Abstract
Objective
The aim of this study was to evaluate the long-term clinical performance of a self-adhering flowable resin composite compared to a conventional flowable resin composite used with an etch&rinse adhesive system in minimally invasive Class I cavities.
Materials and Methods
Twenty-five patients received at least one pair of Class I restorations (n=65). After class I cavities had been prepared, they were randomly restored either with a self-adhering flowable resin composite (VertiseFlow/Kerr-VR) [Group-1 (n=33)], or with a flowable resin composite (Luxaflow/DMG-LX) in combination with an etch&rinse adhesive (Teco/DMG) [Group-2 (n=32)] according to the manufacturers' instructions. The restorations were evaluated at baseline and yearly during 5 years according to the FDI criteria by two evaluators. A statistical analysis was carried out using the Pearson Chi-Square test and the Cochran Q-test followed by the Mc Nemar's test (p=0.05).
Results
After 5 years a total of 47 restorations were evaluated with a recall rate of 68%. At 4-year, 3 (11.5%) VR and 2 LX (7.6%) restorations exhibited a cumulative retention loss. Seventeen (73.9%) VR and 14 LX (58.3%) restorations exhibited clinically acceptable (2) scores for marginal adaptation. At 5-year evaluations VR and LX showed similar results regarding all evaluated criteria (p > 0.05). The cumulative retention loss rates of VR and LX were 15.3% and 7.6%, respectively. None of the restorations demonstrated a recurrence of caries and post operative sensitivity. Both materials showed significant changes at 4 and 5 years regarding marginal staining when compared to baseline (p<0.001). Furthermore, significant changes were observed for VR and LX at 1, 2, 3, 4 and 5 years for marginal adaptation according to baseline (p<0.001).
Conclusion
The use of both materials for the restoration of Class-I cavities demonstrated clinically acceptable performance at the end of 5-year. The self-adhering flowable composite exhibited a clinical performance similar to the conventional flowable applied with an etch&rinse adhesive.
Key words: Dental Restoration, Permanent; Composite Resins; Adhesiveness; Dental Marginal Adaptation
Introduction
The occlusal morphology of pit and fissures is the main reason for development of dental caries at this region (1-3). Various restorative materials can be used clinically for the restoration of occlusal cavities clinically, e.g. glass ionomer cements, compomers and flowable composites (4, 5).
Flowable composite resins were first introduced in 1972 by Ibsen for the restoration of non-carious cervical lesions, and later these composite resins have found numerous application areas in dentistry such as Class II restorations and Class V cavities which are in need of stress relieving (6, 7). The applicability of flowable composite resins for Class I cavities has expanded with the development of these materials. Low viscosity, a low modulus of elasticity, and ease of handling are some of the desirable properties of flowable composite resins (8). The filler loading of flowable composite resins (weight: 60–70%; volume: 46–65%) is reduced compared to conventional hybrid composites (weight: 70–80%; volume: 60–75%) that are considered conventional composites (9, 10). This altered filler loading modifies the viscosity of flowable composites. In general, they are packed in small syringes which allow easy dispensing with very small gauge needles, thus allowing clinicians to use flowable composites in small preparations that would be difficult to fill otherwise (8). Flowable composites can be preferred on stress bearing occlusal surfaces. In addition, they offer different shade options to provide better esthetics (11). Therefore, flowable composites have traditionally been used for small Class I, II cavities and Class V lesions for years (8).
The application time of adhesive systems is variable. It is within the range of 36-115 seconds according to the manufacturer’s instructions. Besides, the number of clinical application steps is greater in etch- and- rinse systems compared to self-etch systems. In an attempt to reduce procedure steps, a self-adhering flowable composite (Vertise Flow, Kerr, Orange, USA) was introduced in the market. The advantage of the Vertise Flow over fissure sealants is its availability in nine different shades. Also, the Vertise Flow has shorter application time, and can be used in small class I restorations and as base/liner material for Class I and II restorations. Although the results of few clinical studies on the Vertise Flow were published (12, 13), long-term clinical results have not been published yet. Therefore, the aim of this study was to evaluate the 5-year clinical performance of self-adhering flowable composite compared to a conventional flowable composite using an etch and rinse adhesive system. The null hypothesis tested was that there would be no difference between the two flowable composite resins placed in minimally invasive Class I cavities.
Materials and Method
The experiment design followed the Consolidated Standards of Reporting Trials (CONSORT) statement (14). The ethical approval for the study was obtained by the Institutional Clinical Investigations Ethics Committee (Ethic No: HEK 11/40-12). All participants voluntarily participated in the study and were required to sign a written informed consent form.
Protocol Registration
This clinical trial was registered at ClinicalTrials.gov (NCT03556553).
Trial Design, Settings and Location of Data Collection
This was a double blind, randomized, and controlled clinical trial. The study was carried out in the clinic of Hacettepe University, School of Dentistry, Department of Restorative Dentistry.
Recruitment
Non-hospitalized patients were recruited in a group of as they were pursuing routine dental care.
Eligibility Criteria
A total of 63 participants were examined by two calibrated dentists to check if the participants met the inclusion and exclusion criteria (Figure 1). The examinations were performed using a mouth mirror and a periodontal probe. Twenty-five patients with a mean age of 20 (range 18-25) who met the inclusion and exclusion criteria were selected. They were collected from the Restorative Dentistry Department at Hacettepe University, Faculty of Dentistry. The inclusion criteria for patients were as follows: a) being 18 years or older, b) having no medical or behavioral problems preventing from attending review treatments, c) having at least 28 teeth. The exclusion criteria were: a) poor gingival health, b) uncontrolled, rampant caries, c) bruxism, d) removable partial dentures, e) xerostomia. Clinicians carried out the assessments macroscopically with a probe and a mouth mirror when detecting fissures in need of restorations. After radiological and clinical examinations, the vitality of teeth was checked, and only superficial occlusal caries were included in the study. The inclusion criteria for the restorations were as follows: 1) having natural or crowned tooth as antagonist teeth, 2) a caries lesion scored as 3 according to ICDAS II criteria, 3) confined to occlusal pits and fissures, 4) absence of previously placed restorations. The exclusion criteria for the teeth were: 1) non-vital or previous root canal therapy 2) pulpal pathology or periapical pathology, 3) near exposures of pulp chamber on preoperative radiographs.
Figure 1.
_10-21-f1.jpg)
Flow Diagram of the study. VR: Vertise Flow, LX: Luxa Flow, nP: number of patients, nR: number of restorations
Sample Size Calculation
Considering a 5% alpha and 90% power value, the minimum sample size was calculated as 30 per group.
Randomization
Sixty-five restorations were performed by two-experienced clinicians. Each patient received test materials according to a table of random numbers. The teeth were randomized for each of the two experimental conditions through a table of random numbers generated by the program "Research Randomized Program" (http://www.randomizer.org/form.htm). Clinicians performed a similar number of restorations for both groups (FDO: Vertise Flow [16], LuxaFlow [16], EE: Vertise Flow [17], LuxaFlow [16]).
Restorative Procedures
Before restorative procedures all fissures were cleaned using a rotating rubber cup adapted on a slow-speed handpiece, washed and dried, but not desiccated. The dimension of the preparation was determined by the size of the caries lesion. All included teeth had dental caries in fissure that had reached the dentin.
The materials used in the study are listed in Table 1. All teeth included in the study were molars. Cavities were prepared using diamond fissure burs (Diatech, Coltane/Whaledent AG, Altstaetten, Switzerland, 0211714) at high speed with water-cooling. The caries removal was completed using a round stainless steel bur (Edenta, Liechtenstein, D02.001) on a slow-speed hand piece. Local anesthesia was applied to patients complaining about pain or sensitivity to prevent discomfort during restorative procedures. Tissue removal was terminated when the dentin was hard on probing. The prepared cavities were then randomly restored with one of the restorative systems tested.
Table 1. The inclusion and exclusion criteria of participants.
| Inclusion criteria | Exclusion criteria |
|---|---|
|
a) being 18 years or older b) having no medical or behavioral problems preventing from attending review visits c) having at least 28 teeth |
a) poor gingival health b) uncontrolled, rampant caries c) bruxism d) removable partial dentures e) xerostomia. |
Vertise Flow (VR) (n=33): Cavity preparations were isolated by cotton rolls and Vertise Flow was placed to the entire cavity walls. A special brush of Vertise Flow was used to apply the composite with a moderate pressure for 15-20 seconds to obtain a thin layer (<0.5 mm). Excess material was removed with the brush if necessary. Subsequently, the lining was light-cured for 20 seconds with a light curing unit (Radii Plus, SDI, Victoria, Australia). After lining the cavity, the preparation was restored with 2 mm or less increments of Vertise Flow. Increments were light-cured for 20 seconds with a light curing unit.
Luxa Flow (LX) (n=32): After the cavity preparation was isolated by cotton rolls, enamel was etched for 30 seconds and dentin was etched with 37% phosphoric acid (Total Etch, Ivoclar Vivadent, Schaan, Liechtenstein) for 15 seconds. Then, acid was rinsed and the cavity preparation was gently dried with oil free air spray. After that, the adhesive (Teco, DMG, Hamburg, Germany) was applied to the surface using the applicator brush for 15 seconds. The adhesive was dried gently with oil free air and light-cured for 10 seconds. Afterwards, Luxa Flow was applied to the entire cavity with 2 mm or less increments and light-cured for 20 seconds.
The composite resins were carefully spread with a dental probe to prevent air entrapment. Light output of the curing unit was checked prior to application and ensured that it was 1200 mW/cm2. An articulating paper was used to check occlusion. Finishing and polishing were performed using fine-grit diamond burs (Diatech, Swiss Dental, Switzerland) and rubber cups (Kerr Corporation, Orange, CA, USA). A total number of 65 restorations were placed in 25 patients (10 male, 14 female).
Calibration for Clinical Evaluation
Before starting the evaluations, two experienced examiners other than the operators were trained for both intra-examiner and inter-examiner reliability. For this purpose, they observed 10 photographs that were representative of each score for each criterion. Measurements of percentage agreement between the examiners were at least 85%. In case of disagreement, a consensus was reached before the patients left.
Blinding
The examiners who were not involved in the restoration procedures and blinded to the group assignment performed the clinical evaluations. The subjects were also blinded to group assignment.
Clinical Evaluation
Patients were evaluated at baseline (one week after restoration placement) and, every year up to five years after placement. The restorations were checked for retention, marginal adaptation, marginal staining, surface luster, color match, recurrence of caries and postoperative sensitivity according FDI criteria. (15) The scores were ranked as follows: (1) Clinically excellent/very good, (2) Clinically good, (3) Clinically sufficient/satisfactory, (4) Clinically unsatisfactory and (5) Clinically poor. Two experienced and calibrated examiners who did not place the restorations and were completely blind to the study protocol made the evaluations at each recall, independently using mirrors, probes and air stream. Disagreements were solved during evaluations. The examiners had to reach a consensus before the participant was dismissed. New and empty evaluation forms were filled in by the examiners to remain blinded to group assignments at recalls.
The restoration retention rates were calculated using the following equation (16, 17): Cumulative failure %= [(PF+NF)/(PF+RR)] x 100%. PF is the number of previous failures before the current recall; NF is the number of new failures during the current recall and RR is the number of restorations recalled for the current recall.
Statistical Analysis
A statistical analysis followed the intention-to-treat protocol according to CONSORT (14). Statistical analyses were performed with the IBM SPSS version 22.0 software (SPSS, Chicago, IL, USA). The Pearson chi-square tests were used to compare two restorative materials and define frequency distributions of the evaluated criteria. The differences in the ratings of the two materials were tested after 1, 2, 3, 4, 5 years. The changes across different time points within each restorative material were analyzed by the Cochran Q-test followed by the Mc Nemar's tests. The level of significance was set at p < 0.05 for all tests.
Results
The recall rates were 96%, 80%, 76%, 72%, 68% for 1, 2, 3, 4 and 5-year evaluations, respectively. None of the restorations showed postoperative sensitivity and recurrence of caries at any evaluation (Table 2).
Table 2. Materials used in the study.
| Material /Manufacturer | Batch No | Composition | Application |
|---|---|---|---|
| Vertise Flow / Kerr, Orange, USA | 3413043 | GPDM adhesive monomer, UDMA, BisGMA, and other methacrylate comonomers, photoinitiators, fillers 70% by weight. Ytterbium Fluoride, barium aluminosilicate glass, prepolymerized fillers, and colloidal silica |
Dispense Vertise Flow in cavity with provided dispensing tip. Use provided brush to apply Vertise Flow to the entire cavity wall and beveled area with moderate pressure for 15-20 seconds to obtain a thin layer (<0.5 mm). Remove excess material around margins with the brush if necessary. Light cure for 20 seconds. After lining the cavity walls with Vertis Flow, build the restoration with more Vertise Flow in increments of 2 mm or less. Light cure each increment for 20 seconds |
| Luxa Flow / DMG, Hamburg, Germany | 620342 | Dental glass in an optimised matrix made of BIS-GMA, fillers 63 wt.% | Place l increments in 2mm or less. Light-cure for 20 seconds |
| UDMA: Urethanedimethacrylate, Bis-GMA: Bisphenol A diglycidylmethacrylate, GPDM:glycerophosphate dimethacrylate | |||
Overall retention
The retention rates were 100% for both materials at 1-year assessments. At 2-year recall 2 VR and 1 LX restorations were lost. No retention lost was detected at 3-year evaluations, but 1 VR and 1 LX restoration were lost at 4-year assessments. After 5 years the cumulative failure rates for retention were 15.3% (4 restorations) for VR and 7.6% (2 restorations) for LX group (Table 3) (p>0.05).
Table 3. Clinical evaluation outcomes of different restorations.
| Table 3. Clinical evaluation outcomes of different restorations | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Evaluation Criteria |
Score | Baseline n(%) | 1-year n(%) | 2-year n(%) | 3-year n(%) | 4-year n(%) | 5-year n(%) | |||||||
| VR (33) | LX (32) | VR (31) | LX (31) | VR (27) | LX (27) | VR (25) | LX (26) | VR (24) | LX (25) | VR (23) | LX (24) | |||
| Functional properties | Retention | 1 | 33 (100) |
32 (100) |
31 (100) |
31 (100) |
25 (92.6) |
26 (96.3) |
25 (100) |
26 (100) |
23 (95.8) |
24 (96) |
22 (95.6) |
24 (100) |
| 2 | ||||||||||||||
| 3 | ||||||||||||||
| 4 | ||||||||||||||
| 5 | 2 (7.4) |
1 (3.7) |
1 (4.2) |
1 (4) |
1 (4.3) |
|||||||||
| Marginal Adaptation |
1 | 33 (100) |
32 (100) |
18 (58.1) |
20 (62.5) |
8 (32.0) |
12 (46.2) |
9 (36.0) |
12 (46.2) |
6 (26.1) |
10 (41.7) |
6 (27.3) |
10 (41.7) |
|
| 2 | 13s (41.9) |
11s (37.5) |
16 s (64.0) |
14 s (53.8) |
16 s (64.0) |
14 s (53.8) |
17 s (73.9) |
14 s (58.3) |
16 s (72.7) |
14 s (58.3) |
||||
| 3 | ||||||||||||||
| 4 | ||||||||||||||
| 5 | 1 (4) |
|||||||||||||
| Esthetic properties | Marginal Staining | 1 | 33 (100) |
32 (100) |
25 (80.6) |
26 (83.9) |
16 (64.0) |
20 (76.9) |
16 (64.0) |
20 (76.9) |
14 (60.9) |
18 (75.0) |
14 (63.7) |
18 (75.0) |
| 2 | 5 (16.1) |
3 (9.7) |
9 (36.0) |
6 (23.1) |
9 (36.0) |
6 (23.1) |
9 s (39.1) |
6 s (25.0) |
8 s (36.3) |
6 s (25.0) |
||||
| 3 | ||||||||||||||
| 4 | ||||||||||||||
| 5 | 1 (3.2) |
2 (6.5) |
||||||||||||
| Surface Luster | 1 | 33 (100) |
32 (100) |
31 (100) |
29 (93.5) |
23 (92.0) |
24 (92.3) |
23 (92.0) |
24 (92.3) |
21 (91.3) |
22 (91.7) |
21 (95.5) |
22 (91.7) |
|
| 2 | 2 (6.5) |
2 (8.0) |
2 (7.7) |
2 (8.0) |
2 (7.7) |
2 (8.7) |
2 (8.3) |
1 (4.5) |
2 (8.3) |
|||||
| 3 | ||||||||||||||
| 4 | ||||||||||||||
| 5 | ||||||||||||||
| Color Match | 1 | 33 (100) |
32 (100) |
28 (90.3) |
28 (90.3) |
20 (80.0) |
23 (88.5) |
20 (80.0) |
23 (88.5) |
18 (78.3) |
21 (87.5) |
18 (81.8) |
21 (87.5) |
|
| 2 | 3 (9.7) |
3 (9.7) |
5 (20.0) |
3 (11.5) |
5 (20.0) |
3 (11.5) |
5s (21.7) |
3 (12.5) |
4s (18.2) |
3 (12.5) |
||||
| 3 | ||||||||||||||
| 4 | ||||||||||||||
| 5 | ||||||||||||||
| Biological properties | Postoperative Sensitivity | 1 | 33 (100) |
32 (100) |
31 (100) |
31 (100) |
25 (100) |
26 (100) |
25 (100) |
26 (100) |
23 (100) |
24 (100) |
22 (100) |
24 (100) |
| 2 | ||||||||||||||
| 3 | ||||||||||||||
| 4 | ||||||||||||||
| 5 | ||||||||||||||
| Recurrence of caries | 1 | 33 (100) |
32 (100) |
31 (100) |
31 (100) |
25 (100) |
26 (100) |
25 (100) |
26 (100) |
23 (100) |
24 (100) |
22 (100) |
24 (100) |
|
| 2 | ||||||||||||||
| 3 | ||||||||||||||
| 4 | ||||||||||||||
| 5 | ||||||||||||||
|
sIndicates significant difference in comparison with baseline according to Cochran’s Q test fallowed by McNemar's test (p<0.05) VR: Vertise Flow, LX: Luxa Flow. The outcomes were scored as follows: (1) clinically excellent/very good, (2) clinically good, (3) clinically sufficient/satisfactory, (4) clinically unsatisfactory, and (5) clinically poor. | ||||||||||||||
Marginal adaptation
At 1-year assessments, 13 VR (41.9%) and 11 LX (37.5%) restorations exhibited minor discrepancies which were scored as clinically good (2). At 2-year evaluations, 16 VR (64%) restorations and 14 LX (53.8%) restorations scored as clinically good (2) (p < 0.05) and only 1 VR restoration (3.8%) scored clinically poor (5). After 3 years 16 VR (64%) and 14 LX (53.8%) restorations scored as clinically good (2). At 4-year examinations, 17 VR (73.9) and 14 LX (53.8) showed clinically good (2) score. At the end of 5 years, 6 VR restorations (27.3%) and 10 LX (41.7%) restorations demonstrated clinically very good (1) scores, which was not statistically significant (p > 0.05).
Marginal staining
At 1-year evaluations, 5 VR (16.1%) and 3 LX (9.7%) the restorations demonstrated minor marginal staining which were scored as clinically good (2). One (3.2%) VR and 2 (6.5%) LX restorations scored as clinically poor (5). At 2-year examinations, 9 VR restorations (36%) and 6 LX (23.1%) restorations were scored as clinically good (2) (p > 0.05). At 3-year assessments, 9 VR (36%) restorations and 6 LX (23.1%) restorations were scored as clinically good (2). At the end of 5 years, 14 VR (63.7%) restorations and 18 LX (75%) restorations exhibited very good clinical (1) scores, which was not statistically significant (p < 0.05).
Surface luster
At 1-year examinations, all of VR restorations showed very good clinical (1) scores, however 2 LX (6.5%) restorations exhibited good clinical (2) scores. At 2-year evaluations, 2 VR (7.7%) restorations and 2 LX (8%) were restorations scored as clinically good (2). After 4 years, most of the restorations [VR: 91.3%, LX: 91.7%] in both groups exhibited very good clinical scores (1). At the end of 5 years, 1 VR (4.5%) restoration and 2 LX (8.3%) restorations demonstrated good clinical (2) scores, whereas the rest of the restorations were excellent (score 1) for the criteria assessed. No significant difference was detected for surface luster at any time interval (p > 0.05) (Table 4).
Table 4. Relative cumulative frequencies (%) of lost restorations during 60-month follow-up.
| 2-year | 3-year | 4-year | 5-year | |
|---|---|---|---|---|
| Vertise Flow | 7.4 | 7.4 | 11.5 | 15.3 |
| LuxaFlow | 3.7 | 3.7 | 7.6 | 7.6 |
| No significant difference were observed between groups when compared to baseline according to Cochran’s Q test (p < 0.05). | ||||
Color match
Three VR and 3 LX restorations scored as clinically good (2) at 1-year [VR: 9.7%, LX: 9.7%]. At 2-year assessments, 5 VR (20%) and 3 LX (11.5%) scored as clinically good (2). At the end of 5 years, 4 VR (18.2) and 3 LX (12.5%) restorations scored as clinically good (2) and the differences were not statistically significant (p > 0.05).
The McNemar’s test showed a significant change in marginal adaptation in VR and LX groups at all evaluated points (1, 2, 3, 4, 5-year) compared to baseline (p < 0.001). Besides, both materials showed significant changes starting from 4-year regarding marginal staining (p < 0.001). The color match of VR exhibited significant changes after 4 and 5-year evaluations compared to baseline. (p < 0.001).
Discussion
Clinical trials conducted with minimal occlusal restorations mostly involve children. In this case, the application becomes harder to perform and a good enamel bonding is crucial for these restorations to survive. Besides, the parents have to be willing to bring their children for follow-up and cooperation can be difficult to achieve. In the present study, the participants older than 18 were selected, hence the cooperation and follow-up were easier to achieve. The recall rate was 68% and the follow-up was considered acceptable after 5 years.
Vertise Flow was manufactured to combine a self-etch system to the flowable composite. The bonding mechanism is a chemical bonding produced via glycerophosphate dimethacrylate (GPDM) between phosphate functional groups of GPDM monomers and calcium ions of enamel and dentin (18). To reduce steps at restorative applications, the formulation of this self-adhering composite resin was developed as the combination of prime, bond and composite resin. The elimination of multiple steps is required for easy application and short application time, particularly in young patients with behavioral problems and children.
An in vitro study (13) showed that Vertise Flow resulted in lower bond strength values when compared with all-in-one adhesive systems. However, the first clinical study published (19) regarding Vertise Flow suggested that after 6-month, the Vertise Flow exhibited acceptable results and no retention loss was reported. Similarly, the present study showed no retention loss at 1-year examination. However, after 5 years, 5 restorations lost retention (15.3%). Kucukyılmaz et. al. (12) compared Vertise Flow with two types of fissure sealants and a flowable composite with an adhesive system. The flowable composite used with an adhesive system exhibited higher retention rates (95.7%) than other sealing materials. The retention rate of Vertise Flow was the lowest (62.9%) after 2-year evaluation. Conversely, in the present study, it was found that the conventionally applied flowable composite resin LuxaFlow with an etch&rinse system showed similar results to Vertise Flow. Therefore, the null hypothesis was accepted.
In this study the FDI evaluation criteria were used since they are more sensitive to small variations in the clinical outcomes compared with the USPHS criteria. (15) Minor differences are scored differently from excellent restorations. This might explain the high (2) scores regarding marginal adaptation and marginal discoloration of both groups after 5-year assessments. Kitasako et al. (20) evaluated two different type of flowable composite resins placed using a two-step self-etch adhesive with FDI criteria, and concluded that tested groups had similar clinical outcome at 3-year follow-up.
The addition of a self-etch adhesive to the composite resin might have adverse effects on physical properties of the flowable composite resin. Hydrophilic monomers in the self-adhering restorative material can be the reason for unstable dimensions of composite resin (21). The filler content of Vertise Flow (wt 70%) and LuxaFlow (wt 63%) by weight is similar according to manufacturers, therefore mechanical and physical behaviors are expected to be similar. Clinical trials conducted using self-etch adhesives have demonstrated that their long-term stability is questionable compared to etch&rinse adhesive systems (22-24). However, the result of this clinical investigation showed similar outcomes considering the properties of the restorative materials. Flowable composites are thought to have greater polymerization shrinkage than conventional packable composites (25). Consequently, an increased rate for marginal discoloration, marginal adaptation and secondary caries is expected. However, a clinical study reported that, after two years, a flowable composite showed the results that were similar to a conventional composite (26). In the present study, after 5 years, the flowable composites exhibited similar results. Consequently, it could be speculated that the stress between the composite and the tooth is not sufficient to separate the restoration. Furthermore, lower modulus of elasticity might result in reduced stress at the adhesive interface (6, 27). Although it is possible that marginal gaps get wider over some time, a study has demonstrated that in a wet environment polymerization stresses may relax over time (28).
The acidity of self-etch adhesives varies and pH might have an effect on clinical performances. A systematic review (29) on the clinical performance of adhesives suggested that mild two-step self-etch adhesives showed the best clinical bonding effectiveness. On the other hand, strong self-etch (pH<1.5) and two-step etch-and-rinse adhesives were shown to exhibit unfavorable results. Vertise Flow has a pH level of 1.9, which is classified as mild, (30) but no significant difference was detected between two restorative materials clinically. The adhesive system used in the LuxaFlow group (Teco) is an acetone free adhesive. Also, Vertise Flow was used with the Optibond self-etch technology according to the manufacturer’s instructions, which is an ethanol, based adhesive system. Although etch&rinse adhesives are expected to have superior results than self-etch systems (22, 23), in the present study, Vertise Flow and LuxaFlow exhibited similar clinical outcomes after 5 years. However, Sabbagh et al. (31) showed that Vertise Flow and Premise Flowable used with a self-adhesive resin system exhibited similar clinical findings and both groups demonstrated a decrease in alpha scores over time. Some previous clinical trials (12, 32) had compared flowable composites to fissure sealants at pit and fissures and reported to have superior clinical results. In the present study, the self-adhering flowable composite obtained the results which were similar to a flowable composite when applied by the use of an etch&rinse adhesive.
The penetration of the flowable composite resins is another important factor for success. An in vitro study reported that enamel etching enhanced the penetration capacity of self-adhesive composites and recommended selective etching before Vertise Flow. (33) Kucukyilmaz et al. (12) reported that Vertise Flow demonstrated satisfactory results after 24-month. They mentioned that out of 40 Vertise Flow restorations, only two showed Bravo scores and one Charlie score for marginal discoloration and integrity.
One year or two years are short periods to evaluate the clinical performance of dental restorative materials. Long-term clinical studies are needed to validate these findings. The choice of restorative material for superficial Class I cavities should be determined by the long-term performance of composite resins. Therefore, the restoration of superficial Class I cavities with flowable composite resins must be carefully and continuously reviewed by periodic follow-ups to detect failures and obtain more reliable results.
Conclusion
Within the limitations of this clinical trial, it can be concluded that the self-adhering flowable (Vertise Flow) and the conventional flowable composite resin used with an etch&rinse system have similar clinical performance at 5-year follow-up period. Both materials showed some degradation over time regarding marginal adaptation and marginal discoloration.
Acknowledgments
Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent: Informed consent was obtained from all individual participants included in the study.
Footnotes
Conflict of interest: The authors declare no conflict of interest.
Funding: No funding
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