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

Summary

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.

Abstract

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 < 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.

Introduction

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 materials^3,4,5. 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. Arabacı 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 materials^6,7. 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 materials^6,8,9,10. 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 investigations^{3,13,14,15,16}. 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.

Protocol

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.'s study¹⁷ parameters (mean defect depth difference (Ra; µm): 15, standard deviation (µm): 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

1. 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).
2. 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).
3. 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.
4. 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.
5. 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.

2. Stabilization of the samples into acrylic blocks

1. 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.
2. 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).
3. 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).
4. 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).
5. 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: λc = 0.8, λs = 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).
6. 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's average roughness (Ra) using a contact profilometer.
7. Verify the readings using the designated locations of each specimen (middle top). For each reading, move the device'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.

3. Creating the setup for the scaler application

1. Obtain a parallelometer (Figure 6A). Fix the acrylic block on the table of the parallelometer (Figure 6B, C).
2. 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).
3. 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°, at maximum power, under water cooling, and with equal force on a specified designated region (Figure 8A, B, C, D).
4. Following the scaler application, repeat the profilometric measurements and the scanning electron microscope imaging for each sample (Figure 9A,B).

Results

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 < 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...

Discussion

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 effect^8,9. 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 ...

Materials

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