Images were obtained with the FV10i confocal biological inverted system and analyzed with the FV10-ASW 3.1 Software. Image analysis showed a very slight cytotoxicity in the presence of the tested composite after 5 hours of time lapse. A slight decrease of cell viability was shown in contact with the tested composite extracts compared to control cells. The findings highlighted the use of 3D CLSM time lapse imaging as a sensitive method to qualitatively and quantitatively evaluate the biocompatibility behavior of dental composites.

The most studied aspect of the biocompatibility of dental composites is their cytotoxicity 3D CLSM time lapse imaging combined with fluorescent signal quantification allows sensitive evaluation of the cell fate over time. Utilizing this method could be an efficient tool to assess the cytocompatibility of dental composites.

It is generally accepted that in vitro cell material interaction is a useful criterion in the evaluation of dental material biocompatibility. The ...

Oral Biofilm Formation on Different Materials for Dental Implants

Dental implants and their prosthetic components are prone to bacterial colonization and biofilm formation. The use of materials that provides low microbial adhesion may reduce the prevalence and progression of peri-implant diseases. In view of the oral environment complexity and oral biofilm heterogeneity, microscopy techniques are needed that can enable a biofilm analysis of the surfaces of teeth and dental materials. This article describes a series of protocols implemented for comparing oral biofilm formation on titanium and ceramic materials for prosthetic abutments, as well as the methods involved in oral biofilms analyses at the morphological and cellular levels. The in situ model to evaluate oral biofilm formation on titanium and zirconia materials for dental prosthesis abutments as described in this study provides a satisfactory preservation of the 48 h biofilm, thereby demonstrating methodological adequacy. Multiphoton microscopy allows the analysis of an area representative of the biofilm formed on the test materials. In addition, the use of fluorophores and the processing of the images using multiphoton microscopy allows the analysis of the bacterial viability in a very heterogeneous population of microorganisms. The preparation of biological specimens for electron microscopy promotes the structural preservation of biofilm, images with good resolution, and no artifacts.

Here, we present a protocol to evaluate oral biofilm formation on titanium and zirconia materials for dental prosthesis abutments, including the analysis of bacterial cells viability and morphological characteristics. An in situ model associated with powerful microscopy techniques is used for the oral biofilm analysis.

Dental implants and their prosthetic components are prone to bacterial colonization and biofilm formation. The use of materials that provides low ...

Plasma Polishing as a New Polishing Option to Reduce the Surface Roughness of Porous Titanium Alloy for 3D Printing

Porous titanium alloy implants with simulated trabecular bone fabricated by 3D printing technology have broad prospects. However, due to the fact that some powder adheres to the surface of the workpiece during the manufacturing process, the surface roughness in direct printing pieces is relatively high. At the same time, since the internal pores of the porous structure cannot be polished by conventional mechanical polishing, an alternative method needs to be found. As a surface technology, plasma polishing technology is especially suitable for parts with complex shapes that are difficult to polish mechanically. It can effectively remove particles and fine splash residues attached to the surface of 3D printed porous titanium alloy workpieces. Therefore, it can reduce surface roughness. Firstly, titanium alloy powder is used to print the porous structure of the simulated trabecular bone with a metal 3D printer. After printing, heat treatment, removal of the supporting structure, and ultrasonic cleaning is carried out. Then, plasma polishing is performed, consisting of adding a polishing electrolyte with the pH set to 5.7, preheating the machine to 101.6 &#176;C, fixing the workpiece on the polishing fixture, and setting the voltage (313 V), current (59 A), and polishing time (3 min). After polishing, the surface of the porous titanium alloy workpiece is analyzed by a confocal microscope, and the surface roughness is measured. Scanning electron microscopy is used to characterize the surface condition of porous titanium. The results show that the surface roughness of the whole porous titanium alloy workpiece changed from Ra (average roughness) = 126.9 &#181;m to Ra = 56.28 &#181;m, and the surface roughness of the trabecular structure changed from Ra = 42.61 &#181;m to Ra = 26.25 &#181;m. Meanwhile, semi-molten powders and ablative oxide layers are removed, and surface quality is improved.

Plasma polishing is a promising surface processing technology, especially suitable for 3D printing of porous titanium alloy workpieces. It can remove semi-molten powders and ablative oxide layers, thereby effectively reducing surface roughness and improving surface quality.

Porous titanium alloy implants with simulated trabecular bone fabricated by 3D printing technology have broad prospects. However, due to the fact that ...

Quasistatic Load-to-Fracture Test of CAD/CAM Occlusal Veneers on Dentin Analogs

Quasistatic Mechanical Testing for Computer-Aided Design and Manufacturing Occlusal Veneers Cemented to Milled Dentin Analog Material

Under current minimally invasive treatment regimes, minor tooth preparation and thinner biomimetic ceramic restoration are used to preserve the restored tooth&#39;s vitality, aesthetics, and function. New computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic-like material are&#160;now available. To guarantee longevity, a dental clinician must know these&#160;newly launched product&#39;s mechanical strength compared to the relatively brittle glass-matrix ceramic. Furthermore, a tooth substitute has been promoted for laboratory investigation, especially after the pandemic, and more evidentiary support is required for its application.
This study developed a laboratory protocol for a monotonic load-to-fracture test to determine the fracture strength of 1 mm-thick CAD/CAM occlusal veneers. Master dies were milled from high-pressure fiberglass laminate, which has&#160;similar elastic modulus and bond strength as hydrated dentin. They were mounted into polyvinyl chloride (PVC) end caps with cold-curing epoxy resin. Occlusal veneers, also called tabletop restorations, were milled from lithium disilicate (LD) and resin nanoceramic blocks (RNC) and cemented to prepared master dies using dual-cured adhesive resin cement. They were&#160;allowed to cure fully by storing in distilled water for 48 h at 37 &#176;C.
All samples were then placed in a universal testing machine and loaded via a non-fixed 5.5 mm stainless-steel ball that allows lateral movement as would occur against the antagonist&#160;teeth. Compression was applied at a 1 mm/min rate, and the load-displacement graph was generated. The average maximum load-bearing capacity of restorations in the RNC group (3,212.80 &#177; 558.67 N) was significantly higher than in the LD group (2727.10 &#177; 472.41 N) (p &#60; 0.05). No debonding was found during the test.&#160;Both CAD/CAM materials may have a similar flaw distribution. Hertzian cone crack was found at the loading site, whereas radial cracks propagating from the cementation surface were found close to the margin in both groups.

A quasistatic load-to-fracture test with a non-fixed stainless steel ball was developed to determine the fracture strength of minimally invasive posterior computer-aided design and manufacturing restorations cemented to dentin analog materials. This test models the typical loading regime responsible for the fracture of dental restorations.

Under current minimally invasive treatment regimes, minor tooth preparation and thinner biomimetic ceramic restoration are used to preserve the restored ...

Impact of Fabrication Techniques and Polishing Procedures on Surface Roughness of Denture Base Resins

This study aimed to assess the impact of various fabrication techniques and polishing procedures on the surface roughness (Ra) of resin-based materials used in the fabrication of complete dentures. A total of 90 specimens were produced from three different resin materials: heat-polymerized polymethyl methacrylate (PMMA) resin, CAD-CAM milled PMMA resin, and 3D-printed resin (n = 30). Each specimen measured 10 mm in diameter and 2 mm in height. The surface roughness (Ra) values of the specimens were initially determined using a contact profilometer following fabrication. Subsequently, each group of specimens was polished with 600-, 800-, and 1000-grit silicon carbide abrasive papers under running water. A second measurement of the surface roughness (Ra) values was then performed. The data were analyzed statistically using the Kruskal-Wallis test, Mann-Whitney U test, Wilcoxon signed-rank test, and paired samples t-test (p = 0.05). A statistically significant difference was identified between the groups in terms of surface roughness (Ra) prior to the polishing process (p &#60; 0.001). However, no statistically significant difference was observed between the milled and heat-polymerized PMMA base materials following the polishing process. The 3D-printed specimens showed the most notable improvement in surface roughness due to the polishing process. Nevertheless, their surface roughness remained statistically significantly higher compared to the other samples, both before and after polishing (p &#60; 0.001). The fabrication method of complete denture base materials was observed to influence surface roughness. The surface roughness values of the base materials fabricated using the 3D printing method were higher compared to those fabricated with milled and heat-polymerized PMMA resin, both before and after polishing.

This article presents a protocol to evaluate the effects of different manufacturing methods (heat-polymerized PMMA, CAD-CAM milled PMMA, and 3D-printed resin) and polishing techniques (600, 800, and 1000 grit silicon carbide abrasive papers) on the surface roughness (Ra) of resin base materials used for complete dentures.

This study aimed to assess the impact of various fabrication techniques and polishing procedures on the surface roughness (Ra) of resin-based materials ...

Effects of Mechanical Methods Used in Peri-implantitis Treatment on Implant Surface Decontamination and Roughness

Various mechanical methods have been proposed for decontaminating dental implant surfaces with varying success. This in vitro study evaluated the decontamination efficiency of an air abrasion (AA) system with erythritol powder, a polyether-ether-ketone (PEEK) ultrasonic tip, and titanium curettes (TIT) and their effects on implant surface topography using scanning electron microscopy (SEM). A total of 60 implants were stained with permanent red ink and placed in 3D-printed Class 1A and Class 1B peri-implantitis defects, forming six groups (n=10 per group) based on defect type and treatment protocol. Additionally, one positive and one negative control implant was used. Erythritol powder, PEEK ultrasonic tips, and titanium curettes were applied for 2 min in Class 1A defects and 3 minutes in Class 1B defects. Residual red ink areas were quantified with digital software, and implant surface changes were analyzed using SEM and EDS. None of the methods achieved complete decontamination. However, erythritol powder was significantly the most effective, leaving a residual ink rate of 24% &#177; 6% (p &#60; 0.001). PEEK ultrasonic tips resulted in 41% &#177; 4% residual ink, while titanium curettes left 55% &#177; 3%. Significant differences were observed among all methods. No significant difference in decontamination efficacy was found between Class 1A and Class 1B defects. SEM analysis showed minimal surface damage with erythritol powder and PEEK tips, whereas titanium curettes caused moderate to severe damage. Based on both decontamination efficiency and surface preservation, erythritol powder and PEEK tips are safe and effective options for peri-implantitis treatment, while titanium curettes are less effective and cause considerable surface damage. These findings may assist clinicians in peri-implantitis treatment planning.

The present protocol describes an experimental model based on ink-staining which can be used for in vitro implant surface decontamination and roughness research to contribute to clinical decision-making.