Dental enamel bleached for a prolonged and excessive time: Morphological changes.

This work aimed to evaluate the roughness, microhardness, ultrastructure, chemical composition and crystalline structure in submitted teeth to a prolonged home bleaching regimen with 10% carbamide peroxide (10% PC) for different periods. The specimens were divided into the following groups: G1: negative control (application of water-soluble gel); G2: tooth whitening group (positive control), under application time recommended by the manufacturer (4h/14 days); G3: prolonged whitening 50%, under prolonged time recommended by the manufacturer in 50% (4h/21 days); G4: excessive whitening 100%, under exceeded manufacturer recommended time by 100% (4h/ 28 days). The results were evaluated descriptively and analytically. There were no changes in the roughness in any of the evaluated groups. However, the microhardness decreased in the G4 group. Scanning electron microscopy showed changes in the enamel surface of groups G2, G3 and G4. Dispersive X-ray spectroscopy identified changes in the concentration of chemical elements O, Mg, P, K in all groups. Thus, this study showed that prolonged home bleaching could cause changes in the ultrastructure, chemical composition and microhardness of the enamel.

Do HEMA-free adhesive systems have better clinical performance than HEMA-containing systems in noncarious cervical lesions? A systematic review and meta-analysis.

OBJECTIVES: To determine through a systematic review whether HEMA-free adhesive systems have better clinical performance than HEMA-containing systems in noncarious cervical lesion (NCCL) restorations. SOURCES: We systematically searched PubMed, The Cochrane Library, Scopus, Web of Science, and Open Grey databases using MeSH terms, synonyms, and keywords, with no language or date restriction. The reference lists of included articles were manually searched. STUDY SELECTION: Randomized controlled clinical trials comparing the effectiveness of HEMA-free and HEMA-containing adhesive systems in NCCL restorations were included. The risk of bias in the included studies was assessed and classified through the Cochrane Collaboration's common scheme for bias. Quantitative data were subgrouped according to the main clinical parameters evaluated, and heterogeneity was tested using I2 index. DATA: A total of 2889 potentially relevant studies were identified. After title and abstract examination, 51 studies remained. Finally, 22 studies were included in the systematic review, totaling to 997 participants. Thus, 13 studies were classified as "low" risk of bias and nine as "unclear". These 22 studies were also included in the meta-analysis, and no significant statistical difference was found between the clinical performances of HEMA-free and HEMA-containing adhesive systems for all parameters analyzed: retention risk difference (RD) 0.03 [-0.01, 0.07] (p = 0.13); marginal discoloration RD 0.02 [-0.01, 0.04] (p = 0.19); marginal adaptation RD -0.01 [-0.04, 0.01] (p = 0.34); caries RD 0.00 [-0.01, 0.01] (p = 0.92); or postoperative sensitivity RD -0.00 [-0.02, 0.01] (p = 0.72) and for overall effect RD 0.00 [-0.01, 0.01] (p = 0.65). CONCLUSIONS: HEMA-free and HEMA-containing adhesive systems showed a similar clinical performance in NCCL restorations. CLINICAL SIGNIFICANCE: Only the presence of HEMA does not indicate better clinical performance of adhesive systems.

One-year evaluation of a simplified ethanol-wet bonding technique: a randomized clinical trial.

The objective of this randomized clinical trial was to evaluate the clinical performance of adhesive restorations using a three-step etch-and-rinse adhesive (TSER), a one-step self-etching adhesive (OSSE), and a simplified ethanol-wet bonding technique (EWBT) prior to the application of a composite resin in non-carious cervical lesions. Ninety-three restorations (31 for each group) were placed in 17 patients by a single operator. No cavity preparation was performed. After 6 and 12 months, the restorations were assessed by two previously trained examiners using modified Ryge criteria for retention (kappa=1.00) and marginal adaptation/staining (kappa=0.81), and the results were analyzed by Fisher's exact and Kruskal-Wallis tests, respectively. No significant differences were observed among groups at the 6- and 12-month time points for any of the assessed criteria (p≥0.05). The intra-group analysis performed by Cochran's test (for retention) and Wilcoxon test (for marginal adaptation/staining) revealed significant differences between the baseline/12-month time intervals in marginal adaptation in OSSE (p=0.0180) and in marginal staining in TSER (p=0.0117). The survival analysis for retention criteria performed using a log-rank test did not show significant differences (p>0.05). The restorations placed using the simplified EWBT performed equally well as the other adhesive strategies employed.

A clinical report of Type III dens invaginatus: relevant aspects of a combined therapeutic approach.

Dens invaginatus is a developmental abnormality that alters dental morphology; as a result, treating this condition is a challenge for endodontic practices. This article describes how a combination of nonsurgical and surgical therapies was utilized to treat a maxillary central incisor with Type III dens invaginatus and vital pulp. The treatment plan included using computed tomography (CT) for a detailed analysis of the dental anatomy and periapical area, endodontic and surgical procedures, and a 4-year follow-up period that included periodic clinical and radiographic examinations. The follow-up examinations revealed a regression of the apical lesion and no other signs or symptoms. Based on the present case report, the authors concluded that this combination of surgical and nonsurgical approaches was effective and that CT is a valuable auxiliary tool for the study of dental anatomy.

Low shrinkage composite resins: influence on sealing ability in unfavorable C-factor cavities.

The present investigation observed the sealing ability of low shrinkage composite resins in large and deep cavities, placed and photocured in one increment. Large, deep cavities (5.0 mm diameter and 2.5 mm deep) surrounded by enamel were prepared in bovine teeth, which were then divided into five groups. Groups 1, 2, 3 and 4: acid conditioning + Adper Single Bond (3M/ESPE, St Paul, MN, USA) and restoration with Aelite LS Posterior (BISCO Inc. Schaumburg, IL, USA) (G1); Filtek Z-350 (3M/ESPE,St Paul, MN, USA) (G2); Filtek Z-350 Flow (3M/ESPE, St Paul, MN, USA) (G3); Premisa (KERR Corporation, Orange, CA, USA) (G4). Group 5: Silorane Adhesive system (3M/ESPE, St Paul, MN, USA) + restoration with Filtek Low Shrinkage Posterior P90 (3M/ESPE, St Paul, MN, USA). After polymerization, the teeth were immersed in 0.5% basic fuchsine solution and immediately washed. Using the Imagetool Software, the extent of dye along the margins was calculated as a percentage of total perimeter. The restorations were then transversally sectioned and the depth of dye penetration was calculated in mm, using the same software. Kruskal-Wallis analysis for all groups showed no statistical differences for extent (p = 0.54) or depth (p = 0.8364) of dye penetration. According to this methodology, the so-called low shrinkage composite resins had the same sealing ability compared to regular and flowable nanocomposite materials.

Adhesive systems: important aspects related to their composition and clinical use.

This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classified according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-and-rinse systems require a specific acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and deficiencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplified ones due to some chemical associations and interactions. The SEM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

Liner and light exposure: effect on in-vitro Class V microleakage.

This in vitro study evaluated the influence of different glass ionomer liners and curing methods on microleakage of resin composite restorations. Class V root preparations were made in 120 bovine incisors randomly divided into 12 groups according to liner and curing method. The resin composite system (Single Bond + Z100) was inserted and polymerized in one increment in all groups. Cavity preparations were either not lined (control), lined with a resin modified glass-ionomer cement (Vitrebond) or a conventional glass-ionomer cement (Ketac Bond). The restorations were light-cured using one of four curing methods. The teeth were thermocycled and immersed in 0.5% basic fuchsin, sectioned, and dye penetration was measured (Image Tool). No significant difference in leakage among conventional, ramp or pulse-delay methods was seen. High intensity light groups showed significantly greater penetration compared to other curing methods. No significant difference existed in marginal leakage between liners, but microleakage was significantly higher in groups restored using no liner. No relationship between lining technique and light curing method was observed. The use of glass ionomer liners reduced microleakage, while high intensity light curing produced the greatest dye penetration.

Effect of the cavity configuration factor on the marginal microleakage of esthetic restorative materials.

PURPOSE: To evaluate the effect of the cavity configuration factor (CF) on the marginal microleakage of cervical restorations with four aesthetic restorative materials. MATERIALS AND METHODS: Conventional cavities, 2.9 mm in diameter and 1.5 mm deep, with CF=2.7 and "saucer"-shaped ones with CF=2 were created in 60 extracted premolars. The following groups were established: G1: Z100/Single Bond, G2: Freedom/Stae, G3: Vitremer/Primer and G4: Durafill/Durafill Bond, following each manufacturer's directions. Thermocycling of the specimens was performed in an aqueous solution of 2% buffered methylene blue, with the temperature varying between 5 to 55 degrees C, for a total of cycles of 60 minutes per day, for 7 days. The specimens were then sectioned and evaluated by two observers using photographs acquired from a stereomicroscope. The values were subjected to Kruskal-Wallis analysis and the Dunn and Wilcoxon test. RESULTS: The averages of the microleakage scores observed in the conventional and "saucer"-shaped cavities were respectively: G1: 0.66/0.46; G2: 0.92/0.69; G3: 1.8/1.86; G4: 3.54/2.3.