Abstract
Background:
Composites with 0.2% chitosan nanoparticles (CSN) are used recently; however, this combination needs to be studied in different cavity designs.
Aims:
The aim of the study was to compare the fracture resistance of maxillary premolars with different cavity geometries restored with different types of composite resins incorporated with 0.2% CSN.
Methods:
About 130 extracted human single-rooted maxillary premolars were embedded in acrylic molds 2 mm below cementoenamel junction, divided into five groups for cavity preparations of standardized dimensions. Group 1: (control) intact teeth (n = 10), Group 2: Class I cavities (n = 40), Group 3: Class II mesio-occlusal (MO) (n = 40), Group 4: Class II mesio-occluso-distal (MOD) (n = 40). Groups 2, 3, and 4 were subdivided into four subgroups for composite restoration; A: Neo spectra ST-Universal (NST); B: Tetric N-Ceram Bulk-fill (TNC); C: NST + CSN; and D: TNC + CSN and tested for fracture resistance using universal testing machine.
Statistical Analysis:
One-way analysis of variance and post hoc Tukey’s tests were used for data analysis (P ≤ 0.05).
Results:
In all groups, the highest fracture resistance was found in MOD cavities, followed by MO and least in Class I cavities. Subgroup D (TNC with CSN) showed the highest fracture resistance in all groups (P ≤ 0.05).
Conclusion:
Tetric N-Ceramic bulk fill with 0.25% CSN showed high fracture resistance in cavities with different geometries.
Keywords: Bulk-fill composite, chitosan nanoparticles, fracture resistance, universal composite
INTRODUCTION
Composite resins are the most widely used restorative materials in dentistry mainly for esthetic reasons. Over the years, improvements in composite materials and techniques including bonding systems were seen with longevity and direct filling capabilities in posterior restorations.[1]
Universal resin composites were developed for easy adaption to cavity walls, margins, and surfaces in both direct and indirect restorations.[2] Neo spectra ST (NST) (Dentsply, Konstans, Germany) is a nanoceramic-based universal composite resin that has been developed based on superior composite technology known as Sphere technology (SphereTEC) consisting of granulated spherical fillers of different sizes along with optimized resin matrix. Their morphology, particle size distribution, and surface microstructure deliver the benefits of easy handling, nonsticky in nature with adequate adaptation, easy condensation, that is available in both high and low viscosities. Shade selection is simple with five universal shades that match all teeth with excellent esthetics and can be used for both direct and indirect restorations.[3,4]
Bulk-fill composites were designed for placement of resin composite in a bulk, thus reducing the technique sensitivity and chair side time,[5] Tetric N-Ceram (TNC) Bulk fill (Ivoclar Vivadent, Schann, Liechtenstein) is a nanohybrid bulk-fill composite. It contains glycol dimethacrylate monomer resin matrix – 21%, fillers made up of barium, ytterbium fluoride, and trioxides – 61%, 17% of polymer filler, and 1 wt. % of initiators, stabilizers, and pigments. It exhibits less polymerization shrinkage with higher polymerization depth and allows for placement in a single increment of about 4 mm. Hence suitable for posterior direct restorations which pose technical challenges during placement.[6,7]
Posterior composite restorations pose difficulty due to technique sensitivity, accessibility, isolation, and the cavities of different geometries in posterior areas such as Class I, Class II, and mesio-occluso-distal (MOD) cavities are subjected to several types of stresses and masticatory load.[8]
Extensive studies were done for improving the esthetics and properties of composite resins. Antibacterial composite resins were synthesized by employing antibacterial agents such as methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB) and cetylpyridinium chloride.[9]
Studies suggest that chitosan nanoparticles (CSN) incorporated in composite resins or dental adhesives exhibited improved antibacterial property, without affecting the bond strength.[3,10] However, the combination of composites with CSN might affect the strength of the tooth, since the addition of any other substance or material to existing material might affect its properties such as the compressive/tensile strength and bond strength, since different types of composites such as Bulk Fill and universal composites that are recommended for restoration in posterior region; hence, it is essential to evaluate the effect of addition of CSN to these composites. Till now, no studies were reported regarding the fracture resistance of maxillary premolar teeth with different types of cavity designs restored with different composites incorporated with CSN; hence, this study was undertaken.
METHODS
Approval from the ethical committee of the institute was obtained for this study (Ref no-IEC/2020-2021/S-17) and conducted accordingly.
Hundred and thirty freshly extracted human maxillary premolar teeth for orthodontic purpose were collected and cleaned using ultrasonic scalers (Woodpecker Piezo scaler USD-J, China) to remove soft-tissue debris and stains, followed by storage in distilled water until further use. The specimens were encased in acrylic resin blocks 2 mm below the cementoenamel junction (CEJ) and were divided into four groups:
Group 1: (control) Intact teeth (n = 10)
Group 2: Class I cavity (n = 40)
Group 3: Class II mesio-occlusal cavity (MO) (n = 40)
Group 4: Class II MOD cavity (n = 40).
Further four subgroups were done in the Groups 2–4 for composite restorations as:
Subgroup A: NST Universal composite
Subgroup B: TNC Bulk-fill composite
Subgroup C: NST Universal composite + 0.2% CSN (NST + CSN) (1:1 ratio)
Subgroup D: TNC Bulk-fill composite + 0.2% CSN (TNC + CSN) (1:1 ratio).
About 0.05 g CSN powder particles (SRL Pvt Ltd, Hyderabad, India) were dispersed in 23 ml of distilled water with 0.05 ml of acetic acid (Sigma laboratories, Mumbai, India) and mixed properly for obtaining 0.25% CSN solution. One milliliter of 0.06gms of tripolyphosphate solution (Sigma laboratories, Mumbai, India) was then added, and the mixture was allowed to stand for 24 h.[11,12] Freshly prepared 0.1 ml CSN solution was further added to 0.01 g of Neo spectra and TNC bulk-fill composites in 1:1 ratio separately in a glass beaker and mixed with a glass stirrer in the dark room and left for 24 h.
In Group 2, Class I cavities of standard dimensions of mesiodistal length of 4 mm, buccopalatal width of 3 mm, and pulpal depth 3 mm were prepared with a cylindrical diamond bur (Mani, Hyderabad, India) under high-speed air water-cooled handpiece (Drillerz-EM, Hyderabad, India).[13]
In Group 3, (Class II MO cavities) and Group 4 (Class II MOD cavities) were prepared with a 2 mm pulpal depth using straight bur (Mani, Hyderabad, India), and 2 mm cavity buccolingual width was prepared using inverted bur. Gingival floor was prepared 1 mm below the CEJ using a no -010 straight fissured diamond bur under a high-speed air water-cooled handpiece.[3]
In all the groups, G-Premio Bond (GC Dental Products Corp, Kasugai, Japan) adhesive was applied and left undisturbed for 10 s, then air-dried and light-cured for 20 s using LED curing unit (Woodpecker, Muenster, Germany), followed by placement of Palodent V3 sectional matrix system (Dentsply Sirona, USA) in Groups 3 and 4 for obtaining the tight contact.
In Subgroups A and C, NST composite resin with and without CSN was placed into the prepared cavities using the incremental technique of l mm thickness and light-cured for 20 s. Whereas, in Subgroups B and D, TNC Bulk-Fill composite with and without CSN were placed into the cavities in 4 mm thickness and light cured for 20 s. In all the groups, finishing and polishing were done with a composite polishing kit (Shofu Dental India Private Limited, India), and specimens were left aside for 24 h.
For the evaluation of fracture resistance, the specimens of each group were loaded vertically under a universal testing machine (Instron JOEL 3352, USA). Fracture resistance was tested using a steel ball of 4 mm diameter with a cross-head speed of 1 mm/min until the specimen fractures and load was recorded in Newtons [Figure 1].
Figure 1.
Determination of fracture resistance of the specimen loaded under universal testing machine
Statistical analysis
The data were subjected to statistical analysis using R Programming software version R 3.2.1 (R core, New Zealand) by one-way analysis of variance (ANOVA) and post hoc Tukey’s tests at a level of significance with P ≤ 0.05.
RESULTS
Analysis by one-way ANOVA showed highest fracture resistance in Subgroup 4D, followed by 4C, 4B, 4A, 3D, 3B, 3C, 3A, 2D, 2B, and least in 2A. Among the groups, fracture resistance was found to be highest in Group 4, followed by Group 3, control group, Group 2, and least in Group 1. In all the groups, Subgroup D showed the highest fracture resistance, followed by Subgroups C and B and least in Subgroup A [Table l].
Table 1.
One-way ANOVA analysis of fracture resistance of all the groups
| Group | Mean | SD |
|---|---|---|
| Group 1 (positive control) | 550.8 | 20.4621 |
| Group 2 (Class I) | ||
| Subgroup A | 214.6 | 30.4269 |
| Subgroup B | 241.2 | 5.2631 |
| Subgroup C | 344.8 | 7.7589 |
| Subgroup D | 396.0 | 12.9422 |
| Group 3 (Class II MO) | ||
| Subgroup A | 463.8 | 12.0706 |
| Subgroup B | 474.8 | 5.8052 |
| Subgroup C | 474.0 | 12.9421 |
| Subgroup D | 571.4 | 10.0648 |
| Group 4 (Class II MOD) | ||
| Subgroup A | 656.6 | 15.0930 |
| Subgroup B | 664.2 | 10.0349 |
| Subgroup C | 720.0 | 35.5317 |
| Subgroup D | 892.4 | 28.6409 |
| P | <0.00001 (S) | |
MO: Mesio-occlusal, MOD: MO distal, S: Significant difference
Multiple comparisons by post hoc Tukey test showed significant difference between all groups except between Group 1 (control) and Subgroup 3D, between Subgroup 2A and 2B, between 3A and 3B, 3C, Group 3B with Group 3C and 4A with Group 4B [Table 2].
Table 2.
Multiple comparison of fracture resistance among all groups by post hoc Tukey test
| Groups | Comparison groups | Difference | P |
|---|---|---|---|
| Group 1 | Subgroup 2A | 336.2 | <0.00001 (S) |
| Subgroup 2B | 309.6 | <0.00001 (S) | |
| Subgroup 2C | 206.0 | <0.00001 (S) | |
| Subgroup 2D | 154.8 | <0.00001 (S) | |
| Subgroup 3A | 87.0 | <0.00001 (S) | |
| Subgroup 3B | 76.0 | <0.00001 (S) | |
| Subgroup 3C | 76.8 | <0.00001 (S) | |
| Subgroup 3D | 20.6 | 0.8901 (NS) | |
| Subgroup 4A | 105.8 | <0.00001 (S) | |
| Subgroup 4B | 113.4 | <0.00001 (S) | |
| Subgroup 4C | 169.2 | <0.00001 (S) | |
| Subgroup 4D | 341.6 | <0.00001 (S) | |
| Subgroup 2A | Subgroup 2B | 26.6 | 0.5674 (NS) |
| Subgroup 2C | 130.2 | <0.00001 (S) | |
| Subgroup 2D | 181.4 | <0.00001 (S) | |
| Subgroup 3A | 249.2 | <0.00001 (S) | |
| Subgroup 3B | 260.2 | <0.00001 (S) | |
| Subgroup 3C | 259.4 | <0.00001 (S) | |
| Subgroup 3D | 356.8 | <0.00001 (S) | |
| Subgroup 4A | 505.4 | <0.00001 (S) | |
| Subgroup 4B | 449.6 | <0.00001 (S) | |
| Subgroup 4C | 505.4 | <0.00001 (S) | |
| Subgroup 4D | 677.8 | <0.00001 (S) | |
| Subgroup 2B | Subgroup 2C | 103.6 | <0.00001 (S) |
| Subgroup 2D | 154.8 | <0.00001 (S) | |
| Subgroup 3A | 222.6 | <0.00001 (S) | |
| Subgroup 3B | 233.6 | <0.00001 (S) | |
| Subgroup 3C | 232.8 | <0.00001 (S) | |
| Subgroup 3D | 330.2 | <0.00001 (S) | |
| Subgroup 4A | 415.4 | <0.00001 (S) | |
| Subgroup 4B | 423.0 | <0.00001 (S) | |
| Subgroup 4C | 478.8 | <0.00001 (S) | |
| Subgroup 4D | 651.2 | <0.00001 (S) | |
| Subgroup 2C | Subgroup 2D | 51.2 | 0.0021 (S) |
| Subgroup 3A | 119.0 | <0.00001 (S) | |
| Subgroup 3B | 130.0 | <0.00001 (S) | |
| Subgroup 3C | 129.2 | <0.00001 (S) | |
| Subgroup 3D | 226.6 | <0.00001 (S) | |
| Subgroup 4A | 311.8 | <0.00001 (S) | |
| Subgroup 4B | 319.4 | <0.00001 (S) | |
| Subgroup 4C | 375.2 | <0.00001 (S) | |
| Subgroup 4D | 547.6 | <0.00001 (S) | |
| Subgroup 2D | Subgroup 3A | 67.8 | <0.00001 (S) |
| Subgroup 3B | 78.8 | <0.00001 (S) | |
| Subgroup 3C | 78.0 | <0.00001 (S) | |
| Subgroup 3D | 175.4 | <0.00001 (S) | |
| Subgroup 4A | 260.6 | <0.00001 (S) | |
| Subgroup 4B | 268.2 | <0.00001 (S) | |
| Subgroup 4C | 324.0 | <0.00001 (S) | |
| Subgroup 4D | 496.4 | <0.00001 (S) | |
| Subgroup 3A | Subgroup 3B | 11.0 | 0.9998 (NS) |
| Subgroup 3C | 10.2 | 0.9999 (NS) | |
| Subgroup 3D | 107.6 | <0.00001 (S) | |
| Subgroup 4A | 192.8 | <0.00001 (S) | |
| Subgroup 4B | 200.4 | <0.00001 (S) | |
| Subgroup 4C | 256.2 | <0.00001 (S) | |
| Subgroup 4D | 4286 | <0.00001 (S) | |
| Subgroup 3B | Subgroup 3C | 0.8 | <0.00001 (S) |
| Subgroup 3D | 96.6 | <0.00001 (S) | |
| Subgroup 4A | 181.8 | <0.00001 (S) | |
| Subgroup 4B | 189.4 | <0.00001 (S) | |
| Subgroup 4C | 245.2 | <0.00001 (S) | |
| Subgroup 4D | 417.6 | <0.00001 (S) | |
| Subgroup 3C | Subgroup 3D | 97.4 | <0.00001 (S) |
| Subgroup 4A | 182.6 | <0.00001 (S) | |
| Subgroup 4B | 190.2 | <0.00001 (S) | |
| Subgroup 4C | 246.0 | <0.00001 (S) | |
| Subgroup 4D | 418.4 | <0.00001 (S) | |
| Subgroup 3D | Subgroup 4A | 85.2 | <0.00001 (S) |
| Subgroup 4B | 92.8 | <0.00001 (S) | |
| Subgroup 4C | 148.6 | <0.00001 (S) | |
| Subgroup 4D | 321.0 | <0.00001 (S) | |
| Subgroup 4A | Subgroup 4B | 7.6 | 0.9999 (NS) |
| Subgroup 4C | 63.4 | <0.00001 (S) | |
| Subgroup 4D | 677.8 | <0.00001 (S) | |
| Subgroup 4B | Subgroup 4C | 55.8 | <0.00001 (S) |
| Subgroup 4D | 228.2 | <0.00001 (S) | |
| Subgroup 4C | Subgroup 4D | 172.4 | <0.00001 (S) |
S: Significant difference, NS: No significant difference
DISCUSSION
Fracture of restoration in a tooth can be explained as an incomplete or complete break in the material itself or along with the tooth structure that often results from excessive occlusal forces. The cavity preparation significantly increases the weakness of the remaining tooth structure. Restored teeth have some cuspal deflection due to excess forces acting on them which results in fracture/crack of the material or the tooth structure.[14]
One of the advantages of direct composite restorations is the preservance of the remaining tooth structure.[15] However, the drawbacks of composite restorations are the limited life span, secondary caries, and polymerization shrinkage. During the curing phase, composite resins undergo contraction of material, and its flow decreases as the hardness increases which depends on the type of composite resin used and the cavity geometry, hence resulting in increased stress distribution which leads to bond failure.[16] To overcome these drawbacks, some newer materials such as CSN were added with composites to improve its properties such as antimicrobial activity and pushout bond strength.[3,17]
In the present study, the highest fracture resistance was found with Tetric N Ceram Bulk Fill compared to NST universal composite resin. Agarwal et al. stated that the viscosity of the bulk-fill composite material influences the amount of marginal interface and its quality of adaptation to the inner walls.[12] The present study is in line with the above study and with Kale et al.[14] and Bilgi et al.,[15] with the highest fracture resistance of TNC bulk-fill composite resin.
França et al., in a study, evaluated fracture strength, microtensile bond strength, and microhardness of low- and high-viscosity bulk-fill composite restorations and stated that high-viscosity TNC bulk-fill composite resin exhibited higher KHN values at the increment of 4 mm than at 2 mm. The high-viscosity composites contain higher amount of fillers and are indicated in cavities prone to greater fracture or wear.[16]
The bonding effectiveness of composite restorative materials is affected by different techniques of composite placement. Considering this fact, the study findings are in accordance with Al-Harbi et al. stated that bulk-fill composite restorations provided better cervical interfacial quality than incremental fill restorations of Class Il cavities along with increased microtensile bond strength.[17] In the present study, the highest fracture resistance in Tetric N-Ceram Bulk Fill can be attributed to its composition to the fact that the substitution of BisGMA and TEGDMA by UDMA that lowered solubility and water sorption, hence increased the mechanical properties due to the increased degree of conversion. The inorganic filler particle size that ranges between 0.1 μm and 30 μm with a mean particle size of 5 μm and low elastic modulus which acts as a shrinkage stress reliever. It also contains a new light initiator known as Ivocerin, which can absorb blue light wavelengths ranging from 370 to 460 nm. This is more reactive toward light compared to camphorquinone, thus allowing for quick polymerization with deeper curing depth. This resin composite has a compressive strength of 224 MPa.[18] On the other hand, Neo Spectra ST consists of organically modified ceramic organic matrix consisting of methacrylate-modified polysiloxane, dimethacrylate resins, ethyl-4 (dimethylamino) benzoate, and bis (4-methyl-phenyl) iodonium hexafluorophosphate. Fillers of about 78%–80% by weight that are spherical in shape, nonagglomerated, prepolymerized barium glass, and ytterbium fluoride SphereTEC fillers of particle size 50 ≈ 15 μm. Vickers microhardness (VHN) value of this resin is 62.69 VHN.[6] According to Farahanny et al., bulk-fill composite resins exhibit the highest fracture resistance in Class I cavities of endodontically treated teeth.[19]
The different cavity geometries of Class I, Class II MO, and MOD cavities are also the factors that influence fracture resistance, since the C-factor in different cavity preparations are different from each other, the highest C-factor in Class I cavities influences the fracture resistance than in Class II and Class II MOD cavities.[20] de la Macorra and Gomez-Fernandez measured the configuration factor value for Class I and Il cavities and simulated cervical erosions in molar tooth and showed that configuration (C-factor) was highest with Class I cavities followed by Class II MO and least in MOD cavities.[21] Hence, in accordance with the above studies, the highest fracture resistance was found in MOD cavities, followed by MO and least in Class I cavities with the highest C factor. The present study results are in accordance with Atiyah and Baban reported that MOD cavities restored with SDR (smart dentine replacement) bulk-fill material showed higher fracture resistance compared to packable composite resin.[22] This could be attributed to unique filler composition, highly cross-linked resin matrix, and resiliency of bulk-fill composites which helps to withstand higher stress before fracture.
Mohamed et al. assessed microtensile bond strength of CSN incorporated in composite resin with self-etch adhesive of aged restorations. Dentin was pretreated with 0.2% and 2.5% CSN and results showed the addition of CSN had shown to increase the bond strength even after 6 months aging.[23] In the present study, the addition of CSN has shown to improve the fracture resistance for both the composites. Botelho et al., in a study, evaluated microtensile bond strength of CSN incorporated self-etch adhesive system before and after artificial aging and stated that CSN promoted bond strength over time when incorporated with adhesive systems due to the formation of calcium phosphate layer on dentin.[24] Halkai et al. evaluated the pushout bond strength of CSN incorporated in self-etch dentin bonding agents and composites in Class II cavities in maxillary molars and reported that lower bond strength was found in CSN incorporated adhesives compared to CSN incorporated composites, this might be due to difference in materials used and aging periods.[3]
The clinical significance of the present study is to evaluate the effect of the addition of CSN to different composite resins restored in cavities of different geometries, thus providing information regarding the suitability of material for clinical success. Therefore, within the limitations of the present study, the highest fracture resistance was found with CSN-incorporated Tetric-N-Ceram Bulk-Fill composite resin. However, the limitations of the present study are it is an in vitro study, type of composite materials, and the bonding agent used might alter the results; therefore, further studies and clinical long-term research studies are needed.
CONCLUSION
TNC Bulk-Fill composite resin incorporated with 0.25% CSN showed the highest fracture resistance in cavities with different geometries.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
REFERENCES
- 1.Ravi RK, Alla RK, Shammas M, Devarhubli A. Dental composites-a versatile restorative material: An overview. Indian J Dent Sci. 2013;5:2231–93. [Google Scholar]
- 2.Bompolaki D, Lubisich EB, Fugolin AP. Resin-based composites for direct and indirect restorations: Clinical applications, recent advances, and future trends. Dent Clin North Am. 2022;66:517–36. doi: 10.1016/j.cden.2022.05.003. [DOI] [PubMed] [Google Scholar]
- 3.Halkai RS, Gopinagaruri SP, Halkai KR, Hussain A, Rangappa J, Reshma SF. Evaluation of push-out bond strength of different concentrations of chitosan nanoparticles incorporated composite resin and eighth-generation bonding agent for class II restoration: An in vitro study. J Conserv Dent. 2022;25:666–71. doi: 10.4103/jcd.jcd_336_22. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Almutairi MA, Salama FS, Alzeghaibi LY, Albalawi SW, Alhawsawi BZ. Surface treatments on repair bond strength of aged resin composites. J Int Soc Prev Community Dent. 2022;12:449–55. doi: 10.4103/jispcd.JISPCD_99_22. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Xue J. Factors influencing clinical application of bulk-fill composite resin. Hua Xi Kou Qiang Yi Xue Za Zhi. 2020;38:233–9. doi: 10.7518/hxkq.2020.03.001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Gurgan S, Koc Vural U, Miletic I. Comparison of mechanical and optical properties of a newly marketed universal composite resin with contemporary universal composite resins: An in vitro study. Microsc Res Tech. 2022;85:1171–9. doi: 10.1002/jemt.23985. [DOI] [PubMed] [Google Scholar]
- 7.El-Damanhoury H, Platt J. Polymerization shrinkage stress kinetics and related properties of bulk-fill resin composites. Oper Dent. 2014;39:374–82. doi: 10.2341/13-017-L. [DOI] [PubMed] [Google Scholar]
- 8.Jasse FF, de Melo Alencar C, Pollo NF, Silva CM, de Campos EA. Molars fracture resistance with class II cavities restored with different resin-based materials. J Health Sci. 2021;23:25–9. [Google Scholar]
- 9.Xiao YH, Ma S, Chen JH, Chai ZG, Li F, Wang YJ. Antibacterial activity and bonding ability of an adhesive incorporating an antibacterial monomer DMAE-CB. J Biomed Mater Res B Appl Biomater. 2009;90:813–7. doi: 10.1002/jbm.b.31350. [DOI] [PubMed] [Google Scholar]
- 10.Tanaka CB, Lopes DP, Kikuchi LN, Moreira MS, Catalani LH, Braga RR, et al. Development of novel dental restorative composites with dibasic calcium phosphate loaded chitosan fillers. Dent Mater. 2020;36:551–9. doi: 10.1016/j.dental.2020.02.004. [DOI] [PubMed] [Google Scholar]
- 11.Swethavinayagam KE, Venkatesan D, Rebecca LJ. Preparation of chitosan nanoparticles and its synergistic effects against gram positive and gram-negative microorganisms. J Pure Appl Microbiol. 2019;13:2317–24. [Google Scholar]
- 12.Agarwal M, Agarwal MK, Shrivastav N, Pandey S, Das R, Gaur P. Preparation of chitosan nanoparticles and their in-vitro characterization. Int J Life Sci Res. 2018;4:1713–20. [Google Scholar]
- 13.Kartikasari AD, Indrawati D, Kamizer Comparative study of resin composite class I restoration microleakage between bulk fill technique with and without sonic activation, and incremental technique. J Phys Conf Ser. 2017;884:012063. [Google Scholar]
- 14.Kale AR, Singh S, Podar R, Kumar M, Chandrasekhar P, Kulkarni G. An in vitro investigation on the reinforcing potential of contemporary composites in weakened bicuspids. J Conserv Dent. 2021;24:589–93. doi: 10.4103/jcd.jcd_279_21. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Bilgi PS, Shah NC, Patel PP, Vaid DS. Comparison of fracture resistance of endodontically treated teeth restored with nanohybrid, silorane, and fiber reinforced composite: An in vitro study. J Conserv Dent. 2016;19:364–7. doi: 10.4103/0972-0707.186458. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.França FM, Tenuti JG, Broglio IP, Paiva LE, Basting RT, Turssi CP, et al. Low- and high-viscosity bulk-fill resin composites: A comparison of microhardness, microtensile bond strength, and fracture strength in restored molars. Acta Odontol Latinoam. 2021;34:173–82. doi: 10.54589/aol.34/2/173. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Al-Harbi F, Kaisarly D, Michna A, ArRejaie A, Bader D, El Gezawi M. Cervical interfacial bonding effectiveness of class II bulk versus incremental fill resin composite restorations. Oper Dent. 2015;40:622–35. doi: 10.2341/14-152-L. [DOI] [PubMed] [Google Scholar]
- 18.Dionysopoulos D. Bulk fill composite resins. A novelty in resin-based restorative materials. ARC J Dent Sci. 2016;1:1–3. [Google Scholar]
- 19.Farahanny W, Dennis, Aruldas MD. Fracture resistance of various bulk fill composite resin in endodontically treated class I premolar (an in-vitro study) J Evol Med Dent Sci. 2017;6:5168–71. [Google Scholar]
- 20.El-Sahn NA, El-Kassas DW, El-Damanhoury HM, Fahmy OM, Gomaa H, Platt JA. Effect of C-factor on microtensile bond strengths of low-shrinkage composites. Oper Dent. 2011;36:281–92. doi: 10.2341/10-105-L. [DOI] [PubMed] [Google Scholar]
- 21.de la Macorra JC, Gomez-Fernandez S. Quantification of the configuration factor in class I and II cavities and simulated cervical erosions. Eur J Prosthodont Restor Dent. 1996;4:29–33. [PubMed] [Google Scholar]
- 22.Atiyah AH, Baban LM. Fracture resistance of endodontically treated premolars with extensive MOD cavities restored with different composite restorations. J Baghdad Coll Dent. 2014;26:7–15. [Google Scholar]
- 23.Mohamed AM, Nabih SM, Wakwak MA. Effect of chitosan nanoparticles on microtensile bond strength of resin composite to dentin: An in vitro study. Braz Dent. 2020;23:1–10. [Google Scholar]
- 24.Botelho LP, Dias De Oliveira SG, Douglas De Oliveira DW, Galo R. Microtensile resistance of an adhesive system modified with chitosan nanoparticles. J Conserv Dent. 2022;25:278–82. doi: 10.4103/jcd.jcd_612_21. [DOI] [PMC free article] [PubMed] [Google Scholar]