Journal of Conservative Dentistry

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 21  |  Issue : 5  |  Page : 485--490

Clinical evaluation of self-adhering flowable composite versus conventional flowable composite in conservative Class I cavities: Randomized controlled trial


Omar Osama Shaalan, Eman Abou-Auf, Amira Farid El Zoghby 
 Department of Conservative Dentistry, Faculty of Dentistry, Cairo University, Cairo, Egypt

Correspondence Address:
Dr. Omar Osama Shaalan
35 Mohamad Farid Street El Hay El Motamayz, Sixth of October City, Giza
Egypt

Abstract

Background: Self-adhering flowable composite (SAFC) minimized the time-consuming application procedures encountered with the traditional adhesive systems and restorative materials. Self-adhering composite combines the merits of both adhesive and restorative material technologies (8th generation) in a single product, bringing new horizons, and ambitions to restorative procedures. Aim: The aim of this study was to evaluate the clinical performance of SAFC compared to conventional flowable composite in conservative Class I cavities. Materials and Methods: In a split-mouth design, after cavity preparation, 18 patients with conservative Class I cavities received randomly two pairs of restorations, either Vertise™ flow or Filtek™ Z350 XT Flowable combined with Scotchbond™ Universal Etchant and Single Bond Universal, all materials were applied according to the manufacturer's instructions. Restorations were evaluated at baseline and after 6 months by two calibrated assessors using the modified United States Public Health Service criteria measuring (retention, postoperative hypersensitivity, color match, marginal adaptation, and marginal discoloration). Statistical Analysis: Chi-square test was used to compare between flowable composite materials after different follow-up periods, Wilcoxon signed-rank test was used to explore changes over follow-up periods. A value of P ≤ 0.05 was considered statistically significant. Results: At baseline and 6 months, there was no statistically significant difference between both materials for all tested outcomes. Conclusions: SAFC has shown clinical performance similar to conventional flowable composite after 6 months of clinical service.



How to cite this article:
Shaalan OO, Abou-Auf E, El Zoghby AF. Clinical evaluation of self-adhering flowable composite versus conventional flowable composite in conservative Class I cavities: Randomized controlled trial.J Conserv Dent 2018;21:485-490


How to cite this URL:
Shaalan OO, Abou-Auf E, El Zoghby AF. Clinical evaluation of self-adhering flowable composite versus conventional flowable composite in conservative Class I cavities: Randomized controlled trial. J Conserv Dent [serial online] 2018 [cited 2020 Oct 31 ];21:485-490
Available from: https://www.jcd.org.in/text.asp?2018/21/5/485/241192


Full Text

 Introduction



Conventional resin composites are the standard materials used in the restoration of conservative Class I cavities. However, these materials have a high modulus of elasticity, low flowability, low tendency for stress relaxation, and difficulty to be placed in conservative tooth preparations.[1] Flowable composites provided excellent handling characteristics using a syringe delivery system which overcomes some of the obstacles encountered during the placement of resin composite in small-to-moderate-sized cavities, especially in inaccessible areas.[2]

Minimally invasive Class I restorations have gained widespread use because of their pleasing esthetics and conservation of sound tooth structure. Although flowable composites are widely used by dental professionals, their clinical applications have been restricted to some degree by their mechanical shortcomings found, especially in early generation flowable composites.[1]

Introduction of nanotechnology to flowable composites enhanced their mechanical properties, allowing them to attain or overcome some regular viscosity resins. Its fluidity provided better adaptation to the inner walls and cervical region, besides an easier clinical placement so they may become a material of universal indication. However, the bonding procedures during application of flowable composite in conservative Class I cavities need further simplification.[3]

Self-adhering flowable composite (SAFC) combines the merits of both adhesive and restorative material technologies (8th generation) in a single product, bringing new horizons, and ambitions to restorative procedures. SAFC provides the least possible chair time, allowing fewer steps, providing less chance for errors, and providing shorter treatment sessions for the patient with multiple restorations accomplished in the same visit, this is of great value, especially for uncooperative or mutilated patients.[4],[5]

With the limited evidence-based information in the literature about using SAFC in conservative Class I restorations, it was found beneficial to evaluate the newly introduced material using a randomized controlled trial to test the null hypothesis that SAFC will have the same clinical performance as conventional flowable composite in conservative Class I cavities.

 Materials and Methods



All procedures performed in this study were in accordance with the ethical standards of Research Ethics Committee of Faculty of Dentistry, Cairo University, (Ref. 16/4/12), informed consent was obtained from all participants. A protocol was registered in Pan African Clinical Trial Registry (PACTR) database “PACTR201602001477364.” The sample size was calculated using PS (Power and Sample Size Calculation), version 3.1.2 for windows based on the previous study,[6] which indicated that the probability of success among controls was 0.33. If the true probability of success among cases was 0.83, it was needed to study 14 case patients and 14 control restorations to be able to reject the null hypothesis that the success rates for case and controls are equal with probability (power) 0.8. This was increased to 18 restorations in each group to compensate for losses during follow-up.

Eligibility criteria of participants

Inclusion criteria of participants were patients with bilateral occlusal small Class I carious lesions; age 19–40 years and good oral hygiene. Exclusion criteria of participants were systemic disease or severe medical complications; allergic history concerning methacrylates; rampant caries; pregnancy; disabilities; heavy smoking; xerostomia; and lack of compliance; evidence of severe bruxism, clenching, or temporomandibular joint disorders.

Eligibility criteria of teeth

Inclusion criteria of teeth were small Class I carious lesion in occlusal pits and fissures; cavity preparation should not extend to stress bearing areas. Exclusion criteria of the teeth were deep carious defects; periapical or pulpal pathology; tooth hypersensitivity; possible prosthodontic restoration of teeth; heavy occlusion; endodontically treated teeth; and severe periodontal affection.

Recruitment

Participants were enrolled 1 month before the intervention, from which eligible patients were recruited to fulfill the eligibility criteria [Figure 1].{Figure 1}

Allocation of participants

Simple randomization was done by generating numbers from 1:18 using random sequence generator (Randomness and Integrity Services Ltd). Each generated random number represented assigning materials either to the right or left sides randomly in a split-mouth design. The operator chose between numbers in an opaque sealed envelope, which was arranged by the assistant, who was not involved in any of the phases of the clinical trial. The operator was not blinded to the material assignment because of the difference in the application protocol of the restorative materials; however, the assessors and participants were blinded to the material assignment.

Cavity preparation

Patients were given local anesthesia as required; teeth were isolated using rubber dam (Sanctuary Health Sdn Bhd). No. #330 (Mani, Inc., Japan) bur (0.8 mm in diameter and 1.6 mm in length) in a high-speed handpiece with copious irrigation was used to prepare conservative Class I cavity preparations, with facio-lingual width not exceeding ¼ intercuspal distance, away from functional areas which were determined using articulating paper.

Materials application

Restorative materials were assigned randomly into two groups as follows: Vertise™ flow, Kerr, Orange, CA, USA (SAFC) and Filtek™ Z350 XT Flowable, 3M ESPE, USA ( conventional flowable composite) combined with universal adhesive system ( Scotchbond Universal Etchant and Single Bond Universal, 3M ESPE, USA). All materials were applied according to the manufacturers' instructions [Table 1]. All restorations were finished using flame-shaped finishing stone (Mani, Inc., Japan) and polished using Opti1step (Kerr, Orange, CA, USA). [Figure 2] shows the procedures of cavity preparation, material application, and different follow-up evaluations. Modified United States Public Health Service (USPHS) criteria were used to evaluate dental restoration by two blinded assessors at baseline and after 6 months when assessors had different scores, they discussed to reach for a consensus [Table 2].{Table 1}{Figure 2}{Table 2}

Statistical analysis

Statistical analysis was performed with IBM ® SPSS ® (SPSS Inc., IBM Corporation, NY, USA) Statistics version 25 for Windows. Chi-square test was used to compare between tested materials. Wilcoxon signed-rank test was used to explore changes over follow-up periods (1 week and 6 months). A value of P ≤ 0.05 was considered statistically significant.

 Results



The results of the current study have revealed no statistically significant difference between both materials for all tested outcomes at baseline and after 6 months. [Table 3] shows frequency (n) and percentage of outcomes assessed according to the Modified USPHS criteria for different materials.{Table 3}

 Discussion



The available data in the literature regarding the use of flowable composite in posterior restorations are limited and did not present conclusive evidence. Moreover, the large variability of products in this category may lead to different experimental results.[7] The reduced filler loading in early generation flowable composites impaired the wear resistance of the restorations during the function. Due to their inferior mechanical properties, flowable composites were not recommended as restorative materials, especially in cavities with high-stress occlusal function.[8]

In small Class I cavities, no heavy occlusal loads are expected to occur, as most of the functional stresses are absorbed by the remaining tooth structure. A systematic review was conducted regarding the usage of the flowable composite in minimally invasive cavities and noncarious cervical lesions. Despite limited data in the literature about flowable composite, but the best available evidence in databases recommends using flowable composite in conservative minimally invasive cavities.[9]

SAFC is a new material introduced to the dental market. This material is claimed to eliminate the need for a separate bonding step, thus simplifying the restorative procedure. For this reason, SAFC may be considered to start the 8th generation of dental adhesive systems or to represent a cross-link between all-in-one adhesive systems and flowable composite.[10] Vertise Flow is a SAFC with a pH of mild aggressiveness ~1.9, which is based on the adhesive technology that uses a functional monomer (glycerophosphate dimethacrylate [GPDM]) to etch enamel and dentin, and a hydrophilic monomer (e.g., hydroxyethyl methacrylate) to enhance wetting and resin infiltration into dentin substrate. This resin bonds in a dual manner; chemically between the functional monomer and the hydroxyapatite of tooth structure and micromechanically between the polymerized resin of SAFC and collagen fibers and smear layer of dentin.[5]

A functional monomer such as 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) can form stable complexes of calcium–phosphate.[11] GPDM is another functional monomer that has the advantage of having two polymerizable groups that can react with other monomers in adhesive systems and resin composite; this improved quality of the polymer network and enhanced mechanical properties.[12] However, GPDM revealed hydrophilicity, and greater demineralization of dentin than bonding to calcium of hydroxyapatite, producing unstable complex of di-calcium phosphate dehydrate deposited on hydroxyapatite surface that will dissolve gradually in aqueous environment thus deteriorating the interfacial integrity.[13]

Filtek Z350 XT flowable was selected as the comparator; it is a nano-filled flowable composite with filler loading of 65% by weight and particle size of 0.6:1.4 μm, which was comparable to Vertise Flow with filler loading 70% by weight and particle size of ~1 μm. Filtek Z350XT flowable was combined with Scotchbond Universal Etchant and Single Bond Universal, containing functional monomer MDP capable of chemical bonding, this was important for the quality and durability of bonding.[14] It was preceded by acid etching for better bonding performance, especially with enamel.[15]

After 6 months, all restorations were evaluated with no dropouts; the retention rate was 100%. In the current study, SAFC has shown clinical performance similar to conventional flowable composite after 6 months of clinical service; therefore, the null hypothesis was accepted. Limited clinical data were available in the literature about clinical performance of SAFC.[7] One study evaluated the performance of the material in noncarious cervical lesions; it has shown loss of retention after 6 months only, with a failure rate of 66%, the clinical performance of SAFC was found to be unacceptable clinically after 6 months of clinical service. The inferior bonding performance of the material was due to lack of macro-mechanical retention and insufficient micro-mechanical retention between the restoration and tooth structure due to limited etching ability of SAFC and inadequate removal of the smear layer.[6] Another study [16] evaluated the clinical performance of SAFC as pit and fissure sealant; it was the least retentive material, despite preceeding it with acid etching, this may be attributed to its diminished flowability.

Three studies evaluated SAFC in minimally invasive Class I cavities.[7],[17],[18] The results have shown that SAFC performed similar to conventional flowable composite when used in conservative Class I cavities, which was in agreement with the outcome of this research. In small-sized cavities, the use of a flowable composite as a stand-alone restoration has been recommended.[7],[9],[19] In Class I cavity preparations even in minimally invasive designs, the presence of macromechanical retention enhanced the overall clinical performance of SAFC, unlike when used as pit and fissure sealant or in noncarious cervical lesions, this may be the reason for the performance of SAFC in minimally invasive Class I cavities.[18]

In the current study, retention, color match, and marginal adaptation of both flowable materials have shown (alpha score) for all restorations at baseline and after 6 months, with no statistically significant difference between both groups.[7],[18] For marginal discoloration, at baseline alpha score for all restorations was observed in both groups. After 6 months, there was no marginal discoloration in Filtek Z350XT flowable, the functional monomer (10-MDP) formed stable complexes of calcium–phosphate salts with enhanced hydrolytic stability over time.[12] In Vertise Flow restorations, 15 restorations scored alpha after 6 months, clinically acceptable (bravo score) was observed in three restorations; there was no statistically significant difference between both materials after 6 months (P = 0.2278). The functional monomer GPDM dissolves gradually in moisture hence affecting the interfacial integrity as mentioned earlier.[13]

For postoperative hypersensitivity, at baseline in Filtek Z350XT flowable, 16 restorations scored alpha, two restorations revealed sensitivity; this may be attributed to etching with phosphoric acid which removed the smear layer, thus opening up the dentinal tubules; sensitivity decreased over time and completely disappeared at 6 months evaluation. No sensitivity was recorded for Vertise-Flow restorations at baseline or after 6 months. Vertise Flow dissolved the smear layer and did not remove it; thus, dentinal tubules were kept sealed. The results of postoperative hypersensitivity evaluation revealed no statistically significant differences between restorative materials at baseline (P = 0.4669) or after 6 months (P = 1.00).[6],[7]

 Conclusions



Under the limitations of the current study, the following conclusions could be derived:

SAFC has shown clinical performance similar to conventional flowable composite after 6 months of clinical service in conservative Class I cavity preparations.SAFC simplified the procedure of applying flowable composite material with comparable results to standard techniques.Flowable composite is a successful alternative for conventional composite in minimally invasive Class I cavities.

Clinical recommendations

Clinical studies are the last and the most important step to evaluate new materials and techniques; further, long-term clinical studies are required to confirm the results.Further investigations are also advised to assess whether the encouraging performance of the new material finds confirmation in other clinical applications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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