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  1. Recent advances in resin based adhesives and restorative materials together with the improvements in formulation and simplification of the adhesive procedures have…
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  • 1. Recent advances in resin based adhesives and restorative materials together with the improvements in formulation and simplification of the adhesive procedures have stimu- lated an increase in the use of resin based composites in the posterior region.3,5 Direct posterior resin restorations con- tinue to become more and more popular as functional, es- thetic alternatives to amalgam.25 Adhesively bonded resin composites have the advantage of conserving tooth structure with the potential for tooth reinforcement, while at the same time providing a cosmetically acceptable restoration.11 During the last decade, new formulations have been pre- sented; the average filler size was reduced drastically, and altered size distribution of submicrometer filler particles were used to optimize the filler load in order to improve the mechanical and wear characteristics.6 However, no one com- posite material has been able to meet both the functional needs of a posterior Class I or II restoration and the superior esthetics required for anterior restorations.8 The revolutionary development of nanotechnology has gained great interest in dentistry, as well as in the other fields of science and medicine. Nanotechnology is based on the production of functional materials and structures in the range of 1 to 100 nanometers using various physical and chemical methods. One of the most distinguished and sig- nificant contributions of this technology to dentistry has been the development of resin-based composite materials. In nanotechnology, some particles are produced using a Clinical Performance of Novel Resin Composites in Posterior Teeth: 18-Month Results Zeynep Ergücüa/L. Sebnem Türkünb Purpose: The aim of this study was to evaluate the clinical success potential of two nanocomposites placed in poste- rior teeth using an antibacterial adhesive system over 18 months. Methods: A total of 49 Class I and 47 Class II restorations were placed in the permanent teeth of thirty adult pa- tients. The carious lesions were restored with Grandio (Voco) or Filtek Supreme (3M ESPE) using a two-step self-etch- ing antibacterial adhesive system Clearfil Protect Bond (Kuraray). The restorations were finished with fine-grit diamond burs, Enhance polishing system, and Sof-Lex finishing brushes. The restorations were evaluated at baseline, 6, 12, and 18 months after placement using modified Ryge criteria for color stability, marginal discoloration, marginal adaptation, caries formation, anatomic form, postoperative sensitivity, surface roughness, and retention. Results: The changes in the parameters were assessed using the Cochran Q test and the McNemar test at a signifi- cance level of p < 0.05. All restorations were classified as clinically satisfactory after 18 months. Statistical analysis demonstrated differences only in superficial roughness, with Grandio exhibiting more surface roughness than Filtek Supreme (p < 0.05). Conclusion: Posterior restorations built up with the novel nanocomposites using an antibacterial self-etching system showed satisfactory results at the 18-month recall appointment relative to all criteria except the surface texture in the case of Grandio. Further evaluations are necessary for a more in-depth analysis. Keywords: nanofill, nanohybrid, antibacterial adhesive, posterior restorations. J Adhes Dent 2007; 9: xx-xx. Submitted for publication: 02.05.06; accepted for publication: 13.09.06. Vol 9, No 2, 2007 209 a Assistant Professor, Ege University School of Dentistry, Department of Restorative Dentistry, Izmir, Turkey. b Associate Professor, Ege University School of Dentistry, Department of Restorative Dentistry, Izmir, Turkey. Reprint requests: Dr. Zeynep Ergücü, Ege University School of Dentistry, De- partment of Restorative Dentistry, 35100 Izmir, Turkey. Tel: +90-232-388-03- 28, Fax: +90-232-388-03-25. e-mail: zergucu@yahoo.com This study, with its 12-month results, was presented at the Joint Meeting of the CED/NOF of the IADR, 14-17 September 2005, Amsterdam, the Netherlands.
  • 2. new technique, and grit size is no longer determined by sim- ple milling. The milling procedures usually cannot reduce the filler particle size below 100 nm. To circumvent this barrier, the particles are created from different components using Sol-gel chemistry.24 Currently, there is a conflict in the terminology used to de- fine the resin composites that contain nanoparticles. In re- cent studies, the terms “nanofilled”, “nanohybrid,” or “nano- structured” were used by various authors in order to classi- fy the type of some resin composites.4,2,35 Therefore, to avoid confusion, these novel materials are named nanocom- posites in this study. Nanocomposites combine the esthetic properties required for cosmetic restorations and the me- chanical properties necessary for posterior restorations. Due to the reduced dimension of the particles and to a wide size distribution, an increased filler load can be achieved with the consequence of reducing the polymerization shrink- age27 and increasing the mechanical properties, such as tensile strength, compressive strength, and resistance to fracture. These properties seem to be equivalent to or even sometimes higher than those of universal composites, and significantly higher when compared to microfilled compos- ites.24,26,27 Besides, the optical properties of these resin composites are improved, as the diameters of the filler par- ticles are a fraction of the wavelength of visible light (0.4 to 0.8 μm).24 Additionally, better gloss retention and diminished wear rate have also been reported in some studies.24,32 One of these materials is Filtek Supreme, which contain zirconia-silica particles consisting of 5- to 75-nm fillers and 0.6- to 1.4-μm nanoclusters.1 Another one, Grandio, intro- duced in early 2003, contains glass-ceramic particles of 1 μm and silicium dioxide particles of 20 to 50 nm.37 Be- sides the innovations in the field of resin composites, there have been important developments in dentin adhesive sys- tems as well. Most of the current adhesive systems require two or few- er steps and can be divided into two main groups: total-etch and self-etching systems. The total-etch systems are offered as three- or two-step systems (self-priming or one-bottle). The self-etching systems are divided into two- or one-step sys- tems (all-in-one).14 Self-etching adhesives, which are finding increasing use,7,23 do not require a separate acid etching step and only modify the smear layer. Considering that there may be some bacteria left inadvertently in the smear layer, an antibacterial self-etching adhesive system may be of great benefit in eliminating the residual bacteria in the cav- ity after operative procedures. The use of antibacterial self- etching systems subsequently increases the success rate of minimally invasive treatments.18 Since 1995, Imazato et al16,17 have conducted investigations on the use of the an- tibacterial monomer methacryloxy dodecyl pyridinium bro- mide (MDPB) for dentin bonding systems. In 2004, an an- tibacterial self-etching adhesive system containing MDPB (Clearfil Protect Bond) was introduced with the aim of ex- hibiting strong antibacterial activity against residual bacte- ria in the cavity when applied, as well as inhibition of the bac- teria that invade through microleakage after being cured by a “contact active” effect.15 Türkün34 investigated the clini- cal performance of Clearfil Protect Bond and Xeno III (Dentsply De Trey; Konstanz, Germany) in noncarious cervi- cal lesions. The one-year results demonstrated that Clearfil Protect Bond performed well during this period without caus- ing any postoperative sensitivity or side effects. Currently, there is no clinical trial comparing the perfor- mance of two different nanocomposites placed with this new antibacterial system in posterior restorations. It is well established that clinical trials are crucial for assessing all the potential variables which influence the overall perfor- mance of a restorative. Therefore, the aim of this university dental hospital-based study was to evaluate the clinical suc- cess potential of two nanocomposites placed in posterior teeth using an antibacterial adhesive system. MATERIALS AND METHODS A total of 30 patients (23 female, 7 male patients, mean age 23.9 years with a range of 13 to 48 years) participated in this study. Patients were selected for this study according to the following criteria: • No allergy to resin materials or components of adhesives. • Absence of pain related to restored teeth. • No pathological periodontal or pulpal diagnosis. • No need of deep caries treatment among the selected teeth. • An opposing or neighboring tooth to the tooth to be re- stored exists. • There are at least two comparable cavities to be restored with a resin composite. The exclusion criteria were clinical symptoms of pulpitis, such as spontaneous pain or sensitivity to pressure. En- dodontically treated teeth were also excluded. It was not obligatory for the patients to return for recalls; however, pa- tients who would not be able to return for the controls were not accepted for this clinical trial. The patients were not se- lected from a certain pool; they were asked whether they wanted to participate in the study. Participants were routine patients of a large university dental hospital serving a so- cioeconomically less advantaged part of a greater metro- politan area. The study design was approved by the Human Ethical Research Committee of Ege University (Izmir, Turkey). Written informed consent was obtained from every patient in this investigation. The indications for treatment were pri- mary caries or replacement of existing insufficient restora- tions. The clinicians, having experience with adhesive com- posite restorations, were calibrated in terms of using the ma- terials. In the course of the present controlled prospective clini- cal study, 96 cavities in 64 molars and 32 premolars were restored with one nanohybrid resin composite, Grandio (Vo- co; Cuxhaven, Germany), or one nanofilled resin composite, Filtek Supreme (3M ESPE; St Paul, MN, USA), in 30 patients in a split-mouth design. Forty-nine cavities were Class I and 47 cavities were Class II; 52 cavities were in the maxillary and 44 were in the mandibular arch.The self-etching, an- tibacterial dentin adhesive system, Clearfil Protect Bond (Ku- raray; Osaka, Japan), was used according to the manufac- turer’s instructions. The properties of the materials are pre- sented in Table 1. Equal numbers of both materials were 210 The Journal of Adhesive Dentistry Ergücü/Türkün
  • 3. Vol 9, No 2, 2007 211 Ergücü/Türkün placed in each patient. The numerical vitality test scores of the teeth before any preparations were recorded using a vi- tality tester. The cavity preparation was achieved with a con- servative adhesive design. The margins received no bevel preparations. The Class I caries extended one-fourth to one- third of the way up one or more of the cuspal slopes. The proximal portion of the Class II caries extended into the in- terproximal embrasures. The restorations were mostly qual- ified as small to moderate (80%),29 while the remaining 20% larger restorations were also included. The adhesive prepa- ration of teeth where amalgam was replaced did not result in a transformation of the existing undercuts to a nonreten- tive form. In those cases, only a trimming of the margins was conducted to cut enamel in the right direction. Teeth were isolated with cotton rolls, while rubber-dam was used for 4 teeth with deep proximal cavities. The percentages of Grandio and Filtek Supreme restora- tions in the maxillary and mandibular arches are shown in Table 2. Fifty-two percent of the Grandio restorations and 50% of the Filtek Supreme restorations were one-sided, while 44% of the Grandio and 46% of the Filtek Supreme restorations were two-sided. Only 4% of both Grandio and Fil- tek Supreme restorations were three-sided. The protocol was the same for all restorations. The primer of Clearfil Protect Bond was applied to the cavity, left undis- turbed for 20 s, and evaporated with an air syringe for a few seconds. Then the bonding agent was applied with a brush, gently spread with an air syringe and polymerized for 10 s with the Degulux light-activating unit with an output in ex- cess of 450 mW/cm2 (Degussa; Düsseldorf, Germany). The proximal portion of the Class II cavity peparations extended into the interproximal embrasures. Pre-wedging with an anatomically contoured wooden wedge (Kerr Hawe; Bioggio, Switzerland) was done before Class II cavity preparation. This procedure allowed slow separation and served as a guide to determine the proper height of the gingival floor. A sectional precontoured matrix system (Palodent, Dentsply De Trey; Konstanz, Germany) was used to restore the Class II cavities. For all the cavities, the composite resins were in- serted with hand instruments using an incremental tech- nique. The first increment, 1 to 1.5 mm thick, was con- densed in the opposite corner and light cured on that side. Material Adhesive Clearfil Protect Bond (Kuraray, Osaka, Japan) Resin based composite Filtek Supreme (3M ESPE, St Paul, MN, USA) Grandio (Voco, Cuxhaven, Germany) Table 1 Composition of materials tested* Composition/property Primer: 10-methacryloyloxydodecyl dihydrogen phosphate (MDP), 12-methacryloyloxydodecylpyridinium bromide (MDPB), 2-hydroxyethyl methacrylate (HEMA), hydrophilic dimethacrylate, water Bond: 10-methacryloyloxydodecyl dihydrogen phosphate (MDP), bis-phenol A diglycidylmethacrylate (bis-GMA), 2-hydroxyethyl methacrylate (HEMA), hydrophobic dimethacrylate, di-camphorquinone, N,N- diethanol-p-toluidine Matrix: bis-phenol A diglycidylmethacrylate (bis-GMA), triethylene glycol dimethacrylate (TEG-DMA), urethane dimethacrylate (UDMA), bisphenol A polyethylene glycol diether dimethacylate Filler: silica nanofillers (5-75 nm) zirconia/silica nanoclusters (0.6-1.4μm) Filler content: 78.5% (w/w) 59% (v/v) Matrix: bis-GMA, dimethacrylate, urethane dimethacrylate (UDMA), triethylene glycol dimethacrylate (TEG-DMA) Filler: silicium dioxide nanofillers (20-50 nm) glass ceramic microfillers (1 μm) Filler content: 87% (w/w) (71.4% (v/v) * All composition and property information is from the resp. manufacturer’s technical manual. Resin Maxillary arch Mandibular arch Total composites Premolar Molar Premolar Molar Grandio 23% 31% 35% 11% 100% Filtek Supreme 19% 35% 31% 15% 100% Table 2 Distribution of restorations by localization
  • 4. Ergücü/Türkün 212 The Journal of Adhesive Dentistry Succeeding increments 1.5 to 2 mm thick were placed and sequentially light cured until the proximal and occlusal con- tours were restored fully. Each increment was polymerized for 20 s using the same visible light-curing device. After re- moval of the matrix band, the proximal regions of the Class II restorations were separately polymerized buccally and lin- gually for 20 s each. The restorations were finished under water-spray cooling with fine-grit diamond burs to remove gross excess (No.859 EF.314.014, Komet Dental; Lemgo Germany), followed by Enhance points (Dentsply DeTrey) and Sof-Lex finishing brushes (3M ESPE; St Paul, MN, USA) to ob- tain a smooth, reflective occlusal surface. For approximal fin- ishing and polishing, finishing strips (3M ESPE) and Sof-Lex disks (3M ESPE) were used. Two volunteer clinicians, trained in the technique and not involved with the treatment procedures, examined the restorations at baseline (one week after placement), and at 6,12, and 18 months, and evaluated them using the modi- fied Ryge criteria, commonly known as US Public Health Ser- vice (USPHS) criteria.21,30 Evaluation parameters included color matching ability, marginal adaptation, anatomical form, cavosurface margin discoloration, secondary caries formation, and surface texture (Table 3). For each of the cri- teria, Alpha indicates the highest degree of clinical accept- ability; Bravo and Charlie indicate progressively lessening degrees of clinical acceptability. When disagreement oc- curred during evaluation, the final decision was made by consensus of the evaluators, who were calibrated before the study by a joint examination of 20 resin-based composite restorations each. The evaluators recorded numerical vital- ity scores at each recall. Both cavities were photographed (Canon Power Shot S45; Kyushu, Japan) at baseline and at Criterion Color-matching ability Cavosurface margin discoloration Marginal adaptation (occlusal and proximal) Secondary caries formation Surface texture Anatomical form (occlusal and proximal) Inspection method Visual inspection with a mirror at 18 inches Visual inspection with a mirror at 18 inches Visual inspection with explorer and mirror, if needed Visual inspection with explorer, mir- ror and radiographs Visual inspection with explorer and mirror, if needed Visual inspection with explorer and mirror, if needed Rating scale A: The restoration matches the adjacent tooth structure in color and translucency. B: Light mismatch in color, shade or translucency between the restoration and the adjacent tooth. C: The mismatch in color and translucency is outside the ac- ceptable range of tooth color and translucency. A: No discoloration anywhere along the margin between the restoration and the adjacent tooth. B: Slight discoloration along the margin between the restoration and the adjacent tooth. C: The discoloration penetrated along the margin of the restora- tive material in a pulpal direction. A: No visible evidence of a crevice along the margin B: Visible evidence of a crevice along the margin into which the explorer will penetrate. C: The dentin or base is exposed. D:The restoration is fractured, mobile or missing. A: No evidence of caries. B: Evidence of caries along the margin of the restoration. A: The restoration surface is as smooth as the surrounding enamel. B: The restoration surface is rougher than the surrounding enamel. C: There is a crevice and fracture on the surface of the restora- tion. A: The restoration is continuous with existing anatomical form. B: The restoration is discontinuous with existing anatomical form, but the material is not sufficient to expose the dentin or base. C: Sufficient material lost to expose the dentin or the base. Table 3 Modified Ryge direct evaluation criteria* * Source: Ryge A: Highest degree of clinical acceptability; B and C: less clinical acceptability, D: clinically unacceptable
  • 5. Vol 9, No 2, 2007 213 Ergücü/Türkün each recall appointment. For each subject, the number of teeth restored using each nanocomposite was equal, so that each restoration could be compared with its own same-sub- ject control. The Cochran-Q test was used to evaluate the changes across the four time points for each of the criteria. The two resin composites were compared at the same recall period for each criterion using the McNemar test. For all of the sta- tistical analyses, p was set at 0.05. RESULTS Thirty patients requiring posterior resin composite restora- tions were included in this study; however, two patients were unavailable for recall appointments because they had moved. Of the 96 restorations placed, 90 novel resin com- posite (Grandio and Filtek Supreme) restorations that were placed with the antibacterial two-step adhesive system (Clearfil Protect Bond) in 28 patients were evaluated at the 18-month recall appointment. The clinical assessment re- sults are shown in Table 4. Esthetics and tooth vitality were all rated satisfactory for the two nanocomposites investigated (Figs 1 and 2). Gingi- val response was evaluated with a periodontal probe using a gingival index.31 There was no inflammation, color change, or bleeding around the restorations, and gingival status was normal. None of the restorations showed evidence of sec- ondary caries formation (Figs 3 and 4)
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