Posterior bulk-filled resin composite restorations: A 5-year randomized controlled clinical study

Abstract

Objective

To evaluate in a randomized controlled study the 5-year clinical durability of a flowable resin composite bulk-fill technique in Class I and Class II restorations.

Material and methods

38 pairs Class I and 62 pairs Class II restorations were placed in 44 male and 42 female (mean age 52.4 years). Each patient received at least two, as similar as possible, extended Class I or Class II restorations. In all cavities, a 1-step self-etch adhesive (Xeno V+) was applied. Randomized, one of the cavities of each pair received the flowable bulk-filled resin composite (SDR), in increments up to 4 mm as needed to fill the cavity 2 mm short of the occlusal cavosurface. The occlusal part was completed with the nano-hybrid resin composite (Ceram X mono+). In the other cavity, the resin composite-only (Ceram X mono+) was placed in 2 mm increments. The restorations were evaluated using slightly modified USPHS criteria at baseline and then yearly during 5 years. Caries risk and bruxing habits of the participants were estimated.

Results

No post-operative sensitivity was reported. At 5-year 183, 68 Class I and 115 Class II, restorations were evaluated. Ten restorations failed (5.5%), all Class II, 4 SDR-CeramX mono+ and 6 CeramX mono+-only restorations. The main reasons for failure were tooth fracture (6) and secondary caries (4). The annual failure rate (AFR) for all restorations (Class I and II) was for the bulk-filled-1.1% and for the resin composite-only restorations 1.3% (p = 0.12). For the Class II restorations, the AFR was 1.4% and 2.1%, respectively.

Conclusion

The stress decreasing flowable bulk-fill resin composite technique showed good durability during the 5-year follow-up.

Clinical significance

The use of a 4 mm incremental technique with the flowable bulk-fill resin composite showed during the 5-year follow up slightly better, but not statistical significant, durability compared to the conventional 2 mm layering technique in posterior resin composite restorations.

Introduction

In many countries, resin composites have been used increasingly in posterior teeth after the ban of amalgam in these countries. Developments during the years in chemical composition, filler reinforcement and adhesive techniques have resulted in many new or modified categories of materials. It has been stated that the polymerization of the resin matrix may challenge the stability of the restoration. Depending on the concentration, the type and the flexibility of the reacting groups, polymerization shrinkage is manifested as different degrees of shrinkage stress when monomer molecules are converted into a polymer network. The shrinkage stress may result in marginal deficiencies, enamel fractures, cuspal movements and cracked cusps, which in their turn may give microleakage, post-operative sensitivity and secondary caries . Different restorative techniques and resin composites have been used during the years to minimize the shrinkage stress . The clinical evidence that these can improve clinical effectiveness is, however, weak . Aside from the material properties, influence of the operator and patient factors play an important role determining the clinical durability of the resin-based restorations. Traditionally, resin composites have been placed in increments of 2 mm by an horizontal or oblique incremental layering technique, to ensure optimal light penetration and conversion. A recent development in resin composite technology is the introduction of a group of products introduced as the so-called “bulk-fill resin composites” . This group of materials include both low– and high viscosity materials, which have in common that they can be cured in up to 4 mm layers. The low viscosity materials have to be covered with an occlusal layer of conventional hybrid resin composite, which is not necessary for the high viscous materials. Concern about the mechanical stability in stress-bearing restorations of bulk-fill resin composites and absence of long-term clinical studies may discourage the clinicians to use the technique. Despite numerous in vitro publications, the clinical evidence of the modified layering technique is almost totally missing. So far, only for the first marketed flowable bulk-fill resin composite (SDR; Dentsply DeTrey), 3-year results have been reported in a randomized clinical evaluation . For none of the other products in the bulk-fill resin composite group there has been published clinical evidence.

The aim of this randomized controlled study was to further investigate, in large and deep Class I and Class II cavities, the 5-year durability of the flowable bulk fil resin composite SDR. In a intraindividual comparison the bulk-fill restoration was compared with a nano-hybrid resin composite-only restoration placed and cured with a 2 mm layering technique. The null hypothesis tested was that there would be no differences in clinical durability between restorations placed with the bulk-fill technique and those without.

Material and methods

During October–December 2010, all adult patients attending the Public Dental Health Service clinic at the Dental School Umeå and a private dental clinic in Copenhagen, who needed one or two pair similar Class I or Class II restorations, were asked to participate in the follow up. All patients invited, participated in the study. No participant was excluded because of high caries activity, periodontal condition or parafunctional habits in order to mirror the whole patient population. All patients were informed on the background of the study, which was approved by the ethics committee of the University of Umeå (Dnr 07–152 M) and followed recent CONSORT and FDI recommendations. Reasons for placement of the resin composite restorations were primary and secondary carious lesions, fracture of old fillings or replacement because of aesthetic or other reasons. In order to make an intra-individual comparison possible, each patient received two or four as similar sized and located restorations as possible. The majority of the cavities were deep and had extended sizes. There was no limitation in the thickness of the remaining cusps. The cavity pairs in each individual were after cavity preparation randomly distributed to be restored with either the experimental or the control restoration according to a predetermined scheme of randomization. The participants were not aware in which cavity, the experimental and control restoration were placed. In the deepest part of the experimental cavity an intermediate of the SDR flowable RC (Dentsply/DeTrey, Konstanz, Germany; Table 1 ) was placed in layers of 4 mm. The flowable resin composite was covered with a 2 mm occlusal layer of the nano-hybrid resin composite Ceram X mono+ (Dentsply/DeTrey; from now on called Ceram X). The control restoration was filled incrementally with 2 mm layers of Ceram X (resin composite-only restoration). All teeth were in occlusion and had at least one proximal contact with an adjacent tooth. Thirty-eight pairs Class I and 62 pairs Class II restorations were placed in 82 patients (44 men, 42 women) with a mean age of 52.4 years (20–86). The distribution of the involved experimental teeth is shown in Table 2 . The sample size was calculated on the basis of previous sample size calculations performed in similar designed studies of posterior restoration evaluations. The theoretical sample size was set to 40 restorations per group to determine significant differences in outcomes at the 95% confidence level, with an alpha value = 0.05 and 80% power . Significant differences between material groups in similar intraindividual comparison design evaluations have been possible to determine with this sample size . The number of participants was increased to safeguard for possible drop outs.

Table 1
Resin composites and adhesive system used.
Material Composition Type Application steps Manufacturer
SDR Filler: Barium-alumino-fluoro-borosilicate glass, strontium alumino-fluoro-silicate glass. Filler content: w:68%, v:45%
Matrix: modified urethane dimethacrylate resin, ethoxylated bisphenol-A dimethacrylate (EBPADMA), triethyleneglycol dimethacrylate, camphorquinone, butylated hydroxyl toluene, uv stabilizer, titanium oxide,iron oxide pigments. The SDR flow base is covered with at least 2 mm RC.
4 mm layers, light cured 20 s Dentsply DeTrey, Konstanz, Germany
Ceram X
mono +
Filler: Barium-aluminium-borosilicate glass (1.1–1.5 μm), methacrylate functionalized silicone dioxide nano filler (10 nm). Filler content w:76%, v:57%
Matrix: Methacrylate modified polysiloxane, dimethacrylate resin, ethyl-4-(dimethylamino)benzoate, fluorescent pigment, UV stabilizer, stabilizer, camphorquinone, titanium oxide pigments, aluminium silicate pigments
nanohybrid
76% w/w filler
57% v/v filler average size nanofillers 10 nm and nano particles 2.3 nm
2 mm layers, light cured 20–30 s Dentsply DeTrey,
Xeno V+ 1-component one-step
self-etching adhesive
apply primer 20 s,
careful air drying for >5 s, light cured 10s.
Dentsply DeTrey

Table 2
Distribution of the experimental restorations.
Surfaces Mandibula Maxilla
Premolars Molars Premolars Molars
Class I 2 25 13 36 76
Class II 33 40 19 32 124
35 65 32 68 200

Clinical procedure

The clinical procedure has been described earlier . Existing restorations and/or caries were removed under constant water cooling. No bevels were prepared. The operative field was carefully isolated with cotton rolls and suction device. For all Class II cavities a thin metallic matrix was used and carefully wedging was performed with wooden wedges (Kerr/Hawe Neos, Switzerland). The cavities were cleaned by thoroughly rinsing with water. In none of the cavities Ca(OH) 2 or other base materials was applied. Application of the 1-step self etching adhesive XenoV+ (DeTrey Dentsply) in both cavities was performed according to the manufacturers instructions ( Table 1 ). After 20 s gently agitating, the solvent was evaporated thoroughly during at least 5s. Curing was then performed with a well controlled high power curing unit (Smartlite PS, Dentsply/DeTrey) for at least 10s. In the SDR cavity, the flow material was dispensed directly into the cavity from the compula tip using slow steady pressure, starting dispensing at the deepest portion of the cavity, keeping the tip close to the cavity floor. The tip was gradually withdrawn as the cavity was filled. The material was available in one semi-transluscent universal shade. It was placed in bulk increments up to 4 mm as needed to fill the cavity 2 mm short of the occlusal cavosurface. After curing of the flow increment(s)(20s), the occlusal part of the restoration was completed using the Ceram X resin composite material. In the control cavity the resin composite Ceram X was applied in 2 mm layers with, if possible, an oblique layering technique. Selected resin composite instruments (Hu-Friedy Mfg. Co., Chicago, Ill,USA) were used. The pairs of restorations with each of the two restorative combinations were placed by two experienced operators (JvD, UP). After checking the occlusion/articulation and contouring with finishing diamond burs, the final polishing was performed with the Shofu polishing system (Brownie; Shofy Dental Cooperation, Kyota, Japan) and finishing strips (GC finishing strips, Tokyo, Japan).

Evaluation

At baseline (after placement of the restorations) and than yearly during the whole follow up, the restorations were assessed by the following parameters: anatomic form, marginal adaptation, marginal discoloration, surface roughness, color match and secondary caries by slightly modified USPHS criteria according to van Dijken 1986 ( Table 3 ) . The follow up registrations were performed blindly by both operators at their clinics and at regular intervals by two calibrated evaluators. During the evaluation sessions, evaluators did not know which restorative material group the scoring concerned. The participants were asked at the next visit and all recalls if they had experienced symptoms in the region of the experimental teeth The caries risk for each participant and their parafunctional habits activity at baseline and during the follow ups was estimated by the treating clinician by means of clinical and socio-demographic information routinely available at the annual clinical examinations, e.g. incipient caries lesions, former caries history, frequency, dietary habits, oral hygien, medications, salivary properties and symptoms related to bruxing activity .

Table 3
Modified USPHS criteria for direct clinical evaluation (modified after van Dijken 1986).
Category Score (acceptable/unacceptable) Criteria
Anatomical form 0 The restoration is contiguous with tooth anatomy
1 Slightly under- or over-contoured restoration; marginal ridges slightly undercontoured; contact slightly open (may be self-correcting); occlusal height reduced locally
2 Restoration is undercontoured, dentin or base exposed; contact is faulty, not self-correcting; occlusal height reduced; occlusion affected
3 Restoration is missing partially or totally; fracture of tooth structure; shows traumatic occlusion; restoration causes pain in tooth or adjacent tissue
Marginal adaptation 0 Restoration is contiguous with existing anatomic form, explorer does not catch
1 Explorer catches, no crevice is visible into which explorer will penetrate
2 Crevice at margin, enamel exposed
3 Obvious crevice at margin, dentin or base exposed
4 restoration mobile, fractured or missing
Color match 0 Very good color match
1 Good color match
2 Slight mismatch in color, shade or translucency
3 Obvious mismatch, outside the normal range
4 Gross mismatch
Marginal discoloration 0 No discoloration evident
1 Slight staining, can be polished away
2 Obvious staining can not be polished away
3 Gross staining
Surface roughness 0 Smooth surface
1 Slightly rough or pitted
2 Rough, cannot be refinished
3 Surface deeply pitted, irregular grooves
Caries 0 No evidence of caries contiguous with the margin of the restoration
1 Caries is evident contiguous with the margin of the restoration

Statistical analysis

The characteristics of the restorations are described by descriptive statistics using cumulative frequency distributions of the scores. The experimental and control restorative techniques were compared intra-individually with the non parametric Friedmańs two-way analysis of variance test .

Material and methods

During October–December 2010, all adult patients attending the Public Dental Health Service clinic at the Dental School Umeå and a private dental clinic in Copenhagen, who needed one or two pair similar Class I or Class II restorations, were asked to participate in the follow up. All patients invited, participated in the study. No participant was excluded because of high caries activity, periodontal condition or parafunctional habits in order to mirror the whole patient population. All patients were informed on the background of the study, which was approved by the ethics committee of the University of Umeå (Dnr 07–152 M) and followed recent CONSORT and FDI recommendations. Reasons for placement of the resin composite restorations were primary and secondary carious lesions, fracture of old fillings or replacement because of aesthetic or other reasons. In order to make an intra-individual comparison possible, each patient received two or four as similar sized and located restorations as possible. The majority of the cavities were deep and had extended sizes. There was no limitation in the thickness of the remaining cusps. The cavity pairs in each individual were after cavity preparation randomly distributed to be restored with either the experimental or the control restoration according to a predetermined scheme of randomization. The participants were not aware in which cavity, the experimental and control restoration were placed. In the deepest part of the experimental cavity an intermediate of the SDR flowable RC (Dentsply/DeTrey, Konstanz, Germany; Table 1 ) was placed in layers of 4 mm. The flowable resin composite was covered with a 2 mm occlusal layer of the nano-hybrid resin composite Ceram X mono+ (Dentsply/DeTrey; from now on called Ceram X). The control restoration was filled incrementally with 2 mm layers of Ceram X (resin composite-only restoration). All teeth were in occlusion and had at least one proximal contact with an adjacent tooth. Thirty-eight pairs Class I and 62 pairs Class II restorations were placed in 82 patients (44 men, 42 women) with a mean age of 52.4 years (20–86). The distribution of the involved experimental teeth is shown in Table 2 . The sample size was calculated on the basis of previous sample size calculations performed in similar designed studies of posterior restoration evaluations. The theoretical sample size was set to 40 restorations per group to determine significant differences in outcomes at the 95% confidence level, with an alpha value = 0.05 and 80% power . Significant differences between material groups in similar intraindividual comparison design evaluations have been possible to determine with this sample size . The number of participants was increased to safeguard for possible drop outs.

Table 1
Resin composites and adhesive system used.
Material Composition Type Application steps Manufacturer
SDR Filler: Barium-alumino-fluoro-borosilicate glass, strontium alumino-fluoro-silicate glass. Filler content: w:68%, v:45%
Matrix: modified urethane dimethacrylate resin, ethoxylated bisphenol-A dimethacrylate (EBPADMA), triethyleneglycol dimethacrylate, camphorquinone, butylated hydroxyl toluene, uv stabilizer, titanium oxide,iron oxide pigments. The SDR flow base is covered with at least 2 mm RC.
4 mm layers, light cured 20 s Dentsply DeTrey, Konstanz, Germany
Ceram X
mono +
Filler: Barium-aluminium-borosilicate glass (1.1–1.5 μm), methacrylate functionalized silicone dioxide nano filler (10 nm). Filler content w:76%, v:57%
Matrix: Methacrylate modified polysiloxane, dimethacrylate resin, ethyl-4-(dimethylamino)benzoate, fluorescent pigment, UV stabilizer, stabilizer, camphorquinone, titanium oxide pigments, aluminium silicate pigments
nanohybrid
76% w/w filler
57% v/v filler average size nanofillers 10 nm and nano particles 2.3 nm
2 mm layers, light cured 20–30 s Dentsply DeTrey,
Xeno V+ 1-component one-step
self-etching adhesive
apply primer 20 s,
careful air drying for >5 s, light cured 10s.
Dentsply DeTrey
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Jun 19, 2018 | Posted by in General Dentistry | Comments Off on Posterior bulk-filled resin composite restorations: A 5-year randomized controlled clinical study
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