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Article

Morpholine’s Effects on the Repair Strength of a Saliva-Contaminated CAD/CAM Resin-Based Composite Mended with Resin Composite

by
Awiruth Klaisiri
1,*,
Tool Sriamporn
2,*,
Nantawan Krajangta
1 and
Niyom Thamrongananskul
3
1
Division of Restorative and Esthetic Dentistry, Faculty of Dentistry, Thammasat University, Pathum Thani 12120, Thailand
2
Department of Prosthodontics, College of Dental Medicine, Rangsit University, Pathum Thani 12000, Thailand
3
Department of Prosthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330, Thailand
*
Authors to whom correspondence should be addressed.
J. Compos. Sci. 2025, 9(7), 345; https://doi.org/10.3390/jcs9070345
Submission received: 10 June 2025 / Revised: 28 June 2025 / Accepted: 30 June 2025 / Published: 2 July 2025
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Abstract

The objective of this study was to evaluate the effect of morpholine on saliva-contaminated resin-based composite (RBC)-CAD/CAM material repaired with resin composite. Fifty RBC-CAD/CAM materials were fabricated and assigned to five groups and surface-treated with saliva, phosphoric acid (PHR), morpholine (MRL), and a universal adhesive agent (Scotchbond universal plus, SCP) based on the following techniques: group 1, saliva; group 2, SCP; group 3, saliva + SCP; group 4, saliva + PHR + SCP; and group 5, saliva + MRL + SCP. An ultradent model was placed on the specimen center, and then the resin composite was pressed and light-cured for 20 s. A mechanical testing device was used to evaluate the samples’ shear bond strength (SBS) scores. The debonded specimen areas were inspected under a stereomicroscope to identify the failure mechanisms. The data were analyzed using one-way ANOVA, and the significance level (p < 0.05) was set with Tukey’s test. The highest SBS values were in groups 2, 4 and 5, with values of 21.43 ± 1.93, 20.93 ± 1.46, and 22.02 ± 1.77 MPa, respectively. However, they were not statistically different (p > 0.05). Group 1 had the lowest SBS value by a significant amount (1.88 ± 1.01 MPa). All specimens in group 1 showed adhesive failures. Moreover, groups 2–5 found cohesive and mixed failures. In conclusion, morpholine and phosphoric acid effectively enhance bond strength. These results indicate that alternative surface modifications with morpholine for saliva-contaminated RBC-CAD/CAM materials can significantly improve the outcome.

1. Introduction

Advancements in dental computer-aided design/computer-aided manufacturing (CAD/CAM) technology and enhancements in ceramic physical properties have enabled the fabrication of indirect restorations using novel materials, including silica-based ceramics, zirconia, and recently introduced resin-matrix ceramics [1]. These ceramic materials exhibit variations in their physical structure, chemical composition, and characteristics. Resin-matrix ceramics (RMCs) are a new family of CAD/CAM materials characterized by a composite resin-matrix structure [2]. This material combines the advantages of polymers (such as reduced antagonist wear and enhanced flexural characteristics) with ceramics (such as structural durability and color stability) [2,3,4]. The categorization of polymeric CAD/CAM materials depends on their microstructure and the industrial polymerization methods used to produce polymer-infiltrated ceramic networks (PICNs) and resin-based composites (RBCs) [5].
PICNs are distinguished by the infiltration of a cross-linked polymer into the porous networks [2,6]. The interconnected polymer network’s dual network topology effectively reduces fracture propagation and enhances the mechanical properties of the ceramic [7]. The use of PICNs has shown excellent outcomes in two research trials, with a 3-year survival rate ranging from 97.0% to 97.4% for partial coverage operations [8,9]. The RBC-CAD/CAM is composed of a polymeric matrix reinforced with nanoceramic or nanohybrid ceramic fillers [6,10]. The elastic modulus of this material is similar to dentin, and it has been shown to have outstanding flexural strength and internal discrepancy in comparison to lithium disilicate ceramics [6,10]. However, these materials have several limitations, including discoloration, low wear resistance, and weak fracture strength [11]. The surface modifications of RBC-CAD/CAM are one important factor that influences the adhesion of resin materials. In previous studies, the chemical surface treatment of RBC-CAD/CAM with universal adhesive was found to be effective for resin materials [12,13]. However, there is insufficient research on the surface modifications of saliva-contaminated RBC-CAD/CAM.
Saliva contamination is a critical factor for dental material adhesion. Saliva-contaminated substances can reduce the bonding ability of other substances [14,15]. Previous studies found that saliva-contaminated substances have an effect on impaired shear bond strength compared to non-saliva contamination [16,17]. Phosphoric acid etching is one method used to clean saliva contamination from resin composite and acrylic resin surfaces [16,17]. On the contrary, Komagata et al. reported that phosphoric acid cannot eliminate saliva contamination on porcelain surfaces [18]. Additionally, many studies reported that morpholine can decontaminate saliva on resin composite and acrylic resin surfaces when applied to saliva-contaminated surfaces without the water rinse [16,17]. The structure of morpholine is of great interest in the field of medicinal chemistry due to its presence in several pharmaceuticals and physiologically active substances [19]. Previous research in dentistry used morpholine as a saliva decontaminant in resin composite, acrylic resin, and a surface treatment agent for fiber-reinforced posts [16,17,20].
However, there is a lack of evidence about the effectiveness of morpholine as a surface alteration to enhance the repair bonding capacity between saliva-contaminated RBC-CAD/CAM material and resin composites. This study was initiated to address this gap in knowledge. The objective of this study was to evaluate the effect of morpholine on saliva-contaminated RBC-CAD/CAM material repaired with resin composite by evaluating their shear bond strengths (SBSs). We hypothesize that the application of morpholine does not significantly affect the SBS between saliva-contaminated RBC-CAD/CAM material and resin composite.

2. Materials and Methods

2.1. Procedures for Preparing RBC-CAD/CAM Specimens

The RBC-CAD/CAM materials, manufactured by Shofu Inc., Kyoto, Japan, were precisely cut into fifty pieces, each measuring 6 × 7 mm2 and having a thickness of 1.5 mm. The RBC specimens experienced aging using a thermocycling unit (SD-Mechatronik, Westerham, Germany) involving 5000 temperatures ranging from 5 °C to 55 °C. Each cycle had a rest time of 30 s and a transfer time of 5 s [12]. A polyvinyl chloride (PVC) tube filled with epoxy resin was used to contain the RBC-CAD/CAM specimens (Figure 1). The surface texture of the RBC-CAD/CAM was standardized by sanding them with a 600-grit silicon carbide abrasive (3M abrasive sheet, St. Paul, MN, USA). All samples received a 10 min cleaning in distilled water using an ultrasonic cleaner. The materials used in the current study are outlined in Table 1.

2.2. Sandblast Process

The specimens were subjected to sandblasting using 50-micron aluminum oxide particles spaced at a distance of 10 mm for 10 s under 2 bar pressure [12]. Following the sandblasting process, the specimens were washed and then allowed to dry normally for 10 s using a triple syringe.

2.3. Surface Treatment Specimens Grouping

The samples were randomly divided into five groups, each containing 10 samples (n = 10 per group). The sandblasted RBC-CAD/CAM samples were surface-treated using saliva, phosphoric acid, morpholine, and a universal adhesive agent (Singlebond universal plus (SCP), 3M, Neuss, Germany) according to the specified procedures (Table 2).

2.3.1. Artificial Saliva Contamination

The RBC-CAD/CAM surface was rubbed with 100 microliters of synthetic saliva (Biotene, Haleon plc., Weybridge, UK; water, glycerin, xylitol, sorbitol, propylene glycol, poloxamer 407, hydroxyethyl cellulose, sodium benzoate, methylparaben, propylparaben, sodium phosphate and disodium phosphate) using a microbrush (Kerr Corporation, Orange, CA, USA) and then dried completely for approximately 20 s using an air syringe.

2.3.2. Phosphoric Acid Etching

The specimen was etched in a 35% phosphoric acid solution (Ultradent Inc., South Jordan, UT, USA) for a duration of 30 s [17]. It underwent a water-cleaning process followed by a fifteen-second drying period using a triple-syringe spray.

2.3.3. Morpholine Treatment

To prepare a 9.8% morpholine solution (medical-grade morpholine, Loba Chemie PVT Ltd., Mumbai, India), 98% morpholine was diluted with distilled water, increasing the volume from 10 mL to 100 mL. A single-use microbrush was used to thinly apply 10 microliters of the 9.8% morpholine solution to the surface. The coated surface was carefully dried for 20 s using air supplied by a triple syringe [16,17].

2.3.4. Adhesive Agent Treatment

A microbrush scrubbed the adhesive onto the specimen’s surface for 20 s, and a new microbrush was used to remove any leftover adhesive. The adhesive’s solvent was eliminated by a gentle air-drying process lasting about fifteen seconds. Air drying was permitted until the surface achieved a glossy appearance and stopped exhibiting any further liquid motion. Following that, it underwent a 20 s light-curing operation.

2.4. Resin Composite Application

An ultradent mold featuring dimensions of 2.0 mm in depth and 2.0 mm in diameter was positioned on the upper surface of the treated specimen. The resin composite (Harmonize, Kerr Corporation, Orange, CA, USA) was pushed into an ultradent mold, and a light-curing operation was performed on the top of an ultradent mold for 40 s. An ultradent mold was removed and then subjected to light polymerization for 40 s once more (Figure 2). Every sample was submitted to a single-day incubation process (Bio Laboratories Pte Ltd., Ubi Techpark, Singapore) supplied with distilled water at a temperature of 37 degrees Celsius.

2.5. Shear Bond Strength (SBS) Test and Fracture Pattern Investigation

The SBS values were computed using a universal measuring platform (AGS-X 500N, Shimadzu Corporation, Kyoto, Japan) at a test speed of 0.5 mm/min (Figure 3). To calculate the SBS value, the adhesion area and the bond breakdown strength were divided.
The fracture mechanism patterns of RBC-CAD/CAM and resin composites were observed with a stereomicroscope at ×50 magnification. Three distinct designs were introduced to identify the fracture mechanisms [21,22,23]:
(A)
An adhesive design refers to the failure that occurs at the contact between RBC-CAD/CAM and resin composites.
(B)
A cohesive design is one which features fractures in RBC-CAD/CAM or resin composites.
(C)
A mixed design includes both adhesive and cohesive failure designs.

2.6. Data Analysis

The statistical data were analyzed using a one-way analysis of variance (ANOVA), with an acceptable level of significance of p < 0.05 determined based on Tukey’s test.

3. Results

Figure 4 represents the mean SBS values with standard deviation (SD). The groups with the highest SBS values were groups 2, 4, and 5, with values of 21.43 ± 1.93, 20.93 ± 1.46, and 22.02 ± 1.77 MPa, respectively. However, these values were not statistically different from each other (p > 0.05). Group 1 had the lowest SBS value by a significant amount (1.88 ± 1.01 MPa). The bond strength values of group 3 (10.73 ± 1.21 MPa) were significantly different compared to those of groups 1, 2, 4, and 5 (p < 0.05).
A brief description of the failure mode distribution design is shown in Table 3. Following their fracture, all specimens in group 1 were determined to have had adhesive failures. Furthermore, failure types characterized by mixed and cohesive failures were seen in groups 2 to 5. Group 5 had the greatest proportion of cohesive failures, reaching 80%.
In the part of the stereomicroscope assessment, the stereomicroscope pictures of examples of the failure modes in groups 1 to 5 (adhesive, mixed, and cohesive fracture modes) are represented in Figure 5, Figure 6, Figure 7, Figure 8 and Figure 9. Group 1 exhibited the greatest percentage of adhesive failures (Figure 5). Group 3 demonstrated 90 percent adhesive failures and 10 percent mixed failures (Figure 7). Meanwhile, groups 2, 4, and 5 presented a high percentage of cohesive failures (Figure 6, Figure 8, and Figure 9).

4. Discussion

The purpose of this research is to evaluate how morpholine affects saliva-contaminated RBC-CAD/CAM material that has been repaired with a resin composite. The null hypothesis suggests that using morpholine does not significantly enhance the bond strength between saliva-contaminated RBC-CAD/CAM material and resin composite. The findings reveal considerable differences in the SBS values between group 5 and groups 1 and 3. Therefore, we deny the null hypothesis.
Micro-mechanical bonding and chemical bonding are two important processes that work synergistically in repair procedures, especially in dentistry and materials science, to ensure the effective adhesion and durability of the repair [12,13,24]. Micro-mechanical bonding refers to the physical interlocking of materials at a microscopic level. Typically, we apply the repair material to a roughened and irregular surface, such as a dental filling or a broken piece of material, to create a mechanical interlock that helps hold the material in place. This bonding mechanism relies purely on the physical structure and surface texture of the material and does not involve chemical reactions. Chemical bonding, in addition to the physical interlock, involves the formation of molecular interactions between the repair material and the substrate. Primers and adhesive agents often improve adhesion between materials by creating covalent or ionic bonds, thereby promoting a stronger and more durable bond [12,13,16,17,24].
The protocol for surface treatment in RBC-CAD/CAM material involves micro-mechanical retention. The sandblast method is recommended for the RBC-CAD/CAM material [12,13,24]. According to Limsiriwong et al. and Fouquet et al., the bond strength values of RBC-CAD/CAM materials were improved by the sandblasting process as compared to the non-sandblasted surface [12,25]. Additional advantages of sandblasted material include cleaning the bonding region after saliva contamination by displaying a completely clean surface [26]. To increase the chemical interaction between the RBC-CAD/CAM materials and resin composite, it is recommended to treat the surface of the RBC-CAD/CAM materials using a primer, silane, or adhesive agent [13,24]. These two bonding methods often cooperate during a repair procedure to increase the successful outcome of the repair for RBC-CAD/CAM material.
The study results suggest that saliva contamination significantly reduces the SBS of dental adhesives. Specifically, groups 1 and 3, which were exposed to saliva contamination, demonstrated significantly lower bond strengths (1.88 ± 1.01 MPa and 10.73 ± 1.21 MPa, respectively), compared to group 2, which was not contaminated by saliva and showed a much higher SBS (21.43 ± 1.93 MPa). Saliva may influence the bonding strength of restorative materials, possibly resulting in inadequate bonding capacity and longevity [14,16,17,27,28]. On the contrary, Pinzon et al. reported that the salivary mucins do not significantly impair the bonding ability of dental adhesives [29]. The effect of salivary mucin on bond strength varies depending on the type of adhesive system and the decontamination method used [29]. The study by Bolme et al. highlights an important issue of saliva contamination in restorative dentistry: simply decontaminating saliva with water and air spray may not enhance the bond strength. This result indicates that the removal of saliva through water and air spray may not be sufficient to restore the optimal bonding conditions needed for successful adhesion [15]. Strong adhesive bonding is directly dependent on two main factors: a clean surface and a high-energy surface. The surface must be free from contaminants to ensure proper bonding, and it must have a high surface energy to allow the adhesive to spread and interact effectively. The recommendation by Yin et al. that phosphoric acid etching may be useful to eliminate oral substances such as saliva and gingival fluid from the surface of restorative materials is an interesting aspect of dental bonding and surface preparation [30]. The acidic solution can partially break down the mucins and proteins found in these fluids, making it easier for the adhesive to penetrate the surface. The acid removes not only the smear layer but also any potential contaminants on the material’s surface that can bond more effectively with the adhesive. Consequently, 30 s of phosphoric acid etching is applied for saliva decontamination, providing a positive control in group 4 (saliva + PHR + SCP), which exhibited the statistically strongest SBS values (20.93 ± 1.46 MPa).
Saliva contamination data showed that group 4 (saliva + PHR + SCP) and group 5 (saliva + MRL + SCP) had the significantly highest significant SBS values. The results indicate that saliva contamination does not always drastically reduce bond strength, especially when certain treatments with morpholine or phosphoric acid are used before the adhesive agent. The morpholine treatment could be specifically designed to improve bonding performance even in the presence of contaminants with saliva [16,17]. This could be achieved through a mechanical or chemical process that enhances the interaction between the RBC-CAD/CAM material surface and the adhesive agent, leading to the highest bond strength observed in this particular group. Morpholine is a heterocyclic organic compound commonly used in various chemical and industrial applications, including as a cleaning agent, solvent, or additive in certain formulations [19]. Using morpholine as part of the surface preparation protocol in restorative dentistry could offer several advantages, such as effective cleaning, elimination of debris, and the promotion of higher surface energy, all of which are critical for achieving strong adhesive bonds [16,17,20]. The solvent properties of morpholine could aid in the effective removal of any remaining debris or contaminants. Moreover, morpholine, being a solvent, has the potential to partially dissolve or swell the resin matrix. Swelling occurs when solvent molecules penetrate the polymer network, causing the resin matrix to expand. When the resin matrix expands, the adhesive agent’s monomer can penetrate into the matrix, potentially leading to a high bond strength [16,17]. Ghosh et al. reported using morpholine as an initiator in the polymerization of methacrylate. An initiator is a chemical that initiates the polymerization process, usually by cleaving a bond to generate a free radical that can interact with the monomer to produce a polymer chain, which may enhance the polymerization process [31]. This could have practical implications, suggesting that if saliva contamination is unavoidable, alternative bonding protocols or treatments, such as morpholine, may help enhance the bond strength of the RBC-CAD/CAM material.
In this study, the researchers observed different failure modes in several groups of specimens, with adhesive failure being the dominant mode in group 1. However, in groups 2 through 5, the failure modes shifted more towards mixed and cohesive failures. The study found that cohesive failures were more prevalent in groups 2, 4, and 5, particularly in cases where higher bond strength was present. Bond strength refers to the force required to break the bond between two materials; a higher bond strength indicates a stronger bond. The data showed a clear relationship: as the bond strength increased, the number of cohesive failures also increased. This suggests that stronger bonds are more likely to result in cohesive failure [13,24,32,33]. Furthermore, the study highlighted that when the bond strength of a material is closer to its cohesive fracture strength, the repair process is more likely to be successful [34,35]. Thus, optimizing the repair bond strength to match at least 20 MPa is crucial for effective and long-lasting repairs [36,37,38].
The in vitro research study’s design was limited, since it could not be applied to other resin-matrix ceramics due to its focus on one specific Shofu block HC. Only the samples that were kept for 24 h after bonding could measure the SBS of the RBC-CAD/CAM and resin composite, but we could not evaluate the long-term durability. This study determined the SBS, but it did not conduct the other adhesion parameters, such as the micro-tensile test. In further studies, we will compare new materials, such as nitrogen-containing materials [39], with RBC-CAD/CAM. We could potentially use thermocycling to evaluate the long-term durability of repairs using resin composites and RBC-CAD/CAM materials. The efficacy of an adhesion method in a clinical context is contingent upon many parameters, including the SBS. It is important to meticulously analyze the results of our inquiry accordingly.

5. Conclusions

Within the limitations of this study, the current in vitro investigation demonstrated that both morpholine and phosphoric acid effectively enhance bond strength, particularly in situations involving saliva contamination of RBC-CAD/CAM materials. These findings suggest that alternative surface modification strategies, especially the use of morpholine, can significantly improve bonding outcomes under compromised clinical conditions. Clinicians may consider incorporating morpholine-based protocols into their adhesive procedures, particularly when dealing with saliva-contaminated surfaces. However, further in vivo studies are necessary to validate these results and determine long-term clinical performance.

Author Contributions

Conceptualization, A.K., N.K. and N.T.; methodology, A.K., T.S., N.K. and N.T.; formal analysis, A.K., T.S. and N.K.; investigation, A.K. and T.S.; data curation, A.K., T.S., N.K. and N.T.; writing—original draft preparation, A.K., T.S., N.K. and N.T.; writing—review and editing, A.K. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by the Thammasat University Research Fund of Thammasat University, Thailand, Contract No. TUFT 0040/2568.

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. The RBC-CAD/CAM material is placed in a PVC tube filled with epoxy resin.
Figure 1. The RBC-CAD/CAM material is placed in a PVC tube filled with epoxy resin.
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Figure 2. The bonded specimen.
Figure 2. The bonded specimen.
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Figure 3. The SBS test configuration.
Figure 3. The SBS test configuration.
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Figure 4. The mean SBS values with standard deviation, where SCP—Scotchbond universal plus; PHR—phosphoric acid; MRL—morpholine. A value with the same letters does not differ by a statistically significant amount.
Figure 4. The mean SBS values with standard deviation, where SCP—Scotchbond universal plus; PHR—phosphoric acid; MRL—morpholine. A value with the same letters does not differ by a statistically significant amount.
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Figure 5. The stereomicroscope image of adhesive failures of group 1 (AD—adhesive failure).
Figure 5. The stereomicroscope image of adhesive failures of group 1 (AD—adhesive failure).
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Figure 6. The stereomicroscope images of group 2: (A) adhesive failure; (B) mixed failure; (C) cohesive failure (AD—adhesive failure; CO—cohesive failure in RBCs).
Figure 6. The stereomicroscope images of group 2: (A) adhesive failure; (B) mixed failure; (C) cohesive failure (AD—adhesive failure; CO—cohesive failure in RBCs).
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Figure 7. The stereomicroscope images of group 3: (A) adhesive failure; (B) mixed failure (AD—adhesive failure; CO—cohesive failure in RBCs).
Figure 7. The stereomicroscope images of group 3: (A) adhesive failure; (B) mixed failure (AD—adhesive failure; CO—cohesive failure in RBCs).
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Figure 8. The stereomicroscope images of group 4: (A) adhesive failure; (B) mixed failure; (C) cohesive failure (AD—adhesive failure; CO—cohesive failure in RBCs).
Figure 8. The stereomicroscope images of group 4: (A) adhesive failure; (B) mixed failure; (C) cohesive failure (AD—adhesive failure; CO—cohesive failure in RBCs).
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Figure 9. The stereomicroscope images of group 5; (A) adhesive failure; (B) mixed failure; (C) cohesive failure (AD—adhesive failure; CO—cohesive failure in RBCs).
Figure 9. The stereomicroscope images of group 5; (A) adhesive failure; (B) mixed failure; (C) cohesive failure (AD—adhesive failure; CO—cohesive failure in RBCs).
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Table 1. Enumerates the materials used in the present study.
Table 1. Enumerates the materials used in the present study.
MaterialChemical Composition
Resin-based composites CAD/CAM; Shofu Inc., Kyoto, Japan.TEGDMA, UDMA, Filler; Silica powder, micro fumed silica, zirconium silicate, 61% by weight.
Scotchbond universal plus; 3M, Neuss, Germany.HEMA, 2-propenoic acid, 2-methyl-, diesters with 4,6-dibromo-1,3-benzenediol 2-(2-hydroxyethoxy)ethyl 3-hydroxypropyl diethers, 2-propenoic acid, 2-methyl-, reaction products with 1,10-decanediol and phosphorus oxide, 2-propenoic acid, 2-methyl-, 3(triethoxysilyl)propyl

ester, reaction products with silica and 3(triethoxysilyl)-1-propanamine, synthetic amorphous silica, fumed, crystalline-free, ethanol, water, (3-aminopropyl)triethoxysilane, camphorquinone, N,N-dimethylbenzocaine, methacrylic acid, Acetic acid, copper(2+) salt, monohydrate
Morpholine; Loba Chemie PVT Ltd., Mumbai, India.98% Extra-pure O(CH2CH2)2NH
Resin composite, Harmonize A4D; Kerr Corporation, CA, USA.TEGDMA, Bis-GMA, EBPADMA, zirconia/silica cluster filler (2–3 m) comprising 20 nm spherical fumed silica and 5 nm zirconia particles, prepolymerized filler.
Abbreviations: TEGDMA—triethylene glycol dimethacrylate; UDMA—urethane dimethacrylate; HEMA—2-hydroxyethyl methacrylate; Bis-GMA—bisphenol A-glycidyl methacrylate; EBPADMA—Ethoxylated bisphenol A dimethacrylate.
Table 2. Displays the categories of specimens that received surface treatment.
Table 2. Displays the categories of specimens that received surface treatment.
GroupsSurface Modification
1Saliva-contaminated RBCs (saliva)
2Treated with SCP (SCP)
3Saliva-contaminated RBCs treated with SCP (saliva + SCP)
4Saliva-contaminated RBCs treated with phosphoric acid prior to application of SCP (saliva + PHR + SCP)
5Saliva-contaminated RBCs treated with morpholine prior to application of SCP (Saliva + MRL + SCP)
Abbreviations: RBCs—resin-based composite CAD/CAM material; SCP—Scotchbond universal plus; PHR—phosphoric acid; MRL—morpholine.
Table 3. The failure pattern mode (%).
Table 3. The failure pattern mode (%).
GroupsFailure Pattern Mode (%)
AdhesiveMixedCohesive
1. Saliva10000
2. SCP102070
3. Saliva + SCP90100
4. Saliva + PHR + SCP201070
5. Saliva + MRL + SCP101080
Abbreviations: SCP—Scotchbond universal plus; PHR—phosphoric acid; MRL—morpholine.
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MDPI and ACS Style

Klaisiri, A.; Sriamporn, T.; Krajangta, N.; Thamrongananskul, N. Morpholine’s Effects on the Repair Strength of a Saliva-Contaminated CAD/CAM Resin-Based Composite Mended with Resin Composite. J. Compos. Sci. 2025, 9, 345. https://doi.org/10.3390/jcs9070345

AMA Style

Klaisiri A, Sriamporn T, Krajangta N, Thamrongananskul N. Morpholine’s Effects on the Repair Strength of a Saliva-Contaminated CAD/CAM Resin-Based Composite Mended with Resin Composite. Journal of Composites Science. 2025; 9(7):345. https://doi.org/10.3390/jcs9070345

Chicago/Turabian Style

Klaisiri, Awiruth, Tool Sriamporn, Nantawan Krajangta, and Niyom Thamrongananskul. 2025. "Morpholine’s Effects on the Repair Strength of a Saliva-Contaminated CAD/CAM Resin-Based Composite Mended with Resin Composite" Journal of Composites Science 9, no. 7: 345. https://doi.org/10.3390/jcs9070345

APA Style

Klaisiri, A., Sriamporn, T., Krajangta, N., & Thamrongananskul, N. (2025). Morpholine’s Effects on the Repair Strength of a Saliva-Contaminated CAD/CAM Resin-Based Composite Mended with Resin Composite. Journal of Composites Science, 9(7), 345. https://doi.org/10.3390/jcs9070345

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