Indian Journal of Dental Sciences

: 2023  |  Volume : 15  |  Issue : 1  |  Page : 33--36

Push-out bond strength of alkasite restorative material and bulk-fill composite used with universal adhesive system: An in vitro study

Nikita Goyal1, Poonam Bogra1, Saurabh Kumar Gupta1, S Vijay Singh2, Radhika Goyal1, Madhur Bogra1,  
1 Department of Conservative Dentistry and Endodontics, J.N. Kapoor D.A.V. Dental College, Yamunanagar, Haryana, India
2 Department of Dentistry, NEIGRIHMS, Shillong, Meghalaya, India

Correspondence Address:
Nikita Goyal
House No. 9, Thandi Sadak, RadhaKrishan Enclave, Backside of Maharaja, Malerkotla, Punjab


Context: Nowadays, dentists use tooth-colored materials extensively, but the bond strength of these materials with teeth is crucial to determine their long-span durability. As a result, the bond strength of these materials must be assessed. Aims: This study aimed to compare the push-out bond strength of alkasite restorative material and bulk-fill composite when used with a universal adhesive system. Settings and Design: In vitro study to determine the push-out bond strength with a universal testing machine. Subjects and Methods: Forty extracted mandibular molars were taken and their occlusal surface was wet grounded with silicon carbide paper so that a smooth dentin surface was obtained. Class I cavities were prepared with a template to standardize the size of the preparation. Teeth were divided into Group I and Group II of 20 teeth each. Alkasite restorative material was used in Group I, and nanohybrid bulk-fill composite was used in Group II. Restored samples were sliced into 2 mm thick sections and examined for push-out bond strength. Results: Push-out bond strength of Cention-N was 201.25 and the composite was 163.69, and the results were statistically significant (P = 0.017). Statistical Analysis Used: Unpaired t-test. Conclusions: It was concluded that alkasite material had more push-out bond strength than bulk-fill composite when used with a universal adhesive system.

How to cite this article:
Goyal N, Bogra P, Gupta SK, Singh S V, Goyal R, Bogra M. Push-out bond strength of alkasite restorative material and bulk-fill composite used with universal adhesive system: An in vitro study.Indian J Dent Sci 2023;15:33-36

How to cite this URL:
Goyal N, Bogra P, Gupta SK, Singh S V, Goyal R, Bogra M. Push-out bond strength of alkasite restorative material and bulk-fill composite used with universal adhesive system: An in vitro study. Indian J Dent Sci [serial online] 2023 [cited 2023 Nov 29 ];15:33-36
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Due to the esthetic demands of patients, composite resins are the material of choice among restorative materials.[1] However, the composite material has a significant limitation of polymerization shrinkage, which can be compensated by the incremental technique making it a technique-sensitive and time-consuming material.[2],[3] Hence, bulk-fill restorative materials have been introduced, which can be cured up to 4 mm. Tetric N Ceram is one such bulk-fill material used in the present study. The newer bulk-fill materials have shown excellent mechanical properties but still have a limitation of polymerization shrinkage and lack of anticariogenic properties.[4]

New bioactive alkasite dental restorative materials (e.g., Cention-N) were launched in dentistry to overcome the shortcomings present in these restorative materials.[5] Cention-N is a tooth-colored, radiopaque material which liberates fluoride, calcium, and hydroxide ions. Cention-N can be cured with visible blue light in addition to self-curing.[1],[6] Hence, in the present study, the push-out bond strength of alkasite bioactive restorative material was compared with nanohybrid bulk-fill composite using a universal adhesive system.

It was hypothesized that there would be no difference between the push-out bond strength of alkasite restorative material and bulk-fill composite.

 Subjects and Methods

Forty extracted mandibular molars were rinsed with flowing water to remove any debris, blood, etc. Scaler was used to remove the calculus and it was followed by polishing with pumice slurry and a rubber prophylaxis cup. Teeth were rinsed and then allowed to dry in the air followed by storage in distilled water with thymol at 37°C for not more than 3 months. 400–600 silicon carbide paper was used to wet-grind the occlusal surface of the crown till a flat dentin surface was reached.

While preparing samples, uniform box-type Class I cavities of 4 mm × 4 mm and a depth of 4 mm were prepared using straight fissure diamond burs with air rotor under the air-water spray. A template was designed to standardize the cavity dimensions.

Two materials were chosen for the study, i.e., Cention-N, an alkasite bioactive material, and Tetric N Ceram, a bulk-fill composite.

To compare push-out bond strength, on a random basis, teeth were divided into two main groups: Group I and Group II of 20 teeth each. Samples of Group I and Group II were restored with alkasite restorative material and bulk-fill composite, respectively. The restored tooth samples of Group I and Group II were sliced into 2 mm dentin samples after storing them in distilled water for 24 h. The sliced samples were evaluated for a push-out bond strength test under the universal testing machine. The obtained results were statistically analyzed.


Descriptive statistics was performed by calculating mean and standard deviation for the continuous variables. The mean push-out bond strength of Cention-N was 201.5 and Composite was 163.69 [Figure 1] and [Figure 2]. When unpaired t-test was performed, the t-test value was 2.97 (P=0.017). On statistical evaluation mean pushout bond strength of Cention-N was significantly higher as compared to Tetric N Ceram.{Figure 1}{Figure 2}


Nanohybrid bulk-fill and bioactive restorative materials were compared in Class I cavities. Mandibular molars with large occlusal surfaces were used in this study as samples because the large surface area allows easier sectioning at various levels.

In this study, composite resins were the material of choice as it is the most commonly used direct material nowadays, and it has micromechanical properties similar to dentin. It is highly esthetic and has mechanical bonding with tooth structure, requiring minimal tooth preparation.[3],[7] In most studies related to composite placement techniques, increments of 2 mm thickness are used for composite placement and proper polymerization of the composite material. Nevertheless, while performing this technique, sometimes air bubble incorporation and contamination between the increments may occur, and also, it is more time and effort-consuming. Manufacturers introduced “bulk-fill” composites to overcome these disadvantages in dentistry. Bulk-fill materials (e.g., Tetric N-Ceram Bulk Fill) can be cured to the thickness of 4 mm, so large increments can be used, leading to less entrapment of bubbles, less polymerization shrinkage, and less time-consuming.[8] However, bulk-fill material also has drawbacks such as polymerization shrinkage stress, low flexural strength, and no anticariogenic or bioactive property.[9]

A newly introduced material, Cention-N, is an “alkasite,” tooth-colored bulk-fill material. Cention-N liquid contains four monomers, i.e., urethane dimethacrylate (UDMA), aromatic aliphatic-UDMA, dicalcium phosphate, and polyethylene glycol-400 dimethacrylate (PEG–400 DMA). The powder part contains five fillers, i.e., barium aluminum silicate glass filler for strength, ytterbium trifluoride for radiopacity, isofiller to relieve shrinkage stress, calcium barium aluminum fluorosilicate for strength and fluoride release, and calcium fluorosilicate (alkaline glass filler) for release of fluoride ions (F−), calcium and hydroxide (OH− and Ca2+) ions which provide anticariogenic properties.[1] The mixed material contains 24.6% weight of alkaline glass fillers. Ions released by the material depend on the pH of the oral cavity, a greater amount is released at acidic pH than at neutral pH. Cention-N can be used as bulk-fill material in thickness >4 mm in self-cure/dual-cure mode.[8] In the present study, Cention-N was dual-cured and it was used with a universal adhesive. Tetric N-Bond Universal was used as adhesive with both the materials, i.e., Tetric N Ceram and Cention-N. Tetric N-Bond Universal was used in total-etch mode.

For the present study, standardized preparation (4 mm × 4 mm) was prepared on 40 extracted teeth, further split into two main groups of 20 teeth each, Group I and Group II. Cention-N was used to restore Group I, and Tetric-N-Ceram was used to restore Group II and after that push-out bond strength was measured.

The obtained results show that the mean bond strength of Group I (201.25) was more than Group II (163.69) and the results were statistically significant (P = 0.017) [Figure 1]. In agreement with these results, Mazumdar et al.[5] found that Cention-N had a substantially greater bonding strength than Tetric N Ceram. Another study conducted by Naz et al.[10] compared alkasite (Cention N) with glass ionomer cement and nanohybrid composite and reported that alkasite (Cention N) had the highest shear bond strength values with dentine among the other tested groups. Bhat et al.[11] also concluded that Cention-N with bonding agent exhibited minimum microleakage and had maximum shear bond strength compared to other restorative materials. This was probably due to the depth of cure of the materials. Although both the materials were light-cured, Cention-N has a dual-cure property, i.e., when additionally light-cured, it can speed up the polymerization reaction of Cention-N and lead to better mechanical properties.[12] Cention-N contains aromatic aliphatic-UDMA, a hydrophobic component that combines the favorable properties of aliphatic and aromatic diisocyanates, and PEG-400 DMA, which has a hydrophilic character, due to which Cention-N has better wetting properties and hence, adapts readily to the enamel and prepared tooth surface. When polymerized with inorganic fillers, these monomer components provide a high level of polymer density and degree of polymerization over the full depth of the restoration.[1],[13] Gomes de Araújo-Neto et al.[14] also concluded that the degree of conversion and maximum polymerization rate was more in Cention-N than in Tetric N Ceram bulk fill. Hence, a solid acid-resistant resin dentin interdiffusion zone, i.e., hybrid layer, was formed between the restoration (Cention-N) and the tooth interface, leading to higher bond strength. The mechanical behavior of restorative material depends on the size of the particles and concentration of the inorganic fillers; the filler particle size of Cention-N is 0.1 μm, i.e., lower in comparison with Tetric N Ceram, which is 0.7 μm leading to increased filler load in Cention-N which also enhances its fracture strength.[5] Cention-N also exhibits lower water absorption than Tetric N Ceram because it contains four dimethacrylates in liquid with UDMA as the main component that lacks a hydroxyl side group, making it hydrophobic. Hence, it exhibits lower water absorption. While in Tetric N Ceram, Bisphenol glycol dimethacrylate (Bis-GMA) is a hydrophilic monomer leading to higher water absorption, resulting in lower bond strength. Furthermore, shrinkage force in Tertic N Ceram is higher (110N) than Cention-N (86.9N), which could have resulted in lower bond strength in Tetric N Ceram.[1],[15],[16],[17] Tetric N Ceram has higher viscosity leading to higher polymerization shrinkage stress and the possibility of gaps at the margins if stress exceeds the bond strength of adhesives to the residual tooth structure.[18]

Cention-N has more push-out bond strength than Tetric N Ceram. Hence, null hypothesis was rejected in this study.

However, a large sample size and clinical studies are recommended to substantiate the results further.


It may be concluded from the study that alkasite material has more push-out bond strength than nanohybrid composite when used with a universal adhesive system.

Ethical clearance

Since the study was an laboratory study no ethical clearance was required.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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