Twenty-Four-Month Clinical Comparison of Two Bulk-Fill and Microhybrid Composite Restorations
Phase: NA
Conditions: Dental Restoration Failure of Marginal Integrity
Sponsor: Tokat Gaziosmanpasa University

 
 
 
 
 
 
 
Document Date: 10March, 2020 
 
Twenty-Four-Month Clinical Comparison of Two Bulk-Fill and Microhybrid Composite Restorations 
 
Materials and Methods 
Patient selection 
The Research Ethics Committee of Tokat Gaziosmanpasa University (Tokat, Turkey) approved the study, and a 
group of patients who were seeking routine dental care was subsequently recruited by the Department of 
Restorative Dentistry, Faculty of Dentistry, Tokat Gaziosmanpasa University, and screened for inclusion in the 
study. A total of 25 patients who needed at least three similar Class II restorations were asked to participate in the 
study. 
The inclusion criteria were as follows: Patient in need of restoration of caries lesion (diagnosed with bitewing 
radiograph and clinical examination); teeth in need of restoration to be first or second molars or permanent 
premolars; at least three Class II restorations required in each patient and the number of restorations of each 
material to be equal in each patient; the antagonist and adjacent tooth in contact; pulp vitalized and free of painful 
symptoms; teeth involved not to have undergone direct pulp capping; no history of hypersensitivity in the teeth to 
be restored; permanent dentition; good oral health and absence of periodontal disease; patients not to have suffered 
from systemic diseases or allergies; and absence of deleterious habits, xerostomia, and bruxism. 
Specific exclusion criteria were as follows: Fewer than 20 teeth; history of existing tooth sensitivity; known allergy 
to resin-based materials or any of the other materials used in this study; pregnancy or breastfeeding; chronic use 
of anti‑inflammatory drugs, analgesic, and/or psychotropic drugs; non-vital teeth; abutment teeth for fixed or 
removable prostheses. The average age of patients was 20 years (range, 18–22 years). All patients participated 
voluntarily and were required to provide written informed consent. The purpose and implications of the treatment 
were discussed with the patients, and all participants consented to participate voluntarily in the study by signing a 
term of informed consent. The participants were informed that they were free to withdraw from the trial without 
justification at any stage of the research. 
The dental cavities were at least 3 mm deep. A bitewing radiograph of each tooth was taken using an X-ray device. 
The operator measured the height and depth of the proximal and occlusal cavity boxes with a periodontal probe 
(Satin Steel Handle; mm, Hu-Friedy, Chicago, IL, USA). One experienced dentist placed all 75 restorations. The 
filling materials and adhesives (Table 1), bulk fill materials [Sonic Fill (Kerr), x-tra fil (VOCO)] or microhybrid 
composite (Filtek Z-250 3M ESPE), were used according to the manufacturer’s instructions and were randomized 
over these two cavity groups by using a table of random numbers. Before treatment, initial periapical radiographs 
of the teeth to be treated were taken and vitality test scores were recorded. 
Restorative procedure 
All restorations (25 for each restorative material) were performed by the same operator to ensure consistency 
(M.B.). Twenty-five patients received a total of 75 restorations. As such, each patient received three Class II 
restorations randomly: one with Sonic Fill (Kerr); a conventional viscosity composite, Filtek Z-250 (3M ESPE); 

and the other with x-tra fil (VOCO), a high-viscosity bulk‑fill composite. Local anesthesia was applied for patients 
who complained of pain or sensitivity. The cavity preparation was made by using a spherical diamond bur 
(Meisinger Dental Burs, Hager and Meisinger GmbH, Neuss, Germany) on a high-speed air turbine. Infected 
dentin in the cavity was removed by carbide round burs used with a low-speed handpiece, and no bevel was 
prepared. Discolored but hard dentine was left in place at the cavity floor. The cavities were designed according 
to the principles of minimally invasive dentistry. None of the cavity preparations involved one or more cusps. All 
of the gingival margins included sound enamel. The operative field was cleaned with an air/water spray, gently 
air-dried, and then carefully isolated with cotton rolls and suction. The outline shape of the preparations was limited 
to the removal of caries; as such, no additional retention and bevel was prepared. For each restoration, the tooth 
type (molar/premolar) and cavity type (number of restored surfaces) were recorded. All patients received oral 
hygiene instructions and a professional tooth cleaning before initiating the restorative intervention. No liner or 
base was used.  
An ivory type matrix system (Hahnenkratt, Konigsbach-Stein, Germany) and wooden wedges were used. To 
remove water, the cavities were rinsed for 10 s and air-dried for 5 s. Three adhesive systems were used: 
OptiBond™ XTR (Kerr), Solobond M (VOCO), Adper Single Bond 2 (3M ESPE). The adhesives were applied 
following the manufacturer´s instructions (Table 1). All light-curing procedures were performed with the same 
LED-curing unit (Model BUILT-IN C, Guilin Woodpecker Medical Instrument Co., Ltd., Guilin, Guangxi, China) 
operating in a continuous mode while emitting a light-intensity of 1200 mW/cm2 according to the manufacturers’ 
recommended polymerization times. The light was directed perpendicular to the occlusal surface. 
Three different restorative resins were placed in each patient, resulting in a total of 75 restorations; 25 of the 
preparations were restored using the bulk-fill resin composite Sonic Fill (Kerr, Orange, CA, USA) (n = 25), 25 of 
them were restored with Filtek Z-250 (3M ESPE, St Paul, MN, USA) (n = 25), and 25 of them were restored with 
x-tra fil (VOCO, Cuxhaven, Germany), according to the manufacturers’ instructions (Table 1). The Filtek Z-250 
restorative material was applied using an incremental filling technique, beginning at the gingival wall. The 
increments, not exceeding 2 mm in thickness, were added to complete the proper anatomical form. Each increment 
was polymerized for 20 seconds. The x-tra fil restorative material was placed in bulk up to 4 mm in thickness and 
cured for 10 seconds with the same curing unit. The other bulk-fill resin composite material, Sonic Fill, was applied 
to the bonded cavities with sonication (SonicFill Handpiece, Kerr) and photo-polymerized for 40 s according to 
the manufacturer’s instructions. The randomization of restorative material was done using a table of random 
numbers. 
After removal of the matrix system, the restorations on the teeth in all groups were light-cured for a further 20 s 
from the buccal, lingual, and occlusal aspects. The cotton rolls were then removed, and occlusion and articulation 
were checked and adjusted. The surface of the teeth was finished with fine‑grit diamond instruments (Diatech, 
Coltene, Switzerland), polishing disks (Sof-Lex, 3M-ESPE, MN, USA), and rubber polishing instruments (One 
Gloss, Shofu, Kyoto, Japan). Water‑cooling was used throughout the finishing procedures. We used abrasive strips 
(3M ESPE, St. Paul, MN, USA) on the proximal surfaces when necessary. We checked the quality of the 
interproximal contact and the cervical adaptation by means of dental ﬂossing and bitewing radiographs. The 
clinical procedure of tooth preparation and placement of restorations was performed by the same operator. 
Periods and evaluation criteria 

One week after restoration placement (baseline), patients were recalled and restorations were examined clinically. 
Direct clinical evaluation of restorations was performed using the USPHS criteria (Table 2) by two independent 
investigators (E.S.K. and H.A.) using mirrors, probes, and bitewing radiographs and scored as Alpha, Bravo, or 
Charlie. Alpha corresponded to excellent, Bravo to clinically acceptable, and Charlie to clinically unacceptable 
results (Table 2). Patients were recalled at 6, 12, and 24 months for assessments of the restorations, using the same 
criteria as at baseline. At each recall, the same two calibrated evaluators, who were blinded to the restoratives used 
for cavities and patients, examined the restorations. To ensure a double-blind study, the evaluators were not 
informed about which filling material had been used on which teeth. When disagreement occurred during the 
evaluation, the final decision was made by the consensus of both examiners. All evaluations were carried out under 
a dental operating light, using ﬂat-surfaced mouth mirrors and dental explorers. Postoperative sensitivity was 
assessed by blowing a stream of compressed air for three seconds at a distance of 2 to 3 cm from the restoration 
under isolation from the adjacent teeth with gauze and by moving the probe over the restored tooth surface. 
The statistical analyses were carried out with the IBM SPSS version 22.0 software package (SPSS, Chicago, IL, 
USA). The restoration groups for each category were compared using the Pearson chi-square test, and the Cochran 
Q-test was used to compare the changes across different time points within each restorative material (p <0.05).