Is composite repair suitable for anterior restorations? A long-term practice-based clinical study.

OBJECTIVES: This study investigated the impact in survival, when repair is seen as failure or not, in anterior composite restorations with a retrospective 15-year follow-up study. MATERIALS AND METHODS: Data was collected from patients' files of a private dental practice, including patients with direct composite restorations placed in anterior teeth (class III, class IV, or veneer) between January 1994 and December 2009. Data were analyzed considering or not repair as failure. Statistical analysis was performed with log rank test, Kaplan-Meier, and Cox regression (p < .05). RESULTS: One hundred forty-four patients' files were included, with 634 restorations. At 15 years, Class III / IV restorations showed 69% survival and 2.4% annual failure rate (AFR) when repair was not considered as failure, and 64% and 2.9% AFR, respectively, when repair was seen as failure. For direct veneers, at 5 and 10 years of follow-up, survival dropped from 85% to 74% and from 52% to 38% respectively, when repair was considered as failure. In general, restorations placed in the upper jaw showed increased risk for failure compared to the lower jaw (p < .01), and restorations in central incisors presented a higher risk for failure compared to canines (p < .01). CONCLUSION: Composite repair seems a suitable alternative for class III, class IV, and veneer restorations since it was able to increase the survival of restorations performed in anterior teeth. CLINICAL RELEVANCE: Composite repair for anterior restorations is a suitable restorative treatment option and presents benefits over replacement, including the preservation of sound tooth structures, reduced clinical chair time, and patient anxiety.

Bonding Efficacy and Fracture Pattern of Adhesives Submitted to Mechanical Aging with the Rub&Roll Device.

PURPOSE: To evaluate the effect of water storage and cyclic loading on the microtensile bond strength (µTBS) and fracture pattern of adhesives to dentin. MATERIALS AND METHODS: Midcoronal dentin surfaces (n = 36) were prepared and composite restorations were built up using two adhesives (self-etch and etch-and-rinse). The specimens were randomly divided into 3 groups according to the aging conditions (n = 6): 1. CONTROL: storage in water for 24 h (CO); 2. water storage: storage in water for 6 months (WS); 3. mechanical loading: 750,000 mechanical cycles (ML) using the Rub&Roll loading device. Specimens were sections into beams and the µTBS was tested. Fracture patterns were analyzed using stereomicroscopy and fractographic analysis was performed using SEM. µTBS data (n = 53-72 specimens) were subjected to two-way ANOVA and Tukey's post-hoc test. The chi-squared test was used to compare the distribution of failure modes (p < 0.05). RESULTS: Aging conditions and adhesives significantly affected µTBS (p < 0.01). The CO group showed no difference between materials and had highest µTBS. After WS, the self-etch adhesive showed higher µTBS than did the etchand- rinse adhesive. ML resulted in lower µTBS for both adhesives. Materials (p < 0.01) and aging (p < 0.01) significantly influenced the distribution of failure modes. SEM analysis showed that specimens submitted to WS or ML showed features of degradation and fatigue at the fractured interface, depending on the adhesive. CONCLUSION: Mechanical loading had a negative effect on the bonding efficacy of both adhesives and influenced the fracture pattern, with specimens presenting a different fracture surface from that observed in water-stored specimens.

Secondary Caries Development in in situ Gaps next to Composite and Amalgam.

This in situ study investigated the secondary caries development in dentin in gaps next to composite and amalgam. For 21 days, 14 volunteers wore a modified occlusal splint containing human dentin samples with an average gap of 215 µm (SD=55 µm) restored with three different materials: Filtek Supreme composite, Clearfil AP-X composite and Tytin amalgam. Eight times a day, the splint with samples was dipped in a 20% sucrose solution for 10 min. Before and after caries development, specimens were imaged with transversal wavelength independent microradiography, and lesion depth (LD) and mineral loss (ML) were calculated. The LD and ML of the three restoration materials were compared within patients using paired t tests (α=5%). In total 38 composite samples (Filtek n=19 and AP-X n=19) and 19 amalgam samples could be used for data analysis. AP-X composite presented the highest mean values of LD and ML of the three restorative materials. Amalgam showed statistically significantly less ML (Δ=452 µm×vol%) than the combined composite materials (p=0.036). When comparing amalgam to the separate composite materials, only AP-X composite showed higher ML (Δ=515 µm×vol%) than amalgam (p=0.034). Analysis of LD showed the same trends, but these were not statistically significant. In conclusion, amalgam showed reduced secondary caries progression in dentin in gaps compared to composite materials tested in this in situ model.

Does air particle abrasion affect the flexural strength and phase transformation of Y-TZP? A systematic review and meta-analysis.

OBJECTIVES: A systematic review was conducted to assess the effects of air-particle abrasion procedures on the mechanical strength and phase transformation of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). DATA: This report followed the PRISMA Statement. From 1013 eligible studies, 78 were selected for full-text analysis, from which 37 were excluded. The 41 remaining papers were included for the systematic review; hand-searching yielded three papers. The review comprised a total of 44 studies; 21 were included in the meta-analysis. SOURCES: Searches were performed with no publication year limit through November 2015 in PubMed/MEDLINE, Web of Science (Core Collection) and Scopus databases. STUDY SELECTION: In vitro studies evaluating the effect of air-particle abrasion protocols on the mechanical strength and/or phase transformation of Y-TZP zirconia specimens, immediately or after aging. For the meta-analysis, flexural strength data of air-particle abrasion vs. control (nonabraded) were globally and subgroup analyzed. Subgroup analyses assessed blasting parameters (particle size, pressure, or time duration) and the effect of aging. Statistical analyses were conducted using RevMan 5.1 (Cochrane Collaboration, Copenhagen, Denmark). Comparisons were performed with random-effect models at a 5% significance level. Phase transformation data were included only in the systematic review, as insufficient data were available for meta-analysis. CONCLUSIONS: Airborne-particle abrasion improved flexural strength of Y-TZP, regardless of abrasion parameters and the presence or lack of aging (p≤0.05). Phase transformation tended to be increased by air abrasion immediately or with up to 2h of aging. However, after aging for 12h or more, the abraded Y-TZP showed less monoclinic content than the control.

Failed bonded interfaces submitted to microcosm biofilm caries development.

OBJECTIVES: This study aimed to evaluate the dentin wall carious lesion development of different composite-dentin interfaces in the presence of two adhesive bonding materials in the gaps, using a microcosm biofilm model. METHODS: Dentin samples were prepared (10.4mm(2)) and restored with a composite resin using two adhesive systems (etch-and-rinse and self-etch techniques). Different conditions with respect to composite-dentin interfaces were produced with a 200µm gap: failed bonded without ageing or after mechanical ageing, or non-bonded with or without the presence of adhesive material on the dentin wall. For cariogenic challenge, specimens were subjected to a biofilm microcosm model for 14days to create caries-like wall lesions. Before and after caries development, transverse wavelength-independent microradiography images were taken, and lesion depth and mineral loss were measured. Data were analysed with linear regression models (p<0.05). RESULTS: The composite-dentin interface conditions significant influenced the caries development: lesion development was reduced by the presence of the adhesive material on dentin wall, while lesion development was increased by the mechanical ageing (p=0.019). There was no difference between the adhesive materials (p values>0.05). CONCLUSION: Different composite-dentin interfaces influence wall lesion development in gaps, with the interfaces submitted to ageing showing less carious protection than those interfaces with the presence of adhesive covering the dentin. CLINICAL SIGNIFICANCE: The presence of adhesive bonding material in the gaps plays a role on the wall caries lesion development.

Behavior of failed bonded interfaces under in vitro cariogenic challenge.

OBJECTIVE: This in vitro study aimed to compare dentin wall caries development at different composite-dentin interfaces. METHODS: Dentin samples (10.4 mm(2)) were restored with composite resin using two adhesive systems (etch-and-rinse and self-etch techniques). Different composite-dentin interfaces with gaps were produced: (a) failed bonded, which were fractured at interface after being submitted to aging protocols (no aging, mechanical loading or water storage); (b) non-bonded interfaces, both without any adhesive material or with adhesive material applied only on the dentin. Adhesively fractured and non-bonded samples were subjected to a lactic acid gel (pH=5) caries model with a continuous opening/closing movement of the interfacial gap for 10 days. Transverse wavelength-independent microradiographs were taken, and lesion depth and mineral loss were measured. Data were analyzed with linear mixed-effects regression models. RESULTS: Caries development differed among the composite-dentin interfaces (p<0.001). The non-bonded interface with adhesive material on the dentin showed less lesion depth than the failed bonded groups, while the non-bonded interface without adhesive on dentin showed the deepest wall lesions. Difference between the adhesive systems was observed only in the non-bonded groups (p=0.003), with the self-etch adhesive applied on the dentin showing more severe lesions. Samples broken after mechanical loading aging showed deeper lesions than those broken after water storage (p<0.001). SIGNIFICANCE: Composite-dentin interfaces failed after aging presented different demineralization from interfaces that were never bonded, indicating that the restorative treatment changes the tissue in a way relevant to secondary caries development.

Microshear bonding effectiveness of different dentin regions.

AIM: The aim of this in vitro study was to evaluate the influence of dentin surfaces with different tubule orientation on bond strength of a multimode adhesive system. MATERIALS AND METHODS: Twenty human molars were selected and prepared in different ways in order to produce different dentin regions. The teeth were randomized (n = 5) according to the application modes of a multimode adhesive system (etch-and-rinse and self-etching) and to the dentin region (occlusal and proximal - 1.5 mm depth from dentinoenamel junction). Cylindrical restorations were performed on dentin with a starch tube. The samples remained immersed in distilled water for 24 h and the microshear bond strength (µSBS) test was performed. The µSBS values were expressed in MPa and analyzed with ANOVA and Tukey's test (P < 0.05). RESULTS: There was no significant difference in the bond strength values between the application modes of the adhesive system (P = 0.19); however, the dentin regions (P < 0.05) significantly affected the µSBS. The proximal dentin presented higher bond strength values than occlusal dentin. CONCLUSION: The dentin surfaces with different tubule orientation influenced the bonding effectiveness of the adhesive system tested.

Wall-lesion development in gaps: The role of the adhesive bonding material.

OBJECTIVES: This study evaluated the caries wall lesion development in different composite-dentin interfaces to investigate if the presence and location of two bonding materials in the gaps influence wall caries lesion development. METHODS: Fourteen volunteers wore a modified occlusal splint containing samples with four different interfaces: perfect bonding/no gap, or with a fixed gap (234±30 µm) with either no bonding material, bonding material (Clearfil Protect Bond-PB and Clearfil SE Bond-SE) on dentin or on composite. Eight times a day, the samples were dipped in 20% sucrose solution for 10 min, during 3 weeks. The samples were imaged with microradiography (T-WIM), and lesion depth (LD) and mineral loss (ML) were measured. The data were analysed with paired t-test. RESULTS: The perfect bonding group did not show any caries wall lesion development, whereas all other interfaces did. The interface with bonding on dentin did not show significantly different wall lesion development from the interface with no material. However, when bonding was present on composite, both LD and ML were significantly higher than both other gap conditions (p-values<0.05). A difference between the bonding material was only seen when applied on composite: PB showed less ML than SE (p=0.01). CONCLUSIONS: The presence of bonding on the composite side of a composite-dentin gap increased wall lesion development in situ. CLINICAL SIGNIFICANCE: The presence and location of an adhesive bonding material in the composite-dentin gaps plays a role on the wall caries lesion development.