Highlights
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Controlled randomized prospective clinical split-mouth study on restoration of NCCLs in premolars with flowable composites.
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Three-year results of Filtek™ Supreme XTE Flow and N’Durance ® Dimer Flow for restoration of NCCLs employing FDI criteria.
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After three years, both flowable composites show similar clinical success rates (95.8%).
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Both flowable composites can be recommended for restoration of NCCLs.
Abstract
Objectives
To evaluate the clinical performance of two flowable composites for restoring Class-V non-carious cervical lesions (NCCLs), one with novel (ND; N’Durance ® Dimer Flow, Septodont) and one with modified conventional matrix composition (FS; Filtek™ Supreme XTE Flow, 3M-ESPE). The null hypothesis was that both flowable composites perform equally regarding clinical quality and survival.
Methods
50 patients received one ND and one FS restoration of NCCLs in premolars using Clearfil Protect Bond (Kuraray) as an adhesive. Restorations were evaluated by two examiners at baseline (BL), 18 and 36 months employing FDI criteria. Non-parametric statistical analyses and χ 2 tests were applied ( α = 0.05).
Results
48 patients with both restorations under risk participated in the 36-mo recall. One patient terminated participation after the 18-mo recall. One ND restoration failed at the 18-mo recall (fracture). One FS restoration failed during clinical examination at the 36-mo recall (debonding). 95.8% of restorations each were rated clinically acceptable at 36-mo. No significant differences for all selected FDI criteria were recorded between ND and FS at each examination time point except for the criteria surface staining at 36-mo and marginal staining at 18-mo and 36-mo, where FS showed significantly better results. For each material, no significant differences over time were detected, except for loss of surface lustre for FS (BL to 18 months).
Significance
Within the limitations of the study, the null hypothesis that materials perform equally could not be rejected. Both flowable composites performed equally regarding survival and similarly regarding clinical performance.
1
Introduction
Non-carious cervical lesions (NCCLs) are defined as loss of dental hard tissue at the cemento-enamel junction . The etiology of NCCLs is considered to be rather multifactorial with erosion, abrasion and abfraction (occlusal stress, tooth flexure) being main factors, conditioned by physical or chemical but not by microbiological processes . Their prevalence has been reported to vary between 5 and 85% with a strong tendency to increase with age . Therefore, considering the demographic change and an ageing population, the prevalence of NCCLs is likely to rise considerably in the future. NCCLs can affect tooth sensitivity, plaque retention, incidence of cervical caries and pulp vitality. Nonetheless, operative interventions in terms of restorative procedures should be carefully considered .
Currently, mainly methacrylate-based composites are used for restoration of NCCLs due to their esthetic and mechanical benefits as compared to glass ionomer cements . However, all current methacrylate-based composites exhibit a volumetric shrinkage during photo-polymerization creating stress, which is transmitted through the restoration upon the adhesive interfaces between tooth and restoration . Another drawback of conventional hybrid composites is the low ability of these materials to flex when the tooth structure is deformed under mechanical load due to their high elastic modulus . Consequently, the use of flowable composites has been proposed for restoration of NCCLs because of their considerably lower elastic modulus, suggesting that they may partly absorb the stress generated by shrinkage during polymerization and allow for the material to flex with the tooth during function . However, clinical studies failed to show a significant impact of differences in elastic moduli on retention rate . Meanwhile, flowable composites have become highly popular in general dental practice, in particular for minimally invasive restoration of NCCLs, due to their good rheological properties and their ease in handling , but also as a result of extended marketing efforts .
In general, the reduced viscosity in flowable composites is achieved by either reducing the filler content or by increasing the proportion of diluent monomers like triethylene glycol dimethacrylate (TEGDMA) in the composite paste . As a consequence, polymerization shrinkage is considerably raised since it is known that total shrinkage increases as the proportion of dimethacrylates increases . Therefore, creation of more stress on the adhesive interface is suggested , which may raise a concern about marginal sealing especially for restoration of larger NCCLs . To compensate for this drawback, in some novel flowable composites the conventional matrix composition is modified by substituting TEGDMA with high weight monomers with low viscosity, e.g. Procrylat (2,2-bis-4-(3-hydroxy-propoxy-phenyl)propane dimethacrylate) in Filtek™ Supreme XTE Flow (3M-ESPE, Seefeld, Germany).
Furthermore, recently composites with novel matrix technologies have been marketed, where conventional monomers like bisphenol A glycidyl methacrylate (bis-GMA), urethane dimethacrylate (UDMA) or TEGDMA are either partially or even completely replaced by new monomers . For example, dimer acid-based monomers have been introduced with higher molecular weights and lower initial double bond concentrations than conventional dimethacrylate monomers . These dimer acid-based monomers exhibit a higher degree of conversion, decreased volumetric shrinkage during polymerization due to phase separation and nearly negligible water sorption values in comparison with conventional monomers . Furthermore, dimethacrylates based on dimer acid lead to polymers with good flexibility and low elastic modulus due to their relatively low crosslink density . As a commercially available representative, N’Durance ® Dimer Flow (Septodont, Saint-Maur-des-Fossés, France) is a flowable nano-hybrid composite, which also has conventional monomers like bis-GMA, UDMA and dicarbamate included in its matrix composition . Consequently, especially for the restoration of NCCLs, this material may combine the benefits mentioned above, i.e. good handling due to flowable application as well as low polymerization shrinkage and low elastic modulus, thus potentially absorbing the stress generated by polymerization shrinkage to a greater extent and flexing with the tooth during mechanical load. However, since clinical data is scarce, only a well-controlled clinical trial can provide proof of clinical effectiveness.
Therefore, the aim of this randomized controlled clinical split-mouth study was to evaluate the three-year clinical performance of two flowable composites, one with novel (N’Durance ® Dimer Flow; ND) and one with modified conventional matrix composition (Filtek™ Supreme XTE Flow, 3M-ESPE, Seefeld, Germany; FS) for restoration of NCCLs (selected physical parameters for both materials are shown in Table 1 ). The null hypothesis was that the material with the new matrix technology (ND) providing lower polymerization shrinkage shows a clinical performance equal to the conventional material (FS).
| Parameter | Filtek™ Supreme XTE Flow (3M-ESPE, Seefeld, Germany) | N’Durance ® Dimer Flow (Septodont, Saint-Maur-des-Fossés, France) |
|---|---|---|
| Flexural strength [MPa] | 121 | 113 |
| Modulus of elasticity [GPa] | 6.8 | 5.3 |
| Compressive strength [MPa] | 318 | 258 |
| Volumetric shrinkage [vol.%] | 3.3 | 3.0 |
| Diametrial tensile strength [MPa] | 67 | 45 |
2
Material and methods
2.1
Study design
The present study is a three-year follow-up examination of a controlled randomized prospective clinical split-mouth study investigating the clinical performance of two flowable composites for restoration of NCCLs in premolars, one with modified conventional (FS) and one with novel matrix composition (ND) for reduction of polymerization shrinkage stress.
The study design followed the requirements outlined in the CONSORT 2010 statement and was approved by the Internal Review Board (IRB) of the University of Regensburg (IRB 11-101-0001) in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Written informed consent was obtained from all individual participants included in the study.
2.2
Patient selection
52 patients were recruited in a private practice by an experienced general dentist (S.M.) in the city of Amberg (Bavaria, Germany). Patients gave their informed consent after receiving a detailed description of the proposed treatments and agreed to participate in a six-month recall program for three years.
Patients (aged between 18 and 65 years) had to be in need for restorative treatment on at least two premolars with Class-V NCCLs because of dentine hypersensitivity or in order to prevent progression of these defects. For inclusion of the patient, the teeth to be restored had to be in different sites of the jaw without being direct antagonists, had to show positive sensitivity testing using the ice-spray test (Endo-Frost, Roeko/Coltene/Whaledent, Langenau, Germany) and tooth mobility had to be less than grade I (mobility of the tooth noticeable, but not visible). The papillary bleeding index (PBI) as described by Saxer and Mühlemann was employed as a measure of gingival inflammation and oral hygiene level. It had to be 30% or less. Exclusion criteria were patients suffering from serious medical disorders, severe or active periodontal diseases or carious lesions, poor oral hygiene (PBI > 30%) and intolerance or allergy towards the applied materials.
From the 52 patients initially recruited, 2 patients had to be excluded due to endodontic reasons. Therefore, restorative procedures were performed on 50 patients as described below.
2.3
Clinical restorative procedures
The restorative procedures were standardized and performed by one specially instructed and experienced general dentist (S.M.) in Amberg (Bavaria, Germany). Randomization of the restorations to either the control group (FS) or the experimental group (ND) was done following the coin-toss method. None of the restorations was placed with rubber dam isolation; moisture control and a dry operative field were accomplished using cotton rolls and a saliva ejector. The adjacent gingiva was retracted by retraction cords soaked in an aqueous aluminum chloride solution (0.22 g/ml; Mallebrin ® ; Krewel Meuselbach, Eitrof, Germany).
The tooth surface was cleaned with a slurry of pumice and rinsed with water spray in order to remove the salivary pellicle and any remaining biofilm. Sclerotic dentin was “surface-activated” using round carbide-burs whereby care was taken to remove as little dentin as possible. A short enamel bevel (≈1 mm) was prepared with fine grit (46 μm) diamond burs and water cooling. Cavities were disinfected using 0.2% chlorhexidine (Chlorhexamed ® FORTE 0.2% alkoholfrei, GlaxoSmithKline Consumer Health Care, Bühl Germany) and thoroughly rinsed with water spray.
Clearfil Protect Bond (Kuraray, Osaka, Japan; CPB) was used as an adhesive according to the instructions of the manufacturer. Primer was applied with a disposable brush tip, left in place for 20 s and dried with gentle air flow. Bond was applied with a disposable brush tip and air-flowed gently for creating a uniform bond film. Light-curing was carried out for 10 s with a LED light-curing unit (bluephase ® G2, Ivoclar-Vivadent, Schaan, Liechtenstein) in “low power” mode (irradiance of 650 mW/cm 2 as specified by the manufacturer).
Afterwards, either ND or FS were applied following instructions of the respective manufacturer in a standardized procedure: The restorations were placed in two to three increments depending on the size of the lesion and each increment was light-cured for 20 s (bluephase ® G2) in “low power” mode. After polymerization, restorations were finished using fine (46 μm) and ultra fine grit (25 μm) diamond burs (both: Komet Gebr. Brasseler, Lemgo, Germany), Arkansas stones (Acurata, Thurmansbang, Germany) and rubber points (Shofu, Kyoto, Japan; Komet Gebr. Brasseler, Lemgo, Germany). Subsequently, teeth were fluoridated (Bifluorid 12, VOCO, Cuxhaven, Germany).
2.4
Clinical examination
Clinical examination was performed by two blinded examiners, who had been calibrated in advance ( κ -values > 0.85) and who were not involved in the treatments and not aware of the restorative material used in the individual teeth or of earlier examination scores. The restorations were evaluated at baseline (BL; 1–2 weeks after restorative procedures) and thereafter every 6 months over a period of 3 years. The present study reports the results at BL and after 18 (18-mo) and 36 months (36-mo).
The FDI clinical criteria and scoring system was employed for evaluation of the restorations . The following criteria were selected for clinical characterization of the restorations:
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Esthetic properties
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surface lustre (A1)
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surface staining (A2a)
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marginal staining (A2b)
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Functional properties
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fracture of material and retention (B5)
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marginal adaptation (B6)
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Biological property
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postoperative hypersensitivity and tooth vitality (C11)
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The scale for assessment of FDI criteria is shown in Table 2 . Tooth vitality was investigated using the ice-spray test and postoperative hypersensitivities were determined by interview of the patients. The assessment of the investigation criteria was done by means of a five-score scale as shown in Table 2 . In case of any disagreement between the examiners after independent evaluation, consensus was reached by immediate joint reexamination of the restorations and discussion. The PBI according to Saxer and Mühlemann was employed to evaluate and document the patients’ gingival status and oral hygiene. Restorations were documented by digital photography preoperatively, at BL and at each respective recall appointment.
| Score | ||
|---|---|---|
| 1 | Clinically excellent/very good | Acceptable |
| 2 | Clinically good (after polishing or correction very good) | |
| 3 | Clinically sufficient/satisfactory (minor shortcomings with no unacceptable or adverse effects but not adjustable without damage to the tooth) | |
| 4 | Clinically unsatisfactory (but repairable or repair for prophylactic reasons) | Not acceptable |
| 5 | Clinically poor (replacement necessary) | |
2.5
Data analysis
For the evaluation of clinical changes over time and comparison of both flowable composites as documented by the FDI criteria, 48 patients with both restorations under risk were available for the 36-mo recall appointment.
The FDI BL data as well as the data for the 18-mo and 36-mo recall intervals are reported, referring to all pairs of restorations under risk until 36 months. The two flowable composites were compared to each other for every recall interval to detect differences between their clinical performances. Additionally, changes of clinical criteria over time between BL, 18-mo and 36-mo for all FDI criteria were evaluated for each material separately. For statistical analysis of the data χ 2 test was applied ( α = 0.05) using SPSS for Windows, version 20 (SPSS Inc., Chicago, IL, USA).
2
Material and methods
2.1
Study design
The present study is a three-year follow-up examination of a controlled randomized prospective clinical split-mouth study investigating the clinical performance of two flowable composites for restoration of NCCLs in premolars, one with modified conventional (FS) and one with novel matrix composition (ND) for reduction of polymerization shrinkage stress.
The study design followed the requirements outlined in the CONSORT 2010 statement and was approved by the Internal Review Board (IRB) of the University of Regensburg (IRB 11-101-0001) in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Written informed consent was obtained from all individual participants included in the study.
2.2
Patient selection
52 patients were recruited in a private practice by an experienced general dentist (S.M.) in the city of Amberg (Bavaria, Germany). Patients gave their informed consent after receiving a detailed description of the proposed treatments and agreed to participate in a six-month recall program for three years.
Patients (aged between 18 and 65 years) had to be in need for restorative treatment on at least two premolars with Class-V NCCLs because of dentine hypersensitivity or in order to prevent progression of these defects. For inclusion of the patient, the teeth to be restored had to be in different sites of the jaw without being direct antagonists, had to show positive sensitivity testing using the ice-spray test (Endo-Frost, Roeko/Coltene/Whaledent, Langenau, Germany) and tooth mobility had to be less than grade I (mobility of the tooth noticeable, but not visible). The papillary bleeding index (PBI) as described by Saxer and Mühlemann was employed as a measure of gingival inflammation and oral hygiene level. It had to be 30% or less. Exclusion criteria were patients suffering from serious medical disorders, severe or active periodontal diseases or carious lesions, poor oral hygiene (PBI > 30%) and intolerance or allergy towards the applied materials.
From the 52 patients initially recruited, 2 patients had to be excluded due to endodontic reasons. Therefore, restorative procedures were performed on 50 patients as described below.
2.3
Clinical restorative procedures
The restorative procedures were standardized and performed by one specially instructed and experienced general dentist (S.M.) in Amberg (Bavaria, Germany). Randomization of the restorations to either the control group (FS) or the experimental group (ND) was done following the coin-toss method. None of the restorations was placed with rubber dam isolation; moisture control and a dry operative field were accomplished using cotton rolls and a saliva ejector. The adjacent gingiva was retracted by retraction cords soaked in an aqueous aluminum chloride solution (0.22 g/ml; Mallebrin ® ; Krewel Meuselbach, Eitrof, Germany).
The tooth surface was cleaned with a slurry of pumice and rinsed with water spray in order to remove the salivary pellicle and any remaining biofilm. Sclerotic dentin was “surface-activated” using round carbide-burs whereby care was taken to remove as little dentin as possible. A short enamel bevel (≈1 mm) was prepared with fine grit (46 μm) diamond burs and water cooling. Cavities were disinfected using 0.2% chlorhexidine (Chlorhexamed ® FORTE 0.2% alkoholfrei, GlaxoSmithKline Consumer Health Care, Bühl Germany) and thoroughly rinsed with water spray.
Clearfil Protect Bond (Kuraray, Osaka, Japan; CPB) was used as an adhesive according to the instructions of the manufacturer. Primer was applied with a disposable brush tip, left in place for 20 s and dried with gentle air flow. Bond was applied with a disposable brush tip and air-flowed gently for creating a uniform bond film. Light-curing was carried out for 10 s with a LED light-curing unit (bluephase ® G2, Ivoclar-Vivadent, Schaan, Liechtenstein) in “low power” mode (irradiance of 650 mW/cm 2 as specified by the manufacturer).
Afterwards, either ND or FS were applied following instructions of the respective manufacturer in a standardized procedure: The restorations were placed in two to three increments depending on the size of the lesion and each increment was light-cured for 20 s (bluephase ® G2) in “low power” mode. After polymerization, restorations were finished using fine (46 μm) and ultra fine grit (25 μm) diamond burs (both: Komet Gebr. Brasseler, Lemgo, Germany), Arkansas stones (Acurata, Thurmansbang, Germany) and rubber points (Shofu, Kyoto, Japan; Komet Gebr. Brasseler, Lemgo, Germany). Subsequently, teeth were fluoridated (Bifluorid 12, VOCO, Cuxhaven, Germany).
2.4
Clinical examination
Clinical examination was performed by two blinded examiners, who had been calibrated in advance ( κ -values > 0.85) and who were not involved in the treatments and not aware of the restorative material used in the individual teeth or of earlier examination scores. The restorations were evaluated at baseline (BL; 1–2 weeks after restorative procedures) and thereafter every 6 months over a period of 3 years. The present study reports the results at BL and after 18 (18-mo) and 36 months (36-mo).
The FDI clinical criteria and scoring system was employed for evaluation of the restorations . The following criteria were selected for clinical characterization of the restorations:
- •
Esthetic properties
- ○
surface lustre (A1)
- ○
surface staining (A2a)
- ○
marginal staining (A2b)
- ○
- •
Functional properties
- ○
fracture of material and retention (B5)
- ○
marginal adaptation (B6)
- ○
- •
Biological property
- ○
postoperative hypersensitivity and tooth vitality (C11)
- ○
The scale for assessment of FDI criteria is shown in Table 2 . Tooth vitality was investigated using the ice-spray test and postoperative hypersensitivities were determined by interview of the patients. The assessment of the investigation criteria was done by means of a five-score scale as shown in Table 2 . In case of any disagreement between the examiners after independent evaluation, consensus was reached by immediate joint reexamination of the restorations and discussion. The PBI according to Saxer and Mühlemann was employed to evaluate and document the patients’ gingival status and oral hygiene. Restorations were documented by digital photography preoperatively, at BL and at each respective recall appointment.
