|Year : 2021 | Volume
| Issue : 2 | Page : 79-85
Clinical performance of a direct submicron hybrid and indirect zirconium reinforced composite restorations: A 2-year assessment
Vijetha Vishwanath, Murali H Rao, BS Keshava Prasad
Department of Conservative Dentistry and Endodontics, DA Pandu Memorial RV Dental College, Bengaluru, Karnataka, India
|Date of Submission||08-Nov-2020|
|Date of Decision||05-May-2021|
|Date of Acceptance||07-May-2021|
|Date of Web Publication||30-Jun-2021|
Dr. Vijetha Vishwanath
DA Pandu Memorial RV Dental College, Bengaluru, Karnataka
Objective: To evaluate the clinical efficacy of direct and indirect composite resin restorations placed in posterior teeth after 2 years. Materials and Methods: A total of 60 teeth were restored with a direct composite resin (BRILLIANT EverGlowTM– Coltene) and an indirect composite resin (CeramageTM– Shofu). All restorations were assessed using the Modified United States Public Health Service criteria at baseline, 3 months, 6 months, 12 months, 18 months, and 24 months after placement. Statistical analysis was performed with Chi-Square test and Cochran's Q test. Results: At the 2-year evaluation, all restorations were retained, with Alpha ratings at 100%. Only two teeth (in the direct restoration group) required endodontic intervention after 18 months due to secondary caries. Surface texture, marginal discoloration, and marginal integrity were predominantly scored as Alpha after 2 years for both groups. Color match was scored as Alpha in 65.4% of direct restorations and 84.4% of indirect restorations. Conclusion: Within the limitations of this study it can be concluded that the clinical performance of the indirect restorations was much improved than that of direct restorations.
Keywords: Clinical evaluation, clinical performance, composite inlay, direct submicron hybrid composite, indirect technique, modified United States Public Health Service, posterior teeth
|How to cite this article:|
Vishwanath V, Rao MH, Keshava Prasad B S. Clinical performance of a direct submicron hybrid and indirect zirconium reinforced composite restorations: A 2-year assessment. SRM J Res Dent Sci 2021;12:79-85
|How to cite this URL:|
Vishwanath V, Rao MH, Keshava Prasad B S. Clinical performance of a direct submicron hybrid and indirect zirconium reinforced composite restorations: A 2-year assessment. SRM J Res Dent Sci [serial online] 2021 [cited 2021 Jul 31];12:79-85. Available from: https://www.srmjrds.in/text.asp?2021/12/2/79/319864
| Introduction|| |
Restorative dentistry makes up 60% of all dental work in everyday practice. Although materials such as amalgam and gold have shown longevity of service, patients often demand for esthetic alternatives. Currently, the improved resin-based restorative materials are being used extensively to meet aesthetic and functional demands.
Resin composites have gone through generations due to the modifications in the filler structure and properties. Newer resin formulations having a combination of both submicron particles (0.04 μm) and small particles (0.1 μm–1.0 μm) with higher filler loading percentages have been developed and are classified as submicron hybrid composite. They demonstrate better mechanical and physical properties in addition to improved polishability and gloss retention producing restorations with better finish and aesthetics. These can be optimally used for direct restoration of both anterior and posterior teeth.
Indirect laboratory-processed composite resin systems are a viable esthetic alternative for posterior teeth. Its composition is analogous to that of direct composite but differs in the utilization of additional polymerization, which causes better free radical conversion. Ceramage is an indirect composite resin system with 73% of zirconium silicate filler embedded in an organic polymer matrix. They show properties similar to ceramic such as excellent polishability, high resistance to plaque, and structural durability making it an ideal posterior restorative material.
Although numerous in vitro studies, have been conducted to predict the durability of composite restorations in clinical applications, they do not always reflect the true behavior of the material due to the inability to simulate the exact oral environment. For this reason, clinical studies have great importance. The United States Public Health Service (USPHS) evaluation system, is the most commonly used direct method for the quality control of restorations, as they provide comprehensive evidence for clinical acceptance, rather than for degrees of clinical success.
The aim of this study was to compare and evaluate the clinical parameters between direct restorations performed with a new universal submicron hybrid composite (BRILLIANT EverGlowTM– Coltene) and indirect restorations processed with zirconium silicate-based composite (CeramageTM– Shofu) on posterior teeth, with 2 years follow-up to draw outcome-based conclusions.
| Materials and Methods|| |
Patients within the age group of 20–50 years, with good oral hygiene, healthy pulpal and periodontal status, having natural dentition directly opposing the test restoration (First and/or second mandibular and/or maxillary molar) and those willing to participate in the study were included.
Patients with chronic systemic diseases with or without oral manifestations, poor oral hygiene, gross dental caries, severe periodontal problems or any wasting disease, known allergy to any materials used in the study, tooth with directly opposing porcelain restorations or teeth that would be used as an abutment for removable or fixed partial dentures were excluded.
Setting and location
The research protocol received ethical clearance from the Institutional Review Board (195/Vol-2/2016). The study participants were recruited from the pool of patients of the Department of Conservative Dentistry and Endodontics, D A Pandu Memorial R. V Dental College and Hospital, Bangalore, Karnataka, India. Before conducting the study, written consent was obtained from all the subjects selected for the study who satisfied the inclusion criteria. A detailed case history was obtained followed by a thorough clinical examination under adequate illumination and aseptic conditions. All patients received thorough oral prophylaxis and hygiene instructions before restorative intervention.
Sample size calculation
The sample size has been estimated using the software GPower v. 184.108.40.206 (G Power software Version 220.127.116.11, Franz Faul, Universitāt Kiel, Germany, March 2014). Considering the effect size to be measured at 80%, power of the study at 80%, and the margin of the error at 5%, the total sample size was calculated as 52, rounding the sample size to 60 to overcome attrition. Two groups of 30 samples were formed.
The method (direct/indirect) chosen to restore the tooth was primarily influenced based on the clinical situation and radiographic investigation. Small and medium-sized defects (isthmus width >1½ to two-thirds of the intercuspal distance) were completed by incremental technique, while in larger defects (width of the isthmus exceeds two-thirds) composite inlays were bonded. The two evaluators who assessed all restorations of both the group were not aware of the type of restoration.
Restorative materials composition
Brilliant EverglowTM, a sub-micron hybrid direct composite, has a composition as outlined by Lopes et al.  and CeramageTM, an indirect composite, has composition as outlined by Soance et al. and Nishimaki.
Protocol for direct restoration
The teeth were thoroughly cleaned followed by pumice prophylaxis. The shade of the tooth was determined using the composite shade tab provided by the manufacturer (BRILLIANT EverGlowTM shade guide), further the closest shade was determined with the help of small amount of polymerized composite resin on the buccal surfaces before conditioning of the tooth. Then, the tooth was prepared to obtain rounded internal angles with margins in the enamel. A Calcium Hydroxide cavity liner (Calcimol LCTM, VOCO America, Inc) was used as a sub-base in dentinal areas close to the pulp followed by Glass ionomer cement (XtraCem-LCTM, Medicept, UK) as a base after rubber dam (HygienicTM, Coltene, Switzerland) isolation. The enamel margins were etched and rinsed with 37% orthophosphoric acid gel and bonding agent (One Coat 7 UniversalTM, Coltene) was applied in thin layer and cured. Matrix band and wedges ensured proper contact. The restorative procedure was carried out by incremental layering of 1 mm or less, from the proximal box and completed. The surface of restoration was covered with glycerin gel before a final 20s irradiation. The occlusion was checked, refined, and polished using fine diamond abrasives and silicone points post rubber dam removal.
Protocol for indirect restoration
Tooth preparation was done as required for indirect restorations with slightly divergent walls, no bevels, and the margins were located in enamel. Undercuts were blocked by using glass-ionomer cement (XtraCem-LCTM, Medicept, UK). A Vinyl polysiloxane impression (Aquasil and ReprosilTM, Dentsply, USA) was made and the cast was poured immediately with die stone. The tooth was temporized. After die-cutting, a thin-even layer of die spacer (CeremageTM spacer) was applied on the cavity floor except near the margins, to achieve adequate space for resin cement during the final placement of the restoration. Next, a thin layer of separator (Ceramage Sep) was applied to ensure easy separation of the restoration from the die. The inlay was gradually built up in increments by using the appropriate dentin and enamel shades (Ceramage composite resin) and each layer was light-cured for 40 s using curing units (Prepolymerization unit– 150W Sublite V; Secondary polymerization unit– 600W Solidilite V, Shofu IncTM, Japan). After the layering procedure was completed, Universal Oxybarrier gel (Ceramage) was applied on the entire inlay and cured for 3 min. Occlusal prematurity, marginal adaptation, and proximal contacts were modified by try-in and the restoration was subjected to secondary polymerization for 7 min.
The tooth preparation was cleaned with normal saline and gently dried. Non-Rinse Conditioner (ParacoreTM, Coltene, Switzerland) was applied onto the prepared surface uniformly for 30 s without excess. Next, the components of the adhesive (Paracore) were mixed and applied homogeneously within the working time of 2 min. A thin layer of bonding agent was coated on the fitting surface of inlay, which was left uncured. Transparent shade of dual-cure resin cement (Paracore) was injected in the preparation with a syringe to prevent the change of shade of the final restoration. Then the inlay was placed with gentle pressure until complete seating to ensure an optimum film thickness of 15–20 μm. The excess cement was removed occlusally and inter proximally with a probe and waxed dental floss after tack cure. Each surface was light-cured for 40s and a final cure of 20s after applying a glycerin gel coat. Finishing and polishing were completed.
Evaluation of outcome
The two evaluators, who were not involved in the process of restoration, received an assessment sheet where the restorations were rated independently using magnifying loupes. Where scores did not tally, a consensus decision was made. The restorations were assessed using Modified USPHS criteria for anatomic form, marginal adaptation, color match, marginal staining, surface roughness, and secondary caries at baseline, 3 months, 6 months, 12 months, 18 months, and 24 months.
The Statistical Package for the Social Sciences (SPSS) for Windows Version 22.0 Released 2013. Armonk, NY, USA: IBM Corp., was used to perform statistical analyses. Descriptive analysis of the Clinical Evaluation parameters for Direct and Indirect Composite Restorations was done using frequency and proportions. Chi-square test was used to compare the clinical evaluation of different study parameters between the two groups at different time intervals. Cochran's Q test was used to compare the study parameters between different time intervals in each study group. The level of significance was set at P < 0.05.
| Results|| |
Of the 60 study paticipants, 28 patients received direct restorations and 32 patients received indirect restorations. The mean age was 32 years with a standard deviation of 7.515. A total of 34 females (direct-18; indirect-16) and 26 males (direct-10; indirect-16) received the restorations for which the statistical analysis was performed. After 24 months, the recall rate was 100% for clinical assessment. When compared with the baseline evaluation, most criteria showed a progressive change of the scores at different intervals [Table 1], [Table 2], [Table 3]. Indirect restorations scored significantly (84.4%) better than direct (65.4%) in terms of color stability at the end of 2 years [Table 4]. There was not much difference in marginal discoloration clinically, though at the 24th month recall it was seen that direct restoration recorded a score of 73.1% and indirect scored 68.8% in α and proportionate complement for β category [Table 4]. For surface texture [Table 4], both the groups scored high in α from baseline up to 18 months recall after which the direct group showed decrease in performance relatively (73.1%). Both the groups showed consistent scores for marginal adaptation in α (alpha) category (80%–85%) throughout the study [Table 5]. However, the indirect group showed an increased β (bravo) score of 31.3% at 24th-month recall. The indirect restorations scored better for anatomic forms than direct restorations from baseline to 24 months in α and β category which is statistically significant. The restorations were evaluated for secondary caries, and 100% α ratings were obtained for indirect restorations from baseline to 24 months follow-up. However, two direct restorations showed failure due to secondary caries at 18 months and needed endodontic intervention. Postoperative sensitivity was slightly greater for direct polymerization (25%) than the indirect polymerization method (20%) at baseline after which neither group scored during periodic recalls.
|Table 1: Comparison of clinical evaluation of different study parameters between direct and indirect composite inlay restorations at baseline, 3 and 6 months using Chi-square test|
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|Table 2: Comparison of clinical evaluation of different study parameters between direct and indirect composite inlay restorations at 12, 18 and 24 months post-Rx period using Chi-square test|
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|Table 3: Comparison of clinical evaluation of different study parameters between direct and indirect composite inlay restorations at baseline period and 24 months using Chi-square test|
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|Table 4: Comparison of clinical evaluation of color match, marginal discolouration and surface texture parameter between different time intervals in each group using Cochran's Q test|
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|Table 5: Comparison of clinical evaluation of marginal adaptation, anatomic form and secondary caries parameter between different time intervals in each group using Cochran's Q test|
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| Discussion|| |
Clinical research is most significant method to evaluate the performance of dental restorations and techniques, as they are subjected to masticatory forces, salivary enzymes, food, chemicals and microbial action.
At all the evaluation periods in this study, the recall rate was 100% which could be attributed largely to self-motivated patients towards tooth colored restorations and a lesser cost on account of institutional setting.
Color match and postoperative discoloration of restoration depends on number of factors such as the restorations' surface structure, interaction between the resin matrix and filler particles and with the external environment. The color match ability of a greater percentage of samples in indirect restorations from baseline to final evaluation could be attributed to their ability to maintain surface characteristics much better. This is due to their better dimensional stability on account of additional curing procedures. This increases wear resistance than direct composite restorations, which undergo only intraoral curing. The high percentage (92.9%) of color match of direct composite could be attributed to the filler size, which is below a micron (submicron) which renders high polishablility and surface gloss. In recall visits, the percentage score was relatively less (65.4%) which could be attributed to increased surface wear. These findings concur with previous studies, where indirect restorations scored better than direct restorations in long run.
Both the restorations were able to sustain marginal integrity for 18 months after which some changes were seen. This could be due to the opening up of tooth-restoration interface on account of masticatory stresses, which is inherent with any type and technique of composite restorations. The two groups scored consistently in both α and β categories from baseline to final evaluation, which were comparable with the previous study. Few studies, have shown a higher rate of marginal discoloration in indirect restoration due to cement wear whereas others have reported a higher value in direct restorations, with insufficient significant differences.
The scores clinically conveyed that both the techniques were able to render a smooth surface texture for 1 year or more and only after that, reintervention was needed to improve the quality of existing restorations. This is true for most of the posterior restorations as they are in occlusal contact serving functional requirements. Indirect restorations showed better scores in both α and β categories on account of improved mechanical properties and superior aesthetics due to additional extraoral secondary polymerization (Tempering). Similar findings were seen in previous studies, where after 5 years of clinical service, more indirect restorations received α ratings for surface texture compared with direct restorations.,
Direct restoration showed better scores as there is a resin cement interface in indirect restorations, which has lower mechanical properties and higher wear. Hence, marginal fractures can be expected. Limitations in the marginal seal, resulting from polymerization shrinkage and longtime degradation could be the attributes for this development. However, the changes were well within clinically acceptable limits. Further, marginally high scores of direct restorations could be because, the placement of composites were on the prepared teeth, which provided the distinct advantage of manipulation of material intraorally as close as possible to the preparation periphery and the ability to minimize or correct any surface discrepancies to make the margins flush with the tooth for aesthetic demands.
The practical drawbacks of direct restorations are variations in the morphology of teeth, inability to create exact anatomical features intraorally due to restricted access, increased time, limited patient cooperation, difficulty in isolation, and inadequate convenience form in distal and deep occluso-proximal situations. In contrast, the indirect restorations are laboratory processed on a die. This provides unrestricted and convenient access, control of morphology on all surfaces, which in turn influences the anatomic contours when they are bonded onto the patient's teeth. On account of these improved features, indirect restorations scored better than direct restorations. The results of this study were in concurrence with previous studies., However, few studies, show no statistically significant difference between the two.
Both the groups performed well with respect to the incidence of secondary caries. This can be attributed to improved material properties of submicron hybrid variety to resist wear, sustain dimensional stability of direct restorations and enhanced physical and mechanical properties of indirect restorations prevented the onset of secondary caries. The use of the latest dentin adhesives for direct restorations and resin cements which bonded indirect restorations could have influenced the tooth restoration interface proximity. Therefore, marginal percolation and breakdown at this region were not significant. However, in this study, two teeth restored by direct composite could not maintain their biological and functional integrity and had to undergo endodontic intervention. This could be due to the proximity of pulp tissue and relatively less remaining dentin thickness. Similar results were seen in few studies,, where failure was seen in direct restorations while few other studies, showed no significant differences between the two groups.
In the present 2-year clinical study, direct composite restorations exhibited marginally more postoperative sensitivity than the indirect at baseline. This is an early common finding often encountered after direct composite restorations and bonding of indirect restorations. This can be attributed to the inherent polymerization contraction of composite material. Both the groups did not exhibit post operative sensitivity during periodic recalls.
| Conclusion|| |
Within the limitations of this study, the following can be concluded:
- During the 24-month follow-up period, indirect restorations exhibited higher α scores than direct restorations for color match and in the maintenance of original surface texture
- Both the restorations were able to sustain marginal integrity for 18 months after which some changes were seen. Direct restorations performed better
- Indirect restorations scored better in the maintenance of anatomic form
- Direct restoration scored marginally higher β score for secondary caries and postoperative sensitivity.
In summary, indirect composite restorations showed superior clinical performance in terms of maintenance of anatomic form, surface texture, color match, and postoperative sensitivity to direct composite restorations despite more clinical steps and elaborate procedure of fabrication. However, 2 years may not be considered sufficient for drawing definitive conclusions on the performance of direct and indirect restoration techniques. Long-term clinical evaluations are needed to validate the performance of new materials with more participating subjects.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Anusavice KJ. Criteria for selection of restorative materials: Properties versus technique sensitivity. Quality Evaluation of Dental Restorations: Criteria for Placement and Replacement. Quintessence Publishing Company, Chicago; 1989. p. 15-59.
Sonwane SR, Hambire UV. Comparison of flexural and compressive strengths of nano hybrid composites. Int J Eng Trends Appl 2015;2:47-52.
Kumari V, Pradeep PR, Soman A, Krishna A, Shankar V, Kasti KJ. Evaluation of surface roughness of composite resins with three different polishing systems and the erosive potential with apple cider vinegar using atomic force microscopy - An in vitro
study. Acta Sci Dent Sci. 2019;3.3:08-16.
Fonseca RB, Correr-Sobrinho L, Fernandes-Neto AJ, Quagliatto PS, Soares CJ. The influence of the cavity preparation design on marginal accuracy of laboratory-processed resin composite restorations. Clin Oral Investig 2008;12:53-9.
Shikder AZ, Shomi KN, Saki N, Begum F, Mahmud KH, Alam MS. Clinical evaluation of direct composite resin and indirect micro ceramic composite resin restorations in class-I cavity of permanent posterior teeth. Int J Hum Health Sci 2019;3:109-15.
Burgoyne AR, Nicholls JI, Brudvik JS. In vitro
two-body wear of inlay-onlay composite resin restoratives. J Prosthet Dent 1991;65:206-14.
Göhring TN, Besek MJ, Schmidlin PR. Attritional wear and abrasive surface alterations of composite resin materials in vitro
. J Dent 2002;30:119-27.
Cvar JF, Ryge G. Reprint of criteria for the clinical evaluation of dental restorative materials. 1971. Clin Oral Investig 2005;9:215-32.
Lopes IAD, Monteiro PJVC, Mendes JJB, Gonçalves JMR, Caldeira FJF. The effect of different finishing and polishing techniques on surface roughness and gloss of two nanocomposites. Saudi Dent J 2018;30:197-207.
Soanca A, Roman A, Moldovan M, Perhaita I, Tudoran LB, Rominu M. Study on thermal behaviour, structure and filler morphology of some indirect composite resins. Dig J Nanomater Biostruct 2012;7:1071-81.
Nishimaki M. Depth of cure and hardness of indirect composite materials polymerized with two metal halide laboratory curing units. J Oral Sci 2012;54:121-5.
Ozakar-Ilday N, Zorba YO, Yildiz M, Erdem V, Seven N, Demirbuga S. Three-year clinical performance of two indirect composite inlays compared to direct composite restorations. Med Oral Patol Oral Cir Bucal 2013;18:e521-8.
Mahmoud SH, El-Embaby AE, AbdAllah AM, Hamama HH. Two-year clinical evaluation of ormocer, nanohybrid and nanofill composite restorative systems in posterior teeth. J Adhes Dent 2008;10:315-22.
Cetin AR, Unlu N, Cobanoglu N. A five-year clinical evaluation of direct nanofilled and indirect composite resin restorations in posterior teeth. Oper Dent 2013;38:E1-11.
Pallesen U, Qvist V. Composite resin fillings and inlays. An 11-year evaluation. Clin Oral Investig 2003;7:71-9.
Angeletaki F, Gkogkos A, Papazoglou E, Kloukos D. Direct versus indirect inlay/onlay composite restorations in posterior teeth. A systematic review and meta-analysis. J Dent 2016;53:12-21.
Manhart J, Chen H, Hamm G, Hickel R. Buonocore Memorial Lecture. Review of the clinical survival of direct and indirect restorations in posterior teeth of the permanent dentition. Oper Dent 2004;29:481-508.
Wassell RW, Walls AW, McCabe JF. Direct composite inlays versus conventional composite restorations: 5-year follow-up. J Dent 2000;28:375-82.
Mendonça JS, Neto RG, Santiago SL, Lauris JR, Navarro MF, de Carvalho RM. Direct resin composite restorations versus indirect composite inlays: One-year results. J Contemp Dent Pract 2010;11:025-32.
Cetin AR, Unlu N. One-year clinical evaluation of direct nanofilled and indirect composite restorations in posterior teeth. Dent Mater J 2009;28:620-6.
Türkün LS, Aktener BO. Twenty-four-month clinical evaluation of different posterior composite resin materials. J Am Dent Assoc 2001;132:196-203.
Efes BG, Dörter C, Gömeç Y, Koray F. Two-year clinical evaluation of ormocer and nanofill composite with and without a flowable liner. J Adhes Dent 2006;8:119-26.
Fennis WM, Kuijs RH, Roeters FJ, Creugers NH, Kreulen CM. Randomized control trial of composite cuspal restorations: Five-year results. J Dent Res 2014;93:36-41.
Cetin AR, Unlu N. Clinical wear rate of direct and indirect posterior composite resin restorations. Int J Periodontics Restorative Dent 2012;32:e87-94.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]