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Article

Effect of Different Finishing Systems on Surface Roughness and Gloss of a 3D-Printed Material for Permanent Dental Use

by
Alessandro Vichi
*,
Dario Balestra
and
Chris Louca
Dental Academy, University of Portsmouth, Portsmouth PO1 2QG, UK
*
Author to whom correspondence should be addressed.
Appl. Sci. 2024, 14(16), 7289; https://doi.org/10.3390/app14167289
Submission received: 21 July 2024 / Revised: 14 August 2024 / Accepted: 15 August 2024 / Published: 19 August 2024
(This article belongs to the Special Issue Advanced Materials for Polymeric 3D Printing Applications)
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Abstract

:

Featured Application

Few or no finishing systems are specifically available for 3D printable materials for permanent dental restorations. The generic systems tested in this study were generally able to give clinically acceptable results for roughness. Conversely, the outcome was poor for gloss, except for curing in a nitrogen chamber unit. The results suggest the need to develop finishing/polishing systems dedicated to this specific category of prosthetic materials.

Abstract

The object of the study was to assess the effect of different finishing and polishing systems on the roughness and gloss of a 3D-printed permanent restorative material. One 3D printable Permanent material was selected for the study. Squared-shaped specimens (14 mm2; 5 mm thickness) were obtained by designing and printing. Eighty specimens were produced and randomly assigned (n = 10) to 8 finishing and polishing methods: Sof-Lex™ Spiral Wheels (SW), Sof-Lex™ XT Pop-on Disc (SD), Identoflex Lucent no paste (Ln), Identoflex Lucent + paste (Lp), Resin Nitrogen polymerized (NG), Optiglaze (OG), Opti1Step (OS), and HiLusterPLUS (HL). Surface roughness and gloss were then measured by a roughness meter and a glossmeter, respectively. For roughness, statistically significant differences were found (p < 0.001), with NG(a) > SD(b) = OG(b) = Lp(b); Lp(b) = Ln(bc); Ln(bc) = OS(cd); OS(cd) = SW(de); and SW(de) = HL(e). For gloss, statistically significant differences were also identified (p < 0.001) with NG(a) > SD(b) > Lp(c) = OS(c) = OG(cd); OG(cd) = Ln(d) > HL(e) = SW(e). The nitrogen chamber polymerization showed better results for both roughness and gloss. Multi-step finishing/polishing systems were able to produce smoother surfaces than 1-step and 2-step systems.

1. Introduction

The objective of restorative dentistry is to replicate the dental structures both functionally and aesthetically. Adhesive techniques have developed over the years to allow for minimal intervention on the tooth [1,2]. Most restorative materials can be adhesively cemented, among which resin composite materials have greatly improved over time [3,4,5]. Direct anterior and posterior restorations can be placed directly with adhesive systems and resin composites due to their mechanical and optical properties [6,7], which are increasingly growing similar to the natural tissues [8,9,10]. Alternatively, these materials can be used indirectly, with the restoration created out of the mouth on a model, then cured, obtaining a higher degree of conversion, and finally adhesively cemented. In addition to these “manual” direct and indirect techniques, digital dentistry has developed in the last few years. The general purpose of the CAD/CAM procedure is to design the restoration with a CAD process over a virtual model and produce the restorations with a CAM process [11]. CAD/CAM resin composite blocks for milling were introduced in early 2000 and are increasingly used [12,13]. Along with milling, which still represents the state of the art for producing digital restorations, more recently, a growing technology is the possibility of 3D print CAD-designed restorations [14,15,16]. Processes like Stereolithography (SLA) and Digital Light Projection (DLP) are becoming progressively familiar to dentists and dental technicians. Both processes use light—laser for SLA and LED for DLP—to polymerize targeted areas with clinically suitable ‘precision’. While 3D printing of ceramic in dentistry is still in its infancy, the use of resin is widespread, and recently, resin products for permanent restorations have been developed and marketed. In the 3D printing process, the resin has to flow into the tank, and for this reason, the current possibility of loading the resin with the inorganic filler at a direct/indirect composite level is precluded.
It has been reported that the physical characteristics of 3D-printed resins are comparable to flowable composite [17]. To complete the process, after 3D-printing, the restoration, a cleaning procedure to remove the uncured portions of the printed object/restoration and a post-curing process to increase the degree of conversion need to be carried out. When restoration is ready after post-curing, it still lacks some surface characteristics, such as optimal gloss and roughness, and requires a final finishing and polishing (F&P) step to meet the clinical standards. In most cases, the manufacturer indicates nonspecific F&P systems for these materials, and manufacturer guidance often refers to a “standard procedure for polishing and finishing traditional composite”.
Polishability is an important property for dental materials, and surface properties such as roughness and gloss significantly influence the clinical outcome of the restorations [18]. Surfaces not adequately finished and polished are more susceptible to plaque accumulation, wear, increased risk of staining and secondary caries, and may concur in increased gingival inflammation [19,20], associated with possibly reduced clinical success [21,22,23]. Moreover, restorations with smoother surfaces are more comfortable for the patient and more aesthetically pleasing [24,25].
The aim of this study was to evaluate the surface roughness and gloss of a 3D-printed resin for permanent restorations. Several different procedures were used. Each was representative of the most commonly used systems for in-office and laboratory F&P systems, ranging from clinical systems with silicone points with decreasing granulometry that can be used at the chairside to a similar silicon laboratory used when the restoration is produced by the dental technician, as well as resin-glazing systems including a recently developed procedure that uses a nitrogen curing device. The null hypothesis was that the performed F&P procedures do not influence the surface roughness and gloss of the currently available 3D-printed resins for permanent use.

2. Materials and Methods

Square-shaped specimens with a dimension of 14 mm × 14 mm and 5.0 mm in thickness were designed with Tinkercad software (Autodesk, San Rafael, CA, USA) (Figure 1).
The file was then exported in .stl format and uploaded into PreForm 3 software (Formlabs, Somerville, MA, USA). The support calculation was performed in “automatic” mode (Figure 2), and then the slicing process was performed.
The parameters for printing were set to a 50-layer thickness. The exposure time used was provided by the software for Permanent Crown 3DP resin (Table 1).
Specimens were 3D printed with the Formlabs 3B+ 3D printer (Formlabs, Sommerville, MA, USA). After printing, specimens were removed from the printing platform and, with still raft and supports intact, were subjected to the washing procedure for 3 min with the FormWash (Formlabs, Somerville, MA, USA), using 99% Isopropyl Alcohol (IPA) to remove the uncured resin. After washing, the specimens were additionally cured for 20 min at 60 °C in the FormCure (Formlabs, Somerville, MA, USA). Following manufacturer instructions, the specimens were then sandblasted with 50 μ glass=bead blasting material (Perlablast micro, Bego, Bremen, Germany) at a pressure of 1.5 bar to remove the filler particles layered onto the surface and then post-cured again in the FormCure for another 20 min at 60 °C. Finally, the specimens were marked for recording printing orientation and removed from the rafts.

2.1. Surface Roughness Measurement

Before testing, specimens were ultrasonically cleaned in a 95% ethanol solution for 3 min. A profilometer (Mitutoyo SJ-201P, Mitutoyo, Kanagawa, Japan) was used to assess surface roughness (Ra), with a cutoff value set at 0.8 mm, a stylus speed of 0.5 mm/s, and a tracking length of 5.0 mm. The measurement setup was standardized using a custom-made mold for both the handpiece of the instrument and the specimens. All the specimens were measured in the same direction with respect to printing. Mean Ra (μm) was recorded.

2.2. Surface Gloss Measurement

The gloss measurements were made using a gloss meter (JND- XA6-SA; VTSYIQI Lab Measuring Instruments, Hefei, China) with a measurement area of 2 mm × 2 mm. Gloss assessment was performed at a 60° angle. A proprietary grey mold was used to avoid any possible influence of ambient light and to position the specimen so that the gloss meter reading area was in the same central area as the specimens. The GU (Gloss Unit) values were recorded.
After measurements, specimens were randomly divided into 8 groups (n = 10) according to F&P procedures. The procedures are described in Table 2.

2.3. Statistical Analysis

2.3.1. Roughness

To statistically analyze the first formulated null hypothesis, a one-way (ANOVA) was applied after having preliminarily the normal distribution (Shapiro–Wilk test) and the homogeneity of variances (Levene test). For post hoc comparisons, the Tukey test was applied.

2.3.2. Gloss

After checking the normality of data distribution (Shapiro–Wilk test) and the homogeneity of variances (Levene test), a one-way analysis of variance (ANOVA) followed by Tukey’s test was applied to gloss measurement to test the second formulated null hypothesis.
The level of significance was set at p < 0.05 in all the statistical tests. SigmaPlot 11.0 software (Systat Software Inc., San Jose, CA, USA) was used for statistical calculations.

2.4. SEM Observation

The specimens for SEM observations were preliminarily cleansed in an ultrasonic bath in a 95% alcohol solution for 3 min and air-dried with an oil-free air spray. Specimens were then secured onto SEM slabs with gold conducting tape and gold-coated in a vacuum sputter coater (Quorum Q150R sputter coater, Quorum Technologies, Laughton, UK). SEM Observation was carried out in a MIRA 3 FEG-SEM (Tescan, Brno, Czech Republic) at 400× magnification for morphological evaluation.

3. Results

3.1. Surface Roughness

The descriptive statistics of surface roughness data are reported in Table 3.
The One-Way ANOVA showed that NG had a significantly lower roughness than the other materials, followed by SD, OG, Lp, and Ln, and the difference was statistically significant (p < 0.001). HL showed the highest roughness even if no statistically significant differences were found with SW.

3.2. Surface Gloss

The descriptive statistics of the surface gloss data are reported in Table 4.
The one-way ANOVA post hoc comparisons revealed that NG had the highest gloss followed by SD, and the difference was statistically significant (p < 0.001); also, HL and SW exhibited a statistically significant lower gloss than the other systems tested.

3.3. SEM Evaluation

Different surface topographies were observed for the different polishing systems (Figure 3). O1 and HL showed surfaces with roundish depressions, typical of the finishing and polishing procedure performed with points, while HL showed the same round depressions but slightly better defined. A very similar surface was observed for SW, even if some superficial scratches were also present. SD showed some linear depressions instead. Since the result of SD in terms of roughness was quite favorable, it can be speculated that the linear depressions observed are of a low depth, scarcely influencing roughness measurement. When a laboratory F&P system is used, the result is similar but smoother than the clinical systems. The additional use of a finishing paste resulted in a noticeably smoother surface. The use of OG, a resin addressed to an in-office (chairside) glaze, made the surface quite smooth, but with some scratches that can still be identified even if they look partially filled by the resin. The nitrogen-glazed group showed the most homogeneous surface, with depressions or scratches that were almost not visible. The SEM observation of this group relates well to the findings of the study.

4. Discussion

Several systems for F&P of resin composites are currently available, and some data are available in the literature. They are quite different in terms of methods (disc, point, wheels, paste, resin), steps (1 to 4), use (in office/chairside, laboratory), and required equipment (micromotor, lab motor, clinical curing light, laboratory curing light in oxygen or nitrogen environment), whereas the effects of these F&P systems on the roughness and gloss of direct and indirect resin composites such as conventional hybrid, nano-hybrid, and bulk fill composites have been investigated [26,27,28,29,30,31,32,33]. So far, few investigations have been performed researching the effects of F&P procedures on 3DP resin composite materials for permanent use. F&P procedures are of utmost importance for these materials, as the 3DP layering process can lead to rough surfaces. In the present study, the effects of different F&P systems on the roughness and gloss of one 3DP resin composite material for permanent restorations have been investigated, selecting eight different procedures with different workflows. The data obtained in the present study suggest rejection of the null hypotheses as the performed F&P procedures significantly influenced the surface roughness and gloss of 3DP resin composites.
Roughness and gloss are important surface properties of dental restorative materials. Roughness is linked to surface unevenness, and it is generally measured in terms of roughness average (Ra), which has been defined as the “mean arithmetical value of all the absolute distances of the profile inside of the measuring length” [34]. Gloss is conversely an optical property measured in gloss units (GU) correlated with specular reflection from a surface, and it is responsible for shiny or mirror-like appearance [35,36]. Gloss is influenced by the reflection of light from a surface, but for composite resins, it is also influenced by the refractive indices of the resin matrix and filler [37] and by filler size and filler-matrix similarity, observing that the lower the filler-matrix homogeneity, the lower the light reflectivity [38]. An inverse linear relationship between roughness and gloss has been reported in previous studies [31,39,40], and this is corroborated by the present one.
Since the goal of an F&P procedure is to provide a surface that matches its range enamel, the final roughness of the composite restorative material should be ideally similar to enamel roughness (0.45 µm/0.64 µm) [41]. In the present study, the roughness measured ranged from 0.25 µm to 0.83 µm. Therefore, not all the F&P systems were able to provide enamel-like results. Statistically significant differences emerged among the various systems tested. In particular, HL showed the highest Ra, even if no statistically significant differences were found with SS. It should be noted that all the manual 1- or 2-step systems showed the worst results, with only OS not statistically significantly different from a laboratory system used without polishing paste. The use of the polishing paste showed a tendency to improve the polishability both for Ra and SEM observation, but this tendency was not statistically significant.
No statistically significant differences in roughness emerged among SD, GL, LP, and LN. SD, a direct 4-step system, showed statistically significantly better results than all the other direct systems, OS, SW, and HL.
The use of a resin directly layered onto the surface of the restoration (of the specimens in the present case) followed by a polymerization carried out in a curing unit with a nitrogen environment showed a mean Ra of 0.25 µm—thus a very smooth surface, and smoother than the reference enamel range, and statistically significantly better than all the other systems.
Some references are available in the literature for the evaluation of roughness. Concerning plaque retention, the reference value reported in the literature for Ra is 0.20 µm [22,42]. In this regard, only the group in which a resin layer was polymerized in a curing unit with nitrogen was able to obtain a Ra value close to this threshold. Tongue sensitivity, which is the capability of the tongue to perceive the roughness of a restoration, has been reported as 50 µm. For this threshold, several systems tested were below or close to this threshold. Only OS, SW, and HL showed a Ra well above the referenced value. The Ra value over which a restoration is considered to generate wear on the antagonist is reported to be 1.50 µm [43]. All the tested systems were able to finish/polish the surfaces well below this limit. The results of the various materials compared with the reference values are reported in Figure 4.
Similarly to roughness, the F&P procedures are also aimed at providing an enamel-like gloss. This value has been reported to be 53 GU by Mormann et al. [44], while Barucci-Pfister et al. [45] indicated the final gloss of a resin composite to be in the range of 40–53 GU. All these values should be cautiously evaluated, as no agreement has been achieved in the literature on the measuring setup for gloss, particularly concerning the geometry of viewing. This fact determines a lack of uniformity among different studies and makes a direct comparison of the findings not completely reliable. Some authors reported that a 20° viewing geometry angle enables an improved differentiation compared with a 60° angle [46], while other authors reported the 45° angle as the ideal geometry [46]. Cook and Thomas [47], using a 60° measurement angle considered closer to the surface observation angle by an average person, reported a classification where they defined as “poor” a finishing below 60 GU, as “acceptable” a finishing in the range of 60–70 GU, as “good” a finishing in the range of 70-80 GU and as “excellent” a finishing above 80 GU. In the present study, in agreement with Cook and Thomas and also following the technical report of ISO 2813-2014 [48], a 60° geometry was used. Therefore, according to the reported classification, all the F&P systems tested achieved a “poor” finishing in terms of gloss, with the only exception of the NG group, which obtained a mean of 90.7 GU. This value, together with showing a statistically significant difference with all the other systems tested, makes NG the only group that could be classified as “excellent”. It should be pointed out that as the paper by Cook and Thomas is not a clinical dental paper, an “exceeding” GU value had not been considered. This should probably be taken into consideration as if an opaque surface differs from human enamel, a mirror-like surface would probably also show a non-natural outcome (Figure 5).
The present study evaluated eight different F&P systems quite different from each other in terms of steps, procedures, and equipment. Therefore, the ease of use and time-related aspects should also be mentioned. SS showed good results, being only after the NG system in terms of gloss and roughness, but it should be noted that a 4-step procedure with disks is time-consuming, and it is commonly used only for anterior restorations, as disks are difficult to use on occlusal surfaces. Whilst a chairside approach is time-saving, without the need for additional laboratory steps, there is still little indication about the ideal F&P procedure, as the advantages of an in-office procedure might be counterbalanced by a time-consuming manual procedure. In the present study, the 4-step disc system SS showed statistically significantly better results for both roughness and gloss than all the 1-step (O1) and the 2-step systems (SS, HL, LN, and LP).
Another aspect to be considered is that most of the F&P procedures tested are subtractive, with the exception of OG and NG, which are additive. In these procedures, a resin layer is applied to the surface, possibly influencing the thickness. This does not affect the Roughness and Gloss measurements performed in the present study as they are surface measurements, but it should be taken into due consideration in clinical conditions, with the applied resin layer that could be worn by chewing and/or physical and chemical agents.
A limitation of the present study, and a possible subject for future investigations, is that only one permanent material for 3DP was tested and printed with only one 3D printing system, resulting in only one initial roughness (1.56 μm, mean of all the specimens before treatment) and gloss (3.2 GU, mean of all the specimens before treatment), and it is known that the initial roughness affects the outcome [49]. Therefore, testing different materials and different printing systems could give more comprehensive results for F&P 3DP composite resins for permanent restorations. The stability over time of the initially achieved results (e.g., after function and/or brushing) should also be the object of future studies, as there is scarce or absent information on this issue for this category of materials.

5. Conclusions

  • The combination of the tested 3DP resin for permanent use and the eight finishing and polishing systems were able to achieve clinically acceptable results for roughness, while less acceptable results were obtained for gloss. The only exception was the nitrogen-glazed option, which achieved excellent results for both roughness and gloss.
  • Multi-step finishing/polishing systems showed a higher polishing ability on 3DP resin for permanent use than the 1-step and 2-step systems.
  • The use of the additional polishing paste in the laboratory 2-step manual system did not improve the result for roughness, but it did for gloss.
  • The nitrogen-glazed system showed better results in terms of roughness and gloss than all the other systems tested.

Author Contributions

Conceptualization, A.V. and D.B.; methodology, A.V.; software, A.V.; formal analysis, A.V.; investigation, D.B.; writing—original draft preparation, A.V.; writing—review and editing, C.L.; supervision, A.V. and C.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author. The data are not publicly available due to the university policy on access.

Acknowledgments

The authors thank Formlabs GmbH, Belin, Germany, for donating the printing materials and Yen co. S.r.l., Pieve di Soligo (TV), Italy, for making the nitrogen chamber curing unit accessible.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Specimens designed with Tinkercad software.
Figure 1. Specimens designed with Tinkercad software.
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Figure 2. Specimens’ automatic support calculation.
Figure 2. Specimens’ automatic support calculation.
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Figure 3. SEM observations (400×) of the eight systems tested. OS (1), HL (2), and SW (3) showed roundish depressions. SD (4) showed linear depressions. Lp (5) and Ln (6) also showed linear depressions, but they were smaller than SD and less visible in Lp than in Ln. OG (7) showed scratches partially filled by the resin. NG (8) showed a quite homogeneous surface with depressions or scratches almost not visible.
Figure 3. SEM observations (400×) of the eight systems tested. OS (1), HL (2), and SW (3) showed roundish depressions. SD (4) showed linear depressions. Lp (5) and Ln (6) also showed linear depressions, but they were smaller than SD and less visible in Lp than in Ln. OG (7) showed scratches partially filled by the resin. NG (8) showed a quite homogeneous surface with depressions or scratches almost not visible.
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Figure 4. Mean Ra of the tested groups compared with non-treated specimens mean and literature reference values for enamel, plaque retention, tongue sensitivity, and antagonist wear.
Figure 4. Mean Ra of the tested groups compared with non-treated specimens mean and literature reference values for enamel, plaque retention, tongue sensitivity, and antagonist wear.
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Figure 5. The mean Ra of the tested groups compared with non-treated specimens mean and literature reference values for the evaluation of the effectiveness of gloss according to Cook and Thomas [47].
Figure 5. The mean Ra of the tested groups compared with non-treated specimens mean and literature reference values for the evaluation of the effectiveness of gloss according to Cook and Thomas [47].
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Table 1. Chemical composition of the tested 3DP permanent material.
Table 1. Chemical composition of the tested 3DP permanent material.
MaterialsTypeOrganic MatrixInorganic Filler ManufacturerShadeLot
Permanent
Crown
Resin		Methacrylic
acid
ester-based
resin		≥50–<75% wt.
Bis-EMA		Silanized dental glass
(30–50% wt.)		Formlabs Inc.,
Somerville, MA, USA		A2600163
Bis-EMA—bisphenol-A-ethoxylate dimethacrylate.
Table 2. Chemical composition and instructions for the use of tested finishing/polishing systems.
Table 2. Chemical composition and instructions for the use of tested finishing/polishing systems.
MaterialAbbreviationTypeDescriptionApplication
Opti1Step Polisher FlameOS1 stepSilicone rubber (polyvinylsiloxane), silicon carbide, aluminum oxide, silicon oxide, diamond.20 s using a low-speed handpiece in circular movements and with continuous water cooling (50 mL/min)Kerr Corporation, Orange, CA, USA
HiLusterPLUS Polisher FlameHL2 stepsPoints with integrated aluminum oxide particles (1st step) and diamond particles integrated (2nd step).20 s each using a low-speed handpiece in circular movements and with continuous water cooling (50 mL/min)Kerr Corporation, Orange, CA, USA
Sof-Lex™ Spiral WheelsSW2 stepsSpiral finishing and polishing wheels—thermoplastic elastomer impregnated with aluminum oxide particles (pink and white).20 s each using a low-speed handpiece in circular movements and with continuous water cooling (50 mL/min)3M/ESPE, St. Paul, MN, USA
Sof-Lex™ XT Pop-on DiscSD4-stepFinishing and polishing discs made from urethane-coated paper covered with
aluminum oxide.		20 s each using a low-speed handpiece in circular movements and with continuous water cooling (50 mL/min)3M/ ESPE, St. Paul, MN, USA
Lucent point
(PVE, PGR, PVI)		Ln3-step labAbrasive powder with a silicon binding.20 s each using a low-speed handpiece in discontinuous movements without water cooling Kerr Corporation, Orange, CA, USA
Lucent point (PVE, PGR, PVI)
Unipolish		Lp3-step lab plus pasteAbrasive powder with a silicon binding
Paste: pumice in a variable dimension.		20 s each using a low-speed handpiece in discontinuous movements without water cooling followed by paste application in two steps: hard and soft bristle brushesKerr Corporation, Orange, CA, USA
OptiglazeOGLiquidNanofilled Light-cured protective coating.Applied with a microbrush in 1 layer and cured for 3 min in a Lab curing unit (Labolight LV-III)GC Co., Tokyo, Japan
Nitrogen Cured resinNGLiquidMethacrylic
acid
ester-based
resin.		Applied with a brush in a thin coat. Curedin the Graphy Cure THC 2 for 15 min. at level 2, with nitrogen.Graphy Inc., Seoul, Republic of Korea
Table 3. Descriptive statistics of surface roughness (Ra, μm). Lowercase letters label statistically significant differences among the finishing systems (p < 0.05).
Table 3. Descriptive statistics of surface roughness (Ra, μm). Lowercase letters label statistically significant differences among the finishing systems (p < 0.05).
TreatmentRoughness (µm)
Crown Permanent
MeanSDSign.
NG0.250.05a
SD0.440.16b
OG0.460.03b
Lp0.520.16b
Ln0.590.13bc
OS0.730.12cd
SW0.770.12de
HL0.830.20e
Table 4. Descriptive statistics of surface gloss (GU). Lowercase letters label statistically significant differences among the finishing systems (p < 0.05).
Table 4. Descriptive statistics of surface gloss (GU). Lowercase letters label statistically significant differences among the finishing systems (p < 0.05).
TreatmentGloss (GU)
Crown Permanent
MeanSDSign.
NG90.71.3a
SD51.79.7b
Lp38.110.0c
OS35.37.7c
OG30.50.8cd
Ln27.70.9d
HL18.56.0e
SW12.92.6e
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Vichi, A.; Balestra, D.; Louca, C. Effect of Different Finishing Systems on Surface Roughness and Gloss of a 3D-Printed Material for Permanent Dental Use. Appl. Sci. 2024, 14, 7289. https://doi.org/10.3390/app14167289

AMA Style

Vichi A, Balestra D, Louca C. Effect of Different Finishing Systems on Surface Roughness and Gloss of a 3D-Printed Material for Permanent Dental Use. Applied Sciences. 2024; 14(16):7289. https://doi.org/10.3390/app14167289

Chicago/Turabian Style

Vichi, Alessandro, Dario Balestra, and Chris Louca. 2024. "Effect of Different Finishing Systems on Surface Roughness and Gloss of a 3D-Printed Material for Permanent Dental Use" Applied Sciences 14, no. 16: 7289. https://doi.org/10.3390/app14167289

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