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ORIGINAL RESEARCH  
Year : 2019  |  Volume : 30  |  Issue : 3  |  Page : 403-407
Comparative evaluation of microleakage around Class V cavities restored with alkasite restorative material with and without bonding agent and flowable composite resin: An in vitro study


1 Department of Conservative Dentistry and Endodontia, Swargiya Dadasaheb Kalmegh Smruti Dental College, Nagpur, Maharashtra, India
2 Department of Oral and Maxillofacial Surgery, Govt Dental College and Hospital, Mumbai, Maharashtra, India
3 Department of Oral and Maxillofacial Pathology, Swargiya Dadasaheb Kalmegh Smruti Dental College, Nagpur, Maharashtra, India

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Date of Web Publication9-Aug-2019
 

   Abstract 

Background: Marginal adaptability of restorative material is one of the prime factors for success of a restoration. Aim: To evaluate microleakage at enamel restoration and dentin restoration interface of Class V cavities restored with new alkasite restorative material Cention-N, with and without using bonding agent and flowable composite resin. Materials and Methods: Thirty Class V tooth preparations were divided into three groups (n = 10): Group-I restored with Cention-N (Ivoclar Vivadent) without adhesive, Group-II was restored with Cention-N after application of eighth-generation bonding agent (3M ESPE, Single Bond Universal Adhesive), and Group-III was restored with flowable composite resin (Tetric-N-Flow, Ivoclar Vivadent). All samples were subjected to 200 thermocycles between temperature baths at 5°C and 55°C. All samples were cut longitudinally through the center of the restorations with the help of isomet diamond saw. The sections were then observed under binocular stereomicroscope at 20×. Two evaluators scored the depth of dye penetration independently at enamel and dentin margins. Statistical Analysis: Kruskal–Wallis nonparametric analysis followed by Dunn's multiple comparison tests were done to evaluate differences among the experimental groups. Mann–Whitney test was used to compare the difference between occlusal and gingival scores within each restoration. Results: Microleakage seen in decreasing order: Cention-N without adhesive >Flowable composite >Cention-N with adhesive. Conclusion: Microleakage at enamel restoration interface was less than microleakage at dentin restoration interface of each group, but the difference was not statistically significant. Least microleakage was seen with Cention-N with adhesive followed by flowable composite. More microleakage was seen with Cention-N without adhesive.

Keywords: Bonding agent, Cention-N, flowable composites, microleakage, polymerization shrinkage

How to cite this article:
Meshram P, Meshram V, Palve D, Patil S, Gade V, Raut A. Comparative evaluation of microleakage around Class V cavities restored with alkasite restorative material with and without bonding agent and flowable composite resin: An in vitro study. Indian J Dent Res 2019;30:403-7

How to cite this URL:
Meshram P, Meshram V, Palve D, Patil S, Gade V, Raut A. Comparative evaluation of microleakage around Class V cavities restored with alkasite restorative material with and without bonding agent and flowable composite resin: An in vitro study. Indian J Dent Res [serial online] 2019 [cited 2019 Dec 8];30:403-7. Available from: http://www.ijdr.in/text.asp?2019/30/3/403/264131

   Introduction Top


One of the important factors for the success of a restoration is its marginal seal. Restoration of Class V cavities is always a challenge at dentin interface where no enamel is present for bonding. Dentin at gingival margin shows higher organic components, tubular structure, fluid pressure, and the lower surface energy that make bonding more difficult than enamel.[1]

Since 1996, flowable composites were used to restore Class V cavities. Flowable composite resins, though widely used for restorations, have certain limitations such as polymerization shrinkage. This shrinkage results in gap formation between the tooth and the restoration and leads to subsequent problems such as marginal discoloration of restored tooth, recurrent caries at the tooth restoration interface, hypersensitivity, pulpal inflammation, thus influencing the longevity of dental restoration.[2],[3]

Various researches are being carried out to fulfill the requirements of clinicians for ideal restorative material. One of the outcomes of the studies is an alkasite restorative material, Cention-N [Ivoclar Vivadent]. It is a subgroup of composite resin material such as compomer or ormocer. The powder contains various glass fillers that are capable of releasing alkaline ions-like fluoride, calcium, and hydroxyl that can neutralize acidic ions surrounding to the restoration. Liquid contains monomer that enhances the flowability of the material and adapts to the smear layer. It is a dual-cured, tooth-colored restorative material available in powder and liquid form.[4]

Cention-N contains 78.4% of inorganic filler. The alkaline glass counts for 24.6% in weight of the final material. This releases substantial levels of fluoride ions comparable to those released by traditional glass ionomer cements (GICs). In addition to fluoride ions, the alkaline glass also releases hydroxide ions and calcium ions, which can further help prevent demineralization of the tooth substrate. The long-term release of calcium ions and fluoride ions from Cention-N in acidic conditions is highest in comparison with traditional GIC.[4]

Till date, no research has been carried out to check microleakage of alkasite material and flowable composites in Class V tooth preparations. The null hypothesis tested was that there is no significant difference between alkasite material and flowable composite resin in microleakage at enamel restoration and dentin restoration interface.


   Materials and Methods Top


Fifteen recently extracted sound human permanent molars were selected. Selection criteria for teeth were absence of caries, restoration, and lack of evidence of cracks or white spot on buccal and lingual surface. All samples were cleaned and stored in distilled water. Thirty Class V cavities, one on the lingual and another on the buccal surface of each tooth, were prepared with a high-speed flat-end straight diamond point (SF-41 ISO 109/010 Mani Dia-Burs) with water as coolant. After every fifth cavity preparation, the bur was replaced. Cavities were prepared in such a way that occlusal margin was in enamel and gingival margin was in dentin. The preparation was standardized to 2 mm in depth, 4 mm mesio-distal width, and 2 mm height in occluso-gingival direction. The measurements were taken milimetrically using a periodontal probe. All the preparations were done by a single operator. All 30 tooth preparations were randomly divided into three groups of five teeth, consisting of ten cavities each (n = 10).

  • Group I: Cention-N (Ivoclar Vivadent) without adhesive was placed in bulk in the prepared cavities. It sets by self-polymerization, no light cure was done
  • Group II: Eighth-generation bonding agent [3M ESPE, Single Bond Universal Adhesive] was applied and light cured (Bluephase, Ivoclar Vivadent) for 20 s, then Cention-N was placed in bulk and light cured for 20 s
  • Group III: Eighth-generation bonding agent was applied and light cured for 20 s, then flowable composite resin (Tetric-N-Flow, Ivoclar Vivadent) was placed in bulk and light cured for 20 s.


All restored teeth were stored in distilled water at 37°C and finished after 24 h with abrasive discs (Sof-Lex 3M ESPE, St Paul, USA) fine grit diamond burs. Teeth were stored in distilled water for seven days at 37°C. Then they were subjected to 200 thermocycles between temperature baths at 5°C and 55°C. Cycle in each bath lasted for 30 seconds with a transfer time of 10 seconds. The root apices were sealed with composite resin and the teeth were painted with two coats of nail varnish to within 1 mm of the margins of the restorations. The samples were immersed in methylene blue dye [Always, Wadi, Nagpur] for 24 h at 37°C. Then they were washed for 1 min under running tap water and dried. An isomet diamond saw was used to cut the teeth longitudinally through the center of the restorations under water coolant. All sections were observed under binocular stereomicroscope at 20×. Representative stereomicroscopic photographs are shown in [Figure 1], [Figure 2], [Figure 3]. Two evaluators scored the depth of dye penetration independently at enamel and dentin margins. The samples were coded and mixed for blending, so that the evaluators could not identify the group of samples. For each type of restoration, the section with greater leakage was selected for scoring.
Figure 1: Digital photograph of a specimen shows no dye penetration at restoration enamel and restoration dentin junction – “Score-0”

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Figure 2: Restoration enamel junction shows dye penetration up to half of cavity depth – “Score-1” and restoration dentin junction shows microleakage more than half of the depth of cavity wall – “Score-2”

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Figure 3: Specimen shows dye leakage involving axial wall – “Score 3”

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Scoring system used was similar to that used by Munro, Hilton, and Hermesch.[5] Value and its inference used in the present study are as follows:

Score 0 – No evidence of microleakage [Figure 1]

Score 1 – Dye penetration up to half of cavity depth [Figure 2], enamel restoration junction]

Score 2 – Microleakage more than half of the depth of cavity wall [Figure 2], dentin restoration junction]

Score 3 – Dye leakage involves axial wall [Figure 3].

Mean leakage scores for all groups were calculated. The scores were analyzed with Kruskal–Wallis nonparametric analysis followed by Dunn's multiple comparison test to evaluate differences among the experimental groups at a significant level of P = 0.05. Combined occlusal and gingival scores within each restoration were compared using the Mann–Whitney test.


   Results Top


Microleakage values for all groups were greater at dentin restoration junction as compared to those at enamel restoration interface. However, the difference was not statistically significant. Difference in microleakage values at enamel restoration junction between Group I (35.5) and Group II (16.5), Group I (35.5) and Group III (13.5) was highly significant (P < 0.001), and Group II and Group III was insignificant (P > 0.05). Comparison is given in [Table 1]. Difference in microleakage at dentin restoration junction in Group I (31.9) and Group II (10.1) and Group I and Group III (18) was significant (P < 0.001), whereas, difference of microleakage between Group II (10.1) and Group III (18.0) was insignificant (P > 0.05). Comparison is given in [Table 2].
Table 1: Pairwise comparison of mean microleakage at enamel restoration interface using Dunn's multiple comparison test

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Table 2: Pairwise comparison of mean microleakage at dentin restoration interface using Dunn's multiple comparison test

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   Discussion Top


Restoration of Class V cavities requires meticulous placement of restorative material, especially at cervical wall where only dentin is present. Microleakage is the clinically undetectable passage of bacteria, fluids, molecules, or ions in microgaps (10−6 μm) between a cavity wall and the restorative material applied to it. To evaluate microleakage, methylene blue dye was used in this study. The diameter of dye molecules is 0.80 nm that is less than the diameter of dentinal tubules (1–4 μm).[6]

In the present study, to simulate thermal changes as that seen in the oral cavity, thermocycling was performed. It is an in vitro process of subjecting a restoration and tooth to temperature extremes that conform to those found in the oral cavity.[7]

Class V cavities restored with Cention-N without adhesive showed more leakage at enamel restoration junction (35.500) compared to cavities restored with Cention-N with adhesive (16.500) and flowable composite (13.500). At dentin restoration junction, more microleakage was seen with Cention-N without adhesive (31.900) than Cention-N with adhesive (10.100) and flowable composite (18.000). Microleakage is observed between tooth and restorative material because micromechanical locking is limited to surface roughness induced by diamond burs during tooth preparation. Our findings are in accordance with those of Manuela Lopes.[8]

Restorations with flowable composites using bonding agent demonstrate least microleakage (13.500) at enamel restoration junction than Cention-N with adhesive (16.500) and Cention-N without adhesive (35.500). However, dye leakage at dentin restoration interface (18.000) was more than Cention-N with adhesive (10.100) and less than Cention-N without adhesive (31.900).[9] Our findings are similar to Yazici et al.,[5] Peutzfeldt and Asmussen,[10] and Attar et al.[11] who found less leakage at enamel restoration interface. Because flowable composite resin has less filler content resulting in low viscosity, high flowability, and the coefficient of thermal expansion is close to that of the tooth structure. They have low modulus of elasticity that allows for plastic deformation and absorbs polymerization shrinkage. They are rich in resin, have low viscosity, and flow. It adapts well to the margins of prepared tooth.[12],[13]

Cavities restored with Cention-N with adhesive show less leakage between restoration and tooth structure, because interface is largely sealed as an acid resistant, resin-dentin interdiffusion zone, i.e. hybrid layer. Our findings are similar to that of the study conducted by Manuela Lopes.[8]

The isofiller present in Cention-N powder acts as shrinkage stress relief. The liquid consists of four different dimethacrylates (DMAs), initiators, and other additives. A combination of urethane dimethacrylate (UDMA), tricyclodecan-dimethanol dimethacrylate (DCP), an aromatic aliphatic-UDMA, and polyethylene glycol 400 (PEG-400) DMA cross-links during polymerization to form strong mechanical properties and good long-term stability. UDMA is a main component of monomer matrix that provides moderate viscosity and strong mechanical properties. DCP is a low-viscosity, difunctional monomer that enables hand manipulation. Aromatic aliphatic-UDMA combines a favorable property of aliphatic that is low tendency to discolor and aromatic diisocynates provides stiffness. PEG-400 DMA is a liquid monomer that enhances the flowability and adapts to the smear layer.[4],[14]

Cention-N exhibits a high polymer network density and degree of polymerization over the depth of the restoration because it uses sole cross-linking methacrylate monomer in combination with stable, efficient, self-cure initiator.[4]

Cention-N includes special patented filler (partially functionalized by silanes) which keeps shrinkage stress to a minimum. Whereas, the organic/inorganic ratio as well as the monomer composition of the material is responsible for the low volumetric shrinkage.

When material polymerizes, either in self-cure or additional light cure mode, the monomer chains located on the fillers together with the silanes begin a cross-linking process and forces between the individual fillers come into action, which place stress on the cavity walls. This stress is influenced by both volumetric shrinkage and the modulus of elasticity of the material. Due to its low elastic modulus (10 GPa), the shrinkage stress reliever within Cention-N acts like spring (i.e. it expands slightly as the forces between the fillers grow during polymerization) among the standard glass fillers, which have a higher elastic modulus of 71 GPa.

The silanes bonded to the filler particles improve the bond between the inorganic filler and the monomer matrix as they are able to establish a chemical bond between the glass surface and the matrix. Ultimately, the volumetric shrinkage and shrinkage stress in Cention-N are reduced during polymerization, allowing bulk increments to be placed.[4] Use of dentin bonding agents improves marginal seal of restorative material and tooth interface. They have proven to be effective at reducing but not eliminating microleakage.[12]

Our results are based on in vitro study. Future research to evaluate the clinical performance of alkasite material is required. Clinically, features such as hypersensitivity, marginal discoloration, and other criteria traditionally associated with microleakage may be more reliable on the overall caries risk of patient.[15]


   Conclusion Top


Within the limitation of this in vitro study, the following conclusions can be drawn. Microleakage at enamel restoration interface was less than microleakage at dentin restoration interface of each group, but the difference was statistically not significant. At enamel restoration interface, least leakage was seen with flowable composite resin restoration followed by Cention-N with adhesive and then Cention-N without adhesive. At dentin restoration interface, Cention-N with adhesive shows better marginal adaptability followed by flowable resin composite and Cention-N without adhesives.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Pashley DH and Carvalho RM. Dentin permeability and dentin adhesion. J Dent 1997;25:355-72.  Back to cited text no. 1
    
2.
Craig RG. Craig's Restorative Dental Materials. 13th ed. St Louis Mosby; 2012 p. 65-70.  Back to cited text no. 2
    
3.
Going RE. Microleakage around dental restorations: A summarizing review. J Am Dent Assoc 1972;84:1349-57.  Back to cited text no. 3
    
4.
Scientific Documentation: Cention-N. Ivoclar Vivadent, September 2016  Back to cited text no. 4
    
5.
Yazici AR, Baseren M, Dayangac B. The effect of flowable resin composite on microleakage in Class V cavities. Oper Dent 2003;28:42-6.  Back to cited text no. 5
    
6.
Kidd EAM. Microleakage: A review. J Dent 1976;4:199-206.  Back to cited text no. 6
    
7.
Alani AH, Toh CG. Detection of microleakage around dental restoration: A review. Oper Dent 1997;22:173-85.  Back to cited text no. 7
    
8.
Manuela Lopes. Ultramorphological study of the interface: Dentin-Cention N as a function of saliva contamination and the usage of an adhesive system. Scientific documentation of Cention N; 2015.  Back to cited text no. 8
    
9.
Prati C, Nucci C, Montanari G. Shear bond strength and microleakage of dentin bonding system. Journal of Prosthetics Dentistry 1991;65:401-7.  Back to cited text no. 9
    
10.
Peutzfeldt A, Asmussen E. Composite restorations: Influence of flowable and self curing resin composite lining on microleakage in vitro. Oper Dent 2002;27:569-75.  Back to cited text no. 10
    
11.
Attar N, Tam LE, McComb D. Flow, strength, stiffness and radiopacity of flowable composites. J Can Dent Assoc 2003;69:516-21.  Back to cited text no. 11
    
12.
Bayne SC, Thompson JY. A characterization of first generation flowable composite. J Am Dent Assoc 1998;129:567-77.  Back to cited text no. 12
    
13.
Thomazatti D, Alexindra M, Pereira R. In vitro evaluation of microleakage of flowable composite in Class V restorations. Braz Dent J 2002;13:184-7.  Back to cited text no. 13
    
14.
Moszner N, Fischer UK. A partially aromatic urethane dimethacrylate as a new substitute for bis-GMA in restorative composites. Dent Mater 2008;24:694-9.  Back to cited text no. 14
    
15.
John Burgess. Microleakage of Cention N compared to dental amalgam. Final report. Scientific documentation – Cention-N; May 2015.  Back to cited text no. 15
    

Top
Correspondence Address:
Dr. Priyatama Meshram
Department of Conservative Dentistry and Endodontics, Swargiya Dadasaheb Kalmegh Smruti Dental College and Hospital, Nagpur, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdr.IJDR_767_17

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