Bond Strength of Fiber-Reinforced Composite Resin Restorations

Severe tooth wear is common in older dentate individuals, with one treatment option being composite resin restorations reinforced with a suitable matrix. This study evaluated the use of high modulus polyethylene (Celanese) fibers as a reinforcing matrix for composite resin. Human mandibular incisor teeth were sectioned to simulate severe tooth wear. Sectioned surfaces were measured, the teeth paired and assigned to control or test sample groups, and further assigned to be tested with a labial or lingual shearing force. A phosphorylated dentin bonding adhesive was applied to the abraded dentin surface. Labial and lingual intra-enamel bevel preparations were cut on each specimen. A piece of Celanese fabric was bonded onto the acid-etched labial and lingual bevels of the test specimens using an enamel bonding agent. Class IV composite resin restorations were then placed onto the test and control specimens. Following water storage, the specimens were subjected to shearing forces. Bond strengths for test specimens were significantly greater (p < 0.03) than the controls. Specimens with a labially applied force also had significantly higher bond strengths (p < 0.001). SEM analysis revealed adhesive bond failures over dentin surfaces, with cohesive bond failures within the composite resin. Celanese fibers maintained the restorations on the teeth, although adhesive failures were seen between the fibers and enamel bonding agent.     

Effect of Two Abrasive Systems on Resin Bonding to Laboratory-Processed Indirect Resin Composite Restorations

Abstract: Purpose: This study compared two methods of surface roughening or preparation, with or without the use of proprietary surface wetting agents, to evaluate their effect on resin cement adhesion to the following laboratory-processed, indirect restorations: Artglass (AG), belleGlass HP (BG), Concept (C), and Targis (T). Methods of surface roughening or preparation included microetching with aluminum oxide (AC): 50 μm at 34 psi and silanized silica coating, CoJet-Sand (CJ): 30 μm at 34 psi. Artglass and Concept were tested with and without the use of their respective surface wetting agents: Artglass Liquid (AGL) and Special Bond II (SB). Materials and Methods: One hundred twenty specimens, each consisting of a pair of cylinders (7.0 × 3 mm and 4.3 × 3 mm) were fabricated. The larger cylinder or base was embedded in self-curing resin in a phenolic ring, and bonding surfaces were finished with 320-grit silicon carbide paper. Specimen pairs for each restorative material were randomly assigned to treatment groups (n = 10) and received the following surface treatments prior to cementation group 1 (AG/AO/+AGL), group 2 (AG/AO/-AGL), POUP 3 (AG/CJ/+AGL), group 4 (AG/CJ/-AGL), group 5 (BG/AO), group 6 (BG/CJ), group 7 (C/AO/+SB), group 8 (C/AO/-SB), group 9 (C/CJ/+SB), group 10 (C/CJ/-SB), group 11 (T/AO), and group 12 (T/CJ). Specimen pairs were cemented with a dual-cure resin cement (Dual) and a standardized force of 1 MPa. Specimens were light-cured 40 seconds per side (80 s total), then thermocycled 300 times at between 5° and 55°C. Shear bond strengths (MPa) were determined using a Zwick Materials Testing Machine at a crosshead speed of 5 mm per minute. Results: One-way analysis of variance (ANOVA) and Duncan's multiple range test (α= 0.05) by restoration type indicated no significant differences in shear bond strength between BG group 5 (29.8 ± 5.8), BG group 6 (28.3 ± 4.3), T group 11 (29.3 ± 4.9), and T group 12 (29.0 ± 4.4). Shear bond strength in AG group 3 (35.9 ± 3.4) was significantly higher than in AG group 4 (32.4 ± 4.0) and equal to that in AG group 2 (31.9 ± 3.9) and AG group 1 (30.0 ± 3.6). Shear bond strength in C group 10 (24.8 ± 5.7) was equal to that in C group 9 (21.5 ± 2.9), but was higher than in C groups 7 (19.4 ± 3.1) and 8 (19.3 ± 3.4).     

不同配色方案对复合树脂双层修复颜色的影响

目的:研究不同牙釉质/牙本质树脂配色方案对复合树脂双层修复颜色效果的影响。方法:选择2个品牌(Z350,NG)按照牙釉质色与牙本质色一致(方案1),牙本质色比牙釉质色加深一个色号(方案2),牙釉质色统一为A3色(方案3)3种配色方案制作釉质层1.0 mm厚双层修复树脂试样,分光光谱仪测量获取试样颜色参数并计算与Vita经典比色板的色差(ΔE)。结果:2种树脂品牌及3种配色方案的ΔE值均有统计学差异(P<0.05)。Z350的ΔE值均小于NG。对于A1色,方案一的△E值最小;对于A2色,方案1、2的ΔE值小于方案3。结论:对于釉质层1.0 mm厚的树脂双层修复,Z350颜色与比色板颜色更接近;对于A1色,牙釉质色与牙本质色一致的传统配色方案与A1色比色板颜色最接近;对于A2色,传统方案与牙本质色比牙釉质色深一个色号的配色方案与A2色比色板颜色更接近。     

A Conservative Treatment for Amelogenesis Imperfecta with Direct Resin Composite Restorations: A Case Report

Rehabilitation of a patient with amelogenesis imperfecta (AI) from both the functional and esthetic standpoints represents a challenge. The complexity of the condition requires an interdisciplinary approach for optimal treatment outcomes. A number of treatment options have been proposed. Recently, the use of bonded restorations has gained popularity because of the many benefits associated with these materials; excellent esthetics, conservative approach, and improved wear make their use advantageous. This article describes a direct approach with resin composite restorations for the transitional treatment of an adolescent with hypoplastic AI who had not completed skeletal growth. Protection against further wear, sensitivity, and plaque accumulation while significantly enhancing the patient's esthetic appearance made this case a success. Furthermore, this article describes the use of a Clear matrix technique, which considerably helped simplify the placement of the bonded restorations.

CLINICAL SIGNIFICANCE

This article highlights (1) the importance of an interdisciplinary approach to the successful treatment planning of a patient with hypoplastic amelogenesis imperfecta (AI), and (2) the conservativeness and suitability of full coverage direct resin composite restorations for the transitional treatment of AI-affected teeth on an adolescent patient who has not yet completed skeletal growth.     

Light-Cured Resin Cements for Cementation of Esthetic Restorations

Properties and clinical indications of light-cured resin cements used for cementation of porcelain veneers, all-porcelain crowns, and tooth-colored inlays and onlays are reported.     

The Short-term Clinical Performance of a Silorane-based Resin Composite in the Proximal Contacts of Class II Restorations

Aim: The aim of this randomized clinical trial was to compare the proximal contact of a silorane-based resin composite with a conventional methacrylate-based resin composite in class II restorations after a 6 months follow-up period. Materials and methods: After obtaining informed consent, 33 patients were randomly allocated into a test group (Filtek P90/Adhesive System-3M ESPE) or control group (Filtek P60/ Adper SE Plus-3M ESPE), and 100 direct resin composite restorations (n = 50) were placed. A single operator performed the cavities and restorations. After rubber dam placement, a metal matrix and wooden wedge were placed. The restorative systems were applied according to the manufacturer's instructions. After 1 week, the restorations were finished and polished. The proximal contacts were assessed blindly and independently by two calibrated examiners (kW = 0.8) at the baseline and after 6 months according to a three-step grading criteria. Data were analyzed with the Mann-Whitney U-test and Wilcoxon signed Rank tests (a = 0.05). Results: After 6 months, 96% of the restoration contacts were present for evaluation. The frequencies of restorations classified as Bravo in control and test groups were 6 and 8% at the baseline, and 6.25 and 12.75% after 6 months. No significant difference was found between the restorative materials (p > 0.05; Mann-Whitney U-test) neither between baseline and 6 months period (p > 0.05; Wilcoxon signed Rank tests). Conclusion: Both materials performed satisfactorily over 6 months follow-up period. Clinical significance: The short-term clinical performance of a silorane-based resin composite in the proximal contacts of class II restorations was similar to the well-known methacrylate-based resin composite. Keywords: Clinical trial, Resin composite, Silorane, Proximal contact. How to cite this article: Goncalves FS, Castro CDL, Bueno AC, de Freitas ABDA, Moreira AN, Magalhaes CS. The Shortterm Clinical Performance of a Silorane-based Resin Composite in the Proximal Contacts of Class II Restorations. J Contemp Dent Pract 2012;13(3):251-256. Source of support: FAPEMIG (Process CDS-APQ-01606-09) and CNPq (Process 474679-2009 8) Conflict of interest: None declared.     

Polymerization Contraction Stress of Resin Composite Restorations in a Model Class I Cavity Configuration Using Photoelastic Analysis

Purpose: An important factor that contributes to deterioration of resin composite restorations is contraction stress that occurs during polymerization. The purpose of this article is to familiarize the clinician with the characteristics of contraction stress by visualizing the stresses associated with this invisible and complex phenomenon. Materials and Methods: Internal residual stresses generated during polymerization of resin composite restorations were determined using micro‐photoelastic analysis. Butt‐joint preparations simulating Class I restorations (2.0 mm ± 5.0 mm, 2.0 mm in depth) were prepared in three types of substrates (bovine teeth, posterior composite resin, and transparent composite resin) and were used to examine contraction stress in and around the preparations. Three types of composite materials (a posterior composite, a self‐cured transparent composite, and a light‐cured transparent composite) were used as the restorative materials. The self‐cured composite is an experimental material, and the others are commercial products. After treatment of the preparation walls with a bonding system, the preparations were bulk‐filled with composite. Specimens for photo‐elastic analysis, were prepared by cutting sections perpendicular to the long axis of the preparation. Fringe patterns for directions and magnitudes of stresses were obtained using transmitted and reflected polarized light with polarizing microscopes. Then, the photoelastic analysis was performed to examine stresses in and around the preparations. Results: When cavity preparations in bovine teeth were filled with light‐cured composite, a gap was formed between the dentinal wall and the composite restorative material, resulting in very low stress within the restoration. When cavity preparations in the posterior composite models were filled with either self‐cured or light‐cured composite, the stress distribution in the two composites was similar, but the magnitude of the stress was greater in the light‐cured material. When preparations in the transparent composite models were filled with posterior composite and light‐cured transparent composite material, significant stress was generated in the preparation models simulating tooth structure, owing to the contraction of both restorative materials. CLINICAL SIGNIFICANCE Polymerization contraction stress is an undesirable and inevitable characteristic of adhesive restorations encountered in clinical dentistry that may compromise restoration success. Clinicians must understand the concept of polymerization contraction stress and realize that the quality of composite resin restorations depends on successful management of these stresses.